The direct detection of sub-GeV dark matter interacting with nucleons is hampered by the low recoil energies induced by scatterings in the detectors. This experimental difficulty is avoided in the scenario of boosted dark matter where a component of dark matter particles is endowed with large kinetic energies. In this paper, we point out that the current evaporation of primordial black holes with a mass from ${10}^{14}$ to ${10}^{16}\mathrm{g}$ is a source of boosted light dark matter with energies of tens to hundreds of MeV. Focusing on the XENON1T experiment, we show that these relativistic dark matter particles could give rise to a signal orders of magnitude larger than the present upper bounds. Therefore, we are able to significantly constrain the combined parameter space of primordial black holes and sub-GeV dark matter. In the presence of primordial black holes with masses of ${10}^{15}\mathrm{g}$ and abundances compatible with present bounds, the limits on a dark matter-nucleon cross section are improved by four orders of magnitude.

The Hubble tension, if not caused by any systematics, could be relieved or even resolved from modifying either the early-time or late-time Universe. The early-time modifications are usually in tension with either galaxy clustering or galaxy lensing constraints. The late-time modifications are also in conflict with the constraint from the inverse distance ladder, which, however, is weakened by the dependence on a sound-horizon prior and some particular approximation for the late-time expansion history. To achieve a more general no-go argument for the late-time scenarios, we propose to use a global parametrization based on the cosmic age to consistently use the cosmic chronometers data beyond the Taylor expansion domain and without the input of a sound-horizon prior. Both the early-time and late-time scenarios are therefore largely ruled out, indicating the possible ways out of the Hubble tension from either exotic modifications of our concordance Universe or some unaccounted for systematics.

We study the Wishart-Sachdev-Ye-Kitaev (WSYK) model consisting of two $\widehat{q}$-body Sachdev-Ye-Kitaev (SYK) models with general complex couplings, one the Hermitian conjugate of the other, living in off-diagonal blocks of a larger WSYK Hamiltonian. The spectrum is positive with a hard edge at zero energy. We employ diagrammatic and combinatorial techniques to compute analytically the low-order moments of the Hamiltonian. In the limit of large number $N$ of Majoranas, we have found striking similarities with the moments of the weight function of the Al-Salam-Chihara $Q$-Laguerre polynomials. For $\widehat{q}=3$, 4, the $Q$-Laguerre prediction, with $Q=Q(\widehat{q},N)$ also computed analytically, agrees well with exact diagonalization results for $30<N\le 34$ while we observe some deviations for $\widehat{q}=2$. The most salient feature of the spectral density is that, for odd $\widehat{q}$, low-energy excitations grow as a stretched exponential, with a functional form different from that of the supersymmetric SYK model. For $\widehat{q}=4$, a detailed analysis of level statistics reveals quantum chaotic dynamics even for time scales substantially shorter than the Heisenberg time. More specifically, the spacing ratios in the bulk of the spectrum and the microscopic spectral density and the number variance close to the hard edge are very well approximated by that of an ensemble of random matrices that, depending on $N$, belong to the chiral or superconducting universality classes. In particular, we report the first realization of level statistics belonging to the chiral Gaussian Unitary Ensemble universality class, which completes the tenfold-way classification in the SYK model.

In relativistic quantum field theory (QFT) ideal measurements of certain observables are physically impossible without violating causality. This prompts two questions: (i) can a given observable be ideally measured in QFT, and (ii) if not, in what sense can it be measured? Here we formulate a necessary and sufficient condition that any measurement, and more generally any state update (quantum operation), must satisfy to respect causality in real scalar QFT. We argue that for unitary ‘kicks’ and operations involving 1-parameter families of Kraus operators, e.g., Gaussian measurements, the only causal observables are smeared fields and the identity—the basic observables in real scalar QFT. We provide examples with more complicated operators such as products of smeared fields, and show that the associated state updates are acausal, and hence impossible. Despite this, one can still recover expectation values of such operators, and we show how to do this using only causal measurements of smeared fields.

