Showing papers in "Physical Review D in 2015"

Parameter estimation for compact binaries with ground-based gravitational-wave observations using the LALInference software library

Abstract: The Advanced LIGO and Advanced Virgo gravitational-wave (GW) detectors will begin operation in the coming years, with compact binary coalescence events a likely source for the first detections. The gravitational waveforms emitted directly encode information about the sources, including the masses and spins of the compact objects. Recovering the physical parameters of the sources from the GW observations is a key analysis task. This work describes the LALInference software library for Bayesian parameter estimation of compact binary signals, which builds on several previous methods to provide a well-tested toolkit which has already been used for several studies. We show that our implementation is able to correctly recover the parameters of compact binary signals from simulated data from the advanced GW detectors. We demonstrate this with a detailed comparison on three compact binary systems: a binary neutron star, a neutron star–black hole binary and a binary black hole, where we show a cross comparison of results obtained using three independent sampling algorithms. These systems were analyzed with nonspinning, aligned spin and generic spin configurations respectively, showing that consistent results can be obtained even with the full 15-dimensional parameter space of the generic spin configurations. We also demonstrate statistically that the Bayesian credible intervals we recover correspond to frequentist confidence intervals under correct prior assumptions by analyzing a set of 100 signals drawn from the prior. We discuss the computational cost of these algorithms, and describe the general and problem-specific sampling techniques we have used to improve the efficiency of sampling the compact binary coalescence parameter space.

Measurement of the branching ratio of B ¯ →d (∗)τ- ν ¯ τ relative to B ¯ →d (∗) - ν ¯ decays with hadronic tagging at Belle

Abstract: We report a measurement of the branching fraction ratios R(D)(()*()) of (B) over bar -> D-(*())tau(-)(nu) over bar (tau) relative to (B) over bar -> D-(*())l(-)(nu) over barl (where l = e or mu) using the full Belle data sample of 772 x 10(6)B (B) over bar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. The measured values are R(D) = 0.375 +/- 0.064(stat) +/- 0.026(syst) and R(D*) = 0.293 +/- 0.038 (stat) +/- 0.015 (syst). The analysis uses hadronic reconstruction of the tag-side B meson and purely leptonic t decays. The results are consistent with earlier measurements and do not show a significant deviation from the standard model prediction.

Cosmological implications of baryon acoustic oscillation measurements

Abstract: We derive constraints on cosmological parameters and tests of dark energy models from the combination of baryon acoustic oscillation (BAO) measurements with cosmic microwave background (CMB) data and a recent reanalysis of Type Ia supernova (SN) data. In particular, we take advantage of high-precision BAO measurements from galaxy clustering and the Lyman-alpha forest (LyaF) in the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS). Treating the BAO scale as an uncalibrated standard ruler, BAO data alone yield a high confidence detection of dark energy; in combination with the CMB angular acoustic scale they further imply a nearly flat universe. Adding the CMB-calibrated physical scale of the sound horizon, the combination of BAO and SN data into an "inverse distance ladder" yields a measurement of H-0 = 67.3 +/- 1.1 km s(-1) Mpc(-1), with 1.7% precision. This measurement assumes standard prerecombination physics but is insensitive to assumptions about dark energy or space curvature, so agreement with CMB-based estimates that assume a flat Lambda CDM cosmology is an important corroboration of this minimal cosmological model. For constant dark energy (Lambda), our BAO + SN + CMB combination yields matter density Omega(m) = 0.301 +/- 0.008 and curvature Omega(k) = -0.003 +/- 0.003. When we allow more general forms of evolving dark energy, the BAO + SN + CMB parameter constraints are always consistent with flat Lambda CDM values at approximate to 1 sigma. While the overall chi(2) of model fits is satisfactory, the LyaF BAO measurements are in moderate (2-2.5 sigma) tension with model predictions. Models with early dark energy that tracks the dominant energy component at high redshift remain consistent with our expansion history constraints, and they yield a higher H-0 and lower matter clustering amplitude, improving agreement with some low redshift observations. Expansion history alone yields an upper limit on the summed mass of neutrino species, Sigma m(nu) < 0.56 eV (95% confidence), improving to Sigma m(nu) < 0.25 eV if we include the lensing signal in the Planck CMB power spectrum. In a flat Lambda CDM model that allows extra relativistic species, our data combination yields N-eff = 3.43 +/- 0.26; while the LyaF BAO data prefer higher N-eff when excluding galaxy BAO, the galaxy BAO alone favor N-eff approximate to 3. When structure growth is extrapolated forward from the CMB to low redshift, standard dark energy models constrained by our data predict a level of matter clustering that is high compared to most, but not all, observational estimates.

