For a horizonless Schwarzschild star with a photon sphere, its strong deflection gravitational lensing can generate unique inner relativistic images of pointlike sources, which are absent for a Schwarzschild black hole. In order to understand the signatures of its outer and inner relativistic images, we generalize the strong deflection limit method for an ultracompact object by including the finite distance effect of a source, and analytically calculate the complex visibility of all the relativistic images of the Schwarzschild star. We show that the interferometric pattern of the relativistic images of the Schwarzschild star has richer features than the one of the Schwarzschild black hole and is more likely to be resolved by future space-borne very long baseline interferometry.

We present results from a $3.25\mathrm{kg}\text{−}\mathrm{day}$ target exposure of two silicon charge-coupled devices (CCDs), each with 24 megapixels and skipper readout, deployed in the DAMIC setup at SNOLAB. With a reduction in pixel readout noise of a factor of 10 relative to the previous detector, we investigate the excess population of low-energy events in the CCD bulk previously observed above expected backgrounds. We address the dominant systematic uncertainty of the previous analysis through a depth fiducialization designed to reject surface backgrounds on the CCDs. The measured bulk ionization spectrum confirms the presence of an excess population of low-energy events in the CCD target with characteristic rate of $\sim 7$ events per kg-day and electron-equivalent energies of $\sim 80\mathrm{eV}$, whose origin remains unknown.

Using the relativistic complex scalar field model with a repulsive self-interaction, we discuss the ground state structure of charged pion condensation under the coexistence of parallel rotation and magnetic field. Our previous study found that the density distribution profile of the condensates is a supergiant quantum vortex phase and change with rotational speed and coupling constant. In this work, we further discover vortex lattice structures in the condensates under conditions of small rotation and strong coupling constant. This mechanism can be thought of as electrical superconductivity: Vortex lattices are created to better adapt to changes in rotation and interaction. Furthermore, large rotation and weak coupling constant are more likely to cause the vortex lattices to be destroyed and form a giant quantum vortex similar to a doughnut. We expect this phenomenon can be observed in the relativistic noncentral heavy ion collisions with large rotation and strong magnetic field.

We newly develop a renormalization group (RG) improvement for thermally resummed effective potentials. In this method, $\beta$-functions are consistently defined in resummed perturbation theories, so that order-by-order RG invariance is not spoiled after thermal resummation. With this improvement, scale dependences of phase transition quantities such as a critical temperature, which are known to be notoriously large at the one-loop order, are greatly reduced compared to calculations with the conventional $\overline{\mathrm{MS}}$ scheme. By taking advantage of the RG invariance, we also devise a resummation method that can incorporate potentially harmful large logarithmic terms and temperature-dependent power corrections in a generic form. We point out that a resummed one-loop effective potential refined by the method can give results that agree with those obtained by resummed two-loop effective potentials within errors.

In an optically active medium, such as a plasma that contains a neutrino background, the left-handed and right-handed polarization photon modes acquire different dispersion relations. We study the propagation of photons in such a medium, which is otherwise isotropic, within the framework of the covariant collissionless Boltzmann equation incorporating a term that parametrizes the optical activity. Using the linear response approximation, we obtain the formulas for the components of the photon polarization tensor, expressed in terms of integrals over the momentum distribution function of the background particles. The main result here is the formula for the $P$- and $CP$-breaking component of the photon polarization tensor in terms of the parameter involved in the new term we consider in the Boltzmann equation to describe the effects of optical activity. We discuss the results for some particular cases, such as long-wavelength and nonrelativistic limits, for illustrative purposes. We also discuss the generalizations of the $P$- and $CP$-breaking term we included in the Boltzmann equation. In particular we consider the application to a plasma with a neutrino background and establish contact with calculations of the photon self-energy in those systems in the framework of thermal field theory.

Temporary matter domination and late entropy dilution, injected by a “long-lived” particle in the early Universe, serves as a standard mechanism for yielding the correct dark matter relic density. We recently pointed out the cosmological significance of diluting particle’s partial decay into dark matter. When repopulated in such a way, dark matter carries higher momentum than its thermal counterpart, resulting in a suppression of the linear matter power spectrum that is constrained by the large scale structure observations. In this work, we study the impact of such constraints on the minimal left-right symmetric model that accounts for the origin of neutrino mass. We map out a systematic anatomy of possible dilution scenarios with viable parameter spaces, allowed by cosmology and various astrophysical and terrestrial constraints. We show that to accommodate the observed dark matter relic abundance the spontaneous left-right symmetry breaking scale must be above PeV and cosmology will continue to provide the most sensitive probes of it. In case the dilutor is one of the heavier right-handed neutrinos, it can be much lighter and lie near the electroweak scale.

