- Corbino disk

by Kyrylo Snizhko25 Jul 2014 16:42 - Quantum-size electrostatic potential

by Prof. Michael V. Moskalets06 May 2014 17:44 - Dwyer-Fried invariant

by Prof. Alex Suciu15 Dec 2013 03:22 - General relativity

by Wilson Yu13 Dec 2013 04:40 - High angular resolution

by Prof. Hontas Farmer22 Nov 2013 11:14 - Quantum shot noise

by Prof. Carlo Beenakker04 Feb 2014 08:52 - Andreev reflection

by Prof. Carlo Beenakker08 Dec 2010 13:33 - Neutrino Minimal Standard Model

by Prof. Mikhail Shaposhnikov10 Jan 2011 23:58 - Full counting statistics

by Dr. Dmitri Ivanov28 Nov 2011 09:44 - Geometric flattening

by Dr. Ganna Ivashchenko05 Dec 2010 22:14

- Photonic devices involving many optical modes promise major advances in quantum technologies, with applications ranging from quantum metrology over quantum computing to quantum simulations. A significant current roadblock for the development of such devices, however, is the lack of practical reliable certification tools. Here, we present one such tool. We start by carefully defining different notions of quantum-state certification tests. Then, we introduce an experimentally friendly, yet mathematically rigorous, certification test for experimental preparations of arbitrary m-mode pure Gaussian states as well as a class of pure non-Gaussian states common in linear-optical experiments, including those given by a Gaussian unitary acting on Fock basis states with n bosons. The protocol is efficient for all Gaussian states and all mentioned non-Gaussian states with constant n. We follow the formal mindset of an untrusted prover, who prepares the state, and a skeptic certifier, equipped only with classical computing and single-mode measurement capabilities. No assumptions are made on the type of quantum noise or experimental capabilities of the prover. We build upon an extremality property that leads to a practical fidelity lower bound, interesting in its own right. Experimentally, our technique relies on single-mode homodyne detection. With this method, the efficient and reliable certification of large-scale photonic networks, with a constant number of input photons, as those used for photonic quantum simulations, boson samplers, and quantum metrology is within reach.SimulationsNon-GaussianityExpectation ValueQuantum technologyBosonizationQuadratureQuantum metrologyHomodyne detectionQuantum computerEntanglement...
- Noise is often regarded as anathema to quantum computation, but in some settings it can be an unlikely ally. We consider the problem of learning the class of $n$-bit parity functions by making queries to a quantum example oracle. In the absence of noise, quantum and classical parity learning are easy and almost equally powerful, both information-theoretically and computationally. We show that in the presence of noise this story changes dramatically. Indeed, the classical learning problem is believed to be intractable, while the quantum version remains efficient. Depolarizing the qubits at the oracle's output at any constant nonzero rate does not increase the computational (or query) complexity of quantum learning more than logarithmically. However, the problem of learning from corresponding classical examples is the Learning Parity with Noise (LPN) problem, for which the best known algorithms have superpolynomial complexity. This creates the possibility of observing a quantum advantage with a few hundred noisy qubits. The presence of noise is essential for creating this quantum-classical separation.QubitQuantum computerQuantum algorithmQuantum coherenceParity learningDephasingNP-hard problemHadamard transformQuantum error correctionUniform distribution...
- We compare the results from several sets of cosmological simulations of cosmic reionization, produced under Cosmic Reionization On Computers (CROC) project, with existing observational data on the high-redshift Ly-alpha forest and the abundance of Ly-alpha emitters. We find good consistency with the observational measurements and the previous simulation work. By virtue of having several independent realizations for each set of numerical parameters, we are able to explore the effect of cosmic variance on observable quantities. One unexpected conclusion we are forced into is that cosmic variance is unusually large at z>6, with both our simulations and, most likely, observational measurements are still not fully converged for even such basic quantities as the average Gunn-Peterson optical depth or the volume-weighted neutral fraction.SimulationsReionizationGalaxyIonizationStar formationCosmic varianceAbsorptivityLuminosity functionIntergalactic mediumHistory of the reionization...
- I review current efforts to measure the mean density of dark matter near the Sun. This encodes valuable dynamical information about our Galaxy and is also of great importance for 'direct detection' dark matter experiments. I discuss theoretical expectations in our current cosmology; the theory behind mass modelling of the Galaxy; and I show how combining local and global measures probes the shape of the Milky Way dark matter halo and the possible presence of a 'dark disc'. I stress the strengths and weaknesses of different methodologies and highlight the continuing need for detailed tests on mock data - particularly in the light of recently discovered evidence for disequilibria in the Milky Way disc. I highlight several recent measurements in order of increasing data complexity and prior, and, correspondingly, decreasing formal error bars. Comparing these measurements with spherical extrapolations from the Milky Way's rotation curve, I show that the Milky Way is consistent with having a spherical dark matter halo at the Solar position R0. The very latest measures based on ~10,000 stars from the Sloan Digital Sky Survey appear to favour little halo flattening at R0, suggesting that the Galaxy has a rather weak dark matter disc, with a correspondingly quiescent merger history [Abridged].StarMilky WayDark matterSimulationsDark matter haloRotation CurveEllipticitySloan Digital Sky SurveyGalaxySun...
- The nature of the dark sector of the Universe remains one of the outstanding problems in modern cosmology, with the search for new observational probes guiding the development of the next generation of observational facilities. Clues come from tension between the predictions from {\Lambda}CDM and observations of gravitationally lensed galaxies. Previous studies showed that galaxy clusters in the {\Lambda}CDM are not strong enough to reproduce the observed number of lensed arcs. This work aims to constrain the warm dark matter cosmologies by means of the lensing efficiency of galaxy clusters drawn from these alternative models. The lensing characteristics of two samples of simulated clusters in the warm dark matter ({\Lambda}WDM) and cold dark matter ({\Lambda}CDM) cosmologies have been studied. The results show that even though the CDM clusters are more centrally concentrated and contain more substructures, the WDM clusters have slightly higher lensing efficiency than their CDM counterparts. The key difference is that WDM clusters have more extended and more massive subhaloes than CDM analogues. These massive substructures significantly stretch the critical lines and caustics and hence they boost the lensing efficiency of the host halo. Despite the increase in the lensing efficiency due to the contribution of massive substructures in the WDM clusters, this is not enough to resolve the arc statistics problem.Cluster of galaxiesWarm dark matterCold dark matterEinstein radiusCosmologyDark matter subhaloSimulationsA giantsCritical lineLine of sight...
- Relic neutrinos play an important role in the evolution of the Universe, modifying some of the cosmological observables. We summarize the main aspects of cosmological neutrinos and describe how the precision of present cosmological data can be used to learn about neutrino properties. In particular, we discuss how cosmology provides information on the absolute scale of neutrino masses, complementary to beta decay and neutrinoless double-beta decay experiments. We explain why the combination of Planck temperature data with measurements of the baryon acoustic oscillation angular scale provides a strong bound on the sum of neutrino masses, 0.23 eV at the 95% confidence level, while the lensing potential spectrum and the cluster mass function measured by Planck are compatible with larger values. We also review the constraints from current data on other neutrino properties. Finally, we describe the very good perspectives from future cosmological measurements, which are expected to be sensitive to neutrino masses close the minimum values guaranteed by flavour oscillations.NeutrinoNeutrino massCosmic microwave backgroundPlanck missionCosmologyBaryon acoustic oscillationsSterile neutrinoFree streamingHubble Space TelescopeCluster of galaxies...
