Experimental efforts toward the detection of the nonperturbative strong-field regime of the Breit-Wheeler pair creation process plan to combine incoherent sources of GeV $\gamma$ quanta and the coherent fields of tightly focused optical laser pulses. This endeavor calls for a theoretical understanding of how the pair yields depend on the applied laser field profile. We provide estimates for the number of produced pairs in a setup where the high-energy radiation is generated via bremsstrahlung. Attention is paid to the role of the transversal and longitudinal focusing of the laser field, along with the incorporation of a Gaussian pulse envelope. We compare our corresponding results with predictions from plane-wave models and determine the parameters of focused laser pulses which maximize the pair yield at fixed pulse energy. Besides, the impact of various super-Gaussian profiles for the laser pulse envelope and its transverse shape is discussed.

We present first results on the resummation of next-to-soft virtual (NSV) logarithms for the threshold production of pseudoscalar Higgs boson through gluon fusion at the LHC. These results are presented after resumming the NSV logarithms of the kind ${\log }^i(1-z)$ to $\overline{\mathrm{NNLL}}$ accuracy and matching them systematically to the fixed order NNLO cross sections. These results are obtained using collinear factorization, renormalization group invariance and recent developments in the NSV resummation techniques. The phenomenological implications of these NSV resummed results for 13 TeV LHC are studied and it is observed that these NSV logarithms are quite large. We also evaluate theory uncertainties and find that the renormalization scale uncertainties get reduced further with the inclusion of NSV corrections at various orders in QCD. We further study the impact of QCD corrections on mixed scalar-pseudoscalar states for different values of the mixing angle $\alpha$.

The Berry phase is analyzed for Weyl and Dirac fermions in a phase space representation of the worldline formalism. Kinetic theories are constructed for both at a classical level. Whereas the Weyl fermion case reduces in dimension, resembling a theory in quantum mechanics, the Dirac fermion case takes on a manifestly Lorentz covariant form. To achieve a classical kinetic theory for the non-Abelian Dirac fermion Berry phase a spinor construction of Barut and Zanghi is utilized. The axial anomaly is also studied at a quantum level. It is found that under an adiabatic approximation, which is necessary for facilitating a classical kinetic theory, the index of the Dirac operator for massless fermions vanishes. Even so, similarities of an axial rotation to an exact noncovariant Berry phase transform are drawn by application of the Fujikawa method to the Barut and Zanghi spinors on the worldline.

A derivation of fully polarization-resolved probabilities is provided for high-energy photon emission and electron-positron pair production in ultrastrong laser fields. The probabilities resolved in both electron spin and photon polarization of incoming and outgoing particles are indispensable for developing QED Monte Carlo and QED-particle-in-cell codes, aimed at the investigation of polarization effects in nonlinear QED processes in ultraintense laser-plasma and laser-electron beam interactions, and other nonlinear QED processes in external ultrastrong fields, which involve multiple elementary processes of a photon emission and pair production. The quantum operator method introduced by Baier and Katkov is employed for the calculation of probabilities within the quasiclassical approach and the local constant field approximation. The probabilities for the ultrarelativistic regime are given in a compact form and are suitable to describe polarization effects in strong laser fields of arbitrary configuration, rendering them very well suited for applications.

The minimal $U(1{)}_X$ extension of the Standard Model (SM) is a well-motivated new physics scenario, where anomaly cancellation dictates new neutral gauge boson ($Z^{\prime }$) couplings with the SM fermions in terms of the $U(1{)}_X$ charges of the new scalar fields. We investigate the SM charged fermion pair-production process for different values of these $U(1{)}_X$ charges at future $e^{-}{e}^{+}$ colliders: $e^{+}{e}^{-}\to f\overline{f}$. Apart from the standard $\gamma$ and $Z$-mediated processes, this model features additional $s$-channel (or both $s$ and $t$-channel when $f=e^{-}$) $Z^{\prime }$ exchange which interferes with the SM processes. We first estimate the bounds on the $U(1{)}_X$ coupling $(g^{\prime })$ and the $Z^{\prime }$ mass $(M_{Z^{\prime }})$ considering the latest dilepton and dijet constraints from the heavy resonance searches at the LHC. Then using the allowed values of $g^{\prime }$, we study the angular distributions, forward-backward $({\mathcal{A}}_{\mathrm{FB}})$, left-right $({\mathcal{A}}_{\mathrm{LR}})$, and left-right forward-backward $({\mathcal{A}}_{\mathrm{LR},\mathrm{FB}})$ asymmetries of the $f\overline{f}$ final states. We find that these observables can show substantial deviations from the SM results in the $U(1{)}_X$ model, thus providing a powerful probe of the multi-TeV $Z^{\prime }$ bosons at future $e^{+}{e}^{-}$ colliders.

