We develop a nonperturbative analysis of the electroproduction of heavy vector mesons ($\varphi$, $J/\mathrm{\Psi }$) from threshold to high energy. We use the holographic construction with bulk confinement enforced through a soft wall. Using Witten diagrams, we evaluate the pertinent cross sections for heavy vector mesons ($\varphi$, $J/\mathrm{\Psi }$) production and study their dependence on both the incoming virtual photon polarization as well as the outgoing polarization of the heavy meson. Our results for $J/\mathrm{\Psi }$ electroproduction compares well with the available HERA data at low and intermediate $Q^2$, and for a wide range of momentum transfer. We also predict the quasi-electroproduction of $J/\mathrm{\Psi }$ near threshold.

We derive constraints on scalar field theories coupled to gravity by using recently developed positivity bounds in the presence of gravity. It is found that a canonically normalized real scalar cannot have an arbitrarily flat potential unless some new physics enters well below the Planck scale. An upper bound on the scale of new physics is determined by loop corrections to the self-energy. Our result provides a swampland condition for scalar potentials.

The Palatini gravitational action is enlarged by an arbitrary function $f(\mathit{X})$ of the determinants of the Ricci tensor and the metric, $\mathit{X}=|\mathbf{det}.R|/|\mathbf{det}.g|$. The resulting Ricci-determinant theory exhibits novel deviations from general relativity. We study a particular realization where the extension is characterized by the square-root of the Ricci determinant, $f(\mathit{X})={\lambda }_{\mathrm{Edd}}\sqrt{\mathit{X}}$, which corresponds to the famous Eddington action. We analyze the obtained equations for perfect fluid source and show that the affine connection can be solved in terms of the energy density and pressure of the fluid through an obtained disformal metric. As an application, we derive the hydrostatic equilibrium equations for relativistic stars and inspect the significant effects induced by the square-root of the Ricci tensor. We find that an upper bound on ${\lambda }_{\text{Edd}}$, at which deviations from the predictions of general relativity on neutron stars become prominent, corresponds to the hierarchy between the Planck and the vacuum mass scales. The Ricci-determinant gravity that we propose here is expected to have interesting implications in other cosmological domains.

The existence of black holes is one of the key predictions of general relativity (GR) and therefore a basic consistency test for modified theories of gravity. In the case of spherical symmetry in GR the existence of an apparent horizon and its regularity is consistent with only two distinct classes of physical black holes. Here we derive constraints that any self-consistent modified theory of gravity must satisfy to be compatible with their existence. We analyze their properties and illustrate characteristic features using the Starobinsky model. Both of the GR solutions can be regarded as zeroth-order terms in perturbative solutions of this model. We also show how to construct nonperturbative solutions without a well-defined GR limit.

Exotic electromagnetic energy injection in the early Universe may alter cosmological recombination, and ultimately cosmic microwave background (CMB) anisotropies. Moreover, if energy injection is inhomogeneous, it may induce a spatially varying ionization fraction, and non-Gaussianity in the CMB. The observability of these signals, however, is contingent upon how far the injected particles propagate and deposit their energy into the primordial plasma, relative to the characteristic scale of energy injection fluctuations. In this study we inspect the spatial properties of energy deposition and perturbed recombination resulting from an inhomogeneous energy injection of sub-10 MeV photons, relevant to accreting primordial black holes (PBHs). We develop a novel Monte Carlo radiation transport code accounting for all relevant photon interactions in this energy range, and including secondary electron energy deposition efficiency through a new analytic approximation. For a specified injected photon spectrum, the code outputs an injection-to-deposition Green’s function depending on time and distance from the injection point. Combining this output with a linearized solution of the perturbed recombination problem, we derive time- and scale-dependent deposition-to-ionization Green’s functions. We apply this general framework to accreting PBHs, whose luminosity is strongly spatially modulated by supersonic relative velocities between cold dark matter and baryons. We find that the resulting spatial fluctuations of the free-electron fraction are of the same magnitude as its mean deviation from standard recombination, from which current CMB power spectra constraints are derived. This work suggests that the sensitivity to accreting PBHs might be substantially improved by propagating these inhomogeneities to CMB anisotropy power spectra and non-Gaussian statistics, which we study in subsequent papers.

