We present a lattice quantum chromodynamics determination of the scalar and vector form factors for the $B_s\to D_s\ell \nu$ decay over the full physical range of momentum transfer. In conjunction with future experimental data, our results will provide a new method to extract $|V_{cb}|$, which may elucidate the current tension between exclusive and inclusive determinations of this parameter. Combining the form factor results at nonzero recoil with recent HPQCD results for the $B\to D\ell \nu$ form factors, we determine the ratios $f_0^{B_s\to D_s}(M_{\pi }^2)/f_0^{B\to D}(M_K^2)=1.000(62)$ and $f_0^{B_s\to D_s}(M_{\pi }^2)/f_0^{B\to D}(M_{\pi }^2)=1.006(62)$. These results give the fragmentation fraction ratios $f_s/f_d=0.310(30{)}_{\text{stat}}(21{)}_{\text{syst}}(6{)}_{\text{theor}}(38{)}_{\text{latt}}$ and $f_s/f_d=0.307(16{)}_{\text{stat}}(21{)}_{\text{syst}}(23{)}_{\text{theor}}(44{)}_{\text{latt}}$, respectively. The fragmentation fraction ratio is an important ingredient in experimental determinations of $B_s$ meson branching fractions at hadron colliders, in particular for the rare decay $\mathcal{B}(B_s\to {\mu }^{+}{\mu }^{-})$. In addition to the form factor results, we make the first prediction of the branching fraction ratio $R(D_s)=\mathcal{B}(B_s\to D_s\tau \nu )/\mathcal{B}(B_s\to D_s\ell \nu )=0.301(6)$, where $\ell$ is an electron or muon. Current experimental measurements of the corresponding ratio for the semileptonic decays of $B$ mesons disagree with Standard Model expectations at the level of nearly four standard deviations. Future experimental measurements of $R(D_s)$ may help understand this discrepancy.

It has been known for a long time that hyperons produced in hadronic collisions are polarized perpendicular to the production plane of the reaction. This effect cannot be described by using twist-2 collinear parton correlators only. Here we compute the contribution of twist-3 fragmentation functions to the production of transversely polarized hyperons in unpolarized proton-proton collisions in the framework of collinear factorization. By taking into account the relations among the relevant twist-3 fragmentation functions which follow from the QCD equation of motion and the Lorentz invariance property of the correlators, we present the leading-order cross section for this term.

We perform a full amplitude analysis of the process $e^{+}{e}^{-}\to J/\psi D\overline{D}$, where $D$ refers to either $D^0$ or $D^{+}$. A new charmoniumlike state $X^{*}(3860)$ that decays to $D\overline{D}$ is observed with a significance of $6.5\sigma$. Its mass is $({3862}_{-32}^{+26}{}_{-13}^{+40})\mathrm{MeV}/c^2$, and its width is $({201}_{-67}^{+154}{}_{-82}^{+88})\mathrm{MeV}$. The $J^{PC}=0^{++}$ hypothesis is favored over the $2^{++}$ hypothesis at the level of $2.5\sigma$. The analysis is based on the $980{\mathrm{fb}}^{-1}$ data sample collected by the Belle detector at the asymmetric-energy $e^{+}{e}^{-}$ collider KEKB.

We propose a scenario to generate flavor violating $Z^{\prime }$ interactions at one-loop level by introducing $U(1{)}_{\mu -\tau }$ gauge symmetry, extra vectorlike quark doublets $Q_a^{\prime }$, and a singlet scalar $\chi$. Both $Q_a^{\prime }$ and $\chi$ are charged under $U(1{)}_{\mu -\tau }$ and carry odd dark $Z_2$ parity. Assuming that $\chi$ is the dark matter (DM) of the Universe and imposing various constraints from a dark matter search, flavor physics, and a collider search for $Q_a^{\prime }$, one can show that radiative corrections to $b\to s{Z}^{\prime *}\to s{l}^{+}{l}^{-}$ involving $Q_a^{\prime }$ and $\chi$ can induce $\mathrm{\Delta }{C}_9\sim -1$, which can resolve the LHCb anomalies related with $B\to K^{(*)}{\ell }^{+}{\ell }^{-}$. Therefore, both DM and $B$ physics anomalies can be accommodated in the model.

