Implementing the axion concept in the context of 3-3-1 extensions of the Standard Model leads to richer properties than in the simpler axion setups, and they are related to the Dirac neutrino seesaw mechanism. In this way, the smallness of neutrino masses, the strong $CP$ problem, the nature of dark matter, and the number of families all have a common origin. Besides having an enhanced coupling to photons, our revamped axion can also be distinguished from both Dine-Fischler-Srednicki-Zhitnisky and Kim-Shifman-Vainshtein-Zakharov axions through its couplings to fermions. The latter lead to interesting phenomenological consequences, including flavor-changing axion-emitting two-body $K$, $B$, and $D$ meson decays.

The separation of the hadronic vacuum polarization contribution to the muon anomalous magnetic moment into Euclidean windows allows for a tailored approach to address the different dominant challenges at short, intermediate, and long distances. We present a novel approach to compute the short-distance window without the need for using perturbative QCD. We combine a quenched continuum extrapolation using 18 lattice spacings ($1.6\mathrm{GeV}\lesssim a^{-1}\lesssim 6.1\mathrm{GeV}$) with a separate continuum extrapolation of the sea quark effects. This method allows for the computationally expensive sea quark effects to be estimated using only a smaller number of ensembles at coarser lattice spacings, while largely confining the logarithmic dependency of the continuum extrapolation to the quenched component.

We investigate the sextet $b$-baryon decay processes ${\mathrm{\Omega }}_b\to J/\psi {\mathrm{\Omega }}^{(*)}$, where ${\mathrm{\Omega }}^{*}$ represents the $1P$-, $1D$- and $2S$-wave excited $\mathrm{\Omega }$ hyperons in the spectroscopy. Using the constituent quark model, we obtain $\mathcal{B}({\mathrm{\Omega }}_b\to J/\psi \mathrm{\Omega })=8.8\times {10}^{-4}$, which agrees with the previous studies to the order of magnitude. By identifying $\mathrm{\Omega }(2012)$ as $\mathrm{\Omega }(1^2{P}_{3/2^{-}})$, $\mathcal{B}({\mathrm{\Omega }}_b\to J/\psi \mathrm{\Omega }(2012))=1.1\times {10}^{-3}$ can be similarly significant. Additionally, $\mathrm{\Omega }(1^2{D}_{5/2^{+}})$ and $\mathrm{\Omega }(1^4{D}_{3/2^{+}},1^4{D}_{5/2^{+}})$ states exhibit production rates of 0.5, and (0.6, 0.8), respectively, relative to their ground-state counterpart. Notably, our findings suggest that $\mathcal{B}({\mathrm{\Omega }}_b\to J/\psi \mathrm{\Omega }(2^2{S}_{1/2^{+}},2^4{S}_{3/2^{+}}))$ are as large as $(4.5,20)\times {10}^{-4}$, making them accessible to experiments at LHCb.

The jet cross section and jet-substructure observables in $p+p$ collisions at $\sqrt{s}=200\mathrm{GeV}$ were measured by the PHENIX Collaboration at the Relativistic Heavy Ion Collider (RHIC). Jets are reconstructed from charged-particle tracks and electromagnetic-calorimeter clusters using the anti-$k_t$ algorithm with a jet radius of $R=0.3$ for jets with transverse momentum within $8.0<p_T<40.0\mathrm{GeV}/c$ and pseudorapidity $|\eta |<0.15$. Measurements include the jet cross section, as well as distributions of SoftDrop-groomed momentum fraction ($z_g$), charged-particle transverse momentum with respect to jet axis ($j_T$), and radial distributions of charged particles within jets ($r$). Also measured was the distribution of $\xi =-\ln (z)$, where $z$ is the fraction of the jet momentum carried by the charged particle. The measurements are compared to theoretical next-to and next-to-next-to-leading-order calculations, the pythia and herwig event generators, and to other existing experimental results. Indicated from these measurements is a lower particle multiplicity in jets at RHIC energies when compared to models. Also noted are implications for future jet measurements with sPHENIX at RHIC as well as at the future Electron-Ion Collider.