We delineate the quark-hadron continuity by constructing QCD equations of state for neutron star dynamics, covering the wide range of charge chemical potential (${\mu }_Q$) and temperatures ($T$). Based on the nuclear-2SC continuity scenario, we match equations of state for nuclear and two-flavor color-superconducting (2SC) quark matter, where the matching baryon density is $n_B\simeq 1.5n_0$ ($n_0\simeq 0.16{\mathrm{fm}}^{-3}$: nuclear saturation density). The effective vector and diquark couplings in a quark matter model evolve as functions of $n_B$ or ($n_B,{\mu }_Q,T$), whose low density values are constrained by the nuclear matter properties and neutron star radii, with the high density behavior by the two solar mass ($2M_{\odot }$) constraint. With couplings dependent on $n_B$, we examined how smooth the nuclear-2SC continuity can be and found problems in matching nuclear and 2SC entropies at low temperatures; they differ unless the baryon Fermi velocity significantly increases to match with the quark’s, or the 2SC matter allows low energy collective modes whose velocities are as low as the baryon’s. This implies that the realization of the nuclear-2SC continuity, if possible, demands additional ingredients to the conventional nuclear and 2SC descriptions. To proceed with the continuity scenario, we enforce smooth matching by making the couplings ($n_B,{\mu }_Q,T$) dependent. In effect, this adds phenomenological contributions which we call “X” to emphasize our ignorance on the practical description. After the phenomenological matching, we take the rest as our predictions. The 2SC and color-flavor-locked (CFL) phases computed with these evolving couplings are called 2SCX and CFLX. The CFLX appears around $n_B\simeq 2–4n_0$ and, in contrast to the conventional CFL, has non-negligible dependence on $({\mu }_Q,T)$. To examine the astrophysical consequences of our modeling, we add charged leptons and neutrinos, and study the composition of matter for lepton fractions relevant for protoneutron stars and neutron star mergers. The abundance of neutrinos and thermal effects reduce the strangeness fraction and stiffen equations of state. For a neutrino trapped neutron star at $T\simeq 30\mathrm{MeV}$ with a lepton fraction $Y_L\simeq 0.05$, the mass is larger than its cold static counterpart by $\sim 0.1M_{\odot }$.

Neutron star tidal deformability extracted from gravitational wave data provides a novel probe to the interior neutron star structures and the associated nuclear equation of state (EOS). Instead of the popular composition of nucleons and leptons in neutron stars, we include hyperons and examine the role of hyperons in the tidal deformability and its impact on the symmetry energy in a relativistic mean-field approach with the density-dependent parametrizations. The hyperons are found to have a significant impact on the deformability, correlated sensitively with the onset density and fraction of hyperons in neutron star matter. A moderately lower onset density of hyperons can yield considerable modification to the tidal deformability and shift its inference on the nuclear EOS. The future measurements of the tidal deformability at multifiducial star masses are anticipated to lift the degeneracy between the contributions from the hyperon component and symmetry energy.

Searches for gravitational waves crucially depend on exact signal processing of noisy strain data from gravitational wave detectors, which are known to exhibit significant nonstationary and non-Gaussian behavior. In this paper, we study two distinct effects in the LIGO/Virgo data that reduce the sensitivity of searches: first, variations in the noise power spectral density (PSD) on timescales of more than a few seconds; and second, loud and abrupt transient “glitches” of terrestrial or instrumental origin. We derive a simple procedure to correct, at first order, the effect of the variation in the PSD on the search background. Given the knowledge of the existence of localized glitches, in particular segments of data, we also develop a method to insulate statistical inference from these glitches, so as to cleanly excise them without affecting the search background in neighboring seconds. We show the importance of applying these methods on the publicly available LIGO data and estimate an increase in the detection volume of at least 15% from the PSD-drift correction alone, due to the improved background distribution.

