Consider a set of multivariate distributions, $F_1,\dots ,F_M$, aiming to explain the same phenomenon. For instance, each $F_m$ may correspond to a different candidate background model for calibration data, or to one of many possible signal models we aim to validate on experimental data. In this article, we show that tests for a wide class of apparently different models $F_m$ can be mapped into a single test for a reference distribution $Q$. As a result, valid inference for each $F_m$ can be obtained by simulating only the distribution of the test statistic under $Q$. Furthermore, $Q$ can be chosen conveniently simple to substantially reduce the computational time.

We derive spectral line shapes of the expected signal for a haloscope experiment searching for axionlike dark matter. The knowledge of these line shapes is needed to optimize an experimental design and data analysis procedure. We extend the previously known results for the axion-photon and axion-gluon couplings to the case of gradient (axion-fermion) coupling. A unique feature of the gradient interaction is its dependence not only on magnitudes but also on directions of velocities of galactic halo particles, which leads to the directional sensitivity of the corresponding haloscope. We also discuss the daily and annual modulations of the gradient signal caused by the Earth’s rotational and orbital motions. In the case of detection, these periodic modulations will be an important confirmation that the signal is sourced by axionlike particles in the halo of our Galaxy.

We present a calculation of the net baryon number density as a function of imaginary baryon number chemical potential, obtained with highly improved staggered quarks at temporal lattice extent of $N_{\tau }=4$, 6. We construct various rational function approximations of the lattice data and discuss how poles in the complex plane can be determined from them. We compare our results of the singularities in the chemical potential plane to the theoretically expected positions of the Lee-Yang edge singularity in the vicinity of the Roberge-Weiss and chiral phase transitions. We find a temperature scaling that is in accordance with the expected power law behavior.

We investigate the finite-temperature and -density chiral Gross-Neveu model with an axial $U_A(1)$ symmetry in $1+1$ dimensions on the lattice. In the limit where the number of flavors $N_{\mathrm{f}}$ tends to infinity the continuum model has been solved analytically and shows two phases: a symmetric high-temperature phase with a vanishing condensate and a low-temperature phase in which the complex condensate forms a chiral spiral which breaks translation invariance. In the lattice simulations we employ chiral SLAC fermions with exact axial symmetry. Similarly to $N_{\mathrm{f}}\to \infty$, we find for eight flavors, where quantum and thermal fluctuations are suppressed, two distinct regimes in the $(T,\mu )$ phase diagram, characterized by qualitatively different behavior of the two-point functions of the condensate fields. More surprisingly, at $N_{\mathrm{f}}=2$, where fluctuations are no longer suppressed, the model still behaves similarly to the $N_{\mathrm{f}}\to \infty$ model and we conclude that the chiral spiral leaves its footprints even on systems with a small number of flavors. For example, at low temperature the two-point functions are still dominated by chiral spirals with pitches proportional to the inverse chemical potential, although in contrast to large $N_{\mathrm{f}}$ their amplitudes decrease with distance. We argue that these results should not be interpreted as the spontaneous breaking of a continuous symmetry, which is forbidden in two dimensions. Finally, using Dyson-Schwinger equations we calculate the decay of the $U_A(1)$-invariant fermion four-point function in search for a BKT phase at zero temperature.

We make a systematic study of $\mathrm{\Lambda }$ hyperon polarizations in unpolarized lepton induced semi-inclusive reactions such as $e^{-}N\to e^{-}\mathrm{\Lambda }X$ and $e^{+}{e}^{-}\to \mathrm{\Lambda }hX$. We present the general form of cross sections in terms of structure functions obtained from a general kinematic analysis. This already shows that the produced hyperons can be polarized in three orthogonal directions, i.e., the longitudinal direction along the hyperon momentum, the normal direction of the production plane, and the transverse direction in the production plane. We present the parton model results at the leading twist and leading order in perturbative QCD using transverse momentum dependent factorization and provide the expressions for these structure functions and polarizations in terms of three-dimensional parton distribution functions and fragmentation functions. We emphasize in particular that by studying the longitudinal polarization and the transverse polarization in the production plane, we can extract the corresponding chiral-odd fragmentation functions $H_{1Lq}^{\perp \mathrm{\Lambda }}$, $H_{1Tq}^{\mathrm{\Lambda }}$, and $H_{1Tq}^{\perp \mathrm{\Lambda }}$. We also present numerical results of rough estimates utilizing available parametrizations of fragmentation functions and approximations. We discuss how to measure these polarizations and point out in particular that they can be carried out in future EIC and/or $e^{+}{e}^{-}$ annihilation experiments such as Belle.

