In this work, we study the quasi-two-body decays $B_c\to K^{*}h\to K\pi h(h=D,D_s,K,\pi ,\eta ,{\eta }^{\prime })$ in the perturbative QCD (PQCD) approach. The two-meson distribution amplitudes ${\mathrm{\Phi }}_{K\pi }^{\text{P-wave}}$ are introduced to describe the final-state interactions of the $K\pi$ pair, which involve the timelike form factors $F_{K\pi }(s)$ parametrized by the relativistic Breit-Wigner function and the Gegenbauer polynomials. We calculate the branching ratios for these quasi-two-body decays, from which one can obtain the branching ratios for the corresponding two-body decays under the narrow width approximation relation. We find that $B_c^{+}\to K^{*+}{D}^0$ and $B_c^{+}\to K^{*0}{D}^{+}$ have the largest branching ratios, which can reach up to ${10}^{-6}$, while the branching ratios for other two-body decays are very small and only about ${10}^{-8}-{10}^{-7}$. As we expected, the branching ratios of the pure annihilation decays are usually small, while in our considered such type of decays, the channel $B_c^{+}\to {\overline{K}}^{*0}{K}^{+}$ has the largest branching ratio, which is near ${10}^{-6}$. These results are consistent with the previously PQCD calculations obtained in the two-body framework, which can be tested by future LHCb experiments. For the decays $B_c^{+}\to K^{*+}{D}^0\to K^0{\pi }^{+}{D}^0$, $B_c^{+}\to K^{*0}{D}^{+}\to K^{+}{\pi }^{-}{D}^{+}$, and $B_c^{+}\to {\overline{K}}^{*0}{D}_s^{+}\to K^{-}{\pi }^{+}{D}_s^{+}$, we also calculate their direct $CP$ violations and find that $A_{CP}(B_c^{+}\to K^{*+}{D}^0\to K^0{\pi }^{+}{D}^0)=(-{14.6}_{-1.1}^{+9.2})\%$ is the largest one, which is possible measured by the present LHCb experiments. For the pure annihilation type decays, there is no $CP$ violation, because only the tree operators are involved. Furthermore, we give the differential distributions of the branching ratios and the direct $CP$ violations in the $K\pi$ invariant mass $\omega$ for the decays $B_c\to K^{*}{D}_{(s)}\to K\pi D_{(s)}$.

We study the impact of LHC forward-backward asymmetry (AFB) measurements at high invariant mass in the Drell-Yan process on probes of semileptonic four-fermion operators in the Standard Model effective field theory (SMEFT). In particular, we study whether AFB measurements can resolve degeneracies in the Wilson coefficient parameter space that appear when considering invariant-mass and rapidity measurements alone. We perform detailed fits of the available high-energy and high-luminosity ATLAS and CMS data for both invariant-mass distributions and AFB. While each type of measurement separately exhibits degeneracies, combining them removes these blind spots in some cases. In other situations, it does not, highlighting the importance of incorporating future datasets from other experiments to fully explore this sector of the SMEFT. We investigate the impact of contributions quadratic in the Wilson coefficients on the description of Drell-Yan data and discuss when such terms are important in joint fits of the AFB and invariant-mass data.

We study electromagnetic radiation by a fast particle carrying electric charge in chiral medium. The medium is homogeneous and isotropic and supports the chiral magnetic current which renders the fermion and photon states unstable. The instability manifests as the chirality-dependent resonances in the bremsstrahlung cross section, which enhance the energy loss in the chiral medium. We compute the corresponding cross sections in the single scattering approximation and derive the energy loss in the high-energy approximation.

Beam dumps and fixed-target experiments have been very sensitive probes of such particles and other physics beyond the Standard Model by considering the production of new states from the primary interaction in the beam dump. In a proton beam dump, there are many secondary interactions taking place in electromagnetic showers which may be additional production channels for pseudoscalar bosons or axionlike particles (ALPs). The targetless configuration of the MiniBooNE experiment, which collected data from $1.86\times {10}^{20}$ protons impinging directly on the steel beam dump, is an excellent test of sensitivity to these production channels of ALPs in the MeV mass region. Using the null observation of the MiniBooNE dump mode data, we set new constraints on ALPs coupling to electrons and photons produced through a multitude of channels and detected via both scattering and decays in the MiniBooNE detector volume. We find that the null result rules out parameter space that was previously unconstrained by laboratory probes in the 10–100 MeV mass regime for both electron and photon couplings. Lastly, we make the case for performing a dedicated analysis with $1.25\times {10}^{20}$ protons on target of data collected by the ArgoNeuT experiment, which we show to have complementary sensitivity and set the stage for future searches.