Revised experimental upper limit on the electric dipole moment of the neutron

Abstract: We present for the first time a detailed and comprehensive analysis of the experimental results that set the current world sensitivity limit on the magnitude of the electric dipole moment (EDM) of the neutron. We have extended and enhanced our earlier analysis to include recent developments in the understanding of the effects of gravity in depolarizing ultracold neutrons; an improved calculation of the spectrum of the neutrons; and conservative estimates of other possible systematic errors, which are also shown to be consistent with more recent measurements undertaken with the apparatus. We obtain a net result of dn=−0.21±1.82×10−26 e cm, which may be interpreted as a slightly revised upper limit on the magnitude of the EDM of 3.0×10−26 e cm (90% C.L.) or 3.6×10−26 e cm (95% C.L.).

Numerical simulations of acoustically generated gravitational waves at a first order phase transition

Abstract: We present details of numerical simulations of the gravitational radiation produced by a first order thermal phase transition in the early universe. We confirm that the dominant source of gravitational waves is sound waves generated by the expanding bubbles of the low-temperature phase. We demonstrate that the sound waves have a power spectrum with a power-law form between the scales set by the average bubble separation (which sets the length scale of the fluid flow Lf) and the bubble wall width. The sound waves generate gravitational waves whose power spectrum also has a power-law form, at a rate proportional to Lf and the square of the fluid kinetic energy density. We

Massive Primordial Black Holes from Hybrid Inflation as Dark Matter and the seeds of Galaxies

Abstract: The work of S C is supported by the Return Grant program of the Belgian Science Policy (BELSPO) J G-B acknowledges financial support from the Spanish MINECO under Grants No FPA 2012-39684-C03-02 and No FPA 2013-47983-C03-03 and Consolider-Ingenio “Physics of the Accelerating Universe (PAU)” (CSD2007-00060) We also acknowledge the support from the Spanish MINECO’s “Centro de Excelencia Severo Ochoa” Programme under Grant No SEV-2012-0249

Bekenstein-Hawking Entropy and Strange Metals

Abstract: Black hole horizons have been shown to have characteristic entropies and temperatures. A new investigation shows similarities between the entropy of a black hole and a metallic state of high-temperature superconductors.

Discovering the QCD Axion with Black Holes and Gravitational Waves

Abstract: Advanced LIGO may be the first experiment to detect gravitational waves. Through superradiance of stellar black holes, it may also be the first experiment to discover the QCD axion with decay constant above the grand unification scale. When an axion's Compton wavelength is comparable to the size of a black hole, the axion binds to the black hole, forming a ``gravitational atom.'' Through the superradiance process, the number of axions occupying the bound levels grows exponentially, extracting energy and angular momentum from the black hole. Axions transitioning between levels of the gravitational atom and axions annihilating to gravitons can produce observable gravitational wave signals. The signals are long lasting, monochromatic, and can be distinguished from ordinary astrophysical sources. We estimate up to $\mathcal{O}(1)$ transition events at aLIGO for an axion between $1{0}^{\ensuremath{-}11}$ and $1{0}^{\ensuremath{-}10}\text{ }\text{ }\mathrm{eV}$ and up to $1{0}^{4}$ annihilation events for an axion between $1{0}^{\ensuremath{-}13}$ and $1{0}^{\ensuremath{-}11}\text{ }\text{ }\mathrm{eV}$. In the event of a null search, aLIGO can constrain the axion mass for a range of rapidly spinning black hole formation rates. Axion annihilations are also promising for much lighter masses at future lower-frequency gravitational wave observatories; the rates have large uncertainties, dominated by supermassive black hole spin distributions. Our projections for aLIGO are robust against perturbations from the black hole environment and account for our updated exclusion on the QCD axion of $6\ifmmode\times\else\texttimes\fi{}1{0}^{\ensuremath{-}13}\text{ }\text{ }\mathrm{eV}l{\ensuremath{\mu}}_{a}l2\ifmmode\times\else\texttimes\fi{}1{0}^{\ensuremath{-}11}\text{ }\text{ }\mathrm{eV}$ suggested by stellar black hole spin measurements.

