The Peccei-Quinn (PQ) mechanism not only acts as an explanation for the absence of strong charge parity ($CP$) violation but also can play a main role in the solution to other open questions in particle physics and cosmology. Here we consider a model that identifies the PQ symmetry as a common thread in the solution to the strong $CP$ problem, the generation of radiative Dirac neutrino masses and the origin of a multicomponent dark sector. Specifically, scotogenic neutrino masses arise at one-loop level with the lightest fermionic mediator field acting as the second dark matter (DM) candidate thanks to the residual $Z_2$ symmetry resulting from the PQ symmetry breaking. We perform a phenomenological analysis addressing the constraints coming from the direct searches of DM, neutrino oscillation data and charged lepton flavor violating (LFV) processes. We find that the model can be partially probed in future facilities searching for weakly interacting massive particles and axions, and accommodates rates for rare leptonic decays that are within the expected sensitivity of upcoming LFV experiments.

We study the two scalar leptoquarks capable of generating chirally enhanced, sign-dependent contributions to lepton magnetic dipole moments (MDMs) and electric dipole moments (EDMs), $R_2\sim (\mathbf{3},\mathbf{2},7/6)$ and $S_1\sim (\mathbf{3},\mathbf{1},-1/3)$. We consider the case in which the electron and muon sectors are decoupled, and leptoquark couplings are assigned complex values. Adopting the coupling ansatz that the electron dipole operator is generated by charm-containing loops, and muon dipole operator by top-containing loops, we find that both minimal leptoquark models remain viable solutions for reconciling anomalies in the muon and electron MDMs, accounting for either of the two current (disparate) electron MDM results from Cs and Rb interferometry experiments. We also examine the correlated corrections to the muon and electron masses generated by these models, and argue that to minimize fine-tuning this introduces an upper bound on viable leptoquark ($\varphi$) masses, $m_{\varphi }<\mathcal{O}(4)\mathrm{TeV}$. Similar arguments allow us to make a prediction for the upper bound of the muon EDM generated by these models, $|d_{\mu }|<\mathcal{O}({10}^{-22})e\mathrm{cm}$, which could be within reach of upcoming experimental programs, including Muon $g-2$ at Fermilab (FNAL), and muEDM at Paul Scherrer Institut (PSI).

We develop a framework for computing light dark matter direct detection rates through single phonon and magnon excitations via general effective operators. Our work generalizes previous calculations focused on spin-independent interactions involving the total nucleon and electron numbers $N$ (the usual route to excite phonons) and spin-dependent interactions involving the total electron spin $\mathit{S}$ (the usual route to excite magnons), leading us to identify new responses involving the orbital angular momenta $\mathit{L}$, as well as spin-orbit couplings $\mathit{L}\otimes \mathit{S}$ in the target. All four types of responses can excite phonons, while couplings to electron’s $\mathit{S}$ and $\mathit{L}$ can also excite magnons. We apply the effective field theory approach to a set of well-motivated relativistic benchmark models, including (pseudo) scalar mediated interactions, and models where dark matter interacts via a multipole moment, such as a dark electric dipole, magnetic dipole or anapole moment. We find that couplings to pointlike degrees of freedom $N$ and $\mathit{S}$ often dominate dark matter detection rates, implying that exotic materials with orbital $\mathit{L}$ order or large spin-orbit couplings $\mathit{L}\otimes \mathit{S}$ are not necessary to have strong reach to a broad class of DM models. We highlight that phonon based crystal experiments in active R&D (such as SPICE) will probe light dark matter models well beyond those having a simple spin-independent interaction, including e.g., models with dipole and anapole interactions. Lastly, we make publicly available a code, $\mathsf{PhonoDark}$, which computes single phonon production rates in a wide variety of materials with the effective field theory framework.

The ’t Hooft-Veneziano limit of various $U(N)$ and $SU(N)$ Polyakov loop models is constructed at finite temperature and nonzero baryon chemical potential. In this paper we calculate the free energy, its derivatives, the Polyakov loop expectation values and the baryon density. The phase diagram is described in detail.

