Showing papers in "Physical Review D in 2013"

Interferometer design of the KAGRA gravitational wave detector

Abstract: KAGRA is a cryogenic interferometric gravitational-wave detector being constructed at the underground site of Kamioka mine in Gifu prefecture, Japan. We performed an optimization of the interferomter design, to achieve the best sensitivity and a stable operation, with boundary conditions of classical noises and under various practical constraints, such as the size of the tunnel or the mirror cooling capacity. Length and alignment sensing schemes for the robust control of the interferometer are developed. In this paper, we describe the detailed design of the KAGRA interferometer as well as the reasoning behind design choices.

Warm dark matter as a solution to the small scale crisis: New constraints from high redshift Lyman-α forest data

Abstract: We present updated constraints on the free-streaming of warm dark matter (WDM) particles derived from an analysis of the Lyman-$\ensuremath{\alpha}$ flux power spectrum measured from high-resolution spectra of 25 $zg4$ quasars obtained with the Keck High Resolution Echelle Spectrometer and the Magellan Inamori Kyocera Echelle spectrograph. We utilize a new suite of high-resolution hydrodynamical simulations that explore WDM masses of 1, 2 and 4 keV (assuming the WDM consists of thermal relics), along with different physically motivated thermal histories. We carefully address different sources of systematic error that may affect our final results and perform an analysis of the Lyman-$\ensuremath{\alpha}$ flux power with conservative error estimates. By using a method that samples the multidimensional astrophysical and cosmological parameter space, we obtain a lower limit ${m}_{\mathrm{WDM}}\ensuremath{\gtrsim}3.3\text{ }\text{ }\mathrm{keV}$ ($2\ensuremath{\sigma}$) for warm dark matter particles in the form of early decoupled thermal relics. Adding the Sloan Digital Sky Survey Lyman-$\ensuremath{\alpha}$ flux power spectrum does not improve this limit. Thermal relics of masses 1, 2 and 2.5 keV are disfavored by the data at about the $9\ensuremath{\sigma}$, $4\ensuremath{\sigma}$ and $3\ensuremath{\sigma}$ C.L., respectively. Our analysis disfavors WDM models where there is a suppression in the linear matter power spectrum at (nonlinear) scales corresponding to $k=10h/\mathrm{Mpc}$ which deviates more than 10% from a Lambda cold dark matter model. Given this limit, the corresponding ``free-streaming mass'' below which the mass function may be suppressed is $\ensuremath{\sim}2\ifmmode\times\else\texttimes\fi{}{10}^{8}{h}^{\ensuremath{-}1}{\mathrm{M}}_{\ensuremath{\bigodot}}$. There is thus very little room for a contribution of the free-streaming of WDM to the solution of what has been termed the small scale crisis of cold dark matter.

Update on scalar singlet dark matter

Abstract: One of the simplest models of dark matter is where a scalar singlet field S comprises some or all of the dark matter and interacts with the standard model through an vertical bar H vertical bar S-2(2) coupling to the Higgs boson. We update the present limits on the model from LHC searches for invisible Higgs decays, the thermal relic density of S, and dark matter searches via indirect and direct detection. We point out that the currently allowed parameter space is on the verge of being significantly reduced with the next generation of experiments. We discuss the impact of such constraints on possible applications of scalar singlet dark matter, including a strong electroweak phase transition, and the question of vacuum stability of the Higgs potential at high scales.

Measurement of an excess of B̄→D(*) τ-ν̄τ decays and implications for charged Higgs bosons

Abstract: The concept for this analysis is to a large degree based on earlier BABAR work and we acknowledge the guidance provided by M. Mazur. The authors consulted with theorists A. Datta, S. Westhoff, S. Fajfer, J. Kamenik, and I. Nisandzic on the calculations of the charged Higgs contributions to the decay rates. We are grateful for the extraordinary contributions of our PEP-II colleagues in achieving the excellent luminosity and machine conditions that have made this work possible. The success of this project also relied critically on the expertise and dedication of the computing organizations that support BABAR. The collaborating institutions wish to thank SLAC for its support and the kind hospitality extended to them. This work is supported by the U.S. Department of Energy and National Science Foundation, the Natural Sciences and Engineering Research Council (Canada), the Commissariat a l'Energie Atomique and Institut National de Physique Nucleaire et de Physique des Particules (France), the Bundesministerium fur Bildung und Forschung and Deutsche Forschungsgemeinschaft (Germany), the Istituto Nazionale di Fisica Nucleare (Italy), the Foundation for Fundamental Research on Matter (Netherlands), the Research Council of Norway, the Ministry of Education and Science of the Russian Federation, Ministerio de Economia y Competitividad (Spain), and the Science and Technology Facilities Council (United Kingdom). Individuals have received support from the Marie-Curie IEF program (European Union) and the A. P. Sloan Foundation (USA).