We investigate the absorption of massless scalar, electromagnetic, and gravitational fields propagating in the Schwarzschild black hole geometry. Using complex angular momentum techniques, we first derive a representation of the absorption cross section that separates it into smooth background integrals and a discrete Regge pole series. This decomposition reveals the physical mechanisms underlying black hole absorption, including classical capture, surface wave interference near the photon sphere, and subleading background effects. We then construct a refined high-frequency analytical approximation that captures both the dominant oscillations and the fine structure of the absorption spectra for scalar, electromagnetic, and gravitational fields, incorporating spin-dependent phase corrections and higher-order effects. In addition, we provide a simplified expression that generalizes the sinc approximation to describe the leading oscillations for electromagnetic and gravitational fields. Our analysis offers a unified semiclassical interpretation of black hole absorption, combining geometric optics, surface wave dynamics, and resonant phenomena encoded by the Regge pole structure.

The coalescence of binary black holes (BBHs) provides a unique arena to test general relativity (GR) in the dynamical, strong-field regime. To this end, we present pSEOBNRv5PHM, a parametrized, multipolar, spin-precessing waveform model for BBHs in quasicircular orbits, built within the effective-one-body formalism. Compared to its predecessor, pSEOBNRv4HM, our model introduces parametrized deviations from GR not only in the plunge-merger-ringdown stages, but also in the inspiral phase through modifications to the conservative dynamics. Additionally, it incorporates, for the first time, spin-precession effects. The free deviation parameters can be used to perform null tests of GR using current and future gravitational-wave observations. We validate pSEOBNRv5PHM through Bayesian parameter estimation, focusing on the quasinormal-mode frequency and damping time of the $(\ell ,m,n)=(2,2,0)$ mode. Our analysis of synthetic signals from numerical-relativity (NR) simulations of highly precessing BH mergers shows that, while pSEOBNRv5PHM correctly recovers consistency with GR, neglecting spin precession can lead to false detections of deviations from GR even at current detector sensitivity. Conversely, when analyzing a synthetic signal from a NR simulation of a binary boson-star merger, the model successfully identifies a deviation from a GR BBH signal. Finally, we reanalyze 12 events from the third Gravitational Wave Transient Catalog. Using a hierarchical combination of these events, we constrain fractional deviations in the frequency and damping time of the (2,2,0) quasinormal-mode to $\delta f_{220}=0.00_{-0.06}^{+0.06}$ and $\delta {\tau }_{220}=0.15_{-0.24}^{+0.26}$ at 90% credibility. These results are consistent with those from the LIGO-Virgo-KAGRA Collaboration, which did not account for spin-precession effects.

Within an inherently classical perspective, there is always an unavoidable energy cost associated with the information deletion and this common lore is at the heart of the Landauer conjecture that does not impose, per se, any relevant limit on the information acquisition. Although such a mindset should generally apply to systems of any size, its quantum mechanical implications are particularly intriguing and, for this reason, we examine here a minimal physical structure where the system and the environment are described, respectively, by a pair of quantum oscillators coupled by an appropriate Hermitian interaction able to amplify the entropy of the initial state. Since at the onset of the dynamical evolution the system is originally in a pure state, its entropy variation is always positive semidefinite and the Landauer conjecture should not impose any constraint. Nonetheless, provided the quantum amplification is effective, it turns out that the entropy variation of the system always undershoots the heat transferred to the environment. When the initial thermal state of the environment is characterized by a chemical potential, the entropy growth is bounded both by the particles and by the heat flowing to the environment. The limits deduced in the quantum thermodynamical framework are also scrutinized from a field theory standpoint where species of different spins are copiously produced (especially in a cosmological context) thanks to the rapid variation of the space-time curvature.

