Scalar, vector, and tensor perturbations on the Kerr spacetime are governed by equations that can be solved by separation of variables, but the same is not true in generic stationary and axisymmetric geometries. This complicates the calculation of black-hole quasinormal mode frequencies in theories that extend/modify general relativity, because one generally has to calculate the eigenvalue spectrum of a two-dimensional partial differential equation (in the radial and angular variables) instead of an ordinary differential equation (in the radial variable). In this work, we show that if the background geometry is close to the Kerr one, the problem considerably simplifies. One can indeed compute the quasinormal mode frequencies, at least at leading order in the deviation from Kerr, by solving an ordinary differential equation subject to suitable boundary conditions. Although our method is general, in this paper we apply it to scalar perturbations on top of a Kerr black hole with an anomalous quadrupole moment, or on top of a slowly rotating Kerr background.

In this article, we study the structure of static spherical stars made up of a nonrelativistic polytropic fluid in linearized higher-curvature theories of gravity (HCG). We first formulate the modified Lane–Emden (LE) equation for the stellar profile function in a gauge-invariant manner, finding it boils down to a sixth-order differential equation in the generic case of HCG, while it reduces to a fourth-order equation in two special cases, reflecting the number of additional massive gravitons arising in each theory. Moreover, the existence of massive gravitons renders the nature of the boundary-value problem unlike the standard LE: some of the boundary conditions can no longer be formulated in terms of physical conditions at the stellar center alone, but some demands at the stellar surface necessarily come into play. We present a practical scheme for constructing solutions to such a problem and demonstrate how it works in the cases of the polytropic index $n=0$ and 1, where analytical solutions to the modified LE equations exist. As physical outcomes, we clarify how the stellar radius, mass, and Yukawa charges depend on the theory parameters and how these observables are mutually related. Reasonable upper bounds on the Weyl-squared correction are obtained.

We consider the Galilean limit of conformal algebra for spin-2 and spin-3 fields and study the gauge theory of these algebras. We analyze the equations of motion and obtain the spectra of the theories.

We present a phenomenological framework for starburst-driven neutrino production via proton-proton collisions and apply it to (ultra)luminous infrared galaxies (U/LIRGs) in the Great Observatories All-Sky LIRG Survey (GOALS). The framework relates the infrared luminosity of a GOALS galaxy, derived from consistently available Herschel Space Observatory data, to the expected starburst-driven neutrino flux. The model parameters that define this relation can be estimated from multiwavelength data. We apply the framework in a case study to the LIRG NGC 3690 (Arp 299, Mrk 171) and compare the obtained neutrino fluxes to the current sensitivity of the IceCube Neutrino Observatory. Using our framework, we conclude that the neutrino emission in the LIRG NGC 1068, recently presented as the first steady IceCube neutrino point source, cannot be explained by a starburst-driven scenario and is therefore likely dominated by the active galactic nucleus in this galaxy. In addition to the single-source investigations, we also estimate the diffuse starburst-driven neutrino flux from GOALS galaxies and the total LIRG population over cosmic history.

We propose a new family structure for the Standard Model fermions, where the muon is assigned to the third family, taking the placeholder from the tau lepton. This reassignment, which is a mere choice of convention in the Standard Model, becomes physically meaningful in the presence of new physics assuming a direct link between quarks and leptons. In fact, when quarks and leptons are coupled by new interactions, the choice of which lepton is assigned to a particular quark generation brings physical consequences, revealing potentially meaningful patterns in the masses and mixings, while pointing to precise and testable predictions for experiments.

We point out that there is a stable configuration of metal plates where the Casimir force is vanishing in axion electrodynamics. We consider a concrete setup involving Weyl semimetals, which hosts an axionlike effect on the electromagnetism, toward the measurement of the axionic effect on the Casimir force. Our setup realizes zero Casimir force between metals and may be useful for the search for a new force mediated by light particles at the micrometer scale.

