We model the effect of resonances between time-varying perturbative forces and the epicyclical motion of eccentric binaries in the gravitational wave (GW) driven regime. These induce secular drifts in the orbital elements, which are reflected in a dephasing of the binary’s GW signal, derived here systematically. The resulting dephasing prescriptions showcase a much richer phenomenology with respect to typically adopted models and are better able to model realistic environmental effects. The most important consequences are for gas embedded binaries, which we analyze in detail with a series of analytical calculations, numerical experiments, and a curated set of hydrodynamical simulations for equal masses. Even in these simplified tests, we find the surprising result that dephasing caused by epicyclical resonances dominate over expectations based on smoothed or orbit averaged gas drag models in GW signals that retain mild eccentricity in the detector band ($e>0.05$). We discuss how dissecting GW dephasing in its component Fourier modes can be used to probe the coupling of binaries with their surrounding environment in unprecedented detail.

The three Standard Model neutrinos can have Majorana mass or strictly Dirac mass, but both scenarios are practically indistinguishable in neutrino oscillation experiments. If they are pseudo-Dirac, however, there will be new mass splittings among the pseudo-Dirac pairs, potentially leaving traces in neutrino oscillation phenomena. In this work, we use flavor ratios of astrophysical neutrinos to discriminate different possible mass spectra of pseudo-Dirac neutrinos. We show that it will be possible to impose robust bounds of order $\delta m_3^2\lesssim {10}^{-12}{\mathrm{eV}}^2$ on the new mass squared splitting involving the third pseudo-Dirac mass eigenstates (those with the least electron flavor composition) with the future experiment IceCube-Gen2. The derived sensitivity is robust because it only assumes an extragalactic origin for the astrophysical neutrinos and hierarchical pseudo-Dirac mass spectrum. In case the neutrino sources are known in the future, such bounds can potentially improve by up to five orders of magnitude, reaching $\delta m_3^2\lesssim {10}^{-17}{\mathrm{eV}}^2$.

We investigate the $O(N)$-symmetric ${\varphi }^6$ theory in three spacetime dimensions using dimensional regularization and minimal subtraction. The predictions of other methods are scrutinized in a large-$N$ expansion. We show how the tricritical line of fixed point emerges in a strict $N\to \infty$ limit but argue that it is not a physical manifestation. For the first time in this explicit manner, we compute the effective potential at next-to-leading order in the $1/N$-expansion and discuss its stability. The Bardeen-Moshe-Bander phenomenon is also analysed at next-to-leading order, and we demonstrate that it disappears without breaking the scale invariance spontaneously. Our findings indicate that the UV fixed point found by Pisarski persists at large $N$.

We study resonant production of pairs of Standard Model (SM-)like Higgs bosons, in the presence of new neutral Higgs states together with new colored scalars (stops or sbottoms) in loops within the Next-to-Minimal Supersymmetric Standard Model. This is used as a test case to prove that the Large Hadron Collider has sensitivity to a variety of effects stemming from interferences between resonant (heavy) Higgs diagrams and/or among these and nonresonant topologies involving loops of both tops and stops. These effects can alter significantly the naive description of individual $s$-channel Breit-Wigner resonances, leading to distortions of the latter, which, on the one hand, may mask their presence but, on the other hand, could enable one to extract features of the underlying new physics scenario. This last aspect is made possible through a decomposition of the $gg\to hh$ signal process into all its amplitude components, each of which has a well-defined coupling structure. Ultimately, such effects can be traced back to the relevant Feynman diagrams and can enable a detailed interpretation of this process. To illustrate this, we introduce various benchmark points that exhibit potentially observable features during the current and/or upcoming runs of the LHC in one or more of the three customary di-Higgs decay channels: $b\overline{b}b\overline{b}$, $b\overline{b}{\tau }^{+}{\tau }^{-}$, and $b\overline{b}\gamma \gamma$.