Mass ejection from the merger of binary neutron stars

Abstract: Numerical-relativity simulations for the merger of binary neutron stars are performed for a variety of equations of state (EOSs) and for a plausible range of the neutron-star mass, focusing primarily on the properties of the material ejected from the system. We find that a fraction of the material is ejected as a mildly relativistic and mildly anisotropic outflow with the typical and maximum velocities $\ensuremath{\sim}0.15--0.25c$ and $\ensuremath{\sim}0.5--0.8c$ (where $c$ is the speed of light), respectively, and that the total ejected rest mass is in a wide range ${10}^{\ensuremath{-}4}--{10}^{\ensuremath{-}2}{M}_{\ensuremath{\bigodot}}$, which depends strongly on the EOS, the total mass, and the mass ratio. The total kinetic energy ejected is also in a wide range between ${10}^{49}$ and ${10}^{51}\text{ }\text{ }\mathrm{ergs}$. The numerical results suggest that for a binary of canonical total mass $2.7{M}_{\ensuremath{\bigodot}}$, the outflow could generate an electromagnetic signal observable by the planned telescopes through the production of heavy-element unstable nuclei via the $r$-process [6,20,21] or through the formation of blast waves during the interaction with the interstellar matter [7], if the EOS and mass of the binary are favorable ones.

Minimal Supergravity Models of Inflation

Abstract: We present a superconformal master action for a class of supergravity models with one arbitrary function defining the Jordan frame. It leads to a gauge-invariant action for a real vector multiplet, which upon gauge fixing describes a massive vector multiplet, or to a dual formulation with a linear multiplet and a massive tensor field. In both cases the models have one real scalar, the inflaton, naturally suited for single-field inflation. Vectors and tensors required by supersymmetry to complement a single real scalar do not acquire vacuum expectation values during inflation, so there is no need to stabilize the extra scalars that are always present in the theories with chiral matter multiplets. The new class of models can describe any inflaton potential that vanishes at its minimum and grows monotonically away from the minimum. In this class of supergravity models, one can fit any desirable choice of inflationary parameters ${n}_{s}$ and $r$.

Beyond Collisionless Dark Matter: Particle Physics Dynamics for Dark Matter Halo Structure

Abstract: Dark matter (DM) self-interactions have important implications for the formation and evolution of structure, from dwarf galaxies to clusters of galaxies. We study the dynamics of self-interacting DM via a light mediator, focusing on the quantum resonant regime where the scattering cross section has a nontrivial velocity dependence. While there are long-standing indications that observations of small scale structure in the Universe are not in accord with the predictions of collisionless DM, theoretical study and simulations of DM self-interactions have focused on parameter regimes with simple analytic solutions for the scattering cross section, with constant or classical velocity (and no angular) dependence. We devise a method that allows us to explore the velocity and angular dependence of self-scattering more broadly, in the strongly coupled resonant and classical regimes where many partial modes are necessary for achieving the result. We map out the entire parameter space of DM self-interactions—and implications for structure observations—as a function of the coupling and the DM and mediator masses. We derive a new analytic formula for describing resonant s-wave scattering. Finally, we show that DM self-interactions can be correlated with observations of Sommerfeld enhancements in DM annihilation through indirect detection experiments.

Sensitivity curves for searches for gravitational-wave backgrounds

Abstract: We propose a graphical representation of detector sensitivity curves for stochastic gravitational-wave backgrounds that takes into account the increase in sensitivity that comes from integrating over frequency in addition to integrating over time. This method is valid for backgrounds that have a power-law spectrum in the analysis band. We call these graphs ``power-law integrated curves.'' For simplicity, we consider cross-correlation searches for unpolarized and isotropic stochastic backgrounds using two or more detectors. We apply our method to construct power-law integrated sensitivity curves for second-generation ground-based detectors such as Advanced LIGO, space-based detectors such as LISA and the Big Bang Observer, and timing residuals from a pulsar timing array. The code used to produce these plots is available at https://dcc.ligo.org/LIGO-P1300115/public for researchers interested in constructing similar sensitivity curves.

The electroweak contributions to (g-2) μ after the Higgs-boson mass measurement

Abstract: The Higgs-boson mass used to be the only unknown input parameter of the electroweak contributions to $(g\ensuremath{-}2{)}_{\ensuremath{\mu}}$ in the Standard Model. It enters at the two-loop level in diagrams with, e.g., top loops, $W$, or $Z$ exchange. We reevaluate these contributions, providing analytic expressions and exact numerical results for the Higgs-boson mass recently measured at the LHC. Our final result for the full Standard Model electroweak contributions is $(153.6\ifmmode\pm\else\textpm\fi{}1.0)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}11}$, where the remaining theory error comes from unknown three-loop contributions and hadronic uncertainties.

