Charged-particle multiplicity and summed values of the transverse momentum ($p_{\mathrm{T}}$) have been utilized for estimating forward-backward (FB) correlation strength for EPOS3 simulated proton-proton ($pp$) events with and without hydrodynamical evolution of particles at center-of-mass energies $\sqrt{s}=0.9$, 2.76, and 7 TeV for different pseudorapidity window width ($\delta \eta$) and gap between the FB windows (${\eta }_{gap}$). We have studied the variation of FB correlation strength with ${\eta }_{gap}$, $\delta \eta$, $\sqrt{s}$, different $p_{\mathrm{T}}$ cuts, and multiplicity classes. Results are compared with the corresponding ALICE and ATLAS data. EPOS3 model qualitatively reproduces the overall variation of correlation strength of the LHC data. However, quantitative agreement is better for $pp$ events, generated using EPOS3 with hydrodynamical evolution of particles, with ATLAS data.

The process $e^{+}{e}^{-}\to \varphi {\eta }^{\prime }$ has been studied for the first time in detail using data sample collected with the BESIII detector at the BEPCII collider at center of mass energies from 2.05 to 3.08 GeV. A resonance with quantum numbers $J^{PC}=1^{--}$ is observed with mass $M=(2177.5\pm 4.8(\mathrm{stat})\pm 19.5(\mathrm{syst}))\mathrm{MeV}/c^2$ and width $\mathrm{\Gamma }=(149.0\pm 15.6(\mathrm{stat})\pm 8.9(\mathrm{syst}))\mathrm{MeV}$ with a statistical significance larger than $10\sigma$, including systematic uncertainties. If the observed structure is identified with the $\varphi (2170)$, then the ratio of partial width between the $\varphi {\eta }^{\prime }$ by BESIII and $\varphi \eta$ by BABAR is (${\mathcal{B}}_{\varphi \eta }^R{\mathrm{\Gamma }}_{ee}^R)/({\mathcal{B}}_{\varphi {\eta }^{\prime }}^R{\mathrm{\Gamma }}_{ee}^R)=0.23\pm 0.10(\mathrm{stat})\pm 0.18(\mathrm{syst})$, which is smaller than the prediction of the $s\overline{s}g$ hybrid models by several orders of magnitude.

This paper reports the first differential measurement of the charged-current ${\overline{\nu }}_{\mu }$ interaction cross section on water with no pions in the final state. The unfolded flux-averaged measurement using the T2K off-axis near detector is given in double-differential bins of ${\mu }^{+}$ momentum and angle. The integrated cross section in a restricted phase space is $\sigma =(1.11\pm 0.18)\times {10}^{-38}{\mathrm{cm}}^2$ per water molecule. Comparisons with several nuclear models are also presented.

We comment on the paper of S. Postnikov et al. [Phys. Rev. D 82, 024016 (2010)] and give a modified formula that needs to be taken into account when calculating the tidal Love number of neutron stars in case a first order phase-transition occurs at nonzero pressure. We show that the error made when using the original formula tends to zero as $p\to 0$, and we estimate the maximum relative error to be $\sim 5\%$ if the density discontinuity is at larger densities.

Previous works on black hole shadows have been primarily focused on studying shadows in asymptotically flat and anti–de Sitter space times. In the present work, we find general expressions for asymptotically de Sitter black hole shadow as seen by static and comoving observers, for any spherically symmetric black hole solution, in any space time dimension in generic theories of gravity. As test cases, we use the derived general expressions to study the shadow of three different black hole solutions: the four dimensional Reissner-Nordström de Sitter black hole, the recently proposed four dimensional Gauss Bonnet de Sitter black hole and the five dimensional Gauss Bonnet de Sitter black hole.

Primordial black holes that survive until the present have been considered as a dark matter candidate. In this paper we argue that primordial 2-2-hole remnants provide a more promising and testable alternative. 2-2-holes arise in quadratic gravity as a new family of classical solutions for ultracompact matter distributions and they possess the black hole exterior without an event horizon. They may serve as the endpoint of gravitational collapse, providing a resolution for the information loss problem. Intriguing thermodynamic behavior is found for these objects when sourced by a thermal gas. A large 2-2-hole radiates with a Hawking-like temperature and exhibits an entropy-area law. At a late stage, the evaporation slows down and essentially stops as the mass asymptotically approaches a minimal value. This remnant mass is determined by a fundamental scale in quadratic gravity. We study the cosmological and astrophysical implications of having these remnants as dark matter and derive the corresponding constraints. A distinctive phenomenon associated with remnant mergers occurs, predicting fluxes of high-energy astrophysical particles due to the spectacular evaporation of the merger product. Measurements of high-energy photon and neutrino fluxes could possibly bound the remnant mass to be not far above the Planck mass. Early universe physics, on the other hand, requires that 2-2-holes quickly evolve into the remnant state after formation, putting an upper bound on the formation mass.