Many collider searches have attempted to detect the Higgs boson decaying to a photon and an invisible massless dark photon. For the branching ratio to this channel to be realistically observable at the LHC, there must exist new mediators that interact with both the standard model and the dark photon. In this paper, we study experimental and theoretical constraints on an extensive set of mediator models. We show that these constraints limit the Higgs branching ratio to a photon and a dark photon to be far smaller than the current sensitivity of collider searches.

For the first time, we present a lattice QCD determination of Mellin moments of unpolarized generalized parton distributions (GPDs) of the proton from an analysis of the quasi-GPD matrix elements within the short-distance factorization framework. We perform our calculation on an $N_f=2+1+1$ twisted mass fermions ensemble with a clover improvement at lattice spacing $a=0.093\mathrm{fm}$ and a pion mass of $m_{\pi }=260\mathrm{MeV}$. Focusing on the zero-skewness case, the isovector and isoscalar quasi-GPDs are calculated from the ${\gamma }_0$ definition, as well as a recently proposed Lorentz-invariant definition. We utilize data on both symmetric and asymmetric kinematic frames, which allows us to obtain the Mellin moments for several values of the momentum transfer, $-t$, in the range 0.17 to $2.77{\mathrm{GeV}}^2$. We use the ratio scheme for GPDs, i.e. renormalization group invariant ratios with leading-twist factorization formula and perturbatively calculated matching coefficients up to the next-next-to-leading order (NNLO) to extract Mellin moments of GPDs, which are consistent with renormalization-group improved results. We compare our determination from quasi-GPDs with the results extracted using standard calculations of Mellin moments of local operators, specifically those related to the electromagnetic and gravitational form factors. We estimated the moments of GPDs up to the fifth ones for the first time. By extrapolating the Mellin moments to $-t=0$, we obtained the quark charges, momentum fraction, as well as the angular momentum contributions to the proton spin. The impact parameter space interpretation of the GPD moments is discussed, which provides insights into the spatial distribution of unpolarized quarks and their correlations in the transverse plane of an unpolarized or transversely polarized proton.

In this work, we systematically study the Okubo-Zweig-Iizuka-allowed two-body strong decay properties of $1P$- and $1D$-wave ${\mathrm{\Sigma }}_c$ baryons within the $j\text{−}j$ coupling scheme in the framework of the quark pair creation model. For a comparison, we also give the predictions of the chiral quark model. Some model dependencies can be found in the predictions of two models. The calculations indicate that: (i) The $1P$-wave $\lambda$-mode ${\mathrm{\Sigma }}_c$ states most likely to be relatively narrow states with a width of $\mathrm{\Gamma }<80\mathrm{MeV}$. Their main decay channels are ${\mathrm{\Lambda }}_c\pi$, or ${\mathrm{\Sigma }}_c\pi$, or ${\mathrm{\Sigma }}_c^{*}\pi$. The $1P$-wave $\rho$-mode states most might be broad states with a width of $\mathrm{\Gamma }\sim 100–200\mathrm{MeV}$. They dominantly decay into ${\mathrm{\Sigma }}_c\pi$ and ${\mathrm{\Sigma }}_c^{*}\pi$ channels. Some evidences of these $1P$-wave states are most likely to be observed in the ${\mathrm{\Lambda }}_c\pi$ and ${\mathrm{\Lambda }}_c\pi \pi$ invariant mass spectra around the energy range of 2.75–2.95 GeV. (ii) The $1D$-wave $\lambda$-mode ${\mathrm{\Sigma }}_c$ excitations may be moderate states with a width of about dozens of MeV. The $1D$-wave $\lambda$-mode states mainly decay into the $1P$-wave charmed baryon via the pionic decay processes. Meanwhile, several $1D$-wave $\lambda$-mode states have significant decay rates into $DN$ or $D^{*}N$. Hence, the $DN$ and $D^{*}N$ are likely to be interesting channels for experimental exploration. (iii) Furthermore, the two $1D$-wave $\rho$-mode excitations ${\mathrm{\Sigma }}_c|J^P=5/2^{+},3{⟩}_{\rho \rho }$ and $|J^P=7/2^{+},3{⟩}_{\rho \rho }$ are most likely to be fairly narrow state with a width of dozens of MeV, and they mainly decay into ${\mathrm{\Lambda }}_c\pi$. Some evidences of them might be observed in the ${\mathrm{\Lambda }}_c\pi$ invariant mass spectra around the energy range of 3.1–3.2 GeV.

