The dark matter subhalo mass function is a promising way of distinguishing between dark matter models. While cold dark matter predicts halos down to Earth-sized masses, other dark matter models typically predict a cutoff in the subhalo mass function. Thus a definitive detection or limits on the existence of subhalos at small masses can give us insight into the nature of dark matter. If these subhalos exist in the Milky Way, they would produce weak lensing signatures, such as modified apparent positions, on background stars. These signatures would generate correlations in the apparent velocities and accelerations of these stars, which could be observable given sufficient astrometric resolution and cadence. The Nancy Grace Roman Space Telescope’s exoplanet microlensing survey will be perfectly suited to measuring the acceleration signatures of these halos. Here we forward model these acceleration signatures and explore the Roman Space Telescope’s future constraints on lens profiles and populations. We find that the Roman Space Telescope could place competitive bounds on point-source, Gaussian, and Navarro-Frenk-White (NFW) profile lenses that are complementary to other proposed methods. In particular, it could place 95% upper limits on the NFW concentration $c_{200}<{10}^{2.5}$. We discuss possible systematic effects that could hinder these efforts but argue they should not prevent the Roman Space Telescope from placing strong limits. We also discuss further analysis methods for improving these constraints.

The physics of reheating can provide additional predictions for inflationary models and thus has spurred an increasing deal of interest. In this paper, by considering a special function for the decay of the inflaton into radiation, which renders the effective equation of state (EoS) parameter to be time varying during reheating, we investigate the constraints on reheating from the cosmic microwave background observations and the effect of reheating on the predictions for inflationary models. Our work is different from previous ones where a constant EoS parameter is assumed. Taking the power-law inflationary models as concrete examples, we find that the time-varying EoS parameter during reheating entails a non-negligible effect on the reheating predictions.

Recently, the LIGO-Virgo Collaboration (LVC) has concluded there is no evidence for lensed gravitational waves (GWs) in the first half of the O3 run [LIGO Scientific Collaboration and Virgo Collaboration, Search for lensing signatures in the gravitational-wave observations from the first half of LIGO-Virgo’s third observing run], claiming “We find the observation of lensed events to be unlikely, with the fractional rate at $\mu >2$ being $3.3\times {10}^{-4}$.” While we agree that the chance of an individual GW event being lensed at $\mu >2$ is smaller than $<{10}^{-3}$, the number of observed events depends on the product of this small probability times the rate of mergers at high redshift. Observational constraints from the stochastic GW background indicate that the rate of conventional mass binary black hole (BBH) mergers ($8<M/M_{\odot }<15$) in the redshift range $1<z<2$ could be as high as O(${10}^7$) events per year, more than sufficient to compensate for the intrinsically low probability of lensing. To reach the LVC trigger threshold, these events require high magnification but would still produce up to 10–30 LVC observable events per year. Thus, all the LVC observed ordinary stellar mass BBH mergers from this epoch must be strongly lensed with as many as ${10}^6{\mathrm{yr}}^{-1}$ events lying below the current detection threshold. By adopting a low BBH coalescence rate at high redshift, LVC implicitly assume that lensed events are insignificant and, thus, incorrectly underestimate the distances of most BBH events and correspondingly overestimate masses by factors of 2–5. Furthermore, the LVC adopted priors on time delay for ideal circularly symmetric lenses are in tension with the known distribution of observed time delays of lensed quasars that require elliptical potentials with a broad spread of time delays. Pairs of events like GW190421_213856GW190910_112807 and GW190424_180648GW190910_112807, which are directly assigned a probability of zero by LVC, should instead be considered as candidate lensed BBH pairs, since their separation in time is typical of lensed quasars. Replacing the LVC model prior for the time delay distribution with the empirical quasar-based distribution reverses the LVC conclusions and says that a significant fraction of BBH pairs identified by LVC are viable multiply lensed events, including quadruple systems.

Recently, Meneghetti et al. reported an excess of small-scale gravitational lenses in galaxy clusters. We study its implications for self-interacting dark matter (SIDM) compared with standard cold dark matter (CDM). We design controlled $N$-body simulations that incorporate observational constraints. The presence of early-type galaxies in cluster substructures can deepen gravitational potential and reduce tidal mass loss. Both scenarios require a relatively high baryon concentration in the substructure to accommodate the lensing measurements, and their tangential caustics are similar. The SIDM substructure can experience gravothermal collapse and produce a steeper density profile than its CDM counterpart, leading to a larger radial galaxy-galaxy strong-lensing cross section, although this effect is hard to observe. Our results indicate that SIDM can provide a unified explanation to small-scale lenses in galaxy clusters and stellar motion in dwarf galaxies.

