We calculate contributions to the one-loop renormalization in the spinor sector of the minimal Lorentz-violating extended QED in the second order in Lorentz-breaking parameters. From the renormalizability viewpoint, we show that the inclusion of some of the Lorentz-breaking terms in the model is linked to the presence of others. We also demonstrate that the Ward identities are satisfied up to this order.

We start by considering the production rates of sphalerons with different sizes $\rho$ in the symmetric phase, $T>T_{\mathrm{EW}}$. At small $\rho$, the distribution is cut off by the growing mass $M\sim 1/\rho$, and at large $\rho$ by the magnetic screening mass. In the broken phase, $T<T_{\mathrm{EW}}$, the scale is set by the Higgs vacuum expectation value $v(T)$. We introduce the concept of “sphaleron freeze-out” whereby the sphaleron production rate matches the Hubble Universe expansion rate. At freeze-out the sphalerons are out of equilibrium. Sphaleron explosions generate sound and even gravity waves, when a nonzero Weinberg angle makes them nonspherical. We evaluate the magnitude of $CP$ violation during the sphaleron explosions. We assess its magnitude using the Standard Model Cabbibo-Kobayashi-Maskawa (CKM) quark matrix, first for nonzero and then zero Dirac eigenstates. We find that its magnitude is maximal at the sphaleron freeze-out condition with $T\approx 130\mathrm{GeV}$. We proceed to estimate the amount of $CP$ violation needed to generate the observed magnitude of baryon asymmetry of the Universe, and find that it is about an order of magnitude above our CKM-based estimates. We also relate the baryon asymmetry to the generation of $U(1)$ magnetic chirality, which is expected to be conserved and perhaps visible in polarized intergalactic magnetic fields.

This paper reports the track multiplicity and kinematics of muons, charged pions, and protons from charged-current inclusive ${\overline{\nu }}_{\mu }$ and ${\nu }_{\mu }$ interactions on a water target, measured using a nuclear emulsion detector in the NINJA experiment. A 3-kg water target was exposed to the T2K antineutrino-enhanced beam corresponding to $7.1\times {10}^{20}$ protons on target with a mean energy of 1.3 GeV. Owing to the high granularity of the nuclear emulsion, protons with momenta down to $200\mathrm{MeV}/c$ from the neutrino-water interactions were detected. We find good agreement between the observed data and model predictions for all kinematic distributions other than the number of charged pions and the muon kinematics shapes. These results demonstrate the capability of measurements with nuclear emulsion to improve neutrino interaction models.

The measurements of the muon and electron anomalous magnetic moments hint at physics beyond the standard model. We show why and how models inspired by asymptotic safety can explain deviations from standard model predictions naturally. Our setup features an enlarged scalar sector and Yukawa couplings between leptons and new vectorlike fermions. Using the complete two-loop running of couplings, we observe a well-behaved high-energy limit of models including a stabilization of the Higgs. We find that a manifest breaking of lepton universality beyond standard model Yukawas is not necessary to explain the muon and electron anomalies. We further predict the tau anomalous magnetic moment and new particles in the TeV energy range, whose signatures at colliders are indicated. With small $CP$ phases, the electron EDM can be as large as the present bound.

We study the modular invariance in magnetized torus models. The modular invariant flavor model is a recently proposed hypothesis for solving the flavor puzzle, where the flavor symmetry originates from modular invariance. In this framework, coupling constants such as Yukawa couplings are also transformed under the flavor symmetry. We show that the low-energy effective theory of magnetized torus models is invariant under a specific subgroup of the modular group. Since Yukawa couplings as well as chiral zero modes transform under the modular group, the above modular subgroup (referred to as modular flavor symmetry) provides a new type of modular invariant flavor models with $D_4\times {\mathbb{Z}}_2$, $({\mathbb{Z}}_4\times {\mathbb{Z}}_2)⋊{\mathbb{Z}}_2$, and $({\mathbb{Z}}_8\times {\mathbb{Z}}_2)⋊{\mathbb{Z}}_2$. We also find that conventional discrete flavor symmetries which arise in magnetized torus model are noncommutative with the modular flavor symmetry. Combining both symmetries, we obtain a larger flavor symmetry, which is the semidirect product of the conventional flavor symmetry and the modular flavor symmetry for the nonvanishing Wilson line. For the vanishing Wilson line, we have additional ${\mathbb{Z}}_2$ symmetry, i.e., parity, which is the unique common element between the conventional flavor symmetry and the modular flavor symmetry.

