We propose a new numerical method for $3+1$-dimensional glasma simulation using Milne coordinates. We formulate the classical Yang-Mills field and three-dimensional classical color current on a lattice at the initial proper time, specified as a moment just before the collision of the two nuclei. By solving the evolution equations, we extract observables of the three-dimensional glasma at later times. We demonstrate the efficiency of our method in terms of numerical cost and apply it to the central collisions of Au-Au. We also discuss possible further improvements of our method.

The baryon-number violation (BV) happens in the standard electroweak model. According to the Bloch-wave picture, the BV event rate shall be significantly enhanced when the proton-proton collision center of mass (COM) energy goes beyond the sphaleron barrier height $E_{\mathrm{sph}}\simeq 9.0\mathrm{TeV}$. Here we compare the BV event rates at different COM energies, using the Bloch-wave band structure and the CT18 parton distribution function data, with the phase space suppression factor included. As an example, the BV cross section at 25 TeV is 4 orders of magnitude bigger than its cross section at 13 TeV. The probability of detection is further enhanced at higher energies since an event at higher energy will produce on average more same sign charged leptons.

We present the conceptual design and the physics potential of darksphere, a proposed 3 m in diameter spherical proportional counter electroformed underground at the Boulby Underground Laboratory. This effort builds on the R&D performed and experience acquired by the NEWS-G Collaboration. darksphere is primarily designed to search for nuclear recoils from light dark matter in the 0.05–10 GeV mass range. Electroforming the spherical shell and the implementation of a shield based on pure water ensures a background level below 0.01 dru. These, combined with the proposed helium-isobutane gas mixture, will provide sensitivity to the spin-independent nucleon cross section of $2\times {10}^{-41}$ $(2\times {10}^{-43}){\mathrm{cm}}^2$ for a dark matter mass of 0.1(1) GeV. The use of a hydrogen-rich gas mixture with a natural abundance of ${}^{13}\mathrm{C}$ provides sensitivity to spin-dependent nucleon cross sections more than two orders of magnitude below existing constraints for dark matter lighter than 1 GeV. The characteristics of the detector also make it suitable for searches of other dark matter signatures, including scattering of MeV-scale dark matter with electrons, and superheavy dark matter with masses around the Planck scale that leave extended ionization tracks in the detector.

New particles with large masses that decay into hadronically interacting particles are predicted by many models of physics beyond the Standard Model. A search for a massive resonance that decays into pairs of dijet resonances is performed using $140{\mathrm{fb}}^{-1}$ of proton-proton collisions at $\sqrt{s}=13\mathrm{TeV}$ recorded by the ATLAS detector during Run 2 of the Large Hadron Collider. Resonances are searched for in the invariant mass of the tetrajet system, and in the average invariant mass of the pair of dijet systems. A data-driven background estimate is obtained by fitting the tetrajet and dijet invariant mass distributions with a four-parameter dijet function and a search for local excesses from resonant production of dijet pairs is performed. No significant excess of events beyond the Standard Model expectation is observed, and upper limits are set on the production cross sections of new physics scenarios.

The ALICE Collaboration reports three measurements in ultraperipheral proton-lead collisions at forward rapidity. The exclusive two-photon process $\gamma \gamma \to {\mu }^{+}{\mu }^{-}$ and the exclusive photoproduction of $J/\psi$ are studied. $J/\psi$ photoproduction with proton dissociation is measured for the first time at a hadron collider. The cross section for the two-photon process of dimuons in the invariant mass range from 1 to $2.5\mathrm{GeV}/c^2$ agrees with leading-order quantum electrodynamics calculations. The exclusive and dissociative cross sections for $J/\psi$ photoproductions are measured for photon-proton center-of-mass energies from 27 to 57 GeV. They are in good agreement with HERA results.

In Starobinsky inflation with a Weyl squared Lagrangian $-\alpha C^2$, where $\alpha$ is a coupling constant, we study the linear stability of cosmological perturbations on a spatially flat Friedmann-Lemaître-Robertson-Walker background. In this theory, there are two dynamical vector modes propagating as ghosts for $\alpha >0$. This condition is required to avoid tachyonic instabilities of vector perturbations during inflation. The tensor sector has four propagating degrees of freedom, among which two of them correspond to ghost modes. However, the tensor perturbations approach constants after the Hubble radius crossing during inflation, and hence the classical instabilities are absent. In the scalar sector, the Weyl curvature gives rise to a ghost mode coupled to the scalaron arising from the squared Ricci scalar. We show that two gauge-invariant gravitational potentials, which are both dynamical in our theory, are subject to exponential growth after the Hubble radius crossing. There are particular gauge-invariant combinations like the curvature perturbations whose growth is suppressed, but it is not possible to remove the instability of other propagating degrees of freedom present in the perturbed metric. This violent and purely classical instability present in the scalar sector makes the background unviable. Furthermore, the presence of such classical instability makes the quantization of the modes irrelevant, and the homogeneous inflationary background is spoiled by the Weyl curvature term.

