This paper studies a class of $D=n+2(\ge 6)$ dimensional solutions to Lovelock gravity that is described by the warped product of a two-dimensional Lorentzian metric and an $n$-dimensional Einstein space. Assuming that the angular part of the stress-energy tensor is proportional to the Einstein metric, it turns out that the Weyl curvature of an Einstein space must obey two kinds of algebraic conditions. We present some exact solutions satisfying these conditions. We further define the quasilocal mass corresponding to the Misner-Sharp mass in general relativity. It is found that the quasilocal mass is constructed out of the Kodama flux and satisfies the unified first law and the monotonicity property under the dominant energy condition. Making use of the quasilocal mass, we show Birkhoff’s theorem and address various aspects of dynamical black holes characterized by trapping horizons.

We discuss the parametrized post-Newtonian (PPN) limit of Horndeski’s theory of gravity, also known under the name generalized G-inflation or ${\mathrm{G}}^2$-inflation, which is the most general scalar-tensor theory of gravity with at most second-order field equations in four dimensions. We derive conditions on the action for the validity of the post-Newtonian limit. For the most general class of theories consistent with these conditions we calculate the PPN parameters $\gamma (r)$ and $\beta (r)$, which in general depend on the interaction distance $r$ between the gravitating mass and the test mass. For a more restricted class of theories, in which the scalar field is massless, we calculate the full set of PPN parameters. It turns out that in this restricted case all parameters are constants and that the only parameters potentially deviating from observations are $\gamma$ and $\beta$. We finally apply our results to a number of example theories, including Galileons and different models of Higgs inflation.

Within the framework of the “brick wall model,” a novel method is developed to compute the contributions of a scalar field to the thermodynamic quantities of black holes. The relations between (transverse) momenta and frequencies in Rindler space are determined numerically with high accuracy and analytically with an accuracy of better than 10% and are compared with the corresponding quantities in Minkowski space. In conflict with earlier results, the thermodynamic properties of black holes turn out to be those of a low-temperature system. The resulting discrepancy for partition function and entropy by 2 orders of magnitude is analyzed in detail. In the final part we carry out the analogous studies for scalar fields in de Sitter space and thereby confirm that our method applies also to the important case of spherically symmetric spaces.

The potential of precision spectroscopy as a tool in systematic searches for effects of Lorentz and $CPT$ violation is investigated. Systems considered include hydrogen, antihydrogen, deuterium, positronium, and hydrogen molecules and molecular ions. Perturbative shifts in energy levels and key transition frequencies are derived, allowing for Lorentz-violating operators of arbitrary mass dimensions. Observable effects are deduced from various direct measurements, sidereal and annual variations, comparisons among species, and gravitational responses. We use existing data to place new and improved constraints on nonrelativistic coefficients for Lorentz and $CPT$ violation, and we provide estimates for the future attainable reach in direct spectroscopy of the various systems or tests with hydrogen and deuterium masers. The results reveal prospective sensitivities to many coefficients unmeasured to date, along with potential improvements of a billionfold or more over certain existing results.

We discuss the impact of additional two-body decays of the right-handed neutrino into a light charged Higgs state on the dilepton plus dijet cross sections from resonant $W^{\prime }$ production. We consider in particular a supersymmetric left-right symmetric model which predicts such a light charged Higgs boson. We demonstrate that the $eejj$ excess as measured by CMS can be explained best if the $W^{\prime }$ also has decay modes into Higgsino-like charginos and neutralinos with masses of a few hundred GeV. Provided that this excess is confirmed, the model predicts also one right-handed neutrino with a mass below 200 GeV as well as a doubly charged Higgs boson which should be discovered at the LHC in the near future.

We examine the constraints coming from incorporating the full Standard Model gauge symmetry into the effective field theory description of flavor processes, using semileptonic decays as paradigmatic examples. Depending on the dynamics triggering electroweak symmetry breaking, different patterns of correlations between the Wilson coefficients arise. Interestingly, this implies that flavor experiments are capable of shedding light upon the nature of the Higgs boson without actually requiring Higgs final states. Furthermore, the observed correlations can simplify model-independent analyses of these decays.

