The average values of the powers of $\overline{|\overrightarrow{q}{|}^n}\equiv q^n$ and $\overline{|\overrightarrow{v}{|}^n}\equiv v^n$ are commonly used physical quantities, where $\overrightarrow{q}$ and $\overrightarrow{v}$ are the three-dimensional momentum and velocity of a quark inside a meson, respectively. For example, the average kinetic energy ${\mu }_{\pi }^2=q^2$ is an important quantity in the heavy quark effective theory, and the expansion of $v^n$ is commonly used in the nonrelativistic quantum chromodynamics. In this paper, based on the instantaneous Bethe-Salpeter equation method, we calculate the average values $q^n$ and $v^n$ ($n=1$, 2, 3, 4) of a heavy quark inside $S$ wave and $P$ wave heavy-light mesons. We obtain the kinetic energy ${\mu }_{\pi }^2=0.455{\mathrm{GeV}}^2$ for the $B$ meson, which is consistent with the experimental result $0.464\pm 0.076{\mathrm{GeV}}^2$. For the $B_s$, $D$, and $D_s$ mesons, the ${\mu }_{\pi }^2$ are 0.530, 0.317, and $0.369{\mathrm{GeV}}^2$, respectively, and $v^2=0.0185$, 0.0215, 0.121, and 0.140 for $B$, $B_s$, $D$, and $D_s$, respectively. We obtain some relationships, for example, $q_{0^{-}}^n(mS)\approx q_{1^{-}}^n(mS)$, $q_{0^{+}}^n(mP)\approx q_{1^{+\prime }}^n(m{P}^{\prime })>q_{1^{+}}^n(mP)\approx q_{2^{+}}^n(mP)$, and $q^n(mS)<q^n(mP)$ ($m=1$, 2, 3), etc.

We discuss a class of theories that predict a fermionic dark matter candidate from gauge anomaly cancellation. As an explicit example, we study the predictions in theories where the global symmetry associated with baryon number is promoted to a local gauge symmetry. In this context, the symmetry-breaking scale has to be below the multi-TeV scale in order to be in agreement with the cosmological constraints on the dark matter relic density. The new physical “Cucuyo” Higgs boson in the theory has very interesting properties, decaying mainly into two photons in the low mass region, and mainly into dark matter in the intermediate mass region. We study the most important signatures at the Large Hadron Collider, evaluating the experimental bounds. We discuss the correlation between the dark matter relic density, direct detection, and collider constraints. We find that these theories are still viable and are susceptible to being probed in current, and future high-luminosity, running.

Following previous works on that topic, we consider Euclidean hadronic matrix elements in position space of two spatially separated local currents on the lattice, in order to extract the $x$ dependence of parton distribution functions (PDFs). The corresponding approach is often referred to by the term lattice cross section. In this work we will consider valence quark PDFs of an unpolarized proton. We adapt the previously established formalism to our choice of operators. The calculation of the two-current matrix elements requires the evaluation of four-point functions. The corresponding calculation is carried out on a $n_f=2+1$ gauge ensemble with lattice spacing $a=0.0856\mathrm{fm}$ and pseudoscalar masses $m_{\pi }=355\mathrm{MeV}$ and $m_K=441\mathrm{MeV}$. The four-point functions have been evaluated in a previous project. The lattice data is converted to the $\overline{\mathrm{MS}}$ scheme at a scale $\mu =2\mathrm{GeV}$ and improved with respect to lattice artifacts. We use a common model as fit ansatz for the lattice data in order to extract the PDFs.

The refined Gribov-Zwanziger (RGZ) action in the Landau gauge provides a local and renormalizable framework to account for the existence of infinitesimal Gribov copies in the path integral together with other relevant infrared effects such as the formation of condensates. The properties of the tree-level gluon propagator obtained in this setup have been thoroughly investigated over the past decade. It accommodates important properties seen in lattice simulations such as a finite value at vanishing momentum and positivity violation. Yet a comprehensive study about the stability of such properties against quantum corrections was lacking. In this work, we compute the gluon propagator in the RGZ scenario at one-loop order and implement an appropriate renormalization scheme in order to compare our findings with lattice data. Remarkably, the qualitative properties of the tree-level gluon propagator are preserved. In particular, the fits with lattice data show evidence for positivity violation and the existence of complex poles for SU(2) and SU(3) gauge groups. We comment on the results for the ghost propagator as well.