- This is the LaTeX version of my book "Particle Physics and Inflationary Cosmology'' (Harwood, Chur, Switzerland, 1990). I decided to put it to hep-th, to make it easily available. Many things happened during the 15 years since the time when it was written. In particular, we have learned a lot about the high temperature behavior in the electroweak theory and about baryogenesis. A discovery of the acceleration of the universe has changed the way we are thinking about the problem of the vacuum energy: Instead of trying to explain why it is zero, we are trying to understand why it is anomalously small. Recent cosmological observations have shown that the universe is flat, or almost exactly flat, and confirmed many other predictions of inflationary theory. Many new versions of this theory have been developed, including hybrid inflation and inflationary models based on string theory. There was a substantial progress in the theory of reheating of the universe after inflation, and in the theory of eternal inflation. It's clear, therefore, that some parts of the book should be updated, which I might do sometimes in the future. I hope, however, that this book may be of some interest even in its original form. I am using it in my lectures on inflationary cosmology at Stanford, supplementing it with the discussion of the subjects mentioned above. I would suggest to read this book in parallel with the book by Liddle and Lyth "Cosmological Inflation and Large Scale Structure,'' with the book by Mukhanov "Physical Foundations of Cosmology,'' to be published soon, and with my review article hep-th/0503195, which contains a discussion of some (but certainly not all) of the recent developments in inflationary theory.Inflationary universeCosmologyScalar fieldPhase transitionsHomogenizationEffective potentialSpace-time singularityVacuum energyCondensationDe Sitter space...
- According to the photo-heating model of the intergalactic medium (IGM), He II reionization is expected to affect its thermal evolution. Evidence for additional energy injection into the IGM has been found at $3\lesssim z\lesssim4$, though the evidence for the subsequent fall-off below $z\sim2.8$ is weaker and depends on the slope of the temperature--density relation, $\gamma$. Here we present, for the first time, an extension of the IGM temperature measurements down to the atmospheric cut-off of the H I Lyman-$\alpha$ forest at $z\simeq1.5$. Applying the curvature method on a sample of 60 UVES spectra we investigated the thermal history of the IGM at $z<3$ with precision comparable to the higher redshift results. We find that the temperature of the cosmic gas traced by the Ly-$\alpha$ forest [$T(\bar{\Delta})]$ increases for increasing overdensity from $T(\bar{\Delta})\sim 22670$ K to 33740 K in the redshift range $z\sim2.8-1.6$. Under the assumption of two reasonable values for $\gamma$, the temperature at the mean density ($T_{0}$) shows a tendency to flatten at $z\lesssim 2.8$. In the case of $\gamma\sim1.5$, our results are consistent with previous ones which indicate a falling $T_{0}$ for redshifts $z\lesssim2.8$. Finally, our $T(\bar{\Delta})$ values show reasonable agreement with moderate blazar heating models.CurvatureIntergalactic mediumSimulationsReionizationQuasarMean mass densityEffective optical depthBlazarTemperature-density relationTemperature measurement...
- We develop a general method to compute correlation functions of fractional quantum Hall (FQH) states on a curved space. In a curved space, local transformation properties of FQH states are examined through local geometric variations, which are essentially governed by the gravitational anomaly. Furthermore, we show that the electromagnetic response of FQH states is related to the gravitational response (a response to curvature). Thus, the gravitational anomaly is also seen in the structure factor and the Hall conductance in flat space. The method is based on iteration of a Ward identity obtained for FQH states.Fractional quantum Hall stateTwo-point correlation functionGravitational anomalyCurvatureHall conductanceFilling fractionHolomorphHall viscosityLowest Landau LevelLaplace-Beltrami operator...
- We study the CP violation in lepton number violating meson decays $M^{\pm} \to \ell_1^{\pm} \ell_2^{\pm} M^{' \mp}$, where $M$ and $M^{'}$ are pseudoscalar mesons, $M=K, D, D_s, B, B_c$ and $M^{'}=\pi, K, D, D_s$, and the charged leptons are $\ell_1, \ell_2 = e, \mu$. It turns out that the CP-violating difference $S_{-}(M) \equiv [\Gamma(M^- \to \ell_1^- \ell_2^- M^{' +})-\Gamma(M^+ \to \ell_1^+ \ell_2^+ M^{' -})]$ can become appreciable when two intermediate on-shell Majorana neutrinos $N_j$ ($j=1,2$) participate in these decays. Our calculations show that the asymmetry becomes largest when the masses of $N_1$ and $N_2$ are almost degenerate, i.e., when the mass difference $\Delta M_N$ becomes comparable with the (small) decay widths $\Gamma_N$ of these neutrinos: $\Delta M_N \not\gg \Gamma_N$. We show that in such a case, the CP ratio ${\cal A}_{CP}(M) \equiv [\Gamma(M^- \to \ell_1^- \ell_2^- M^{' +})-\Gamma(M^+ \to \ell_1^+ \ell_2^+ M^{' -})]/[\Gamma(M^- \to \ell_1^- \ell_2^- M^{' +})+\Gamma(M^+ \to \ell_1^+ \ell_2^+ M^{' -})]$ becomes a quantity $\sim 1$. The observation of CP violation in these decays would be consistent with the existence of the well-motivated $\nu$MSM model with two almost degenerate heavy neutrinos in the mass range between $M_N \sim 0.1$-$10^1$ GeV.NeutrinoCP violationDecay widthMajorana neutrinoSterile neutrinoLepton flavour violationStandard ModelSemihadronic decaysCharged leptonPseudoscalar meson...
- Recent high-resolution simulations that include Cold Dark Matter (CDM) and baryons have shown that baryonic physics can dramatically alter the dark matter structure of galaxies. These results modify our predictions for observed galaxy evolution and structure. Given these updated expectations, it is timely to re-examine observational constraints on the dark matter model. A few observations are reviewed that may indirectly trace dark matter, and may help confirm or deny possible dark matter models. Warm Dark Matter (WDM) and Self-Interacting Dark Matter (SIDM) are currently the favorite alternative models to CDM. Constraints on the WDM particle mass require it to be so heavy that WDM is nearly indistinguishable from CDM. The best observational test of SIDM is likely to be in the dark matter distribution of faint dwarf galaxies, but there is a lack of theoretical predictions for galaxy structure in SIDM that account for the role of baryons.Cold dark matterDark matterGalaxyWarm dark matterSelf-interacting dark matterSimulationsWDM particlesStar formationDwarf galaxyThermalisation...
