Searching for physics beyond the Standard Model is one of the main tasks of experimental physics. Candidates for dark matter include axionlike ultralight bosonic particles. Comagnetometers form ultrahigh sensitivity probes for such particles and any exotic field that interacts with the spin of an atom. Here, we propose a multiatom-species probe that enables one not only to discover such fields and measure their spectrum but also to determine the ratios of their coupling strengths to the subatomic particles—electrons, neutrons, and protons. We further show that the multifaceted capabilities of this probe can be demonstrated with synthetic exotic fields generated by a combination of regular magnetic fields and light-induced fictitious magnetic fields in alkali atoms. These synthetic fields also enable the accurate calibration of any magnetometer or comagnetometer probe for exotic physics.

In this study, we revisit the extraction of parton-to-$K_S^0$ hadron fragmentation functions, named FF24-$K_S^0$, focusing on both next-to-leading-order and next-to-next-to-leading-order accuracy in perturbative QCD. Our approach involves the analysis of single inclusive electron-positron annihilation (SIA) data. The two key improvements are, on the one hand, the incorporation of the latest experimental data from the BESIII experiment and, on the other hand, the adoption of neural networks in the fitting procedure. To address experimental uncertainties, the Monte Carlo method is employed. Our investigation also explores the impact of hadron mass corrections on the description of SIA data, spanning a broad kinematic regime with a particular emphasis on the range of small $z$ values. The theory prediction for $K_S^0$ production at both NLO and NNLO accuracy exhibits good agreement with experimental data within their respective uncertainties.

Critical phenomena in phase transitions of strongly interacting matter, governed by quantum chromodynamics, are inherently encoded in the fluctuations of conserved charges. In this work, we study the net-baryon number density fluctuations, including the lowest-lying nucleon and the baryonic resonance $\mathrm{\Delta }(1232)$, based on the parity doublet model in the mean-field approximation. We focus on the qualitative features of the second-order susceptibility of the net-baryon number density in dense hadronic matter and how the inclusion of $\mathrm{\Delta }(1232)$ affects it. We demonstrate that the fluctuations of the individual baryons do not necessarily reflect the total net-baryon number fluctuations at finite density, due to the nontrivial correlations between different particle species. Our results highlight the role of baryonic correlations in the interpretation of data from heavy ion collision experiments.

The Forward Search Experiment (FASER) at CERN’s Large Hadron Collider (LHC) has recently directly detected the first collider neutrinos. Neutrinos play an important role in all FASER analyses, either as signal or background, and it is therefore essential to understand the neutrino event rates. In this study, we update previous simulations and present prescriptions for theoretical predictions of neutrino fluxes and cross sections, together with their associated uncertainties. With these results, we discuss the potential for possible measurements that could be carried out in the coming years with the FASER neutrino data to be collected in LHC Run 3 and Run 4.

Based on $(2.712\pm 0.014)\times {10}^9\psi (3686)$ events collected by the BESIII Collaboration, evidence of the hadronic decay $h_c\to K_S^0{K}^{+}{\pi }^{-}+\mathrm{c}.\mathrm{c}.$ is found with a significance of $4.3\sigma$ in the $\psi (3686)\to {\pi }^0{h}_c$ process. The branching fraction of $h_c\to K_S^0{K}^{+}{\pi }^{-}+\mathrm{c}.\mathrm{c}.$ is measured to be $(7.3\pm 1.8\pm 0.8)\times {10}^{-4}$, where the first and second uncertainties are statistical and systematic, respectively. Combining with the exclusive decay width of ${\eta }_c\to K\overline{K}\pi$, our result indicates inconsistencies with both pQCD and NRQCD predictions.

In the framework of the convolutional double copy, we investigate the asymptotic symmetries of the gravitational multiplet stemming from the residual symmetries of its single-copy constituents at null infinity. We show that the asymptotic symmetries of Maxwell fields in $D=4$ imply “double-copy supertranslations”, i.e., BMS supertranslations and two-form asymptotic symmetries, together with the existence of infinitely many conserved charges involving the double-copy scalar. With the vector fields in Lorenz gauge, the double-copy parameters display a radial expansion involving logarithmic subleading terms, essential for the corresponding charges to be nonvanishing.

We present a detailed description of a quantum scalar field theory within a flat spacetime confined to a cavity with perfectly reflecting moving boundaries. Moreover, we establish an equivalence between this time-dependent setting and a field theory on an acoustic metric with static Dirichlet boundary conditions. We discuss the classical and quantum aspects of the theory from the latter perspective, accompanied by the introduction of novel numerical techniques designed for the (nonperturbative) computation of particle production attributed to the dynamical Casimir effect, applicable to arbitrary boundary trajectories. As an illustrative example of these methodologies, we compute the particle production for a massless field in $1+1$ dimensions. Notably, our approaches readily extend to encompass scenarios involving massive fields and higher dimensions.