We present the first systematic search for exotic compact mergers in Advanced LIGO and Virgo events. We compare the short gravitational-wave signals GW190521, GW190426_190642, GW200220_061928, and the trigger 200114_020818 (or S200114f) to a new catalog of 759 numerical simulations of head-on mergers of horizonless exotic compact objects known as Proca stars, interpreted as self-gravitating lumps of (fuzzy) dark matter sourced by an ultralight (vector) bosonic particle. The Proca star merger hypothesis is strongly rejected with respect to the black hole merger one by GW190426, weakly rejected by GW200220 and weakly favored by GW190521 and S200114f. GW190521 and GW200220 yield highly consistent boson masses of ${\mu }_{\mathrm{B}}=8.69_{-0.75}^{+0.61}\times {10}^{-13}\mathrm{eV}$ and ${\mu }_{\mathrm{B}}=9.13_{-1.30}^{+1.18}\times {10}^{-13}\mathrm{eV}$ at the 90% credible level. We conduct a preliminary population study of the compact binaries behind these events. Excluding (including) S200114f as a real event, and ignoring boson-mass consistencies across events, we estimate a fraction of Proca star mergers of $\zeta =0.27_{-0.25}^{+0.43}(0.39_{-0.33}^{+0.38})$. We discuss the impact of boson-mass consistency across events in such estimates. Our results maintain GW190521 as a Proca star merger candidate and pave the way toward population studies considering exotic compact objects.

Accurate noise estimation from gravitational wave GW data is critical for Bayesian inference. However, recent studies on ringdown signal, such as those by Isi et al. [Phys. Rev. Lett. 127, 011103 (2021)], Cotesta et al. [Phys. Rev. Lett. 129, 111102 (2022)], and Isi and Farr [arXiv:2202.02941], have encountered disagreement in noise estimation, leading to inconsistent results. The key discrepancy between these studies lies in the usage of different noise estimation methods, augmented by the usage of different sampling rates. We achieved consistent results across various sampling rates by correctly managing noise estimation, shown in the case study of the GW150914 ringdown signal. By conducting a time-domain Bayesian inference analysis on GW data, starting from the peak of the signal, we discovered that the first overtone mode is weakly supported by the amplitude distribution, with a confidence level of $1.6\sigma$, and is slightly disfavored by the log-Bayes factor. Overall, in our time-domain analysis we conclude there is no strong evidence for overtones in GW150914.

We investigate the phenomenology of the dark $Z$ boson, $Z_d$, which is associated with a new Abelian gauge symmetry and couples to the standard model particles via kinetic mixing $ϵ$ and mass mixing ${ϵ}_Z$. We examine two cases: (i) $Z_d$ is lighter than the $Z$ boson, and (ii) $Z_d$ is heavier than that. In the first case, it is known that $Z_d$ causes a deviation in the weak mixing angle at low energies from the standard model prediction. We study the prediction in the model and compare it with the latest experimental data. In the second case, the $Z\text{−}{Z}_d$ mixing enhances the $W$ boson mass. We investigate the effect of $Z_d$ on various electroweak observables including the $W$ boson mass using the $S$, $T$, and $U$ parameters. We point out an interesting feature: in the limit $ϵ\to 0$, the equation $S=-U$ holds independently of the mass of $Z_d$ and the size of ${ϵ}_Z$, while $|S|\gg |U|$ in many new physics models. We find that the dark $Z$ boson with a mass of $\mathcal{O}(100)\mathrm{GeV}$ with a relatively large mass mixing can reproduce the CDF result within $2\sigma$ while avoiding all other experimental constraints. Such dark $Z$ bosons are expected to be tested at future high-energy colliders.