Fifth force and equivalence principle tests search for new interactions by precisely measuring forces between macroscopic collections of atoms and molecules and their properties under free fall. In contrast, the early Universe plasma probes these interactions at a more fundamental level. In this paper, we consider the case of a scalar mediating a fifth force, and show that the effects of dimensional transmutation, spontaneous symmetry breaking, and the running of the gauge couplings cause the scalar’s low-energy interactions to mix, leading to nearly universal dynamics at early times. We use known expressions for the pressure of the Standard Model during its various epochs to compute the scalar effective potential, and find that the cosmological dynamics of this scalar are very sensitive to the reheat temperature of the Universe. Given the unknown reheat temperature, we show that scalar couplings to matter larger than $\sim {10}^{-6}(m_{\varphi }/\mathrm{eV}{)}^{-1/4}$ relative to gravity produce the correct dark matter abundance, motivating new physics searches in this part of parameter space.

Mass and full width of the heavy scalar molecule $\mathcal{M}$ composed of the mesons $B_c^{+}$ and $B_c^{-}$ are calculated in the QCD sum rule framework. To find its mass and current coupling, we apply the two-point sum rule method. The width of the hadronic molecule $\mathcal{M}=B_c^{+}{B}_c^{-}$ is evaluated by taking into account its dissociation to ${\eta }_c{\eta }_b,J/\psi \mathrm{\Upsilon }$, and $B_c^{+}{B}_c^{-}$ mesons. Decays into $D$ and $B$ meson pairs with appropriate charges and quantum numbers triggered by $\overline{b}b$ and $\overline{c}c$ annihilations to light quark-antiquarks are also included in the analyses. Because the partial widths of $\mathcal{M}$ molecule’s decay channels depend on the strong couplings at $\mathcal{M}$-meson-meson vertices, we estimate them by invoking tools of the three-point sum rule method. Our predictions $m=(12725\pm 85)\mathrm{MeV}$ and $\mathrm{\Gamma }[\mathcal{M}]=(155\pm 23)\mathrm{MeV}$ for the parameters of the molecule $\mathcal{M}$ provide useful information for experimental studies of numerous heavy resonances.

Spontaneous symmetry breaking in quantum field theories at nonzero temperature still holds fundamental open questions, in particular what happens to vacuum Goldstone bosons when the temperature is increased. By investigating a complex scalar field theory on the lattice we demonstrate that Goldstone bosons at nonzero temperature behave like screened massless particlelike excitations, so-called thermoparticles, which continue to exist even in the symmetry-restored phase of the theory. We provide nonperturbative evidence for the functional form of the Goldstone mode’s dissipative behavior, and determine its corresponding spectral properties. Since the persistence of thermal Goldstone modes within symmetry-restored phases is predicted to be a model-independent characteristic, this has fundamental consequences for systems in which continuous symmetries are restored at high temperatures.

The Atacama Cosmology Telescope (ACT) has recently released new measurements and constraints on inflationary observables. In this paper, it is shown that a component of a dynamical affine connection, which is independent of the metric, can easily drive inflation in agreement with these observations. Such geometrical explanation of inflation is analyzed in detail here in the minimal model, including the predictions for the scalar spectral index $n_s$ and its running ${\alpha }_s$, the amplitude of the scalar perturbations, and the tensor-to-scalar ratio $r$. Furthermore, this minimal model is shown to provide an inflationary attractor: arbitrary initial values of the kinetic energy density are dynamically attracted down to negligible values compared to the potential energy density in homogeneous and isotropic metrics. Also, the role of the Higgs boson during and after inflation is briefly discussed.

Reissner-Nordström-anti–de Sitter (RNAdS) black holes in the extended phase space exhibit critical behavior analogous to the liquid-gas system, with critical exponents matching those of van der Waals-type phase transitions. However, the kinetics of these transitions near spinodal and critical points remain poorly understood. We demonstrate that both the autocorrelation time and the variance of trajectories increase significantly as the system approaches these special points, signaling critical slowing down. This behavior is driven by the flattening of the free energy landscape, as further confirmed by the lowest eigenvalue of the Fokker-Planck equation. Moreover, we uncover a clear dynamical crossover separating gaslike and liquidlike regimes in the supercritical region. This kinetic crossover defines the Widom line that closely matches the thermodynamic one obtained from the maxima of the isobaric heat capacity. These findings contribute to a deeper understanding of the kinetics of RNAdS black holes in the vicinity of spinodal and critical points.