Dark matter and pulsar model constraints from Galactic Center Fermi-LAT gamma-ray observations

Abstract: Employing Fermi-LAT gamma-ray observations, several independent groups have found excess extended gamma-ray emission at the Galactic Center (GC). Both annihilating dark matter (DM) or a population of $\ensuremath{\sim}{10}^{3}$ unresolved millisecond pulsars (MSPs) are regarded as well-motivated possible explanations. However, there are significant uncertainties in the diffuse galactic background at the GC. We have performed a revaluation of these two models for the extended gamma-ray source at the GC by accounting for the systematic uncertainties of the Galactic diffuse emission model. We also marginalize over point-source and diffuse background parameters in the region of interest. We show that the excess emission is significantly more extended than a point source. We find that the DM (or pulsar-population) signal is larger than the systematic errors and therefore proceed to determine the sectors of parameter space that provide an acceptable fit to the data. We find that a population of 1000--2000 MSPs with parameters consistent with the average spectral shape of Fermi-LAT measured MSPs is able to fit the GC excess emission. For DM, we find that a pure ${\ensuremath{\tau}}^{+}{\ensuremath{\tau}}^{\ensuremath{-}}$ annihilation channel is not a good fit to the data. But a mixture of ${\ensuremath{\tau}}^{+}{\ensuremath{\tau}}^{\ensuremath{-}}$ and $b\overline{b}$ with a $⟨\ensuremath{\sigma}v⟩$ of order the thermal relic value and a DM mass of around 20 to 60 GeV provides an adequate fit.

CoGeNT: A Search for Low-Mass Dark Matter using p-type Point Contact Germanium Detectors

Abstract: CoGeNT employs $p$-type point-contact (PPC) germanium detectors to search for weakly interacting massive particles (WIMPs). By virtue of its low-energy threshold and ability to reject surface backgrounds, this type of device allows an emphasis on low-mass dark matter candidates (${m}_{\ensuremath{\chi}}\ensuremath{\sim}10\text{ }\text{ }\mathrm{GeV}/{c}^{2}$). We report on the characteristics of the PPC detector presently taking data at the Soudan Underground Laboratory, elaborating on aspects of shielding, data acquisition, instrumental stability, data analysis, and background estimation. A detailed background model is used to investigate the low-energy excess of events previously reported and to assess the possibility of temporal modulations in the low-energy event rate. Extensive simulations of all presently known backgrounds do not provide a viable background explanation for the excess of low-energy events in the CoGeNT data or the previously observed temporal variation in the event rate. Also reported for the first time is a determination of the surface (slow pulse rise time) event contamination in the data as a function of energy. We conclude that the CoGeNT detector technology is well suited to search for the annual modulation signature expected from dark matter particle interactions in the region of WIMP mass and coupling favored by the DAMA/LIBRA results.

Efficient sampling of fast and slow cosmological parameters

Abstract: Physical parameters are often constrained from the data likelihoods using sampling methods. Changing some parameters can be much more computationally expensive (`slow') than changing other parameters (`fast parameters'). I describe a method for decorrelating fast and slow parameters so that parameter sampling in the full space becomes almost as efficient as sampling in the slow subspace when the covariance is well known and the distributions are simple. This gives a large reduction in computational cost when there are many fast parameters. The method can also be combined with a fast 'dragging' method proposed by Neal (2005) that can be more robust and efficient when parameters cannot be fully decorrelated a priori or have more complicated dependencies. I illustrate these methods for the case of cosmological parameter estimation using data likelihoods from the Planck satellite observations with dozens of fast nuisance parameters, and demonstrate a speed up by a factor of five or more. In more complicated cases, especially where the fast subspace is very fast but complex or highly correlated, the fast-slow sampling methods can in principle give arbitrarily large performance gains. The new samplers are implemented in the latest version of the publicly available CosmoMC code.

Understanding the $B\to K^*\mu^+\mu^-$ Anomaly

Abstract: We present a global analysis of the B->K*(->K pi)mu+mu- decay using the recent LHCb measurements of the primary observables P_{1,2} and P'_{4,5,6,8}. Some of them exhibit large deviations with respect to the SM predictions. We explain the observed pattern of deviations through a large New Physics contribution to the Wilson coefficient of the semileptonic operator O9. This contribution has an opposite sign to the SM one, i.e., reduces the size of this coefficient significantly. A good description of data is achieved by allowing for New Physics contributions to the Wilson coefficients C7 and C9 only. We find a 4.5 sigma deviation with respect to the SM prediction, combining the large-recoil B->K*(->K pi)mu+mu- observables with other radiative processes. Once low-recoil observables are included the significance gets reduced to 3.7 sigma. We have tested different sources of systematics, none of them modifying our conclusions significantly. Finally, we propose additional ways of measuring the primary observables through new foldings.