We investigate the hypothesis that sexaquarks, hypothetical stable six-quark states, could be a significant component of the dark matter. We expand on previous studies of sexaquark cosmology, accounting for the possibility that some relevant interaction cross sections might be strongly suppressed below expectations based on dimensional analysis. We update direct-detection constraints on stable sexaquarks comprising a subdominant fraction of the dark matter, as well as limits on the annihilation of an antisexaquark component from Super-Kamiokande. We argue that the scenario where sexaquarks comprise a $\mathcal{O}(1)$ fraction of the dark matter would require either a suppression of $\mathcal{O}({10}^{-19})$ in sexaquark interactions with baryons, combined with a very high yield of net sexaquark number from the quark-hadron transition, or else a very strong suppression of the cross section for antisexaquark annihilation on nucleons ($24+$ orders of magnitude below the QCD scale). Independently, we find that a sexaquark component comprising more than $\mathcal{O}({10}^{-3})$ of the dark matter can be excluded from direct-detection bounds, unless its scattering cross section is severely suppressed compared to the expected scale of strong and even electromagnetic interactions.

It is shown that the acceleration of particles by a powerful relativistic jet associated with the activity of a supermassive black hole in the Galactic Center several million years ago may explain the observed cosmic ray spectrum at energies higher than ${10}^{15}\mathrm{eV}$. The accelerated particles are efficiently confined in the extended magnetized gas halo created by the supernova and central black hole activity just after the formation of the Galaxy. We found that both the heavy and light chemical composition of ultrahigh energy cosmic rays can be consistent with observations.

In high multiplicity proton-proton ($p-p$) collisions, the formation of a deconfined state of quarks and gluons akin to heavy ion collisions (HIC) has been a subject of significant interest. In proton-proton ($p-p$) collisions, the transverse size of the system is comparable to the longitudinal (Lorentz contracted) dimension, unlike the case in a nucleus-nucleus ($A-A$) collision, leading to a hitherto unexplored effect of rapid decrease of temperature of the medium on quark-antiquark bound states. Starting with a bottom-up thermalization framework for preequilibrium stage, we model the hydrodynamic expansion of the resulting fireball based on the Gubser flow with both inviscid theory and viscous corrections up to the third order. We find that the temperature evolution in small systems is rather fast even with viscous evolution equations for energy density, thereby introducing sudden changes in the time evolution of the Hamiltonian. This scenario prompts the consideration of nonadiabatic evolution, justifying the need in the present case to go beyond the traditional adiabatic framework. We demonstrate that nonadiabatic evolution may suppress the dissociation of $J/\mathrm{\Psi }$ substantially in $p-p$ collisions, even at higher multiplicities, offering new insights into the dynamics of strongly interacting matter produced in smaller collision systems.

Vacuum polarization (VP) is investigated for the interaction of a polarized $\gamma$-ray beam of GeV photons with a counterpropagating ultraintense laser pulse. In a conventional setup of a vacuum birefringence measurement, a VP signal is the emerging small circular (linear) polarization of the initially linearly (circularly) polarized probe photons. The pair production via the nonlinear Breit-Wheeler process in such a high-energy environment eliminates part of the $\gamma$ photons in the outgoing $\gamma$ beam, increasing the statistical error and decreasing the accuracy of this VP signal. In contrast, we investigate the conversion of the emerging circular polarization of $\gamma$ photons into longitudinal polarization of the created positrons, considering the latter as the main VP signal. To study the VP effects in the highly nonlinear regime, where the Euler-Heisenberg effective Lagrangian method breaks down, we have developed a Monte Carlo simulation method, incorporating vacuum birefringence and dichroism via the one-loop QED probabilities in the locally constant field approximation. Our Monte Carlo method will enable the study of VP effects in strong fields of arbitrary configuration. With 10 PW laser systems, we demonstrate the feasibility of detecting the fermionic signal of the VP effect at the $5\sigma$ confidence level with a few hours of measurement time.