Constraints on the spin-parity and anomalous HVV couplings of the Higgs boson in proton collisions at 7 and 8 TeV

Abstract: The study of the spin-parity and tensor structure of the interactions of the recently discovered Higgs boson is performed using the H to ZZ, Z gamma*, gamma* gamma* to 4 l, H to WW to l nu l nu, and H to gamma gamma decay modes. The full dataset recorded by the CMS experiment during the LHC Run 1 is used, corresponding to an integrated luminosity of up to 5.1 inverse femtobarns at a center-of-mass energy of 7 TeV and up to 19.7 inverse femtobarns at 8 TeV. A wide range of spin-two models is excluded at a 99% confidence level or higher, or at a 99.87% confidence level for the minimal gravity-like couplings, regardless of whether assumptions are made on the production mechanism. Any mixed-parity spin-one state is excluded in the ZZ and WW modes at a greater than 99.999% confidence level. Under the hypothesis that the resonance is a spin-zero boson, the tensor structure of the interactions of the Higgs boson with two vector bosons ZZ, Z gamma, gamma gamma, and WW is investigated and limits on eleven anomalous contributions are set. Tighter constraints on anomalous HVV interactions are obtained by combining the HZZ and HWW measurements. All observations are consistent with the expectations for the standard model Higgs boson with the quantum numbers J[PC]=0[++].

Updated search for spectral lines from Galactic dark matter interactions with pass 8 data from the Fermi Large Area Telescope

Abstract: Dark matter in the Milky Way may annihilate directly into. rays, producing a monoenergetic spectral line. Therefore, detecting such a signature would be strong evidence for dark matter annihilation or decay. We search for spectral lines in the Fermi Large Area Telescope observations of the Milky Way halo in the energy range 200 MeV-500 GeV using analysis methods from our most recent line searches. The main improvements relative to previous works are our use of 5.8 years of data reprocessed with the Pass 8 event-level analysis and the additional data resulting from the modified observing strategy designed to increase exposure of the Galactic center region. We search in five sky regions selected to optimize sensitivity to different theoretically motivated dark matter scenarios and find no significant detections. In addition to presenting the results from our search for lines, we also investigate the previously reported tentative detection of a line at 133 GeV using the new Pass 8 data.

