With large volumes of data available at LHC, it was possible to study the multiplicity distributions. It is interesting as well to check how well event generators can describe the properties and the behavior of multiparticle production processes. In this paper, we analyze the oscillatory behavior of modified combinants in proton-proton collisions at a center of mass energy of 7 TeV.

Investigation into the applicability of the equivalence principle in quantum mechanics has taken many forms, with varying conclusions. Here, a dynamical semiclassical description of a wave packet in terms of its center of mass and higher quantum fluctuations is applied to the case of a quantum particle in gravitational free fall. The analysis provides an intuitive account of the origin of mass dependence in quantum-gravitational dynamics through an effective potential that enforces the uncertainty principle. This potential has two implications: (i) The lowest order quantum fluctuations encoding the width and spreading of the wave packet obey an uncertainty relation whose observance is mass dependent. (ii) In an inhomogeneous gravitational field tidal effects couple the center of mass motion to the quantum fluctuations. The combined effect results in a clear demonstration of how some conceptions of the weak equivalence principle, based on mass dependence, are violated. The size of this violation is within sensitivities of current Eötvös and clock-based return time experiments.

The horizon of a flat Friedmann-Robertson-Walker (FRW) universe is considered to be dynamic when the Hubble parameter $H$ and the Hubble radius $r_H$ vary with time, unlike for de Sitter universes. To clarify the thermodynamics on a dynamic horizon, the evolution of a dynamical Kodama-Hayward temperature and Bekenstein-Hawking entropy on the horizon of a flat FRW universe is examined in a $\mathrm{\Lambda }(t)$ model similar to time-varying $\mathrm{\Lambda }(t)$ cosmologies. The $\mathrm{\Lambda }(t)$ model includes both a power-law term proportional to $H^{\alpha }$ (where $\alpha$ is a free variable) and the equation of state parameter $w$, extending a previous analysis [N. Komatsu, Phys. Rev. D 100, 123545 (2019)]. Using the present model, a matter-dominated universe ($w=0$) and a radiation-dominated universe ($w=1/3$) are examined, setting $\alpha <2$. Both universes tend to approach de Sitter universes and satisfy the maximization of entropy in the last stage. The evolution of several parameters (such as the Bekenstein-Hawking entropy) is similar for both $w=0$ and $w=1/3$, though the dynamical temperature $T_H$ is different. In particular, $T_H$ is found to be constant when $w=1/3$ with $\alpha =1$, although $H$ and $r_H$ vary with time. To discuss this case, the specific conditions required for constant $T_H$ are examined. Applying the specific condition to the present model gives a cosmological model that can describe a universe at constant $T_H$, as if the dynamic horizon is in contact with a heat bath. The relaxation processes for the universe are also discussed.

We investigate the Minkowski ground state associated with a real massless scalar field as seen by an accelerated observer under the perspective of the de Broglie–Bohm quantum theory. We use the Schrödinger picture to obtain the wave functional associated with the Minkowski vacuum in Rindler coordinates, and we calculate the field trajectories through the Bohmian guidance equations. The Unruh temperature naturally emerges from the calculus of the average energy, but the Bohmian approach precisely distinguishes between its quantum and classical components, showing that they periodically interchange their roles as the dominant cause for the temperature effects, with abrupt jumps in the infrared regime. We also compute the power spectra, and we exhibit a very special Bohmian field configuration with remarkable physical properties.