- Dwarf spheroidal (dSph) galaxies are among the most promising targets for the indirect detection of dark matter (DM) from annihilation and/or decay products. Empirical estimates of their DM content - and hence the magnitudes of expected signals - rely on inferences from stellar-kinematic data. However, various kinematic analyses can give different results and it is not obvious which are most reliable. Using extensive sets of mock data of various sizes (mimicking 'ultra-faint' and 'classical' dSphs) and an MCMC engine, here we investigate biases, uncertainties, and limitations of analyses based on parametric solutions to the spherical Jeans equation. For a variety of functional forms for the tracer and DM density profiles, as well as the orbital anisotropy profile, we examine reliability of estimates for the astrophysical J- and D-factors for annihilation and decay, respectively. For large (N > 1000) stellar-kinematic samples typical of 'classical' dSphs, errors tend to be dominated by systematics, which can be reduced through the use of sufficiently general and flexible functional forms. For small (N < 100) samples typical of 'ultrafaints', statistical uncertainties tend to dominate systematic errors and flexible models are less necessary. Finally, we find that the assumption of spherical symmetry can bias estimates of J (by up to a factor of a few) when the object is mildly triaxial (axis ratios b/a=0.8, c/a=0.6). A concluding table summarises the typical error budget and biases for the different sample sizes considered. We also define an optimal strategy that would mitigate sensitivity to priors and other aspects of analyses based on the spherical Jeans equation.Dark Matter Density ProfileDwarf spheroidal galaxyDark matterJeans equationMonte Carlo Markov chainVelocity dispersionOrientationVelocity dispersion profileDark matter haloKinematics...
- We study the two-body baryonic $B$ and $D_s$ decays based on the annihilation mechanism without the partial conservation of axial-vector current (PCAC) at the GeV scale. We demonstrate that the contributions of $B^-\to \Lambda\bar p$, $B^-\to \Sigma^0 \bar p$ and $\bar B^0_s\to \Lambda\bar \Lambda$ are mainly from the (pseudo)scalar currents with their branching ratios predicted to be around $(3.4,\,7.1,\,5.6)\times 10^{-8}$, respectively, exactly the sizes of ${\cal B}(B\to {\bf B\bar B'})$ established by the data. We are able to apply the annihilation mechanism to all of the charmless two-body baryonic $B$ and $D_s$ decays. In particular, we can explain ${\cal B}(\bar B^0_{(s)}\to p\bar p)$ of order $10^{-8}$ and ${\cal B}(D_s^+\to p\bar n)$ of order $10^{-3}$, which are from the axial-vector currents. In addition, the branching ratios of $\bar B^0\to \Lambda\bar \Lambda$, $B^-\to n\bar p$, and $B^-\to \Sigma^- \bar\Sigma^0$ are predicted to be $(0.5,\,2.2,\,11.1)\times 10^{-8}$, which can be measured by LHCb and viewed as tests for the violation of PCAC at the GeV scale.AmplitudeBranching ratioForm factorDecay modeLHCbPair productionDibaryonFlavour symmetryMomentum transferQuark...
- The prospects are explored for testing Lorentz and CPT symmetry in the muon sector via the spectroscopy of muonium and various muonic atoms, and via measurements of the anomalous magnetic moments of the muon and antimuon. The effects of Lorentz-violating operators of both renormalizable and nonrenormalizable dimensions are included. We derive observable signals, extract first constraints from existing data on a variety of coefficients for Lorentz and CPT violation, and estimate sensitivities attainable in forthcoming experiments. The potential of Lorentz violation to resolve the proton radius puzzle and the muon anomaly discrepancy is discussed.Lorentz violationMuonChiral perturbation theoryEarthBound stateExpectation ValueJ-PARCFermilabSunProton radius...
- We consider the problem of reconstructing global quantum states from local data. Because the reconstruction problem has many solutions in general, we consider the reconstructed state of maximal global entropy consistent with the local data. We show that unique ground states of local Hamiltonians are exactly reconstructed by taking the maximal entropy state. More generally, we show that if the state in question is a ground state of a local Hamiltonian with a degenerate subspace of locally indistinguishable ground states, then the maximal entropy state is close to the ground state projector. We show that perfect local reconstruction is also possible for thermal states of local Hamiltonians. Finally, we discuss a procedure to certify that the reconstructed state is close to the true global state. We call the entropy of our reconstructed maximum entropy state the "reconstruction entropy", and we discuss its relation to emergent geometry in the context of holographic duality.EntropyHamiltonianDualityBlack holeEntanglement entropyQuantum field theoryGround state manifoldExpectation ValueTopological orderFree fermions...
- Very high energy gamma ray emission from the active galactic nucleus PG 1553+113 was observed during 2005 and 2006 by the MAGIC collaboration, for a total observation time of 18.8 hours. Here we present the results of follow up observations: more than 20 hours of good quality data collected by the MAGIC Telescope during the 2007 and 2008 campaigns. The obtained spectra are compared and combined with previous measurements, and corrected for absorption adopting different EBL models. Upper limits on the unknown source redshift are derived by assuming the absence of a break in the intrinsic spectrum, or alternatively by constraining the hardness of the intrinsic source spectrum.MAGIC telescopeExtragalactic background lightActive Galactic NucleiAbsorptivityTelescopesPoint spread functionHadronizationZenithStatisticsHost galaxy...
- We present new far-ultraviolet spectra from the Cosmic Origins Spectrograph (HST/COS) of the BL Lac object 1ES1553+113 covering the wavelength range 1135-1795 A. The data show a smooth continuum with a wealth of narrow absorption features arising in the ISM and IGM. These features include 41 Lya absorbers at 0<z<0.43, fourteen of which are detected in multiple Lyman lines and six in one or more metal lines. We analyze a metal-rich triplet of Lya absorbers at z=0.188 in which OVI, NV, and CIII absorption is detected. Silicon ions (SiIII/IV) are not detected to fairly strong upper limits, and we use the measured SiIII/CIII upper limit to derive an abundance limit [C/Si]>0.6 for the strongest component of the absorber complex. Galaxy redshift surveys show a number of massive galaxies at approximately the same redshift as this absorption complex, suggesting that it arises in a large-scale galaxy filament. As one of the brightest extragalactic X-ray and gamma-ray sources, 1ES1553+113 is of great interest to the high-energy astrophysics community. With no intrinsic emission or absorption features, 1ES1553+113 has no direct redshift determination. We use intervening Lya absorbers to place a direct limit on the redshift: z_em>0.395 based on a confirmed Lya+OVI absorber and z_em>0.433 based on a single-line detection of Lya. COS/FUV data are only sensitive to Lya absorbers at z<0.47, but we present statistical arguments that z_em<0.58 based on the non-detection of any Lyb absorbers at z>0.4.AbsorbanceAbsorptivityIntergalactic mediumCosmic Origins SpectrographAbsorption featureBL LacertaeAbundanceSpectral energy distributionInterstellar mediumGalaxy...
- Superluminal neutrinos are expected to lose energy due to bremstrauhlung. It is dominated by e+e--pair production if kinematically allowed. The same signature was used in searches for 3-body decays of hypothetical heavy sterile neutrinos. From the absence of these processes in CERN PS191 and CHARM experiments we set upper limits on the neutrino velocity in the energy range from 0.2 GeV to 280 GeV. Our limits are well below the neutrino velocity favored by the recent OPERA results. For energy-independent neutrino velocity the limits obtained in this paper are stronger than those coming from ICARUS experiment and observations of Supernova SN1987a.NeutrinoSterile neutrinoCERNOPERA experimentMuon neutrinoStandard ModelPair productionNeutrino beamSupernova 1987AStatistics...