We investigate the prospects for detecting axionlike particles (dubbed as “a”) via the decay $Z\to af\overline{f}$ at future $Z$ factories. Considering the decay channels $a\to {\mu }^{+}{\mu }^{-}$ and $a\to b\overline{b}$, four types of signals ${\mu }^{+}{\mu }^{-}\cancel{E}$, $bb\cancel{E}$, $e^{+}{e}^{-}{\mu }^{+}{\mu }^{-}$, and $e^{+}{e}^{-}bb$ are explored. We demonstrate that these channels are promising for detecting axionlike particles at $Z$ factories and obtain the sensitivity bounds on the couplings $g_{aZZ}$ and $g_{a\gamma Z}$.

We derive the on-shell form of amplitudes containing two external currents with a single hadron in the initial state and two hadrons in the final state, denoted as $1+\mathcal{J}\to 2+\mathcal{J}$. This class of amplitude is relevant in precision tests of the Standard Model as well as for exploring the structure of excited states in the QCD spectrum. We present a model-independent description of the amplitudes where we sum to all orders in the strong interaction. From this analytic form we are able to extract transition and elastic resonance form factors consistent with previous work as well as a novel Compton-like amplitude coupling a single particle state to a resonance. The results also hold for reactions where the one-particle state is replaced with the vacuum, namely $\mathcal{J}\to 2+\mathcal{J}$ amplitudes. We also investigate constraints placed upon the formalism for the case of a conserved vector current in the form of the Ward-Takahashi identity. The formalism presented here is valid for currents of arbitrary Lorentz structure and quantum numbers with spinless hadrons where any number of two-particle intermediate channels may be open. When combined with the appropriate finite-volume framework, this work facilitates the extraction of physical observables from this class of amplitudes via lattice QCD calculations.

In this note, we use local duality finite energy sum rule to test the validity of the Laplace sum rules results truncated at the dimension-six condensates for the estimates of the masses and couplings of the $Z_c$-like ground states in Albuquerque et al. [Phys. Rev. D 103, 074015 (2021)] by taking the example of the $D^{*}D$ molecule configuration. We confirm the existence of an eventual $(D^{*}D{)}_1$ radial excitation with a mass around 5700 MeV and coupling of 197(25) keV to the current which may mask the eventual $Z_c(4430)$ radial excitation candidate [named $(D^{*}D{)}_0$ in Albuquerque et al.] having a relatively small coupling $f_{(D^{*}D{)}_0}=46(56)\mathrm{keV}$. We add more explanations on the estimates in Albuquerque et al. from Laplace sum rules and comment on the results in Wang [arXiv:2202.06058; Commun. Theor. Phys. 63, 325 (2015)].

We study the color-spin interaction energy of a quark, a diquark and a baryon with their surrounding baryons and/or quark matter. This is accomplished by classifying all possible flavor and spin states of the resulting multiquark configuration in both the flavor SU(2) and SU(3) symmetric cases. We find that while the baryon has the lowest interaction energy when there is only a single surrounding baryon, the quark has the lowest interaction energy when the surrounding has more than three baryons or becomes a quark gas. As the short range nucleon-nucleon interactions are dominated by the color-spin interactions, our finding suggests that the baryon modes near other baryons are suppressed due to larger repulsive energy compared to that of a quark and thus provides a quark model basis for the quarkyoniclike phase in dense matter. At the same time, when the internal interactions are taken into account, and the matter density is high so that the color-spin interaction becomes the dominant interaction, the diquark becomes the lowest energy configuration and will thus appear in both the dense baryonic and/or quark matter.