Using data samples with an integrated luminosity of $4.5{\mathrm{fb}}^{-1}$ collected by the BESIII detector at center-of-mass energies ranging from 4.66 GeV to 4.95 GeV, we study the processes of $e^{+}{e}^{-}\to \omega X(3872)$ and $e^{+}{e}^{-}\to \gamma X(3872)$. With the $e^{+}{e}^{-}\to \omega X(3872)$ process, the branching fraction ratio $R\equiv \frac{\mathcal{B}(X(3872)\to \gamma J/\psi )}{\mathcal{B}(X(3872)\to {\pi }^{+}{\pi }^{-}J/\psi )}$ is measured to be $0.38\pm 0.20_{\mathrm{stat}}\pm 0.01_{\mathrm{syst}}$ ($R<0.83$ at 90% confidence level). In addition, we measure the ratio of the average cross section of $e^{+}{e}^{-}\to \omega X(3872)$ to $e^{+}{e}^{-}\to \omega {\chi }_{c1}(\omega {\chi }_{c2})$ to be ${\sigma }_{\omega X(3872)}/{\sigma }_{\omega {\chi }_{c1}}({\sigma }_{\omega X(3872)}/{\sigma }_{\omega {\chi }_{c2}})=5.2\pm {1.0}_{\mathrm{stat}}\pm {1.9}_{\mathrm{syst}}(5.5\pm {1.1}_{\mathrm{stat}}\pm {2.4}_{\mathrm{syst}})$. Finally, we search for the process of $e^{+}{e}^{-}\to \gamma X(3872)$, and no obvious signal is observed. The upper limit on the ratio of the average cross section of $e^{+}{e}^{-}\to \gamma X(3872)$ to $e^{+}{e}^{-}\to \omega X(3872)$ is set as ${\sigma }_{\gamma X(3872)}/{\sigma }_{\omega X(3872)}<0.23$ at 90% confidence level.

Primordial black holes (PBHs), if trapped in neutron stars, emit a characteristic continuous, quasiperiodic gravitational wave (GW) signal as they orbit inside the host star. We identify a specific and qualitatively new feature of these signals, namely quasiperiodic beats caused by the precession of noncircular PBH orbits. We demonstrate numerically and analytically that the beat frequency depends rather sensitively on the neutron star structure, so that hypothetical future observations with next-generation GW detectors could provide valuable constraints on the nuclear equation of state.

In this work, we consider a general gravitational wave detector of gravitational waves interacting with an incoming gravitational wave carrying plus polarization only placed inside a harmonic trap. This model can be well acquainted with the description of a resonant detector of gravitational waves as well. The well-known detector-gravitational wave interaction scenario uses the method of a semiclassical approach where the detector is treated quantum mechanically but the gravitational wave is considered at a classical level. In our analysis, we use a discrete mode decomposition of the gravitational wave perturbation which results in a Hamiltonian involving the position and momentum operators corresponding to the gravitational wave and the harmonic oscillator. We have then calculated the transition probability for the harmonic oscillator-gravitational wave tensor product state for going from an initial state to some unknown final state. Using the energy flux relation of the gravitational waves, we observe that if we consider the total energy as a combination of the number of gravitons in the initial state of the detector then the transition probability for the resonant absorption case scenario takes the analytical form which is exactly similar to the semiclassical absorption case. In the case of the emission scenario, we observe a spontaneous emission of a single graviton which was completely absent in the semiclassical analog of this model. This therefore gives a direct signature of linearized quantum gravity.

Searching the data of gravitational-wave detectors for signals from compact binary mergers is a computationally demanding task. Recently, machine-learning algorithms have been proposed to address current and future challenges. However, the results of these publications often differ greatly due to differing choices in the evaluation procedure. The Machine Learning Gravitational-Wave Search Challenge was organized to resolve these issues and produce a unified framework for machine-learning search evaluation. Six teams submitted contributions, four of which are based on machine-learning methods, and two are state-of-the-art production analyses. This paper describes the submission from the team TPI FSU Jena and its updated variant. We also apply our algorithm to real O3b data and recover the relevant events of the GWTC-3 catalog.

Typical mechanisms to extract energies from a rotating black hole are the Blandford-Znajek process and the Penrose process. The Penrose process requires a special condition that is difficult to occur in common astrophysical situations. However, the magnetic Penrose process (MPP) does not require such a special condition, and can produce ultrahigh energy cosmic rays. When neutrons decay near a rotating black hole, the MPP efficiency of the produced proton is maximized. The supermassive black hole in Sagittarius A* (Sgr A*) is likely to have a radiatively inefficient accretion flow that is hot enough to produce neutrons by nuclear reactions, which can be subsequently accelerated to high-energy by the MPP. We calculate the production rate of accelerated protons from the Sgr A* to estimated the gamma-ray flux at Earth produced by these accelerated protons and the flux of the accelerated protons themselves transported from Sgr A* to Earth. We find that these very high-energy gamma rays ($E_{\gamma }\gtrsim 10\mathrm{TeV}$) amount to a significant fraction of the flux of the gamma ray from the HESS J1745-290 and the central molecular zone around 100 TeV. The accelerated proton flux, when the dimensionless spin parameter $a_{*}=0.5$ and the magnetic field strength in the vicinity of the black hole $B_0=100\mathrm{G}$, is about 1.6–4.1% of the cosmic ray proton flux from KASCADE experiment at about 1 PeV. Due to the finite decay time of neutrons that need to be transported from the accretion flow to the acceleration zone, our acceleration model can operate only around black holes with mass not much greater than $\sim {10}^8{M}_{\odot }$.