We explore alternate theories of gravity where the gravitational term in the Lagrangian $\frac{R}{8\pi G}$ is replaced by a function $f_1(R)$ and the matter Lagrangian is multiplied by a function $f_2(R)$. We argue that nuclear physics can provide strong experimental constraints on such theories. In particular using energy conditions on the pressure in the ${}^4\mathrm{He}$ nucleus, for $f_1(R)=\frac{R}{8\pi G}$ and $f_2(R)=1+\lambda R$, we find a limit of $|\lambda |<5\times {10}^{-12}{\mathrm{m}}^2$, more than thirty orders of magnitude stronger than the previous limit.

We have recently proposed a model for a regular black hole, or an ultracompact object, that is premised on having maximally negative radial pressure throughout the entirety of the object’s interior. This model can be viewed as that of a highly entropic configuration of fundamental, closed strings near the Hagedorn temperature, but from the perspective of an observer who is ignorant about the role of quantum physics in counteracting against gravitational collapse. The advantage of this classical perspective is that one can use Einstein’s equations to define a classical geometry and investigate its stability. Here, we complete the model by studying an important aspect of this framework that has so far been overlooked: The geometry and composition of the outermost layer of the ultracompact object, which interpolates between the bulk geometry of the object and the standard Schwarzschild vacuum solution in its exterior region. By imposing a well-defined set of matching conditions, we find a metric that describes this transitional layer and show that it satisfies all the basic requirements; including the stability of the object when subjected to small perturbations about the background solution. In fact, we are able to show that, at linearized order, all geometrical and matter fluctuations are perfectly frozen in the transitional layer, just as they are known to be in the bulk of the object’s interior.

We describe a novel twistorial construction of the asymptotic Bondi-Metzner-Sachs (BMS) symmetries at null infinity for asymptotically flat spacetimes. We define BMS twistors as spinor solutions to some set of components of the usual spacetime twistor equation restricted to null infinity. The space of BMS twistors is infinite dimensional. We show that given two BMS twistors, their symmetric tensor product can be used to generate (complex) vector fields which are the infinitesimal BMS symmetries of null infinity. In this sense, BMS twistors are “square roots” of BMS symmetries. We also show that these BMS twistor equations can be written a pair of covariant spinor-valued equations which are completely determined by the intrinsic universal structure of null infinity.

We describe a new kind of resonance occurring in relativistic three-body hierarchical systems—the precession resonance—occurring when the relativistic precession time scale of a binary equals the period of a distant perturber. We find that, contrary to what most previous studies assumed, it can lead to an exponential increase of the eccentricity of the binary even when relativistic precession dominates the quadrupolar perturbation. The resonance may happen in the observation band of LISA or change the eccentricity distribution of triples. We discuss the physics of the resonance, showing that it mainly depends on three parameters.

We examine the shape of the primordial black hole mass distribution arising from a peak in the primordial power spectrum. In light of improvements to the modeling, we revisit the claim that the effects of critical collapse produce a distribution that is not described by the commonly assumed lognormal, showing that this conclusion remains valid, particularly for narrow peaks where the shape of the mass distribution is insensitive to the peak properties and critical collapse determines a minimum width. We propose some alternative models that may better describe the shape, both for the narrow peak case and for much broader peaks where the effect of the peak shape is significant. We highlight the skew-lognormal and a generalized model motivated by the physics of critical collapse as the best of these possible alternatives. These models can be used as an accurate and fast approximation to the numerically calculated mass distribution, allowing for efficient implementation in an MCMC analysis. We advocate the use of one of these two models instead of the lognormal with sufficiently accurate data, such as future LIGO–Virgo observations, or when considering strongly mass dependent constraints on the PBH abundance.