We study how vacuum neutrino oscillations can be affected by a causal, nonlinear and state-dependent modification of quantum field theory that may be interpreted using the many-worlds formulation of quantum mechanics. The effect is induced by a Higgs-neutrino Yukawa interaction that causes a nonlinear interference between the neutrino mass eigenstates. This leads to a tiny change in the oscillation pattern of light, active neutrinos. At large baselines where the oscillations disappear, the nonlinear effect is also suppressed and does not source correlations between the mass eigenstates once they are entangled with the environment. Our example provides a way to compute effects of nonlinear quantum mechanics and field theory that may probe the possible physical reality of many worlds.

We study the effects of discretization on the U(1) symmetric XY model in two dimensions using the higher order tensor renormalization group approach. Regarding the $Z_N$ symmetric clock models as specific discretizations of the XY model, we compare those discretizations to ones from truncations of the tensor network formulation of the XY model based on a character expansion and focus on the differences in their phase structure at low temperatures. We also divide the tensor network formulations into core and interaction tensors and show that the core tensor has the dominant influence on the phase structure. Lastly, we examine a perturbed form of the XY model that continuously interpolates between the XY and clock models. We examine the behavior of the additional phase transition caused by the perturbation as the magnitude of perturbation is taken to zero. We find that this additional transition has a nonzero critical temperature as the perturbation vanishes, suggesting that even small perturbations can have a significant effect on the phase structure of the theory.

We present a novel method to determine on the lattice both the real and imaginary parts of complex electroweak amplitudes involving two external currents and a single hadron or the QCD vacuum in the external states. The method is based on the spectral representation of the relevant time-dependent correlation functions and, by extending the range of applicability of other recent proposals built on the same techniques, overcomes the difficulties related to the analytic continuation from Minkowskian to Euclidean time, arising when intermediate states with energies smaller than the external states contribute to the amplitude. In its simplest form, the method relies on the standard $iϵ$ prescription to regularize the Feynman integrals and at finite $ϵ$ it requires to verify the condition $1/L\ll ϵ\ll \mathrm{\Delta }(E)$, where $L$ is the spatial extent of the lattice and, for any given energy $E$, $\mathrm{\Delta }(E)$ represents the typical size of the interval around $E$ in which the hadronic amplitude is significantly varying. In order to illustrate the effectiveness of this approach in a realistic case, we apply the method to evaluate nonperturbatively the hadronic amplitude contributing to the radiative leptonic decay $D_s\to \ell {\nu }_{\ell }{\gamma }^{*}$, working for simplicity with a single lattice ensemble at fixed volume and lattice spacing.

In the present work we investigate the source of azimuthal asymmetry for nuclear collision using a model that contemplates particles produced in the initial hard collisions and the collective effects described by a blast-wave-like expansion. The latter is described by the relaxation time approximation of the Boltzmann transport equation. The parameters regarding collective flow and asymmetry are fitted by the experimental data from the $p_T$ spectrum and $v_2$ for PbPb and XeXe collisions at different centrality classes. As a by-product the ratio of final elliptic flow with the initial anisotropy, $v_2/{\epsilon }_2$, and the average transverse momentum are predicted.

Heavy quarks are excellent probes to understand the hot and dense medium formed in ultra-relativistic collisions. In a hadronic medium, studying the transport properties, e.g. the drag ($\gamma$), momentum diffusion ($B_0$), and spatial diffusion ($D_s$) coefficients of open charmed hadrons can provide useful information about the medium. Moreover, the fluctuations of charmed hadrons can help us to locate the onset of their deconfinement. In this work, we incorporate attractive and repulsive interactions in the well-established van der Waals hadron resonance gas model (VDWHRG) and study the diffusion and fluctuations of charmed hadrons. This study helps us understand the importance of interactions in the system, which affect both the diffusion and fluctuations of charmed hadrons.