We study the bulk viscosity of moderately hot and dense, neutrino-transparent relativistic $npe\mu$ matter arising from weak-interaction direct Urca processes. This work parallels our recent study of the bulk viscosity of $npe\mu$ matter with a trapped neutrino component. The nuclear matter is modeled in a relativistic density functional approach with two different parametrizations—DDME2 (which does not allow for the low-temperature direct-Urca process at any density) and NL3 (which allows for low-temperature direct-Urca process above a low-density threshold). We compute the equilibration rates of Urca processes of neutron decay and lepton capture, as well as the rate of the muon decay, and find that the muon decay process is subdominant to the Urca processes at temperatures $T\ge 3\mathrm{MeV}$ in the case of DDME2 model and $T\ge 1\mathrm{MeV}$ in the case of NL3 model. Thus, the Urca-process-driven bulk viscosity is computed with the assumption that pure leptonic reactions are frozen. As a result, the electronic and muonic Urca channels contribute to the bulk viscosity independently, and at certain densities, the bulk viscosity of $npe\mu$ matter shows instead of the standard one-peak (resonant) form a “flattened” shape. In the final step, we estimate the damping timescales of density oscillations by the bulk viscosity. We find that, e.g., at a typical oscillation frequency $f=1\mathrm{kHz}$, the damping of oscillations is most efficient at temperatures $3\le T\le 5\mathrm{MeV}$ and densities $n_B\le 2n_0$ where they can affect the evolution of the postmerger object.

Black hole-neutron star (BH-NS) mergers are expected to emit gravitational wave (GW) and electromagnetic (EM) counterparts when the NS is tidally disrupted or plunges into the BH. Recently, GW 200105 and GW200115 were claimed as originating in BH-NS mergers, even GW 200105 remains in debate. Several optical source candidates are reported to possible associate with the two GW events, but not confirmed yet. In this work, we assume that the BH is charged (the NS is naturally charged) and try to constrain the charge of the BH by using the possible associated EM emission from the charged BH and NS system working in the inspiral regime. We adopt electric and magnetic dipole radiations for the binaries which power a Poynting-flux-dominated outflow to accelerate electrons. Then, it produces the observed EM radiation via synchrotron radiation. We find that the conversion efficiency in the x-ray band is much higher than that of the ultraviolet, near-infrared, and radio bands. The estimated maximum charge-to-mass ratio (the charge for unit mass) of the BH is $1.12\times {10}^{-6}$ and $1.53\times {10}^{-6}$ esu for the binary systems of GW200105 and GW200115, respectively, if magnetic field strength $B_p\lesssim {10}^{16}\mathrm{G}$ and period $P>1\mathrm{ms}$ for the NS spin.

We explore the features of interpolating gauge for QCD. This gauge, defined by Doust and by Baulieu and Zwanziger, interpolates between Feynman gauge or Lorenz gauge and Coulomb gauge. We argue that it could be useful for defining the splitting functions for a parton shower beyond order ${\alpha }_{\mathrm{s}}$ or for defining the infrared subtraction terms for higher order perturbative calculations.

We classify the allowed structures of the discrete 1-form gauge sector in six-dimensional supergravity theories realized as F-theory compactifications. This provides upper bounds on the 1-form gauge factors ${\mathbb{Z}}_m$ and in particular demands each cyclic factor obey $m\le 6$. Our bounds correspond to the universal geometric constraints on the torsion subgroup of the Mordell-Weil group of elliptic Calabi-Yau threefolds. For any F-theory vacua with at least one tensor multiplet, we derive the constraints from the ${\mathbb{P}}^1$ fibration structure of the base twofold and identify their physical origin in terms of the worldsheet symmetry of the associated effective heterotic string. The bounds are also extended to the F-theory vacua with no tensor multiplets via a specific deformation of the theory followed by a small instanton transition, along which the 1-form gauge sector is not reduced. We envision that our geometric bounds can be promoted to a swampland constraint on any six-dimensional gravitational theories with minimal supersymmetry and also extend them to four-dimensional F-theory vacua.

We study the dynamics of 2D chiral $SU(N)$ gauge theories with fermions in the symmetric, antisymmetric, and fundamental representations. A consistent infrared limit of these theories consists of certain coset conformal field theories. There is also a free-fermion phase which shares the same central charge and ’t Hooft anomalies but does not coincide with the coset models. We show that these two theories sit on a conformal manifold of infrared theories and are related by a current-current deformation. We further consider extensions of these theories by adding Dirac fermions and comment on possible renormalization group flows.