We compute the one-loop vertex function of the QCD coupling in the presence of an ultraintense magnetic field. From the vertex function, we extract the effective coupling and show that it grows with increasing magnetic field. We consider the quark-gluon vertex and the three-gluon vertex, accounting for the propagators of charged particles within the loops using the lowest Landau level approximation in order to satisfy the condition where the magnetic field is the largest energy scale. Under this approximation, we find that the contribution from the three-gluon vertex vanishes. Therefore, this result arises from the competition between the color charge associated to gluons and to quarks as well, with the former being larger than the latter. The behavior of the QCD coupling as a function of the magnetic field strength is analogous to that exhibited by the light-quark condensate, indicating the magnetic catalysis occurs. This increasing behavior stems from the dominant contribution of color charge associated to gluons in the vertex function.

We define a new strategy to scan jet substructure in heavy-ion collisions. The scope is multifold: (i) test the dominance of vacuum jet dynamics at early times, (ii) capture the transition from coherent to incoherent jet energy loss, and (iii) study elastic scatterings in the medium, which are either hard and perturbative or soft and responsible for jet thermalization. To achieve that, we analyze the angular distribution of the hardest splitting, ${\theta }_{\mathrm{hard}}$, above a transverse momentum scale, $k_t^{\min }$, in high-$p_t$ jets. Sufficiently high values of $k_t^{\min }$ target the regime in which the observable is uniquely determined by vacuumlike splittings and energy loss, leaving the jet substructure unmodified compared to proton-proton collisions. Decreasing $k_t^{\min }$ enhances the sensitivity to the relation between energy loss and the intrajet structure and, in particular, to observe signatures of color decoherence at small angles. At wider angles it also becomes sensitive to hard elastic scatterings with the medium and, therefore, the perturbative regime of medium response. Choosing $k_t^{\min }\approx 0$ leads to order one effects of nonperturbative origin such as hadronization and, potentially, soft scatterings responsible for jet thermalization. We perform a comprehensive analysis of this observable with three state-of-the-art jet-quenching Monte Carlo event generators. Our study paves the way for defining jet observables in heavy-ion collisions dominated by perturbative QCD and thus calculable from first principles.

NOvA is a long-baseline neutrino oscillation experiment that measures oscillations in charged-current ${\nu }_{\mu }\to {\nu }_{\mu }$ (disappearance) and ${\nu }_{\mu }\to {\nu }_e$ (appearance) channels, and their antineutrino counterparts, using neutrinos of energies around 2 GeV over a distance of 810 km. In this work we reanalyze the dataset first examined in our previous paper [Phys. Rev. D 106, 032004 (2022)] using an alternative statistical approach based on Bayesian Markov chain Monte Carlo. We measure oscillation parameters consistent with the previous results. We also extend our inferences to include the first NOvA measurements of the reactor mixing angle ${\theta }_{13}$, where we find $0.071\le {\sin }^{2}2{\theta }_{13}\le 0.107$, and the Jarlskog invariant, where we observe no significant preference for the $CP$-conserving value $J=0$ over values favoring $CP$ violation. We use these results to examine the effects of constraints from short-baseline measurements of ${\theta }_{13}$ using antineutrinos from nuclear reactors when making NOvA measurements of ${\theta }_{23}$. Our long-baseline measurement of ${\theta }_{13}$ is shown to be consistent with the reactor measurements, supporting the general applicability and robustness of the Pontecorvo-Maki-Nakagawa-Sakata framework for neutrino oscillations.

To address quantum computation of quantities in quantum chromodynamics (QCD) for which chiral symmetry is important, it would be useful to have the Hamiltonian for a fermion satisfying the Ginsparg-Wilson (GW) equation. I work with a solution to the GW equation which is fractional linear in time derivatives. The resulting Hamiltonian is nonlocal and has ghosts, but is free of doublers and has the correct continuum limit. This construction works in general odd spatial dimensions, and I provide an explicit expression for the Hamiltonian in one spatial dimension.