In this work, we present the first results on the gluon parton distribution of the kaon from lattice quantum chromodynamics. We carry out the lattice calculation at pion mass around 310 MeV and two lattice spacings, 0.15 and 0.12 fm, using $2+1+1$-flavor HISQ ensembles generated by MILC Collaboration. The kaon correlators are calculated using clover fermions and momentum-smearing sources with maximum boost momentum around 2 GeV and high statistics (up to 324,000 measurements). We study the dependence of the resulting reduced Ioffe-time pseudodistributions at multiple boost momenta and lattice spacings. We then extract the kaon gluon distribution function in the $\overline{\mathrm{MS}}$ scheme at $\mu =2\mathrm{GeV}$, neglecting the mixing between the gluon and singlet-quark sectors. Our results at the smaller lattice spacing are consistent with phenomenological determinations.

We give an explicit proof for the locality of staggered overlap operators. The proof covers the original two flavor construction by Adams as well as a single flavor version. As in the case of Neuberger’s operator, an admissibility condition for the gauge fields is required.

Focusing on recent measurement of the $B^{+}\to D_s^{+}{D}_s^{-}{K}^{+}$ process given by the LHCb Collaboration, we propose that this newly observed near the $D_s^{+}{D}_s^{-}$ threshold enhancement can be due to the contribution of the ${\chi }_{c0}(2P)$, which is a $P$-wave charmonium below the $D_s^{+}{D}_s^{-}$ threshold. By performing a combined fit to the measured $D_s^{+}{D}_s^{-}$, $D_s^{+}{K}^{+}$, and $D_s^{-}{K}^{+}$ invariant mass spectra, introducing the ${\chi }_{c0}(2P)$ can well reproduce the near threshold enhancement in the $D_s^{+}{D}_s^{-}$ invariant mass spectrum. When depicting the whole $D_s^{+}{D}_s^{-}$ invariant mass spectrum, the contributions from higher charmonium $\psi (4230)$ and charmoniumlike state $X_0(4140)$ are obvious. In addition, a charmed meson $D^{*}(3^3{S}_1)$ with mass around 3015 MeV is found to be important to depict the $D_s^{-}{K}^{+}$ invariant mass spectrum well. Especially, the importance of node effect of the spatial wave function of the ${\chi }_{c0}(2P)$ is revealed, by which the anomaly of the ratio $\mathrm{\Gamma }(X\to D^{+}{D}^{-})/\mathrm{\Gamma }(X\to D_s^{+}{D}_s^{-})$ indicated by LHCb can be explained well. Finally, our scenario of the newly observed enhancement structure resulting from the ${\chi }_{c0}(2P)$ is enforced.

In the present paper we study the photoproduction of various $S$-wave $B_c$ states, i.e., $B_c(1{{}^{1}S}_0)$, $B_c^{*}(1{{}^{1}S}_0)$, $B_c(2{{}^{1}S}_0)$, and $B_c^{*}(2{{}^{3}S}_1)$, at future $e^{+}{e}^{-}$ colliders within the framework of nonrelativistic QCD. Two sources of the initial photons can be realized in the production, i.e., the laser backscattering photon and the Weizäcker-Williams approximation photon. In addition to the direct photoproduction via the subprocess, $\gamma +\gamma \to B_c+b+\overline{c}$, we also calculate the resolved photoproduction via the subprocesses, $\gamma +g\to B_c+b+\overline{c}$ and $q+\overline{q}\to B_c+b+\overline{c}$ with $q=u$, $d$, $s$, $g$, respectively. Numerical results indicate that the contributions from the single resolved photoproduction are significant and even dominant at certain collision configuration. At the future high-energy and high-luminosity $e^{+}{e}^{-}$ colliders, the $B_c$ meson generated via the photoproduction mechanism is promisingly observable and can be well studied.