Recently, the radius of neutron star (NS) PSR $\mathrm{J}0740+6620$ was measured by Neutron Star Interior Composition Explorer (NICER), and an updated measurement of neutron skin thickness of ${}^{208}\mathrm{Pb}$ ($R_{\mathrm{skin}}^{208}$) was reported by the PREX-II experiment. These new measurements can help us better understand the unknown equation of state (EOS) of dense matter. In this work, we adopt a hybrid parameterization method, which incorporates the nuclear empirical parameterization and some widely used phenomenological parameterizations, to analyze the results of nuclear experiments and astrophysical observations. With the joint Bayesian analysis of GW170817, PSR $\mathrm{J}0030+0451$, and PSR $\mathrm{J}0740+6620$, the parameters that characterize the ultradense matter EOS are constrained. We find that the slope parameter $L$ is approximately constrained to ${70}_{-18}^{+21}\mathrm{MeV}$, which predicts $R_{\mathrm{skin}}^{208}=0.204_{-0.026}^{+0.030}\mathrm{fm}$ by using the universal relation between $R_{\mathrm{skin}}^{208}$ and $L$. The bulk properties of canonical $1.4M_{\odot }$ NS (e.g., $R_{1.4}$ and ${\mathrm{\Lambda }}_{1.4}$) as well as the pressure ($P_{2{\rho }_{\mathrm{sat}}}$) at two times the nuclear saturation density are well constrained by the data; i.e., $R_{1.4}$, ${\mathrm{\Lambda }}_{1.4}$, and $P_{2{\rho }_{\mathrm{sat}}}$ are approximately constrained to $12.3\pm 0.7\mathrm{km}$, ${330}_{-100}^{+140}$, and ${4.1}_{-1.2}^{+1.5}\times {10}^{34}\mathrm{dyn}{\mathrm{cm}}^{-2}$, respectively. Besides, we find that the Bayes evidences of the hybrid star and normal NS assumptions are comparable, which indicates that current observation data are compatible with quarkyonic matter existing in the core of massive star. Finally, in the case of normal NS assumption, we obtain a constraint for the maximum mass of nonrotating NS $M_{\mathrm{TOV}}=2.30_{-0.18}^{+0.30}{M}_{\odot }$. Based on this result and the current observational and theoretical knowledge about the NS population and its EOS, we find that a binary black hole merger scenario for GW190814 is more plausible. All of the uncertainties reported above are for 68.3% credible levels.

Knowledge of the shape of the mass spectrum of compact objects can be used to help break the degeneracy between the mass and redshift of the gravitational wave (GW) sources and thus can be used to infer cosmological parameters in the absence of redshift measurements obtained from electromagnetic observations. In this paper, we study extensively different aspects of this approach, including its computational limits and achievable accuracy. Focusing on ground-based detectors with current and future sensitivities, we first perform the analysis of an extensive set of simulated data using a hierarchical Bayesian scheme that jointly fits the source population and cosmological parameters. We consider a population model (power-law plus Gaussian) which exhibits characteristic scales (extremes of the mass spectrum, presence of an accumulation point modeled by a Gaussian peak) that allow an indirect estimate of the source redshift. Our analysis of this catalog highlights and quantifies the tight interplay between source population and cosmological parameters, as well as the influence of initial assumptions (whether formulated on the source or cosmological parameters). We then validate our results by an “end-to-end” analysis using simulated GW $h(t)$ data and posterior samples generated from Bayesian samplers used for GW parameter estimation, thus mirroring the analysis chain used for observational data for the first time in literature. Our results then lead us to re-examine the estimation of $H_0$ obtained with GWTC-1 in Abbott et al. [LIGO Scientific, Virgo Collaborations, Astrophys. J. 909, 218 (2021)], and we show explicitly how population assumptions impact the final $H_0$ result. Together, our results underline the importance of inferring source population and cosmological parameters simultaneously (and not separately as is often assumed). The only exception, as we discuss, is if an electromagnetic counterpart was to be observed for all the BBH events; then, the population assumptions have less impact on the estimation of cosmological parameters.

In quantum electrodynamics with charged fermions, a background electric field is the source of the chiral anomaly which creates a chirally imbalanced state of fermions. This chiral state is realized through the production of entangled pairs of right-moving fermions and left-moving antifermions (or vice versa, depending on the orientation of the electric field). Here we show that the statistical Gibbs entropy associated with these pairs is equal to the entropy of entanglement between the right-moving particles and left-moving antiparticles. We then derive an asymptotic expansion for the entanglement entropy in terms of the cumulants of the multiplicity distribution of produced particles and explain how to re-sum this asymptotic expansion. Finally, we study the time dependence of the entanglement entropy in a specific time-dependent pulsed background electric field, the so-called “Sauter pulse”, and illustrate how our resummation method works in this specific case. We also find that short pulses (such as the ones created by high energy collisions) result in an approximately thermal distribution for the produced particles.