In this work, we first introduced a generalized Wilson line gauge link that reproduces both staple and near straight links along a light cone in different parameter limits. We then studied the gauge-invariant bilocal orbital angular momentum operator with such a general gauge link. At the appropriate combination of limits, the operator reproduces both Jaffe-Manohar’s and Ji’s operator structures and offers a continuous analytical interpolation between the two.

A new approach to nonperturbative QCD, holographic light-front QCD, provides a comprehensive model for hadron dynamics and spectroscopy, incorporating color confinement, a universal hadron mass scale, the prediction of a massless pion in the chiral limit, and connections between the spectroscopy of mesons, baryons and tetraquarks across the full hadron spectrum. In this article we present predictions for the Sivers asymmetry and related transverse momentum distributions for the proton based on the light-front wavefunctions of the baryon eigenstate predicted by holographic QCD.

We find that the chiral phase transition (chiral crossover) in QCD at a physical point is triggered by a big imbalance among three fundamental quantities essential for the QCD vacuum structure; susceptibility functions for the chiral symmetry, axial symmetry, and the topological charge. The balance, dobbed the QCD trilemma, is unavoidably violated when one of the magnitudes among them is highly dominated, or suppressed. Based on a three-flavor Nambu-Jona-Lasinio model, we explicitly evaluate the amount of violation of the QCD trilemma at a physical point, and show that the violation takes place not only at vacuum, but even in a whole temperature regime including the chiral-crossover epoch. This work confirms and extends the suggestion recently reported from lattice QCD with two flavors on the dominance of the axial and topological susceptibilities left in the chiral susceptibility at high temperatures. It turns out that the imbalance is essentially due to the flavor symmetry violation of the lightest three flavors, and the flavor breaking specifically brings enhancement of the axial anomaly contribution in the chiral-order parameter, while the strength of the axial breaking and the transition rate of the topological charge are fairly insensitive to the flavor symmetry. The violation of the QCD trilemma and its flavor dependence can be tested by lattice simulations with $2+1$ flavors in the future, and would also give a new guiding principle to explore the flavor dependence of the chiral phase transition, such as the Columbia plot, including a possible extension with external fields.

The magnetic moments of the vector hidden-charmed tetraquark states that have been observed, and can be expected to be observed experimentally, have been determined using the light-cone sum rules taking into account the diquark-antidiquark structure with the quantum numbers $J^{PC}=1^{--}$ and $J^{PC}=1^{-+}$. Since these states are considered to have different flavors of light quarks, they have nonzero magnetic moments. The results obtained in this study can be checked for consistency by various methods. The magnetic moments of hadrons encompass useful knowledge about the distribution of charge and magnetization inside hadrons, which helps us to understand their geometrical shapes.

For current and future neutrino oscillation experiments using large liquid argon time projection chambers (LAr-TPCs), a key challenge is identifying neutrino interactions from the pervading cosmic-ray background. Rejection of such background is often possible using traditional cut-based selections, but this typically requires the prior use of computationally expensive reconstruction algorithms. This work demonstrates an alternative approach of using a 3D submanifold sparse convolutional network trained on low-level information from the scintillation light signal of interactions inside LAr-TPCs. This technique is applied to example simulations from ICARUS, the far detector of the short baseline neutrino program at Fermilab. The results of the network, show that cosmic background is reduced by up to 76.3% whilst neutrino interaction selection efficiency remains over 98.9%. We further present a way to mitigate potential biases from imperfect input simulations by applying domain adversarial neural networks (DANNs), for which modified simulated samples are introduced to imitate real data and a small portion of them are used for adversarial training. A series of mock-data studies are performed and demonstrate the effectiveness of using DANNs to mitigate biases, showing neutrino interaction selection efficiency performances significantly better than that achieved without the adversarial training.