Within two Higgs doublet models, it is possible that the current vacuum is not the global minimum, in which case it could possibly decay at a later stage. We discuss the tree-level conditions which must be obeyed by the most general scalar potential in order to preclude that possibility. We propose a new procedure which is not only more general but also easier to implement than the previously published one, including $CP$ conserving as well as $CP$ violating scalar sectors. We illustrate these conditions within the context of the $Z_2$ model, softly broken by a complex, $CP$ violating parameter.

We investigate $W^{\prime }$ interpretations for the ATLAS 2 TeV diboson anomalies. The roles of the unitarity sum rules, which ensure the perturbativity of the longitudinal vector boson scattering amplitudes, are emphasized. We find the unitarity sum rules and the custodial symmetry are powerful enough to predict various nontrivial relations among $WW{Z}^{\prime }$, $WZ{W}^{\prime }$, $WWh$, $W{W}^{\prime }h$ and $Z{Z}^{\prime }h$ coupling strengths in a model independent manner. We also perform surveys in the general parameter space of $W^{\prime }$ models and find the ATLAS 2 TeV diboson anomalies may be interpreted as a $W^{\prime }$ particle of the three-site moose model, i.e., a Kaluza-Klein like particle in a deconstructed extra dimension model. It is also shown that the nonstandard-model-like Higgs boson is favored by the present data to interpret the ATLAS diboson anomalies as the consequences of the $W^{\prime }$ and $Z^{\prime }$ bosons.

To obtain high-quality results from lattice QCD, it is important to use operators that produce good signals for the quantities of interest. Free-form smearing is a powerful tool that helps to accomplish that goal. The present work introduces a new implementation of free-form smearing that maintains its usefulness and reduces its computational time dramatically. Applications to the mass spectrum of $B$, $B_s$, $B_c$ and bottomonium mesons show the effectiveness of the method. Results are compared with other lattice QCD studies and with experimental data where available. The present work includes the first lattice QCD exploration for some of these mesons.

The $\eta -{\eta }^{\prime }$ mixing mass term due to the derivative coupling $SU(3)\times SU(3)$ symmetry breaking term, produces an additional momentum-dependent pole term for processes with ${\eta }^{\prime }$ but is suppressed in the $\eta$ amplitude by a factor $m_{\eta }^2/m_{{\eta }^{\prime }}^2$. This seems to be the origin of the two-angle description of the pseudoscalar decay constants used in the literature. In this paper, by diagonalizing both the mixing mass term and the momentum-dependent mixing term, we show that the $\eta -{\eta }^{\prime }$ system can be described by a meson field renormalization and a new mixing angle $\theta$ which differs from the usual mixing angle ${\theta }_P$ by a small momentum-dependent mixing $d$ term. This new mixing scheme with exact treatment of the momentum-dependent mixing term is actually simpler than the perturbation treatment and should be used in any determination of the $\eta -{\eta }^{\prime }$ mixing angle and the momentum-dependent mixing term. Assuming nonet symmetry for the ${\eta }_0$ singlet amplitude, from the sum rules relating $\theta$ and $d$ to the measured vector meson radiative decay amplitudes, we obtain consistent solutions: $\theta =-(13.99\pm 3.1)°$, $d=0.12\pm 0.03$ from $\rho \to \eta \gamma$ and ${\eta }^{\prime }\to \rho \gamma$ decays, for $\omega$, $\theta =-(15.47\pm 3.1)°$, $d=0.11\pm 0.03$, and for $\varphi$, $\theta =-(12.66\pm 2.1)°$, $d=0.10\pm 0.03$. It seems that vector meson radiative decays would favor a small $\eta -{\eta }^{\prime }$ mixing angle and a small momentum-dependent mixing term.

