With the isovector coupling constants adjusted to reproduce the physical pion mass and lattice QCD results in baryon-free quark matter, we have carried out rigourous calculations for the pion condensate in the three-flavor Nambu-Jona-Lasinio model, and studied the three-dimensional QCD phase diagram. With the increasing isospin chemical potential ${\mu }_I$, we have observed two nonzero solutions of the pion condensate at finite baryon chemical potentials ${\mu }_B$, representing, respectively, the pion superfluid phase and the Sarma phase, and their appearance and disappearance correspond to a second-order (first-order) phase transition at higher (lower) temperatures $T$ and lower (higher) ${\mu }_B$. Calculations by assuming equal constituent mass of $u$ and $d$ quarks would lead to large errors of the QCD phase diagram within ${\mu }_B\in (500,900)\mathrm{MeV}$, and affect the position of the critical end point.

We study gravitational particle production of the massive spin-$3/2$ Rarita-Schwinger field, and its close relative, the gravitino, in Friedmann-Robertson-Walker cosmological spacetimes. For masses lighter than the value of the Hubble expansion rate after inflation, $m_{3/2}\lesssim H$, we find catastrophic gravitational particle production, wherein the number of gravitationally produced particles is divergent, caused by a transient vanishing of the helicity-$1/2$ gravitino sound speed. In contrast with the conventional gravitino problem, the spectrum of produced particles is dominated by those with momentum at the UV cutoff. This suggests a breakdown of effective field theory, which might be cured by new degrees of freedom that emerge in the UV. We study the UV completion of the Rarita-Schwinger field, namely $\mathcal{N}=1$, $d=4$, supergravity. We reproduce known results for models with a single superfield and models with an arbitrary number of chiral superfields, find a simple geometric expression for the sound speed in the latter case, and extend this to include nilpotent constrained superfields and orthogonal constrained superfields. We find supergravity models where the catastrophe is cured and models where it persists. Insofar as quantizing the gravitino is tantamount to quantizing gravity, as is the case in any UV completion of supergravity, the models exhibiting catastrophic production are prime examples of four-dimensional effective field theories that become inconsistent when gravity is quantized, suggesting a possible link to the swampland program. We propose the gravitino swampland conjecture, which is consistent with and indeed follows from the Kachru-Kallosh-Linde-Trivedi and large volume scenarios for moduli stabilization in string theory.

We present a new paradigm, asymptotic grand unification, where the gauge couplings run to a unique fixed point in the ultraviolet, without supersymmetry and without quantitative unification at any given scale. We introduce a minimal model based on an SU(5) gauge theory in a compact $S^1/({\mathbb{Z}}_2\times {\mathbb{Z}}_2^{\prime })$ orbifold. By construction, fermions are embedded in different SU(5) bulk fields. As a consequence, the baryon number is conserved, thus preventing proton decay, and the lightest Kaluza-Klein tier consists of new states that cannot decay into standard model ones. We show that the Yukawa couplings can be either in the bulk or localized and run to an asymptotically free fixed point in the UV. The lightest massive state can play the role of dark matter, produced via baryogenesis, for a Kaluza-Klein mass of about 2.4 TeV.

In this paper we study, by means of numerical simulations, the behavior of the scalar glueball mass and the ground state of the torelon for trace deformed Yang-Mills theory defined on ${\mathbb{R}}^3\times S^1$, in which center symmetry is recovered even at small compactification radii. We find, by investigating both $SU(3)$ and $SU(4)$ pure gauge theories, that the glueball mass computed in the deformed theory, when center symmetry is recovered, is compatible with its value at zero temperature and does not show any significant dependence on the compactification radius; moreover, we establish a connection between the deformation parameter and an effective compactification size, which works well at least for small deformations. In addition, we observe that the ground state of the torelon which winds around the small traced deformed circle with size $l$ acquires a plateau for large values of the strength $h$, with values which are compatible with a $1/l$ behavior but, on the other hand, are still not in complete agreement with the asymptotic semiclassical large-$N$ predictions.

We analytically compute all four-loop QCD corrections to the photon-quark and Higgs-gluon form factors involving a closed massless fermion loop. Our calculation of nonplanar vertex integrals confirms a previous conjecture for the analytical form of the nonfermionic contributions to the collinear anomalous dimensions of quarks and gluons.

In this paper we consider a small-$x$ model for gluon GTMDs that we fit to data on diffractive dijet production in electron-proton collisions obtained by HERA’s H1 Collaboration. Assuming a small number of free parameters, each with a physical motivation, we are able to describe those data fairly well and with this model we obtain predictions for the EIC for both electroproduction and photoproduction which may allow to further test the underlying GTMD description. In the general discussion of the impact parameter dependence we recall some subtle issues related to localization of states, choice of frames, and discuss what these aspects imply for the range of applicability of the model.

