The details of the minimal cosmological standard model (MCSM) proposed in [The minimal cosmological standard model, arXiv:2403.05390.] are discussed. The model is based on the scale-symmetry and the global Peccei-Quinn (PQ) symmetry with a key assumption that the latter is broken only in the gravity sector in a scale-invariant manner. We show that the model provides a quite simple unified framework for the unknown history of the Universe from inflation to the epoch of big-bang nucleosynthesis, simultaneously addressing key puzzles of high energy theory and cosmology: (i) the origin of scales, (ii) primordial inflation, (iii) matter-antimatter asymmetry, (iv) tiny neutrino masses, (v) dark matter, and (vi) the strong $CP$-problem. Scale symmetry can be exact, and the Planck scale is dynamically generated. The presence of Gauss-Bonnet term may safely retain dangerous nonperturbative symmetry-breaking effects negligible, allowing a large-field trans-Planckian inflation along the PQ-field. Isocurvature perturbations of axi-Majorons are suppressed. A sizable amount of PQ-number asymmetry is generated at the end of inflation, and conserved afterward. Domain wall problem is absent due to the nonrestoration of the symmetry and the nonzero PQ-number asymmetry. Baryogenesis can be realized by either the transfer of the PQ-number asymmetry through the seesaw sector, or by resonant leptogenesis. Dark matter is purely cold axi-Majorons from the misalignment contribution with the symmetry-breaking scale of $\mathcal{O}({10}^{12})\mathrm{GeV}$. Hot axi-Majorons from the decay of the inflaton become a natural source for a sizable amount of dark radiation. Inflationary gravitational waves have information about the mass parameters of the lightest left-handed and right-handed neutrinos, thanks to the presence of an early matter-domination era driven by the long-lived lightest right-handed neutrino species.

We revisit the role of primordial black holes (PBHs) as potential dark matter (DM) candidates, particularly focusing on light asteroid-mass PBHs. These PBHs are expected to emit particles through Hawking evaporation that can generate cosmic rays (CRs), eventually producing other secondary radiations through their propagation in the Milky Way, in addition to prompt emissions. Here, we perform a comprehensive analysis of CR signals resulting from PBH evaporation, incorporating the full CR transport to account for reacceleration and diffusion effects within the Milky Way. In particular, we revisit the $e^{\pm }$ flux produced by PBHs, using Voyager 1, and study for the first time the diffuse x-ray emission from the up-scattering of Galactic ambient photons due to PBH-produced $e^{\pm }$ via the inverse Compton effect using Xmm-Newton data, as well as the morphological information of the diffuse 511 keV line measured by Integral/Spi. In doing so, we provide leading constraints on the fraction of DM that can be in form of PBHs in a conservative way, while also testing how different assumptions on spin and mass distributions affect our conclusions.

Deconvolving (“unfolding”) detector distortions is a critical step in the comparison of cross-section measurements with theoretical predictions in particle and nuclear physics. However, most existing approaches require histogram binning while many theoretical predictions are at the level of statistical moments. We develop a new approach to directly unfold distribution moments as a function of another observable without having to first discretize the data. Our moment unfolding technique uses machine learning and is inspired by Boltzmann weight factors and generative adversarial networks (GANs). We demonstrate the performance of this approach using jet substructure measurements in collider physics. With this illustrative example, we find that our moment unfolding protocol is more precise than bin-based approaches and is as or more precise than completely unbinned methods.

In this work, we present a unified theoretical framework that simultaneously addresses some of the most intriguing puzzles in particle physics and cosmology, namely the origins of neutrino mass, baryon asymmetry, and cosmic inflation. In our model, inflation is driven by a combination of the Standard Model Higgs, the type II seesaw Higgs responsible for neutrino mass generation, and the unified symmetry-breaking Higgs field. During inflation, nonzero values of the latter field ensure the absence of the monopole problem. The baryon asymmetry is generated through the Affleck-Dine mechanism, facilitated by the nonzero angular motion in the phase of a complex scalar field, which is part of the inflaton. We find that the successful parameter region for generating baryon asymmetry through a renormalizable term in the scalar potential requires a rather heavy type II seesaw triplet, with a mass well beyond the TeV scale. Inflationary observables, in particular, the spectral index is in excellent agree with experimental observation, whereas tensor-to scalar ratio is expected to be probed by the future LiteBIRD and CMB-S4 missions.