It is possible for asymmetric dark matter (ADM) to accumulate in neutron star interiors and affect their global properties. Considering the effects of this accumulation, neutron star mass-radius measurements can deliver new insights into the cold dense matter equation of state (EoS). In this paper, we employ Bayesian parameter estimation using real and synthetic neutron star mass-radius data to infer constraints on the combined baryonic matter and fermionic ADM EoS, where the fermionic ADM forms a core in the neutron star interior. Using currently available mass-radius data, we find that the lower bound of the ratio between the ADM effective self-repulsion strength ($g_{\chi }/m_{\varphi }$) and particle mass ($m_{\chi }$) can be constrained at the 68% (95%) credible level to ${10}^{-6.59}$ (${10}^{-7.77}$). We also find that, if neutron star mass-radius measurement uncertainties are reduced to the 2% level, the constraints on the lower bound of the ratio of $g_{\chi }/m_{\varphi }$ to $m_{\chi }$ can be improved to ${10}^{-6.49}$ and ${10}^{-7.68}$ at the 68% and 95% credible levels, respectively. However, all other combinations, of $m_{\chi }$, $g_{\chi }$, and the ADM mass-fraction, $F_{\chi }$ (i.e., the ratio of the gravitational ADM mass to the gravitational mass of the neutron star), are unconstrained. Furthermore, in the pressure-energy density and mass-radius planes, the inferences which include the possibility of fermionic ADM cores are nearly identical with the inferences that neglect fermionic ADM for $F_{\chi }\le 1.7\%$ and neutron star mass-radius uncertainties $\ge 2\%$. Therefore, we find that neutron star mass-radius measurements can constrain the ratio of $g_{\chi }/m_{\varphi }$ to $m_{\chi }$. Moreover, since the pressure-energy density and mass-radius posteriors which include fermionic ADM overlap with those that neglect fermionic ADM, we find that neutron stars with ADM are indistinguishable from purely baryonic stars. This implies that neutron stars with ADM are equally as consistent with the available mass-radius data as neutron stars without ADM.

We study real-time nucleation in perturbative high-temperature quantum field theories. Specifically, we incorporate the evolution of thermally fluctuating plasma driven out of equilibrium by nucleation. This plasma forms the thermal bath for the nucleating bubbles, and its off-equilibrium dynamics backreact on the bubbles, modifying the nucleation rate. Utilizing kinetic Boltzmann descriptions for the plasma particles, we derive that the nucleation rate in high-temperature quantum field theories is described by Langer’s rate formula with effects arising from the off-equilibrium plasma, unaccounted for in Linde’s thermal rate. Importantly, we establish a connection to equilibrium computations of nucleation rates, particularly with the effective field theory approach, showing that they correctly capture the leading parts of the logarithm of the rate. We also show that the dominant modifications to the nucleation rate from a light bosonic quantum field arise from its corresponding long-wavelength classical modes, rather than the associated hard particles. This work provides a foundation for further studies of off-equilibrium effects in nucleation rates for realistic Standard Model extensions.

We utilize stochastic hydrodynamics to study correlations and fluctuations of baryon charge in high-energy heavy-ion collisions. The baryon charge fluctuations are important observables to probe the quantum chromodynamics (QCD) phase diagram, yet a dynamical description with stochastic hydrodynamics remains challenging due to numerical instabilities and high computational demands. In this work, we employ a linearized approach, allowing us to separately simulate the background energy-momentum evolution of a charge-neutral fluid and the stochastic baryon transport processes, thereby largely reducing computational cost while maintaining sufficient accuracy. We implement this linearized stochastic charge evolution in the $3+1\mathrm{D}$ viscous hydrodynamic code music, and compare numerical results to (semi-)analytical solutions for stochastic charge transport in Bjorken flow. We find that it nicely describes the two-point correlation of $1+1\mathrm{D}$ analytical solutions for various equations of state and transport coefficients. In particular, the hydrodynamic calculations demonstrate how different rapidity separations probe charge fluctuations originating at different times of the evolution. We also investigate the net baryon correlations after the Cooper-Frye freeze out, which show good consistency with the analytical calculations and indicate that these fluctuation-induced correlations are sensitive to the baryon diffusion coefficient.

The bottomonium spectrum is systematically studied within an unquenched quark model. Based on a good description of both the masses and widths for the well-established states, we further give predictions for the higher $S$-, $P$-, and $D$-wave bottomonium states up to a mass region of $\sim 11.3\mathrm{GeV}$. For the vector states, the $S\text{−}D$ mixing and dielectron decays are studied. Additionally, to understand the role of the higher vector resonances in the $e^{+}{e}^{-}$ annihilation reaction, we evaluate the cross section by combining our quark model predictions for the mass, dielectron, and strong decay properties. It is found that (i) The mass shifts of the high-$b\overline{b}$ states due to the coupled-channel effects are on the order of a few tens of MeV; most of the high-lying resonances contain significant non-$b\overline{b}$ components. (ii) The ${\mathrm{\Upsilon }}_1(3D,5D,6D)$ states significantly mix with $\mathrm{\Upsilon }(4S,6S,7S)$, respectively, which is mainly induced by the intermediate hadronic loops. (iii) The non-$b\overline{b}$ components will lead a significant suppression for the dielectron decay widths of some vector resonances. (iv) The threshold effects of open-bottom meson pairs can cause rich bump structures in the cross section of $e^{+}{e}^{-}\to b\overline{b}$. Our model shows that the $\mathrm{\Upsilon }(10753)$ may arise from threshold effects due to the strong coupling between $\mathrm{\Upsilon }(4S)$ and ${\overline{B}}^{*}{B}^{*}$.