We propose a scheme to identify the region for the hadron-quark phase transition in cold dense strong interaction matter (neutron star matter) to take place with astronomical observations. To study the property of the first-order phase transition in the matter, we take the sound speed as the interpolation objective to construct the equation of state of the matter involving the hadron and quark coexisting phase. We show the feature of the sound speed in the matter with two conservation charges and a first-order phase transition. With the maximum mass, the tidal deformability and the radius of neutron stars being taken as calibration quantities, the baryon chemical potential region for the phase transition to occur is constrained to a narrow range, and the most probable value of the phase transition chemical potential is found.

This study investigates the resonance $\omega {\chi }_{bJ}$, recently discovered in $e^{+}{e}^{-}$ collisions with a center-of-mass energy of $\sqrt{s}=10.745\mathrm{GeV}$ and reported by the Belle II Collaboration, to explore its potential identification with the previously reported $\mathrm{\Upsilon }(10753)$. We consider both the traditional $\mathrm{\Upsilon }(nS)$ meson and the exotic tetraquark $b\overline{q}q\overline{b}$ state with $J^P=1^{-}$, employing the chiral quark model to solve the Schrödinger equation. Our calculations demonstrate that the mass of $\mathrm{\Upsilon }(5S)$, $\mathrm{\Upsilon }(4S)$, and $\mathrm{\Upsilon }(3D)$, as potential two-quark state candidates, are inconsistent with the experimentally observed $\mathrm{\Upsilon }(10753)$, effectively excluding the possibility of $\mathrm{\Upsilon }(10753)$ as a two-quark state in our model. Furthermore, we employ the Gaussian expansion method to investigate the tetraquark structure of the resonance, including two molecular structures ($b\overline{b}\text{−}q\overline{q}$, $b\overline{q}\text{−}q\overline{b}$) and a diquark-antidiquark structure ($\overline{b}\overline{q}\text{−}qb$), and perform a full-channel coupling using the real-scaling method. Our investigation yields a total of seven resonant states, with one state having an energy of $10761\pm 7\mathrm{MeV}$ and a width of $10.8\pm 5.2\mathrm{MeV}$, which is a promising candidate for the experimentally observed $\mathrm{\Upsilon }(10753)$. Furthermore, we report no resonances in the energy range below 10.6 GeV, while several resonances were found in the 10.8–10.9 GeV range. These findings suggest the need for future experiments to search for additional resonant states in this energy range, potentially providing further support for our model.

In the phenomenology of strong interactions most physical states acquire a substantial width, and thus can only be defined in a model-independent way by pole positions and residues of the $S$-matrix. This information is incorporated in the Källén-Lehmann representation, whose spectral function characterizes the shape of the resonance and can be constrained by the dominant decay channels. Here, we argue that similar effects become important whenever beyond-the-Standard-Model particles possess a sizable decay width—as possible for instance in cases with a large branching fraction to a dark sector or strongly coupled scenarios—and show how their widths can be incorporated in the calculation of loop observables. As an application, we consider the anomalous magnetic moment of the muon, including both the direct effect of new physics and the possible indirect impact of a broad light $Z^{\prime }$ on $e^{+}{e}^{-}\to \text{hadrons}$ cross sections. Throughout, we provide results for a general spectral function and its reconstruction from the one-loop imaginary part, where the latter captures the leading two-loop effects.

The study of long-range effects arising from the higher order exchange of massless particles via summation of Feynman diagrams is well known, but recently it has been shown that the use of on-shell methods can provide a streamlined route to the calculation of both electromagnetic and gravitational effects. In this paper we demonstrate that the use of on-shell methods yields a similar simplification in the evaluation of higher order effects in the case of mixed electromagnetic and gravitational scattering.