In the framework of an extended chromomagnetic model, we systematically study the mass spectrum of the $S$-wave $qQ\overline{Q}\overline{Q}$ tetraquarks. Their mass spectra are mainly determined by the color interaction. For the $qc\overline{c}\overline{c}$, $qb\overline{c}\overline{c}$, and $qb\overline{b}\overline{b}$ tetraquarks, the color interaction favors the color-sextet $|(qQ{)}^{6_c}(\overline{Q}\overline{Q}{)}^{{\overline{6}}_c}⟩$ configuration over the color-triplet $|(qQ{)}^{{\overline{3}}_c}(\overline{Q}\overline{Q}{)}^{3_c}⟩$ one. But for the $qc\overline{b}\overline{b}$ tetraquarks, the color-triplet configuration is favored. We find no stable states which lie below the thresholds of two pseudoscalar mesons. The lowest axial-vector states with the $qQ\overline{b}\overline{b}$ flavor configuration may be narrow. They lie just above the thresholds of two pseudoscalar mesons, but cannot decay into these channels because of the conservation of the angular momentum and parity.

We present a calculation of the full set of next-to-next-to-leading-order QED corrections to unpolarized Møller scattering. This encompasses photonic, leptonic, and nonperturbative hadronic corrections and includes electron mass effects as well as hard photon radiation. The corresponding matrix elements are implemented in the Monte Carlo framework mcmule allowing for the computation of fully differential observables. As a first application we show results tailored to the kinematics and detector design of the PRad II experiment where a high-precision theory prediction for Møller scattering is required to achieve the targeted precision. We observe that the corrections become essential to reliably calculate the corresponding differential distributions especially in regions where the leading-order contribution is absent.

Experimental data have provided intriguing hints for the violation of lepton flavor universality (LFU), including $B\to D^{(*)}\tau \nu /B\to D^{(*)}\ell \nu$, the anomalous magnetic moment of the muon and $b\to s{\ell }^{+}{\ell }^{-}$ with a significance of $>3\sigma$, $>4\sigma$, and $>5\sigma$, respectively. Furthermore, in a recent reanalysis of 2018 Belle data, it was found that the forward-backward asymmetry ($\mathrm{\Delta }{A}_{\mathrm{FB}}$) of $B\to D^{*}\mu \overline{\nu }$ vs $B\to D^{*}e\overline{\nu }$ disagrees with the SM prediction by $\approx 4\sigma$, providing an additional sign of LFU violation. We show that a tensor operator is necessary to significantly improve the agreement with data in $\mathrm{\Delta }{A}_{\mathrm{FB}}$ while respecting the bounds from other $b\to c\ell \nu$ observables. Importantly, this tensor operator can only be induced (at tree-level within renormalizable models) by a scalar leptoquark. Furthermore, among the two possible representations, the $SU(2{)}_L$-singlet $S_1$ and the doublet $S_2$, which can interestingly both also account for the anomalous magnetic moment of the muon, only $S_1$ can provide a good fit. Even though the constraints from (differences of) other angular observables prefer a smaller value of $\mathrm{\Delta }{A}_{\mathrm{FB}}$ than the current central one, this scenario is significantly preferred (nearly $4\sigma$) over the Standard Model hypothesis, and is compatible with constraints such as $B\to K^{*}\nu \nu$ and electroweak precision bounds. Therefore, if the $\mathrm{\Delta }{A}_{\mathrm{FB}}$ anomaly is confirmed, it would provide circumstantial evidence for scalar leptoquarks and pave the way for a natural connection with all other anomalies pointing toward LFU violation.

Based on $\eta \text{−}{\eta }^{\prime }$ mixing analysis, we propose a novel method to extract the physical solutions for the hadronic properties of the $Y(4230)$ resonance from the experimental data. Experimentally, multiple solutions have been reported in the decays of $Y(4230)\to \eta J/\psi$ and $Y(4230)\to {\eta }^{\prime }J/\psi$. Utilizing our method, we determine a unique solution for the process $Y(4230)\to {\eta }^{\prime }J/\psi$. Likewise, two solutions for the process $Y(4230)\to \eta J/\psi$ are preferred among the originally reported three solutions under the assumption that $Y(4230)$ does not take an $s\overline{s}$ component.