We study thermal production of dark matter (DM) in a realization of the minimal models of Bonnefoy et al. [Phys. Rev. Lett. 131, 221802 (2023)], where parity is used to solve the strong $CP$ problem by transforming the entire Standard Model (SM) into a mirror copy. Although the mirror electron $e^{\prime }$ is a good DM candidate, its viability is mired by the presence of the mirror up quark $u^{\prime }$, whose abundance is intimately related to the $e^{\prime }$ abundance and must be suppressed. This can be achieved through a sequential freeze-in mechanism, where mirror photons are first produced from SM gluons, and then the mirror photons produce $e^{\prime }$. After computing the details of this double freeze-in, we discuss the allowed parameter space of the model, which lies at the threshold of experimental observations. We find that this origin of $e^{\prime }$ DM requires a low reheating temperature after inflation and is consistent with the baryon asymmetry arising from leptogenesis, providing mirror neutrinos have a significant degeneracy. Finally, we show that this $e^{\prime }$ DM is not compatible with Higgs parity, the simplest scheme with exact parity, unless SM parameters deviate significantly from their central values or the minimal model is extended.

The significance of the electroweak phase transition is undeniable, and although initially it was believed that it was second order, it is now believed that it is a first-order transition. However, it is not a strong first-order phase transition in the context of the standard model, and the remedy to this issue is to use the Higgs portal and directly couple the Higgs to a hidden scalar sector. This can result in a strong electroweak phase transition, while the couplings to a hidden scalar are constrained by several phenomenological constraints, such as the sphaleron rate criterion and the branching ratio of the Higgs to invisible channels. In this work, we consider the standard singlet extensions of the standard model, including dimension-six non-renormalizable operators that couple a real singlet scalar field with the Higgs doublet. As a result, we examine the effects of those Higgs-singlet couplings on the electroweak phase transition. The effective theory, where the nonrenormalizable couplings originate from, is considered to be active beyond 15 TeV. As we show, the Universe experiences a two-step electroweak phase transition, a primary phase transition in the singlet sector at a high temperature, and then a subsequent first-order phase transition from the singlet vacuum to the electroweak vacuum. The singlet’s phase transition can either be second order or first order, depending on the singlet mass and its couplings to the Higgs. In particular, we show that the dimension-six operator assists in generating a strong electroweak phase transition in regions of the parameter space that were excluded in the previous singlet extensions of the standard model. This is further apparent for low singlet masses $m_S<m_H/2$, which are rarely taken into account in the literature due to the invisible branching ratio of the Higgs boson. In some limited cases in the parameter space, the electroweak phase transition is weakened by the presence of the higher order operator.

We study the effects of taste degeneracy on the continuum scaling of the localization properties of the staggered Dirac operator in high-temperature QCD using numerical simulations on the lattice, focusing in particular on the position of the mobility edge separating localized and delocalized modes at the low end of the spectrum. We find that, if the continuum limit is approached at fixed spatial volume, the restoration of taste symmetry leads to sizeable systematic effects on estimates for the mobility edge obtained from spectral statistics, which become larger and larger as the lattice spacing is decreased. Such systematics, however, are found to decrease if the volume is increased at fixed lattice spacing. We argue that spectral statistics estimate correctly the position of the mobility edge in the thermodynamic limit at fixed spacing, and support this with an independent numerical analysis based directly on the properties of the Dirac eigenvectors, that are unaffected by taste degeneracy. We then provide a theoretical argument justifying the exchange of the thermodynamic and continuum limits when studying localization. This allows us to use spectral statistics to determine the position of the mobility edge, and to obtain a controlled continuum extrapolation of the mobility edge for the first time.

In this work, we systematically study the electromagnetic properties including the M1 radiative decay widths and the magnetic moments of the isoscalar ${\mathrm{\Xi }}_{cc}{D}^{(*)}$, ${\mathrm{\Xi }}_{cc}{D}_1$, and ${\mathrm{\Xi }}_{cc}{D}_2^{*}$ triple-charm molecular-type pentaquark candidates, where we adopt the constituent quark model and consider both the $S-D$ wave mixing effect and the coupled channel effect. Our numerical results suggest that the M1 radiative decay widths and the magnetic moments of the isoscalar ${\mathrm{\Xi }}_{cc}{D}^{(*)}$, ${\mathrm{\Xi }}_{cc}{D}_1$, and ${\mathrm{\Xi }}_{cc}{D}_2^{*}$ triple-charm molecular-type pentaquark candidates can reflect their inner structures, and the study of the electromagnetic properties is an important step to construct the family of the triple-charm molecular-type pentaquarks. With the accumulation of the experimental data during the high-luminosity phase of LHC, we expect that the present work combined with the corresponding mass spectrum information can encourage the experimental colleagues at LHCb to focus on the isoscalar ${\mathrm{\Xi }}_{cc}{D}^{(*)}$, ${\mathrm{\Xi }}_{cc}{D}_1$, and ${\mathrm{\Xi }}_{cc}{D}_2^{*}$ triple-charm molecular-type pentaquark candidates.