We present a projection study for the first moments of the inclusive spin structure function $\int g_1(x,Q^2)dx$ for the proton and neutron from simulated doubly-polarized $\overrightarrow{e}\overrightarrow{p}$ and $\overrightarrow{e}\text{−}\overrightarrow{{}^3\mathrm{He}}$ collision data expected from the Electron Ion Collider. For detection and extraction of the neutron spin asymmetries from $\overrightarrow{e}\text{−}\overrightarrow{{}^3\mathrm{He}}$ collisions, we used the double-tagging method which significantly reduces the uncertainty over the traditional inclusive method. Using the Bjorken Sum Rule, the projected results allow us to determine that the QCD coupling at the $Z$-pole ${\alpha }_s(M_{Z^0}^2)$ can be measured with a relative precision of 1.3%. This underscores the significance of the EIC for achieving precision determinations of ${\alpha }_s$.

We study the thermodynamics of the heavy quarkonium and string breaking in the anisotropic media by gravity/gauge duality. The degree of anisotropy is characterized by the dynamical exponent $\nu$, with $\nu =1$ representing the isotropic case. The free energy of the heavy quarkonium, which is obtained through the Wilson loop, is investigated in an anisotropic background. It is found that the free energy is suppressed by the dynamical exponent $\nu$. The results also show that the anisotropy induced by anisotropic pressure significantly influences the free energy of the Coulombic part, in contrast to the effect of anisotropy induced by the magnetic field. Additionally, we find that when $\nu$ increases, both the absolute value of the imaginary potential and the thermal width increase. Finally, the string breaking is investigated in the confinement phase which corresponds to the zero temperature. It is found that the heavy meson is easier to decay in the presence of anisotropy compared to the isotropic case for the decay mode $Q\overline{Q}\to Q\overline{q}+\overline{Q}q$.

Using the diabatic formalism, which generalizes the adiabatic approximation in the Born-Oppen-heimer formalism, we apply well-known Hamiltonian methods to calculate the effect of open di-meson thresholds that lie well below the mass of elementary $c\overline{c}q{\overline{q}}^{\prime }$, $c\overline{c}s\overline{s}$, and $c\overline{c}q\overline{s}$ tetraquark bound states. We compute the resulting mass shifts for these states, as well as their decay widths to the corresponding meson pairs. Each mass eigenstate, originally produced using a bound-state approximation under the diabatic formalism, consists of an admixture of a compact diquark-antidiquark configuration (an eigenstate of the original dynamical diquark model) with an extended di-meson configuration induced by the nearest threshold. We compare our results with those from our recent work that employs a scattering formalism, and find a great deal of agreement, but also comment upon interesting discrepancies between the two approaches.

The resummation calculation (resbos) is a widely used tool for the simulation of single vector boson production at colliders. In this work, we develop a significant improvement over the resbos code by increasing the accuracy from $\mathrm{NNLL}+\mathrm{NLO}$ to ${\mathrm{N}}^3\mathrm{LL}+\mathrm{NNLO}$ and release the resbos v2.0 code. Furthermore, we propose a new nonperturbative function that includes information about the rapidity of the system (IFY). The IFY functional form was fitted to data from fixed target experiments, the Tevatron, and the LHC. We find that the nonperturbative function has mild rapidity dependence based on the results of the fit.

A sample of $pp$ collision data, corresponding to an integrated luminosity of $5.5{\mathrm{fb}}^{-1}$ and collected by the LHCb experiment during LHC Run 2, is used to measure the ratio of the lifetime of the ${\mathrm{\Xi }}_b^{-}$ baryon to that of the ${\mathrm{\Lambda }}_b^0$ baryon, $r_{\tau }\equiv {\tau }_{{\mathrm{\Xi }}_b^{-}}/{\tau }_{{\mathrm{\Lambda }}_b^0}$. The value $r_{\tau }=1.076\pm 0.013\pm 0.006$ is obtained, where the first uncertainty is statistical and the second systematic. This value is averaged with the corresponding value from Run 1 to obtain $r_{\tau }^{\mathrm{Run}1,2}=1.078\pm 0.012\pm 0.007$. Multiplying by the world-average value of the ${\mathrm{\Lambda }}_b^0$ lifetime yields ${\tau }_{{\mathrm{\Xi }}_b^{-}}^{\mathrm{Run}1,2}=1.578\pm 0.018\pm 0.010\pm 0.011\mathrm{ps}$, where the uncertainties are statistical, systematic, and due to the limited knowledge of the ${\mathrm{\Lambda }}_b^0$ lifetime. This measurement improves the precision of the current world average of the ${\mathrm{\Xi }}_b^{-}$ lifetime by about a factor of 2, and is in good agreement with the most recent theoretical predictions.

