In this paper, we investigate the double covering of the modular ${\mathrm{\Gamma }}_5\simeq A_5$ group and derive all the modular forms of weight one for the first time. The modular forms of higher weights are also explicitly given by decomposing the direct products of weight-one forms. For the double-covering group ${\mathrm{\Gamma }}_5^{\prime }\simeq A_5^{\prime }$, there exist two inequivalent two-dimensional irreducible representations, into which we can assign two right-handed neutrino singlets in the minimal seesaw model. Two concrete models with such a salient feature have been constructed to successfully explain lepton mass spectra and flavor mixing pattern. The allowed parameter space for these two minimal scenarios has been numerically explored and analytically studied with some reasonable assumptions.

We revisit the possibility of light-scalar dark matter, in the MeV to GeV mass bracket and coupled to electrons through fermion or vector mediators, in light of significant experimental and observational advances that probe new physics below the GeV scale. We establish new limits from electron colliders and fixed-target beams and derive the strength of loop-induced processes that are probed by precision physics, among other laboratory probes. In addition, we compute the cooling bound from SN1987A, consider self-scattering, structure formation, and cosmological constraints as well as the limits from dark matter–electron scattering in direct detection experiments. We then show that the combination of constraints largely excludes the possibility that the galactic annihilation of these particles may explain the long-standing International Gamma-Ray Astrophysics Laboratory excess of 511 keV photons as observed in the Galactic bulge. As a caveat to these conclusions, we identify the resonant annihilation regime where the vector mediator goes nearly on shell.

Lattice tensor representations are explored to investigate the lattice Landau gauge gluon propagator for the pure SU(3) Yang-Mills gauge theory in four dimensions. The analysis of several tensor bases allows to quantify the completeness of the tensor bases considered and the deviations of the lattice results from the continuum theory, and to estimate the theoretical uncertainty in the propagator. Furthermore, our analysis tests continuum-based relations with the lattice data and shows that the lattice Landau gauge gluon propagator is described by a unique form factor, as in the continuum formulation.

We apply recent developments in large momentum effective theory (LaMET) to formulate a nonperturbative calculation of the single transverse-spin asymmetry from the so-called Sivers mechanism in terms of quasi-transverse-momentum-dependent quark distribution functions. When the spin asymmetry is defined as the ratio of the quark Sivers function over the spin-averaged distribution, it can be directly calculated in terms of the relevant quasidistributions with the soft functions and perturbative matching kernels canceling out. Apart from the general formula presented, we have verified the result in the small transverse distance limit at one-loop order, which reduces to a collinear expansion at the twist-three level.

In this paper, we holographically quantify the entanglement and complexity for mixed states by following the prescription of purification. The bulk theory we consider in this work is a hyperscaling violating solution, characterized by two parameters, hyperscaling violating exponent $\theta$ and dynamical exponent $z$. This geometry is due to a nonrelativistic strongly coupled theory with hidden Fermi surfaces. We first compute the holographic analogy of entanglement of purification, denoted as the minimal area of the entanglement wedge cross section and observe the effects of $z$ and $\theta$. Then in order to probe the mixed state complexity we compute the mutual complexity for the Banados Teitelboim Zanelli (BTZ) black hole and the hyperscaling violating geometry by incorporating the holographic subregion complexity conjecture. We carry this out for two disjoint subsystems separated by a distance and also when the subsystems are adjacent with subsystems making up the full system. Furthermore, various aspects of holographic entanglement entropy such as the entanglement Smarr relation, the Fisher information metric, and the butterfly velocity have also been discussed.

We report a new one-parameter family of spherically symmetric, inhomogeneous, and time-dependent solutions of the vacuum Brans-Dicke field equations which are conformal to the Roberts scalar field geometries of Einstein gravity. The new solution is spherical and time-dependent and contains a naked central singularity. We use it as a seed to generate another two-parameter family of solutions using a known symmetry of vacuum Brans-Dicke gravity.