We study the behavior of linear perturbations in multifield coupled quintessence models. Using gauge-invariant linear cosmological perturbation theory we provide the full set of governing equations for this class of models, and solve the system numerically. We apply the numerical code to generate growth functions for various examples, and compare these both to the standard $\mathrm{\Lambda }$ cold dark matter model and to current and future observational bounds. Finally, we examine the applicability of the “small scale approximation” often used to calculate growth functions in quintessence models, in light of upcoming experiments such as SKA and Euclid. We find the deviation of the full equation results for large $k$ modes from the approximation exceeds the experimental uncertainty for these future surveys. The numerical code, Pyessence, written in Python will be publicly available.

The gauge kinetic mixing in general is allowed in models with multiple Abelian gauge groups. In this paper, we investigate the gauge kinetic mixing in the framework of U(1) extensions of the minimal supersymmetric extension of the standard model (SM). It enlarges the viable parameter space, and has an important effect on the particle mass spectrum as well as the $Z_2$ coupling with matters. The SM-like Higgs boson mass can be enhanced with a nonzero kinetic mixing parameter and the muon $g-2$ tension is slightly less severe than in the case of no mixing. We present the results from both benchmark analysis and global parameter scan. Various theoretical and phenomenological constraints have been considered. The recent LHC searches for the $Z_2$-boson are important for the case of large positive kinetic mixing where the $Z_2$ coupling is enhanced, and severely constrain scenarios with $M_{Z_2}<2.8\mathrm{TeV}$. The viable dark matter candidate predicted by the model is either the neutralino or the right-handed sneutrino. Cosmological constraints from dark matter searches play a significant role in excluding the parameter space. Portions of the parameter space with relatively low sparticle mass spectrum can be successfully explored in the LHC run-2 as well as future linear colliders and dark matter searches.

We investigate the Polyakov loop effects on the QCD phase diagram by using the strong-coupling ($1/g^2$) expansion of the lattice QCD (SC-LQCD) with one species of unrooted staggered quark, including $\mathcal{O}(1/g^4)$ effects. We take account of the effects of Polyakov loop fluctuations in Weiss mean-field approximation (MFA), and compare the results with those in the Haar-measure MFA (no fluctuation from the mean-field). The Polyakov loops strongly suppress the chiral transition temperature in the second-order/crossover region at small chemical potential ($\mu$), while they give a minor modification of the first-order phase boundary at larger $\mu$. The Polyakov loops also account for a drastic increase of the interaction measure near the chiral phase transition. The chiral and Polyakov loop susceptibilities $({\chi }_{\sigma },{\chi }_{\ell })$ have their peaks close to each other in the second-order/crossover region. In particular in Weiss MFA, there is no indication of the separated deconfinement transition boundary from the chiral phase boundary at any $\mu$. We discuss the interplay between the chiral and deconfinement dynamics via the bare quark mass dependence of susceptibilities ${\chi }_{\sigma ,\ell }$.

We present a lattice computation of the isospin-breaking corrections to pseudoscalar meson masses using the gauge configurations produced by the European Twisted Mass Collaboration with $N_f=2+1+1$ dynamical quarks at three values of the lattice spacing ($a\simeq 0.062$, 0.082, and 0.089 fm) with pion masses in the range $M_{\pi }\simeq 210–450\mathrm{MeV}$. The strange and charm quark masses are tuned at their physical values. We adopt the RM123 method based on the combined expansion of the path integral in powers of the $d$- and $u$-quark mass difference (${\widehat{m}}_d-{\widehat{m}}_u$) and of the electromagnetic coupling ${\alpha }_{em}$. Within the quenched QED approximation, which neglects the effects of the sea-quark charges, and after the extrapolations to the physical pion mass and to the continuum and infinite volume limits, we provide results for the pion, kaon, and (for the first time) charmed-meson mass splittings, for the prescription-dependent parameters ${\epsilon }_{{\pi }^0}$, ${\epsilon }_{\gamma }(\overline{MS},2\mathrm{GeV})$, ${\epsilon }_{K^0}(\overline{MS},2\mathrm{GeV})$, related to the violations of the Dashen’s theorem, and for the light quark mass difference $({\widehat{m}}_d-{\widehat{m}}_u)(\overline{MS},2\mathrm{GeV})$.