Freudenthal duality (F-duality), an anti-involution of charge vectors, keeps the entropy and attractor solutions invariant for an extremal supersymmetric black hole. We analyze the effect of F-duality on the entropy of a near-extremal STU black hole in $\mathcal{N}=2$ ungauged, four-dimensional supergravity. We consider double-extremal black holes, whose attractor solutions are fixed in terms of the black hole charges throughout the moduli space. It is well known that Jackiw-Teitelboim (JT) gravity governs the dynamics of the near-horizon regions of higher-dimensional, near-extremal black holes. Owing to this fact, we reduce the four-dimensional supergravity theory to two dimensions to construct a JT gravity–like model and compute the near-extremal entropy. We then analyze the effect of F-duality on this entropy. We show that the F-duality breaks down for the case of near-extremal solutions if one considers the duality operation generated through near-extremal entropy rather than the extremal one.

We study quantum dissipative effects due to the nonrelativistic, bounded, accelerated motion of a single neutral atom in the presence of a planar perfect mirror, i.e., a perfect conductor at all frequencies. We consider a simplified model whereby a moving “scalar atom” is coupled to a quantum real scalar field, subjected to either Dirichlet or Neumann boundary conditions on the plane. We use an expansion in powers of the departure of the atom with respect to a static average position to compute the vacuum persistence amplitude and the resulting vacuum decay probability. We evaluate transition amplitudes corresponding to the excitation of the atom plus the emission of a particle, and show explicitly that the vacuum decay probabilities match the results obtained by integrating the transition amplitudes over the directions of the emitted particle. We also compute the spontaneous emission rate of an oscillating atom that is initially in an excited state.

We consider finite and infinite-dimensional ghost-ridden dynamical systems whose Hamiltonians involve nonpositive definite kinetic terms. We point out the existence of three classes of such systems where the ghosts are benign, i.e., systems whose evolution is unlimited in time: (i) systems obtained from the variation of bounded-motion systems; (ii) systems describing motions over certain Lorentzian manifolds and (iii) higher-derivative models related to certain modified Korteweg-de Vries equations.

We study a spherical black hole formed slowly in a heat bath in the context of ordinary field theory, which we expect to have the typical properties of black holes. We assume that the matter field is conformal and that the metric satisfies the semi-classical Einstein equation $G_{\mu \nu }=8\pi G⟨\psi |T_{\mu \nu }|\psi ⟩$, where $|\psi ⟩$ is the wave function of the matter field. Then, as a necessary condition, its trace part must be satisfied, ${G^{\mu }}_{\mu }=8\pi G⟨\psi |{T^{\mu }}_{\mu }|\psi ⟩$, whose right-hand side is independent of $|\psi ⟩$ and is determined only by the metric through the four-dimensional Weyl anomaly. With some physically reasonable assumptions, this equation restricts the interior metric to a certain class. Such metrics are approximately warped products of ${\mathrm{AdS}}_2$ and $S^2$ with almost Planckian curvature. Among them, we find one that is consistent with Hawking radiation and is smoothly connected to the exterior Schwarzschild metric slightly outside the Schwarzschild radius. This leads to a picture that the black hole is a dense object with a surface (not a horizon), which evaporates due to Hawking-like radiation when taken out of the bath. Other solutions represent objects that are larger in size than a black hole, which may be useful for analyzing ultradense stars.

We study Proca stars in a vector-tensor gravity model inspired by Horndeski’s generalized Einstein-Maxwell field equations, supplemented with a mass term for the vector field. We discuss the effects of the nonminimal coupling term on the properties of the resulting Proca stars. We show that the sign of the coupling constant is crucial in determining the generic properties of these generalized Proca star solutions, as soon as the magnitude of the coupling constant is sufficiently large to allow for significant deviations from the standard Proca star case. For negative coupling constant we observe a new type of limiting behavior for the generalized Proca stars, where the spacetime splits into an interior region with matter fields and an exterior Schwarzschild region.

We study a family of solutions of Einstein-nonlinear sigma models with $S^2$ and $SU(2)\sim S^3$ target manifolds. In the $S^2$ case, the solutions are smooth everywhere, are free of conical singularities, and approach asymptotically the metric of a cosmic string, with a mass per length that is proportional to the absolute value of the winding number from topological spheres onto the target $S^2$. This gives an interesting example of a relation between a mass and a topological charge. The case with target $SU(2)$ generalizes the stationary solution found in Canfora et al.Eur. Phys. J. C 81, 55 (2021) to parallel waves with a nonplanar wave front $\mathcal{W}$. We prove that these $\mathcal{W}$-fronted parallel waves are subquadratic in the classification in Flores et al.Classical Quantum Gravity 20, 2275 (2003) and thus are causally well behaved. These spacetimes have a nonvanishing baryon current and their geometry has many striking features.