A number of extensions of the Standard Model predict the existence of new light, weakly coupled particles that couple to the visible sector through higher-dimensional operators containing one or two photons, suppressed by a high new physics scale, and thus have long lifetimes. In this work, we study the prospects for detecting three $\sim \mathrm{sub}\text{-\hspace{0.17em}\hspace{0.17em}}\mathrm{GeV}$ such long-lived particles (LLP) at intensity frontier experiments: a massive spin-2 mediator ($G$), a dark axion portal, and a light neutralino coupled to ALPino or gravitino. We consider the production and visible decays of these particles in several current and proposed beam dump experiments (CHARM, NuCal, SeaQuest, NA62, SHiP) as well as in the LHC detectors (FASER, $\mathrm{FASER}\nu$, FLArE, MATHUSLA). In addition to the usual displaced vertex signature, we also examine the impact of electron scattering signature and the Primakoff-like process which leads to conversion of $G$ into a photon or to the secondary LLP production via upscattering of the lighter dark sector state on dense material put in front of the detector. In all cases, we find the SHiP experiment could provide the strongest constraints for the displaced vertex search, while FASER2/FPF could provide complementary coverage of the $\gamma c\tau \sim 1\mathrm{m}$ decay length region of the parameter space.

We study the observable implications of an incomplete first order phase transition during inflation. In such a phase transition, the nucleated bubbles do not percolate and instead are continuously produced until the onset of reheating. The process creates an inhomogeneity with a distinct power spectrum that depends on both the physics of the phase transition and the inflationary dynamics. Upon horizon reentry, this spectrum generates gravitational waves through nonlinear effects. This stochastic gravitational wave background is predicted to have unique signatures that may be detectable by future experiments spanning a wide frequency range. The discovery of such a gravitational wave signal would shed a light on the detailed dynamics of inflation.

We examine the production of an invisible state $X$ together with a photon, $e^{+}{e}^{-}\to \gamma +X$, at electron positron colliders and present measurement strategies that can detect the spin of the invisible state as well as the underlying production mechanism, based on the angular distribution of the final-state photon, the cross sections for polarized initial states, and the photon polarization. Our measurement strategy can be used to identify whether the invisible state is a hidden photon or an axion. The results are compared with a detailed analysis of the Standard Model background, and we calculate the sensitivity reach for searches for axions and hidden photons at Belle II.

Staple-shaped Wilson line operators are necessary for the study of transverse momentum-dependent parton distribution functions (TMDPDFs) in lattice QCD and beyond. In this work, we study the renormalization of such operators in the general case of an asymmetric staple. We analyze the mixing pattern of these operators using their symmetry properties, where we find that the possible mixing is restricted within groups of four operators. We then present numerical results using the regularization independent momentum subtraction (RI/MOM) scheme to study the importance of mixing using one operator in particular, the ${\gamma }_0$ operator. Based on these results, we consider the short distance ratio (SDR) scheme, which is desirable in the absence of mixing. Finally, we investigate a variant of the RI/MOM scheme, where the renormalization factors are computed at short distances.

Nonlinearities in the dispersion relations associated with different interactions designs, boundary conditions, and the existence of a physical cutoff scale can alter the quantum vacuum energy of a nonrelativistic system nontrivially. As a material realization of this, we consider a one-dimensional-periodic rotating, interacting nonrelativistic setup. The quantum vacuum energy of such a system is expected to comprise two contributions: a fluctuation-induced quantum contribution and a repulsive centrifugal-like term. We analyze the problem in detail within a complex Schödinger quantum field theory with a quartic interaction potential and perform the calculations nonperturbatively in the interaction strength by exploiting the nonlinear structure of the associated nonlinear Schrödinger equation. Calculations are done both in zeta-regularization as well as by introducing a cutoff scale. We find a generic, regularization-independent behavior, where the competition between the interaction and rotation can be balanced at some critical ring size, where the quantum vacuum energy has a maximum and the force changes sign. The inclusion of a cutoff smoothes out the vacuum energy at small distance but leaves unaltered the long-distance behavior. We discuss how this behavior can be tested with ultracold atoms.