- We consider a singlet fermion dark matter with PQ symmetry. A singlet complex scalar is introduced to mediate between dark matter and the SM through Higgs portal interaction and electroweak PQ anomalies. We show that dark matter annihilation with axion mediation can explain a monochromatic photon line of the Fermi LAT data at 130 GeV by anomaly interactions while the annihilation cross section with Higgs portal interaction is p-wave suppressed. We discuss the interplay between direct detection of the fermion dark matter and the collider search of Higgs-like scalars. We also present a ultra-violet completion of the dark matter model into the NMSSM with PQ symmetry.Dark matterAxionDark matter annihilationStandard ModelGamma-ray linesBranching ratioFERMI telescopePeccei-Quinn symmetryInvisible axionSupersymmetry breaking...
#### Neutrinos and the starsver. 2

The role of neutrinos in stars is introduced for students with little prior astrophysical exposure. We begin with neutrinos as an energy-loss channel in ordinary stars and conversely, how stars provide information on neutrinos and possible other low-mass particles. Next we turn to the Sun as a measurable source of neutrinos and other particles. Finally we discuss supernova (SN) neutrinos, the SN 1987A measurements, and the quest for a high-statistics neutrino measurement from the next nearby SN. We also touch on the subject of neutrino oscillations in the high-density SN context.NeutrinoStarAxionSunSupernovaSolar neutrinoSupernova 1987ACore collapseWhite dwarfShock wave...- Locating the centers of dark matter halos is critical for understanding the mass profiles of halos as well as the formation and evolution of the massive galaxies that they host. The task is observationally challenging because we cannot observe halos directly, and tracers such as bright galaxies or X-ray emission from hot plasma are imperfect. In this paper we quantify the consequences of miscentering on the weak lensing signal from a sample of 129 X-ray selected galaxy groups in the COSMOS field with redshifts 0<z<1 and halo masses in the range 10^13 - 10^14 M_sun. By measuring the stacked lensing signal around eight different candidate centers (such as the brightest member galaxy, the mean position of all member galaxies, or the X-ray centroid), we determine which candidates best trace the center of mass in halos. In this sample of groups, we find that massive galaxies near the X-ray centroids trace the center of mass to <~75 kpc, while the X-ray position and centroids based on the mean position of member galaxies have larger offsets primarily due to the statistical uncertainties in their positions (typically ~50-150 kpc). Approximately 30% of groups in our sample have ambiguous centers with multiple bright or massive galaxies, and these groups show disturbed mass profiles that are not well fit by standard models, suggesting that they are merging systems. We find halo mass estimates from stacked weak lensing can be biased low by 5-30% if inaccurate centers are used and the issue of miscentering is not addressed.GalaxyDark matter subhaloStellar massVirial massMassive galaxiesWeak lensingStatisticsDark matter haloPhotometric redshiftCOSMOS survey...
- The recent measurement of the reactor angle as $\sin^2 2\theta_{13} = 0.092 \pm 0.016(stat) \pm 0.005(syst)$ come from the Daya Bay collaboration. Evidence of nonzero \theta_{13} was also there at T2K, MINOS and Double Chooz experiments. We study the implication of these recent data on neutrino mass matrix and consequently on leptogenesis in a supersymmetric SO(10) model. To explain the smallness of neutrino mass, in general, we require a heavy Majorana neutrino which is a natural candidate in SO(10) model. In minimal SO(10) model, the symmetry breaking scale or the right-handed neutrino mass scale is close to the GUT scale. It is not only beyond the reach of any present or future collider search but the lepton asymmetry generated from its decay is in conflict with the gravitino constraint as well as unable to fit the neutrino data. We show that addition of an extra fermion singlet can accommodate the observed recent neutrino data in a supersymmetric SO(10) model. This model can generate the desired lepton asymmetry and provide TeV scale doubly-charged Higgs scalars to be detected at LHC.NeutrinoNeutrino massLepton asymmetryGravitinoGrand unification theoryGauge coupling constantVacuum expectation valueSterile neutrinoMajorana neutrinoSupersymmetry...
- Background: Good understanding of the cross sections for (anti)neutrino scattering off nuclear targets in the few-GeV energy region is a prerequisite for correct interpretation of results of ongoing and planned oscillation experiments. Purpose: Clarify possible source of disagreement between recent measurements of the cross sections on carbon. Method: Nuclear effects in (anti)neutrino scattering off carbon nucleus are described using the spectral function approach. The effect of two- and multi-nucleon final states is accounted for by applying an effective value of the axial mass, fixed to 1.23 GeV. Neutral-current elastic (NCE) and charged-current quasielastic (CCQE) processes are treated on equal footing. Results: The differential and total cross sections for the energy ranging from a few hundreds of MeV to 100 GeV are obtained and compared to the available data from the BNL E734, MiniBooNE, and NOMAD experiments. Conclusions: Nuclear effects in NCE and CCQE scattering seem to be very similar. Within the spectral function approach, the axial mass from the shape analysis of the MiniBooNE data is in good agreement with the results reported by the BNL E734 and NOMAD Collaborations. However, the combined analysis of NCE and CCQE data does not seem to support the contribution of multi-nucleon final states being large enough to explain the normalization of the MiniBooNE-reported cross sections.NeutrinoForm factorKinematicsAntineutrinoMonte Carlo methodMiniBooNE experimentCharged currentLocal-density approximationWeak neutral current interactionElectron scattering...
- We discuss the neutrino masses and mixings as the realization of an $S_{3}$ flavour permutational symmetry in two models, namely the Standard Model and an extension of the Standard Model with three Higgs doublets. In the $S_3$ Standard Model, mass matrices of the same generic form are obtained for the neutrino and charged leptons when the $S_{3}$ flavour symmetry is broken sequentially. In the minimal $S_{3}$-symmetric extension of the Standard Model, the $S_3$ symmetry is left unbroken, and the concept of flavour is extended to the Higgs sector by introducing in the theory three Higgs fields which are SU(2) doublets. In both models, the mass matrices of the neutrinos and charged leptons are reparametrized in terms of their eigenvalues, and exact, explicit analytical expressions for the neutrino mixing angles as functions of the masses of neutrino and charged leptons are obtained. In the case of the $S_3$ Standard Model, from a $\chi^2$ fit of the theoretical expressions of the lepton mixing matrix to the values extracted from experiment, the numerical values of the neutrino mixing angles are obtained in excellent agreement with experimental data. In the $S_3$ extension of the Standard Model, if two of the right handed neutrinos masses are degenerate, the reactor and atmospheric mixing angles are determined by the masses of the charged leptons, yielding $\theta_{23}$ in excellent agreement with experimental data, and $\theta_{13}$ different from zero but very small. If the masses of the three right handed neutrinos are assumed to be different, then it is possible to get $\theta_{13}$ also in very good agreement with experimental data. We also show the branching ratios of some selected flavour changing neutral currents (FCNC) process as well as the contribution of the exchange of a neutral flavour changing scalar to the anomaly of the magnetic moment of the muon.Neutrino massFlavourNeutrinoStandard ModelQuarkMajorana neutrinoFlavour symmetryExtensions of the standard modelSterile neutrinoFlavour Changing Neutral Currents...