The mass spectrum of ${\pi }^{+}$ and ${\rho }^{+}$ mesons in the presence of a static uniform magnetic field $\overrightarrow{B}$ is studied within a two-flavor Nambu-Jona-Lasinio-like model. We improve previous calculations, taking into account the effect of Schwinger phases carried by quark propagators and using an expansion of meson fields in terms of the solutions of the corresponding equations of motion for nonzero $B$. It is shown that the meson polarization functions are diagonal in this basis. Our numerical results for the ${\rho }^{+}$ meson spectrum are found to disfavor the existence of a meson condensate induced by the magnetic field. In the case of the ${\pi }^{+}$ meson, $\pi$—$\rho$ mixing effects are analyzed for the meson lowest-energy state. The predictions of the model are compared with available lattice QCD results.

We analyze the photon-initiated processes for production of $e^{+}{e}^{-}$ pairs in proton-nucleus collisions at LHC energy, taking into account both elastic processes and proton dissociations in the low-mass region (LMR) and intermediate-mass region (IMR) as defined by the ALICE collaboration. The calculations are performed within the $k_{\mathrm{T}}$-factorization approach, including transverse momenta of intermediate photons. We discuss several differential distributions in invariant mass of both the leptons $M_{ll}$, pair rapidity $Y_{ll}$ and transverse momenta of the lepton pair $p_{t,ll}$. In addition, we present the two-dimensional distributions in ${\log }_{10}{x}_{Bj}$ and ${\log }_{10}{Q}^2$ and (${\log }_{10}W,{\log }_{10}{Q}^2$) the arguments of the deep-inelastic structure functions. All presented results were obtained with modern parametrizations of proton structure functions. Limiting to small invariant masses of dielectrons one tests structure functions in the nonperturbative region of small $Q^2$ and/or small $W$. We quantify difference for different parametrizations from the literature. We estimate gap survival factor and discuss experimental possibilities.

We have studied the transport coefficients as a tool to probe the collision integral appearing in the Boltzmann transport equation. For this purpose, we have estimated the transport coefficients (momentum: $\{\eta ,\zeta \}$, heat: $\{\kappa \}$, and charge: $\{{\sigma }_{\mathrm{el}}\}$) in the kinetic theory approach with the collision integrals in Bhatnagar-Gross-Krook (BGK) and relaxation-time (RT) approximations and ask whether we can distinguish between the two collision integrals. For example, $\eta$ gets enhanced while $\zeta$ gets reduced with respect to RT. As a corollary, we then investigate the interplay among the aforesaid transport coefficients, viz. fluidity and transition point of QCD medium by evaluating the ratios, $\eta /s$ and $\zeta /s$, respectively, nature of flow (Reynolds number, RI), sound attenuation (Prandtl number, Pr), and competition between the momentum and charge diffusion ($\gamma$), etc. as further plausible tools to decipher the same. With BGK collision integral, the ratios $\eta /s$ (increase) and $\zeta /s$ (decrease) show opposite behavior, whereas Pr, RI, $\gamma$, and the ratio $\zeta /\eta$ get reduced with respect to RT. We then examine how a strong magnetic field modulates the impact of the collision integral, which, in a way, explores the dimensionality dependence of the transport phenomena, especially momentum transport because the quark dynamics is effectively restricted to 1D only and only the lowest Landau levels are populated. As a result, $\eta$ ($\zeta$) gets reduced (amplified), which will have ramifications on the ratios, viz. $\eta /s$ ($\zeta /s$) becomes smaller (larger), enhancement of Pr, $\gamma$, and $\zeta /\eta$, etc. In this study, the thermomagnetic medium effects have been incorporated by adopting a thermodynamically consistent quasiparticle model, where the medium-generated masses of the partons have been obtained from the pole of their resummed propagators calculated using perturbative thermal QCD in strong $B$.