The HERMES Collaboration recently reported a reevaluation of the strange-quark parton distribution, $S(x)$, based on kaon production in semi-inclusive deep-inelastic scattering. Two distinct results on $S(x)$ at the $x>0.1$ region, one with a sizable magnitude and another with a vanishing content, were reported. We show that the latter result is due to a particular assumption adopted in the analysis. The impact of the new HERMES $S(x)$ result on the extraction of intrinsic light-quark sea in the proton is discussed. Given the large uncertainty in the kaon fragmentation function, we find that the latest HERMES data do not exclude the existence of a significant intrinsic strange-quark sea in the proton. The $x$ dependence of the $(s+\overline{s})/(\overline{u}+\overline{d})$ ratio is also in qualitative agreement with the presence of intrinsic strange-quark sea.

Effective field theory (EFT) formulations of dark matter interactions are a convenient and popular way to quantify LHC bounds on dark matter. However, some EFT operators considered do not respect the weak gauge symmetries of the Standard Model. These operators break down at the electroweak scale, rather than the energy scale of new physics, and are invalid at LHC energies. We carefully discuss the circumstances in which such operators can arise and use the mono-$W$ process to illustrate potential issues in their interpretation and application. We also discuss a simple UV complete model that avoids such difficulties.

In this work we present a common framework for neutrino masses and dark matter. Specifically, we work with a local $\mathcal{B}-\mathcal{L}$ extension of the standard model which has three right-handed neutrinos, $n_{R_i}$, and some extra scalars, $\mathrm{\Phi },{\varphi }_i$, besides the standard model fields. The $n_{R_i}$’s have nonstandard $\mathcal{B}-\mathcal{L}$ quantum numbers and thus these couple to different scalars. This model has the attractive property that an almost automatic ${\mathbb{Z}}_2$ symmetry acting only on a fermionic field, $n_{R3}$, is present. Taking advantage of this ${\mathbb{Z}}_2$ symmetry, we study both the neutrino mass generation via a natural seesaw mechanism at low energy and the possibility of $n_{R3}$ being a dark matter candidate. For this last purpose, we study its relic abundance and its compatibility with the current direct detection experiments.

Deuteron disintegration by charged-current neutrino ($\mathrm{CC}\nu$) scattering offers the possibility to determine the energy of the incident neutrino by measuring in coincidence two of the three resulting particles: a charged lepton (usually a muon) and two protons, where we show that this channel can be isolated from all others—for instance, from those with a pion in the final state. We discuss the kinematics of the process for several detection scenarios, both in terms of kinematic variables that are natural from a theoretical point of view and others that are better matched to experimental situations. The deuteron structure is obtained from a relativistic model (involving an approximation to the Bethe-Salpeter equation) as an extension of a previous, well-tested model used in deuteron electrodisintegration. We provide inclusive and coincidence (semi-inclusive) cross sections for a variety of kinematic conditions, using the plane-wave impulse approximation, introducing final-state hadronic exchange terms (plane-wave Born approximation) and final-state hadronic interactions (distorted-wave Born approximation).

We report the results of a weakly interacting massive particle (WIMP) dark matter search using the full 80.1 live-day exposure of the first stage of the PandaX experiment (PandaX-I) located in the China Jin-Ping Underground Laboratory. The PandaX-I detector has been optimized for detecting low-mass WIMPs, achieving a photon detection efficiency of 9.6%. With a fiducial liquid xenon target mass of 54.0 kg, no significant excess events were found above the expected background. A profile likelihood ratio analysis confirms our earlier finding that the PandaX-I data disfavor all positive low-mass WIMP signals reported in the literature under standard assumptions. A stringent bound on a low-mass WIMP is set at a WIMP mass below $10\mathrm{GeV}/{\mathrm{c}}^2$, demonstrating that liquid xenon detectors can be competitive for low-mass WIMP searches.

Using the bound state version of the topological soliton model for the baryons we show that the existence of a bound (or quasibound) $\overline{D}$-soliton state leads to the possibility of having hidden charm pentaquarks with quantum numbers and masses, which are compatible with those of the candidates recently reported by the LHCb experiment. The implications of heavy quark symmetry are elaborated.