- Using hydrodynamical zoom simulations in the standard LCDM cosmology, we investigate the evolution of the distribution of baryons (gas and stars) in a local group-type universe. First, with standard star formation and supernova feedback prescriptions, we find that the mean baryonic fraction value estimated at the virial radius of the two main central objects (i.e. the Milky Way and Andromeda) is decreasing over time, and is 10-15% lower than the universal value, 0.166, at z=0. This decrease is mainly due to the fact that the amount of accretion of dissipative gas onto the halo, especially at low redshift, is in general much lower than that of the dissipationless dark matter. Indeed, a significant part of the baryons does not collapse onto the haloes and remains in their outskirts, mainly in the form of warm-hot intergalactic medium (WHIM). Moreover, during the formation of each object, some dark matter and baryons are also be expelled through merger events via tidal disruption. In contrast to baryons, expelled dark matter can be more efficiently re-accreted onto the halo, enhancing both the reduction of fb inside Rv, and the increase of the mass of WHIM outside Rv. Varying the efficiency of supernovae feedback at low redshift does not seem to significantly affect these trends. Alternatively, when a significant fraction of the initial gas in the main objects is released at high redshifts by more powerful sources of feedback, such as AGN from intermediate mass black holes in lower mass galaxies, the baryonic fraction at the virial radius can have a lower value (fb~0.12) at low redshift. Hence physical mechanisms able to slow down the accretion of gas at high redshifts will have a stronger impact on the deficit of baryons in the mass budget of Milky Way type-galaxies at present times than those that expel the gas in the longer, late phases of galaxy formation.AccretionVirial radiusDark matterGalaxySupernovaStellar massStarWarm hot intergalactic mediumActive Galactic NucleiHydrodynamical simulations...
- We consider the density profile of the central region of dark matter haloes. It turns out that under very general conditions the profile is universal: it depends almost not at all on the properties of the initial perturbation and is very akin, but not identical, to the Einasto profile. We estimate the size of the 'central core' of the distribution, i.e., the extent of the very central region with a respectively gentle profile, and show that the cusp formation is unlikely, even if the dark matter is cold. We also indicate that the density profile of the outer part ($r>0.5 R_{vir}$) of the haloes significantly depends on the initial conditions and should not be universal, in contrast to the central area. All these results can be useful both to indirect search of the dark matter and to N-body simulations of the structure formation.RelaxationGalaxyDark matterSimulationsNavarro-Frenk-White profileEinasto profileDark matter haloN-body simulationRelaxation timeCore radius...
- We introduce a new photometric estimator of the HI mass fraction (M_HI/M_*) in local galaxies, which is a linear combination of four parameters: stellar mass, stellar surface mass density, NUV-r colour, and g-i colour gradient. It is calibrated using samples of nearby galaxies (0.025<z<0.05) with HI line detections from the GASS and ALFALFA surveys, and it is demonstrated to provide unbiased M_HI/M_* estimates even for HI-rich galaxies. We apply this estimator to a sample of ~24,000 galaxies from the SDSS/DR7 in the same redshift range. We then bin these galaxies by stellar mass and HI mass fraction and compute projected two point cross-correlation functions with respect to a reference galaxy sample. Results are compared with predictions from current semi-analytic models of galaxy formation. The agreement is good for galaxies with stellar masses larger than 10^10 M_sun, but not for lower mass systems. We then extend the analysis by studying the bias of HI-poor or HI-rich galaxies with respect to galaxies with normal HI content on scales between 100 kpc and ~5 Mpc. For the HI-poor population, the strongest bias effects arise when the HI-deficiency is defined in comparison to galaxies of the same stellar mass and size. This is not reproduced by the semi-analytic models, where the quenching of star formation in satellites occurs by "starvation" and does not depend on their internal structure. HI-rich galaxies with masses greater than 10^10 M_sun are found to be anti-biased compared to galaxies with "normal" HI content. Interestingly, no such effect is found for lower mass galaxies.GalaxyStellar massStellar surfacesSloan Digital Sky SurveyDark matter haloAccretionALFALFA surveySatellite galaxyStar formationQuenching...
- Two centuries of research on phase transitions have repeatedly highlighted the importance of critical fluctuations that abound in the vicinity of a critical point. They are at the origin of scaling laws obeyed by thermodynamic observables close to second-order phase transitions resulting in the concept of universality classes, that is of paramount importance for the study of organizational principles of matter. Strikingly, in case such soft fluctuations are too abundant they may alter the nature of the phase transition profoundly; the system might evade the critical state altogether by undergoing a discontinuous first-order transition into the ordered phase. Fluctuation-induced first-order transitions have been discussed broadly and are germane for superconductors, liquid crystals, or phase transitions in the early universe, but clear experimental confirmations remain scarce. Our results from neutron scattering and thermodynamics on the model Dzyaloshinskii-Moriya (DM) helimagnet (HM) MnSi show that such a fluctuation-induced first-order transition is realized between its paramagnetic and HM state with remarkable agreement between experiment and a theory put forward by Brazovskii. While our study clarifies the nature of the HM phase transition in MnSi that has puzzled scientists for several decades, more importantly, our conclusions entirely based on symmetry arguments are also relevant for other DM-HMs with only weak cubic magnetic anisotropies. This is in particular noteworthy in light of a wide range of recent discoveries that show that DM helimagnetism is at the heart of problems such as topological magnetic order, multiferroics, and spintronics.IntensityPhase transitionsDark matterMomentum spaceEffective potentialRenormalizationSkyrmionMagnetizationMagnetic anisotropyCritical point...
- Cosmic Flows is a program to determine galaxy distances for 30,000 galaxies with systematic errors below 2%, almost ten times the number currently known and a five-fold improvement in systematics. The resultant velocity field will provide input for constrained local universe simulations: CLUES (www.clues-project.org). The observed and the simulated universe are then comparatively studied. This synergy of observations and theory distinguishes the program, and should lead to fundamental discoveries regarding the sources of deviations from the expansion of the universe. Specifically, the program should give a definitive answer to one of the most outstanding unsolved problem in cosmology: the cause of the motion of 630 km/s of our Galaxy manifested in the microwave background dipole. This paper presents current results with particular emphasis on the "great attractor" reconstruction.GalaxyPeculiar velocityDark matterPhotometryWide-field Infrared Survey ExplorerSloan Digital Sky SurveyDark energyCosmologyWiener filterCosmic microwave background...
