In this work, we make a detailed analysis on the penguin-dominant processes $B_{(s)}^0\to \varphi \varphi \to (K^{+}{K}^{-})(K^{+}{K}^{-})$ in the perturbative QCD (PQCD) approach. In addition to the dominant $P$-wave resonance, the scalar background $f_0(980)\to K^{+}{K}^{-}$ is also accounted for. We improve the Gegenbauer moments in $KK$ two-meson distribution amplitudes by fitting the PQCD factorization formulas to measured branching ratios of three-body and four-body $B$ decays. We extract the branching ratios of two-body $B_{(s)}^0\to \varphi \varphi$ decays from the corresponding four-body-decay modes and calculate the relevant polarization fractions together with two relative phases ${\varphi }_{\parallel ,\perp }$, which are consistent with the previous theoretical predictions. The PQCD predictions for the “true” triple product asymmetries (TPAs) are zero, which are expected in the standard model due to the vanishing weak phase difference, and support the current data reported by the CDF and LHCb Collaborations. A large “fake” TPA ${\mathcal{A}}_{\mathrm{T}\text{−}\mathrm{fake}}^1=30.4\%$ of the decay $B_s^0\to \varphi \varphi \to (K^{+}{K}^{-})(K^{+}{K}^{-})$ is predicted for the first time, which indicates the presence of the significant final-state interactions. The TPAs of the rare decay channel $B^0\to \varphi \varphi \to (K^{+}{K}^{-})(K^{+}{K}^{-})$ are also predicted and can be tested in the near future.

A set of comparisons among neutrino interaction experiments [MiniBooNE, MINERvA, Tokai-to-Kamioka (T2K), and MicroBooNE] is presented. This gives a broad view of the field of neutrino-nucleus interactions. The emphasis is on charged-current inclusive, quasielastic-like, and pion production experiments. Measurements are compared in new ways. Comparisons of recent data with available event generator codes are made more comprehensively than is regularly found in most previous publications. Generator studies show sensitivities for experimental model dependence. Efficiencies calculated with different generators are presented in a novel way. A comparison of different forward-folding techniques is also presented.

Motivated by the search for the QCD critical point, we discuss how to obtain the singular behavior of a thermodynamic system near a critical point, namely the Lee-Yang singularities, from a limited amount of local data generated in a different region of the phase diagram. We show that by using a limited number of Taylor series coefficients, it is possible to reconstruct the equation of state past the radius of convergence, in particular in the critical region. Furthermore we also show that it is possible to extend this reconstruction to go from a crossover region to the first-order transition region in the phase diagram, using a uniformizing map to pass between Riemann sheets. We illustrate these ideas via the chiral random matrix model and the Ising model.

In most experiments to test the weak equivalence principle, the test objects coupled with gravity are treated as point particles. To study whether the weak equivalence principle is obeyed by nonlocal objects, especially wave packets with interesting physical configurations, one must first properly define the trajectory of such objects. A phenomenon called the geometric spin Hall effect suggests that one can directly use the energy-momentum tensor to describe the motion of wave packets. In this paper, we construct spin-polarized free-falling electromagnetic wave packets in gravity, and calculate the evolution of the center of the energy-momentum tensor. We find that the electromagnetic wave packets with opposite helicity are separated in the direction perpendicular to spin and gravity. This behavior is thus a kind of gravitational birefringence, and it means that motions of these spin-polarized wave packets in gravity do violate the weak equivalence principle. Furthermore, we find that the trajectories defined by different components and expressions of the energy-momentum tensor are not the same, and they are all different from the trajectory given by the Mathisson-Papapetrou-Dixon equations with the constraint $p_{\mu }{S}^{\mu \rho }=0$. This suggests that the trajectory of spin-polarized wave packets in gravity, and its confrontation with the weak equivalence principle, depend not only on the gravitational interaction but also strongly on how the wave packets are measured and analyzed.

