We investigate the properties of the hadron-quark mixed phase, often termed the pasta phase, expected to exist in the cores of massive neutron stars. To construct the equations of state (EoSs), we combine an analytical representation based on the Akmal-Pandharipande-Ravenhall EoS for hadronic matter with the MIT bag model featuring vector interactions for quark matter. For modeling the mixed phase, we utilize the compressible liquid drop model that consistently accounts for finite-size and Coulomb effects. Unlike most previous analyses that treated surface tension as a constant free parameter and neglected curvature tension, we employ microphysical calculations using the multiple reflection expansion formalism to determine these parameters, while also ensuring their self-consistency with the EoS. We construct an extensive set of mixed hybrid EoSs by varying model parameters, solve the stellar structure equations to obtain neutron star mass-radius relationships, and select the models that satisfy current astrophysical constraints. Our findings closely align with calculations using a constant surface tension in terms of EoS stiffness and resulting stellar structure. However, they reveal significant differences in the types of geometric structures and their prevalence ranges within the mixed phase. Specifically, curvature effects enhance the emergence of tubes and bubbles at high densities despite the large value of surface tension, while suppressing the existence of drops and rods at low densities.

We study the contributions for $K{\eta }^{\prime }$ pair originating from the scalar intermediate state $K_0^{*}(1430)$ in the three-body decays $B\to K{\eta }^{\prime }h$ ($h=\pi$, $K$) within the perturbative QCD approach. The contribution of $K_0^{*}(1430)\to K{\eta }^{\prime }$ is described by the Flatté formula with coupled channels $K\pi$, $K\eta$, and $K{\eta }^{\prime }$. The strong coupling constants $g_{K_0^{*}K{\eta }^{(\prime )}}$ are extracted from $g_{K_0^{*}K\pi }$ within flavor SU(3) symmetry. In spite of the strong depression by phase space near the threshold of $K{\eta }^{\prime }$, the $CP$ averaged branching fractions for the $B\to K_0^{*}(1430)h\to K{\eta }^{\prime }h$ decays are predicted to be on the order of ${10}^{-8}$ to ${10}^{-5}$, which are non-negligible for the corresponding three-body $B$ decays. Since the $\mathrm{K}\eta$ system is almost decoupled from the even-spin strange mesons under flavor SU(3) symmetry, those quasi-two-body $B$ decays with subprocess $K_0^{*}(1430)\to K\eta$ shall have quite small branching ratios and are not taken into account in this work. We also estimate that the branching fraction for $K_0^{*}(1430)\to K{\eta }^{\prime }$ is about one fifth of that for $K_0^{*}(1430)\to K\pi$. The predictions for the relevant decays are expected to be tested by the LHCb and Belle-II experiments in the future.

We propose a new method to search for exotic spin-spin interactions between electrons and nucleons using a diamond-based vector magnetometer. The vector magnetometer can be constructed from ensembles of nitrogen-vacancy centers along different axes in a diamond. The ${}^{14}\mathrm{N}$ nuclear spins of nitrogen-vacancy centers in the same diamond can be polarized through the dynamic nuclear polarization method to serve as spin sources. With the vector magnetometer, the sought-after exotic interactions can be distinguished from the magnetic dipole-dipole interaction. For the axion-mediated interaction $V_{PP}$, new upper bounds of the coupling $|g_P^e{g}_P^N|$ are expected within the force range from 10 nm to $100\mathrm{\mu m}$. For the $Z^{\prime }$-mediated interaction $V_{AA}$, new upper bounds of the coupling $|g_A^e{g}_A^N|$ are expected within the force range from 10 nm to 1 cm. The new upper bounds for $V_{PP}$ and $V_{AA}$ are both expected to be more than 5 orders of magnitude more stringent than existing constraints at the force range of $1\mathrm{\mu m}$ with the total measurement time of 1 day.

We study the properties of vectorlike fermions that have the same gauge charges as the Standard Model lepton doublets, but opposite lepton number. These antileptons undergo decays mediated by heavier scalar leptoquarks, while the symmetries of this renormalizable model protect the vectorlike fermions and the leptoquarks from standard decays probed so far at colliders. We derive upper limits on the new Yukawa couplings imposed by flavor-changing processes, including $B\to K\nu \overline{\nu }$ and $B_s-{\overline{B}}_s$ mixing, and show that they are compatible with prompt antilepton decays at the LHC for wide parameter ranges. If the new particles couple predominantly to second-generation quarks, then their collider probes involve multiple jets and two taus or neutrinos, and are hampered by large backgrounds. If couplings to third-generation quarks are large, then the collider signals involve top quarks, and can be probed more efficiently at the LHC. Even in that case, both the vectorlike fermion doublet and the leptoquarks remain more elusive than in models with standard decays.