We show that a nonstandard cosmological history with a period of early matter domination driven by a sub-TeV visible-sector particle can arise rather naturally. This scenario involves a long-lived standard model (SM) singlet that acquires a thermal abundance at high temperatures from decays and inverse decays of a parent particle with SM charge(s), and subsequently dominates the energy density of the Universe as a frozen species. Entropy generation at the end of early matter domination dilutes the abundance of dangerous relics (such as gravitinos) by a factor as large as ${10}^4$. The scenario can accommodate the correct dark matter relic abundance for cases with $⟨{\sigma }_{\mathrm{ann}}v{⟩}_{\mathrm{f}}\lessgtr 3\times {10}^{-26}{\mathrm{cm}}^3{\mathrm{s}}^{-1}$. More importantly, the allowed parameter space can be directly probed by proposed searches for neutral long-lived particles at the energy frontier, allowing us to use particle physics experiments to reconstruct the cosmological history just prior to big bang nucleosynthesis.

As massive gravity and its extensions offer physically well-defined gravitational theories with a nonzero graviton mass, we present a new extension of the de Rham–Gabadadze-Tolley massive gravity, which is a tachyonic massive gravity theory. We first introduce the new extension of the de Rham–Gabadadze-Tolley massive gravity, constructed by adding a tachyonic term. We then find the cosmological background equations, and present the analysis of self-accelerating solutions. We examine the tensor perturbations to calculate the dispersion relation of gravitational waves (GWs). In a special case, we consider a constant tachyon potential for the tachyon field $\sigma$, $V(\sigma )=2\omega /M_{\mathrm{Pl}}^2$, and calculate the equations of motion and the self-accelerating solutions. Finally, we investigate the background perturbations, which include tensor, vector, and scalar perturbations in this case. We calculate the dispersion relation of GWs in the Friedmann-Lemaître-Robertson-Walker cosmology in a tachyonic massive gravity theory. These analyses provide potential inputs to future applications in cosmology and GW propagations.

Measuring the polarization fractions of the $W^{+}{W}^{-}$ scattering reveals the interactions of the Higgs boson as well as new neutral states that are related to the standard model electroweak symmetry breaking. The dileptonic channel has a relatively lower background rate, but the kinematics of its final states cannot be fully reconstructed due to the presence of two neutrinos. We propose neural networks to establish maps between the distributions of measurable quantities and the distributions of the lepton angles in $W$ boson rest frames. New physics contributions and collision energy can largely affect the kinematic properties of the $W^{+}{W}^{-}$ scattering beside the lepton angles. To make the network applicable to processes with varying kinematics, the loss function is modified in two different ways. We show that the networks are promising in reproducing the lepton angle distributions, and the precision of the fitted polarization fractions obtained from network predictions is comparable to that obtained with the truth lepton angle. Although the best-fit values of the polarization fractions do not change much after including the background uncertainty, the precision is substantially reduced.