We propose a new approach toward reconstructing the late-time near-horizon geometry of merging binary black holes, and toward computing gravitational-wave echoes from exotic compact objects. A binary black-hole merger spacetime can be divided by a timelike hypersurface into a black-hole perturbation (BHP) region (in which the spacetime geometry can be approximated by homogeneous linear perturbations of the final Kerr black hole) and a nonlinear region. At late times, the boundary between the two regions is an infalling shell. The BHP region contains late-time gravitational waves emitted toward the future horizon, as well as those emitted toward future null infinity. In this region, by imposing no-ingoing-wave conditions at past null infinity and matching outgoing waves at future null infinity with waveforms computed from numerical relativity, we can obtain waves that travel toward the future horizon. In particular, the Newman-Penrose ${\psi }_0$ associated with the ingoing wave on the horizon is related to tidal deformations measured by fiducial observers floating above the horizon. We further determine the boundary of the BHP region on the future horizon by imposing that ${\psi }_0$ inside the BHP region can be faithfully represented by quasinormal modes. Using a physically motivated method to impose boundary conditions near the horizon and applying the so-called Boltzmann reflectivity, we compute the quasinormal modes of nonrotating exotic compact objects, as well as gravitational-wave echoes. We also investigate the detectability of these echoes in current and future detectors and prospects for parameter estimation.

We investigate a puzzle in the recent thermodynamics of scalar-tensor gravity, in which general relativity is a zero-temperature state of equilibrium and scalar-tensor gravity is the nonequilibrium configuration of an effective dissipative fluid. A stealth solution of Brans-Dicke gravity with constant positive temperature is shown to be analogous to a metastable state for the effective fluid and to suffer from an instability. The stability analysis employs a version of the Bardeen-Ellis-Bruni-Hwang gauge-invariant formalism for cosmological perturbations adapted to modified gravity. The metastable state is destroyed by tensor perturbations.

In the context of general relativity, both energy and linear-momentum constraints lead to the same equation for the evolution of the speed of free localized particles with fixed proper mass and structure in a homogeneous and isotropic Friedmann-Lemaître-Robertson-Walker universe. In this paper we extend this result by considering the dynamics of particles and fluids in the context of theories of gravity nonminimally coupled to matter. We show that the equation for the evolution of the linear momentum of the particles may be obtained irrespective of any prior assumptions regarding the form of the on-shell Lagrangian of the matter fields. We also find that consistency between the evolution of the energy and linear momentum of the particles requires that their volume-averaged on-shell Lagrangian and energy-momentum tensor trace coincide (${\mathcal{L}}_{\mathrm{on}\text{−}\mathrm{shell}}=T$). We further demonstrate that the same applies to an ideal gas composed of many such particles. This result implies that the two most common assumptions in the literature for the on-shell Lagrangian of a perfect fluid (${\mathcal{L}}_{\mathrm{on}\text{−}\mathrm{shell}}=\mathcal{P}$ and ${\mathcal{L}}_{\mathrm{on}\text{−}\mathrm{shell}}=-\rho$, where $\rho$ and $\mathcal{P}$ are the proper density and pressure of the fluid, respectively) do not apply to an ideal gas, except in the case of dust (in which case $T=-\rho$).

One of the important open questions in high-energy physics is to understand the lack of evidence of the Kalb-Ramond (KR) field, in particular in present day cosmology. In this paper we aim to address this issue by showing that a bounce scenario in the evolution of the Universe strongly advocates their elusiveness, even if their energy density was very large to start with. We consider the Kalb-Ramond field and its effects in the context of generalized teleparallel gravity in ($3+1$) dimensions. Teleparallel gravity is a description of gravitation in which the tetrads are the dynamical degrees of freedom, and the torsion arising from fields with spin are accommodated naturally as field strength tensors. In order to describe the coupling prescription, we address the correct generalization of the Fock-Ivanenko derivative operator for an $n$-form tensor field. By varying with respect to the tetrads, this rank-2 field is shown to source the teleparallel equivalent of Einstein’s equations. We study the possibility of reproducing two well-known cosmological bounce scenarios; namely, symmetric bounce and matter bounce in four-dimensional spacetime with the Friedmann-Lemaître-Robertson-Walker metric, and observe that the solution requires the KR field energy density to be localized near the bounce. The crucial result in our work is that this feature also naturally explains the lack of cosmological evidence of the rank-2 field in the present day Universe for the matter-bounce scenario. Thus, among the bouncing cosmologies, the latter is favored over the former.

In this work we investigate the possibility that dark matter and (massive) neutrinos can interact via a simple, constant cross section. Building on previous numerical efforts, we constrain this model with Cosmic Microwave Background, Baryon Acoustic Oscillations, and, in particular, Lyman-$\alpha$ data. We find that the latter hint to a significant departure from $\mathrm{\Lambda }\mathrm{CDM}$, with a preference for an interaction strength about $3\sigma$ away from zero. We trace the origin of this preference back to the additional tilt that the interacting scenario can imprint on the Lyman-$\alpha$ flux power spectrum, solving a well-known tension in the determination of this quantity between early-time and Lyman-$\alpha$ probes. Future work including complementary Lyman-$\alpha$ data as well as dedicated numerical simulations will be crucial in order to test these results.

