We revisit the alternative left-right symmetric model, motivated by the superstring-inspired $E_6$ model. We systematically analyze the constraints imposed by theoretical and experimental bounds on the parameter space of this class of models. We perform a comprehensive analysis of the Higgs sector and show that three neutral $CP$-even and two $CP$-odd Higgs bosons in addition to two charged Higgs bosons can be light, of $\mathcal{O}(100)\mathrm{GeV}$. We emphasize that the predictions of this model for the signal strengths of Higgs decays are consistent with the standard model expectations. We also explore discovery signatures of the exotic down-type quark, which is one of the salient predictions of this model.

Higgs boson properties could be studied with a high accuracy at a muon collider via the $s$-channel resonant production. We consider the situation where the center-of-mass energy of the muon collider is off the resonance above the Higgs mass. We discuss the discovery potential for a generic heavy Higgs boson and compare different production mechanisms, including the “radiative return,” $Z$-boson associated production and heavy Higgs pair production. These production mechanisms do not sensitively rely on a priori knowledge of the heavy Higgs boson mass. We include various types of two-Higgs-doublet models for the comparison. We conclude that the radiative return process could provide an important option for both the heavy Higgs discovery and direct measurement of invisible decays at a high energy muon collider.

We investigate the temperature ($T$) dependence of quark number densities ($n_q$) at imaginary and real chemical potential ($\mu$) by using $N_f=2$ lattice QCD and the hadron resonance gas (HRG) model. Quark number densities are calculated at imaginary $\mu$ with lattice QCD (LQCD) on an $8^2\times 16\times 4$ lattice with the clover-improved $N_f=2$ Wilson fermion action and the renormalization-group-improved Iwasaki gauge action. The results are consistent with the previous results of the staggered-type quark action. The $n_q$ obtained are extrapolated to real $\mu$ by assuming the Fourier series for the confinement region and the polynomial series for the deconfinement region. The extrapolated results are consistent with the previous results of the Taylor expansion method for the reweighting factor. The upper bound $(\mu /T{)}_{\max }$ of the region where the extrapolation is considered to be reliable is estimated for each temperature $T$. We test whether $T$ dependence of nucleon and $\mathrm{\Delta }$-resonance masses can be determined from LQCD data on $n_q$ at imaginary $\mu$ by using the HRG model. In the test calculation, nucleon and $\mathrm{\Delta }$-resonance masses reduce by about 10% in the vicinity of the pseudocritical temperature.

Within the framework of the effective Lagrangian approach, we perform a thorough analysis of the $J/\psi \to P\gamma ({\gamma }^{*})$, $J/\psi \to VP$, $V\to P\gamma ({\gamma }^{*})$, $P\to V\gamma ({\gamma }^{*})$, and $P\to \gamma \gamma ({\gamma }^{*})$ processes, where $V$ stands for light vector resonances, $P$ stands for light pseudoscalar mesons, and ${\gamma }^{*}$ subsequently decays into lepton pairs. The processes with light pseudoscalar mesons $\eta$ and ${\eta }^{\prime }$ are paid special attention to and the two-mixing-angle scheme is employed to describe their mixing. The four mixing parameters, both in singlet-octet and quark-flavor bases, are updated in this work. We confirm that the $J/\psi \to \eta ({\eta }^{\prime }){\gamma }^{(*)}$ processes are predominantly dominated by the $J/\psi \to {\eta }_c{\gamma }^{*}\to \eta ({\eta }^{\prime }){\gamma }^{(*)}$ mechanism. Predictions for the $J/\psi \to P{\mu }^{+}{\mu }^{-}$ are presented. A detailed discussion on the interplay between electromagnetic and strong transitions in the $J/\psi \to VP$ decays is given.

We consider some contributions to rare processes in B meson decays from a dark sector containing two light unstable scalars, with large couplings to each other and small mixings with Standard Model Higgs scalars. We show that existing constraints allow for an exotic contribution to high multiplicity final states with a branching fraction as large as $\mathcal{O}({10}^{-4})$ and that exotic particles could appear as narrow resonances or long lived particles which are mainly found in high multiplicity final states from B decays.

