We compute the next-to-leading order (NLO) impact factor for inclusive $\mathrm{photon}+\mathrm{dijet}$ production in electron-nucleus ($\mathrm{e}+\mathrm{A}$) deeply inelastic scattering (DIS) at small $x$. An important ingredient in our computation is the simple structure of “shock wave” fermion and gluon propagators. This allows one to employ standard momentum space Feynman diagram techniques for higher order computations in the Regge limit of fixed $Q^2\gg {\mathrm{\Lambda }}_{\mathrm{QCD}}^2$ and $x\to 0$. Our computations in the color glass condensate (CGC) effective field theory include the resummation of all-twist power corrections $Q_s^2/Q^2$, where $Q_s$ is the saturation scale in the nucleus. We discuss the structure of ultraviolet, collinear and soft divergences in the CGC, and extract the leading logs in $x$; the structure of the corresponding rapidity divergences gives a nontrivial first principles derivation of the JIMWLK renormalization group evolution equation for multiparton lightlike Wilson line correlators. Explicit expressions are given for the $x$-independent $O({\alpha }_s)$ contributions that constitute the NLO impact factor. These results, combined with extant results on NLO JIMWLK evolution, provide the ingredients to compute the inclusive photon $+$ dijet cross section at small $x$ to $O({\alpha }_s^3\ln (x))$. First results for the NLO impact factor in inclusive dijet production are recovered in the soft photon limit. A byproduct of our computation is the LO $\text{photon}+3$ jet (quark-antiquark-gluon) cross section.

We estimate here the electrical and Hall conductivity using a quasiparticle approach for quark matter. We use a Boltzmann kinetic approach in the presence of external magnetic field. We confront the results of model calculations with lattice QCD simulations for vanishing magnetic field. In general, electrical conductivity decreases with magnetic field. The Hall conductivity on the other hand can show a nonmonotonic behavior with magnetic field due to an intricate interplay of behavior of relaxation time and strength of the magnetic field. We argue for vanishing quark chemical potential Hall conductivity vanishes and quark gluon plasma with finite quark chemical potential can show Hall effect. Both electrical conductivity and Hall conductivity increase with increasing quark chemical potential.

We present a study of the $N^{*}(1535)$ resonance electroexcitation in a soft-wall AdS/QCD model. Both the transverse $A_{1/2}^p$ and longitudinal $S_{1/2}^p$ helicity amplitudes are calculated resulting in good agreement with data and with the MAID parametrization.

The production of the Higgs boson in photon-photon interactions with proton and nucleus beams at three planned or proposed future CERN colliders—the high-luminosity Large Hadron Collider (HL-LHC), the high-energy LHC (HE-LHC), and the Future Circular Collider (FCC)—is studied. The cross sections for the process $\mathrm{AA}\stackrel{\gamma \gamma }{\to }(\mathrm{A})\mathrm{H}(\mathrm{A})$, with the ions A surviving the interaction and the Higgs scalar exclusively produced, are computed with madgraph 5 modified to include the corresponding elastic $\gamma$ fluxes, for Pb-Pb, Xe-Xe, Kr-Kr, Ar-Ar, O-O, p-Pb, and p-p over the nucleon-nucleon collision energy range $\sqrt{s_{\mathrm{NN}}}\approx 3–100\mathrm{TeV}$. Simulations of the $\gamma \gamma \to \mathrm{H}\to \mathrm{b}\overline{\mathrm{b}}$ decay mode—including realistic (mis)tagging and reconstruction efficiencies for the final-state b-jets, as well as appropriate kinematical selection criteria to reduce the similarly computed $\gamma \gamma \to \mathrm{b}\overline{\mathrm{b}},\mathrm{c}\overline{\mathrm{c}},\mathrm{q}\overline{\mathrm{q}}$ continuum backgrounds—have been carried out. Taking into account the expected luminosities for all systems, the yields, and significances for observing the Higgs boson in ultraperipheral collisions (UPCs) are estimated. At the HL-LHC and HE-LHC, the colliding systems with larger Higgs significance are Ar-Ar (6.3 TeV) and Kr-Kr (12.5 TeV), respectively, but $3\sigma$ evidence for two-photon Higgs production would require 200 and 30 times larger integrated luminosities than those planned today at both machines. Factors of 10 can be gained by running for a year, rather than the typical 1-month heavy-ion LHC operation, but the process will likely remain unobserved until a higher energy hadron collider, such as the FCC, is built. In the latter machine, the $5\sigma$ observation of Higgs production in UPCs is feasible in just the first nominal run of Pb-Pb and p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=39$ and 63 TeV, respectively.