- Upper limits on the spin-independent (SI) as well as spin-dependent (SD) elastic scattering cross sections of WIMPs with protons, imposed by the Super-Kamiokande (S-K) upper limit on the neutrino flux from WIMP annihilation in the Sun, and their compatibility with the "DAMA-compatible" regions of the WIMP parameter space within which the annual modulation signal observed by the DAMA/LIBRA experiment is compatible with the null results of other direct detection experiments, are studied within the frame work of a self-consistent model of the finite-size dark matter (DM) halo of the Galaxy, the parameters of which are determined by a fit to the rotation curve data of the Galaxy. We find that the S-K implied upper limits on the WIMP-proton elastic cross section as a function of WIMP mass impose stringent restrictions on the branching fractions of the various WIMP annihilation channels. For SI interaction, while the S-K upper limits are consistent with the DAMA-compatible region of the WIMP parameter space if the WIMPs annihilate dominantly to $\bbarb$\ and/or $\cbarc$, portions of the DAMA-compatible region can be excluded if WIMP annihilations to $\tautau$ and $\nu\anu$ occur at larger than 10% and $10^{-3}$ levels, respectively. For SD interaction, the restrictions on the possible annihilation channels are much more stringent, essentially ruling out the DAMA-compatible region of the WIMP parameter space if the relatively low-mass ($\sim$ 2 -- 20 GeV) WIMPs under consideration annihilate predominantly to any mixture of $\bbarb$, \ $\cbarc$, \ $\tautau$, \ and $\nu\anu$ final states. The upper limits on the branching fractions of the various annihilation channels obtained here are about a factor of 10 more restrictive than those obtained earlier within the context of the Standard Halo Model.Weakly interacting massive particleSunWIMP annihilationNeutrinoGalaxyBranching ratioDark matterStandard Halo modelDAMA/LIBRAHalo model...
- Using observations in the COSMOS field, we report an intriguing correlation between the star formation activity of massive (~10^{11.4}\msol) central galaxies, their stellar masses, and the large-scale (~10 Mpc) environments of their group-mass (~10^{13.6}\msol) dark matter halos. Probing the redshift range z=[0.2,1.0], our measurements come from two independent sources: an X-ray detected group catalog and constraints on the stellar-to-halo mass relation derived from a combination of clustering and weak lensing statistics. At z=1, we find that the stellar mass in star-forming centrals is a factor of two less than in passive centrals at the same halo mass. This implies that the presence or lack of star formation in group-scale centrals cannot be a stochastic process. By z=0, the offset reverses, probably as a result of the different growth rates of these objects. A similar but weaker trend is observed when dividing the sample by morphology rather than star formation. Remarkably, we find that star-forming centrals at z~1 live in groups that are significantly more clustered on 10 Mpc scales than similar mass groups hosting passive centrals. We discuss this signal in the context of halo assembly and recent simulations, suggesting that star-forming centrals prefer halos with higher angular momentum and/or formation histories with more recent growth; such halos are known to evolve in denser large-scale environments. If confirmed, this would be evidence of an early established link between the assembly history of halos on large scales and the future properties of the galaxies that form inside them.GalaxyStar formationVirial massStellar massCOSMOS surveyStatisticsDark matter haloCross-correlationHalo Occupation DistributionHalo assembly bias...
- A combination of ground-based and spacecraft observations has uncovered two black holes of 10 billion solar masses in the nearby Universe. The finding sheds light on how these cosmic monsters co-evolve with galaxies.Black holeGalaxyAccretionSupermassive black holeStarQuasarA giantsTelescopesSolar massHost galaxy...
- Some of direct dark matter searches reported not only positive signals but also annual modulation of the signal event. However, the parameter spaces have been excluded by other experiments. Isospin violating dark matter solves the contradiction by supposing different coupling to proton and neutron. We study the possibility to test the favored parameter region by isospin violating dark matter model with the future detector of dark matter using the nuclear emulsion. Since the nuclear emulsion detector has directional sensitivity, the detector is expected to examine whether the annual modulations observed other experiments is caused by dark matter or background signals.Dark matterEmulsionIsospinAnnual modulation of dark matter signalIsotopeForm factorEarthCharged particleDark matter modelCoGeNT...
- Galaxy mass and environment are known to play a key role in galaxy evolution: looking at galaxy colors at different redshifts, fixed galaxy mass and environment, offers a powerful diagnosis to disentangle the role of each. In this work, we study the simulateneous dependence of the fraction of blue galaxies fblue on secular evolution, environment and galaxy mass with a well-controlled cluster sample. We are thus able to study the evolution and respective role of the cessation of star formation history (SFH) in clusters due to galaxy mass ("mass quenching") or to environment ("environmental quenching"). We define an homogenous X-ray selected cluster sample (25 clusters with 0 < z < 1 and one cluster at z \sim 2.2), having similar masses and well-defined sizes. Using multicolor photometry and a large spectroscopic sample to calibrate photometric redshifts, we carefully estimate fblue for each cluster at different galaxy mass and cluster-centric distance bins. We then fit with a simple model the dependence of fblue on redshift (z), environment (r/r200) and galaxy mass (M). fblue increases with cluster-centric distance with a slope $1.2^{+0.4}_{-0.3}$, decreases with galaxy mass with a slope $-3.8^{+0.6}_{-0.5}$, and increases with redshift with a slope $3.2^{+0.7}_{-0.5}$. The data also require for the first time a differential evolution with galaxy mass of fblue with redshift, with lower mass galaxies evolving slower by a factor $-4.1^{+1.1}_{-0.9}$. Our study shows that the processes responsible for the cessation of star formation in clusters are effective at all epochs (z<2.2), and more effective in denser environments and for more massive galaxies. We found that the mass and environmental quenchings are separable, that environmental quenching does not change with epoch, and that mass quenching is a dynamical process, i.e. its evolutionary rate is mass-dependent. [Abridged]GalaxyQuenchingStarCluster samplingBlue galaxiesCanada-France-Hawaii Telescope Legacy SurveyMassive galaxiesStar formationSloan Digital Sky SurveyGalactic evolution...
- We studied one of the most X-ray luminous cluster of galaxies in the REFLEX survey, RXC J1504.1-0248 (hereafter R1504; z=0.2153), using XMM-Newton X-ray imaging spectroscopy, VLT/VIMOS optical spectroscopy and WFI optical imaging. The mass distributions were determined using the hydrostatic method with X-ray imaging spectroscopy and dynamical method with optical spectroscopy, respectively, which yield M^{H.E.}_{500}=(5.81+/-0.49)*1.e14Msun and M^{caustic}_{500}=(4.17+/-0.42)*1e14Msun. According to recent calibrations the richness derived mass estimates agree well with the hydrostatic and dynamical mass estimates. The line-of-sight velocities of spectroscopic members reveal a high-velocity (>1000 km/s) group at a projected distance near r^{H.E.}_{500}=(1.18+/-0.03) Mpc south-east of the cluster centroid, which is also indicated in the X-ray two-dimensional (2-D) temperature, density, entropy and pressure maps. The dynamical mass estimate is 80% of the hydrostatic mass estimate at r^{H.E.}_{500}. It can be partially explained by the ~20% scatter in the 2-D pressure map that could be propagated in the hydrostatic mass estimate. The uncertainty of the dynamical mass estimate due to the substructure of the high-velocity group is ~14%. The dynamical mass estimate using blue members is 1.23 times of that using red members. The observed scaling relations of R1504 agree with those for nearby clusters although its stellar mass fraction is rather low.GalaxyHydrostaticsPhase space causticLine of sightBlue galaxiesBrightest cluster galaxyIntra-cluster mediumCluster of galaxiesStellar massMass distribution...