Strong gravitational lensing can produce multiple images of the same gravitational-wave signal, each arriving at different times and with different magnification. Previous work has explored if lensed pairs exist among the known high-significance events from the LIGO and Virgo Collaboration’s GWTC-1 catalog and found no evidence of this. However, the possibility remains that weaker counterparts of these events are present in the data, unrecovered by previous searches. We conduct a targeted search specifically looking for subthreshold lensed images of known binary black hole (BBH) observations from GWTC-1. We recover candidates matching three of the additional events first reported by Venumadhav et al. [Phys. Rev. D 101, 083030 (2020)] but find no evidence for additional BBH events. We also find no evidence that any of the Venumadhav et al. observations are lensed counterparts. We demonstrate how this type of counterpart search can constrain hypotheses about the overall source and lens populations and we rule out at very high confidence the extreme hypothesis that all heavy BBH detections are in fact lensed systems at high redshift with intrinsic masses $<15M_{\odot }$.

Using perturbative expansion in terms of powers of the rotation parameter $a$ we construct the axisymmetric and asymptotically flat black-hole metric in the $D$-dimensional Einstein-Gauss-Bonnet theory. In five-dimensional spacetime we find two solutions to the field equations, describing the asymptotically flat black holes, though only one of them is perturbative in mass, that is, goes over into the Minkowski spacetime when the black-hole mass goes to zero. We obtain the perturbative black-hole solution up to the order $\mathcal{O}(\alpha a^3)$ for any $D$, where $\alpha$ is the Gauss-Bonnet coupling, while the $D=5$ solution which is nonperturbative in mass is found in analytic form up to the order $\mathcal{O}(\alpha a^7)$. In order to check the convergence of the expansion in $a$ we analyze characteristics of photon orbits in this spacetime and compute frequencies of the photon orbits and radius of the photon sphere.

Scalars that carry lepton number can help mediate would-be lepton number–violating processes, such as neutrinoless double $\beta$ decay or lepton scattering–mediated nucleon-antinucleon conversion. Here, we show that such new scalars can also solve the anomaly in precision determinations of the fine-structure constant $\alpha$ from atom interferometry and from the electron’s anomalous magnetic moment, $a_e\equiv (g-2{)}_e/2$, by reducing $|a_e|$. Study of the phenomenological constraints on these solutions favor a doubly charged scalar with mass below the GeV scale. Significant constraints arise from the measurement of the parity-violating asymmetry in Møller scattering, and we consider the implications of the next-generation MOLLER experiment at Jefferson Laboratory and of an improved $a_e$ measurement.

We perform a multivariate analysis of Higgs-pair production via the decay channel $HH\to b\overline{b}\gamma \gamma$ at the future 100 TeV $pp$ collider to determine the trilinear Higgs self–coupling (THSC) ${\lambda }_{3H}$, which takes the value of 1 in the standard model. We consider all known background processes. For the signal we adopt the most recent event generator of POWHEG-BOX-V2 to exploit the NLO distributions for toolkit for multivariate data analysis (TMVA). Through the technique of boosted decision tree (BDT) analysis trained for ${\lambda }_{3H}=1$, compared to the conventional cut-and-count approach, the signal-to-background ratio improves tremendously from about $1/10$ to 1 and the significance can reach up to 20.5 with a luminosity of $3{\mathrm{ab}}^{-1}$ without including systematic uncertainties. In addition, by implementing a likelihood fitting of the signal-plus-background $M_{\gamma \gamma bb}$ distribution with optimized bin sizes, it is possible to determine the THSC with the precision of 7.5% at 68% CL even at the early stage of 100 TeV hadron collider with $3{\mathrm{ab}}^{-1}$.