Holographic mutual information is monogamous

Abstract: We identify a special information-theoretic property of quantum field theories with holographic duals: the mutual informations among arbitrary disjoint spatial regions A, B, C obey the inequality I(A∶B∪C)≥I(A∶B)+I(A∶C), provided entanglement entropies are given by the Ryu-Takayanagi formula. Inequalities of this type are known as monogamy relations and are characteristic of measures of quantum entanglement. This suggests that correlations in holographic theories arise primarily from entanglement rather than classical correlations. We also show that the Ryu-Takayanagi formula is consistent with all known general inequalities obeyed by the entanglement entropy, including an infinite set recently discovered by Cadney et al.; this constitutes strong evidence in favor of its validity.

Handbook of vectorlike quarks: Mixing and single production

Abstract: We obtain constraints on the mixing of vectorlike quarks coupling predominantly to the third generation. We consider all (seven) relevant types of vectorlike quarks, individually. The constraints are derived from oblique corrections and $Z\ensuremath{\rightarrow}b\overline{b}$ measurements at the Large Electron-Positron (LEP) Collider and the Stanford Linear Collider. We investigate the implications of these constraints on LHC phenomenology, concerning the decays of the heavy quarks and their single production. We also explore indirect effects of heavy quark mixing in top and bottom couplings. A remarkable effect is the possibility of explaining the anomalous forward-backward asymmetry in $Z\ensuremath{\rightarrow}b\overline{b}$ at the LEP with a hypercharge $\ensuremath{-}5/6$ doublet. We also study the impact of the new quarks on single Higgs production at the LHC and Higgs decay.

Testing the hadronuclear origin of PeV neutrinos observed with IceCube

Abstract: We consider implications of the IceCube signal for hadronuclear ($pp$) scenarios of neutrino sources such as galaxy clusters/groups and star-forming galaxies. Since the observed neutrino flux is comparable to the diffuse $\ensuremath{\gamma}$-ray background flux obtained by Fermi, we place new, strong upper limits on the source spectral index, $\ensuremath{\Gamma}\ensuremath{\lesssim}2.1--2.2$. In addition, the new IceCube data imply that these sources contribute at least 30%--40% of the diffuse $\ensuremath{\gamma}$-ray background in the 100 GeV range and even $\ensuremath{\sim}100%$ for softer spectra. Our results, which are insensitive to details of the $pp$ source models, are one of the first strong examples of the multimessenger approach combining the measured neutrino and $\ensuremath{\gamma}$-ray fluxes. The $pp$ origin of the IceCube signal can further be tested by constraining $\ensuremath{\Gamma}$ with sub-PeV neutrino observations, by unveiling the sub-TeV diffuse $\ensuremath{\gamma}$-ray background and by observing such $pp$ sources with TeV $\ensuremath{\gamma}$-ray detectors. We also discuss specific $pp$ source models with a multi-PeV neutrino break/cutoff, which are consistent with the current IceCube data.

Reentrant phase transitions in rotating anti–de Sitter black holes

Abstract: Introduction In view of the AdS/CFT correspondence, phase transitions in asymptotically AdS black holes allow for a dual interpretation in the thermal conformal field theory (CFT) living on the AdS boundary—the principal example being the well known radiation/Schwarzschild-AdS black hole Hawking–Page transition [1] which can be interpreted as a confinement/deconfinement phase transition in the dual quark gluon plasma [2] Charged [3–6] and rotating [7, 8] asymptotically AdS back holes possess an interesting feature—they allow for a first order small-blackhole/large-black-holephase (SBH/LBH) transition which is in many ways reminiscent of the liquid/gas transition of the Van der Waals fluid This superficial analogy was recently found more intriguing [9] by considering a thermodynamic analysis in an extended phase space where the cosmological constant is identified with thermodynamic pressure and its variations are included in the first law of black hole thermodynamics This notion emerges from geometric derivations of the Smarr formula [10] that i) imply the mass of an AdS black hole should be interpreted as the enthalpy of the spacetime and ii) allow for a computation of the conjugate thermodynamic volume Intensive and extensive quantities are now properly identified [9] and the SBH/LBH transition can be understood as a liquid/gas phase transition by employing Maxwell’s equal area law to the P V diagram Coexistence lines and critical exponents are then seen to match those of a Van der Waals fluid In this paper we report the finding of an interesting phenomena, observed previously in multicomponent fluids, eg, [11], of black hole reentrant phase transitions (RPTs) A system undergoes an RPT if a monotonic variation of any thermodynamic quantity results in two (or more) phase transitions such that the final state is macroscopically similar to the initial state We find for a certain range of pressures (and a given angular momentum) that a monotonic lowering of the temperature yields a large-small-large black hole transition, where we refer to the latter ‘large’ state as an intermediate black hole (IBH) This situation is accompanied by a discontinuity in the global minimum of the Gibbs free energy, referred to as a zeroth-order phase transition, a phenomenon seen in superfluidity and superconductivity [12], and recently for Born–Infeld black holes [13] We find the RPT to be generic for all rotating AdS black holes in d � 6 dimen