We discuss stiffening of matter in quark-hadron continuity. We introduce a model that relates quark wave functions in a baryon and the occupation probability of states for baryons and quarks in dense matter. In a dilute regime, the confined quarks contribute to the energy density through the masses of baryons but do not directly contribute to the pressure; hence, the equations of state are very soft. This dilute regime continues until the low momentum states for quarks get saturated; this may happen even before baryons fully overlap, possibly at density slightly above the nuclear saturation density. After the saturation, the pressure grows rapidly while changes in energy density are modest, producing a peak in the speed of sound. If we use baryonic descriptions for quark distributions near the Fermi surface, we reach a description similar to the quarkyonic matter model of McLerran and Reddy. With a simple adjustment of quark interactions to get the nucleon mass, our model becomes consistent with the constraints from 1.4-solar mass neutron stars, but the high density part is too soft to account for two-solar mass neutron stars. We delineate the relation between the saturation effects and short range interactions of quarks, suggesting interactions that leave low density equations of state unchanged but stiffen the high density part.

Drell Yan production is a sensitive probe of new physics and as such has been calculated to high order in both the electroweak and QCD sectors of the standard model, allowing for precision comparisons between theory and data. Here we extend these calculations to the standard model effective field theory and present the next-to-leading order QCD and electroweak contributions to the neutral Drell-Yan process.

We reexamine direct $CP$ violation in the quasi-two-body $D\to VP$ decays and study $CP$ asymmetries in three-body $D$ decays proceeding through intermediate vector resonances within the framework of the topological amplitude approach for tree amplitudes and the QCD factorization approach for penguin amplitudes. Using the same mechanism of incorporating long-distance penguin-exchange amplitude induced from final-state rescattering that nicely accounts for the $CP$ asymmetry difference between $D^0\to K^{+}{K}^{-}$ and ${\pi }^{+}{\pi }^{-}$ modes, we find that $CP$ asymmetry can also occur at the per mille level in many of the $D\to VP$ channels or otherwise be negligibly small. We point out six golden modes which have sufficiently large branching fractions and direct $CP$ violation of order ${10}^{-3}$. In particular, the direct $CP$ asymmetry difference $\mathrm{\Delta }{a}_{CP}^{VP}$ between $D^0\to K^{+}{K}^{*-}$ and ${\pi }^{+}{\rho }^{-}$ is predicted to be $(-1.61\pm 0.33)\times {10}^{-3}$, very similar to the counterpart in the $PP$ sector. Besides, we find a positive and large $CP$ asymmetry of order ${10}^{-3}$ in $D^0\to K_S{K}^{*0}$, an example of the asymmetry induced at tree level. We take into account the flavor-singlet QCD-penguin contributions to calculate their effects on the modes such as $D\to \pi \varphi$ and $D\to \eta \varphi$. We compare our results with the other approach in detail. For three-body $D$ decays, we perform the Dalitz plot analysis of those decays mediated by several vector resonances with the same mass but different electric charges. Local $CP$ asymmetry varies in magnitude and sign from region to region and can reach the percent level in certain local regions of phase space due to interference.

Liquid argon time projection chambers (LArTPCs) are a class of detectors that produce high resolution images of charged particles within their sensitive volume. In these images, the clustering of distinct particles into superstructures is of central importance to the current and future neutrino physics program. Electromagnetic (EM) activity typically exhibits spatially detached fragments of varying morphology and orientation that are challenging to efficiently assemble using traditional algorithms. Similarly, particles that are spatially removed from each other in the detector may originate from a common interaction. Graph neural networks (GNNs) were developed in recent years to find correlations between objects embedded in an arbitrary space. The graph particle aggregator (GrapPA) first leverages GNNs to predict the adjacency matrix of EM shower fragments and to identify the origin of showers, i.e., primary fragments. On the PILArNet public LArTPC simulation dataset, the algorithm achieves a shower clustering accuracy characterized by a mean purity of 99.4%, a mean efficiency of 99.6% and a primary identification accuracy of 99.8%. It yields a relative shower energy uncertainty of $(4.1+1.4/\sqrt{E(\mathrm{GeV})})\%$ and a shower direction uncertainty of $(2.1/\sqrt{E(\mathrm{GeV})})°$. The optimized algorithm is then applied to the related task of clustering particle instances into interactions and yields a mean purity of 99.8% and a mean efficiency of 99.5% for an interaction density of $\mathcal{O}(1){\mathrm{m}}^{-3}$.