Kinematic distributions from an inclusive sample of $1.41\times {10}^6$ charged-current ${\nu }_{\mu }$ interactions on iron, obtained using the MINOS near detector exposed to a wide-band beam with peak flux at 3 GeV, are compared to a conventional treatment of neutrino scattering within a Fermi gas nucleus. Results are used to guide the selection of a subsample enriched in quasielastic ${\nu }_{\mu }\mathrm{Fe}$ interactions, containing an estimated 123,000 quasielastic events of incident energies $1<E_{\nu }<8\mathrm{GeV}$, with $⟨E_{\nu }⟩=2.79\mathrm{GeV}$. Four additional subsamples representing topological and kinematic sideband regions to quasielastic scattering are also selected for the purpose of evaluating backgrounds. Comparisons using subsample distributions in four-momentum transfer $Q^2$ show the Monte Carlo model to be inadequate at low $Q^2$. Its shortcomings are remedied via inclusion of a $Q^2$-dependent suppression function for baryon resonance production, developed from the data. A chi-square fit of the resulting Monte Carlo simulation to the shape of the $Q^2$ distribution for the quasielastic-enriched sample is carried out with the axial-vector mass $M_A$ of the dipole axial-vector form factor of the neutron as a free parameter. The effective $M_A$ which best describes the data is ${1.23}_{-0.09}^{+0.13}{(\text{fit})}_{-0.15}^{+0.12}(\text{syst})\mathrm{GeV}$.

We report the measurement of the flux-averaged antineutrino neutral current elastic scattering cross section ($d{\sigma }_{\overline{\nu }N\to \overline{\nu }N}/d{Q}^2$) on ${\mathrm{CH}}_2$ by the MiniBooNE experiment using the largest sample of antineutrino neutral current elastic candidate events ever collected. The ratio of the antineutrino to neutrino neutral current elastic scattering cross sections and a ratio of the antineutrino neutral current elastic to antineutrino charged current quasielastic cross sections are also presented.

We search for the decay $B_s^0\to \gamma \gamma$ and measure the branching fraction for $B_s^0\to \varphi \gamma$ using $121.4{\mathrm{fb}}^{-1}$ of data collected at the $\mathrm{\Upsilon }(5S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. The $B_s^0\to \varphi \gamma$ branching fraction is measured to be $(3.6\pm 0.5(\text{stat})\pm 0.3(\text{syst})\pm 0.6(f_s))\times 10^{-5}$, where $f_s$ is the fraction of $B_s^{(*)}{\overline{B}}_s^{(*)}$ in $b\overline{b}$ events. Our result is in good agreement with the theoretical predictions as well as with a recent measurement from LHCb. We observe no statistically significant signal for the decay $B_s^0\to \gamma \gamma$ and set a 90% confidence-level upper limit on its branching fraction at $3.1\times 10^{-6}$. This constitutes a significant improvement over the previous result.

We analyze the conservative evolution of spinning compact binaries to second post-Newtonian (2PN) order accuracy, with leading-order spin-orbit, spin-spin and mass quadrupole-monopole contributions included. As a main result we derive a closed system of first-order differential equations in a compact form, for a set of dimensionless variables encompassing both orbital elements and spin angles. These evolutions are constrained by conservation laws holding at 2PN order. As required by the generic theory of constrained dynamical systems we perform a consistency check and prove that the constraints are preserved by the evolution. We apply the formalism to show the existence of chameleon orbits, whose local, orbital parameters evolve from elliptic (in the Newtonian sense) near pericenter, towards hyperbolic at large distances. This behavior is consistent with the picture that general relativity predicts stronger gravity at short distances than Newtonian theory does.

It has been shown that gravitational fields produced by realistic classical-matter distributions can force quantum vacuum fluctuations of some nonminimally coupled free scalar fields to undergo a phase of exponential growth. The consequences of this unstable phase for the background spacetime have not been addressed so far due to known difficulties concerning backreaction in semiclassical gravity. It seems reasonable to believe, however, that the quantum fluctuations will “classicalize” when they become large enough, after which backreaction can be treated in the general-relativistic context. Here we investigate the emergence of a classical regime out of the quantum field evolution during the unstable phase. By studying the appearance of classical correlations and loss of quantum coherence, we show that by the time backreaction becomes important the system already behaves classically. Consequently, the gravity-induced instability leads naturally to initial conditions for the eventual classical description of the backreaction. Our results give support to previous analyses which treat classically the instability of scalar fields in the spacetime of relativistic stars, regardless of whether the instability is triggered by classical or quantum perturbations.