Dark Matter, Baryogenesis and Neutrino Oscillations from Right Handed Neutrinos

Abstract: We show that, leaving aside accelerated cosmic expansion, all experimental data in high energy physics that are commonly agreed to require physics beyond the Standard Model can be explained when completing the model by three right-handed neutrinos that can be searched for using present-day experimental techniques. The model that realizes this scenario is known as the Neutrino Minimal Standard Model (nu MSM). In this article we give a comprehensive summary of all known constraints in the nu MSM, along with a pedagogical introduction to the model. We present the first complete quantitative study of the parameter space of the model where no physics beyond the nu MSM is needed to simultaneously explain neutrino oscillations, dark matter, and the baryon asymmetry of the Universe. The key new point of our analysis is leptogenesis after sphaleron freeze-out, which leads to resonant dark matter production, thus evading the constraints on sterile neutrino dark matter from structure formation and x-ray searches. This requires one to track the time evolution of left-and right-handed neutrino abundances from hot big bang initial conditions down to temperatures below the QCD scale. We find that the interplay of resonant amplifications, CP-violating flavor oscillations, scatterings, and decays leads to a number of previously unknown constraints on the sterile neutrino properties. We furthermore reanalyze bounds from past collider experiments and big bang nucleosynthesis in the face of recent evidence for a nonzero neutrino mixing angle theta(13). We combine all our results with existing constraints on dark matter properties from astrophysics and cosmology. Our results provide a guideline for future experimental searches for sterile neutrinos. A summary of the constraints on sterile neutrino masses and mixings has appeared in Canetti et al. [Phys. Rev. Lett. 110, 061801 (2013)]. In this article we provide all details of our calculations and give constraints on other model parameters.

Radial coordinates for conformal blocks

Abstract: We develop the theory of conformal blocks in ${\mathrm{CFT}}_{d}$ expressing them as power series with Gegenbauer polynomial coefficients. Such series have a clear physical meaning when the conformal block is analyzed in radial quantization: individual terms describe contributions of descendants of a given spin. Convergence of these series can be optimized by a judicious choice of the radial quantization origin. We argue that the best choice is to insert the operators symmetrically. We analyze in detail the resulting ``$\ensuremath{\rho}$-series'' and show that it converges much more rapidly than for the commonly used variable $z$. We discuss how these conformal block representations can be used in the conformal bootstrap. In particular, we use them to derive analytically some bootstrap bounds whose existence was previously found numerically.

New Observables for Direct Detection of Axion Dark Matter

Abstract: We propose new signals for the direct detection of ultralight dark matter such as the axion. Axion or axionlike particle dark matter may be thought of as a background, classical field. We consider couplings for this field which give rise to observable effects including a nuclear electric dipole moment, and axial nucleon and electron moments. These moments oscillate rapidly with frequencies accessible in the laboratory, $\ensuremath{\sim}$ kilohertz to gigahertz, given by the dark matter mass. Thus, in contrast to WIMP detection, instead of searching for the hard scattering of a single dark matter particle, we are searching for the coherent effects of the entire classical dark matter field. We calculate current bounds on such time-varying moments and consider a technique utilizing NMR methods to search for the induced spin precession. The parameter space probed by these techniques is well beyond current astrophysical limits and significantly extends laboratory probes. Spin precession is one way to search for these ultralight particles, but there may well be many new types of experiments that can search for dark matter using such time-varying moments.

Generic conditions for stable hybrid stars

Abstract: We study the mass-radius curve of hybrid stars, assuming a single first-order phase transition between nuclear and quark matter, with a sharp interface between the quark matter core and nuclear matter mantle. We use a generic parametrization of the quark matter equation of state, which has a constant, i.e. density-independent, speed of sound. We argue that this parametrization provides a framework for comparison and empirical testing of models of quark matter. We obtain the phase diagram of possible forms of the hybrid star mass-radius relation, where the control parameters are the transition pressure, energy density discontinuity, and the quark matter speed of sound. We find that this diagram is sensitive to the quark matter parameters but fairly insensitive to details of the nuclear matter equation of state (EoS). We calculate the maximum hybrid star mass as a function of the parameters of the quark matter EoS, and find that there are reasonable values of those parameters that give rise to hybrid stars with mass above $2{M}_{\ensuremath{\bigodot}}$.