In this work, we study the spin density matrix element ${\rho }_{00}$ of the $\varphi$ in the decay $J/\psi \to \eta \pi \varphi$. In previous studies, a band around 1.4 GeV on the ${\pi }^0\varphi$ distribution in Dalitz plot was reported by the BESIII Collaboration. This structure may be caused by the production of a resonance or the triangle singularity mechanism. We find that the predictions of the spin density matrix elements of the final $\varphi$ based on these mechanisms show distinct features. Thus the measurement of the spin density matrix elements of the $\varphi$ in this reaction may offer an alternative way to study the triangle singularity and to clarify the reaction mechanisms, i.e., resonance production or kinematic effects. This work also shows the potential of spin observables in studying kinematic singularities.

A refined investigation on light flavor meson-baryon scatterings is performed using a dynamical coupled-channel approach, the Jülich-Bonn model, that respects unitarity and analyticity constraints. The channel space of $\pi N$, $\pi \mathrm{\Delta }$, $\sigma N$, $\rho N$, $\eta N$, $K\mathrm{\Lambda }$, and $K\mathrm{\Sigma }$ is extended by adding the $\omega N$ final state. The spectra of $N^{*}$ and $\mathrm{\Delta }$ resonances are extracted in terms of complex poles of the scattering amplitudes, based on the result of a global fit to a worldwide collection of data, in the energy region from the $\pi N$ threshold to center-of-mass energy $z=2.3\mathrm{GeV}$. A negative value of the $\omega N$ elastic spin-averaged scattering length is extracted, questioning the existence of bound states of the $\omega$ meson in the nuclear matter.

We estimate kinematical higher-twist (up to twist 4) corrections to the ${\gamma }^{*}(q_1)\gamma (q_2)\to M(p_1)\overline{M}(p_2)$ amplitudes at large $Q^2=-q_1^2$ and small $s=(q_1+q_2{)}^2$, where $M$ is a scalar or pseudoscalar meson. This process is known to factorize at leading twist into a perturbatively calculable coefficient function and generalized distribution amplitudes (GDAs). The kinematical higher-twist contributions of order $s/Q^2$ and $m^2/Q^2$ turn out to be important in the cross section, considering the kinematics accessible at Belle and Belle II. We present numerical estimates for the cross section for ${\gamma }^{*}\gamma \to {\pi }^0{\pi }^0$ with the $\pi \pi$ GDA extracted from Belle measurements and with the asymptotic $\pi \pi$ GDA as inputs to study the magnitude of the kinematical corrections. To see how the target mass corrections of order $m^2/Q^2$ affect the cross section, we also perform the calculation for ${\gamma }^{*}\gamma \to \eta \eta$ by using a model $\eta \eta$ GDA. In the range $s>1{\mathrm{GeV}}^2$, the kinematical higher-twist corrections account for $\sim 15\%$ of the total cross section, an effect which is not negligible. Since $\pi \pi$ GDAs are the best way to access the pion energy-momentum tensor (EMT), our study demonstrates that an accurate evaluation of EMT form factors requires the inclusion of kinematical higher-twist contributions.

Inspired by the recent Hall C and GlueX measurements of $J/\psi$ photoproduction, a systematic analysis of the contribution of quantum anomalous energy (QAE) to the proton mass is carried out under the framework of the vector meson dominance model. The results show that the effective Pomeron model and the parametrized two gluon exchange model can explain the cross section of $J/\psi$ photoproduction well. Based on the predicted cross section values given by the two models, the distribution of the QAE contribution with the energy is extracted for the first time. Finally, the average value of the QAE contribution is estimated to be $(3.50\pm 0.70)\%$, which suggests that the QAE contribution to the proton mass is small. Accordingly, we compared this result with those of other groups and explored the causes for the differences.

