The dynamics of the electroweak phase transition in the early Universe has profound implications for cosmology and particle physics. We systematically study the steady-state dynamics of bubble walls in scenarios where the transition is first order within three representative beyond the Standard Model frameworks, characterized by the presence of an additional scalar in different electroweak representations. Focusing on the local thermal equilibrium regime, we numerically solve the coupled scalar and hydrodynamic equations to extract key properties of the phase transition front: the wall velocity, width, plasma, and field profiles. We find a near-universal behavior across models when expressed in terms of thermodynamic quantities, which can be captured by simple fitting functions, useful for phenomenological applications. These results also provide an upper bound on the bubble velocity and represent the first necessary step for the full inclusion of out-of-equilibrium effects. As an application, we determine the gravitational wave signal and the amount of baryon asymmetry generated by the transition in local thermal equilibrium.

In this work, we study the contribution of invisible light particles to ${\mathrm{\Lambda }}_b\to \mathrm{\Lambda }{E}_{\mathrm{miss}}$, particularly the three-body decays ${\mathrm{\Lambda }}_b\to \mathrm{\Lambda }\varphi \overline{\varphi }$ and ${\mathrm{\Lambda }}_b\to \mathrm{\Lambda }\psi \overline{\psi }$. The differential branching ratio of ${\mathrm{\Lambda }}_b\to \mathrm{\Lambda }{E}_{\mathrm{miss}}$ and the $q^2$-dependent longitudinal polarization asymmetry of $\mathrm{\Lambda }$ in scenarios explaining the Belle II excess are presented. In the chiral basis, we investigate the correlations between $\mathcal{B}(B\to K{E}_{\mathrm{miss}})$ and $\mathcal{B}({\mathrm{\Lambda }}_b\to \mathrm{\Lambda }{E}_{\mathrm{miss}})$, as well as between $\mathcal{B}(B\to K{E}_{\mathrm{miss}})$ and $P_L^{\mathrm{\Lambda }}$, in eight distinct new physics scenarios. We find that the $P_L^{\mathrm{\Lambda }}$ can be used to distinguish the chirality of the hadronic current part in the effective operators, which is similar to the cases in the two-body decays ${\mathrm{\Lambda }}_b\to \mathrm{\Lambda }\varphi$ and ${\mathrm{\Lambda }}_b\to \mathrm{\Lambda }V$.

Building upon the recent findings regarding inverse phase transitions in the early Universe, we present the first natural realization of this phenomenon within a supersymmetry-breaking sector. We demonstrate that inverse hydrodynamics, which is characterized by the fluid being sucked by the bubble wall rather than being pushed or dragged, is actually not limited to a phase of (re)heating but can also occur within the standard cooling cosmology. Through a numerical analysis of the phase transition, we establish a simple and generic criterion to determine its hydrodynamics based on the generalized pseudotrace. Our results provide a proof of principle highlighting the need to account for these new fluid solutions when considering cosmological phase transitions and their phenomenological implications.

We investigate the role of vector boson fusion (VBF) and associated production with an electroweak boson ($V$-AP) of beyond-the-Standard-Model Higgs bosons at the LHC in probing $CP$ violation in extended Higgs sectors. Resonant production of a new Higgs boson through $V$-AP and VBF subsequently decaying into a $Z$ boson and a 125 GeV Higgs boson $h$ would be a robust sign of $CP$ violation, since $h$ has been measured to be (predominantly) a $CP$-even state. After identifying this and other sets of signatures which rely on $V$-AP and VBF to jointly uncover $CP$ violation, we analyze the prospects to measure $CP$ violation in this way for the complex two-Higgs-doublet model at the High-Luminosity LHC.

We study a scenario where the Standard Model is extended by a SU(2) gauge group in the dark sector. The three associated dark gauge bosons are stabilized via a custodial symmetry triggered by an additional dark SU(2) scalar doublet, thus making them viable dark-matter candidates. After considering the most recent constraints for this model, we analyze the phase transition dynamics and compute the power spectrum of the resulting stochastic gravitational-wave background. Finally, we find regions of the parameter space yielding the observed dark-matter relic density while also leading to a strong enough phase transition with an associated gravitational-wave signal reaching the sensitivity of a future space-based gravitational-wave detector, such as LISA, DECIGO, BBO, TianQin, or Taiji.