We present a search for a light sterile neutrino using three years of atmospheric neutrino data from the DeepCore detector in the energy range of approximately 10–60 GeV. DeepCore is the low-energy subarray of the IceCube Neutrino Observatory. The standard three-neutrino paradigm can be probed by adding an additional light ($\mathrm{\Delta }{m}_{41}^2\sim 1{\mathrm{eV}}^2$) sterile neutrino. Sterile neutrinos do not interact through the standard weak interaction and, therefore, cannot be directly detected. However, their mixing with the three active neutrino states leaves an imprint on the standard atmospheric neutrino oscillations for energies below 100 GeV. A search for such mixing via muon neutrino disappearance is presented here. The data are found to be consistent with the standard three-neutrino hypothesis. Therefore, we derive limits on the mixing matrix elements at the level of $|U_{\mu 4}{|}^2<0.11$ and $|U_{\tau 4}{|}^2<0.15$ (90% C.L.) for the sterile neutrino mass splitting $\mathrm{\Delta }{m}_{41}^2=1.0{\mathrm{eV}}^2$.

In this article, we apply background-independent renormalization group methods to spin foam quantum gravity. It is aimed at extending and elucidating the analysis of a companion paper, in which the existence of a fixed point in the truncated renormalization group flow for the model was reported. Here, we repeat the analysis with various modifications and find that both qualitative and quantitative features of the fixed point are robust in this setting. We also go into details about the various approximation schemes employed in the analysis.

We discuss the effects of the electromagnetic interaction in high-energy proton collisions with nuclei of large Z at strong coupling $\lambda =g^2{N}_c$. Using the holographic dual limit of large $N_c>\lambda \gg 1$, we describe the Reggeon exchange as a twisted surface and show that it gets essentially modified by the electromagnetic interaction.

Light bosonic fields are ubiquitous in extensions of the Standard Model. Even when minimally coupled to gravity, these fields might evade the assumptions of the black-hole no-hair theorems and give rise to spinning black holes which can be drastically different from the Kerr metric. Furthermore, they allow for self-gravitating compact solitons, known as (scalar or Proca) boson stars. The quasiperiodic oscillations (QPOs) observed in the x-ray flux emitted by accreting compact objects carry information about the strong-field region, thus providing a powerful tool to constrain deviations from Kerr’s geometry and to search for exotic compact objects. By using the relativistic precession model as a proxy to interpret the QPOs in terms of geodesic frequencies, we investigate how the QPO frequencies could be used to test the no-hair theorem and the existence of light bosonic fields near accreting compact objects. We show that a detection of two QPO triplets with current sensitivity can already constrain these models and that the future eXTP mission or a LOFT-like mission can set very stringent constraints on black holes with bosonic hair and on (scalar or Proca) boson stars. The peculiar geodesic structure of compact scalar/Proca boson stars implies that these objects can easily be ruled out as alternative models for x-ray source GRO J1655-40.

By choosing an appropriate vielbein basis, we obtain a class of spherically-symmetric solutions in $f(T)$ gravities. The solutions are asymptotic to Minkowski spacetimes with leading falloffs the same as those of the Schwarzschild black hole. In general, these solutions have branch-cut singularities in the middle. For appropriately chosen $f(T)$ functions, extremal black holes can also emerge. Furthermore, we obtain wormhole configurations whose spatial section is analogous to an Ellis wormhole, but $-g_{tt}$ runs from 0 to 1 as the proper radial coordinate runs from $-\infty$ to $+\infty$. Thus a signal sent from $-\infty$ to $+\infty$ through the wormhole will be infinitely red-shifted. We call such a spacetime configuration a dark wormhole. By introducing a bare cosmological constant ${\mathrm{\Lambda }}_0$, we construct smooth solitons that are asymptotic to local AdS with an effective ${\mathrm{\Lambda }}_{\text{eff}}$. In the middle of bulk, the soliton metric behaves like the AdS of bare ${\mathrm{\Lambda }}_0$ in global coordinates. We also embed AdS planar and Lifshitz black holes in $f(T)$ gravities. Finally we couple the Maxwell field to the $f(T)$ theories and construct electrically-charged solutions.