We introduce a new method permitting the analytical determination of entanglement entropy (and related quantities) between configurations of a quantum field, which is either free or in interaction with a classical source, at two distinct spatial locations. We show how such a setup can be described by a bipartite, continuous Gaussian system. This allows us to derive explicit and exact formulas for the entanglement entropy, the mutual information and the quantum discord, solely in terms of the Fourier-space power spectra of the field. This contrasts with previous studies, which mostly rely on numerical considerations. As an illustration, we apply our formalism to massless fields in flat space, where exact expressions are derived that only involve the ratio between the size of the regions over which the field is coarse-grained, and the distance between these regions. In particular, we recover the well-known fact that mutual information decays as the fourth power of this ratio at large distances, as previously observed in numerical works. Our method leads to the first analytical derivation of this result, and to an exact formula that also applies to arbitrary distances. Finally, we determine the quantum discord and find that it identically vanishes (unless coarse-graining is performed over smeared spheres, in which case it obeys the same suppression at large distance as mutual information).

Multipole moments carry a lot of information about the gravitational field. Nonetheless, knowing all the multipole moments of an object does not determine conclusively the nature of the object itself. In particular, the field multipole moments of the Kerr spacetime are not unique. Here we construct several physically motivated Newtonian objects with multipole moments identical to those of Kerr. Moreover, we also provide a description of how to include post-Newtonian corrections to these objects without changing their multipole moments.

Since the initial detection of gravitational waves in 2015, over 50 candidate events have been reported by the LIGO-Virgo-KAGRA collaboration. As the current generation of detectors move toward their design sensitivity, the rate of these detections will increase. The next generation of detectors are likely to have high enough sensitivities that multiple merging binaries will be visible at the same time. In this paper we show that this is likely to happen before the end of the decade, during observations by the LIGO-Voyager detector. We investigate the situation of overlapping binary black hole (BBH) mergers in these detectors. We find that current parameter estimation techniques are capable of distinguishing the louder of two merging BBH events, without significant bias, when their merger times are not less than $\sim 0.1$ seconds apart or when the ratio of the signal-to-noise ratios of the systems is uneven. This region of overlapping parameter space is dependent upon the sky locations of the signals and the relation of those locations to the light travel time between detectors. We also find that, if two signals are highly overlapping, then the recovered set of parameters often show strong evidence of precession. Finally, we show that bias can occur even when the signal causing the bias is below the detection threshold.

We study how inhomogeneities of the cosmological fluid fields backreact on the homogeneous part of energy density and how they modify the Friedmann equations. In general, backreaction requires to go beyond the pressureless ideal fluid approximation, and this can lead to a reduced growth of cosmological large-scale structure. Since observational evidence favors evolution close to the standard growing mode in the linear regime, we focus on two-component fluids in which the nonideal fluid is gravitationally coupled to cold dark matter and in which a standard growing mode persists. This is realized, e.g., for a baryonic fluid coupled to cold dark matter. We calculate the backreaction for this case and for a wide range of other two-fluid models. Here the effect is either suppressed because the nonideal matter properties are numerically too small, or because they lead to a too stringent UV cutoff of the integral over the power spectrum that determines backreaction. We discuss then matter field backreaction from a broader perspective and generalize the formalism such that also far-from-equilibrium scenarios relevant to late cosmological times and nonlinear scales can be addressed in the future.

DarkSide-50 has demonstrated the high potential of dual-phase liquid argon time projection chambers in exploring interactions of WIMPs in the $\mathrm{GeV}/{\mathrm{c}}^2$ mass range. The technique, based on the detection of the ionization signal amplified via electroluminescence in the gas phase, allows us to explore recoil energies down to the sub-keV range. We report here on the DarkSide-50 measurement of the ionization yield of electronic recoils down to $\sim 180{\mathrm{eV}}_{\mathrm{er}}$, exploiting ${}^{37}\mathrm{Ar}$ and ${}^{39}\mathrm{Ar}$ decays, and extrapolated to a few ionization electrons with the Thomas-Imel box model. Moreover, we present a model-dependent determination of the ionization response to nuclear recoils down to $\sim 500{\mathrm{eV}}_{\mathrm{nr}}$, the lowest ever achieved in liquid argon, using in situ neutron calibration sources and external datasets from neutron beam experiments.