Whether one is interested in accessing the excited spectrum of hadrons or testing the standard model of particle physics, electroweak transition processes involving multihadron channels in the final state play an important role in a variety of experiments. Presently the primary theoretical tool with which one can study such reactions is lattice QCD, which is defined in a finite spacetime volume. In this work, we investigate the feasibility of implementing existing finite-volume formalism in realistic lattice QCD calculation of reactions in which a stable hadron can transition to one of several two-hadron channels under the action of an external current. We provide a conceptual description of the coupled-channel transition formalism, a practical road map for carrying out a calculation, and an illustration of the approach using synthetic data for two nontrivial resonant toy models. The results provide a proof of principle that such reactions can indeed be constrained using modern-day lattice QCD calculations, motivating explicit computation in the near future.

Large momentum effective field theory (LaMET) enables the extraction of parton distribution functions (PDF’s) directly on a Euclidean lattice through a factorization theorem that relates the computed quasi-PDF’s to PDF’s. We apply chiral perturbation theory (ChPT) to LaMET to further separate soft scales, such as light quark masses and lattice size, to obtain leading model independent extrapolation formulas for extrapolations to physical quark masses and infinite volume. We find that the finite volume effect is reduced when the nucleon carries a finite momentum. For nucleon momentum greater than 1 GeV and the lattice size $L$ and pion mass $m_{\pi }$ satisfying $m_{\pi }L\ge 3$, the finite volume effect is less than 1% and is negligible for the current precision of lattice computations. This can be interpreted as a Lorentz contraction of the nucleon size in the z-direction which makes the lattice size effectively larger in that direction. We also find that the quark mass dependence in the infinite volume limit computed with nonzero nucleon momentum reproduces the previous result computed at zero momentum, as expected. Our approach can be generalized to other parton observables in LaMET straight forwardly.

We study the effects of pion and sigma meson backcoupling on the chiral order parameters and the QCD phase diagram and determine their effect on the location of the chiral critical endpoint. To this end, we solve a coupled set of truncated Dyson-Schwinger equations for Landau gauge quark and gluon propagators with $N_{\mathrm{f}}=2+1$ dynamical quark flavors and explicitly backcoupled mesons. The corresponding meson bound-state properties and the quark-meson Bethe-Salpeter vertices are obtained from their homogeneous Bethe-Salpeter equation. We find chiral-restoration effects of the pion and/or sigma meson backcoupling and observe a (small) shift of the critical endpoint towards smaller chemical potentials. The curvature of the chiral crossover line decreases. Our results indicate that the location of the critical endpoint in the phase diagram is mainly determined by the microscopic degrees of freedom of QCD (in contrast to its critical properties).

We study the contribution from double parton scattering (DPS) to four-jet production at the LHC, both at the leading order accuracy and after incorporating the effects of QCD radiation. Apart from DPS, we also include and discuss the contribution from single parton scattering (SPS). We find that the QCD radiation impacts theoretical predictions significantly, with DPS contributions more affected than SPS contributions. We also examine a number of observables in regard to their effectiveness for discrimination between DPS and SPS events and propose sets of kinematical cuts to improve the prospects of measuring DPS in four-jet production.