We numerically analyze the behavior of a charged scalar field on a fixed extremal Reissner-Nordström background. We find an extension of the Aretakis instability characterized by an accumulation of charge on the extremal event horizon. In particular, when the electromagnetic coupling to the scalar field is sufficiently large, the charge density on the horizon asymptotes to a nonzero constant at late times. By constructing monochromatic initial data at the onset of charged superradiance, we give evidence supporting the claim that this instability is connected to the presence of a nearly zero-damped mode. Throughout this work, we employ a numerical integration scheme in compactified double-null coordinates, which allows us to capture the asymptotic behavior of the matter at the boundaries of the spacetime.

In this article, we revisit the thermodynamics of black holes endowed with primary and secondary scalar hair in the shift and ${\mathrm{Z}}_2$ symmetric subclass of beyond Horndeski gravity. Under a specific fine-tuning of the scalar parameter $q$ in terms of the black hole mass, the singular black hole solution with primary scalar hair reduces to the regular Bardeen solution featuring secondary scalar hair. We first demonstrate that the traditional thermodynamic approach fails to yield a consistent Smarr formula for both solutions under consideration. To address this issue, we adopt the approach introduced in [Phys. Rev. Lett. 132, 191401 (2024).], and we derive both the first law of black hole thermodynamics and the Smarr formula, offering a consistent thermodynamic description for scalar-hairy black holes. As an additional outcome, our analysis reveals a connection between singular and regular black hole solutions with primary and secondary scalar hair, respectively.

Self-interacting neutrinos provide an intriguing extension to the Standard Model, motivated by both particle physics and cosmology. Recent cosmological analyses suggest a bimodal posterior for the coupling strength $G_{\mathrm{eff}}$, favoring either strong or moderate interactions. These interactions modify the scale dependence of the growth of cosmic structures, leaving distinct imprints on the matter power spectrum at small scales, $k>0.1{\mathrm{Mpc}}^{-1}$. For the first time, we explore how the 21-cm power spectrum from the cosmic dawn and the dark ages can constrain the properties of self-interacting massive neutrinos. The effects of small-scale suppression and enhancement in the matter power spectrum caused by self-interacting neutrinos propagate to the halo mass function, shaping the abundance of small- and intermediate-mass halos. It is precisely these halos that host the galaxies responsible for driving the evolution of the 21-cm signal during the cosmic dawn. We find that Hydrogen Epoch of Reionization Array (HERA) at its design sensitivity can improve upon existing constraints on $G_{\mathrm{eff}}$ and be sensitive to small values of the coupling, beyond the reach of current and future cosmic microwave background (CMB) experiments. Crucially, we find that the combination of HERA and CMB-Stage 4 can break parameter degeneracies, significantly improving the sensitivity to $G_{\mathrm{eff}}$ over either experiment alone. Finally, we investigate the prospects of probing neutrino properties with futuristic Lunar interferometers, accessing the astrophysics-free 21-cm power spectrum during the dark ages. The capability of probing small scales of these instruments will allow us to reach a percent-level constraint on the neutrino self-coupling.