The theory of radiation of photons from Dirac particles caused by a projective measurement is developed. The explicit expressions for the inclusive probability to record a chain of events that the Dirac fermion had been measured in a certain state and after that the photon was recorded are derived. Stimulated and spontaneous radiations are considered. It is shown that in both cases, the properties of radiation due to measurement resembles the properties of edge or transition radiation. In the case of stimulated radiation from a single particle, its wave function creates photons coherently as a charged fluid, i.e., the amplitudes of radiation from the points of the particle wave packet are summed. In the case of spontaneous radiation, the radiation of photons is incoherent, i.e., the probabilities of radiation from the points of the particle wave packet are added up. It is shown that stimulated radiation due to measurement can be used to trace the dynamics and collapse of the wave function of the Dirac particle. A systematic procedure taking into account a finiteness of the measurement time is presented. It is established that radiation due to measurement can be used as a source of hard photons, but the finiteness of the measurement time imposes an upper bound on the energy of radiated photons: the measurement time must be smaller than the radiation formation time, the latter being in inverse proportion to the photon energy. In the ultrarelativistic limit, the radiation formation time can be rather large. Several examples of radiation due to measurement of the state of free Dirac particles are investigated in detail. Namely, we scrutinize the radiation due to measurement of the spin projection, of the momentum, and of the coordinate for a general initial state of Dirac particles. The particular cases of uncorrelated and entangled particles in the beam are considered.

The homogeneous precession domain (HPD) of superfluid ${}^3\mathrm{He}$ has recently been identified as a detection medium which might provide sensitivity to the axion-nucleon coupling $g_{aNN}$ competitive with, or surpassing, existing experimental proposals. In this work, we make a detailed study of the statistical and dynamical properties of the HPD system in order to make realistic projections for a full-fledged experimental program. We include the effects of clock error and measurement error in a concrete readout scheme using superconducting qubits and quantum metrology. This work also provides a more general framework to describe the statistics associated with the axion gradient coupling through the treatment of a transient resonance with a nonstationary background in a time-series analysis. Incorporating an optimal data-taking and analysis strategy, we project a sensitivity approaching $g_{aNN}\sim {10}^{-12}{\mathrm{GeV}}^{-1}$ across a decade in axion mass.

We present a solution to the electroweak hierarchy problem, where the relevant new particles are third-generation philic and hidden in Standard Model processes with third-generation fermions. Due to this feature, the mass bounds from direct searches are much weaker, and the required fine-tuning can be reduced drastically. A concrete model is constructed based on a $SU(6)/Sp(6)$ fundamental composite Higgs model with collective symmetry breaking and an extended hypercolor mechanism. The construction allows us to raise the scale $f$ to $\sim 3\mathrm{TeV}$, corresponding to resonances at $M_{\rho }\gtrsim 10\mathrm{TeV}$, without much tuning—employing ingredients that are naturally inherent in the (composite) Goldstone-Higgs framework. The experimental signatures are discussed in detail. It is found that current bounds allow for a model with negligible tuning.

We revisit the stability of the Standard Model vacuum and investigate its quantum effective potential using the highest available orders in perturbation theory and the most accurate determination of input parameters to date. We observe that the stability of the electroweak vacuum centrally depends on the values of the top mass and the strong coupling constant. We estimate that reducing their uncertainties by a factor of 2–3 is sufficient to establish or refute Standard Model vacuum stability at the $5\sigma$ level. We further investigate vacuum stability for a variety of singlet scalar field extensions with and without flavor using the Higgs portal mechanism. We identify the beyond Standard Model parameter spaces for stability and find sizable room for new physics. We further study the phenomenology of Planck-safe models at colliders and determine the impact on the Higgs trilinear, the Higgs-to-electroweak-boson, and the Higgs quartic couplings, some of which can be significant. The former two can be probed at the HL-LHC; the latter requires a future collider with sufficient energy and precision such as the FCC-hh.