We consider the background of a rotating axially symmetric black hole. Let particle 0 decay to two fragments 1 and 2 in the direction parallel to that of particle 0. It is shown that if decay occurs inside the ergoregion, both particles 1 and 2 move in the same direction as particle 0. For the scenario, when decay happens in the turning point of all three particles, we find the condition when angular momenta of both particles 1 and 2 have the same sign. We elucidate the relation between the approach of Wald that imposes constraint on maximum and minimum energies of fragments and our approach. In doing so, we express the results in terms of characteristics of particle 0 and all particle masses. The conditions of the maximum efficiency depending on the relation between masses is discussed. We find an explicit expression for angular momenta of particles 1 and 2. We discuss also particle decay for static black holes, when the Penrose process is impossible. Because of the absence of the ergoregion in the static case, scenarios of decay for static black holes can significantly differ from those in the rotating background.

We derive from first principles equations for nonrelativistic bosonic, self-interacting dark matter which can include both a condensed, low momentum “fuzzy” component and one with higher momenta that may be approximated as a collection of particles. The resulting coupled equations consist of a modified Gross-Pitaevskii equation describing the condensate and a kinetic equation describing the higher momentum modes, the “particles,” along with the Poisson equation for the gravitational potential sourced by the density of both components. Our derivation utilizes the Schwinger-Keldysh path integral formalism and applies a semiclassical approximation which can also accommodate collisional terms amongst the particles and between the particles and the condensate to second order in the self-coupling strength. The equations can therefore describe both cold dark matter and fuzzy dark matter in a unified way, allowing for the coexistence of both phases and the inclusion of quartic self-interactions.

Axionlike particles (ALPs), which are very light neutral spin zero elusive particles primarily interacting with two photons and predicted by superstring and superbrane theories, have come to help by solving two distinct problems about blazars (a type of active galactic nuclei), thus providing two hints at the existence of ALPs themselves. In the presence of an external magnetic field, ALPs produce (i) photon-ALP oscillations and (ii) the change of the polarization state of photons. The former effect has many consequences in the astrophysical contest, such as the modification of the transparency of the Universe and the alteration of the astrophysical spectra. We address here the latter effect by analyzing how the photon degree of linear polarization and the polarization angle get modified by the photon-ALP interaction in the case where photons are generated at the jet base of some BL Lacs (a blazar class): OJ 287, BL Lacertae, Markarian 501 and 1ES $0229+200$, by considering both a leptonic and hadronic emission mechanism. We show that OJ 287 and BL Lacertae are good observational targets for ALP studies both in the x-ray band with IXPE (already operative) and with the proposed eXTP, XL-Calibur, NGXP and XPP missions, and in the high-energy range with the COSI, e-ASTROGAM and AMEGO missions, while 1ES $0229+200$ represents a strong candidate in the x-ray band only. Since these blazars show a very high final photon degree of linear polarization—which cannot be explained by conventional physics—such a possible detection would represent an additional hint at the ALP existence. Instead, Markarian 501 does not appear as a good target for these studies. We conclude that all these observatories can give us additional fundamental information about ALP physics.

The population of binary black hole mergers observed in gravitational waves, together with astrophysical simulations, can help us to understand the properties of the progenitors and the binary formation mechanisms in different astrophysical scenarios. Here we focus on dynamical formation in star clusters. We use the third gravitational-wave transient catalog (GWTC-3) and rapster, a rapid code to simulate cluster dynamics, to show that it is possible to construct the single-event likelihood of star cluster properties from individual observations. We find that the measured primary mass in a binary black hole merger correlates with the measured star cluster mass, because the mass spectrum of the primary component increases with the mass of the cluster. This trend may be caused by two physical mechanisms: (i) the more efficient production of hierarchical mergers with primary mass above $\sim 40M_{\odot }$ for cluster masses of $\gtrsim {10}^6{M}_{\odot }$, and (ii) the suppression of more massive first-generation binaries, which happens because ejected binaries do not merge within the lookback time for cluster masses of $\lesssim {10}^5{M}_{\odot }$. The formalism presented here can be generalized to infer the population properties of binary progenitors in more realistic scenarios involving multiple formation channels.