The effect of the pulse envelope on electron-positron pair creation in a circularly polarized laser pulse is investigated. Interference on the length scale of the pulse envelope, and smoothness of the pulse edges are found to influence the pair spectrum. A toy model of a flat-top pulse is used to identify pulse envelope effects inaccessible to local approaches. Broadening of channel openings and a widening of the energy and transverse momentum distribution of the pair are found to receive contributions that are below the local harmonic threshold. By comparing pair yields in a flat-top, sine-squared and Gaussian pulse, a link between pulse shape and photon-polarized Breit-Wheeler pair creation is found. In the transverse momentum distribution, a signal of pulse envelope interference is found in an azimuthal asymmetry, which appears in intense fields and persists in long pulses.

Recent works have revealed that matching conditions play a major role in general consistency properties of relativistic fluid dynamics, such as causality, stability, and well posedness of the equations of motion. In this paper we derive transient fluid dynamics from kinetic theory, using the method of moments as proposed by Israel and Stewart, without imposing a specific matching condition. We then investigate how the equations of motion and their corresponding transport coefficients are affected by the choice of matching condition.

In our recent companion paper [Fedderke et al. Phys. Rev. D 104, 075023 (2021)], we pointed out a novel signature of ultralight kinetically mixed dark-photon dark matter. This signature is a quasimonochromatic, time-oscillating terrestrial magnetic field that takes a particular pattern over the surface of Earth. In this work, we present a search for this signal in existing, unshielded magnetometer data recorded by geographically dispersed, geomagnetic stations. The dataset comes from the SuperMAG Collaboration and consists of measurements taken with one-minute cadence since 1970, with $\mathcal{O}(500)$ stations contributing in all. We aggregate the magnetic field measurements from all stations by projecting them onto a small set of global vector spherical harmonics (VSH) that capture the expected vectorial pattern of the signal at each station. Within each dark-photon coherence time, we use a data-driven technique to estimate the broadband background noise in the data, and search for excess narrow-band power in this set of VSH components; we stack the searches in distinct coherence times incoherently. Following a Bayesian analysis approach that allows us to account for the stochastic nature of the dark-photon dark-matter field, we set exclusion bounds on the kinetic-mixing parameter in the dark-photon dark-matter mass range $2\times {10}^{-18}\mathrm{eV}\lesssim m_{A^{\prime }}\lesssim 7\times {10}^{-17}\mathrm{eV}$ (corresponding to frequencies $6\times {10}^{-4}\mathrm{Hz}\lesssim f_{A^{\prime }}\lesssim 2\times {10}^{-2}\mathrm{Hz}$). These limits are complementary to various existing astrophysical constraints. Although our main analysis also identifies a number of candidate signals in the SuperMAG dataset, these appear to either fail or be in tension with various additional robustness checks we apply to those candidates. We report no robust and significant evidence for a dark-photon dark-matter signal in the SuperMAG dataset.

The dark photon is a massive hypothetical particle that interacts with the Standard Model by kinetically mixing with the visible photon. For small values of the mixing parameter, dark photons can evade cosmological bounds to be a viable dark matter candidate. Due to the similarities with the electromagnetic signals generated by axions, several bounds on dark photon signals are simply reinterpretations of historical bounds set by axion haloscopes. However, the dark photon has a property that the axion does not: an intrinsic polarization. Due to the rotation of the Earth, accurately accounting for this polarization is nontrivial, highly experiment dependent, and depends upon assumptions about the dark photon’s production mechanism. We show that if one does account for the dark photon polarization, and the rotation of the Earth, an experiment’s discovery reach can be enhanced by over an order of magnitude. We detail the strategies that would need to be taken to properly optimize a dark photon search. These include judiciously choosing the location and orientation of the experiment, as well as strategically timing any repeated measurements. Experiments located at $\pm 35°$ or $\pm 55°$ latitude, making three observations at different times of the sidereal day, can achieve a sensitivity that is fully optimized and insensitive to the dark photon’s polarization state, and hence its production mechanism. We also point out that several well-known searches for axions employ techniques for testing signals that preclude their ability to set exclusion limits on dark photons, and hence should not be reinterpreted as such.