A generalization of Bekenstein’s Tensor-Vector-Scalar (TeVeS) model of modified gravity has recently been proposed as an alternative to dark matter. This model—which we will refer to as g-TeVeS—utilizes a Galileon-induced Vainshtein mechanism to suppress modifications to General Relativity in strong gravity regimes and so avoids the need to introduce the baroque kinetic terms that typically exist in relativistic models of modified Newtonian dynamics (MOND). We explore the behavior of this model in spacetimes with exact Friedmann-Robertson-Walker (FRW) symmetry. The ability of the theory to recover MOND phenomenology places restrictions on the theory’s parameter space and it is found that within an estimate of this area of parameter space the theory cannot successfully approximate the Friedmannian cosmological behavior of cold dark matter. It is found that much closer agreement may be recovered in other regions of the theory’s parameter space and the reasons for this are discussed.

The precession angular velocity of a gyroscope moving along a general geodesic in the Kerr spacetime is analyzed using the geometric properties of the spacetime. Natural frames along the gyroscope world line are explicitly constructed by boosting frames adapted to fundamental observers. A novel geometrical description is given to Marck’s construction of a parallel propagated orthonormal frame along a general geodesic, identifying and clarifying the special role played by the Carter family of observers in this general context, thus extending previous discussion for the equatorial plane case.

We present a class of spherically symmetric spacetimes corresponding to bubbles separating two regions with constant values of the scalar curvature, or equivalently with two different cosmological constants, in quadratic $F(R)$ theory. The bubbles are obtained by means of the junction formalism, and the matching hypersurface supports in general a thin shell and a gravitational double layer. In particular, we find that pure double layers are possible for appropriate values of the parameters of the model whenever the quadratic coefficient is negative. This is the first example of a pure double layer in a gravitational theory.

Motivated by $\alpha$-attractor models, in this paper we consider a Gauss-Bonnet inflation with an E-model-type of potential. We consider the Gauss-Bonnet coupling function to be the same as the E-model potential. In the small $\alpha$ limit, we obtain an attractor at $r=0$ as expected, and in the large $\alpha$ limit, we recover the Gauss-Bonnet model with potential and coupling function of the form ${\varphi }^{2n}$. We study perturbations and non-Gaussianity in this setup, and we find some constraints on the model’s parameters in comparison with PLANCK data sets. We study also the reheating epoch after inflation in this setup. For this purpose, we seek the number of e-folds and temperature during reheating epoch. These quantities depend on the model’s parameter and the effective equation of state of the dominating energy density in the reheating era. We find some observational constraints on these parameters.

The antiproton-to-proton ratio in the cosmic-ray spectrum is a sensitive probe of new physics. Using recent measurements of the cosmic-ray antiproton and proton fluxes in the energy range of 1–1000 GeV, we study the contribution to the $\overline{p}/p$ ratio from secondary antiprotons that are produced and subsequently accelerated within individual supernova remnants. We consider several well-motivated models for cosmic-ray propagation in the interstellar medium and marginalize our results over the uncertainties related to the antiproton production cross section and the time-, charge-, and energy-dependent effects of solar modulation. We find that the increase in the $\overline{p}/p$ ratio observed at rigidities above $\sim 100\mathrm{GV}$ cannot be accounted for within the context of conventional cosmic-ray propagation models, but is consistent with scenarios in which cosmic-ray antiprotons are produced and subsequently accelerated by shocks within a given supernova remnant. In light of this, the acceleration of secondary cosmic rays in supernova remnants is predicted to substantially contribute to the cosmic-ray positron spectrum, accounting for a significant fraction of the observed positron excess.

The dark matter time projection chamber (DMTPC) is a direction-sensitive detector designed to measure the direction of recoiling ${}^{19}\mathrm{F}$ and ${}^{12}\mathrm{C}$ nuclei in low-pressure ${\mathrm{CF}}_4$ gas using optical and charge readout systems. In this paper, we employ measurements from two DMTPC detectors, with operating pressures of 30–60 torr, to develop and validate a model of the directional response and performance of such detectors as a function of recoil energy. Using our model as a benchmark, we formulate the necessary specifications for a scalable directional detector with sensitivity comparable to that of current-generation counting (nondirectional) experiments, which measure only recoil energy. Assuming the performance of existing DMTPC detectors, as well as current limits on the spin-dependent WIMP-nucleus cross section, we find that a 10–20 kg scale direction-sensitive detector is capable of correlating the measured direction of nuclear recoils with the predicted direction of incident dark matter particles and providing decisive ($3\sigma$) confirmation that a candidate signal from a nondirectional experiment was indeed induced by elastic scattering of dark matter particles off of target nuclei.