Kerr black holes radiate neutrinos in an asymmetric pattern, preferentially in the lower hemisphere relative to the black hole’s rotation axis, while antineutrinos are predominantly produced in the upper hemisphere. Leveraging this asymmetric emission, we explore the potential of high energy, $E_{\nu }\gtrsim 1\mathrm{TeV}$, neutrino, and antineutrino detection to reveal crucial characteristics of an evaporating primordial black hole at the time of its burst when observed near Earth. We improve upon previous calculations by carefully accounting for the nonisotropic particle emission, as Earth occupies a privileged angle relative to the black hole’s rotation axis. Additionally, we investigate the angular dependence of primary and secondary photon spectra and assess the evaporating black hole’s time evolution during the final explosive stages of its lifetime. Since photon events outnumber neutrinos by about three orders of magnitude, we find that a neutrino measurement can aid in identifying the initial angular momentum and the black hole hemisphere facing Earth only for evaporating black holes within our solar system, at distances $\lesssim {10}^{-4}\mathrm{pc}$, and observed during the final 100 s of their lifetime.

We investigate a family of four-dimensional quantum field theories with weakly interacting ultraviolet fixed points up to four-loop order in perturbation theory. Key new ingredients are the three-loop gauge contributions to quartic scalar beta functions, which we compute in the $\overline{\mathrm{MS}}$ scheme for a template $SU(N_c)$ gauge theory coupled to $N_f$ fundamental fermions and elementary scalars. We then determine fixed point couplings, field and mass anomalous dimensions, and universal scaling exponents up to the first three nontrivial orders in a small Veneziano parameter. The phase diagram and UV-IR connecting trajectories are found and contrasted with asymptotic freedom. Further, the size of the conformal window, unitarity, and mechanisms leading to the loss of conformality are investigated. Our results provide blueprints for concrete four-dimensional nonsupersymmetric conformal field theories with standard model-like field content and invite further model building.

Muon neutrino and antineutrino disappearance probabilities are identical in the standard three-flavor neutrino oscillation framework, but $CPT$ violation and nonstandard interactions can violate this symmetry. In this work we report the measurements of ${\sin }^2{\theta }_{23}$ and $\mathrm{\Delta }{m}_{32}^2$ independently for neutrinos and antineutrinos. The aforementioned symmetry violation would manifest as an inconsistency in the neutrino and antineutrino oscillation parameters. The analysis discussed here uses a total of $1.97\times {10}^{21}$ and $1.63\times {10}^{21}$ protons on target taken with a neutrino and antineutrino beam respectively, and benefits from improved flux and cross section models, new near-detector samples and more than double the data reducing the overall uncertainty of the result. No significant deviation is observed, consistent with the standard neutrino oscillation picture.

We use lattice simulations and the continuous renormalization group method, based on the gradient flow, to calculate the $\beta$ function and anomalous dimensions of the SU(3) gauge theory with $N_f=10$ flavors of fermions in the fundamental representation. We employ several improvements to extend the range of available renormalized couplings, including the addition of heavy Pauli-Villars bosons to reduce cutoff effects and the combination of a range of gradient flow transformations. While in the weak coupling regime our result is consistent with those of earlier studies, our techniques allow us to study the system at much stronger couplings than previously possible. We find that the renormalization group $\beta$ function develops a zero, corresponding to an infrared-stable fixed point, at gradient-flow coupling $g^2=15.0(5)$. We also determine the mass and tensor anomalous dimensions: At the fixed point we find ${\gamma }_m\simeq 0.6$, suggesting that this system might be deep inside the conformal window.