In addition to the next generation of beam-based neutrino experiments and their associated detectors, a number of intense, low-energy neutrino production sources from decays at rest will be in operation. In this work, we explore the physics opportunities with decay-at-rest neutrinos for complementary measurements of oscillation parameters at long baselines. The J-PARC Spallation Neutron Source, for example, will generate neutrinos from a variety of decay-at-rest (DAR) processes, specifically those of pions, muons, and kaons. Other proposed sources will produce large numbers of stopped pions and muons. We demonstrate the ability of the upcoming Hyper-Kamiokande experiment to detect the monochromatic kaon decay-at-rest neutrinos from J-PARC after they have traveled several hundred kilometers and undergone oscillations. This measurement will serve as a valuable cross-check in constraining our understanding of neutrino oscillations in a new regime of neutrino energy and baseline length. We also study the expected event rates from pion and muon DAR neutrinos in liquid argon and water detectors and their sensitivities to the charge-parity- ($CP$) violating phase ${\delta }_{\mathit{CP}}$.

In a previous paper, we proposed a probability interpretation for higher genus amplitudes of BMN (Berenstein-Maldacena-Nastase) strings in a pp-wave background with infinite negative curvature. This provides a natural definition of the entropy of a BMN string as the Shannon entropy of its corresponding probability distribution. We prove a universal upper bound that the entropy grows at most logarithmically in the strong string coupling limit. We also study the entropy by numerical methods and discuss some interesting salient features.

We show that the homogeneous, massless Einstein-Vlasov system with toroidal spatial topology and diagonal Bianchi type I symmetry for initial data close to isotropic data isotropizes towards the future and in particular asymptotes to a radiative Einstein-de Sitter model. We use an energy method to obtain quantitative estimates on the rate of isotropization in this class of models.

Gravitational wave echoes may imply physics beyond general relativity; however, several approaches to searching for echoes require fitting the data to toy templates that are not physically motivated. Here, I create a procedure that outputs a more realistic form for echoes, starting from initial conditions, by calculating the modulated transfer function.

We consider the escape probability of a photon emitted from the innermost stable circular orbit (ISCO) of a rapidly rotating black hole. As an isotropically emitting light source on a circular orbit reduces its orbital radius, the escape probability of a photon emitted from it decreases monotonically. The escape probability evaluated at the ISCO also decreases monotonically as the black hole spin increases. When the dimensionless Kerr parameter $a$ is at the Thorne limit $a=0.998$, the escape probability from the ISCO is 58.8%. In the extremal case $a=1$, even if the orbital radius of the light source is arbitrarily close to the ISCO radius, which coincides with the horizon radius, the escape probability remains at 54.6%. We also show that such photons that have escaped from the vicinity of the horizon reach infinity with sufficient energy to be potentially observed because Doppler blueshift due to relativistic beaming can overcome the gravitational redshift. Our findings indicate that signs of the near-horizon physics of a rapidly rotating black hole will be detectable on the edge of its shadow.

The Gibbons-Werner method where the Gauss-Bonnet theorem is applied to study the gravitational deflection angle has received much attention recently. In this paper, we study the equivalence of the Gibbons-Werner method to the standard geodesics method, and it is shown that the geodesics method can be derived with the Gibbons-Werner method, for the asymptotically flat case. In the geodesics method, the gravitational deflection angle of the particle depends entirely on the geodesic curvature of the particle ray in the Euclidean space. The gravitational deflection of light in Kerr-Newman spacetime is calculated by different technologies under the Gibbons-Werner framework, as an intuitive example to show the equivalence.