We show that in $1+1$ dimensional conformal field theories, exciting a state with a local operator increases the Rényi entanglement entropies by a constant which is the same for every member of the conformal family. Hence, it is an intrinsic parameter that characterizes local operators from the perspective of quantum entanglement. In rational conformal field theories this constant corresponds to the logarithm of the quantum dimension of the primary operator. We provide several detailed examples for the second Rényi entropies and a general derivation.

We study the equation of motion for the Noether current in an electron gas within the framework of the Schwinger-Keldysh closed-time-path formalism. The equation is shown to be highly nonlinear and irreversible even for a noninteracting, ideal gas of electrons at nonzero density. We truncate the linearized equation of motion, written as the Laurent series in Fourier space, so that the resulting expressions are local in time, both at zero and at small finite temperatures. Furthermore, we show that the one-loop Coulomb interactions only alter the physical picture quantitatively, while preserving the characteristics of the dynamics that the electric current exhibits in the absence of interactions. As a result of the composite nature of the Noether current, composite sound waves are found to be the dominant IR collective excitations at length scales between the inverse Fermi momentum and the mean free path that would exist in an interacting electron gas. We also discuss the difference and the transition between the hydrodynamical regime of an ideal gas, defined in this work, and the hydrodynamical regime in phenomenological hydrodynamics, which is normally used for the description of interacting gases.

In this work nonperturbative aspects of quantum gravity are investigated using the lattice formulation, and some new results are presented for critical exponents, amplitudes, and invariant correlation functions. Values for the universal scaling dimensions are compared with other nonperturbative approaches to gravity in four dimensions, and specifically to the conjectured value for the universal critical exponent $\nu =1/3$. The lattice results are generally consistent with gravitational antiscreening, which would imply a slow increase in the strength of the gravitational coupling with distance, and presented herein are detailed estimates for exponents and amplitudes characterizing this slow rise. Furthermore, it is shown that in the lattice approach (as for gauge theories) the quantum theory is highly constrained, and eventually, by virtue of scaling, depends on a rather small set of physical parameters. Arguments are given in support of the statement that the fundamental reference scale for the growth of the gravitational coupling $G$ with distance is represented by the observed scaled cosmological constant $\lambda$, which in gravity acts as an effective nonperturbative infrared cutoff. In this nonperturbative vacuum condensate picture a fundamental relationship emerges among the scale characterizing the running of $G$ at large distances, the macroscopic scale for the curvature as described by the observed cosmological constant, and the behavior of invariant gravitational correlation functions at large distances. Overall, the lattice results suggest that the slow infrared growth of $G$ with distance should become observable only on very large distance scales, comparable to $\lambda$. One may hope that future high precision satellite experiments could possibly come within reach of this small quantum correction, as suggested by the vacuum condensate picture of quantum gravity.

The dynamics of precessing binary black holes (BBHs) in the post-Newtonian regime has a strong timescale hierarchy: the orbital timescale is very short compared to the spin-precession timescale which, in turn, is much shorter than the radiation-reaction timescale on which the orbit is shrinking due to gravitational-wave emission. We exploit this timescale hierarchy to develop a multiscale analysis of BBH dynamics elaborating on the analysis of Kesden et al. [Phys. Rev. Lett. 114, 081103 (2015)]. We solve the spin-precession equations analytically on the precession time and then implement a quasiadiabatic approach to evolve these solutions on the longer radiation-reaction time. This procedure leads to an innovative “precession-averaged” post-Newtonian approach to studying precessing BBHs. We use our new solutions to classify BBH spin precession into three distinct morphologies, then investigate phase transitions between these morphologies as BBHs inspiral. These precession-averaged post-Newtonian inspirals can be efficiently calculated from arbitrarily large separations, thus making progress towards bridging the gap between astrophysics and numerical relativity.