Fast neutrino flavor conversion may impact the explosion mechanism and nucleosynthesis in core-collapse supernovae. A necessary condition for fast flavor conversion is the presence of crossings in the angular distribution of the electron-neutrino lepton number (ELN) crossing. Because of the computational costs, flavor-dependent angular distributions are not computed by the vast majority of state-of-the-art hydrodynamical simulations; instead, angular distributions are reconstructed employing approximate methods in postprocessing. In this work, we evaluate the performance of four methods adopted to diagnose the existence of ELN crossings. For selected postbounce times, we extract the fluid and thermodynamic properties from spherically symmetric supernova simulations for an $18.6M_{\odot }$ progenitor, testing cases with and without muons as well as with and without mixing-length treatment of protoneutron star convection. We compare the occurrence of crossings in the angular distributions obtained by solving the Boltzmann equations with those in distributions reconstructed from angular moments of our Boltzmann solutions by using the maximum entropy and Minerbo schemes, and also with crossings identified via a polynomial weighting function applied to the angular moments. Our results show that the polynomial method and the Minerbo closure scheme have severe limitations. The maximum entropy approach captures most of the forward crossings, although it fails to reproduce or misidentifies crossings in a subset of our models. These findings highlight the need for robust modeling of the neutrino angular properties in order to assess the impact of flavor conversion on the supernova mechanism.

Phenomenological calculations of the properties of dense matter, such as relativistic mean-field theories, represent a pathway to predicting the microscopic and macroscopic properties of neutron stars. However, such theories do not generically have well-controlled uncertainties and may break down within neutron stars. To faithfully represent the uncertainty in this breakdown scale, we develop a hybrid representation of the dense-matter equation of state, which assumes the form of a relativistic mean-field theory at low densities, while remaining agnostic to any nuclear theory at high densities. To achieve this, we use a nonparametric equation of state model to incorporate the correlations of the underlying relativistic mean-field theory equation of state at low pressures and transition to more flexible correlations above some chosen pressure scale. We perform astrophysical inference under various choices of the transition pressure between the theory-informed and theory-agnostic models. We further study whether the chosen relativistic mean-field theory breaks down above some particular pressure and find no such evidence. Using simulated data for future astrophysical observations at about two-to-three times the precision of current constraints, we show that our method can identify the breakdown pressure associated with a potential strong phase transition.

Hawking radiation sets stringent constraints on primordial black holes (PBHs) as a dark matter candidate in the $M\sim {10}^{16}\mathrm{g}$ regime based on the evaporation products such as photons, electrons, and positrons. This motivates the need for rigorous modeling of the Hawking emission spectrum. Using semiclassical arguments, Page [Phys. Rev. D 16, 2402 (1977)] showed that the emission of electrons and positrons is altered due to the black hole acquiring an equal and opposite charge to the emitted particle. The Poisson fluctuations of emitted particles cause the charge $Z|e|$ to random walk, but since acquisition of charge increases the probability of the black hole emitting another charged particle of the same sign, the walk is biased toward $Z=0$, and $P(Z)$ approaches an equilibrium probability distribution with finite variance $⟨Z^2⟩$. This paper explores how this “stochastic charge” phenomenon arises from quantum electrodynamics (QED) on a Schwarzschild spacetime. We prove that (except for a small Fermi blocking term) the semiclassical variance $⟨Z^2⟩$ agrees with the variance of a quantum operator $⟨{\widehat{\mathcal{Z}}}^2⟩$, where $\widehat{\mathcal{Z}}$ may be thought of as an “atomic number” that includes the black hole as well as the charge near it (weighted by a factor of $2M/r$). In QED, the fluctuations in $\widehat{\mathcal{Z}}$ do not arise from the black hole itself (whose charge remains fixed), but rather as a collective effect in the Hawking-emitted particles mediated by the long-range electromagnetic interaction. We find the rms charge $⟨Z^2{⟩}^{1/2}$ asymptotes to 3.44 at small PBH masses $M\lesssim 2\times {10}^{16}\mathrm{g}$, declining to 2.42 at $M=5.2\times {10}^{17}\mathrm{g}$.