- We estimate the dependence of $\nu_{\mu}$ to $\nu_{e}$ conversion on parameters $\theta_{13}$ and $\delta_{CP}$ for several experimental facilities studying neutrino oscillations. We use the S-Matrix theory to estimate $\bar{\nu_e}$ disappearance and compare estimates based on an older theory being used to extract $\theta_{13}$ from the Double Chooz, Daya Bay, and RENO data, to assist in extracting an accurate value for $\theta_{13}$ from these projects. We use values of $\theta_{13}$ within known limits, and estimate the dependence of $\nu_{\mu}$ - $\nu_{e}$ CP violation (CPV) probability on $\delta_{CP}$ in order to suggest new experiments to measure CPV for neutrinos moving in matter.CP violationNeutrinoDouble Chooz experimentNeutrino oscillationsS-matrixReactor Experiment for Neutrino OscillationNeutrino beamMiniBooNE experimentAntineutrinoElectron neutrino...
- The evolution with time of the abundance of galaxy clusters is very sensitive to the statistical properties of the primordial density perturbations. It can thus be used to probe small deviations from Gaussianity in the initial conditions. The characterization of such deviations would help distinguish between different inflationary scenarios, and provide us with information on physical processes which took place in the early Universe. We have found that when the information contained in the galaxy cluster counts is used to reconstruct the dark energy equation of state as a function of redshift, assuming erroneously that no primordial non-Gaussianities exist, an apparent evolution with time in the effective dark energy equation of state arises,characterized by the appearance of a clear discontinuity.Non-GaussianityCluster of galaxiesDark energyStatisticsPrimordial Non-GaussianitiesMass functionPrimordial density perturbationCosmologyBispectrumWilkinson Microwave Anisotropy Probe...
- We compute the one-loop dispersion relations at finite temperature for quarks, charged leptons and neutrinos in the Minimal Standard Model. The dispersion relations are calculated in two different plasma situations: for a vacuum expectation value $\upsilon$ of the Higgs field $\upsilon \neq 0$ (broken electroweak symmetry) and for $\upsilon=0$ (unbroken electroweak symmetry). The flavour and chiral non-degeneracy of the quasi-particle spectrum is studied. Numerical results show that the thermal effective masses for fermions in the broken phase have a smaller value than those in the unbroken phase. The temperature dependence of the top quark and electron neutrino thermal effective masses is also presented. Gauge invariance of one-loop dispersion relations is studied.Electroweak symmetryThermal effective massStandard ModelCharged leptonHiggs phaseChiralityFlavourTop quarkVacuum expectation valueQuark...
- Future lepton colliders will have a rich top quark physics program which would add to our understanding of this interesting quark and promise an ultimate precision on the experimental knowledge of top-quark mass. We present possible improvements in the understanding of systematic uncertainties for various top-quark mass measurement techniques at the LHC, including projections for running conditions foreseen in the future.Systematic errorLarge Hadron ColliderQCD jetJet energy scaleCurve of marginal stabilityTop quarkTop quark massPileupQuantum chromodynamicsInvariant mass...
- We study, both numerically and analytically, the development of equilibrium after preheating. We show that the process is characterised by the appearance of Kolmogorov spectra and the evolution towards thermal equilibrium follows self-similar dynamics. Simplified kinetic theory gives values for all characteristic exponents which are close to what is observed in lattice simulations. The resulting time for thermalization is long, and temperature at thermalization is low, $T \sim 100$ eV in the simple $\lambda \Phi^4$ inflationary model. Our results allow a straightforward generalization to realistic models.PreheatingSimulationsModel of inflationSelf-similarityLuminosity functionTurbulenceKinetic theoryTemperature...
- We study, analytically and with lattice simulations, the decay of coherent field oscillations and the subsequent thermalization of the resulting stochastic classical wave-field. The problem of reheating of the Universe after inflation constitutes our prime motivation and application of the results. We identify three different stages of these processes. During the initial stage of ``parametric resonance'', only a small fraction of the initial inflaton energy is transferred to fluctuations in the physically relevant case of sufficiently large couplings. A major fraction is transfered in the prompt regime of driven turbulence. The subsequent long stage of thermalization classifies as free turbulence. During the turbulent stages, the evolution of particle distribution functions is self-similar. We show that wave kinetic theory successfully describes the late stages of our lattice calculation. Our analytical results are general and give estimates of reheating time and temperature in terms of coupling constants and initial inflaton amplitude.TurbulenceZero modeInflatonSelf-similarityReheatingKinetic equationPreheatingRelaxationCoupling constantKinetic theory...
- A U-spin relation among four ratios of amplitudes for $D^0 \to \pi^+K^-$, $K^+\pi^-$, $K^+K^-, \pi^+\pi^-$, including first, second and third order U-spin breaking, has been derived recently with a precision of $10^{-3}$. We study effects of new $|\Delta C|=1$ operators on this relation. We find that it is not affected by U-spin scalar operators, including QCD penguin and chromomagnetic dipole operators occurring in supersymmetric and extra-dimensional models. The relation is modified by new $U=1$ operators with a sensitivity characteristic of second order U-spin breaking. Combining this relation with CP asymmetries in $D^0\to K^+K^-, \pi^+\pi^-$ leads to a more solid constraint on $U=1$ operators than from asymmetries alone.AmplitudeCP asymmetryHamiltonianStandard ModelHadronizationSummarizationCP violating phaseQuarkMeson decaysQuadrature...
- ATLAS and CMS HL-LHC prospects for Higgs couplings and rare decays.Rare decayCMS experiment
- We present a study of multiwavelength X-ray and weak lensing scaling relations for a sample of 50 clusters of galaxies. Our analysis combines Chandra and XMM-Newton data using an energy-dependent cross-calibration. After considering a number of scaling relations, we find that gas mass is the most robust estimator of weak lensing mass, yielding 15 +/- 6% intrinsic scatter at r500. The scatter does not change when measured within a fixed physical radius of 1 Mpc. Clusters with small BCG to X-ray peak offsets constitute a very regular population whose members have the same gas mass fractions and whose even smaller <10% deviations from regularity can be ascribed to line of sight geometrical effects alone. Cool-core clusters, while a somewhat different population, also show the same (<10%) scatter in the gas mass-lensing mass relation. There is a good correlation and a hint of bimodality in the plane defined by BCG offset and central entropy (or central cooling time). The pseudo-pressure YX does not discriminate between the more relaxed and less relaxed populations, making it perhaps the more even-handed mass proxy for surveys. Overall, hydrostatic masses underestimate weak lensing masses by 10% on the average at r500; but cool-core clusters are consistent with no bias, while non-cool-core clusters have a large and constant 15-20% bias between r2500 and r500, in agreement with N-body simulations incorporating unthermalized gas. For non-cool-core clusters, the bias correlates well with BCG ellipticity. We also examine centroid shift variance and and power ratios to quantify substructure; these quantities do not correlate with residuals in the scaling relations. Individual clusters have for the most part forgotten the source of their departures from self-similarity.Cluster of galaxiesWeak lensing mass estimateBrightest cluster galaxyCool core galaxy clusterChandra X-ray ObservatoryEntropyCluster mass proxyXMM-NewtonScaling lawWeak lensing...