Here we discuss an effect of dephasing induced by a weak gravitational field on the collective radiation dynamics of an atomic system in timed single-photon Dicke states. We show that a photon absorbed by the stationary system of randomly placed stationary atoms is no longer spontaneously emitted in the direction of the impinging photon. Gravity leads to broadening of the angular distribution of emission.

It is standard practice to study the lensing of gravitational waves (GW) using the geometric optics regime. However, in many astrophysical configurations this regime breaks down as the wavelength becomes comparable to the Schwarzschild radius of the lens. We revisit the lensing of GW including corrections beyond geometric optics. We propose a perturbative method for calculating these corrections simply solving first order decoupled differential equations. We study the behavior of a single ray and find that the polarization plane defined in geometric optics is smeared due to diffraction effects, which leads to the rise of apparent vector and scalar polarization modes. We analyze how these modes depend on the observer choice, and we study the impact of diffraction on the pseudostress energy momentum tensor of the gravitational field.

It has been pointed out that matter bounce cosmology driven by a k-essence field cannot satisfy simultaneously the observational bounds on the tensor-to-scalar ratio and non-Gaussianity of the curvature perturbation. In this paper, we show that this is not the case in more general scalar-tensor theories. To do so, we evaluate the power spectra and the bispectra of scalar and tensor perturbations on a general contracting background in the Horndeski theory. We then discuss how one can discriminate contracting models from inflation based on non-Gaussian signatures of tensor perturbations.

The gravitational waves (GWs) from the merger events of binary black hole (BH-BH) and binary neutron star (NS-NS) have been detected by LIGO-Virgo (O1 and O2). Besides, GWs from the NS-BH mergers have been recently reported and might be hopefully confirmed in the near future. The mass distributions of these merger events are poorly understood now; thus, LIGO-Virgo adopted a simple cut rule for chirp mass ($\mathcal{M}$) to distinguish the GW event candidates: $\mathcal{M}<2.1M_{\odot }$ for NS-NS, $2.1M_{\odot }<\mathcal{M}<4.35M_{\odot }$ for NS-BH, and $\mathcal{M}>4.35M_{\odot }$ for BH-BH. We tested its validity by simulating the chirp mass ($\mathcal{M}$) distributions in two synthetic models, i.e., Model Galaxy and Model LIGO, in which the masses of BHs and NSs are observed by the electromagnetic spectrum observations in our Galaxy and inferred by LIGO-Virgo detection (O1 and O2), respectively. The simulation shows that it is unsuitable for Model LIGO due to the BHs inferred by LIGO-Virgo are usually bigger than those in our Galaxy, and $\mathcal{M}$ of NS-BH events would distribute in the range of $2.1M_{\odot }<\mathcal{M}<7.3M_{\odot }$, which partially overlaps with those of BH-BH events. Therefore, we suggest that the new searching round of LIGO-Virgo (e.g., O3) should carefully seek out the underlying NS-BH candidates in the range of $2.1M_{\odot }<\mathcal{M}<7.3M_{\odot }$.

The recent measurements on $b\to s{\ell }^{+}{\ell }^{-}$ processes suggest the existence of lepton-flavor-universality breaking new physics. In this work, we have explored the possibility of explaining these data by sneutrinos in the $R$-parity violating minimal supersymmetric standard model. We study the light sneutrinos, of order 1 TeV, and suppose that the rest of the sfermions are much heavier than them. This setup can solve the $b\to s{\mu }^{+}{\mu }^{-}$ anomaly well, and it is almost unconstrained by other related processes, such as $B_s-{\overline{B}}_s$ mixing, as well as $B_s^0\to {\tau }^{+}{\tau }^{-}$, $B^{+}\to K^{+}{\tau }^{+}{\tau }^{-}$, $B_s^0\to {\tau }^{\pm }{\mu }^{\mp }$, $B^{+}\to K^{+}{\tau }^{\pm }{\mu }^{\mp }$, and $B\to K^{(*)}\nu \overline{\nu }$ decays.

The domain wall problem and the isocurvature problem restrict possible combinations of axion models and inflation models. In this paper, we consider a new mechanism which solves those problems by dynamics of multiple scalar fields during/after inflation. The mechanism makes axion models with a nontrivial domain wall number compatible with inflation models with a large Hubble parameter, $H_I\gg 10^{7–8}\mathrm{GeV}$. The isocurvature problem is also avoided in the mechanism.