We study the properties of the gravitational-wave (GW) emission between ${10}^{-5}$ and 50 Hz (which we refer to as low-frequency emission) from core-collapse supernovae, in the context of studying such signals in laser interferometric data as well as performing multimessenger astronomy. We pay particular attention to the GW linear memory, which is when the signal amplitude does not return to zero after the GW burst. Based on the long-term simulation of a core-collapse supernova of a solar-metallicity star with a zero-age main sequence mass of 15 solar masses, we discuss the spectral properties, the memory’s dependence on observer position, and the polarization of low-frequency GWs from non- (or slowly) rotating core-collapse supernovae. We make recommendations on the angular spacing of the orientations needed to properly produce results that are averaged over multiple observer locations by investigating the angular dependence of the GW emission. We propose semianalytical models that quantify the relationship between the bulk motion of the supernova shock wave and the GW memory amplitude. We discuss how to extend neutrino-generated GW signals from numerical simulations that are terminated before the neutrino emission has subsided. We discuss how the premature halt of simulations and the nonzero amplitude of the GW memory can induce artifacts during the data analysis process. Lastly, we also investigate potential solutions and issues in the use of taperings for both ground- and space-based interferometers.

We use coreas simulations to study the ratio of geomagnetic and Askaryan radio emission from cosmic-ray air showers at the location of the south pole. The fraction of Askaryan emission relative to the total emission is determined by the polarization of the radio signal at the time of its peak amplitude. We find that the relative Askaryan fraction has a radial dependence increasing with the distance from the shower axis—with a plateau around the Cherenkov ring. We further find that the Askaryan fraction depends on shower parameters like the zenith angle and the distance to the shower maximum. While these dependencies are in agreement with earlier studies, they have not yet been utilized to determine the depth of the shower maximum, $X_{\max }$, based on the Askaryan fraction. Fitting these dependencies with a polynomial model, we arrive at an alternative method to reconstruct $X_{\max }$ using a measurement of the Askaryan fraction and shower geometry as input. Depending on the measurement uncertainties of the Askaryan fraction, this method provides a measurement of $X_{\max }$ with a resolution similar to other methods of reconstructing $X_{\max }$ from radio observables. Although existing template methods give superior resolution, they are more computationally intensive. Consequently, the use of polarization to extract the Askaryan fraction of the radio signal should be considered as an additional input observable in future generations of template-fitting reconstruction and other multivariate approaches for measuring $X_{\max }$.

An event generation framework is presented that enables the automatic simulation of events for next-generation neutrino experiments in the Standard Model or extensions thereof. The new generator combines the calculation of the leptonic current based on an automated matrix element generator and the computation of the hadronic current based on a state-of-the-art nuclear physics model. The approach is validated in Standard Model simulations for electron scattering and neutrino scattering. Furthermore, the first fully differential neutrino trident production results are shown in the quasielastic region.

We study several aspects of the quantum structure of the minimal potentially realistic renormalizable SO(10) Higgs model in which the $\mathbf{45}\oplus \mathbf{126}$ scalars spontaneously break the symmetry down to the Standard Model (SM) group $\mathrm{SU}(3{)}_c\times \mathrm{SU}(2{)}_L\times \mathrm{U}(1{)}_Y$. With complete information about the one-loop corrections to the masses of all scalars in the theory and the one-loop beta functions governing the running of all dimensionless scalar self-couplings, the domains of the parameter space where the model can be treated perturbatively are established, along with improved bounds from the requirements of the SM vacuum stability and gauge coupling unification. We demonstrate that the model is fully consistent and potentially realistic only in very narrow regions of the parameter space corresponding to the breaking chains with well-pronounced $\mathrm{SU}(4{)}_C\times \mathrm{SU}(2{)}_L\times \mathrm{U}(1{)}_R$ and $\mathrm{SU}(3{)}_c\times \mathrm{SU}(2{)}_L\times \mathrm{SU}(2{)}_R\times \mathrm{U}(1{)}_{B-L}$ intermediate symmetries, with a clear preference for the former case. Barring accidental fine-tunings in the scalar sector, this makes it possible to provide a very sharp prediction for the position of the unification scale and the value of the associated gauge coupling, with clear implications for the phenomenology of grand unified models based on this structure.