We calculate the branching ratios and $CP$ violations for $B\to K\pi$ decays in a modified perturbative QCD approach based on $k_T$ factorization. The resummation effect of the transverse momentum regulates the end-point singularity. Using the $B$ meson wave function that is obtained in the relativistic potential model, the soft contribution cannot be suppressed effectively by the Sudakov factor. Soft scale cutoff and soft $BK$, $B\pi$, and $K\pi$ form factors have to be introduced. The most important next-to-leading-order contributions from the vertex corrections, the quark loops, and the magnetic penguins are also considered. In addition, the contribution of the color-octet hadronic matrix element is included which is essentially of long-distance dynamics. Our predictions for all the branching ratios and most $CP$ violations are well consistent with the experimental data. Especially the theoretical result of the dramatic difference between the $CP$ violations of $B^{+}\to K^{+}{\pi }^0$ and $B^0\to K^{+}{\pi }^{-}$ is in good agreement with the experimental measurement; therefore, the $K\pi$ puzzle in $B$ decays can be resolved in our way of the modified perturbative QCD approach.

The LUX-ZEPLIN experiment recently reported limits on WIMP-nucleus interactions from its initial science run, down to $9.2\times {10}^{-48}{\mathrm{cm}}^2$ for the spin-independent interaction of a $36\mathrm{GeV}/{\mathrm{c}}^2$ WIMP at 90% confidence level. In this paper, we present a comprehensive analysis of the backgrounds important for this result and for other upcoming physics analyses, including neutrinoless double-beta decay searches and effective field theory interpretations of LUX-ZEPLIN data. We confirm that the in-situ determinations of bulk and fixed radioactive backgrounds are consistent with expectations from the ex-situ assays. The observed background rate after WIMP search criteria were applied was $(6.3\pm 0.5)\times {10}^{-5}\mathrm{events}/{\mathrm{keV}}_{ee}/\mathrm{kg}/\mathrm{day}$ in the low-energy region, approximately 60 times lower than the equivalent rate reported by the LUX experiment.

For a cosmological first-order phase transition in the early Universe, the associated stochastic gravitational wave background is usually dominated by sound waves from plasma fluid motions, which have been analytically modeled as a random superposition of freely propagating sound shells but with the force by the scalar field that produces the self-similar profile removed. In this Letter, we propose a new analytic sound shell model by focusing on the forced propagating contribution from the initial collision stage of sound shells when their self-similar profiles are still maintained by the moving bubble walls. We reproduce the causal $k^3$ scaling in the infrared consistent with numerical simulations, and also recover the broad dome in the power spectrum first observed in numerical simulations. The total sound waves should contain both contributions from forced collisions and free propagation of sound shells at early and late stages of the phase transition, respectively.

The LHAASO Collaboration has reported their observation of very high energy photons ($E_{\gamma }^{\max }\simeq 18\mathrm{TeV}$) from the gamma-ray burst GRB221009A. The sterile neutrino that involves both mixing and a transition magnetic moment may be a viable explanation for these high energy photon events. However, we demonstrate that such a solution is strongly disfavored by the cosmic microwave background and big bang nucleosynthesis in standard cosmology.