The scientific impact of current and upcoming photometric galaxy surveys is contingent on our ability to obtain redshift estimates for large numbers of faint galaxies. In the absence of spectroscopically confirmed redshifts, broad-band photometric redshift point estimates (photo-$z$s) have been superseded by photo-$z$ probability density functions (PDFs) that encapsulate their nontrivial uncertainties. Initial applications of photo-$z$ PDFs in weak gravitational lensing studies of cosmology have obtained the redshift distribution function $\mathcal{N}(z)$ by employing computationally straightforward stacking methodologies that violate the laws of probability. In response, mathematically self-consistent models of varying complexity have been proposed in an effort to answer the question, “What is the right way to obtain the redshift distribution function $\mathcal{N}(z)$ from a catalog of photo-$z$ PDFs?” This paper aims to motivate adoption of such principled methods by addressing the contrapositive of the more common presentation of such models, answering the question, “Under what conditions do traditional stacking methods successfully recover the true redshift distribution function $\mathcal{N}(z)$?” By placing stacking in a rigorous mathematical environment, we identify two such conditions: those of perfectly informative data and perfectly informative prior information. Stacking has maintained its foothold in the astronomical community for so long because the conditions in question were only weakly violated in the past. These conditions, however, will be strongly violated by future galaxy surveys. We therefore conclude that stacking must be abandoned in favor of mathematically supported methods in order to advance observational cosmology.

Ultralight bosons, which are predicted in a variety of beyond-Standard-Model scenarios as dark-matter candidates, can trigger superradiant instability around spinning black holes. This instability gives rise to oscillating boson condensates, which then dissipate through the emission of nearly monochromatic gravitational waves. Such systems are promising sources for current and future gravitational-wave detectors. In this work, we consider minimally coupled, massive vector bosons, which can produce a significantly stronger gravitational-wave signal compared to the scalar case. We adopt recently obtained numerical results for the gravitational-wave flux, and astrophysical models of black-hole populations that include both isolated black holes and binary merger remnants, to compute and study in detail the stochastic gravitational-wave background emitted by these sources. Using a Bayesian framework, we search for such a background signal emitted using data from the first and second observing runs of Advanced LIGO. We find no evidence for such a signal. Therefore, the results allow us to constrain minimally coupled vector fields with masses in the range $0.8\times {10}^{-13}\mathrm{eV}\le m_b\le 6.0\times {10}^{-13}\mathrm{eV}$ at 95% credibility, assuming optimistically that the dimensionless spin distribution for the isolated black-hole population is uniform in the range [0, 1]. With more pessimistic assumptions, a narrower range around $m_b\approx {10}^{-13}\mathrm{eV}$ can still be excluded as long as the upper end of the uniform distribution for dimensionless black-hole spin is $\gtrsim 0.2$.

A set of unified relativistic mean-field equations of state for hyperonic compact stars recently built in [M. Fortin, Ad. R. Raduta, S. Avancini, and C. Providência, Phys. Rev. D 101, 034017 (2020)] is used to study the thermal evolution of nonmagnetized and nonrotating spherically-symmetric isolated and accreting neutron stars under different hypothesis concerning proton $S$-wave superfluidity. These equations of state have been obtained in the following way: the slope of the symmetry energy is in agreement with experimental data; the coupling constants of $\mathrm{\Lambda }$ and $\mathrm{\Xi }$-hyperons are determined from experimental hypernuclear data; uncertainties in the nucleon-$\mathrm{\Sigma }$ interaction potential are accounted for; current constraints on the lower bound of the maximum neutron star mass are satisfied. Within the considered set of equations of state, the presence of hyperons is essential for the description of the cooling/heating curves. One of the conclusions we reach is that the criterion of best agreement with observational data leads to different equations of states and proton $S$-wave superfluidity gaps when applied separately for isolated neutron stars and accreting neutron stars in quiescence. This means that at least in one situation the traditional simulation framework that we employ is not complete and/or the equations of state are inappropriate. Another result is that, considering equations of state which do not allow for nucleonic dUrca or allow for it only in very massive NS, the low luminosity of SAX J1808 requires a repulsive $\mathrm{\Sigma }$-hyperon potential in symmetric nuclear matter in the range $U_{\mathrm{\Sigma }}^{(N)}\approx 10–30\mathrm{MeV}$. This range of values for $U_{\mathrm{\Sigma }}^{(N)}$ is also supported by the criterion of best agreement with all available data from INS and XRT.