We investigate the twisted Eguchi-Kawai (TEK) reduced model of four-dimensional $SU(N)$ gauge theory in the presence of two-flavor adjoint fermions (adjoint TEK model). Using Monte Carlo simulations with $N=121$, twist parameter $k=1$, hopping parameter $\kappa =0.01–0.03$ ($\ll {\kappa }_c$) and inverse ’t Hooft coupling $b=0.30–0.45$, we show that heavy adjoint fermions stabilize the $({\mathbb{Z}}_N{)}^4$ center-symmetric vacuum even for the minimal twist satisfying $k/\sqrt{N}<1/9$, where the $({\mathbb{Z}}_N{)}^4$ symmetry is spontaneously broken in the absence of adjoint fermions. This result also suggests that the adjoint TEK model with the minimal twist is equivalent to $SU(N)$ gauge theory over a broader $(\kappa ,b)$ parameter region than the adjoint EK model without twist. We further extend our analysis to a partially reduced model to realize a geometry akin to ${\mathbb{R}}^3\times S^1$ and study the theory under $S^1$ compactification with periodic adjoint fermions. Numerical simulations with $N=16–49$, $b=0.30–0.46$, and $\kappa =0.03–0.16$ are consistent with the adiabatic continuity conjecture; with periodic adjoint fermions, the theory remains in a center-symmetric (confined) phase as the $S^1$ circle size is reduced, in contrast to the deconfining transition observed in the pure TEK model or in the TEK model with antiperiodic adjoint fermions. We present the Polyakov loop measurements and consistency checks supporting these findings.

We investigate the emergence of thermalization in a quantum-field-theoretic model mimicking the production of jets in QCD: the massive lattice Schwinger model coupled to external sources. Specifically, we compute the expectation values of local operators as functions of time and compare them to their thermal counterparts, quantify the overlap between the evolving density matrix and the thermal one, and compare the dynamics of the energy-momentum tensor to predictions from relativistic hydrodynamics. Through these studies, we find that the system approaches thermalization at late times and elucidate the mechanisms by which quantum entanglement drives thermalization in closed field-theoretic systems. Our results show how thermodynamic behavior emerges in real time from unitary quantum dynamics.

We perform a global QCD analysis of unpolarized parton distribution functions (PDFs) in the proton, including new $W+\mathrm{charm}$ production data from $pp$ collisions at the LHC and semi-inclusive pion and kaon production data in lepton-nucleon deep-inelastic scattering, both of which have been suggested for constraining the strange quark PDF. Compared with a baseline global fit that does not include these datasets, the new analysis reduces the uncertainty on the strange quark distribution over the range $0.01<x<0.3$, and provides a consistent description of processes sensitive to strangeness in the proton. Including the new datasets, the ratio of strange to nonstrange sea quark distributions is $R_s=(s+\overline{s})/(\overline{u}+\overline{d})=\{0.72_{-0.34}^{+0.52},0.46_{-0.20}^{+0.30},0.32_{-0.15}^{+0.23}\}$ for $x=\{0.01,0.04,0.1\}$ at $Q^2=4{\mathrm{GeV}}^2$. The data place more stringent constraints on the strange asymmetry $s-\overline{s}$, which is found to be consistent with zero in this range.

A calculation of the two-particle two-hole contribution to the semi-inclusive $({\nu }_{\mu },{\mu }^{-}N)$ cross section on carbon is performed in the framework of the relativistic Fermi gas model. The process is driven by meson-exchange currents encompassing all contributions involving the exchange of a single pion and the excitation of a $\mathrm{\Delta }$ resonance. The calculation is validated against the inclusive $({\nu }_{\mu },{\mu }^{-})$ response functions already existing in the literature, and then extended for the first time to the semi-inclusive channel. Results are presented both at fixed neutrino energy and folded with the T2K neutrino flux.

We searched for bound neutron decay via $n\to \overline{\nu }+K^0$ predicted by the grand unified theories in $0.401\mathrm{Mton}·\mathrm{years}$ exposure of all pure water phases in the Super-Kamiokande detector. About 4.4 times more data than in the previous search have been analyzed by a new method including a spectrum fit to kaon invariant mass distributions. No significant data excess has been observed in the signal regions. As a result of this analysis, we set a lower limit of $7.8\times {10}^{32}\mathrm{years}$ on the neutron lifetime at a 90% confidence level.