We investigate the axial-vector transition form factors of the lowest-lying singly heavy baryons within the framework of the chiral quark-soliton model. We consider the linear $m_{\mathrm{s}}$ corrections, dealing with the strange current quark mass $m_{\mathrm{s}}$ as a small perturbation. Since we have various relations between different transitions because of isospin symmetry and flavor SU(3) symmetry breaking, only two axial-vector transition form factors are independent. We present the numerical results for these form factors. The effects of the flavor SU(3) symmetry breaking turn out tiny, so we neglect them. We also compute the decay rates for several strong decays of the singly heavy baryons and compare the results with the experimental data and those from other models. While the results for the ${\mathrm{\Sigma }}_c\to {\mathrm{\Lambda }}_c^{+}+\pi$ and ${\mathrm{\Sigma }}_c^{*}\to {\mathrm{\Lambda }}_c^{+}+\pi$ decays are slightly overestimated in comparison with the corresponding experimental data, those for the ${\mathrm{\Xi }}_c^{*}\to {\mathrm{\Xi }}_c+\pi$ are in remarkable agreement with the data.

Prompted by the recent Dresden-II reactor data, we examine its implications for the determination of the weak mixing angle, paying attention to the effect of the quenching function. We also determine the resulting constraints on the unitarity of the neutrino mixing matrix, as well as on the most general type of nonstandard neutral-current neutrino interactions.

The nonleptonic decays $B_{d,s}\to K^{*0}{\overline{K}}^{*0}$ are reanalyzed in perturbative QCD approach, which is based on the $k_{\mathrm{T}}$ factorization. In the Standard Model, the calculated branching fraction and longitudinal polarization fraction of $B_d\to K^{*0}{\overline{K}}^{*0}$ are in agreement with experimental measurements, while the predictions of $B_s\to K^{*0}{\overline{K}}^{*0}$ cannot agree with data simultaneously. The parameter that combines longitudinal polarization fractions and branching fractions is calculated to be $L_{K^{*}{\overline{K}}^{*0}}^{\mathrm{PQCD}}={12.7}_{-3.2}^{+5.6}$, which is also larger than that extracted from experimental measurements. We then study all observables by introducing a family nonuniversal $Z^{\prime }$ boson in $b\to sq\overline{q}$ transitions. In order to reduce the number of new parameters, we simplify the model as possible. It is found that with the fixed value ${\omega }_{B_s}=0.55$, these exists parameter space where all measurements, including the branching fraction, longitudinal polarization fraction, and $L_{K^{*}{\overline{K}}^{*0}}$-parameter, could be accommodated simultaneously. All our results and the small parameter space could be further tested in the running LHC experiment, Belle-II, and future high-energy colliders.

We construct a semi-inclusive lepton flavor universality (LFU) ratio, $R_{\mathrm{\Sigma }}$, to test $\mu /e$ universality in $b\to s{\ell }^{+}{\ell }^{-}$ transitions at $e^{+}{e}^{-}B$-meson factories. Combining different decay channels, this observable maximizes the sensitivity to possible LFU violations of short-distance origin, yet preserves a clean theoretical interpretation in the case of a deviation from its Standard Model prediction, $R_{\mathrm{\Sigma }}^{\mathrm{SM}}=1$.

Score-based generative models are a new class of generative algorithms that have been shown to produce realistic images even in high dimensional spaces, currently surpassing other state-of-the-art models for different benchmark categories and applications. In this work we introduce caloscore, a score-based generative model for collider physics applied to calorimeter shower generation. Three different diffusion models are investigated using the Fast Calorimeter Simulation Challenge 2022 dataset. caloscore is the first application of a score-based generative model in collider physics and is able to produce high-fidelity calorimeter images for all datasets, providing an alternative paradigm for calorimeter shower simulation.

In the past decades, numerous experiments have emerged to unveil the nature of dark matter, one of the most discussed open questions in modern particle physics. Among them, the Cryogenic Rare Event Search with Superconducting Thermometers (CRESST) experiment, located at the Laboratori Nazionali del Gran Sasso, operates scintillating crystals as cryogenic phonon detectors. In this work, we present first results from the operation of two detector modules which both have 10.46 g ${\mathrm{LiAlO}}_2$ targets in CRESST-III. The lithium contents in the crystal are ${}^6\mathrm{Li}$, with an odd number of protons and neutrons, and ${}^7\mathrm{Li}$, with an odd number of protons. By considering both isotopes of lithium and ${}^{27}\mathrm{Al}$, we set the currently strongest cross section upper limits on spin-dependent interaction of dark matter with protons and neutrons for the mass region between 0.25 and $1.5\mathrm{GeV}/c^2$.