In this work, we investigate the axionlike particle (ALP)-photon oscillation effect in the spectra of the blazar Markarian 421 (Mrk 421) using 4.5 years of the Astrophysical Radiation with Ground-based Observatory at YangBaJing (ARGO-YBJ) and Fermi Large Area Telescope (Fermi-LAT) data. These data are collected during the common operation time, which cover ten activity phases of Mrk 421. No significant ALP-photon oscillation effect is confirmed. On the other hand, not all the observations of the ten phases can be individually used to set the 95% confidence level (C.L.) constraint on the ALP parameter space. However, the constraint can be significantly improved if the analyses for the ten phases are combined. We find that the upper limit at 95% C.L. on the ALP-photon coupling $g_{a\gamma }$ set by the ARGO-YBJ and Fermi-LAT observations of Mrk 421 is within $\sim [2\times {10}^{-11},6\times {10}^{-11}]{\mathrm{GeV}}^{-1}$ for the ALP mass of $\sim 5\times {10}^{-10}\mathrm{eV}\lesssim m_a\lesssim 5\times {10}^{-7}\mathrm{eV}$.

The exciting possibility of detecting supernova, solar, and atmospheric neutrinos with coherent neutrino-nucleus scattering detectors is within reach, opening up new avenues to probe new physics. We explore the possibility of constraining nonstandard coherent neutrino-nucleus scattering through astrophysical neutrinos. Sensitivity bounds on the mass and coupling of the new mediator are obtained by inspecting the modifications induced by the new interaction on the recoil rate observable in the upcoming RES-NOVA and DARWIN facilities. Under the assumption of optimal background tagging, the detection of neutrinos from a galactic supernova burst, or one-year exposure to solar and atmospheric neutrinos, will place the most stringent bounds for mediator couplings $g\gtrsim {10}^{-5}$ and mediator masses between 1 and 100 MeV. A similar, but slightly improved, potential to COHERENT will be provided for larger mediator masses. In particular, RES-NOVA and DARWIN may potentially provide one order of magnitude tighter constraints than XENON1T on the mediator coupling. Nonstandard coherent neutrino-nucleus scattering may also force neutrinos to be trapped in the supernova core; this argument allows us to probe the region of the parameter space with $g\gtrsim {10}^{-4}$, which is currently excluded by other coherent neutrino-nucleus scattering facilities or other astrophysical and terrestrial constraints.

We investigate the pure annihilation type radiative $B$ meson decays $B^0\to \varphi \gamma$ and $B_s\to {\rho }^0(\omega )\gamma$ in the soft-collinear effective theory. We consider three types of contributions to the decay amplitudes, including the direct annihilation topology, the contribution from the electromagnetic penguin operator, and the contribution of the neutral vector meson mixing. The numerical analysis shows that the decay amplitudes are dominated by the $\omega -\varphi$ mixing effect in the $B^0\to \varphi \gamma$ and $B_s\to \omega \gamma$ modes. The corresponding decay branching ratios are enhanced about 3 orders of magnitude relative to the pure annihilation type contribution in these two decay channels. The decay rate of $B_s\to {\rho }^0\gamma$ is much smaller than that of $B_s\to \omega \gamma$ because of the smaller ${\rho }^0-\varphi$ mixing. The predicted branching ratios $⟨B(B^0\to \varphi \gamma )⟩=(3.96_{-1.45}^{+1.67})\times {10}^{-9}$ and $⟨B(B_s\to \omega \gamma )⟩=(1.99_{-0.70}^{+0.81})\times {10}^{-7}$ are to be tested by the Belle-II and LHCb experiments.

The weakly interacting massive particle (WIMP) paradigm is one of the most compelling scenarios for particle dark matter (DM). We show in this paper that a high energy muon collider can make decisive statements about the WIMP DM, and this should serve as one of its main physics driver cases. We demonstrate this by employing the DM as the lightest member of an electroweak (EW) multiplet, which is a simple, yet one of the most challenging WIMP scenarios given its minimal collider signature and high thermal target mass scale of 1–23 TeV. We perform a first study of the reach of high energy muon colliders, focusing on the simple, inclusive, and conservative signals with large missing mass, through the mono-photon, vector boson fusion di-muon and a novel mono-muon channel. Using these inclusive signals, it is possible to cover the thermal targets of doublet and triplet with a 10 TeV muon collider. Higher energies, 14 TeV–75 TeV, would ensure a $5\sigma$ reach above the thermal targets for the higher EW multiplets. We also estimate the reach of a search for disappearing tracks, demonstrating the potential significant enhancement of the sensitivity.