- In the Standard Model (SM), the Higgs mass around 125 GeV implies that the electroweak vacuum is metastable since the quartic Higgs coupling turns negative at high energies. I point out that an arbitrarily small mixing of the Higgs with a heavy singlet can make the electroweak vacuum completely stable. This is due to a tree level correction to the Higgs mass, which survives in the zero--mixing/heavy--singlet limit. Such a situation is experimentally indistinguishable from the SM, unless the Higgs self--coupling can be measured. As a result, Higgs inflation and its variants can still be viable.Standard ModelHiggs inflationVacuum expectation valueMetastateEigenvalueRenormalization groupColliderLarge Hadron ColliderInflatonDegree of freedom...
- I present a selective survey of the modern phases of quantum matter, and their varieties of many-particle quantum entanglement. I classify the phases as gapped, conformal, or compressible quantum matter. Gapped quantum matter is illustrated by a simple discussion of the Z_2 spin liquid, and connections are made to topological field theories. I discuss how conformal matter is realized at quantum critical points of realistic lattice models, and make connections to a number of experimental systems. Recent progress in our understanding of compressible quantum phases which are not Fermi liquids is summarized. Finally, I discuss how the strongly-coupled phases of quantum matter may be described by gauge-gravity duality. The structure of the large N limit of SU(N) gauge theory, coupled to adjoint fermion matter at non-zero density, suggests aspects of gravitational duals of compressible quantum matter.Fermi surfaceAntiferromagnetEntanglement entropyFermi liquidInsulatorsGauge fieldGauge theoryLong-range entanglementHamiltonianCritical point...
- We discuss relationship between fractional quantum Hall (FQH) states at filling factor $\nu= p/(2p+1)$ and quantum spin chains. This series corresponds to the Jain's states $\nu= p/(2p+1)$ with $m = 1$ where the composite fermion picture is realized. We show that the FQH states with toroidal boundary conditions beyond the thin-torus (TT) limit, can be mapped to effective quantum spin $S = 1$ chains with $p$ spins in each unit cell. We calculate energy gaps and the correlation functions for both the FQH systems and the corresponding effective spin chains, using exact diagonalization and infinite time-evolving block decimation (iTEBD) algorithm. We confirm that the mass gaps of these effective spin chains are decreased as $p$ is increased which is similar to $S = p$ integer Heisenberg chains. These results shed new light on a link between the hierarchy of FQH states and the Haldane conjecture for quantum spin chains.Fractional quantum Hall stateTorusFilling fractionHamiltonianMass gapQuantum Hall EffectUnit cellComposite fermionsLowest Landau LevelCommutant...
- We compute the low energy effective field theory (EFT) expansion for single-field inflationary models that descend from a parent theory containing multiple other scalar fields. By assuming that all other degrees of freedom in the parent theory are sufficiently massive relative to the inflaton, it is possible to derive an EFT valid to arbitrary order in perturbations, provided certain generalized adiabaticity conditions are respected. These conditions permit a consistent low energy EFT description even when the inflaton deviates off its adiabatic minimum along its slowly rolling trajectory. By generalizing the formalism that identifies the adiabatic mode with the Goldstone boson of this spontaneously broken time translational symmetry prior to the integration of the heavy fields, we show that this invariance of the parent theory dictates the entire non-perturbative structure of the descendent EFT. The couplings of this theory can be written entirely in terms of the reduced speed of sound of adiabatic perturbations. The resulting operator expansion is distinguishable from that of other scenarios, such as standard single inflation or DBI inflation. In particular, we re-derive how certain operators can become transiently strongly coupled along the inflaton trajectory, consistent with slow-roll and the validity of the EFT expansion, imprinting features in the primordial power spectrum, and we deduce the relevant cubic operators that imply distinct signatures in the primordial bispectrum which may soon be constrained by observations.Effective field theoryInflatonGoldstone bosonScalar fieldAdiabatic modeEffective actionSlow rollDegree of freedomTranslational invariancePower spectrum...
- The first systematic study of the warm gas (T=10^4-5 K) distribution across a galaxy cluster is presented using multiple background QSOs to the Virgo Cluster. We detect 25 Lya absorbers (N_HI = 10^13.1-15.4 cm^-2) in the Virgo velocity range toward 9 of 12 QSO sightlines observed with COS, with a cluster impact parameter range of 0.25-1.15 Mpc (0.23-1.05Rvir). Including 18 previously STIS or GHRS detected Lya absorbers toward 7 of 11 background QSOs in and around the Virgo Cluster, we establish a sample of 43 absorbers towards a total of 23 background probes for studying the incidence of Lya absorbers in and around the Virgo Cluster. With these absorbers, we find: 1) Warm gas is predominantly in the outskirts of the cluster and avoids the X-ray detected hot ICM. Also, Lya absorption strength increases with a cluster impact parameter. 2) Lya absorbing warm gas traces cold HI emitting gas in the substructures of the Virgo Cluster. 3) Including the absorbers associated with the surrounding substructures, the warm gas covering fraction (100% for N_HI > 10^13.1 cm^-2) is in an agreement with cosmological simulations. We speculate that the observed warm gas is part of large-scale gas flows feeding the cluster both the ICM and galaxies.AbsorbanceGalaxyVirgo ClusterVirial radiusCosmic Origins SpectrographQuasarGalaxy filamentIntra-cluster mediumAbsorptivitySpace Telescope Imaging Spectrograph...
- We present the final results from the XMM-Newton validation follow-up of new Planck cluster candidates. We observed 15 new candidates, detected with signal-to-noise ratios between 4.0 and 6.1 in the 15.5-month nominal Planck survey. The candidates were selected using ancillary data flags derived from the ROSAT All Sky Survey (RASS) and Digitized Sky Survey all-sky maps, with the aim of pushing into the low SZ flux, high- z regime and testing RASS flags as indicators of candidate reliability. 14 new clusters were detected by XMM-Newton, 10 single clusters and 2 double systems. Redshifts from X-ray spectroscopy lie in the range 0.2 to 0.9, with six clusters at z>0.5. Estimated M500 ranges from 2.5 X 10^14 to 8 X 10^14 Msun. We discuss our results in the context of the full XMM validation programme, in which 51 new clusters have been detected. This includes 4 double and 2 triple systems, some of which are chance projections on the sky of clusters at different redshifts. Association with a source from the RASS-Bright Source Catalogue is a robust indicator of candidate reliability, whereas association with a source from the RASS-Faint Source Catalogue does not guarantee that the SZ candidate is a bona fide cluster. Most Planck clusters appear in RASS maps, with a significance greater than 2 sigma being a good indication of a real cluster. The full sample indicates a Planck sensitivity threshold of Y500 ~ 4 X 10^-4 arcmin^2, with indication for Malmquist bias in the YX-Y500 relation below this level. The corresponding mass threshold depends on redshift. Systems with M500 > 5 X 10^14 Msun at z>0.5 are easily detectable with Planck. The newly-detected clusters follow the YX-Y500 relation derived from X-ray selected samples, with no indication of evolution. Compared to X-ray selected clusters, the new SZ clusters are underluminous on average for their mass, at all redshifts.GalaxySignal to noise ratioSloan Digital Sky SurveyMalmquist biasPoint sourceBrightest cluster galaxyPlanck missionStatisticsTriple systemCluster of galaxies...