In this work, we explore the quantum theories of the free massive scalar, the massive fermionic, and the electromagnetic fields in a doubly special relativity scenario. This construction is based on a geometrical interpretation of the kinematics of this kind of theory. In order to describe the modified actions, we find that a higher (indeed infinite) derivative field theory is needed, from which the deformed kinematics can be read. From our construction, we are able to restrict the possible models of doubly special relativity to those that preserve linear Lorentz invariance. We quantize the theories and also obtain a deformed version of the Maxwell equations. We analyze the electromagnetic vector potential for both an electric pointlike source and magnetic dipole. We observe that the electric and magnetic fields do not diverge at the origin for some models described with an anti–de Sitter momentum space, but they do for a de Sitter space in both problems.

It is well known that the expansion of the universe can create particles. However, due to ambiguities when defining particles during the expansion, there are still debates about how to choose vacuum and particle states. To clarify how particles are produced in an expanding universe, we study the creation of real scalar particles in flat Friedmann-Lemaître-Robertson-Walker spacetimes by using a recently developed equal-time Wigner formalism. By comparing this quantum kinetic formalism with the standard Bogoliubov approach, we make a natural definition of a particle number in terms of kinetic phase-space functions, which we then compare with common adiabatic particle numbers. With inspiration from flat spacetime QED, we perform numerical calculations and discuss the interpretation of the particle numbers in terms of a hypothetical switch-off in the expansion rate. Finally, we consider how this interpretation is affected by regularization.

It is a hot topic nowadays that magnetic reconnection, as a physical process to release magnetic energy effectively, occurs in numerous complicated astrophysical systems. Since the magnetic reconnection is thought to occur frequently in the accretion flow around compact objects which induce strong gravitational field, it is now regarded to be a practical mechanism to extract energy from rotation black holes, which motivates people to consider how to describe the process of magnetic reconnection in a generally relativistic way. In this work, I try to explore the description of Sweet-Parker model, one of the most famous theoretical models of magnetic reconnection, in general relativity. I begin with revisiting the Sweet-Parker model in special relativity and reorganize the calculations in seven steps, whose generally relativistic forms are discussed. I propose in this work, from the general discussions and consequences of specific examples, that no property in Sweet-Parker model would be modified by spacetime curvature, which is opposite to the conclusions in previous work. However, on the contrary, observation in different rest frames may bring modifications. If the magnetic reconnection occurs not in the rest frame of observer, the observer would find out that the detected relation between the reconnection rate and Lundquist number or that between outflow speed and Alfvén velocity are not the same as the detected relations if the magnetic reconnection occurs just in the rest frame of observer.

Quantum black holes (BHs), thought of as an excited multilevel system, can be effectively modelled by replacing an event horizon with a partially reflective membrane. This emergent feature affects their interaction with hosting environments, with the most pronounced effects happening for particles with mass $m_{\mathrm{p}}\lesssim (10M_{\odot }/M){10}^{-11}\mathrm{eV}$, where $M$ is the BH mass. We show that ultralight bosons—a viable dark matter candidate—can be used to probe the quantum nature of BHs. We derive analytical expressions for the accretion rate and dynamical friction acting on exotic compact objects moving through an ultralight scalar field, finding that while the accretion rate is sensitive to the quantum BH’s reflectivity, the dynamical friction is the same as for classical BHs. We then use these expressions to estimate the orbital dephasing in the inspiraling of different binaries in the Laser Interferometer Space Antenna (LISA) band. Our results indicate that LISA may be able to discriminate quantum from classical BHs through their different accretion rates.

We analyze numerically the dynamical transition to spontaneous scalarization in neutron stars in the framework of a scalar-tensor theory of gravity where the scalar field is free but massive, and it is coupled nonminimally to gravity in the Jordan frame. We show that the quasistatic configuration of the star that settles after the transition can avoid the observational constraints imposed on the amount of scalarization by several observations in binary systems due to the presence of the mass term, which suppresses the range of the scalar field. We also study the impact of the scalar field mass on the gravitational mass of the star relative to the massless scenario.

We explore interstellar light transmission facilitated by gravitational lensing, focusing on axially symmetric lensing configurations where the transmitter, lens, and receiver are nearly aligned. Positioning an optical transmitter in the lens’s focal region, we investigate the caustic formed by a diffraction-limited annular beam of light emitted by the transmitter. We analyze the impact of the lens’s point spread function (PSF) on the projected beam’s structure, estimate the power delivered to a receiver at interstellar distances, and assess the major noise sources. We determine detection sensitivity in both noise- and signal-dominated regimes. Considering realistic assumptions about the transmitter’s performance, we explore signal detection strategies enhanced by the spatial broadening of the received beam, a result of the transmitting lens’s PSF. Our findings indicate that detecting lensed optical signals from nearby stars is achievable using established optical engineering technologies. A network of spatially distributed astronomical facilities capable of observations in multiple narrow spectral bands will enhance the search. Our results support the feasibility of interstellar power transmission via gravitational lensing, directly contributing to ongoing optical search for extraterrestrial intelligence efforts.