We investigate low-scale resonant leptogenesis in an $SU(5)\times {\mathcal{T}}_{13}$ model where a single high-energy phase in the complex tribimaximal seesaw mixing produces the yet to be observed low-energy Dirac and Majorana $CP$ phases. A fourth right-handed neutrino, required to generate viable light neutrino masses within this scenario, also turns out to be necessary for successful resonant leptogenesis where $CP$ asymmetry is produced by the same high-energy phase. We derive a lower bound on the right-handed neutrino mass spectrum in the GeV range, where part of the parameter space, although in tension with big bang nucleosynthesis constraints, can be probed in planned high-intensity experiments like DUNE. We also find the existence of a curious upper bound (TeV-scale) on the right-handed neutrino mass spectrum in majority of the parameter space due to significant washout of the resonant asymmetry by lighter right-handed neutrinos. While in most of the parameter space of our model classical Boltzmann equations are sufficient, when right-handed neutrino masses are below the electroweak sphalerons freeze-out temperature we resort to the more general density matrix formalism to take into account decays and oscillations of the right-handed neutrinos as well as their helicities which are relevant when they are relativistic.

The impact of axionlike particles (ALPs) on the search of permanent electric dipole moments (EDMs) of molecules, atoms, nuclei and nucleons is systematically investigated. Assuming the most general ALP effective field theory containing operators up to dimension-five, we evaluate the leading short-distance effects to the EDMs at two-loop order. The high sensitivity of EDMs to $CP$-violating ALP interactions is emphasized exploiting both the current and projected experimental sensitivities.

We study the inclusion of $\mathcal{O}(1/{\mathrm{\Lambda }}^4)$ effects in the Standard Model effective field theory in fits to the current Drell-Yan data at the LHC. Our analysis includes the full set of dimension-6 and dimension-8 operators contributing to the dilepton process, and is performed to next-to-leading-order in the QCD coupling constant at both $\mathcal{O}(1/{\mathrm{\Lambda }}^2)$ and $\mathcal{O}(1/{\mathrm{\Lambda }}^4)$. We find that the inclusion of dimension-6 squared terms and certain dimension-8 operators has significant effects on fits to the current data. Neglecting them leads to bounds on dimension-6 operators off by large factors. We find that dimension-8 four-fermion operators can already be probed to the several-TeV level by LHC results, and that their inclusion significantly changes the limits found for dimension-6 operators. We discuss which dimension-8 operators should be included in fits to the LHC data. Only a manageable subset of two-derivative dimension-8 four-fermion operators need to be included at this stage given current LHC uncertainties.

The Higgs boson may well be a composite scalar with a finite extension in space. Owing to the momentum dependence of its couplings, the imprints of such a composite pseudo Goldstone Higgs may show up in the tails of various kinematic distributions at the LHC, distinguishing it from an elementary state. From the bottom up, we construct the momentum-dependent form factors to capture the interactions of the composite Higgs with the weak gauge bosons. We demonstrate their impact in the differential distributions of various kinematic parameters for the $pp\to Z^{*}H\to l^{+}{l}^{-}b\overline{b}$ channel. We show that this channel can provide an important handle to probe the Higgs’ substructure at the HL-LHC.

With advances in quantum computing, new opportunities arise to tackle challenging calculations in quantum field theory. We show that trotterized time-evolution operators can be related by analytic continuation to the Euclidean transfer matrix on an anisotropic lattice. In turn, trotterization entails renormalization of the temporal and spatial lattice spacings. Based on the tools of Euclidean lattice field theory, we propose two schemes to determine Minkowski lattice spacings, using Euclidean data and thereby overcoming the demands on quantum resources for scale setting. In addition, we advocate using a fixed-anisotropy approach to the continuum to reduce both circuit depth and number of independent simulations. We demonstrate these methods with qiskit noiseless simulators for a $2+1\mathrm{D}$ discrete non-Abelian $D_4$ gauge theory with two spatial plaquettes.

The finite temperature phase diagram of QCD with two massless quark flavors is not yet understood because of the subtle effects of anomalous $U_A(1)$ symmetry. In this work we address this issue by studying the fate of the anomalous $U_A(1)$ symmetry in $2+1$ flavor QCD just above the chiral crossover transition temperature $T_c$, lowering the light quark mass toward the chiral limit along the line of constant physical strange quark mass. We use the gauge configurations generated using the highly improved staggered quark discretization on lattice volumes ${32}^3\times 8$ and ${56}^3\times 8$ to study the renormalized eigenvalue spectrum of QCD with a valence overlap Dirac operator. We implement new numerical techniques that allow us to measure about 100–200 eigenvalues of the gauge ensembles with light quark masses $\gtrsim 0.6\mathrm{MeV}$. From a detailed analysis of the dependence of the renormalized eigenvalue spectrum and $U_A(1)$ breaking observables on the light quark mass, our study suggests $U_A(1)$ is broken at $T\gtrsim T_c$ even when the chiral limit is approached.