We employ the chiral quark-soliton model and the heavy quark symmetry to describe spectra of charm and beauty baryons. Heavy baryons can be classified according to the SU(3) representations of the light sector. We argue that recently discovered ${\mathrm{\Xi }}_b$ states can be interpreted as negative-parity excited antitriplets or sextets, and the ${\mathrm{\Sigma }}_b$ states as negative-parity sextets. Consequences of such assignments for the decay patterns are discussed and also predictions of masses of the yet unmeasured sextet members are given.

There are eighteen possibly existing $D^{(*)}{\overline{D}}^{(*)}$, $D^{(*)}{\overline{K}}^{(*)}$, and $D^{(*)}{D}_s^{(*)-}$ hadronic molecular states. We construct their corresponding interpolating currents and calculate their decay constants using QCD sum rules. Based on these results, we calculate their relative production rates in $B$ and $B^{*}$ decays through the current algebra, and calculate their relative branching ratios through the Fierz rearrangement, as summarized in Table III. Our results support the interpretations of the $X(3872)$, $Z_c(3900{)}^0$, $Z_c(4020{)}^0$, and $X_0(2900)$ as the molecular states $D{\overline{D}}^{*}$ of $J^{PC}=1^{++}$, $D{\overline{D}}^{*}$ of $J^{PC}=1^{+-}$, $D^{*}{\overline{D}}^{*}$ of $J^{PC}=1^{+-}$, and $D^{*}{\overline{K}}^{*}$ of $J^P=0^{+}$, respectively. Our results also suggest that the $Z_{cs}(3985{)}^{-}$, $Z_{cs}(4000{)}^{+}$, and $Z_{cs}(4220{)}^{+}$ are strange partners of the $X(3872)$, $Z_c(3900{)}^0$, and $Z_c(4020{)}^0$, respectively. In the calculations we estimate the lifetime of a weakly coupled composite particle $A=|BC⟩$ to be $1/t_A\approx 1/t_B+1/t_C+{\mathrm{\Gamma }}_{A\to BC}+\cdots$, with $\cdots$ partial widths of other possible decay channels.

In this paper, the $IJ=00$, 11, 20 partial wave $\pi \pi$ scattering phase shifts determined by the lattice QCD approach are analyzed by using a novel dispersive solution of the S-matrix, i.e., the Peking University representation, in which the unitarity and analyticity of scattering amplitudes are automatically satisfied and the phase shifts are conveniently decomposed into the contributions of the cuts and various poles, including bound states, virtual states and resonances. The contribution of the left-hand cut is estimated by the $SU(2)$ chiral perturbation theory to $\mathcal{O}(p^4)$. The Balanchandran-Nuyts-Roskies relations are considered as constraints to meet the requirements of the crossing symmetry. It is found that the $IJ=00$ $\pi \pi$ scattering phase shifts obtained at $m_{\pi }=391\mathrm{MeV}$ by Hadron Spectrum Collaboration (HSC) reveal the presence of both a bound state pole and a virtual state pole below the $\pi \pi$ threshold rather than only one bound state pole for the $\sigma$. To reproduce the lattice phase shifts at $m_{\pi }=391\mathrm{MeV}$, a virtual-state pole in the $IJ=20$ channel is found to be necessary in order to balance the left-hand cut effects from the chiral amplitudes. Similar discussions are also carried out for the lattice results with $m_{\pi }=236\mathrm{MeV}$ from HSC. The observed behaviors of the pole positions with respect to the variation of the pion masses can provide deep insights into our understanding of the dynamical origin of $\sigma$ resonance.

Monte Carlo (MC) generators are crucial for analyzing data in particle collider experiments. However, often even a small mismatch between the MC simulations and the measurements can undermine the interpretation of the results. This is particularly important in the context of LHC searches for rare physics processes within and beyond the standard model (SM). One of the ultimate rare processes in the SM currently being explored at the LHC, $pp\to t\overline{t}t\overline{t}$ with its large multidimensional phase-space is an ideal testing ground to explore new ways to reduce the impact of potential MC mismodeling on experimental results. We propose a novel statistical method capable of disentangling the 4-top signal from the dominant backgrounds in the same-sign dilepton channel, while simultaneously correcting for possible MC imperfections in modeling of the most relevant discriminating observables—the jet multiplicity distributions. A Bayesian mixture of multinomials is used to model the light-jet and $b$-jet multiplicities under the assumption of their conditional independence. The signal and background distributions generated from a deliberately mistuned MC simulator are used as model priors. The posterior distributions, as well as the signal and background fractions, are then learned from the data using Bayesian inference. We demonstrate that our method can mitigate the effects of large MC mismodelings in the context of a realistic $t\overline{t}t\overline{t}$ search, leading to corrected posterior distributions that better approximate the underlying truth-level spectra.