The use of light front coordinates allows a fully relativistic description of a hadron’s spatial densities to be obtained. These densities must be two-dimensional and transverse to a chosen spatial direction. We explore their relationship to the three-dimensional, nonrelativistic densities, with a focus on densities associated with the energy-momentum tensor. The two-dimensional nonrelativistic densities can be obtained from the light front densities through a nonrelativistic limit, and can subsequently be transformed into three-dimensional nonrelativistic densities through an inverse Abel transform. However, this operation is not invertible, and moreover the application of the inverse Abel transform to the light front densities does not produce a physically meaningful result. We additionally find that the Abel transforms of so-called Breit-frame densities generally differ significantly from the light front densities. Numerical examples are provided to illustrate the various differences between the light front, Breit frame, and nonrelativistic treatment of densities.

Deep inelastic scattering (DIS) samples a part of the wave function of a hadron in the vicinity of the light cone. Lipatov constructed a spin chain which describes the amplitude of DIS in leading logarithmic approximation. Kharzeev and Levin proposed the entanglement entropy as an observable in DIS [Phys. Rev. D 95, 114008 (2017)], and suggested a relation between the entanglement entropy and parton distributions. Here we represent the DIS process as a local quench in Lipatov’s spin chain and study the time evolution of the produced entanglement entropy. We show that the resulting entanglement entropy depends on time logarithmically, $\mathcal{S}(t)=1/3\ln (t/\tau )$ with $\tau =1/m$ for $1/m\le t\le (mx{)}^{-1}$, where $m$ is the proton mass and $x$ is the Bjorken $x$. The central charge $c$ of Lipatov’s spin chain is determined here to be $c=1$; using the proposed relation between the entanglement entropy and parton distributions, this corresponds to the gluon structure function growing at small $x$ as $xG(x)\sim 1/x^{1/3}$.

Expressions for neutrino oscillations contain a high degree of symmetry, but typical forms for the oscillation probabilities mask these symmetries of the oscillation parameters. We elucidate the $2^7$ parameter symmetries of the vacuum parameters and draw connections to the choice of definitions of the parameters as well as interesting degeneracies. We also show that in the presence of matter an additional set of $2^7$ parameter symmetries of the matter parameters exists. Due to the complexity of the exact expressions for neutrino oscillations in matter, numerous approximations have been developed; we show that under certain assumptions approximate expressions have at most $2^6$ additional parameter symmetries of the matter parameters. We also include one parameter symmetry related to the large mixing angle (LMA)-dark degeneracy that holds under the assumption of $CPT$ invariance; this adds one additional factor of 2 to all of the above cases. Explicit, nontrivial examples are given of how physical observables in neutrino oscillations, such as the probabilities, $CP$ violation, the position of the solar and atmospheric resonance, and the effective $\mathrm{\Delta }{m}^2$’s for disappearance probabilities, are invariant under all of the above symmetries. We investigate which of these parameter symmetries apply to numerous approximate expressions in the literature and show that a more careful consideration of symmetries improves the precision of approximations.

In this work we obtain the analytical expressions for the boundaries of the charged current quasielastic (CCQE) double differential cross section in terms of dimensionless energy and momentum transfers, for the Relativistic Fermi Gas (RFG) and the Superscaling approach with relativistic effective mass (SuSAM*) models, within the scaling formalism. In addition, we show that this double differential cross section in the scaling formalism has very good properties to be implemented in the Monte Carlo (MC) neutrino event generators, particularly because its peak is almost flat with the (anti)neutrino energy. This makes it especially well suited for the event generation by the acceptance-rejection method usually used in the neutrino generators. Finally, we analyze the total CCQE cross section $\sigma (E_{\nu })$ for both models and attribute the enhancement observed in the SuSAM* total cross section to the high-momentum components which are present, in a phenomenological way, in its scaling function, while these are absent in the RFG model.