A search for ultralight axions using precision cosmological data

Abstract: Ultralight axions (ULAs) with masses in the range $1{0}^{\ensuremath{-}33}\text{ }\text{ }\mathrm{eV}\ensuremath{\le}{m}_{a}\ensuremath{\le}1{0}^{\ensuremath{-}20}\text{ }\text{ }\mathrm{eV}$ are motivated by string theory and might contribute to either the dark-matter or dark-energy densities of the Universe. ULAs could suppress the growth of structure on small scales, lead to an altered integrated Sachs-Wolfe effect on cosmic microwave-background (CMB) anisotropies, and change the angular scale of the CMB acoustic peaks. In this work, cosmological observables over the full ULA mass range are computed and then used to search for evidence of ULAs using CMB data from the Wilkinson Microwave Anisotropy Probe (WMAP), Planck satellite, Atacama Cosmology Telescope, and South Pole Telescope, as well as galaxy clustering data from the WiggleZ galaxy-redshift survey. In the mass range $1{0}^{\ensuremath{-}32}\text{ }\text{ }\mathrm{eV}\ensuremath{\le}{m}_{a}\ensuremath{\le}1{0}^{\ensuremath{-}25.5}\text{ }\text{ }\mathrm{eV}$, the axion relic-density ${\mathrm{\ensuremath{\Omega}}}_{a}$ (relative to the total dark-matter relic density ${\mathrm{\ensuremath{\Omega}}}_{d}$) must obey the constraints ${\mathrm{\ensuremath{\Omega}}}_{a}/{\mathrm{\ensuremath{\Omega}}}_{d}\ensuremath{\le}0.05$ and ${\mathrm{\ensuremath{\Omega}}}_{a}{h}^{2}\ensuremath{\le}0.006$ at 95% confidence. For ${m}_{a}\ensuremath{\gtrsim}1{0}^{\ensuremath{-}24}\text{ }\text{ }\mathrm{eV}$, ULAs are indistinguishable from standard cold dark matter on the length scales probed, and are thus allowed by these data. For ${m}_{a}\ensuremath{\lesssim}1{0}^{\ensuremath{-}32}\text{ }\text{ }\mathrm{eV}$, ULAs are allowed to compose a significant fraction of the dark energy.

Addressing the LHC flavor anomalies with horizontal gauge symmetries

Abstract: We study the impact of an additional $U(1{)}^{\ensuremath{'}}$ gauge symmetry with flavor-dependent charges for quarks and leptons on the LHC flavor anomalies observed in $B\ensuremath{\rightarrow}{K}^{*}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$, $R(K)=B\ensuremath{\rightarrow}K{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}/B\ensuremath{\rightarrow}K{e}^{+}{e}^{\ensuremath{-}}$, and $h\ensuremath{\rightarrow}\ensuremath{\mu}\ensuremath{\tau}$. In its minimal version with two scalar doublets, the resulting model naturally explains the deviations from the Standard Model observed in $B\ensuremath{\rightarrow}{K}^{*}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ and $R(K)$. The CMS access in $h\ensuremath{\rightarrow}\ensuremath{\mu}\ensuremath{\tau}$ can be explained by introducing a third scalar doublet, which gives rise to a prediction for $\ensuremath{\tau}\ensuremath{\rightarrow}3\ensuremath{\mu}$. We investigate constraints from flavor observables and direct LHC searches for $pp\ensuremath{\rightarrow}{Z}^{\ensuremath{'}}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$. Our model successfully generates the measured fermion-mixing matrices and does not require vectorlike fermions, unlike previous attempts to explain these anomalies.

Search for new phenomena in the dijet mass distribution using pp collision data at √s = 8 TeV with the ATLAS detector

Abstract: Dijet events produced in LHC proton-proton collisions at a center-of-mass energy s√=8 TeV are studied with the ATLAS detector using the full 2012 data set, with an integrated luminosity of 20.3 f ...

A tale of tails: Dark matter interpretations of the Fermi GeV excess in light of background model systematics

Abstract: Several groups have identified an extended excess of gamma rays over the modeled foreground and background emissions towards the Galactic center (GC) based on observations with the Fermi Large Area Telescope. This excess emission is compatible in morphology and spectrum with a telltale sign from dark matter (DM) annihilation. Here, we present a critical reassessment of DM interpretations of the GC signal in light of the foreground and background uncertainties that some of us recently outlaid in Calore et al. (2014). We find that a much larger number of DM models fits the gamma-ray data than previously noted. In particular: (1) In the case of DM annihilation into (b) over barb, we find that even large DM masses up to m(chi) similar or equal to 74 GeV are allowed at p-value > 0.05. (2) Surprisingly, annihilation into nonrelativistic hh gives a good fit to the data. (3) The inverse Compton emission from mu(+)mu(-) with m(chi) similar to 60-70 GeV can also account for the excess at higher latitudes, vertical bar b vertical bar > 2 degrees, both in its spectrum and morphology. We also present novel constraints on a large number of mixed annihilation channels, including cascade annihilation involving hidden sector mediators. Finally, we show that the current limits from dwarf spheroidal observations are not in tension with a DM interpretation when uncertainties on the DM halo profile are accounted for.