We present a search for long-lived Higgs portal scalars (HPS) and heavy neutral leptons (HNL) decaying in the MicroBooNE liquid-argon time projection chamber. The measurement is performed using data collected synchronously with the neutrino beam from Fermilab’s Main Injector with a total exposure corresponding to $7.01\times {10}^{20}$ protons on target. We set upper limits at the 90% confidence level on the mixing parameter $|U_{\mu 4}{|}^2$ ranging from $|U_{\mu 4}{|}^2<12.9\times {10}^{-8}$ for Majorana HNLs with a mass of $m_{\mathrm{HNL}}=246\mathrm{MeV}$ to $|U_{\mu 4}{|}^2<0.92\times {10}^{-8}$ for $m_{\mathrm{HNL}}=385\mathrm{MeV}$, assuming $|U_{e4}{|}^2=|U_{\tau 4}{|}^2=0$ and HNL decays into ${\mu }^{\pm }{\pi }^{\mp }$ pairs. These limits on $|U_{\mu 4}{|}^2$ represent an order of magnitude improvement in sensitivity compared to the previous MicroBooNE result. We also constrain the scalar-Higgs mixing angle $\theta$ by searching for HPS decays into ${\mu }^{+}{\mu }^{-}$ final states, excluding a contour in the parameter space with lower bounds of ${\theta }^2<31.3\times {10}^{-9}$ for $m_{\mathrm{HPS}}=212\mathrm{GeV}$ and ${\theta }^2<1.09\times {10}^{-9}$ for $m_{\mathrm{HPS}}=275\mathrm{GeV}$. These are the first constraints on the scalar-Higgs mixing angle $\theta$ from a dedicated experimental search in this mass range.

In this paper, three things are done. First, we study from an algebraic point of view the infinite-dimensional Bondi-Metzner-Sachs (BMS)-like extensions of the Carroll algebra relevant to the asymptotic structure of the electric and magnetic Carrollian limits of Einstein gravity. In the course of this study we exhibit by the “Carroll-Galileo duality” a new infinite-dimensional BMS-like extension of the Galilean algebra and of its centrally extended Bargmann algebra. Second, we consider the electric Carrollian limit of the pure Einstein theory and indicate that more flexible boundary conditions than the ones that follow from just taking the limit of the Einsteinian boundary conditions are actually consistent. These boundary conditions lead to a bigger asymptotic symmetry algebra that involves spatial supertranslations depending on three functions of the angles (instead of one). Third, we turn to the Carrollian limit of the coupled Einstein-Yang-Mills system. An infinite-dimensional color enhancement of the gauge algebra is found in the electric Carrollian limit of the Yang-Mills field, which allows angle-dependent Yang-Mills transformations at spatial infinity, not available in the Einstein-Yang-Mills case prior to taking the Carrollian electric limit. This enhancement does not occur in the magnetic limit.

We study the thermodynamics of accelerating asymptotically anti–de Sitter black holes with scalar hair in four-dimensional Einstein-Maxwell-dilaton theories, which can be embedded in gauged supergravities for specific dilaton coupling constants. These accelerating black holes are described by charged dilaton C metrics, which have unique features but are almost unexplored before. Thermodynamics of slowly accelerating black holes is generalized to include scalar hair. We find that properly accounting for mixed boundary conditions for the scalar field leads to standard consistent first law and other thermodynamic relations. We compute the dual stress-energy tensor and the mass through holographic renormalization, which is associated with the boundary conditions of the scalar field. We also find that the conformal mass is the same as the holographic mass. Along the same line, we also obtain the thermodynamics of $U(1{)}^2$-charged accelerating black holes.