Using $(10087\pm 44)\times {10}^{6}J/\psi$ events collected with the BESIII detector, we search for the rare decay $J/\psi \to \gamma D^0+\mathrm{c}.\mathrm{c}.$ for the first time. No significant signal is observed and the upper limit on the branching fraction is determined to be $\mathcal{B}(J/\psi \to \gamma D^0+\mathrm{c}.\mathrm{c}.)<9.1\times {10}^{-8}$ at 90% confidence level.

One version of the principle of equivalence, as originally formulated by Einstein, states that “gravity” can be mimicked locally by going to an “accelerated frame of reference.” As highlighted by Synge, the physical content of this principle remains obscure in so far as it does not refer to the Riemann tensor $R_{abcd}$, which encodes the true effects of gravity. We here give the acceleration profile of a Born rigid, Rindler esque, frame that can mimic a gravitational field corresponding to a given $R_{abcd}$. The generalized deviation equation that yields this result also has centrifugal and Coriolis terms appearing in a purely relational context, yielding a similar connection between angular velocity of rotating, rigid inertial frames and Riemann. We comment briefly on implications for the Mach principle.

Using $(27.12\pm 0.14)\times {10}^8$ $\psi (3686)$ decays and data samples of $e^{+}{e}^{-}$ collisions with $\sqrt{s}$ from 4.130 to 4.780 GeV collected with the BESIII detector, we report the first observation of the electromagnetic Dalitz transition $h_c\to e^{+}{e}^{-}{\eta }_c$ with a statistical significance of $5.4\sigma$. We measure the ratio of the branching fractions $\frac{\mathcal{B}(h_c\to e^{+}{e}^{-}{\eta }_c)}{\mathcal{B}(h_c\to \gamma {\eta }_c)}$ separately for the $h_c$ samples produced via $\psi (3686)\to {\pi }^0{h}_c$ and $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{h}_c$. The average ratio is determined to be $(0.59\pm 0.10(\mathrm{stat})\pm 0.04(\mathrm{syst}))\%$, where the uncertainty includes both statistical and systematic components.

We study the modular symmetry of localized modes on fixed points of $T^2/{\mathbb{Z}}_2$ orbifold. First, we find that the localized modes with even (odd) modular weight generally have $\mathrm{\Delta }(6n^2)$ [${\mathrm{\Delta }}^{\prime }(6n^2)$] modular flavor symmetry. Moreover, when we consider an additional Ansatz, the localized modes with even (odd) modular weight generally enjoy $S_3$ ($S_4^{\prime }$) modular flavor symmetry, and we show the concrete wave functions of the localized modes.

We study figures of equilibrium of barotropic fluid with uniform, nonvanishing, values of specific angular momentum in the gravitational field of the Reissner-Nordström (RN) space-time. The RN metric describes the space-time of a charged, static, spherically symmetric source of gravity, which happens to be a naked singularity when the absolute value of charge, $Q$, exceeds the mass, $M$. We treat the general relativistic RN solution as a representative of a wider class of spherically symmetric space-times in various theories of gravity that admit a (“zero-gravity”) spherical surface on which a test particle can remain at rest. The mechanism through which an orbiting fluid could lose its angular momentum in the vicinity of this zero-gravity sphere is as yet unknown; the fluid may possibly not come to rest there. In the gravity of the RN naked singularity, all equipotential surfaces of bound fluid with nonvanishing angular momentum have the topology of a torus (or two), and each of them may be filled by fluid in hydrostatic equilibrium. Depending on the value of the angular momentum of the fluid, the tori are completely or partly outside the zero-gravity sphere, and the locus of maximum pressure is always outside that sphere. The equipotential surfaces of unbound fluid have the topology of cylinders extending to infinity that are conducive to jetlike outflows of the fluid. Unlike in the black hole case, rotating fluid in the RN naked singularity metric can never accrete onto the central source of gravity; if bound, it will orbit the singularity inside one of the tori, and if unbound, it will flow out to infinity. Some of the tori shapes may correspond to the images reconstructed from the Einstein Horizon Telescope observations of Sgr A* and M87.