Based on reasonable assumptions, we propose a new expression for Lloyd’s bound, which confines the complexity growth of charged black holes. We then revisit holographic complexity for charged black branes in the presence of a finite cutoff. Using the proposed Lloyd’s bound we find a relation between the UV and the behind the horizon cutoff. This is found to be consistent with the factorization of the partition function at leading order in large $N$. We argue that the result may be thought of as a holographic realization of strong cosmic censorship.

In general relativity (GR), gravitational waves (GWs) propagate the well-known plus and cross tensorial polarization modes, which are the signature of a massless spin-2 field. However, diffraction of GWs caused by intervening objects along the line of sight can cause the apparent rise of additional polarizations due to GW-curvature interactions. In this paper, we continue the analysis by two of the authors of the present article, on lensing of gravitational waves beyond geometric optics. In particular, we calculate the lensing effect caused by a pointlike lens in the regime where its Schwarzschild radius $R_s$ is much smaller than the wavelength $\lambda$ of the signal, itself smaller than the impact parameter $b$. In this case, the curvature of spacetime induces distortions in the polarization of the wave such that diffraction effects may be misinterpreted as effective scalar and vector polarizations. We find that the amplitude of these apparent nontensor polarizations is suppressed by a factor $R_s\lambda /b^2$ with respect to the amplitude of the tensor modes. We estimate the probability to develop these extra polarization modes for a nearly monochromatic GW in the pulsar timing arrays band traveling through a distribution of galaxies.

In the present paper, we compute the Euclidean action of a generic system consisting of $N$ arbitrary Kerr-Newman black holes located on the symmetry axis and separated from each other by massless struts. This allows us to introduce for the first time the notion of “Hawking average temperature” $\widehat{T}$ of the multi-black-hole system via the condition of vanishing the entire set of terms involving the singular horizons due to periodic time, and the resulting formula for this temperature contains solely the surface gravities ${\kappa }_i$ and horizon areas $A_i^H$ of the black hole constituents. We also show that the corresponding expression for the free energy of the system defined by $\widehat{T}$ is consistent with the first law of thermodynamics and Smarr mass relations.

The class of scalar-tensor theories with the scalar field coupling to the Gauss-Bonnet invariant has drawn great interest since solutions of spontaneous scalarization were found for black holes in these theories. We contribute to the existing literature a detailed study of the spontaneously scalarized neutron stars (NSs) in a typical theory where the coupling function of the scalar field takes the quadratic form and the scalar field is massive. The investigation here includes the spherical solutions of the NSs as well as their perturbative properties, namely the tidal deformability and the moment of inertia, treated in a unified and extendable way under the framework of spherical decomposition. We find that while the mass, the radius, and the moment of inertia of the spontaneously scalarized NSs show very moderate deviations from those of the NSs in general relativity (GR), the tidal deformability exhibits significant differences between the solutions in GR and the solutions of spontaneous scalarization for certain values of the parameters in the scalar-Gauss-Bonnet theory. As a result, the celebrated universal relation between the moment of inertia and the tidal deformability of neutron stars breaks down. With the mass and the tidal deformability of NSs attainable in the gravitational waves from binary NS mergers, the radius measurable using the x-ray satellites, and the moment of inertia accessible via the high-precision pulsar timing techniques, future multimessenger observations can be contrasted with the theoretical results and provide us necessary information for building up theories beyond GR.

We solve Einstein’s equations for slowly rotating gravitational condensate stars (gravastars) up to second order in the rotation by expanding about the spherically symmetric gravastar with de Sitter interior and Schwarzschild exterior matched at their common horizon. Requiring that the perturbations are finite on the null surface reduces the exterior geometry to that of a Kerr black hole, implying that a slowly rotating gravastar cannot be distinguished from a Kerr black hole by any measurement or observation restricted to the macroscopic spacetime exterior to the horizon. We determine the interior solution, the surface stress tensor, and the Komar mass and angular momentum localized on the slowly rotating horizon surface. With the interior equation of state fixed at $p=-\rho$, finite junction conditions on the null horizon surface necessarily lead to an interior solution with a singular core, where the perturbative expansion breaks down. Comparison to other models and implications for more rapidly rotating gravastars are briefly discussed.