The recently observed strange pentaquark candidate, $P_{\psi s}^{\mathrm{\Lambda }}(4338{)}^0$, is investigated to provide information about its nature and substructure. To this end, its mass and width through the decay channels $P_{\psi s}^{\mathrm{\Lambda }}(4338{)}^0\to J/\psi \mathrm{\Lambda }$ and $P_{\psi s}^{\mathrm{\Lambda }}(4338{)}^0\to {\eta }_c\mathrm{\Lambda }$ are calculated by applying two- and three-point QCD sum rules, respectively. The state is considered as a ${\mathrm{\Xi }}_c\overline{D}$ meson-baryon molecular structure with spin-parity quantum numbers $J^P={\frac{1}{2}}^{-}$. The obtained mass, $m_{P_{\psi s}^{\mathrm{\Lambda }}(4338{)}^0}=4338\pm 130\mathrm{MeV}$, and width, ${\mathrm{\Gamma }}_{P_{\psi s}^{\mathrm{\Lambda }}(4338{)}^0}=10.40\pm 1.93\mathrm{MeV}$, are consistent with the experimental data within the presented uncertainties. This allows us to assign a ${\mathrm{\Xi }}_c\overline{D}$ molecular structure of $J^P={\frac{1}{2}}^{-}$ for the $P_{\psi s}^{\mathrm{\Lambda }}(4338{)}^0$ state.

The nonleptonic decay ${\mathrm{\Xi }}_c^0\to {\mathrm{\Lambda }}_c^{+}{\pi }^{-}$ with $\mathrm{\Delta }C=0$ is systematically studied in the framework of the covariant confined quark model accounting for both short and long distance effects. The short distance effects are induced by four topologies of external and internal weak $W^{\pm }$ exchange, while long distance effects are saturated by an inclusion of the so-called pole diagrams with an intermediate ${\frac{1}{2}}^{+}$ and ${\frac{1}{2}}^{-}$ baryon resonances. The contributions from ${\frac{1}{2}}^{+}$ resonances are calculated straightforwardly by accounting for single charmed ${\mathrm{\Sigma }}_c^0$ and ${\mathrm{\Xi }}_c^{\prime +}$ baryons whereas the contributions from ${\frac{1}{2}}^{-}$ resonances are calculated by using the well-known soft-pion theorem in the current-algebra approach. It allows to express the parity-violating $S$-wave amplitude in terms of parity-conserving matrix elements. It is found that the contribution of external and internal $W$-exchange diagrams is significantly suppressed by more than one order of magnitude in comparison with data. The pole diagrams play the major role to get consistency with experiment.

We present a measurement of time-dependent rate asymmetries in $B^0\to \varphi K_S^0$ decays to search for non-standard-model physics in $b\to q\overline{q}s$ transitions. The data sample is collected with the Belle II detector at the SuperKEKB asymmetric-energy $e^{+}{e}^{-}$ collider in 2019–2022 and contains $(387\pm 6)\times {10}^6$ bottom-antibottom mesons from $\mathrm{\Upsilon }(4S)$ resonance decays. We reconstruct $162\pm 17$ signal events and extract the charge-parity ($CP$) violating parameters from a fit to the distribution of the proper-decay-time difference of the two $B$ mesons. The measured direct and mixing-induced $CP$ asymmetries are $C=-0.31\pm 0.20\pm 0.05$ and $S=0.54\pm 0.26_{-0.08}^{+0.06}$, respectively, where the first uncertainties are statistical and the second are systematic. The results are compatible with the $CP$ asymmetries observed in $b\to c\overline{c}s$ transitions.

If the temperature of the hot thermal plasma in the early Universe was within a few orders of magnitude of the Planck scale $M_{\mathrm{Pl}}$, then the hoop conjecture predicts the formation of microscopic black holes from particle collisions in the plasma. Although these evaporated instantly, they would have left behind a relic abundance of all stable degrees of freedom which couple to gravity. Here we show that, upon minimal assumptions of a high reheat temperature and semiclassical black hole dynamics, this process could have produced the relic abundance of dark matter observed today for a particle mass anywhere in the range of $100\mathrm{keV}\lesssim m_{\mathrm{dm}}<M_{\mathrm{Pl}}$, though it could be subdominant to graviton-mediated freeze-in above $m_{\mathrm{dm}}\sim \mathrm{MeV}$. The production mechanism does not rely on any additional assumptions about nongravitational dark matter-Standard Model interaction.

In an odd-dimensional spacetime, gravity can be formulated as a proper gauge theory based on the Chern-Simons action for a suitable gauge group. Performing dimensional reduction, one obtains, as an effective theory, Chamseddine’s even-dimensional topological gravity with the reduced gauge symmetry. This theory involves a multiplet of scalar fields that appear as a result of the dimensional reduction, and it is topological in the sense that its action does not depend on the metric. Focusing primarily on the four-dimensional case, we use the holographic dictionary to compute one-point correlation functions of the relevant boundary operators and find that the spin-current can have a nonzero expectation value in the dual quantum field theory. We also consider the generalized holographic Weyl anomaly and find that it vanishes. Finally, we propose a way of computing two-point correlation functions using the gravitational Wilson lines.