An amplitude analysis of the ${\mathrm{\Xi }}_c^{+}\to p{K}^{-}{\pi }^{+}$ decay together with a measurement of the ${\mathrm{\Xi }}_c^{+}$ polarization vector in semileptonic beauty-hadron decays is presented. The analysis is performed using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of $9{\mathrm{fb}}^{-1}$. An amplitude model is developed and the resonance fractions as well as two- and three-body decay parameters are reported. A sizeable ${\mathrm{\Xi }}_c^{+}$ polarization is found. A large sensitivity of the ${\mathrm{\Xi }}_c^{+}\to p{K}^{-}{\pi }^{+}$ decay to the polarization is seen, making the amplitude model suitable for ${\mathrm{\Xi }}_c^{+}$ polarization measurements in other systems.

A signal consistent with the $\mathrm{\Omega }(2012)$ baryon has been observed with a significance of $15\sigma$ in pp collisions at $\sqrt{s}=13\mathrm{TeV}$ at the LHC. In this paper, the analysis technique is described and measurements of the mass and width of the $\mathrm{\Omega }(2012)$ are reported, along with the first measurement of its transverse-momentum spectrum and yield. This paper corroborates the observation by the Belle Collaboration of this excited $\mathrm{\Omega }$ state and the observation that the $\mathrm{\Omega }(2012)$ has a rather narrow width for a strongly decaying resonance. The yield measurement is combined with a statistical thermal model calculation of strange baryon yield ratios to obtain estimates of the $\mathrm{\Omega }(2012{)}^{-}\to \mathrm{\Xi }\overline{\mathrm{K}}$ branching ratios. These results will improve our understanding of the internal structure and mass spectrum of excited baryon states and serve as a baseline for searches regarding modifications of these properties in high-temperature media.

A search for events with one displaced vertex from long-lived particles using data collected by the ATLAS detector at the Large Hadron Collider is presented, using $140{\mathrm{fb}}^{-1}$ of proton-proton collision data at $\sqrt{s}=13\mathrm{TeV}$ recorded in 2015–2018. The search employs techniques for reconstructing vertices of long-lived particles decaying into hadronic jets in the muon spectrometer displaced between 3 m and 14 m from the primary interaction vertex. The observed number of events is consistent with the expected background and limits for several benchmark signals are determined. A scalar-portal model and a Higgs-boson-portal baryogenesis model are considered. A dedicated analysis channel is employed to target Z-boson associated long-lived particle production, including an axionlike particle and a dark photon model. For the Higgs boson model, branching fractions above 1% are excluded at 95% confidence level for long-lived particle proper decay lengths ranging from 5 cm to 40 m. For the photophobic axionlike particle model considered, this search produces the strongest limits to date for proper decay lengths greater than $\mathcal{O}(10)\mathrm{cm}$.

We show that two- and three-pion states produced in the decay of neutral kaons are contextual, entangled, and Bell nonlocal in isospin space. By reinterpreting the experimental values of the different isospin amplitudes, we can determine the amount of entanglement enjoyed by these states and the extent to which they violate the noncontextuality and Bell locality inequalities. Notably, the two-pion case provides an example of a state that is more Bell nonlocal, as witnessed by the Collins-Gisin-Linden-Massar-Popescu inequality, than the maximally entangled one. The three-pion state offers a genuine multipartite test of Bell nonlocality with qutrits. This is the first instance where quantum properties like entanglement and contextuality are demonstrated to exist within the internal space of isospin.

We study the proposed integrable spin chain formulation of Jordanian deformations of the ${\mathrm{AdS}}_5\times S^5$ superstring, realized via Drinfel’d twists. Among these models, we first identify a unique supergravity deformation confined to an $SL(2,\mathbb{R})$ sector and with constant dilaton. We then develop a general framework for closed Drinfel’d twisted spin chains and construct an explicit map to undeformed models with twisted-boundary conditions. Applied to the noncompact ${\mathrm{XXX}}_{-1/2}$ spin chain, the Jordanian twist breaks the Cartan generator labeling magnon excitations, obstructing the standard Bethe methods. Instead, using the twisted-boundary formulation, we initiate the spectral problem based on a residual root generator both in the continuum limit and for short chains. We find that the ground state is nontrivially deformed, and is in agreement with the classical string result, while our analysis does not capture higher-spin excited states. We also study the asymptotics of the associated $Q$ system, which is well behaved and compatible with the boundary twist. While a full understanding of the spectrum remains open, our work provides concrete steps toward a spectral description of non-Abelian twisted integrable models.