The general form of the surface stress tensor of an infinitesimally thin shell located on a rotating null horizon is derived, when different interior and exterior geometries are joined there. Although the induced metric on the surface must be the same approached from either side, the first derivatives of the metric need not be. Such discontinuities lead to a Dirac $\delta$-distribution in the Einstein tensor localized on the horizon. For a general stationary axisymmetric geometry the surface stress tensor can be expressed in terms of two geometric invariants that characterize the surface, namely the discontinuities [$\kappa$] and $[\mathcal{J}]$ of the surface gravity $\kappa$ and angular momentum density $\mathcal{J}$. The Komar energy and angular momentum are given in coordinates adapted to the Killing symmetries, and the surface contributions to each determined in terms of [$\kappa$] and $[\mathcal{J}]$. Guided by these, a simple modification of the original Israel junction conditions is verified directly from the Einstein tensor density to give the correct finite result for the surface stress, when the normal $\mathit{n}$ to the surface is allowed to tend continuously to a null vector. The relation to Israel’s original junction conditions, which fail on null surfaces, is given. The modified junction conditions are suitable to the matching of a rotating “black hole” exterior to any interior geometry joined at the Kerr null horizon surface, even when the surface normal is itself discontinuous and the Barrabès-Israel formalism is also inapplicable. This joining on a rotating null horizon is purely of the matter shell type and does not contain a propagating gravitational shock wave.

The detection of $\sim 50$ coalescing compact binaries with the Advanced LIGO and Virgo detectors has allowed us to test general relativity, constrain merger rates, and look for evidence of tidal effects, compact object spins, higher waveform modes, and black hole ringdowns. An effect that has not yet been confidently detected is binary eccentricity, which might be present in a small fraction of binaries formed dynamically. Here we discuss general limits on eccentricity that can, in-principle, be placed on all types of compact object binaries by a detector operating at the design sensitivity of Advanced LIGO. Using a post-Newtonian model for gravitational-wave phasing valid in the small eccentricity regime, we assess the relative measurement error for eccentricity for a variety of spinning and nonspinning binaries. Errors and correlations involving the mass and spin parameters are also investigated. We find that decreasing the low frequency limit of a detector’s observational frequency band is one of the key design factors for increasing the odds of measuring binary eccentricity. We also introduce and analytically explore the eccentric chirp mass parameter, which replaces the chirp mass as the key measurable parameter combination in eccentric gravitational waveform models. The eccentric chirp mass parameter explains a degeneracy between the chirp mass and the eccentricity. This degeneracy leads to a bias in the standard chirp mass parameter. We also investigate the systematic parameter bias that arises when eccentric systems are recovered using circular waveform templates. We use both Fisher matrix and Bayesian-inference-based Markov Chain Monte Carlo (MCMC) methods to investigate these parameter estimation issues, and we find good agreement between the two approaches (for both statistical and systematic errors) in the appropriate signal-to-noise ratio regime. This study helps to quantify how effectively one can use eccentricity measurements as a probe of binary formation channels.

We study an impact of self-interacting bosonic dark matter (DM) on various observable properties of neutron stars (NSs). The analysis is performed for asymmetric DM with masses from few MeV to GeV, the self-coupling constant of order $\mathcal{O}(1)$ and various DM fractions. Allowing a mixture between DM and baryonic matter, the formation of a dense DM core or an extended dark halo has been explored. We find that both distribution regimes crucially depend on the mass and fraction of DM for sub-GeV boson masses in the strong coupling regime. From the combined analysis of the mass-radius relation and the tidal deformability of compact stars including bosonic DM, we set a stringent constraint on DM fraction. We conclude that observations of $2M_{\odot }$ NSs together with ${\mathrm{\Lambda }}_{1.4}\le 580$ constraint, set by LIGO/Virgo Collaboration, favor sub-GeV DM particles with low fractions below $\sim 5\%$.