We present results of the first lattice QCD calculations of the weak matrix elements for the decays $B_c^{+}\to D^0{\ell }^{+}{\nu }_{\ell }$, $B_c^{+}\to D_s^{+}{\ell }^{+}{\ell }^{-}$ and $B_c^{+}\to D_s^{+}\nu \overline{\nu }$. Form factors across the entire physical $q^2$ range are then extracted and extrapolated to the continuum limit with physical quark masses. Results are derived from correlation functions computed on MILC Collaboration gauge configurations with three different lattice spacings and including $2+1+1$ flavors of sea quarks in the highly improved staggered quark (HISQ) formalism. HISQ is also used for all of the valence quarks. The uncertainty on the decay widths from our form factors for $B_c^{+}\to D^0{\ell }^{+}{\nu }_{\ell }$ is similar in size to that from the present value for $V_{ub}$. We obtain the ratio $\mathrm{\Gamma }(B_c^{+}\to D^0{\mu }^{+}{\nu }_{\mu })/{|{\eta }_{\mathrm{EW}}{V}_{ub}|}^2=4.43(63)\times {10}^{12}{\mathrm{s}}^{-1}$. Combining our form factors with those found previously by HPQCD for $B_c^{+}\to J/\psi {\mu }^{+}{\nu }_{\mu }$, we find ${|V_{cb}/V_{ub}|}^2\mathrm{\Gamma }(B_c^{+}\to D^0{\mu }^{+}{\nu }_{\mu })/\mathrm{\Gamma }(B_c^{+}\to J/\psi {\mu }^{+}{\nu }_{\mu })=0.257(36{)}_{B_c\to D}(18{)}_{B_c\to J/\psi }$. We calculate the differential decay widths of $B_c^{+}\to D_s^{+}{\ell }^{+}{\ell }^{-}$ across the full $q^2$ range and give integrated results in $q^2$ bins that avoid possible effects from charmonium and $u\overline{u}$ resonances. For example, we find that the ratio of differential branching fractions integrated over the range $q^2=1{\mathrm{GeV}}^2–6{\mathrm{GeV}}^2$ for $B_c^{+}\to D_s^{+}{\mu }^{+}{\mu }^{-}$ and $B_c^{+}\to J/\psi {\mu }^{+}{\nu }_{\mu }$ is $6.31(90{)}_{B_c\to D_s}(65{)}_{B_c\to J/\psi }\times {10}^{-6}$. We also give results for the branching fraction of $B_c^{+}\to D_s^{+}\nu \overline{\nu }$. Prospects for reducing our errors in the future are discussed.

We determine the properties of generalized parton distributions (GPDs) from a lattice QCD calculation of the off-forward Compton amplitude (OFCA). By extending the Feynman-Hellmann relation to second-order matrix elements at off-forward kinematics, this amplitude can be calculated from lattice propagators computed in the presence of a background field. Using an operator product expansion, we show that the deeply virtual part of the OFCA can be parametrized in terms of the low-order Mellin moments of the GPDs. We apply this formalism to a numerical investigation for zero-skewness kinematics at two values of the soft momentum transfer, $t=-1.1,-2.2{\mathrm{GeV}}^2$, and a pion mass of $m_{\pi }\approx 470\mathrm{MeV}$. The form factors of the lowest two moments of the nucleon GPDs are determined, including the first lattice QCD determination of the $n=4$ moments. Hence we demonstrate the viability of this method to calculate the OFCA from first principles, and thereby provide novel constraint on the $x$- and $t$-dependence of GPDs.

In this article, we study the ground-state mass of full-heavy tetraquarks $cc\overline{c}\overline{c}$ and $bb\overline{b}\overline{b}$ with solving the nonrelativistic four-body systems. The flux-tube configurations, the tetraquark four-body potential butterfly, and the dimeson potential flip-flop of SU(3) lattice quantum chromodynamics have been applied to describe the tetraquark interaction. Our numerical analysis indicates that the disconnected and connected static potentials can predict the mass of tetraquark very close to experimental data.

In this work, from the experimental data we evaluate the first C-moments of the multiplicity distributions recently measured in proton-proton collisions at the LHC and compare them with the predictions of two models: the Kharzeev-Levin model and the Bialas-Praszalowicz model. We divide the data into three sets according to their phase space coverage: I: $p_T>100\mathrm{MeV}$ and $|\eta |<0.5$; II: $p_T>100\mathrm{MeV}$ and $|\eta |<2.4$ and III: $p_T>500\mathrm{MeV}$ and $|\eta |<2.4$. The mean multiplicity grows with the energy according to a power law and the power is different for each set. The $C_n$ moments grow continuously with the energy, slowly in Set I and faster in the other sets. Except for KL in Set II, both models reproduce the main features of the data. The negative binomial parameter $k$ decreases continuously with the energy and there is no sign of change in this behavior.