We discuss the leptonic axionlike particle (ALP) portal as a simple scenario that connects observed discrepancies in anomalous magnetic moments to the dark matter relic abundance. In this framework an axionlike particle in the multi-MeV range couples to SM leptons and a dark matter (DM) fermion, with mass above the ALP mass but below 1 GeV. The ALP contributes to $(g-2{)}_{\mu }$ and $(g-2{)}_e$ dominantly through two-loop Barr-Zee diagrams, while the DM abundance is generated by $p$-wave annihilation to ALP pairs. Constraints from beam-dump experiments, colliders, and cosmic microwave background probes are very stringent, and restrict the viable parameter space to a rather narrow region that will be tested in the near future.

We present the light-flavor quark masses and low-energy constants using the $2+1$ flavor full-QCD ensembles with stout smeared-clover fermion action and Symanzik gauge action. Both the fermion and gauge actions are tadpole improved self-consistently. The simulations are performed on 11 ensembles at three lattice spacings $a\in [0.05,0.11]\mathrm{fm}$, four spatial sizes $L\in [2.5,5.1]\mathrm{fm}$, seven pion masses $m_{\pi }\in [135,350]\mathrm{MeV}$, and several values of the strange quark mass. The quark mass is defined through the partially conserved axial current relation and renormalized to $\overline{\mathrm{MS}}(2\mathrm{GeV})$ through the intermediate regularization independent momentum subtraction scheme. The systematic uncertainty of using the symmetric momentum subtraction scheme is also included. Eventually, we predict $m_u=2.45(22)(20)\mathrm{MeV}$, $m_d=4.74(11)(09)\mathrm{MeV}$, and $m_s=98.8(2.9)(4.7)\mathrm{MeV}$ with the systematic uncertainties from lattice spacing determination, continuum extrapolation and renormalization constant included. We also obtain the chiral condensate ${\mathrm{\Sigma }}^{1/3}=268.6(3.6)(0.7)\mathrm{MeV}$ and the pion decay constant $F=86.6(7)(1.4)\mathrm{MeV}$ in the $N_f=2$ chiral limit, and the next-to-leading order low-energy constants ${\ell }_3=2.43(54)(05)$ and ${\ell }_4=4.322(75)(96)$.

We present a lattice QCD calculation of the transversity isovector- and isoscalar-quark parton distribution functions (PDFs) of the proton utilizing a perturbative matching at next-to-leading-order (NLO) accuracy. Additionally, we determine the isovector and isoscalar tensor charges for the proton. In both calculations, the disconnected contributions to the isoscalar matrix elements have been ignored. The calculations are performed using a single ensemble of $N_f=2+1$ highly improved staggered quarks simulated with physical-mass quarks and a lattice spacing of $a=0.076\mathrm{fm}$. The Wilson-clover action, with physical quark masses and smeared gauge links obtained from one iteration of hypercubic smearing, is used in the valence sector. Using the NLO operator product expansion, we extract the lowest four to six Mellin moments and the PDFs via a neural network from the matrix elements in the pseudo-PDF approach. In addition, we calculate the PDFs in the quasi-PDF approach with hybrid-scheme renormalization and the recently developed leading-renormalon resummation technique, at NLO with the resummation of leading small-$x$ logarithms.

The impact of recent LHC top-quark pair production single differential cross section measurements at 13 TeV collision energy on the structure of the proton is explored. In particular, the impact of these high-precision data on the gluon and other parton distribution functions (PDFs) of the proton at intermediate and large partonic momentum fraction $x$ is analyzed. This study extends the CT18 global analysis framework to include these new data. The interplay between top-quark pair and inclusive jet production as well as other processes at the LHC, is studied. In addition, a study of the impact of scale choice on the theory description of the new 13 TeV $t\overline{t}$ measurements is performed.