We discuss the impact of the new LHCb fixed-target $p+{}^4\mathrm{He}$ data for $D^0/{\overline{D}}^0$ production on the intrinsic $c\overline{c}$ component in the nucleon wave function. Within the scenario presented here neither the traditional gluon-gluon fusion or quark-antiquark annihilation mechanisms calculated in the $k_T$-factorization approach nor their counterparts from the collinear next-to-leading order collinear framework are sufficient to describe the transverse momentum and rapidity distributions of $D^0/{\overline{D}}^0$ mesons. First the $c\overline{c}$-pair production within the standard frameworks is considered. Here a crucial role of the $c\to D$ hadronization effects at low energies and low transverse momenta is found and discussed, which was not analyzed in previous studies. A contribution related to intrinsic $c\overline{c}$ component in the nucleon wave function is included in addition. Two models of the symmetric ($c(x)=\overline{c}(x)$) intrinsic charm (IC) component are considered. The intrinsic charm $g^{*}c\to gc$ (or $g^{*}\overline{c}\to g\overline{c}$) contribution needs to be regularized in order to obtain a suppression of the minijet $p_T$ spectrum present in the phenomenological minijet model, commonly used in Monte Carlo generators. We show that in our model the regularization parameter can be obtained from the fit to the LHCb fixed-target data under consideration here. We discuss uncertainties of our calculations (scale, charm quark mass, fragmentation function) as well as set limits on the IC probability. According to our model the intrinsic charm probability $P_{\mathrm{IC}}=1.65\%$ allows to significantly improve description of the LHCb data but the number is rather uncertain.

We present high-accuracy QCD predictions for the transverse-momentum ($q_T$) distribution and fiducial cross sections of Drell–Yan lepton pairs produced in hadronic collisions. At small values of $q_T$ we resum to all perturbative orders the logarithmically enhanced contributions up to next-to-next-to-next-to-leading logarithmic (${\mathrm{N}}^3\mathrm{LL}$) accuracy, including all the next-to-next-to-next-to-leading order (${\mathrm{N}}^3\mathrm{LO}$) [i.e., $\mathcal{O}({\alpha }_S^3)$] terms. Our resummed calculation has been implemented in the public numerical program DYTurbo, which produces fast and precise predictions with the full dependence on the final-state lepton kinematics. We consistently combine our resummed results with the known $\mathcal{O}({\alpha }_S^3)$ fixed-order predictions at large values of $q_T$ thus also obtaining full ${\mathrm{N}}^3\mathrm{LO}$ accuracy for fiducial cross sections. We show numerical results at LHC energies discussing the reduction of the perturbative uncertainty with respect to lower-order calculations.

We obtain the exact solutions to the field equations for massless scalar and massless spinor fields on quantized two-dimensional anti–de Sitter space. We then apply the $\mathrm{AdS}/\mathrm{CFT}$ correspondence principle to get exact answers for the two-point correlation functions of the associated operators on the boundary. The results support the conclusion that conformal symmetry on the boundary is not spoiled by quantization of the bulk. Moreover, quantization of the bulk has no effect on the spinor two-point correlation function, while it induces an overall rescaling in the scalar two-point correlation function.

The 4D four-point scattering amplitude of massless scalars via a massive exchange is expressed in a basis of conformal primary particle wave functions. This celestial amplitude is expanded in a basis of 2D conformal partial waves on the unitary principal series, and then rewritten as a sum over 2D conformal blocks via contour deformation. The conformal blocks include intermediate exchanges of spinning light-ray states, as well as scalar states with positive integer conformal weights. The conformal block prefactors are found as expected to be quadratic in the celestial operator product expansion coefficients.