Gravitational physics is arguably better understood in the presence of a negative cosmological constant than a positive one, yet there exist strong technical similarities between the two settings. These similarities can be exploited to enhance our understanding of the more speculative realm of quantum cosmology, building on robust results regarding anti–de Sitter black holes describing the thermodynamics of holographic quantum field theories. To this end, we study four-dimensional gravitational path integrals in the presence of a negative cosmological constant and with minisuperspace metrics. We put a special emphasis on boundary conditions and integration contours. The Hawking-Page transition is recovered, and we find that below the minimum temperature required for the existence of black holes the corresponding saddle points become complex. When the asymptotic anti–de Sitter space is cut off at a finite distance, additional saddle points contribute to the partition function, albeit in a very suppressed manner. These findings have direct consequences for the no-boundary proposal in cosmology, because the anti–de Sitter calculation can be brought into one-to-one correspondence with a path integral for de Sitter space with Neumann conditions imposed at the nucleation of the Universe. Our results lend support to recent implementations of the no-boundary proposal focusing on momentum conditions at the “big bang.”

We relax the assumption of time translation and Lorentz boost symmetry in theories involving massless spin-2 gravitons, while maintaining a basic notion of locality that there is no instantaneous signaling at a distance. We project out longitudinal modes, leaving only 2 degrees of freedom of the graviton. Our previous work, which assumed time translation symmetry, found that the Lorentz boost symmetry is required to ensure locality at leading order. In this work, without assuming time translations or Lorentz boosts, we show that locality of the exchange action between matter sources demands that massless spin-2, at leading order, organizes into Einstein-Hilbert plus a Gauss-Bonnet term with a prefactor that is constrained to be a particular function of time; while in the matter sector we recover time translation and Lorentz boost symmetry. Finally, we comment on whether the time dependence of the Gauss-Bonnet prefactor may be forbidden by going to higher order in the analysis and we mention that other possibilities are anticipated if graviton mass terms are included.

The Unruh effect states that a uniformly linearly accelerated observer with proper acceleration $a$ experiences Minkowski vacuum as a thermal state in the temperature $T_{\mathrm{lin}}=a/(2\pi )$, operationally measurable via the detailed balance condition between excitation and deexcitation probabilities. An observer in uniform circular motion experiences a similar Unruh-type temperature $T_{\text{circ}}$, operationally measurable via the detailed balance condition, but $T_{\text{circ}}$ depends not just on the proper acceleration but also on the orbital radius and on the excitation energy. We establish analytic results for $T_{\text{circ}}$ for a massless scalar field in $3+1$ and $2+1$ spacetime dimensions in several asymptotic regions of the parameter space, and we give numerical results in the interpolating regions. In the ultrarelativistic limit, we verify that in $3+1$ dimensions $T_{\text{circ}}$ is of the order of $T_{\mathrm{lin}}$ uniformly in the energy, as previously found by Unruh, but in $2+1$ dimensions, $T_{\text{circ}}$ is significantly lower at low energies. We translate these results to an analogue spacetime nonrelativistic field theory in which the circular acceleration effects may become experimentally testable in the near future. We establish in particular that the circular motion analogue Unruh temperature grows arbitrarily large in the near-sonic limit, encouragingly for the experimental prospects, but the growth is weaker in effective spacetime dimension $2+1$ than in $3+1$.