A search for $CP$ violation in charmless three-body ${\mathrm{\Xi }}_b^{-}\to p{K}^{-}{K}^{-}$ decays is performed using $pp$ collision data recorded with the LHCb detector, corresponding to integrated luminosities of $1{\mathrm{fb}}^{-1}$ at a center-of-mass energy $\sqrt{s}=7\mathrm{TeV}$, $2{\mathrm{fb}}^{-1}$ at $\sqrt{s}=8\mathrm{TeV}$ and $2{\mathrm{fb}}^{-1}$ at $\sqrt{s}=13\mathrm{TeV}$. A good description of the phase-space distribution is obtained with an amplitude model containing contributions from $\mathrm{\Sigma }(1385)$, $\mathrm{\Lambda }(1405)$, $\mathrm{\Lambda }(1520)$, $\mathrm{\Lambda }(1670)$, $\mathrm{\Sigma }(1775)$ and $\mathrm{\Sigma }(1915)$ resonances. The model allows for $CP$ -violation effects, which are found to be consistent with zero. The branching fractions of ${\mathrm{\Xi }}_b^{-}\to \mathrm{\Sigma }(1385)K^{-}$, ${\mathrm{\Xi }}_b^{-}\to \mathrm{\Lambda }(1405)K^{-}$, ${\mathrm{\Xi }}_b^{-}\to \mathrm{\Lambda }(1520)K^{-}$, ${\mathrm{\Xi }}_b^{-}\to \mathrm{\Lambda }(1670)K^{-}$, ${\mathrm{\Xi }}_b^{-}\to \mathrm{\Sigma }(1775)K^{-}$ and ${\mathrm{\Xi }}_b^{-}\to \mathrm{\Sigma }(1915)K^{-}$ decays are also reported. In addition, an upper limit is placed on the product of ratios of ${\mathrm{\Omega }}_b^{-}$ and ${\mathrm{\Xi }}_b^{-}$ fragmentation fractions and the ${\mathrm{\Omega }}_b^{-}\to p{K}^{-}{K}^{-}$ and ${\mathrm{\Xi }}_b^{-}\to p{K}^{-}{K}^{-}$ branching fractions.

We describe a systematic framework for finding the conservative potential of compact binary systems with spin based on scattering amplitudes of particles of arbitrary spin and effective field theory. An arbitrary-spin formalism is generally required in the classical limit. By matching the tree and one-loop amplitudes of four spinning particles with those of a suitably chosen effective field theory, we obtain the ${\mathrm{spin}}_1\text{−}{\mathrm{spin}}_2$ terms of a two-body effective Hamiltonian through $\mathcal{O}(G^2)$ and valid to all orders in velocity. Solving Hamilton’s equations yields the impulse and spin changes of the individual bodies. We write them in a surprisingly compact form as appropriate derivatives of the eikonal phase obtained from the amplitude. It seems likely this structure persists to higher orders. We also point out various double-copy relations for general spin.

We present the fastemriwaveforms (FEW) package, a collection of tools to build and analyze extreme mass ratio inspiral (EMRI) waveforms. Here, we expand on [A. J. K. Chua et al., Phys. Rev. Lett. 126, 051102 (2021).] that introduced the first fast and accurate fully-relativistic EMRI waveform template model. We discuss the construction of the overall framework; constituent modules; and the general methods used to accelerate EMRI waveforms. Because the fully relativistic FEW model waveforms are for now limited to eccentric orbits in the Schwarzschild spacetime, we also introduce an improved augmented analytic kludge (AAK) model that describes generic Kerr inspirals. Both waveform models can be accelerated using graphics processing unit (GPU) hardware. With the GPU-accelerated waveforms in hand, a variety of studies are performed including an analysis of EMRI mode content, template mismatch, and fully Bayesian Markov Chain Monte Carlo-based EMRI parameter estimation. We find relativistic EMRI waveform templates can be generated with fewer harmonic modes ($\sim 10–100$) without biasing signal extraction. However, we show for the first time that extraction of a relativistic injection with semirelativistic amplitudes can lead to strong bias and anomalous structure in the posterior distribution for certain regions of parameter space.

The next generation of gravitational wave observatories will reach low frequency limits on the orders of a few Hz, thus enabling the detection of gravitational wave signals of very long duration. The run time of standard parameter estimation techniques with these long waveforms can be months or even years, making it impractical with existing Bayesian inference pipelines. Reduced order modeling and the reduced order quadrature integration rule have recently been exploited as promising techniques that can greatly reduce parameter estimation computational costs. We describe a Python-based reduced order quadrature building code, pyroq, which builds the reduced order quadrature data needed to accelerate parameter estimation of gravitational waves. We present the first bases for the imrphenomxphm waveform model of binary-black-hole coalescences, including subdominant harmonic modes and precessing spins effects.