A complete theory of gravity impels us to go beyond Einstein’s general relativity. One promising approach lies in a new class of teleparallel theory of gravity named $f(Q)$, where the nonmetricity $Q$ is responsible for the gravitational interaction. The important roles any of these alternative theories should obey are the energy condition constraints. Such constraints establish the compatibility of a given theory with the causal and geodesic structure of space-time. In this work, we present a complete test of energy conditions for $f(Q)$ gravity models. The energy conditions allowed us to fix our free parameters, restricting the families of $f(Q)$ models compatible with the accelerated expansion our Universe passes through. Our results strengthen the viability of $f(Q)$ theory, leading us close to the dawn of a complete theory for gravitation.

The dressed-metric approach is shown to violate general covariance by demonstrating that it cannot have an off-shell completion in which the correct infinitesimal relations of space-time hypersurface deformations are realized. The main underlying reason—a separation of background degrees of freedom and modes of inhomogeneity that is incompatible with covariance—is shared with other approaches such as hybrid loop quantum cosmology.

We consider gravitational wave (GW) sources with an associated electromagnetic (EM) counterpart and analyze the time delay between both signals in the presence of lensing. If GWs have wavelengths comparable to the Schwarzschild radius of astrophysical lenses, they must be treated with wave optics, whereas EM waves are typically well within the approximation of geometric optics. With concrete examples, we confirm that the GW signal never arrives before its EM counterpart, if both are emitted at the same time. However, during the inspiral of a binary, peaks of the GW waveform can arrive before their EM counterpart. We stress that this is only an apparent superluminality, since the GW waveform is both distorted and further delayed with respect to light. In any case, measuring the multimessenger time delay and correctly interpreting it has important implications for unveiling the distribution of lenses, testing the nature of gravity, and probing the cosmological expansion history.

Gravitational waves from the merger of two neutron stars cannot be easily distinguished from those produced by a comparable-mass mixed binary in which one of the companions is a black hole. Low-mass black holes are interesting because they could form in the aftermath of the coalescence of two neutron stars, from the collapse of massive stars, from matter overdensities in the primordial Universe, or as the outcome of the interaction between neutron stars and dark matter. Gravitational waves carry the imprint of the internal composition of neutron stars via the so-called tidal deformability parameter, which depends on the neutron star equation of state and is equal to zero for black holes. We present a new data analysis strategy powered by Bayesian inference and machine learning to identify mixed binaries, hence low-mass black holes, using the distribution of the tidal deformability parameter inferred from gravitational-wave observations.

We studied the three-dimensional Thirring model in the limit of an infinite number of flavors at finite temperature and density. We calculated the number density as a function of temperature and the density at zero temperature serves as a relevant parameter. A three-dimensional free fermion gas behavior as the density at zero temperature approaches zero smoothly crosses over to a two-dimensional free fermion gas behavior as the density at zero temperature approaches infinity.

Within the framework of covariant confined quark model, we compute the transition form factors of $D$ and $D_s$ mesons decaying to light scalar mesons $f_0(980)$ and $a_0(980)$. The transition form factors are then utilized to compute the semileptonic branching fractions. We study the channels, namely, $D_{(s)}^{+}\to f_0(980){\ell }^{+}{\nu }_{\ell }$ and $D\to a_0(980){\ell }^{+}{\nu }_{\ell }$ for $\ell =e$ and $\mu$. For computation of semileptonic branching fractions, we consider the $a_0(980)$ meson to be the conventional quark-antiquark structure and the $f_0(980)$ meson as the admixture of $s\overline{s}$ and light quark-antiquark pairs. Our findings are found to support the recent BESIII data.

Motivated by the long-standing tension in the muon anomalous magnetic moment (AMM) and persistent observations of B-physics anomalies in $R_{D^{(*)}}$ and $R_{K^{(*)}}$ ratios, we construct a simple two-loop radiative neutrino mass model, and propose a combined explanations of all these apparently disjoint phenomena within this framework. Our proposed model consists of two scalar leptoquarks (LQs), a $SU(2{)}_L$ singlet $S_1\sim (\overline{3},1,1/3)$ and a $SU(2{)}_L$ triplet $S_3\sim (\overline{3},3,1/3)$ to accommodate $R_{D^{(*)}}$ and $R_{K^{(*)}}$ anomalies, respectively. The muon receives chirality-enhanced contribution toward its $g-2$ due to the presence of $S_1$ LQ that accounts for the observed deviation from the Standard Model prediction. Furthermore, we introduce a $SU(2{)}_L$ singlet scalar diquark $\omega \sim (\overline{6},1,2/3)$, which is necessary to break lepton number and generate neutrino mass radiatively with the aid of $S_1$ and $S_3$ LQs. We perform a detailed phenomenological analysis of this set-up and demonstrate its viability by providing benchmark points where a fit to the neutrino oscillation data together with proper explanations of the muon AMM puzzle and flavor anomalies are accomplished while simultaneously meeting all other flavor violation and collider bounds.