We introduce a jet tagger based on a neural network analyzing the Minkowski functionals (MFs) of pixelated jet images. The MFs are geometric measures of binary images, and they can be regarded as a generalization of the particle multiplicity, which is an important quantity in jet tagging. Their changes by dilation encode the jet constituents’ geometric structures that appear at various angular scales. We explicitly show that this analysis using the MFs and dilation can be considered a constrained convolutional neural network (CNN). Conversely, CNN could model the MFs in the limit of a large network. We show an example that the CNN decision boundary correlates strongly with the value of MFs in semivisible jet tagging of a hidden valley scenario. The MFs are independent of the infrared and collinear (IRC)-safe observables commonly used in jet physics. We combine this morphological analysis with an IRC-safe relation network which models two-point energy correlations. While the resulting network uses constrained input parameters, it shows comparable dark jet and top jet tagging performances to the CNN. The architecture has significant computational advantages when the available data is limited. We show that its tagging performance is much better than that of the CNN with a small number of training samples. We also qualitatively discuss their parton shower model dependency. The results suggest that the MFs can be an efficient parametrization of the IRC-unsafe feature space of jets.

The $\mathrm{AdS}/\mathrm{CFT}$ correspondence provides a unique way to study the vortex matter phases in superconductors. We solve the dynamical evolution of a superconductor in $2+1$ dimensions at a finite temperature subjected to a magnetic field quench in terms of a gravitational “hairy black hole” dual living in an asymptotic ${\mathrm{AdS}}_4$ space. We exploit this to determine the nature of the equilibrium states realized at long times after the quench of this two dimensional type II superconductor in a perpendicular external uniform magnetic field $B_0$. This holographic superconductor exhibits the generic lower ($B_{c1}(T)$) and upper ($B_{c2}(T)$) critical fields. For $B_0<B_{c1}(T)$ the magnetic field is completely expelled revealing the Meissner phase, while the superconductivity is destroyed when $B_0>B_{c2}(T)$. Abrikosov lattices appear in the range $B_{c1}(T)<B_0<B_{c2}(T)$ that realize various configurations in the form of hexagonal, square and slightly irregular square lattices pending the magnetic field strength and the influence of finite size boundaries. We show this to be consistent with the expectations of Ginzburg-Landau theory where the upper and lower critical fields are associated with the inverse squares of the coherence length and magnetic penetration depth, respectively.

Using a data sample of $\psi (3770)$ events collected with the BESIII detector at BEPCII corresponding to an integrated luminosity of $2.9{\mathrm{fb}}^{-1}$, we report a measurement of $\mathrm{\Lambda }$ spin polarization in $e^{+}{e}^{-}\to \mathrm{\Lambda }\overline{\mathrm{\Lambda }}$ at $\sqrt{s}=3.773\mathrm{GeV}$. The significance of polarization is found to be $2\sigma$ including the systematic uncertainty, which implies a zero phase between the transition amplitudes of the $\mathrm{\Lambda }\overline{\mathrm{\Lambda }}$ helicity states. This phase can be interpreted in terms of psionic form factors, and is determined to be $\mathrm{\Delta }{\mathrm{\Phi }}^{\mathrm{\Psi }}={\mathrm{\Phi }}_E^{\mathrm{\Psi }}-{\mathrm{\Phi }}_M^{\mathrm{\Psi }}=(71_{-46}^{+66}\pm 5)°$. Similarly, the ratio between the form factors is found to be $R^{\psi }=|G_E^{\mathrm{\Psi }}/G_M^{\mathrm{\Psi }}|=0.48_{-0.35}^{+0.21}\pm 0.03$. The first uncertainties are statistical and the second systematic.

We initiate a study into the eikonal exponentiation of the amplitude in impact-parameter space when spinning particles are involved in the scattering. Considering the gravitational scattering of two spin-$1/2$ particles, we demonstrate that the leading eikonal exhibits exponentiation up to $\mathcal{O}(G^2)$ in the limit where the spacetime dimension $D\to 4$. We find this to hold for general spin orientations. The exponentiation of the leading eikonal including spin is understood through the unitarity properties at leading order in $\hslash$ of momentum-space amplitudes, allowing the extension of our arguments to arbitrary-spin scattering.