Based on the method of solving the complete Salpeter equation, we study the semileptonic decays of a $0^{-}$ heavy meson to $1P$, $2P$, or $3P$ heavy-tensor mesons, $B_q\to (\overline{c}q)(nP){\ell }^{+}{\nu }_{\ell }$ $(q=u,d,s,c;n=1,2,3)$. The obtained branching ratio of $\mathcal{B}(B\to D_2^{\star }(2460){\ell }^{+}{\nu }_{\ell })$ agrees with the experimental data. We predict $\mathcal{B}(B_s^0\to D_{s2}^{\star -}(1P){\ell }^{+}{\nu }_{\ell })=3.76\times {10}^{-3}$ and $\mathcal{B}(B_c^{+}\to {\chi }_{c2}(1P){\ell }^{+}{\nu }_{\ell })=1.82\times {10}^{-3}$. The branching ratios of decays to $2P$ and $3P$ final states are found to be very small. The ratios $\mathcal{R}({\overline{D}}_2^{\star 0})=0.045$, $\mathcal{R}(D_{s2}^{\star })=0.048$ and $\mathcal{R}({\chi }_{c2})=0.059$ are also obtained. This study focuses on the contribution of relativistic corrections. The wave function of the pseudoscalar includes nonrelativistic $S$-wave and relativistic $P$-wave. While for a tensor, it contains nonrelativistic $P$-wave and relativistic $P$-, $D$-, and $F$-waves in its wave function. We find the individual contributions of relativistic partial waves are significant in the decay $B\to D_2^{\star }(2460){\ell }^{+}{\nu }_{\ell }$, but the overall contribution of the relativistic effect is 24.4%, which is small due to cancellation. Similarly, for the decay $B_s^0\to D_{s2}^{\star -}(1P){\ell }^{+}{\nu }_{\ell }$, the contribution of the relativistic effect is 28.8%. While for $B_c^{+}\to {\chi }_{c2}(1P){\ell }^{+}{\nu }_{\ell }$, the individual contributions of relativistic partial waves and the overall relativistic correction are both small, the later of which is 22.1%.

We show that the stress tensor of a real scalar quantum field on Reissner-Nordström-de Sitter spacetime exhibits correlations over macroscopic distances near the Cauchy horizon. These diverge as the Cauchy horizon is approached and are universal, i.e., state independent. This signals a breakdown of the semiclassical approximation near the Cauchy horizon. We also investigate the effect of turning on a charge of the scalar field and consider the correlation of the stress tensor between the two poles of the Cauchy horizon of Kerr-de Sitter spacetime.

Based on lattice QCD results of equation of state and baryon number susceptibility at zero baryon chemical potential, and supplemented by machine learning techniques, we construct the analytic form of the holographic black hole metric in the Einstein-Maxwell-Dilaton framework for pure gluon, 2-flavor, and ($2+1$)-flavor systems, respectively. The dilaton potentials solved from Einstein equations are in good agreement with the extended nonconformal DeWolfe-Gubser-Rosen type dilaton potentials fixed by lattice QCD equation of state, which indicates the robustness of the Einstein-Maxwell-Dilaton framework. The predicted critical end point in the ($2+1$)-flavor system is located at ($T^c=0.094\mathrm{GeV}$, ${\mu }_B^c=0.74\mathrm{GeV}$), which is close to the results from the realistic Polyakov-Nambu-Jona-Lasinio model, the functional renormalization group, and the holographic model with extended DeWolfe-Gubser-Rosen dilaton potential.

Moduli stabilization is key to obtaining phenomenologically viable string models. Nongeometric compactifications, like $T$-duality orbifolds ($T$ folds), are capable of freezing many moduli. However, in this paper we emphasize that $T$ folds, admitting free fermionic descriptions, can be associated with a large number of different $T$ folds with varying number of moduli, since the fermion pairings for bosonization are far from unique. Consequently, in one description a fermionic construction might appear to be asymmetric, and hence nongeometric, while in another it admits a symmetric orbifold description. We introduce the notion of intrinsically asymmetric $T$ folds for fermionic constructions that do not admit any symmetric orbifold description after bosonization. Finally, we argue that fermion symmetries induce mappings in the bosonized description that extend the $T$-duality group.

We define generalized Gaussian states for quantum cosmological models based on the $\mathfrak{su}(\mathfrak{1},\mathfrak{1})$ algebra, with particular emphasis on its realization in group field theory for a single field mode, and study their semiclassical properties. These states are generalizations of coherent, squeezed, and thermal states considered previously. As two possible characterizations of semiclassicality, we contrast the requirement of small relative fluctuations in volume and energy with the saturation of the Robertson-Schrödinger uncertainty principle. We find that for the most general class of states, the appearance of small relative fluctuations, which we take as the main criterion relevant for the emergence of cosmology, is mostly determined by the amount of displacement used to define the state. We also observe that defining such generalized Gaussian states is less straightforward in the algebraic approach to canonical quantization of group field theory, and discuss special cases.