Flavor-phenomenology of two-Higgs-doublet models with generic Yukawa structure

Abstract: In this article, we perform an extensive study of flavor observables in a two-Higgs-doublet model with generic Yukawa structure (of type III). This model is interesting not only because it is the decoupling limit of the minimal supersymmetric standard model but also because of its rich flavor phenomenology which also allows for sizable effects not only in flavor-changing neutral-current (FCNC) processes but also in tauonic $B$ decays. We examine the possible effects in flavor physics and constrain the model both from tree-level processes and from loop observables. The free parameters of the model are the heavy Higgs mass, $\mathrm{tan} \ensuremath{\beta}$ (the ratio of vacuum expectation values) and the ``nonholomorphic'' Yukawa couplings ${ϵ}_{ij}^{f}(f=u,d,\ensuremath{\ell})$. In our analysis we constrain the elements ${ϵ}_{ij}^{f}$ in various ways: In a first step we give order of magnitude constraints on ${ϵ}_{ij}^{f}$ from 't Hooft's naturalness criterion, finding that all ${ϵ}_{ij}^{f}$ must be rather small unless the third generation is involved. In a second step, we constrain the Yukawa structure of the type-III two-Higgs-doublet model from tree-level FCNC processes (${B}_{s,d}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$, ${K}_{L}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$, ${\overline{D}}^{0}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$, $\ensuremath{\Delta}F=2$ processes, ${\ensuremath{\tau}}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{\ensuremath{-}}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$, ${\ensuremath{\tau}}^{\ensuremath{-}}\ensuremath{\rightarrow}{e}^{\ensuremath{-}}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ and ${\ensuremath{\mu}}^{\ensuremath{-}}\ensuremath{\rightarrow}{e}^{\ensuremath{-}}{e}^{+}{e}^{\ensuremath{-}}$) and observe that all flavor off-diagonal elements of these couplings, except ${ϵ}_{32,31}^{u}$ and ${ϵ}_{23,13}^{u}$, must be very small in order to satisfy the current experimental bounds. In a third step, we consider Higgs mediated loop contributions to FCNC processes [$b\ensuremath{\rightarrow}s(d)\ensuremath{\gamma}$, ${B}_{s,d}$ mixing, $K\ensuremath{-}\overline{K}$ mixing and $\ensuremath{\mu}\ensuremath{\rightarrow}e\ensuremath{\gamma}$] finding that also ${ϵ}_{13}^{u}$ and ${ϵ}_{23}^{u}$ must be very small, while the bounds on ${ϵ}_{31}^{u}$ and ${ϵ}_{32}^{u}$ are especially weak. Furthermore, considering the constraints from electric dipole moments we obtain constrains on some parameters ${ϵ}_{ij}^{u,\ensuremath{\ell}}$. Taking into account the constraints from FCNC processes we study the size of possible effects in the tauonic $B$ decays ($B\ensuremath{\rightarrow}\ensuremath{\tau}\ensuremath{ u}$, $B\ensuremath{\rightarrow}D\ensuremath{\tau}\ensuremath{ u}$ and $B\ensuremath{\rightarrow}{D}^{*}\ensuremath{\tau}\ensuremath{ u}$) as well as in ${D}_{(s)}\ensuremath{\rightarrow}\ensuremath{\tau}\ensuremath{ u}$, ${D}_{(s)}\ensuremath{\rightarrow}\ensuremath{\mu}\ensuremath{ u}$, $K(\ensuremath{\pi})\ensuremath{\rightarrow}e\ensuremath{ u}$, $K(\ensuremath{\pi})\ensuremath{\rightarrow}\ensuremath{\mu}\ensuremath{ u}$ and $\ensuremath{\tau}\ensuremath{\rightarrow}K(\ensuremath{\pi})\ensuremath{ u}$ which are all sensitive to tree-level charged Higgs exchange. Interestingly, the unconstrained ${ϵ}_{32,31}^{u}$ are just the elements which directly enter the branching ratios for $B\ensuremath{\rightarrow}\ensuremath{\tau}\ensuremath{ u}$, $B\ensuremath{\rightarrow}D\ensuremath{\tau}\ensuremath{ u}$ and $B\ensuremath{\rightarrow}{D}^{*}\ensuremath{\tau}\ensuremath{ u}$. We show that they can explain the deviations from the SM predictions in these processes without fine-tuning. Furthermore, $B\ensuremath{\rightarrow}\ensuremath{\tau}\ensuremath{ u}$, $B\ensuremath{\rightarrow}D\ensuremath{\tau}\ensuremath{ u}$ and $B\ensuremath{\rightarrow}{D}^{*}\ensuremath{\tau}\ensuremath{ u}$ can even be explained simultaneously. Finally, we give upper limits on the branching ratios of the lepton flavor-violating neutral $B$ meson decays (${B}_{s,d}\ensuremath{\rightarrow}\ensuremath{\mu}e$, ${B}_{s,d}\ensuremath{\rightarrow}\ensuremath{\tau}e$ and ${B}_{s,d}\ensuremath{\rightarrow}\ensuremath{\tau}\ensuremath{\mu}$) and correlate the radiative lepton decays ($\ensuremath{\tau}\ensuremath{\rightarrow}\ensuremath{\mu}\ensuremath{\gamma}$, $\ensuremath{\tau}\ensuremath{\rightarrow}e\ensuremath{\gamma}$ and $\ensuremath{\mu}\ensuremath{\rightarrow}e\ensuremath{\gamma}$) to the corresponding neutral current lepton decays (${\ensuremath{\tau}}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{\ensuremath{-}}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$, ${\ensuremath{\tau}}^{\ensuremath{-}}\ensuremath{\rightarrow}{e}^{\ensuremath{-}}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ and ${\ensuremath{\mu}}^{\ensuremath{-}}\ensuremath{\rightarrow}{e}^{\ensuremath{-}}{e}^{+}{e}^{\ensuremath{-}}$). A detailed Appendix contains all relevant information for the considered processes for general scalar-fermion-fermion couplings.