We investigate the potential of future data from next generation long-baseline neutrino experiments, DUNE and T2HK and the upcoming reactor experiment JUNO in constraining neutral current nonstandard neutrino interactions (NSI) parameters. JUNO is going to provide the most precise measurements of solar neutrino oscillation parameters as well as determining the neutrino mass ordering. We study how the results of JUNO combined with those of long-baseline neutrino experiments such as DUNE and T2HK can help to determine oscillation parameters and constrain NSI parameters. We present excluded regions in NSI parameter space, ${\epsilon }_{\alpha \beta }$ assuming Standard Model (SM) as the null hypothesis. We further explore the correlations between the NSI parameters and the $CP$-violation phase.

We propose the use of silicon carbide (SiC) for direct detection of sub-GeV dark matter. SiC has properties similar to both silicon and diamond but has two key advantages: (i) it is a polar semiconductor which allows sensitivity to a broader range of dark matter candidates; and (ii) it exists in many stable polymorphs with varying physical properties and hence has tunable sensitivity to various dark matter models. We show that SiC is an excellent target to search for electron, nuclear and phonon excitations from scattering of dark matter down to 10 keV in mass, as well as for absorption processes of dark matter down to 10 meV in mass. Combined with its widespread use as an alternative to silicon in other detector technologies and its availability compared to diamond, our results demonstrate that SiC holds much promise as a novel dark matter detector.

In the paper, we calculate the fragmentation functions for a quark to fragment into a spin-singlet quarkonium, where the flavor of the initial quark is different from that of the constituent quark in the quarkonium. The ultraviolet divergences in the phase space integral are removed through the operator renormalization under the modified minimal subtraction scheme. The fragmentation function $D_{q\to {\eta }_Q}(z,{\mu }_F)$ is expressed as a two-dimensional integral. Numerical results for the fragmentation functions of a light quark or a bottom quark to fragment into the ${\eta }_c$ are presented. As an application of those fragmentation functions, we study the processes $Z\to {\eta }_c+q\overline{q}g(q=u,d,s)$ and $Z\to {\eta }_c+b\overline{b}g$ under the fragmentation and the direct nonrelativistic QCD approaches.

We estimate in medium properties of axion i.e., its mass and self-coupling within a three flavor Polyakov loop extended Nambu–Jona-Lasinio (PNJL) model with Kobayashi-Maskawa-t’Hooft determinant interaction. We also estimate the topological susceptibility of strong interaction within the same model. It is observed that (statistical) confinement effects simulated by Polyakov loop potential play an important role in the estimation of all these quantities, particularly, near the critical temperature. Both the mass and the self-coupling of the axion get correlated with the chiral and deconfinement transition. The results for all these quantities obtained within the PNJL model is compared with chiral perturbation theory, Nambu–Jona-Lasinio (NJL) model and lattice QCD simulation results wherever available. The results for properties of axions at finite baryon densities are also presented.

We study the mass/energy structure of the bound state of hadrons in two-dimensional quantum chromodynamics in the large number of color limit (${}^{\prime }t$ Hooft model). We analyze separately the contributions from the traceless and trace part of the energy-momentum tensor, and show that the masses are related to the matrix elements of the scalar charge and Coulomb energy. We derive the light-front sum rules for the scalar charge and Coulomb energy, expressed in terms of the light-front wave functions, and find that they are regular at $x=0$ without the delta function contribution. We also consider the result for the massless Goldstone boson, as well as the structure of the gravitational form factors of the bound meson states.

Brownian thermal noise associated with highly reflective mirror coatings is a fundamental limit for several precision experiments, including gravitational-wave detectors. Recently, there has been a worldwide effort to find mirror coatings with improved thermal noise properties that also fulfill strict optical requirements such as low absorption and scatter. We report on the optical and mechanical properties of ion-beam-sputtered niobia and titania-niobia thin films, and we discuss application of such coatings in current and future gravitational-wave detectors. We also report an updated direct coating thermal noise measurement of the HR coatings used in Advanced LIGO and Advanced Virgo, and the observation of a discrepancy between ring-down measurements and thermal-noise estimations of mechanical loss in highly reflective mirror coatings. This discrepancy might be ascribed either to a dissipation of the silica layers considerably higher than expected or to an unexplained excess loss of stacked layers.