We report on an all-sky search for continuous gravitational waves in the frequency band 20–2000 Hz and with a frequency time derivative in the range of $[-1.0,+0.1]\times {10}^{-8}\mathrm{Hz}/\mathrm{s}$. Such a signal could be produced by a nearby, spinning and slightly nonaxisymmetric isolated neutron star in our Galaxy. This search uses the LIGO data from the first six months of Advanced LIGO’s and Advanced Virgo’s third observational run, O3. No periodic gravitational wave signals are observed, and 95% confidence-level (C.L.) frequentist upper limits are placed on their strengths. The lowest upper limits on worst-case (linearly polarized) strain amplitude $h_0$ are $\sim 1.7\times {10}^{-25}$ near 200 Hz. For a circularly polarized source (most favorable orientation), the lowest upper limits are $\sim 6.3\times {10}^{-26}$. These strict frequentist upper limits refer to all sky locations and the entire range of frequency derivative values. For a population-averaged ensemble of sky locations and stellar orientations, the lowest 95% C.L. upper limits on the strain amplitude are $\sim 1.4\times {10}^{-25}$. These upper limits improve upon our previously published all-sky results, with the greatest improvement (factor of $\sim 2$) seen at higher frequencies, in part because quantum squeezing has dramatically improved the detector noise level relative to the second observational run, O2. These limits are the most constraining to date over most of the parameter space searched.

A new exactly solvable case in strong-field quantum electrodynamics with a time-dependent external electric field is presented. The corresponding field is given by one component of the electromagnetic vector potential, which is the analytic function $A_x(t)=\sigma E_0{[1+\exp (t/\sigma )]}^{-1/2}$, where $\sigma$ is a timescale parameter. In contrast to Sauter-like electric field, this field is asymmetric with respect to the time instant, where it reaches its maximum value, that is why we call it the analytic asymmetric electric field. We managed to exactly solve the Dirac equation with such a field, which made it possible to calculate characteristics of the corresponding vacuum instability nonperturbatively. We construct the so-called in- and out-solutions and with their help calculate mean differential and total numbers of created charged particles, probability of the vacuum to remain a vacuum, vacuum mean values of current density and energy-momentum tensor of the particles. We study the vacuum instability in regimes of rapidly and slowly changing analytic asymmetric electric field, and compare the obtained results with corresponding ones obtained earlier for the case of the symmetric Sauter-like electric field. We also compare exact results in the regime of slowly changing field with corresponding results obtained within the slowly varying field approximation proposed by two of the authors in [S. P. Gavrilov and D. M. Gitman, Phys. Rev. D 95, 076013 (2017)], thus demonstrating the effectiveness of such an approximation.

We analytically calculate the perturbation expansion of the two-point correlation function (propagator) of the scalar, dissipative quantum ${\phi }^4$ theory up to third order in the interaction parameter $\lambda$. The calculations are carried out with two different methods. The first is based on a brute force computation of all interactions appearing in the perturbation expansion term by term at the given order of the perturbation, supported by the use of a symbolic mathematical code. The second uses an efficient perturbation scheme which allows one to hierarchically organize terms within a given order in the perturbation expansion based on the number of occurrences of the free evolution operator ${\mathcal{R}}_s^{\mathrm{free}}$; in addition, it allows one to utilize information from already computed lower-order terms in the calculation of higher-order terms. The two methods yield the same result. In the limit of zero dissipation (zero friction coefficient $\gamma$), our result coincides with that obtained from the Lagrangian approach in $D=d+1$ dimensions ($d$ denotes the number of space dimensions, while $D$ includes the time dimension) with the use of $D$-dimensional vectors, re-expressed in terms of only $d$-dimensional space integrals by integrating out the zero component. We have also verified that the value of the critical coupling constant ${\lambda }^{*}$ as a function of space dimensionality $d$, which can be used to evaluate perturbation expansions at the physical length scale ${\ell }_m$, comes out correctly from our third-order calculation.

As fermions are added to a lattice gauge theory, one is driven to stronger bare coupling in order to maintain the same renormalized coupling. Stronger bare couplings are usually associated with larger gauge fluctuations, leading to larger cutoff effects and more expensive simulations. In theories with many light fermions, sometimes the desired physical region cannot be reached before encountering a phase boundary. We show that these undesired effects can be reduced by adding Pauli-Villars fields. We reach significantly larger renormalized couplings while at the same time damping short-distance fluctuations of the gauge field. This may allow for controlled continuum extrapolations from large lattice spacings.

We study numerically the chromoelectric-chromomagnetic asymmetry of the dimension two $A^2$ gluon condensate as well as the infrared behavior of the gluon propagators at $T\simeq T_c$ in the Landau-gauge $SU(3)$ lattice gauge theory. We find that a very significant correlation of the real part of the Polyakov loop with the asymmetry as well as with the longitudinal propagator makes it possible to determine the critical behavior of these quantities. We obtain the screening masses in different Polyakov-loop sectors and discuss the dependence of chromoelectric and chromomagnetic interactions of static color charges and currents on the choice of the Polyakov-loop sector in the deconfinement phase.