Global fit to Higgs signal strengths and couplings and implications for extended Higgs sectors

Abstract: The most recent LHC data have provided a considerable improvement in the precision with which various Higgs production and decay channels have been measured. Using all available public results from ATLAS, CMS and the Tevatron, we derive for each final state the combined confidence level contours for the signal strengths in the (gluon fusion + ttH associated production) versus (vector boson fusion + VH associated production) space. These “combined signal strength ellipses” can be used in a simple, generic way to constrain a very wide class of New Physics models in which the couplings of the Higgs boson deviate from the Standard Model prediction. Here, we use them to constrain the reduced couplings of the Higgs boson to up-quarks, down-quarks/leptons and vector boson pairs. We also consider New Physics contributions to the loop-induced gluon-gluon and photon-photon couplings of the Higgs, as well as invisible/unseen decays. Finally, we apply our fits to some simple models with an extended Higgs sector, in particular to Two-Higgs-Doublet models of Type I and Type II, the Inert Doublet model, and the Georgi–Machacek triplet Higgs model.

Extended phase space thermodynamics and P-V criticality of black holes with a nonlinear source

Abstract: In this paper, we consider the solutions of Einstein gravity in the presence of a generalized Maxwell theory, namely power Maxwell invariant. First, we investigate the analogy of nonlinear charged black hole solutions with the Van der Waals liquid–gas system in the extended phase space where the cosmological constant appear as pressure. Then, we plot isotherm P-V diagram and study the thermodynamics of AdS black hole in the (grand canonical) canonical ensemble in which (potential) charge is fixed at infinity. Interestingly, we find the phase transition occurs in the both of canonical and grand canonical ensembles in contrast to Reissner-Nordstrom black hole in Maxwell theory which only admits canonical ensemble phase transition. Moreover, we calculate the critical exponents and find their values are the same as those in mean field theory. Besides, we find in the grand canonical ensembles universal ratio PcvcTc is independent of spacetime dimensions.

Threshold of primordial black hole formation

Abstract: Based on a physical argument, we derive a new analytic formula for the amplitude of density perturbation at the threshold of primordial black hole formation in the Universe dominated by a perfect fluid with the equation of state $p=w\ensuremath{\rho}{c}^{2}$ for $w\ensuremath{\ge}0$. The formula gives ${\ensuremath{\delta}}_{Hc}^{\mathrm{UH}}={sin }^{2}[\ensuremath{\pi}\sqrt{w}/(1+3w)]$ and ${\stackrel{\texttildelow{}}{\ensuremath{\delta}}}_{c}=[3(1+w)/(5+3w)]{sin }^{2}[\ensuremath{\pi}\sqrt{w}/(1+3w)]$, where ${\ensuremath{\delta}}_{Hc}^{\mathrm{UH}}$ and ${\stackrel{\texttildelow{}}{\ensuremath{\delta}}}_{c}$ are the amplitude of the density perturbation at the horizon crossing time in the uniform Hubble slice and the amplitude measure used in numerical simulations, respectively, while the conventional one gives ${\ensuremath{\delta}}_{Hc}^{\mathrm{UH}}=w$ and ${\stackrel{\texttildelow{}}{\ensuremath{\delta}}}_{c}=3w(1+w)/\phantom{\rule{0ex}{0ex}}(5+3w)$. Our formula shows a much better agreement with the result of recent numerical simulations both qualitatively and quantitatively than the conventional formula. For a radiation fluid, our formula gives ${\ensuremath{\delta}}_{Hc}^{\mathrm{UH}}={sin }^{2}(\sqrt{3}\ensuremath{\pi}/6)\ensuremath{\simeq}0.6203$ and ${\stackrel{\texttildelow{}}{\ensuremath{\delta}}}_{c}=(2/3){sin }^{2}(\sqrt{3}\ensuremath{\pi}/6)\ensuremath{\simeq}0.4135$. We also discuss the maximum amplitude and the cosmological implications of the present result.