We study the holographic realization of optimized correlation measures—measures of quantum correlation that generalize elementary entropic formulas—in two-dimensional thermal states dual to spacetimes with a black hole horizon. We consider the symmetric bipartite optimized correlation measures: the entanglement of purification, Q-correlation, R-correlation, and squashed entanglement, as well as the mutual information, a nonoptimized correlation measure, and identify the bulk surface configurations realizing their geometric duals over the parameter space of boundary region sizes and the black hole radius. This parameter space is divided into phases associated with given topologies for these bulk surface configurations, and first-order phase transitions occur as a new topology of bulk surfaces becomes preferred. The distinct phases can be associated with different degrees of correlation between the boundary regions and the thermal environment. The Q-correlation has the richest behavior, with a structure of nested optimizations leading to two topologically distinct bulk surface configurations being equally valid as geometric duals at generic points in the phase diagram.

Gravitational-wave observations of binary black holes provide a suitable arena to test the fundamental nature of gravity in the strong-field regime. Using the data of the inspiral of 29 events detected by the LIGO-Virgo observatories, we perform a theory-agnostic test of the Kerr hypothesis. We compute the leading-order deviation to the gravitational waves emitted in the frequency domain and provide constraints on two deformation parameters (${\delta }_1$ and ${\delta }_2$) belonging to a general class of axisymmetric non-Kerr black hole spacetimes proposed by Konoplya, Rezzolla, and Zhidenko. Our study shows that all the analyzed events are consistent with the Kerr hypothesis. The LIGO-Virgo data provide stronger constraints on ${\delta }_1$ and ${\delta }_2$ than those obtained in our previous studies with x-ray data, while, on the other hand, they cannot constrain the other deformation parameters of the Konoplya-Rezzolla-Zhidenko metric (${\delta }_3$, ${\delta }_4$, ${\delta }_5$, and ${\delta }_6$).

The $\mathrm{\Lambda }\mathrm{CDM}$ prediction of $S_8\equiv {\sigma }_8({\mathrm{\Omega }}_m/0.3{)}^{0.5}$—where ${\sigma }_8$ is the root mean square of matter fluctuations on an $8h^{-1}\mathrm{Mpc}$ scale—once calibrated on Planck cosmic microwave background data is $2-3\sigma$ lower than its direct estimate by a number of weak lensing surveys. In this paper, we explore the possibility that the “$S_8$ tension” is due to a fractional contribution of nonthermal hot dark matter (HDM) to the energy density of the Universe leading to a power suppression at small scales in the matter power spectrum. Any HDM model can be characterized by its effective mass $m_{\mathrm{sp}}^{\mathrm{eff}}$ and its contribution to the relativistic degrees of freedom at cosmic microwave background decoupling $\mathrm{\Delta }{N}_{\mathrm{eff}}$. Taking the specific example of a sterile particle produced from the decay of the inflaton during an early matter-dominated era, we find that the tension can be reduced below $2\sigma$ from Planck data only, but it does not favor a nonzero $\{m_{\mathrm{sp}}^{\mathrm{eff}},\mathrm{\Delta }{N}_{\mathrm{eff}}\}$. In combination with a measurement of $S_8$ from $\mathrm{KiDS}1000+\mathrm{BOSS}+2\mathrm{dfLenS}$, the $S_8$ tension would hint at the existence of a particle of mass $m_{\mathrm{sp}}^{\mathrm{eff}}\simeq 0.67_{-0.48}^{+0.26}\mathrm{eV}$ with a contribution to $\mathrm{\Delta }{N}_{\mathrm{eff}}\simeq 0.06\pm 0.05$. However, Pantheon and BOSS $\mathrm{BAO}/f{\sigma }_8$ data restricts the particle mass to $m_{\mathrm{sp}}^{\mathrm{eff}}\simeq 0.48_{-0.36}^{+0.17}$ and contribution to $\mathrm{\Delta }{N}_{\mathrm{eff}}\simeq 0.046_{-0.031}^{+0.004}$. We discuss implications of our results for other canonical nonthermal HDM models—the Dodelson-Widrow model and a hidden sector model of a thermal sterile particle with a different temperature. We report competitive results on such hidden sector temperature that might have interesting implications for particle physics model building, in particular connecting the $S_8$ tension to the longstanding short baseline oscillation anomaly.