We perform a manifestly covariant quantization of a Weyl-invariant (i.e., a locally scale-invariant) scalar-tensor gravity in the extended de Donder gauge condition (or harmonic gauge condition) for general coordinate invariance and a new scalar gauge for Weyl invariance within the framework of the BRST formalism. We show that choral symmetry, which is a Poincaré-like $IOSp(8|8)$ supersymmetry in the case of Einstein gravity, is extended to a Poincaré-like $IOSp(10|10)$ supersymmetry. We point out that there is a gravitational conformal symmetry in quantum gravity and account for how conventional conformal symmetry in a flat Minkowski space-time is related to the gravitational conformal symmetry. Moreover, we examine the mechanism of the spontaneous symmetry breaking of the choral symmetry, and show that the gravitational conformal symmetry is spontaneously broken to the Poincaré symmetry and the corresponding massless Nambu-Goldstone bosons are the graviton and the dilaton. We also prove the unitarity of the physical $S$ matrix on the basis of the BRST quartet mechanism.

We study the Neveu-Schwarz-Ramond (NSR) open superstring theory in the proper-time gauge. The string field action is obtained by evaluating the Polyakov string path integral. In this study, we focus on the open-string free-field action, which corresponds to the string path integral on a strip. Depending on the periodicity of the fermion fields, the open superstring has two sectors: The Neveu-Schwarz (NS) and Ramond (R) sectors. We can impose the gauge conditions to fix the (super) reparametrization invariance on the two-dimensional metric and its superpartner on the string world sheet to secure the covariance, in contrast to the light cone gauge condition. Accordingly, the proper-time emerges in the NS sector and both proper-time and its superpartner appear in the R-sector. Integration leads to free-string field actions in both sectors.

We write the curvature of spacetime in terms of the excitation probability of particle detectors ultrarapidly coupled to a quantum field. More precisely, we provide an expansion for the excitation probability of a smeared Unruh-DeWitt detector delta-coupled to a real scalar quantum field in a curved background. Using a short-distance expansion for the Wightman function, we express the excitation probability of a detector as the transition probability in Minkowski spacetime plus correction terms written as a function of the curvature tensors and the detector size. Comparing the excitation probability in curved spacetimes with its flat analog, we are able to express the components of the Ricci and Riemann curvature tensors as a function of physically measurable excitation probabilities of different-shaped detectors.

The standard description of particles and fundamental interactions is crucially based on a regular metric background. In the language of differential geometry, this dependence is encoded into the action via Hodge star dualization. As a result, the conventional forms of the scalar and Yang-Mills actions break down in a pregeometric regime where the metric is degenerate. This suggests the use of first order formalism, where the metric may emerge from more fundamental constituents and the theory can be consistently extended to the pregeometric phase. We systematically explore different realizations and interpretations of first order formalism, finding that a fundamental vector or spinor substructure brings about continuum magnetization and polarization as integration constants. This effect is analogous to the description of the cosmological dark sector in a recent self-dual formulation of gravity, and the similar form obtained for the first order Yang-Mills theory suggests new paths toward unification.

The dynamics of charged particles moving around a Kerr-Newman black hole surrounded by cloud strings, quintessence and electromagnetic field is integrable due to the presence of a fourth constant of motion like the Carter constant. The fourth motion constant and the axial symmetry of the spacetime give a chance to the existence of radial effective potentials with stable circular orbits in two-dimensional planes, such as the equatorial plane and other nonequatorial planes. They also give a possibility of the presence of radial effective potentials with stable spherical orbits in the three-dimensional space. The dynamical parameters play important roles in changing the graphs of the effective potentials. In addition, variations of these parameters affect the presence or absence of stable circular orbits, innermost stable circular orbits, stable spherical orbits, and marginally stable spherical orbits. They also affect the radii of the stable circular or spherical orbits. It is numerically shown that the stable circular orbits and innermost stable circular orbits can exist not only in the equatorial plane but also in the nonequatorial planes. Several stable spherical orbits and marginally stable spherical orbits are numerically confirmed too. In particular, there are some stable spherical orbits and marginally stable spherical orbits with vanishing angular momenta which cover the whole range of latitudinal coordinates.