I-Love-Q Relations in Neutron Stars and their Applications to Astrophysics, Gravitational Waves and Fundamental Physics

Abstract: The exterior gravitational field of a slowly rotating neutron star can be characterized by its multipole moments, the first few being the neutron star mass, moment of inertia, and quadrupole moment to quadratic order in spin. In principle, all of these quantities depend on the neutron star's internal structure, and thus, on unknown nuclear physics at supranuclear energy densities, all of which is usually parametrized through an equation of state. We here find relations between the moment of inertia, the Love numbers and the quadrupole moment (I-Love-Q relations) that do not depend sensitively on the neutron star's internal structure. Such universality may arise for two reasons: (i) these relations depend most sensitively on the internal structure far from the core, where all realistic equations of state mostly approach each other; (ii) as the neutron star compactness increases, the I-Love-Q trio approaches that of a black hole, which does not have an internal-structure dependence. Three important consequences derive from these I-Love-Q relations. On an observational astrophysics front, the measurement of a single member of the I-Love-Q trio would automatically provide information about the other two, even when the latter may not be observationally accessible. On a gravitational-wave front, the I-Love-Q relations break the degeneracy between the quadrupole moment and the neutron star spins in binary inspiral waveforms, allowing second-generation ground-based detectors to determine the (dimensionless) averaged spin to $\mathcal{O}(10)%$, given a sufficiently large signal-to-noise ratio detection. On a fundamental physics front, the I-Love-Q relations allow for tests of general relativity in the neutron star strong field that are both theory and internal-structure independent. As an example, by combining gravitational-wave and electromagnetic observations, one may constrain dynamical Chern-Simons gravity in the future by more than six orders of magnitude more stringently than Solar System and table-top constraints.

Universal Resistivity from Holographic Massive Gravity

Abstract: Massive gravity provides a holographic model for theories exhibiting momentum dissipation. We provide an analytic expression for the DC conductivity. The result is universal, depending only on properties of the infrared horizon, and holds at finite temperature and charge density. In addition, we provide a derivation of black hole thermodynamics in holographic massive gravity and show that the resulting physics is sensible.

Testing leptoquark models in $\bar B \to D^{(*)} \tau \bar\nu$

Abstract: We study potential new physics effects in the B¯→D(*)τν¯ decays. As a particular example of new physics models, we consider the class of leptoquark models and put the constraints on the leptoquark couplings using the recently measured ratios R(D(*))=B(B¯→D(*)τν¯)/B(B¯→D(*)μν¯). For consistency, some of the constraints are compared with the ones coming from the current experimental bound on B(B→Xsνν¯). In order to discriminate various new physics scenarios, we examine the correlations between different observables that can be measured in the future.

Thermodynamic Volumes and Isoperimetric Inequalities for de Sitter Black Holes

Abstract: We consider the thermodynamics of rotating and charged asymptotically de Sitter (dS) black holes. Using Hamiltonian perturbation-theory techniques, we derive three different first-law relations including variations in the cosmological constant, and associated Smarr formulas that are satisfied by such spacetimes. Each first law introduces a different thermodynamic volume conjugate to the cosmological constant. We examine the relation between these thermodynamic volumes and associated geometric volumes in a number of examples, including Kerr-dS black holes in all dimensions and Kerr-Newman-dS black holes in D=4. We also show that the Chong-Cvetic-Lu-Pope solution of D=5 minimal supergravity—analytically continued to positive cosmological constant—describes black hole solutions of the Einstein-Chern-Simons theory and include such charged asymptotically de Sitter black holes in our analysis. In all these examples we find that the particular thermodynamic volume associated with the region between the black hole and cosmological horizons is equal to the naive geometric volume. Isoperimetric inequalities, which hold in the examples considered, are formulated for the different thermodynamic volumes and conjectured to remain valid for all asymptotically de Sitter black holes. In particular, in all examples considered, we find that for a fixed volume of the observable universe, the entropy is increased by adding black holes. We conjecture that this is true in general.

Neutrinos with Lorentz-violating operators of arbitrary dimension

Abstract: The theoretical description of fermions in the presence of Lorentz and $CPT$ violation is developed. We classify all Lorentz- and $CPT$-violating and invariant terms in the quadratic Lagrange density for a Dirac fermion, including operators of arbitrary mass dimension. The exact dispersion relation is obtained in closed and compact form, and projection operators for the spinors are derived. The Pauli Hamiltonians for particles and antiparticles are extracted, and observable combinations of operators are identified. We characterize and enumerate the coefficients for Lorentz violation for any operator mass dimension via a decomposition using spin-weighted spherical harmonics. The restriction of the general theory to various special cases is presented, including isotropic models, the nonrelativistic and ultrarelativistic limits, and the minimal Standard-Model Extension. Expressions are derived in several limits for the fermion dispersion relation, the associated fermion group velocity, and the fermion spin-precession frequency. We connect the analysis to some other formalisms and use the results to extract constraints from astrophysical observations on isotropic ultrarelativistic spherical coefficients for Lorentz violation.