The relation between covariant fracton gauge theory and Møller-Hayashi-Shirafuji theory of gravity is investigated. The former is the gauge theory of a rank-two symmetric tensor with gauge symmetry given by the double derivative of a scalar parameter; the latter is the most general theory, whose action is quadratic in the Weitzenböck torsion. We show that the solutions of covariant fracton gauge theory describe a subsector of the space of solutions of Møller-Hayashi-Shirafuji theory, providing a new insight in the relation between covariant fractons and gravity, and elucidating the meaning of covariant fracton theory as a new type of gauge theory.

The classification of the unitary irreducible representations of symmetry groups is a cornerstone of modern quantum physics, as it provides the fundamental building blocks for constructing the Hilbert spaces of theories admitting these symmetries. In the context of gravitational theories, several arguments point toward the existence of a universal symmetry group associated with corners, whose structure is the same for every diffeomorphism-invariant theory in any dimension. Recently, the representations of the maximal central extension of this group in the two-dimensional case have been classified using purely algebraic techniques. In this work, we present a complementary and independent derivation based on Kirillov’s orbit method. We study the coadjoint orbits of the group $\widetilde{\mathrm{SL}(2,\mathbb{R})}⋉{\mathbb{H}}_3$, where ${\mathbb{H}}_3$ is the Heisenberg group of a quantum particle in one dimension. Our main result is that, despite the non-Abelian nature of the normal subgroup in the semidirect product, these orbits admit a simple description. In a coordinate system associated with modified Lie algebra generators, the orbits factorize into a product of coadjoint orbits of $\mathrm{SL}(2,\mathbb{R})$ and ${\mathbb{H}}_3$. The subsequent geometric quantization of these factorized orbits successfully reproduces the known representations.

Recently it has been shown that the third law of black hole mechanics can be violated; an exactly extremal Reissner-Nordström black hole can form in finite time in gravitational collapse of matter with a large charge to mass ratio. However, it has also been proved that this cannot happen if the matter satisfies a “supersymmetric” lower bound on its energy in terms of its charge. This paper proves an analogous result for black holes with a negative cosmological constant. The result states that a supersymmetric Kerr-Newman-anti–de Sitter black hole cannot form in gravitational collapse of charged matter satisfying the supersymmetric bound. The results for zero or negative cosmological constant are extended to apply to two-sided black holes; it is proved that an initially nonextremal black hole cannot evolve to a supersymmetric black hole in finite time, irrespective of whether or not the initial black hole was formed in gravitational collapse.

Amazingly, recent studies indicate that nonlinear effects are of great significance for modeling black hole ringdown. Transient electromagnetic events in the astrophysical environment are typically high energetic, potentially responsible for some nonlinearities in ringdown. Motivated by the desire to understand these nonlinearities, we solve the inhomogeneous Bardeen-Press-Teukolsky equation numerically and find second-order gravitational tails induced by an electromagnetic source. Our results suggest that the second-order tails of curvature perturbations with multipole numbers $l\ge 4$ decay as $t^{-2l-2}$ at fixed spatial position and $u^{-l-3}$ in retarded-time $u$ at null infinity, slower than their linear counterparts, which can play a role in multimessenger observations.

We present a comprehensive assessment of multiparameter tests of general relativity (GR) in the inspiral regime of compact binary coalescences using principal component analysis (PCA). Our analysis is based on an extensive set of simulated gravitational-wave (GW) signals, including both general relativistic and non-GR sources, injected into zero-noise data colored by the noise power spectral densities of the LIGO and Virgo GW detectors at their designed sensitivities. We evaluate the performance of PCA-based methods in the context of two established frameworks: TIGER and FTI. For GR-consistent signals, we find that PCA enables stringent constraints on potential deviations from GR, even in the presence of multiple free parameters. Applying the method to simulated signals that explicitly violate GR, we demonstrate that PCA is effective at identifying such deviations. We further test the method using numerical relativity waveforms of eccentric binary black hole systems and show that missing physical effects—such as orbital eccentricity—can lead to apparent violations of GR if not properly included in the waveform models used for analysis. Finally, we apply our PCA-based test to selected real gravitational-wave events from GWTC-3, including GW190814 and GW190412. We present joint constraints from selected binary black hole events in GWTC-3, finding that the 90% credible bound on the most informative PCA parameter is ${0.03}_{-0.08}^{+0.08}$ in the TIGER framework and $-0.01_{-0.04}^{+0.05}$ in the FTI framework, both of which are consistent with GR. These results highlight the sensitivity and robustness of the PCA-based approach and demonstrate its readiness for application to future observational data from the fourth observing runs of LIGO, Virgo, and KAGRA.