The first hidden-charm pentaquark candidate with strangeness, $P_{\psi s}^{\mathrm{\Lambda }}(4338)$, was recently discovered in $B^{-}\to J/\psi \mathrm{\Lambda }\overline{p}$ by the LHCb Collaboration. $P_{\psi s}^{\mathrm{\Lambda }}(4338)$ shows up as a bump at the ${\mathrm{\Xi }}_c\overline{D}$ threshold in the $J/\psi \mathrm{\Lambda }$ invariant mass ($M_{J/\psi \mathrm{\Lambda }}$) distribution. The $M_{J/\psi \mathrm{\Lambda }}$ distribution also shows a large fluctuation at the ${\mathrm{\Lambda }}_c{\overline{D}}_s$ threshold, hinting the existence of a possible $P_{\psi s}^{\mathrm{\Lambda }}(4255)$. In this work, we determine the $P_{\psi s}^{\mathrm{\Lambda }}(4338)$ and $P_{\psi s}^{\mathrm{\Lambda }}(4255)$ pole positions for the first time. For this purpose, we fit a $B^{-}\to J/\psi \mathrm{\Lambda }\overline{p}$ model to the $M_{J/\psi \mathrm{\Lambda }}$, $M_{J/\psi \overline{p}}$, $M_{\mathrm{\Lambda }\overline{p}}$, and $\cos {\theta }_{K^{*}}$ distributions from the LHCb simultaneously; ${\chi }^2/\mathrm{ndf}\sim 1.21$. Then we extract $P_{\psi s}^{\mathrm{\Lambda }}$ poles from a unitary ${\mathrm{\Xi }}_c\overline{D}\text{−}{\mathrm{\Lambda }}_c{\overline{D}}_s$ coupled-channel scattering amplitude built in the model. In our default fit, the $P_{\psi s}^{\mathrm{\Lambda }}(4338)$ pole is found at $(4338.2\pm 1.4)–(1.9\pm 0.5)i\mathrm{MeV}$ while the $P_{\psi s}^{\mathrm{\Lambda }}(4255)$ pole at $4254.7\pm 0.4\mathrm{MeV}$. The $P_{\psi s}^{\mathrm{\Lambda }}(4338)$ and $P_{\psi s}^{\mathrm{\Lambda }}(4255)$ are mostly ${\mathrm{\Xi }}_c\overline{D}$ bound and ${\mathrm{\Lambda }}_c{\overline{D}}_s$ virtual states, respectively. Through our analysis, the data disfavors a hypothesis of $P_{\psi s}^{\mathrm{\Lambda }}(4338)$ as merely a kinematical effect. This pole determination, which is important in its own right, sets a primary basis to study the nature of the $P_{\psi s}^{\mathrm{\Lambda }}$ states.

Consider a massless scalar field in Minkowski spacetime $\mathcal{M}$ in its vacuum state and two Rindler wedges $R_1$ and $R_2$. Here $R_2$ is shifted to the right of $R_1$ by a distance $\mathrm{\Delta }$. We, therefore, have $R_2\subset R_1\subset \mathcal{M}$ with the symbol $\subset$ implying a quantum subsystem. We find the reduced state in $R_2$ using two independent ways: (a) Evaluation of the reduced state of $R_2$ from vacuum state in $\mathcal{M}$, which yields a thermal density matrix. (b) First, evaluating the reduced state in $R_1$ from $\mathcal{M}$ yielding a thermal state in $R_1$, and subsequently evaluating the reduced state in $R_2$ from $R_1$. In this article, we attempt to address the question of whether both these independent paths yield the same reduced state in $R_2$. To that end, we devise a method that involves cleaving the Rindler wedge $R_1$ into two domains such that they form a thermofield double. One of the domains aligns itself along the wedge $R_2$ while the other is a diamond-shaped construction between the boundaries of $R_1$ and $R_2$. We conclude that both these independent methods yield two different answers, indicating that there are systems in which the reduced quantum state of a subsystem can be path dependent and hence not unique in a quantum field theoretic setting. We discuss the possible implications of our result in the context of quantum states outside a nonextremal black hole formed by collapsing matter.

This article provides a detailed investigation into the motion of the surrounding particles around a polymer black hole in loop quantum gravity (LQG). Using effective potential, the critical bound orbits and innermost stable circular orbits (ISCO) are analyzed. The study finds that the radii and angular momentum of the critical bound orbits decrease with an increase in the parameter $A_{\lambda }$ which labels the LQG effects, while the energy and angular momentum of the ISCO also decreases with an increase in $A_{\lambda }$. Based on these findings, we then explore the periodic orbits of the polymer black hole in LQG using rational numbers composed of three integers. Our results show that the rational numbers increase with the energy of particles and decrease with the increase of angular momentum based on a classification scheme. Moreover, compared to a Schwarzschild black hole, the periodic orbits in a polymer black hole in LQG consistently have lower energy, providing a potential method for distinguishing a polymer black hole in LQG from a Schwarzschild black hole. Finally, we also examine the gravitational wave radiations of the periodic orbits of a test object which orbits a supermassive polymer black hole in LQG, which generates intricate gravitational wave waveforms that can aid in exhibiting the gravitational structure of the system.