In a binary merger with a small mass ratio, as the secondary body approaches the innermost stable circular orbit (ISCO) of the primary black hole, the motion transitions from the adiabatic inspiral to the plunge governed by the geodesic equation. The plunge orbit is expected to excite the ringdown gravitational wave, which encodes information about the primary black hole’s geometry. The details of the transition regime depend on the binary’s mass ratio through radiation fluxes, which in turn influence the initial conditions for the plunge. As such, the mass ratio affects the post-ISCO ringdown gravitational wave excitation. In this study, we numerically investigate the mass ratio dependence of higher harmonic quasi-normal mode excitations in the post-ISCO gravitational waves of rapidly spinning black holes, based on the Teukolsky-Sasaki-Nakamura formalism. We consider the effect of mass ratio on the gravitational waves by accounting for the energy and angular momentum losses during the transition regime following the Ori-Thorne procedure. We examine two mass ratio scenarios: the intermediate mass ratio (IMR) and the extreme mass ratio (EMR). Our main finding is that higher harmonic quasinormal modes are significantly excited in an IMR merger involving a highly spinning primary black hole. This implies that detecting an IMR merger involving such a primary black hole with space-based gravitational wave interferometers can provide valuable opportunities to infer black hole properties or test general relativity with excellent precision.

We numerically investigate the imprints of gravitational radiation-reaction driven changes to a black hole’s mass and spin on the corresponding ringdown waveform. We do so by comparing the dynamics of a perturbed black hole evolved with the full (nonlinear) versus linearized Einstein equations. As expected, we find that the quasinormal mode amplitudes extracted from nonlinear evolution deviate from their linear counterparts at third order in initial perturbation amplitude. For perturbations leading to a change in the black hole mass and spin of $\sim 5\%$, which is reasonable for a remnant formed in an astrophysical merger, we find that nonlinear distortions to the complex amplitudes of some quasinormal modes can be as large as $\sim 50\%$ at the peak of the waveform. Furthermore, the change in the mass and spin results in a drift in the quasinormal mode frequencies, which for large amplitude perturbations causes the nonlinear waveform to rapidly dephase with respect to its linear counterpart. Surprisingly, despite these nonlinear effects creating significant deviations in the nonlinear waveform, we show that a linear quasinormal mode model still performs quite well from close to the peak amplitude onward. Comparing the quality of quasinormal mode fits for the linear and nonlinear waveforms, we show that the main obstruction to measuring high-$n$ overtones is the transient part of the waveform, already present at the linear level.

Subjected to the tidal field of its companion, each component of a coalescing binary suffers a slow change in its mass (tidal heating) and spin (tidal torquing) during the inspiral and merger. For black holes, these changes are associated with their absorption of energy and angular momentum fluxes. This effect modifies the inspiral rate of the binary, and consequently, the phase and amplitude of its gravitational waveform. Numerical relativity (NR) waveforms contain these effects inherently, whereas analytical approximants for the early inspiral phase have to include them manually in the energy balance equation. In this work, we construct IMRPhenomD_Horizon, a frequency-domain gravitational waveform model that incorporates the effects of tidal heating of black holes. This is achieved by recalibrating the inspiral phase of the waveform model IMRPhenomD to incorporate the phase corrections for tidal heating. We also include corrections to the amplitude, but add them directly to the inspiral amplitude model of IMRPhenomD. First we demonstrate that the inclusion of the corrections, especially in the phase, confers an overall improvement in the phase agreement between the analytical inspiral model (uncalibrated SEOBNRv2) and NR data. The model presented here is faithful, with less than 1% mismatches against a set of hybrid waveforms (except for one outlier that barely breaches this limit). The recalibrated model shows mismatches of up to $\sim 14\%$ with IMRPhenomD for high mass ratios and spins. Amplitude corrections become less significant for higher mass ratios, whereas the phase corrections leave more impact—suggesting that the former is practically irrelevant for gravitational wave data analysis in Advanced LIGO (aLIGO), Virgo and KAGRA. Comparing with a set of 219 numerical relativity waveforms, we find that the median of mismatches decreases by $\sim 4\%$ in aLIGO zero-detuned high power noise curve, and by $\sim 1.5\%$ with a flat noise curve. This implies a modest but notable improvement in waveform accuracy.