We analyze the damping of inflationary gravitational waves (GW) that re-enter the Hubble horizon before or during a post inflationary era dominated by a metastable right-handed neutrino (RHN), whose out-of-equilibrium decay releases entropy. Within a minimal type-I seesaw extension of the Standard Model, we explore the conditions under which the population of thermally produced RHNs remain long-lived and cause a period of matter domination. We find that the suppression of the GW spectrum occurs above a characteristic frequency determined by the RHN mass and active-sterile mixing. For RHN masses in the range 0.1–10 GeV and mixing ${10}^{-12}\lesssim |V_{eN}{|}^2\lesssim {10}^{-5}$, we estimate such characteristic frequencies and the signal-to-noise ratio to assess the detection prospects in GW observatories such as THEIA, $\mu$-ARES, LISA, BBO, and ET. Additionally we use LIGO data to put upper bounds on the reheating temperature after inflation, for a given blue-tilted GW spectrum. We find complementarity between GW signals and laboratory searches in SHiP, DUNE, and LEGEND-1000. Notably, RHN masses of 0.2–2 GeV and mixing ${10}^{-10}\lesssim |V_{eN}{|}^2\lesssim {10}^{-7}$ are testable in both laboratory experiments and GW observations. Additionally, GW experiments can probe the canonical seesaw regime of light neutrino mass generation, a region largely inaccessible to laboratory searches.

We develop a version of fluctuating relativistic hydrodynamics in a way very different from the usual derivation: Instead of treating it as a coarse-grained deterministic theory expanded in gradients of equilibrium quantities, we treat it as a stochastic theory, characterized by partition functions in each cells, expanded in cumulants. We show that the Gaussian ansatz allows us, via the gravitational Ward identities acting as a constraint between the variance and the average, to maintain full general covariance, with hydrodynamic flow emerging as an approximate Killing vector. If the symmetry of ideal hydrodynamics, volume-preserving diffeomorphisms, is preserved, we show that linear response formulas are also generally covariant. We discuss our results and argue that in this approach, the applicability of the effective theory is parametrized around a very different quantity than the Knudsen number, offering hope of understanding the applicability of hydrodynamics to small systems.

Blazar-boosted dark matter is a novel mechanism whereby dark matter (DM) particles are accelerated to ultrarelativistic energies through interactions with blazar jets. Focusing on a vector portal DM model, we systematically investigate both elastic and inelastic scattering processes between DM and protons. By analyzing multimessenger data from ground- and space-based observatories, we derive stringent constraints on the DM-proton scattering cross section ${\sigma }_{\chi p}$. Our results improve upon previous limits from the constant cross section and pure elastic scattering scenarios by several orders of magnitude. The distinctive high-energy gamma-ray and neutrino fluxes produced through deep inelastic scattering provide powerful signatures for blazar-boosted dark matter indirect detection, enabling constraints that significantly surpass those from traditional direct detection experiments. Notably, our results suggest that DM could be a new source of high-energy neutrinos from blazars, potentially offering an explanation for IceCube’s observation of TXS $0506+056$.

We investigate current experimental constraints and future search prospects for a hypothetical $SU(2{)}_w$ and $SU(3{)}_c$ singlet spin-zero particle that carries unit electric charge: a singly charged scalar (SCS). In addition to providing useful benchmarks for collider searches, SCS particles are also well-motivated ingredients in relatively minimal dark sectors. We focus on scenarios in which the SCS decays promptly at colliders to a lepton plus either a neutrino or an invisible dark-sector particle of negligible mass. A promptly decaying SCS can easily have appreciable branching ratios to more than one lepton flavor while remaining consistent with constraints on lepton flavor violation. This broadens the allowed range of SCS masses to extend well beyond those for right-handed selectrons, smuons, or staus. For particular benchmark SCS branching ratios, we find that SCS masses above $\sim 185\mathrm{GeV}$ and in a lower-mass window $\sim 80–125\mathrm{GeV}$ are still allowed at 95% confidence level. We carry out Monte Carlo simulations to explore the potential of a boosted-decision-tree-based analysis to probe the surviving SCS parameter space in future searches at the (HL-)LHC, finding a significant increase in sensitivity relative to cut-based analyses both in the lower-mass window and at higher SCS masses.