With the help of the tachyonic trapping mechanism one can potentially solve a number of problems affecting quintessential inflation models. In this mechanism we introduce a trapping field with a spontaneous symmetry breaking potential. When the quintessential inflaton passes the critical point, a sudden burst of particle production is able to reheat the Universe and trap the inflaton away from the minimum of its potential. However, self-interactions of the trapping field suppress particle production and reduce the efficiency of this process. We develop a method to compute the magnitude of the suppression and explore the parameter space in which the mechanism can be applied effectively.

Our Universe is expected to finally approach a de Sitter universe whose horizon is considered to be in thermal equilibrium. In the present article, both the energy stored on the horizon and its thermodynamic fluctuations are examined through the holographic equipartition law. First, it is confirmed that a flat Friedmann-Robertson-Walker universe approaches a de Sitter universe, using a cosmological model close to lambda cold dark matter models. Then, based on the holographic equipartition law, the energy density of the Hubble volume is calculated from the energy on the Hubble horizon of a de Sitter universe. The energy density for a de Sitter universe is constant and the order of the energy density is consistent with the order of that for the observed cosmological constant. Second, thermodynamic fluctuations of energy on the horizon are examined, assuming stable fluctuations around thermal equilibrium states. A standard formulation of the fluctuations for a canonical ensemble is applied to the Hubble horizon of a de Sitter universe. The thermodynamic fluctuations of the energy are found to be a universal constant corresponding to the Planck energy, regardless of the Hubble parameter. In contrast, the relative fluctuations of the energy can be characterized by the ratio of the one-degree-of-freedom energy to the Planck energy. At the present time, the order of the relative fluctuations should be within the range of a discrepancy derived from a discussion of the cosmological constant problem, namely, a range approximately from ${10}^{-60}$ to ${10}^{-123}$. The present results may imply that the energy stored on the Hubble horizon is related to a kind of effective dark energy, whereas the energy that can be “maximally” stored on the horizon may behave as if it were a kind of effective vacuum-like energy in an extended holographic equipartition law.

We find that the adiabatic fluctuations produced in the primordial plasma by cosmological inflation resonantly excite the axion field during the QCD phase transition by pumping axions from low momentum modes to modes with momentum up to of order $\sqrt{3}m$ where $m$ is the axion mass. We derive the momentum distribution of the excited axions. The fraction of cold axions that get excited is of order one if the axion mass is larger than a few $\mu \mathrm{eV}$. The effect occurs whether inflation happens before or after the Peccei-Quinn phase transition.

The comoving sound horizon at the baryon drag epoch, $r_d$, encapsulates very important physical information about the prerecombination era and serves as a cosmic standard ruler. On the other hand, the absolute magnitude of supernovae of type Ia (SNIa), $M$, is pivotal to infer the distances to these standard candles. Having access to (at least) one of these two quantities is crucial to measure the Hubble parameter $H_0$ from BAO/SNIa data. In this work we present a new method to measure how long is the cosmic ruler and how bright are the standard candles independently from the main drivers of the $H_0$ tension, namely by avoiding (i) the use of CMB data; (ii) the calibration of SNIa in the first steps of the cosmic distance ladder; and (iii) the assumption of any concrete cosmological model. We only assume that SNIa can be safely employed as standard candles and $r_d$ as a standard ruler, together with the validity of the cosmological principle and the metric description of gravity, with photons propagating in null geodesics and the conservation of the photon number. Our method is based on the minimization of a loss function that represents the level of inconsistency between the low-redshift datasets employed in this study, to wit: SNIa, BAO, and cosmic chronometers. In our main analysis we obtain: $r_d=({146.0}_{-5.1}^{+4.2})\mathrm{Mpc}$, $M=-19.362_{-0.067}^{+0.078}$. The former is fully compatible with Planck’s $\mathrm{\Lambda }\mathrm{CDM}$ best-fit cosmology, but still leaves plenty of room for new physics before the decoupling, whereas our constraint on $M$ lies closer to the value preferred by the concordance model, although it is only $\sim 1.4\sigma$ below the SH0ES measurement.

In the framework of the Brans-Dicke scalar-tensor theory of gravitation, we investigate the role of a self-interacting fermionic field in a universe filled with dust and radiation constituents. This model is shown to present a variety of behaviors, depending on the parameters chosen. In particular, we find that the fermionic field is capable of promoting a transition from an initially decelerated, radiation-dominated period to a later accelerated regime where the fermion prevails. The Brans-Dicke field is found to approach a constant value, and an intermediary matter-dominated era is observed. The dependence of the acceleration on the fermionic potential was also investigated. On a second analysis, the possibility of a direct energy exchange between the constituents was considered, using the dynamical pressure approach. On this later formulation a three-era cosmological regime emerged.