One of the greatest challenges in quantum chromodynamics is understanding the hadronization mechanism, which is also crucial for carrying out precision physics with jet substructure. In this paper, we bring together recent advancements in our understanding of nonperturbative structure of the soft drop jet mass based on field theory, with precise perturbative calculations at next-to-next-to-leading logarithmic accuracy of its multidifferential variants. This allows for a model-independent analysis of power corrections associated with hadronization in a systematic manner. We test and calibrate hadronization models and their interplay with parton showers by comparing our universality predictions with various event generators for quark and gluon initiated jets in both lepton-lepton and hadron-hadron collisions. Our findings reveal that hadronization models perform better for quark jets relative to gluon jets. Our results provide a valuable toolbox for precision studies with the soft drop jet mass and pave the way for future analyses using real-world collider data. The stringent constraints derived in our framework are useful for improving the modeling of hadronization and its interplay with parton showers in next-generation event generators.

Understanding axial charge dynamics driven by changes in Chern-Simons number densities is a key aspect in understanding the chiral magnetic effect in heavy-ion collisions. Most phenomenological simulations assume that a large amount of axial charge is produced in the initial stages and that axial charge is conserved throughout the simulation. Within an (expanding) homogeneous holographic plasma, we investigate the real-time axial charge relaxation dynamics and their impact on the chiral magnetic current. Moreover, we discuss the real-time interplay of the non-Abelian and the Abelian chiral anomaly in the presence of a strong magnetic field. In the expanding plasma, the Chern-Simons diffusion rate and thus the axial charge relaxation rate are time dependent due to the decaying magnetic field. We quantify the changes in the late time falloffs and establish a horizon formula for the chiral magnetic current.

Pulsars are rapidly rotating neutron stars emitting intense electromagnetic radiation that is detected on Earth as regular and precisely timed pulses. By exploiting their extreme regularity and comparing the real arrival times with a theoretical model (pulsar timing), it is possible to deduce many physical properties, concerning not only the neutron star and its possible companion, but also the properties of the interstellar medium as well as tests of general relativity. In light of recent works according to which dark energy may have an astrophysical origin, in this paper we investigate the effect of “matter” on the propagation time delay of photons emitted by a pulsar orbiting a spinning black hole using the rotational Kiselev metric. We deduce an analytical formula for the time delay from geodesic equations, showing how it changes as the type of matter around the black hole (radiation, dust or dark energy) varies with respect to previous results, where matter has not been taken into account. It turns out that while the spin $a$ only induces a shift in the phase of the maximum delay without increasing or decreasing the delay, the effect of matter surrounding the black hole results in a noticeable alteration of it. Our results show that dark energy would give the strongest effect and that, interestingly, when the pulsar is positioned between the observer and the black hole a slightly lower pulse delay than in the no-matter case appears. Alterations are practically imperceptible in the case of pure radiation.

The Einstein-Æther theory is an alternative theory of gravity in which the spacetime metric is supplemented by a long-range timelike vector field (the “aether” field). Here, for the first time, we apply the full formalism of post-Minkowskian theory and of the direct integration of the relaxed Einstein equations (DIRE), to this theory of gravity, with the goal of deriving equations of motion and gravitational waveforms for orbiting compact bodies to high orders in a post-Newtonian expansion. Because the aether field is constrained to have unit norm, a naive application of post-Minkowskian theory leads to contributions to the effective energy momentum tensor that are linear in the perturbative fields. We show that a suitable redefinition of fields using an array of “superpotentials” can eliminate such linear terms to any desired post-Newtonian order, resulting in flat spacetime wave equations for all fields, with sources consisting of matter terms and terms quadratic and higher in the fields. As an initial application of this new method, and as a foundation for obtaining the equations of motion for compact binaries, we obtain explicit solutions of the relaxed equations sufficient to obtain the metric in the near zone through 2.5 post-Newtonian order, or $O[(v/c{)}^5]$ beyond the Newtonian approximation.

A new, exact and analytical class of accelerating and charged black holes is built, in the Einstein-Maxwell theory, thanks to the Harrison transformation. The diagonal metric does not belong to the Petrov type D classification, therefore it is not part of the Plebanski-Demianski spacetimes. The simplest subcase of this family recovers the Reissner-Nordstrom black hole in the vanishing acceleration limit and the standard C-metric in the limit of null electric charge. More general cases can have two independent electric charges, which can be tuned as desired, even to remain with an uncharged black hole, such as Petrov type I Schwarzschild, embedded in an accelerating charged Rindler background. These accelerating black holes can be considered as a limit of charged binary systems. Conical singularities can be possibly removed in extremal configurations. The entropy of the conformal field theory model dual to the extreme black hole is obtained from near horizon analysis. Magnetic, dyonic, NUTty and Kerr-like extensions are also discussed.