Using the recently derived higher-spin gravitational Compton amplitude from low-energy analytically continued ($a/Gm\gg 1$) solutions of the Teukolsky equation for the scattering of a gravitational wave off the Kerr black hole, observables for nonradiating super-extremal Kerr binary systems at second post-Minkowskian (PM) order and up to sixth order in spin are computed. The relevant 2PM amplitude is obtained from the triangle-leading singularity in conjunction with a generalization of the holomorphic classical limit for massive particles with spin oriented in generic directions. Explicit results for the 2PM eikonal phase written for both covariant and canonical spin supplementary conditions—CovSSC and CanSSC respectively—as well as the 2PM linear impulses and individual spin kicks in the CanSSC are presented. The observables reported in this letter are expressed in terms of generic contact deformations of the gravitational Compton amplitude, which can then be specialized to Teukolsky solutions. In the latter case, the resulting 2PM observables break the newly proposed spin-shift symmetry of the 2PM amplitude starting at the fifth order in spin. Aligned spin checks as well as the high-energy behavior of the computed observables are discussed.

In prerecombination early dark energy (EDE) resolutions of the Hubble tension, the rise of Hubble constant value $H_0$ is usually accompanied with the exacerbation of so-called $S_8$ tension. Inspired by the swampland conjecture, we investigate what if a fraction $f_{*}$ of dark matter is coupled to EDE, $m_{\mathrm{cdm}}\sim \exp (-c\frac{|\mathrm{\Delta }{\varphi }_{\mathrm{ede}}|}{M_{pl}})$ with $c\sim \mathcal{O}(1)$. We perform the Markov chain Monte Carlo analysis for the relevant EDE models with PlanckCMB, BAO, Pantheon and SH0ES dataset, as well as DES-Y1 data, and find that such a fraction helps to alleviate the $S_8$ tension. However, though $c\gtrsim 0.1$ is allowed for a very small $f_{*}$, which suggests that a small fraction of dark matter has ever faded with EDE, $c\sim 0$ is also consistent.

Time-delay interferometry (TDI) is the data processing technique that cancels the large laser phase fluctuations affecting the one-way Doppler measurements made by unequal-arm space-based gravitational wave interferometers. In a previous publication we derived TDI combinations that exactly cancel the laser phase fluctuations up to first order in the interspacecraft velocities. This was done by interfering two digitally synthesized optical beams propagating a number of times clockwise and counterclockwise around the array. Here we extend that approach by showing that the number of loops made by each beam before interfering corresponds to a specific higher-order TDI space. In it the cancellation of laser noise terms that depend on the acceleration and higher-order time derivatives of the interspacecraft light-travel times is achieved exactly. Similarly to what we proved for the second-generation TDI space, elements of a specific higher-order TDI space can be obtained by first “lifting” the basis ($\alpha$, $\beta$, $\gamma$, $X$) of the first-generation TDI space to the higher-order space of interest and then taking linear combinations of them with coefficients that are polynomials of the six delays operators. Higher-order TDI might be required by future interplanetary gravitational wave missions whose interspacecraft distances vary appreciably with time, in particular, relative velocities are much larger than those of currently planned arrays.

The Electron-Ion Collider (EIC) provides unique opportunities in searching for new physics through its high center-of-mass energy and coherent interactions of large nuclei. We examine how light weakly interacting vector bosons from a variety of models can be discovered or constrained, over significant parts of their parameter space, through clean displaced vertex signals at the EIC. Our results indicate that the searches we propose favorably compare with or surpass existing experimental projections for the models examined. The reach for the new physics that we consider can be markedly improved if “far backward” particle identification capabilities are included in the EIC detector complex.

A model with a half-boson degree of freedom per lattice site in one dimension is developed. The boson is protected from developing a gap by translation symmetry; while the left movers are at zero quasimomentum, the associated right movers are at the midpoint of the quasimomentum period. The model has different properties depending on if a periodic lattice has an even or an odd number of sites and similar features are found for open boundary conditions. A special case of the nonlinear half-boson model where even and odd lattice sites contribute differently to the Hamiltonian gives rise to the Toda chain and a more symmetric generalization of the Toda chain is found. Upon periodic identifications of the half-bosons degrees of freedom under a shift, the total Hilbert space has a finite dimension and can be encoded in finitely many qubits per unit length. This way one finds interesting critical-spin chains, examples of which include the critical Ising model in a transverse magnetic field and the 3-state Potts model at criticality. Extensions to higher dimensions are considered. Models obtained this way automatically produce dynamical systems of gapless fractons.