Atmospheric and Astrophysical Neutrinos above 1 TeV Interacting in IceCube

Abstract: The IceCube Neutrino Observatory was designed primarily to search for high-energy (TeV-PeV) neutLrinos produced in distant astrophysical objects. A search for. greater than or similar to 100 TeV neutrinos interacting inside the instrumented volume has recently provided evidence for an isotropic flux of such neutrinos. At lower energies, IceCube collects large numbers of neutrinos from the weak decays of mesons in cosmic-ray air showers. Here we present the results of a search for neutrino interactions inside IceCube's instrumented volume between 1 TeV and 1 PeV in 641 days of data taken from 2010-2012, lowering the energy threshold for neutrinos from the southern sky below 10 TeV for the first time, far below the threshold of the previous high-energy analysis. Astrophysical neutrinos remain the dominant component in the southern sky down to a deposited energy of 10 TeV. From these data we derive new constraints on the diffuse astrophysical neutrino spectrum, Phi(v) = 2.06(-0.3)(+0.4) x 10(-18) (E-v = 10(5) GeV)-2.46 +/- 0.12GeV-1 cm(-2) sr(-1) s(-1) for 25 TeV < E-v < 1.4 PeV, as well as the strongest upper limit yet on the flux of neutrinos from charmed-meson decay in the atmosphere, 1.52 times the benchmark theoretical prediction used in previous IceCube results at 90% confidence.

Dissipative hidden sector dark matter

Abstract: The authors propose a simple way of explaining dark matter, without modifying the standard model, by positing a hidden sector containing two stable particles, which interact with the visible sector primarily via gravity. The paper discusses cosmological and astrophysical consequences of such a model, showing that it can provide a satisfactory explanation for a number of dark matter phenomena.

Current status of the Standard Model CKM fit and constraints on $\Delta F=2$ New Physics

Abstract: This letter summarises the status of the global fit of the CKM parameters within the Standard Model performed by the CKMfitter group. Special attention is paid to the inputs for the CKM angles $\alpha$ and $\gamma$ and the status of $B_s\to\mu\mu$ and $B_d\to \mu\mu$ decays. We illustrate the current situation for other unitarity triangles. We also discuss the constraints on generic $\Delta F=2$ New Physics. All results have been obtained with the CKMfitter analysis package, featuring the frequentist statistical approach and using Rfit to handle theoretical uncertainties.

Measurements of neutrino oscillation in appearance and disappearance channels by the T2K experiment with 6.6E20 protons on target

Abstract: We report on measurements of neutrino oscillation using data from the T2K long-baseline neutrino experiment collected between 2010 and 2013. In an analysis of muon neutrino disappearance alone, we find the following estimates and 68% confidence intervals for the two possible mass hierarchies: Normal Hierarchy: $\sin^2\theta_{23}=0.514^{+0.055}_{-0.056}$ and $\Delta m^2_{32}=(2.51\pm0.10)\times 10^{-3}$ eV$^2$/c$^4$ Inverted Hierarchy: $\sin^2\theta_{23}=0.511\pm0.055$ and $\Delta m^2_{13}=(2.48\pm0.10)\times 10^{-3}$ eV$^2$/c$^4$ The analysis accounts for multi-nucleon mechanisms in neutrino interactions which were found to introduce negligible bias. We describe our first analyses that combine measurements of muon neutrino disappearance and electron neutrino appearance to estimate four oscillation parameters and the mass hierarchy. Frequentist and Bayesian intervals are presented for combinations of these parameters, with and without including recent reactor measurements. At 90% confidence level and including reactor measurements, we exclude the region: $\delta_{CP}=[0.15,0.83]\pi$ for normal hierarchy and $\delta_{CP}=[-0.08,1.09]\pi$ for inverted hierarchy. The T2K and reactor data weakly favor the normal hierarchy with a Bayes Factor of 2.2. The most probable values and 68% 1D credible intervals for the other oscillation parameters, when reactor data are included, are: $\sin^2\theta_{23}=0.528^{+0.055}_{-0.038}$ and $|\Delta m^2_{32}|=(2.51\pm0.11)\times 10^{-3}$ eV$^2$/c$^4$.