Primordial magnetogenesis is an intriguing possibility to explain the origin of intergalactic magnetic fields (IGMFs). However, the baryon isocurvature problem has recently been pointed out, ruling out all magnetogenesis models operating above the electroweak scale. In this paper, we show that lower-scale inflationary scenarios with a Chern-Simons coupling can evade this problem. We propose concrete inflationary models whose reheating temperatures are lower than the electroweak scale and numerically compute the amount of magnetic fields generated during inflation and reheating. We find that, for lower reheating temperatures, the magnetic helicity decreases significantly. It is also possible to generate fully helical magnetic fields by modifying the inflaton potential. In both cases, the produced magnetic fields can be strong enough to explain the observed IGMFs, while avoiding the baryon isocurvature problem.

We analyze a long-lived hypermassive neutron star merger remnant (postmerger lifetime $>250\mathrm{ms}$) that has been obtained via large eddy simulations with a gradient subgrid-scale model. We find a clear helicoidal magnetic field structure that is governed by the toroidal component of the magnetic field. Although no jet emerges during the simulation time, we observe at late times a significant increase of the poloidal component of the magnetic field at all scales. We also compare with the results of several binary neutron star simulations with moderate resolution of 120 m, that are evolved up to 50 ms after the merger, which differ in terms of the initial topology and strength of the magnetic field. We find that the best choice is an isotropic small-scale magnetic field distribution that mimics the turbulent state that generically develops during the merger. This initial configuration reaches a closer agreement with our high-resolution simulation results than the purely dipolar large-scale fields that are commonly employed in these type of simulations. This provides a recipe to perform such simulations avoiding the computationally expensive grids required to faithfully capture the amplification of the magnetic field by Kelvin-Helmholtz instabilities.

In this work, we study the luminosity that results from the conversion of QCD axion particles into photons in the magnetic field of the plasma accreting onto black holes (BHs). For the luminosities to be large two conditions need to be met: (i) there are large numbers of axions in the primordial BH surroundings as a result of the so-called superradiant instability; (ii) there exists a point inside the accreting region where the plasma and axion masses are similar and there is resonant axion-photon conversion. For BHs accreting from the interstellar medium in our Galaxy, the above conditions require the black hole to have subsolar masses and we are therefore led to consider a population of primordial black holes (PBHs). In the conservative window, where we stay within the nonrelativistic behavior of the plasma and neglect the possibility of nonlinear enhancement via magnetic stimulation, the typical frequencies of the emitted photons lie on the low-radio band. We thus study the prospects for detection using the LOFAR telescope, assuming the PBH abundance to be close to the maximal allowed by observations. We find that for PBH and QCD axion with masses in the range ${10}^{-5}–{10}^{-4}{M}_{\odot }$ and $4\times {10}^{-8}$ and $4\times {10}^{-7}\mathrm{eV}$, respectively, the flux density emitted by the closest PBH, assuming it accretes from the warm ionized medium, can be detected at the LOFAR telescope. Coincidentally, the PBH mass range coincides with the range that would explain the microlensing events found in OGLE. This might further motivate a dedicated search of these signals in the LOFAR data and other radio telescopes.

Rapidly rotating and strongly magnetized protoneutron stars (PNSs) created in core-collapse supernovae can drive relativistic magnetized winds. Ions and neutrons can be coaccelerated while they remain coupled through elastic collisions. We investigate the nucleosynthesis and subsequent nuclear disintegration, and find that relativistic neutrons can be generated in such magnetized winds. Upon eventual decoupling, resulting inelastic collisions with ejecta lead to pion production, resulting in 0.1–10 GeV neutrinos. Following this scenario presented in Murase et al. [Quasithermal neutrinos from rotating protoneutron stars born during core collapse of massive stars, Phys. Rev. D, 89, 043012 (2014)], we numerically calculate the spectra and light curves of quasithermal neutrino emission. In the event of a Galactic supernova, $\sim 10–1000$ neutrino events could be detected with Hyper-Kamiokande, KM3Net-ORCA, and IceCube-Upgrade for PNSs with surface magnetic field $B_{\mathrm{dip}}\sim {10}^{13–15}\mathrm{G}$ and initial spin period $P_i\sim 1–30\mathrm{ms}$. Successful detection will enable us to study supernovae as multienergy neutrino sources and may provide clues to the roles of PNSs in diverse classes of transients.