We holographically investigate the scalarization in the Einstein-scalar-Gauss-Bonnet gravity with a negative cosmological constant. We find that instability exists for both Schwarzschild-AdS (anti–de Sitter) and Reissner-Nordström-AdS black holes with planar horizons when we have proper interactions between the scalar field and the Gauss-Bonnet curvature corrections. We relate such instability to possible holographic scalarization and construct the corresponding hairy black hole solutions in the presence of the cosmological constant. Employing the holographic principle, we expect that such bulk scalarization corresponds to the boundary description of the scalar hair condensation without breaking any symmetry, and we calculate the related holographic entanglement entropy of the system. Moreover, we compare the mechanisms of the holographic scalarizations caused by the effect of the coupling of the scalar field to the Gauss-Bonnet term and holographic superconductor effect in the presence of an electromagnetic field, and unveil their differences in the effective mass of the scalar field, the temperature-dependent property, and the optical conductivity.

A new exact solution to the field equations in the Einstein-Gauss-Bonnet modified theory of gravity, for a six-dimensional spherically symmetric static distribution of a perfect fluid source is presented. The pressure isotropy equation is integrated after a form for the temporal potential proportional to the radius is postulated to close the system of equations. For a specific choice of the coupling parameter it is demonstrated that the matching of the interior and exterior spacetimes is explicitly achievable. The general model has been tested to be physically acceptable in this framework using criteria extrapolated from the standard four dimensional theory and after locating a suitable parameter space through fine-tuning. A vanishing pressure hypersurface signifying a boundary exists and the speed of sound is subluminal throughout the interior of the matter distribution. Furthermore, all energy conditions are satisfied. Finally, the Chandrasekhar adiabatic stability bound is satisfied.

In this work, the study of traversable wormholes in $f(R)$ massive gravity with the function $f(R)=R+{\alpha }_1{R}^n$, where ${\alpha }_1$ and $n$ are arbitrary constants, is considered. We choose the shape function of the form $b(r)=r\exp (-\alpha (r-r_0))$ with $\alpha$ and $r_0$ being an arbitrary constant and a radius of the wormhole throat, respectively. Here $\alpha$ affects the radius of curvature of the wormhole. We consider a spherically symmetric and static wormhole metric and derive field equations. Moreover, we visualize the wormhole geometry using embedding diagrams. Furthermore, we check the null, weak, dominant, and strong energy conditions at the wormhole throat with a radius $r_0$ invoking three types of redshift functions, $\mathrm{\Phi }=\text{constant}$, ${\gamma }_1/r$, $\log (1+{\gamma }_2/r)$ with ${\gamma }_1$ and ${\gamma }_2$ are arbitrary real constants. We also compute the volume integral quantifier to calculate the amount of the exotic matter near the constructed wormhole throat.

The distinctive effects of fuzzy dark matter are most visible at nonlinear galactic scales. We present the first simulations of mixed fuzzy and cold dark matter, obtained with an extended version of the nyx code. Fuzzy (or ultralight or axionlike) dark matter dynamics are governed by the comoving Schrödinger-Poisson equation. This is evolved with a pseudospectral algorithm on the root grid, and with finite differencing at up to six levels of adaptive refinement. Cold dark matter is evolved with the existing $N$-body implementation in nyx. We present the first investigations of spherical collapse in mixed dark matter models, focusing on radial density profiles, velocity spectra, and soliton formation in collapsed halos. We find that the effective granule masses decrease in proportion to the fraction of fuzzy dark matter which quadratically suppresses soliton growth, and that a central soliton forms only if the fuzzy dark matter fraction is greater than 10%. The nyx framework supports baryonic physics and key astrophysical processes such as star formation. Consequently, axionyx will enable increasingly realistic studies of fuzzy dark matter astrophysics.