The nonlinear $\mathrm{\Sigma }$ model minimally coupled with Maxwell theory in $3+1$ dimensions possesses a topologically nontrivial sector characterized by lasagnalike configurations. We demonstrate that, when a specific quantization condition is met, the associated second-order field equations admit a first-order Bogomol’nyi-Prasad-Sommerfield system. This discloses the existence of a ($1+1$)-dimensional supersymmetric extension with $\mathcal{N}=2$ supercharges. We examine its imprint on the time-dependent regime, with particular emphasis on the transition from integrability to chaos.

We revisit the calculation of the evolution equations for four unpolarized twist-3 transverse momentum dependent (TMD) parton distribution functions (PDFs) at $\mathcal{O}({\alpha }_s)$. Unlike the existing calculations in the literature, which are based on the background field method, we derive the evolution equations directly through diagram expansion. Additionally, instead of using the $\delta$ regulator, we employ the exponential regulator to regularize the rapidity divergences. We find that the evolutions of the four twist-3 TMD PDFs are governed by eight homogeneous equations. Our evolution kernels agree with one set of results in the literature, but differ from another by a sign. Considering the advantages of the exponential regulator in high-order perturbative calculations, our results are crucial for computing the twist-3 TMD PDFs at $\mathcal{O}({\alpha }_s^2)$.

Fuzzy dark matter (FDM) is a compelling candidate for dark matter, offering a natural explanation for the structure of diffuse low-mass haloes. However, the canonical FDM model with a mass of ${10}^{-22}\mathrm{eV}$ encounters challenges in reproducing the observed diversity of dwarf galaxies, except for possibly scenarios where strong galactic feedback is invoked. The introduction of multiple-field FDM can provide a potential resolution to this diversity issue. The theoretical plausibility of this dark matter model is also enhanced by the fact that multiple axion species with logarithmically distributed mass spectrum exist as a generic prediction of string theory. In this paper, we consider the axiverse hypothesis and investigate nonlinear structure formation in the two-field fuzzy dark matter (2FDM) model. Our cosmological simulation with an unprecedented resolution and self-consistent initial conditions reveals the diverse structures of dark matter haloes in the 2FDM model for the first time. Depending on the formation time and local tidal activities, late-time haloes can host solitons of nested cores or solitons of one dominant species.

We examine the mixture equivalence principle (MEP), which states that proper and improper mixed states with the same density matrix are always experimentally indistinguishable, and a weaker version, which states that this is sometimes true in gravity theories. We point out that Møller-Rosenfeld semiclassical gravity violates the weak MEP and that nonlinear extensions of quantum mechanics violate the MEP. We further demonstrate that modifications of the Born rule in quantum theory also typically violate the MEP. We analyze such violations in the context of thermal baths, where proper and improper thermal states induce different physical situations. This has significant implications in the context of black hole physics. We argue that Møller-Rosenfeld semiclassical gravity is not the semiclassical limit of quantum gravity in the context of black hole spacetimes, even in the presence of $N\gg 1$ matter fields.

Based on periodic orbit theory, we address the individual-system versus ensemble interpretation of quantum gravity from a quantum chaos perspective. To this end, we show that the spectrum of geodesic motion on high-dimensional hyperbolic manifolds, described by the Selberg trace formula, displays a Schwarzian ($\sinh 2\pi \sqrt{E}$) mean level density. Due to its chaotic classical limit, this quantum system also shows all universal signatures of quantum chaos. These two properties imply a possible duality to Jackiw-Teitelboim-type quantum gravity at the level of a single system instead of an ensemble of systems like matrix- and Sachdev-Ye-Kitaev models. Moving beyond the universal regime, we show how the full wormhole geometry on the gravity side emerges from the discreteness of the set of periodic orbits. Thereby, we take initial steps towards a duality between gravitational and mesoscopic chaotic quantum systems through the topological, respectively, periodic orbit expansions of their correlators.