We calculate thermodynamic potentials and their derivatives for the three-dimensional $O(2)$ model using tensor-network methods to investigate the well-known second-order phase transition. We also consider the model at nonzero chemical potential to study the Silver Blaze phenomenon, which is related to the particle number density at zero temperature. Furthermore, the temperature dependence of the number density is explored using asymmetric lattices. Our results for both zero and nonzero magnetic field, temperature, and chemical potential are consistent with those obtained using other methods.

In this study, we present a determination of the unpolarized gluon Ioffe-time distribution in the nucleon from a first principles lattice quantum chromodynamics calculation. We carry out the lattice calculation on a ${32}^3\times 64$ ensemble with a pion mass of 358 MeV and lattice spacing of 0.094 fm. We construct the nucleon interpolating fields using the distillation technique, flow the gauge fields using the gradient flow, and solve the summed generalized eigenvalue problem to determine the gluonic matrix elements. Combining these techniques allows us to provide a statistically well-controlled Ioffe-time distribution and unpolarized gluon parton distribution function. We obtain the flow time independent reduced Ioffe-time pseudodistribution and calculate the light-cone Ioffe-time distribution and unpolarized gluon distribution function in the $\overline{\mathrm{MS}}$ scheme at $\mu =2\mathrm{GeV}$, neglecting the mixing of the gluon operator with the quark singlet sector. Finally, we compare our results to phenomenological determinations.

We investigate the Kondo effect with Wilson fermions. This is based on a mean-field approach for the chiral Gross-Neveu model including four-point interactions between a light Wilson fermion and a heavy fermion. For massless Wilson fermions, we demonstrate the appearance of the Kondo effect. We point out that there is a coexistence phase with both the light-fermion scalar condensate and Kondo condensate, and the critical chemical potentials of the scalar condensate are shifted by the Kondo effect. For negative-mass Wilson fermions, we find that the Kondo effect is favored near the parameter region realizing the Aoki phase. Our findings will be useful for understanding the roles of heavy impurities in Dirac semimetals, topological insulators, and lattice simulations.

We have studied the dominant radiative transitions of the charmonium $S$- and $P$-wave states within the covariant confined quark model. The gauge invariant leading-order transition amplitudes have been expressed by using either the conventional Lorentz structures, or the helicity amplitudes, where it was effective. The renormalization couplings of the charmonium states have been strictly fixed by the compositeness conditions that excludes the constituent degrees of freedom from the space of physical states. We use the basic model parameters for the constituent c-quark mass $m_c=1.80\mathrm{GeV}$ and the global infrared cutoff $\lambda =0.181\mathrm{GeV}$. We additionally introduce only one adjustable parameter $\varrho >0$ common for the charmonium states ${\eta }_c({{}^{1}S}_0)$, $J/\psi ({{}^{3}S}_1)$, ${\chi }_{c0}({{}^{3}P}_0)$, ${\chi }_{c1}({{}^{3}P}_1)$, $h_c({{}^{1}P}_1)$, and ${\chi }_{c2}({{}^{3}P}_2)$ to describe the quark distribution inside the hadron. This parameter describes the ratio between the charmonium “size” and its physical mass. The optimal value $\varrho =0.485$ has been fixed by fitting the latest data for the partial widths of the one-photon radiative decays of the triplet ${\chi }_{cJ}({{}^{3}P}_J),J=\{0,1,2\}$. Then, we calculate corresponding fractional widths for states $J/\psi ({{}^{3}S}_1)$ and $h_c({{}^{1}P}_1)$. Estimated results are in good agreement with the latest data. By using the fraction data from PDG2020 and our estimated partial decay width for $h_c({{}^{1}P}_1)$ we recalculate the “theoretical full width” ${\mathrm{\Gamma }}_{h_c}^{\text{theor}}\simeq (0.57\pm 0.12)\mathrm{MeV}$ in comparison with latest data ${\mathrm{\Gamma }}_{h_c}^{\exp }\simeq (0.7\pm 0.4)\mathrm{MeV}$. We also repeated our calculations by gradually decreasing the global cutoff parameter and revealed that the results do not change for any $\lambda <0.181\mathrm{GeV}$ up to the “deconfinement” limit.