The production of a quarkonium pair in exclusive and diffractive processes in $pp$ collisions at the LHC and FCC energies is investigated. We consider the $J/\mathrm{\Psi }J/\mathrm{\Psi }$ and $\mathrm{\Upsilon }\mathrm{\Upsilon }$ production in these processes and present predictions for the transverse momentum and rapidity distributions considering the kinematical ranges expected to be covered by central and forward detectors. Results for the cross sections are also presented. Our results indicate that the double $J/\mathrm{\Psi }$ production is dominated by the exclusive process, while the double $\mathrm{\Upsilon }$ production receives a large contribution of the diffractive process. The impact of modeling of the gap survival factor on our predictions is discussed.

We derive the four-fold angular distribution for the semileptonic decay $\overline{B}\to D_2^{*}(\to D\pi )\ell \overline{\nu }$ where $D_2^{*}(2460)$ is a tensor meson. We start with the most general beyond the Standard Model (SM) dimension-six effective Hamiltonian which comprises (axial-)vector, (pseudo)scalar, and tensor operators for both quark and lepton currents, and it also includes the right-handed neutrinos. The decay can be described by 16 transversity amplitudes and it provides a multitude of observables which can be extracted from data. We investigate the observables in the context of the SM and the new physics scenarios which can explain the intriguing discrepancies observed in the $b\to c\tau \overline{\nu }$ data.

Theoretical predictions for elastic neutrino-electron scattering have no hadronic or nuclear uncertainties at leading order making this process an important tool for normalizing neutrino flux. However, the process is subject to large radiative corrections that differ according to experimental conditions. In this paper, we collect new and existing results for total and differential cross sections accompanied by radiation of one photon, $\nu e\to \nu e(\gamma )$. We perform calculations within the Fermi effective theory and provide analytic expressions for the electron energy spectrum and for the total electromagnetic energy spectrum as well as for double- and triple-differential cross sections with respect to electron energy, electron angle, photon energy, and photon angle. We discuss illustrative applications to accelerator-based neutrino experiments and provide the most precise up-to-date values of neutrino-electron scattering cross sections. We present an analysis of theoretical error, which is dominated by the $\sim 0.2\%–0.4\%$ uncertainty of the hadronic correction. We also discuss how searches for new physics can be affected by radiative corrections.

We report the result for a search for the leptonic decay of $B^{+}\to {\mu }^{+}{\nu }_{\mu }$ using the full Belle dataset of $711{\mathrm{fb}}^{-1}$ of integrated luminosity at the $\mathrm{\Upsilon }(4S)$ resonance. In the Standard Model leptonic $B$-meson decays are helicity and Cabibbo-Kobayashi-Maskawa suppressed. To maximize sensitivity an inclusive tagging approach is used to reconstruct the second $B$ meson produced in the collision. The directional information from this second $B$ meson is used to boost the observed $\mu$ into the signal $B$-meson rest frame, in which the $\mu$ has a monochromatic momentum spectrum. Though its momentum is smeared by the experimental resolution, this technique improves the analysis sensitivity considerably. Analyzing the $\mu$ momentum spectrum in this frame we find $\mathcal{B}(B^{+}\to {\mu }^{+}{\nu }_{\mu })=(5.3\pm 2.0\pm 0.9)\times {10}^{-7}$ with a one-sided significance of 2.8 standard deviations over the background-only hypothesis. This translates to a frequentist upper limit of $\mathcal{B}(B^{+}\to {\mu }^{+}{\nu }_{\mu })<8.6\times {10}^{-7}$ at 90% confidence level. The experimental spectrum is then used to search for a massive sterile neutrino, $B^{+}\to {\mu }^{+}N$, but no evidence is observed for a sterile neutrino with a mass in a range of 0–1.5 GeV. The determined $B^{+}\to {\mu }^{+}{\nu }_{\mu }$ branching fraction limit is further used to constrain the mass and coupling space of the type II and type III two-Higgs-doublet models.