Searching for dilaton dark matter with atomic clocks

Abstract: We propose an experiment to search for ultralight scalar dark matter (DM) with dilatonic interactions. Such couplings can arise for the dilaton as well as for moduli and axion-like particles in the presence of $CP$ violation. Ultralight dilaton DM acts as a background field that can cause tiny but coherent oscillations in Standard Model parameters such as the fine-structure constant and the proton-electron mass ratio. These minute variations can be detected through precise frequency comparisons of atomic clocks. Our experiment extends current searches for drifts in fundamental constants to the well-motivated high-frequency regime. Our proposed setups can probe scalars lighter than $1{0}^{\ensuremath{-}15}\text{ }\text{ }\mathrm{eV}$ with a discovery potential of dilatonic couplings as weak as $1{0}^{\ensuremath{-}11}$ times the strength of gravity, improving current equivalence principle bounds by up to 8 orders of magnitude. We point out potential $1{0}^{4}$ sensitivity enhancements with future optical and nuclear clocks, as well as possible signatures in gravitational-wave detectors. Finally, we discuss cosmological constraints and astrophysical hints of ultralight scalar DM, and show they are complimentary to and compatible with the parameter range accessible to our proposed laboratory experiments.

Do dark matter axions form a condensate with long-range correlation?

Abstract: The authors investigate the formation of Bose-Einstein condensates from axion dark matter, and it is shown that a homogeneous condensate with long range correlations is unstable when $a\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}c\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}v\phantom{\rule{0}{0ex}}e$ interactions like gravity are taken into account. Instead many Bose-Einstein condensates in form of Bose stars with correlation lengths much below galactic scales are created.

Axion dark matter from topological defects

Abstract: The authors study the cold dark matter axion production in the decay of string-domain wall systems for a scenario where the Peccei-Quinn symmetry remains broken after inflation. Using the most advanced simulations to date, severe constraints for the model parameters (axion mass, decay constant, etc.) are determined, which potentially can be probed in the future experiments.

Dynamical mass ejection from binary neutron star mergers: Radiation-hydrodynamics study in general relativity

Abstract: We perform radiation-hydrodynamics simulations of binary neutron-star mergers in numerical relativity on the Japanese ``K'' supercomputer, taking into account neutrino cooling and heating by an updated leakage-plus-transfer scheme for the first time. Neutron stars are modeled by three modern finite-temperature equations of state (EOS) developed by Hempel and his collaborators. We find that the properties of the dynamical ejecta of the merger such as total mass, average electron fraction, and thermal energy depend strongly on the EOS. Only for a soft EOS (the so-called SFHo), the ejecta mass exceeds $0.01{M}_{\ensuremath{\bigodot}}$. In this case, the distribution of the electron fraction of the ejecta becomes broad due to the shock heating during the merger. These properties are well-suited for the production of the solar-like $r$-process abundance. For the other stiff EOS (DD2 and TM1), for which a long-lived massive neutron star is formed after the merger, the ejecta mass is smaller than $0.01{M}_{\ensuremath{\bigodot}}$, although broad electron-fraction distributions are achieved by the positron capture and the neutrino heating.

Scalar Simplified Models for Dark Matter

Abstract: We introduce a set of minimal simplified models for dark matter interactions with the Standard Model, connecting the two sectors via either a scalar or pseudoscalar particle. These models have a wider regime of validity for dark matter searches at the LHC than the effective field theory approach, while still allowing straightforward comparison to results from noncollider dark matter detection experiments. Such models also motivate dark matter searches in multiple correlated channels. In this paper, we constrain scalar and pseudoscalar simplified models with direct and indirect detection experiments, as well as from existing LHC searches with missing energy plus tops, bottoms, or jets, using the exact loop-induced coupling with gluons. This calculation significantly affects key differential cross sections at the LHC, and must be properly included. We make connections with the Higgs sector, and conclude with a discussion of future searches at the LHC.