Since the relic gravitons are produced in entangled states of opposite (comoving) three-momenta, their distributions and their averaged multiplicities must determine the maximal frequency of the spectrum above which the created pairs are exponentially suppressed. The absolute upper bound on the maximal frequency derived in this manner coincides with the THz domain and does not rely on the details of the cosmological scenario. The THz limit also translates into a constraint of the order of ${10}^{-33}$ on the minimal chirp amplitudes that should be effectively reached by all classes of hypothetical detectors aiming at the direct scrutiny of a signal in the frequency domain that encompasses the MHz and the GHz bands. The obtained high-frequency limit is deeply rooted in the quantumness of the produced gravitons whose multiparticle final sates are macroscopic but always nonclassical. Since the unitary evolution preserves their coherence, the quantumness of the gravitons can be associated with an entanglement entropy that is related with the loss of the complete information on the underlying quantum field. It turns out that the reduction of the density matrix in different bases leads to the same von Neumann entropy whose integral over all the modes of the spectrum is dominated by the maximal frequency. Thanks to the THz bound the total integrated entropy of the gravitons can be comparable with the cosmic microwave background entropy but not larger. Besides the well-known cosmological implications, we then suggest that a potential detection of gravitons between the MHz and the THz may therefore represent direct evidence of macroscopic quantum states associated with the gravitational field.

In this work, we have studied the medium effects in strange quark matter in the framework of a grand-canonical ensemble using the phenomenological quasiparticle model. This model is studied with proper self-consistent thermodynamical treatment by incorporating chemical-potential-dependent quark mass. We have also included the vector interaction in a self-consistent way. The main aim of this work is to explore the proper thermodynamic treatment in addressing the medium effects at both zero and finite temperatures. In the case of the finite temperature, we explore the study of self-consistent thermodynamics in the isothermal as well as the isentropic processes. The effect of finite temperature and lepton fraction have been studied on the equation of state, speed of sound, and particle fraction. The $M\text{−}R$ and $M\text{−}\mathrm{\Lambda }$ diagrams are found to be consistent with the observational constraints.

In this paper, we investigate the impact of transient noise artifacts, or “glitches,” on gravitational-wave inference from ground-based interferometer data and test how modeling and subtracting these glitches affects the inferred parameters. Because of their time-frequency morphology, broadband glitches cause moderate to significant biasing of posterior distributions away from true values. In contrast, narrow band glitches induce negligible biasing effects, due to distinct signal and glitch morphologies. We inject simulated binary black hole signals into data containing three occurring glitch types from past LIGO-Virgo observing runs and reconstruct both signal and glitch waveforms using bayeswave, a wavelet-based Bayesian analysis. We apply the standard LIGO-Virgo-KAGRA deglitching procedure to the detector data, which consists of subtracting from calibrated LIGO data the glitch waveform estimated by the joint bayeswave inference. We produce posterior distributions on the parameters of the injected signal before and after subtracting the glitch, and we show that removing the transient noise effectively mitigates bias from broadband glitches. This study provides a baseline validation of existing techniques, while demonstrating waveform reconstruction improvements to the Bayesian algorithm for robust astrophysical characterization in glitch-prone detector data.

An exact solution of the Dirac equation in the presence of an arbitrary electromagnetic plane wave is found, which corresponds to a focused electron wave packet, with the focus of the wave packet moving at the speed of light in the opposite direction of the average momentum of the electron wave packet (unless the plane wave is so intense to reflect the electron). The photon spectrum emitted by such an electron wave packet in the presence of a linearly polarized plane wave is studied both analytically and numerically. The spectrum is also compared with the one emitted by a single-momentum, plane-wave electron in the case of the electron being initially counterpropagating (on average for the flying-focus case) with the plane wave and within the locally constant field approximation. It is found that if the electron flying-focus wave packet is focused beyond a Compton wavelength, the angular distribution of the emitted radiation along the magnetic field of the electromagnetic plane wave is broader than for an electron with definite momentum. Corresponding the maximum value of the photon yield on the transverse plane is smaller in the flying-focus electron case. This could represent an experimental signature of a laser-driven flying-focus electron wave packet.