We extend the nonsupersymmetric SO(10) grand unification theories by adding a horizontal symmetry, which connects the three generations of fermions. Without committing to any specific symmetry group, we investigate the 1-loop renormalization group evolutions of the gauge couplings with one and two intermediate breaking scales. We find that depending on the SO(10) breaking chains, gauge coupling unification is compatible with only a handful of choices of representations of the Higgs bosons under the horizontal symmetry.

We present a novel unifying interpretation of excess event rates observed in several dark matter direct-detection experiments that utilize single-electron threshold semiconductor detectors. Despite their different locations, exposures, readout techniques, detector composition, and operating depths, these experiments all observe statistically significant excess event rates of $\sim 10\mathrm{Hz}/\mathrm{kg}$. However, none of these persistent excesses has yet been reported as a dark matter signal because individually, each can be attributed to different well-motivated but unmodeled backgrounds, and taken together, they cannot be explained by dark matter particles scattering elastically off detector nuclei or electrons. We show that these results can be reconciled if the semiconductor detectors are seeing a collective inelastic process, consistent with exciting a plasmon. We further show that plasmon excitation could arise in two compelling dark matter scenarios, both of which can explain rates of existing signal excesses in germanium and, at least at the order of magnitude level, across several single-electron threshold detectors. At least one of these scenarios also yields the correct relic density from thermal freeze-out. Both dark matter scenarios motivate a radical rethinking of the standard interpretations of dark matter-electron scattering from recent experiments.

We study thermodynamic properties of $N_f=2+1$ QCD on the lattice adopting a nonperturbatively $O(a)$-improved Wilson quark action and the renormalization group-improved Iwasaki gauge action. To cope with the problems due to explicit violation of the Poincaré and chiral symmetries, we apply the small flow-time expansion ($\mathbf{S}\mathbf{F}\mathit{t}\mathbf{X}$) method based on the gradient flow, which is a general method to correctly calculate any renormalized observables on the lattice. In this method, the matching coefficients in front of operators in the small flow-time expansion are calculated by perturbation theory thanks to the asymptotic freedom around the small flow-time limit. In a previous study using one-loop matching coefficients, we found that the $\mathrm{SF}t\mathrm{X}$ method works well for the equation of state extracted from diagonal components of the energy-momentum tensor and for the chiral condensates and susceptibilities. In this paper, we study the effect of two-loop matching coefficients which have been calculated by Harlander et al. recently. We also test the influence of the renormalization scale in the $\mathrm{SF}t\mathrm{X}$ method. We find that, by adopting the ${\mu }_0$ renormalization scale of Harlander et al. instead of the conventional ${\mu }_d=1/\sqrt{8t}$ scale, the linear behavior at large flow-times is improved so that we can perform the $t\to 0$ extrapolation of the $\mathrm{SF}t\mathrm{X}$ method more confidently. In the calculation of the two-loop matching coefficients by Harlander et al., the equation of motion for quark fields was used. For the entropy density in which the equation of motion has no effects, we find that the results using the two-loop coefficients agree well with those using one-loop coefficients. On the other hand, for the trace anomaly which is affected by the equation of motion, we find discrepancies between the one- and two-loop results at high temperatures. By comparing the results of one-loop coefficients with and without using the equation of motion, the main origin of the discrepancies is suggested to be attributed to contamination of $O((aT{)}^2)=O(1/N_t^2)$ discretization errors in the equation of motion at $N_t\lesssim 10$.

We study the implications of recent lattice QCD results for the magnetic field dependence of the quarks dynamical masses on the ’t Hooft determinant extended Nambu–Jona-Lasinio model in the light and strange quark sectors (up, down and strange). The parameter space is constrained at vanishing magnetic field, using the quarks dynamical masses and the meson spectra, whereas at nonvanishing magnetic field strength the dependence of the dynamical masses of two of the quark flavors is used to fit a magnetic field dependence on the model couplings, both the four-fermion Nambu–Jona-Lasinio interaction and the six-fermion ’t Hooft flavor determinant. We found that this procedure reproduces the inverse magnetic catalysis, and the strength of the scalar coupling decreases with the magnetic field, while the strength of the six-fermion ’t Hooft flavor determinant increases with the magnetic field.