Thermodynamics of Black Holes in Massive Gravity

Abstract: We present a class of charged black hole solutions in an (n + 2)-dimensional massive gravity with a negative cosmological constant, and study thermodynamics and phase structure of the black hole solutions both in grand canonical ensemble and canonical ensemble. The black hole horizon can have a positive, zero or negative constant curvature characterized by constant k. By using Hamiltonian approach, we obtain conserved charges of the solutions and nd black hole entropy still obeys the area formula and the gravitational eld equation at the black hole horizon can be cast into the rst law form of black hole thermodynamics. In grand canonical ensemble, we nd that thermodynamics and phase structure depends on the combination k 2 =4 +c2m 2 in the four dimensional case, where is the chemical potential and c2m 2 is the coecient of the second term in the potential associated with graviton mass. When it is positive, the Hawking-Page phase transition can happen, while as it is negative, the black hole is always thermodynamically stable with a positive capacity. In canonical ensemble, the combination turns out to be k +c2m 2 in the four di

Theory of dark matter superfluidity

Abstract: We propose a novel theory of dark matter (DM) superfluidity that matches the successes of the $\mathrm{\ensuremath{\Lambda}}$ cold dark matter ($\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$) model on cosmological scales while simultaneously reproducing the modified Newtonian dynamics (MOND) phenomenology on galactic scales. The DM and MOND components have a common origin, representing different phases of a single underlying substance. DM consists of axionlike particles with mass of order eV and strong self-interactions. The condensate has a polytropic equation of state $P\ensuremath{\sim}{\ensuremath{\rho}}^{3}$ giving rise to a superfluid core within galaxies. Instead of behaving as individual collisionless particles, the DM superfluid is more aptly described as collective excitations. Superfluid phonons, in particular, are assumed to be governed by a MOND-like effective action and mediate a MONDian acceleration between baryonic matter particles. Our framework naturally distinguishes between galaxies (where MOND is successful) and galaxy clusters (where MOND is not); due to the higher velocity dispersion in clusters, and correspondingly higher temperature, the DM in clusters is either in a mixture of superfluid and the normal phase or fully in the normal phase. The rich and well-studied physics of superfluidity leads to a number of observational signatures: an array of low-density vortices in galaxies; merger dynamics that depend on the infall velocity vs phonon sound speed; distinct mass peaks in bulletlike cluster mergers, corresponding to superfluid and normal components; and interference patters in supercritical mergers. Remarkably, the superfluid phonon effective theory is strikingly similar to that of the unitary Fermi gas, which has attracted much excitement in the cold atom community in recent years. The critical temperature for DM superfluidity is of order mK, comparable to known cold atom Bose--Einstein condensates. Identifying a precise cold atom analog would give important insights on the microphysical interactions underlying DM superfluidity. Tantalizingly, it might open the possibility of simulating the properties and dynamics of galaxies in laboratory experiments.

B → D l ν form factors at nonzero recoil and extraction of | V c b |

Abstract: We present a lattice QCD calculation of the $B\ensuremath{\rightarrow}Dl\ensuremath{ u}$ semileptonic decay form factors ${f}_{+}({q}^{2})$ and ${f}_{0}({q}^{2})$ for the entire physical ${q}^{2}$ range. Nonrelativistic QCD bottom quarks and highly improved staggered quark charm and light quarks are employed together with ${N}_{f}=2+1$ MILC gauge configurations. A joint fit to our lattice and BABAR experimental data allows an extraction of the Cabibbo-Kobayashi-Maskawa matrix element $|{V}_{cb}|$. We also determine the phenomenologically interesting ratio $R(D)=\mathcal{B}(B\ensuremath{\rightarrow}D\ensuremath{\tau}{\ensuremath{ u}}_{\ensuremath{\tau}})/\mathcal{B}(B\ensuremath{\rightarrow}Dl{\ensuremath{ u}}_{l})$ ($l=e,\ensuremath{\mu}$). We find $|{V}_{cb}{|}_{\text{excl}}^{B\ensuremath{\rightarrow}D}=0.0402(17)(13)$, where the first error consists of the lattice simulation errors and the experimental statistical error and the second error is the experimental systematic error. For the branching fraction ratio we find $R(D)=0.300(8)$.