We consider ($1+1$)-dimensional dilatonic black hole with two horizons, canonical temperatures of which do not coincide. We show that the presence of quantum fields in such a background leads to a substantial backreaction on the metric: 2D dilatonic analog of the semiclassical Einstein equations are solved self-consistently, and we demonstrate that taking into account backreaction leads to a geometry with two horizons with coinciding temperatures.

We prove that, as opposed to the familiar charged Reissner-Nordström black-hole spacetime, the spatially regular charged Ayón-Beato-García (ABG) black-hole spacetime can support charged scalar clouds, spatially regular stationary matter configurations which are made of linearized charged massive scalar fields. Interestingly, we reveal the fact that the composed black-hole-field system is amenable to an analytical treatment in the regime $Q/M\ll 1\ll M\mu$ of weakly charged black holes and large-mass fields, in which case it is proved that the dimensionless physical parameter $\alpha \equiv \frac{qQ}{M\mu }$ must lie in the narrow interval $\alpha \in (\sqrt{\frac{3240}{6859}},\frac{16}{23})$ [here $\{M,Q\}$ are the mass and electric charge of the central black hole and $\{\mu ,q\}$ are the proper mass and charge coupling constant of the supported scalar field]. In particular, we explicitly prove that, for weakly charged black holes, the discrete resonance spectrum $\{\alpha (M,Q,\mu ,q;n){\}}_{n=0}^{n=\infty }$ of the composed charged-ABG-black-hole-charged-massive-scalar-field cloudy configurations can be determined analytically in the eikonal large-mass regime.

We investigate the gravitational Aharonov-Bohm effect by placing a quantum system in free fall around a gravitating body, e.g., a satellite orbiting the Earth. Since the system is in free fall, by the equivalence principle, the quantum system is local in flat, gravity free space-time—it is screened from the gravitational field. For a slightly elliptical orbit, the gravitational potential will change with time. This leads to the energy levels of the quantum system developing sidebands which is the signature for this version of the Aharonov-Bohm effect. This contrasts with the normal signature of the Aharonov-Bohm effect of shifting of interference fringes.

We explore the new physics phenomena of gravidynamics governed by the inhomogeneous spin gauge symmetry based on the gravitational quantum field theory. Such a gravidynamics enables us to derive the generalized Einstein equation and an equation beyond it. To simplify the analyses, we linearize the dynamic equations of gravitational interaction by keeping terms up to the leading order in the dual gravigauge field. We then apply the linearized dynamic equations into two particular gravitational phenomena. First, we consider the linearized equations in the absence of source fields, which is shown to have five physical propagating polarizations as gravitational waves, i.e., two tensor modes, two vector modes, and one scalar, instead of two tensor polarizations in the general relativity. Second, we examine the Newtonian limit in which the gravitational fields and the matter source distribution are weak and static. By deriving the associated Poisson equation, we obtain the exact relation of the fundamental interaction coupling in the gravidynamics with the experimentally measured Newtonian constant. We also make use of nonrelativistic objects and relativistic photons to probe the Newtonian field configurations. In particular, the experiments from the gravitational deflection of light rays and the Shapiro time delay can place stringent constraints on the linearized gravidynamics in the gravitational quantum field theory.

The concept of cracking refers to the tendency of a fluid distribution to “split,” once it abandons the equilibrium. In this manuscript we develop a general formalism to describe the occurrence of cracking within a dissipative fluid distribution, in comoving coordinates. The role of dissipative processes in the occurrence of cracking is brought out. Next, we relate the occurrence of cracking with the concept of complexity for self-gravitating objects defined in Herrera [Phys. Rev. D 97, 044010 (2018)], Herrera et al. [Phys. Rev. D 98, 104059 (2018)], and Herrera et al. [Eur. Phys. J. C 80, 631 (2020)]. More specifically we relate the occurrence of cracking with the condition of the vanishing of the scalar function intended to measure the complexity of the fluid distribution (the complexity factor). We also relate the occurrence of cracking with the specific mode of leaving the equilibrium. Thus, we prove that leaving the equilibrium in either the homologous ($H$) or the quasihomologous regime ($QH$) prevents the occurrence of cracking. Also, it is shown that imposing the condition of vanishing complexity factor alone (independently of the mode of leaving the equilibrium) prevents the occurrence of cracking in the nondissipative geodesic case, and in the nondissipative isotropic case. These results bring out further the relevance of the complexity factor and its related definition of complexity in the study of self-gravitating systems.