The directionality information of incoming neutrinos is essential to atmospheric neutrino oscillation analysis since it is directly related to the oscillation baseline length. Large homogeneous liquid scintillator detectors, while offering excellent energy resolution, are traditionally very limited in their capabilities of measuring event directionality. In this paper, we present a novel directionality reconstruction method for atmospheric neutrino events in large homogeneous liquid scintillator detectors based on waveform analysis and machine learning techniques. We demonstrate for the first time that such detectors can achieve good direction resolution and potentially play an important role in future atmospheric neutrino oscillation measurements.

Strong evidence for the Helling-Downs correlation curves have been reported by multiple pulsar timing array (PTA) collaborations in the middle of 2023. In this work, we investigate the graviton mass bounds by analyzing the observational data of the overlap reduction functions from the NANOGrav 15-year data release and CPTA first data release. The results from our data analysis display the state-of-the-art upper limits on the graviton mass at 90% confidence level, namely, $m_g\lesssim 8.6\times {10}^{-24}\mathrm{eV}$ from NANOGrav and $m_g\lesssim 3.8\times {10}^{-23}\mathrm{eV}$ from CPTA. We also study the cosmic-variance limit on the graviton mass bounds, i.e., ${\sigma }_{m_g}^{\mathrm{CV}}=4.8\times {10}^{-24}\mathrm{eV}\times f/(10\mathrm{year}{)}^{-1}$, with $f$ being a typical frequency band of PTA observations. This is equivalent to the cosmic-variance limit on the speed of gravitational waves, i.e., ${\sigma }_{v_g}^{\mathrm{CV}}=0.07c$, with $c$ being the speed of light. Moreover, we discuss potential implications of these results for scenarios of ultralight tensor dark matter.

Black hole horizons in equilibrium and null infinity of asymptotically flat space-times are null 3-manifolds but have very different physical connotations. We first show that they share a large number of geometric properties, making them both weakly isolated horizons. We then use this new unified perspective to unravel the origin of the drastic differences in the physics they contain. Interestingly, the themes are woven together in a manner reminiscent of voices in a fugue.

In contrast to the electromagnetic form factors of the nucleon and nuclei that have been extensively studied in electron scattering, there is no known way to directly measure the gravitational form factors (GFFs), the off-forward hadronic matrix element of the QCD energy-momentum tensor. I suggest exploring the possibility to access the GFFs of the proton and nuclei in conjunction with massive graviton searches at future TeV-scale lepton-ion colliders.

We present a symplectic formulation of the $N=1$ four-dimensional type IIB scalar potential arising from a flux superpotential which has four $S$-dual pairs of fluxes demanded by the $U$-dual completion arguments. Our symplectic formulation presents a very compact and concise way of expressing the generic scalar potential in just a few terms via using a set of symplectic identities along with the so-called “axionic-flux” combinations. We demonstrate the utility of our symplectic master formula by considering an underlying four-dimensional type IIB supergravity model based on a ${\mathbb{T}}^6/({\mathbb{Z}}_2\times {\mathbb{Z}}_2)$ orientifold, in which the scalar potential induced by the $U$-dual flux superpotential results in a total of 76 276 terms involving 128 flux parameters. Given that our symplectic formulation does not need the information about the metric of the internal background, it is applicable to the models beyond the toroidal compactifications such as to those which use orientifolds of the Calabi-Yau threefolds.

We show how flux vacua that differ from each other in flux quanta can be seen as different vacua in a single scalar potential of an enlarged field space, which resolves the separation by thin domain walls. This observation, which is motivated by the anti–de Sitter distance conjecture, allows one to compute distances between different vacua using the usual field-space metric. We verify for explicit examples such as scale-separated IIA flux vacua and the IIB Freund-Rubin vacua that the distance conjecture (for scalar fields) is satisfied and that the asymptotic directions in the enlarged field space are indeed hyperbolic. This enlarged field space contains the tachyon fields on the unstable $\tilde{\mathrm{D}}p$-branes of type II string theory, which can induce the brane charges of the stable D-branes. We suggest that requiring continuous interpolations refines the cobordism conjecture and postdicts the existence of unstable $\tilde{\mathrm{D}}p$-branes.

In this paper we study $U(N)$ colored HOMFLY-PT polynomials of torus links in the double scaling limit (polynomial variable $q\to 1$, $N\to \infty$ keeping $q^N$ fixed). We show that, in this limit, the colored HOMFLY-PT polynomial of any $(L\alpha ,L\beta )$ torus link can be expressed in terms of the colored HOMFLY-PT polynomial of $(L,L)$ torus link. Using the connection between matrix models and the Chern-Simons field theoretic invariants, we show that the colored torus link invariants are uniquely expressed in terms of connected correlation functions of operators in $U(N)$ matrix model. We determine the leading and subleading contribution to some of the correlators at large $N$ from the matrix model approach and find that they match exactly with those obtained from the corresponding colored HOMFLY-PT polynomials.