Bounds on very low reheating scenarios after Planck

Abstract: We consider the case of very low reheating scenarios [${T}_{\mathrm{RH}}\ensuremath{\sim}\mathcal{O}(\mathrm{MeV})$] with a better calculation of the production of the relic neutrino background (with three-flavor oscillations). At 95% confidence level, a lower bound on the reheating temperature ${T}_{\mathrm{RH}}g4.1\text{ }\text{ }\mathrm{MeV}$ is obtained from big bang nucleosynthesis, while ${T}_{\mathrm{RH}}g4.7\text{ }\text{ }\mathrm{MeV}$ from Planck data (allowing neutrino masses to vary), the most stringent bound on the reheating temperature to date. Neutrino masses as large as 1 eV are possible for very low reheating temperatures.

Singlet-catalyzed electroweak phase transitions and precision Higgs boson studies

Abstract: We update the phenomenology of gauge-singlet extensions of the Standard Model scalar sector and their implications for the electroweak phase transition. Considering the introduction of one real scalar singlet to the scalar potential, we analyze present constraints on the potential parameters from Higgs coupling measurements at the Large Hadron Collider (LHC) and electroweak precision observables for the kinematic regime in which no new scalar decay modes arise. We then show how future precision measurements of Higgs boson signal strengths and the Higgs self-coupling could probe the scalar potential parameter space associated with a strong first-order electroweak phase transition. We illustrate using benchmark precision for several future collider options, including the high-luminosity LHC, the International Linear Collider, Triple-Large Electron-Positron collider, the China Electron-Positron Collider, and a 100 TeV proton-proton collider, such as the Very High Energy LHC or the Super Proton-Proton Collider. For the regions of parameter space leading to a strong first-order electroweak phase transition, we find that there exists considerable potential for observable deviations from purely Standard Model Higgs properties at these prospective future colliders.

Modified teleparallel theories of gravity

Abstract: We investigate modified theories of gravity in the context of teleparallel geometries. It is well known that modified gravity models based on the torsion scalar are not invariant under local Lorentz transformations while modifications based on the Ricci scalar are. This motivates the study of a model depending on the torsion scalar and the divergence of the torsion vector. We derive the teleparallel equivalent of $f(R)$ gravity as a particular subset of these models and also show that this is the unique theory in this class that is invariant under local Lorentz transformation. Furthermore one can show that $f(T)$ gravity is the unique theory admitting second-order field equations.

Search for resonances and quantum black holes using dijet mass spectra in proton-proton collisions at s =8TeV

Abstract: A search for resonances and quantum black holes is performed using the dijet mass spectra measured in proton-proton collisions at s√=8 TeV with the CMS detector at the LHC. The data set corresponds to an integrated luminosity of 19.7 fb^(−1). In a search for narrow resonances that couple to quark-quark, quark-gluon, or gluon-gluon pairs, model-independent upper limits, at 95% confidence level, are obtained on the production cross section of resonances, with masses above 1.2 TeV. When interpreted in the context of specific models the limits exclude string resonances with masses below 5.0 TeV; excited quarks below 3.5 TeV; scalar diquarks below 4.7 TeV; W′ bosons below 1.9 TeV or between 2.0 and 2.2 TeV; Z′ bosons below 1.7 TeV; and Randall-Sundrum gravitons below 1.6 TeV. A separate search is conducted for narrow resonances that decay to final states including b quarks. The first exclusion limit is set for excited b quarks, with a lower mass limit between 1.2 and 1.6 TeV depending on their decay properties. Searches are also carried out for wide resonances, assuming for the first time width-to-mass ratios up to 30%, and for quantum black holes with a range of model parameters. The wide resonance search excludes axigluons and colorons with mass below 3.6 TeV, and color-octet scalars with mass below 2.5 TeV. Lower bounds between 5.0 and 6.3 TeV are set on the masses of quantum black holes.