The Unruh effect is a well-understood phenomenon in which a quantum field in a vacuum state within Minkowski spacetime appears thermally populated for a uniformly accelerating Rindler observer. In this article, we derive a variant of the Unruh effect involving two distinct accelerating observers and aim to address the following questions: (i) Is it possible to have a particle excitation for a selective subset of momentum modes for the case of massless scalar fields, and (ii) Is it possible to excite only the left-chiral massless fermions while keeping right-chiral fermionic fields in an unexcited state or vice versa? To this end, we consider a Rindler wedge $R_1$ constructed from a class of accelerating observers and another Rindler wedge $R_2$ (with $R_2\subset R_1$) constructed from another class of accelerating observers such that the wedge $R_2$ is displaced along a null direction with respect to $R_1$ by a parameter $\mathrm{\Delta }$. By first considering a massless scalar field in the $R_1$ vacuum, we demonstrate that if we choose the displacement $\mathrm{\Delta }$ along one null direction, the positive momentum modes are thermally populated, whereas negative momentum modes remain unaffected (and vice versa if we choose the displacement along the other null direction). We then consider a massless fermionic field in a vacuum state in $R_1$ and show that the reduced state in $R_2$ is such that the left-chiral fermions are excited and are thermal for large frequencies. In contrast, the right-chiral fermions have negligible particle density (and vice versa). We argue that the null-shifted Rindler spacetime considered in this article is a good toy model for understanding a class of evolving horizons. Additionally, based on our work, we hypothesize that massless fermions underwent selective chiral excitations during the radiation-dominated era of cosmology.

We start with the consideration of the loop effects for light fields with nonzero mass in the expanding Poincaré patch of de Sitter spacetime. We derive the Dyson-Schwinger equation, which sums up the leading infrared (growing with time) loop corrections in certain limit for small initial perturbations above the Bunch-Davies state. The solution of this equation shows the destiny of the initial state at the future infinity. Then we discuss the case of the contracting Poincaré patch and global de Sitter spacetime and briefly the case of different initial conditions in the expanding Poincaré patch.

We present an explicitly gauge-invariant observable of any general gravitational perturbation, $h_{\mu \nu }$ [not necessarily due to gravitational waves (GWs)], in a laser interferometry-based GW detector, identifying the signature as the proper time elapsed of the beamsplitter observer, between two events: when a photon passes through the beamsplitter, and when the same photon returns to the beamsplitter after traveling through the interferometer arm and reflecting off the far mirror. Our formalism applies to simple Michelson interferometers and can be generalized to more advanced setups. We demonstrate that the proper time observable for a plane GW is equivalent to the detector strain commonly used by the GW community, though now the common framework can be easily generalized for other types of signals, such as dark matter clumps or spacetime fluctuations from quantum gravity. We provide a simple recipe for computing the proper time observable for a general metric perturbation in linearized gravity and explicitly show that it is invariant under diffeomorphisms of the perturbation, as any physical observable should be.

In this work we analyze the polarization observational properties of solitonic boson stars orbited by spherical hot spots emitting synchrotron radiation from a thermal distribution of electrons. We consider three boson star configurations with different compactnesses ranging from a dilute model with a large radius to an ultracompact model capable of holding null bound orbits. We observe that the polarimetric imprints of the primary images for all models are comparable to those of the Schwarzschild spacetime, and thus any potentially distinguishable differences must arise from the additional structure of secondary and plunge-through images. For low inclination (20°) observations, we find that the two QU loops of the least compact model are in contradiction with the current ALMA and GRAVITY observations and effectively exclude the possibility of Sgr A* being a dilute solitonic boson star. For high inclination (80°) observations, both the electric vector position angle and the QU loops present large qualitative deviations from the Schwarzschild black hole for all models analyzed. Our results emphasize the suitability of polarimetry as a framework to test the nature of supermassive compact objects with future observations, especially at high inclination.