We present the new recombination code hyrec-2, which achieves the same accuracy as the state-of-the-art codes hyrec and cosmorec and, at the same time, surpasses the computational speed of the code recfast commonly used for cosmic microwave background (CMB) anisotropy data analyses. hyrec-2 is based on an effective four-level atom model, accounting exactly for the nonequilibrium of highly excited states of hydrogen, and very accurately for radiative transfer effects with a correction to the Lyman-$\alpha$ escape rate. The latter is computed with the original hyrec and tabulated as a function of temperature, along with its derivatives with respect to the relevant cosmological parameters. This enables the code to keep the same accuracy as the original hyrec over the full 99.7% confidence region of cosmological parameters currently allowed by Planck, while running in under one millisecond on a standard laptop. Our code leads to no noticeable bias in any cosmological parameters even in the case of an ideal cosmic-variance-limited experiment up to $\ell =5000$. Beyond CMB anisotropy calculations, hyrec-2 will be a useful tool to compute various observables that depend on the recombination and thermal history, such as the recombination spectrum or the 21-cm signal.

We studied the formation of Y junctions for transonic elastic strings. In particular, using the general solution for these strings, which is described by left- and right-moving modes, we obtained the dynamics of kinks and Y junctions. Considering the linearized ansatz for straight strings, we constructed the parameter region space for which the formation of Y junctions due to strings collisions is allowed.

We consider the effects of active-sterile secret neutrino interactions, mediated by a new pseudoscalar particle, on high and ultrahigh energy neutrino fluxes. In particular, we focus on the case of three active and one sterile neutrino coupled by a flavor dependent interaction, extending the case of one active and one sterile neutrino we have recently examined. We find that, depending on the kind of interaction of a sterile neutrino with the active sector, new regions of the parameter space for secret interactions are now allowed, with the masses of a sterile neutrino and scalar mediator ranging from 10 MeV to 1 GeV, leading to interesting phenomenological implications on two benchmark fluxes we consider, namely an astrophysical power law flux, in the range below 100 PeV, and a cosmogenic flux, in the ultrahigh energy range. First of all, the final active fluxes can present a measurable depletion observable in future experiments. Especially, in the case of only a ${\nu }_{\tau }-{\nu }_s$ interaction, we find that the effects on the astrophysical power law flux can be so large to be already probed by the IceCube experiment. Moreover, we find intriguing features in the energy dependence of the flavor ratio.

We propose a new mechanism for the formation of dark matter clumps in the radiation era. We assume that a light scalar field is decoupled from matter and oscillates harmonically around its vacuum expectation value. We include self-interactions and consider the nonrelativistic regime. The scalar dynamics are described by a fluid approach where the fluid pressure depends on both quantum and self-interaction effects. When the squared speed of sound of the scalar fluid becomes negative, an instability arises and the fluctuations of the scalar energy-density field start growing. They eventually become nonlinear and clumps form. Subsequently, the clumps aggregate and reach a universal regime. Afterwards, they play the role of cold dark matter. We apply this mechanism first to a model with a negative quartic term stabilized by a positive self-interaction of order six, and then to axion monodromy, where a subdominant cosine potential corrects a mass term. In the first case, the squared speed of sound becomes negative when the quartic term dominates, leading to a tachyonic instability. For axion monodromy, the instability starts very slowly after the squared speed of sound first becomes negative and then oscillates around zero. Initially the density perturbations perform acoustic oscillations due to the quantum pressure. Eventually, they start growing exponentially due to a parametric resonance. The shape and the scaling laws of the clumps depend on their formation mechanism. When the tachyonic phase takes place, the core density of the clumps is uniquely determined by the energy density at the beginning of the instability. On the other hand, for axion monodromy, the core density scales with the soliton mass and radius. This difference comes from the crucial role that the quantum pressure plays in both the parametric resonance in the linear regime and in the nonlinear formation regime of static scalar solitons. In both scenarios, the scalar-field clumps span a wide range of scales and masses, running from the size of atoms to that of galactic molecular clouds, and from ${10}^{-3}\mathrm{gram}$ to thousands of solar masses. Because of finite-size effects, both from the source and the lens, these dark matter clumps are far beyond the reach of microlensing observations. We find that the formation redshift of the scalar clumps can span a large range in the radiation era; the associated background temperature can vary from 10 eV to ${10}^5\mathrm{GeV}$, and the scalar-field mass from ${10}^{-26}\mathrm{GeV}$ to 10 GeV.