We investigate the transmission of classical and quantum information between three observers in a general globally hyperbolic spacetime using a quantum scalar field as a communication channel. We build a model for a quantum broadcast channel in which one observer (sender) wishes to transmit (classical and quantum) information to two other observers (receivers). They possess some localized two-level quantum system (a qubit) that can interact with the quantum field in order to prepare an input or receive the output of this channel. The field is supposed to be in an arbitrary quasifree state, the three observers may be in arbitrary states of motion, and no choice of representation of the field canonical commutation relations is made. The interaction of the field and qubits is such that it allows us to obtain the map that describes this channel in a nonperturbative manner. We conclude by analyzing the rates at which information can be transmitted through this channel and by investigating relativistic causality effects on such rates.

A flat 3-brane probing a five-dimensional anti–de Sitter space has the same symmetries and symmetry breaking pattern as one probing a five-dimensional de Sitter space with two time directions. Despite the seemingly different physical setups, we show that the effective field theory of the brane bending mode is identical in both cases. In particular, despite “wrong” signs in the Dirac-Born-Infeld (DBI) action for the two-time de Sitter case, the theories have the same $S$-matrix. This is consistent with the expectation that effective field theories are determined solely by their degrees of freedom and pattern of symmetry breaking, even in the case of spacetime symmetries. We comment further on the equivalence between the Weyl/dilaton and DBI representations of the EFT of broken conformal symmetry.

A reformulation of general relativity inspired by the Belinski-Khalatnikov-Lifshitz conjecture had been introduced by Ashtekar, Henderson, and Sloan which is based on variables closely related to the basic variables of loop quantum gravity, thereby providing a way of classically analyzing singularities that may be carried over to the quantum theory. It is reasonable to expect that these variables are regular at generic spacelike singularities. This has been shown on various examples—particularly, cosmological spacetimes. In this study we extend this analysis to the singularities of gravitational wave collision spacetimes, which are the result of the mutual focusing of the two waves. We focus on two specific examples and explicitly confirm that the said variables are regular at the singularity and can be smoothly continued beyond it.

We apply neural posterior estimation for fast-and-accurate hierarchical Bayesian inference of gravitational wave populations. We use a normalizing flow to estimate directly the population hyper-parameters from a collection of individual source observations. This approach provides complete freedom in event representation, automatic inclusion of selection effects, and (in contrast to likelihood estimation) without the need for stochastic samplers to obtain posterior samples. Since the number of events may be unknown when the network is trained, we split into subpopulation analyses that we later recombine; this allows for fast sequential analyses as additional events are observed. We demonstrate our method on a toy problem of dark siren cosmology, and show that inference takes just a few minutes and scales to $\sim 600$ events before performance degrades. We argue that neural posterior estimation therefore represents a promising avenue for population inference with large numbers of events.

In this paper, we propose a new analog gravity example—a spinning (or Kerr) black hole in an extended fluid model; the latter was derived in an earlier work [A. K. Mitra and S. Ghosh, Divergence anomaly and Schwinger terms: Towards a consistent theory of anomalous classical fluids, Phys. Rev. D 106, L041702 (2022).] by two of the present authors. The fluid model receives Berry curvature contributions and applies to electron dynamics in condensed matter lattice systems in the hydrodynamic limit. We construct the acoustic metric for sonic fluctuations that obey a structurally relativistic wave equation in an effective curved background. In a novel approach of dimensional analysis, we have derived explicit expressions for effective mass and angular momentum per unit mass in the acoustic metric (in terms of fluid parameters), to identify with corresponding parameters of the Kerr metric. The spin is a manifestation of the Berry curvature-induced effective noncommutative structure in the fluid. Finally we put the Kerr black hole analogy in a robust setting by revealing explicitly the presence of horizon and ergoregion for a specific background fluid velocity profile. We also show that near horizon behavior of the phase-space trajectory of a probe particle agrees with Kerr black hole analogy. In a fluid dynamics perspective, the presence of a horizon signifies the wave blocking phenomenon.