We apply the convolved Lagrangian perturbation theory (CLPT) formalism, in which one can express the matter density power spectrum in terms of integrals over a function of cumulants of the displacement field, allowing for a resummation of the terms, to evaluate the full one loop power spectrum. We keep the cumulants up to third order, extending the Zel’dovich approximation and providing the power spectrum analogous to the calculations recently performed for the correlation function. We compare the results to the N-body simulations and to the Lagrangian perturbation simulations up to the second order. We find that the analytic calculations are in a good agreement with the Lagrangian perturbation theory simulations, but when compared to full N-body simulations, we find that, while one loop calculations improve upon the Zel’dovich approximation in the power spectrum, they still significantly lack power. As found previously in the correlation function one loop CLPT improves slightly against Zel’dovich above $30\mathrm{Mpc}/\mathrm{h}$ but is actually worse than Zel’dovich below that. We investigate the deficiencies of the CLPT approach and argue that main problem of CLPT is its inability to trap particles inside dark matter halos, which leads to an overestimate of the small-scale power of the displacement field and to an underestimate of the small-scale power from one halo term effects. We model this using the displacement field damped at a nonlinear scale (CLPTs). To explore this in more detail we decompose the power spectrum and correlation function into three additive components: Zel’dovich, residual baryon acoustic oscillation (BAO) wiggle, and residual broadband. One loop CLPT predicts small modifications to BAO wiggles that are enhanced in CLPTs, with up to 5% corrections to correlation function around BAO scale. For the residual broadband contribution CLPTs improves the broadband power in the power spectrum but is still insufficient compared to simulations and makes the correlation function agreement worse than CLPT.

In this paper, we investigate the stability of the Einstein static universe sourced by a single perfect fluid with a constant equation of state against homogeneous and inhomogeneous scalar perturbations in the context of $f(G)$-modified Gauss-Bonnet gravity. We find that for a spatially closed universe inhomogeneous scalar perturbations do not allow a stable Einstein static solution, although homogeneous ones do, and for a spatially open universe the Einstein static solution is unstable against either homogeneous or inhomogeneous scalar perturbations. As a result, the emergent scenario that aims to resolve the big bang singularity problem cannot be successfully implemented in the modified Gauss-Bonnet theory.

Quantum electrodynamics (QED) comprises virtual particle production and thus gives rise to a refractive index of the vacuum larger than unity in the presence of a magnetic field. This predicted effect has not been measured to date, even after considerable effort of a number of experiments. It has been proposed by other authors to possibly use gravitational wave detectors for such vacuum QED measurements, and we give this proposal some new consideration in this paper. In particular, we look at possible source field magnet designs and further constraints on the implementation at a gravitational wave detector. We conclude that such an experiment seems to be feasible with permanent magnets, yet still challenging in its implementation.

We compute the critical temperature for the chiral transition in the background of a magnetic field in the linear sigma model, including the quark contribution and the thermomagnetic effects induced on the coupling constants at one-loop level. We show that the critical temperature decreases as a function of the field strength. The effect of fermions on the critical temperature is small and the main effect on this observable comes from the charged pions. The findings support the idea that the inverse magnetic catalysis phenomenon receives a contribution due only to chiral symmetry effects independent of the deconfinement transition.

We compute the decay width of $h^0\to c\overline{c}$ in the minimal supersymmetric Standard Model with quark flavor violation (QFV) at full one-loop level adopting the $\overline{\mathrm{DR}}$ renormalization scheme. We study the effects of $\tilde{c}-\tilde{t}$ mixing, taking into account the constraints from the B meson data. We show that the full one-loop corrected decay width $\mathrm{\Gamma }(h^0\to c\overline{c})$ is very sensitive to the minimal supersymmetric Standard Model QFV parameters. In a scenario with large ${\tilde{c}}_{L,R}-{\tilde{t}}_{L,R}$ mixing $\mathrm{\Gamma }(h^0\to c\overline{c})$ can differ up to $\sim \pm 35\%$ from its Standard Model value. After estimating the uncertainties of the width, we conclude that an observation of these supersymmetry QFV effects is possible at an $e^{+}{e}^{-}$ collider (International Linear Collider).

We calculate the electric dipole moment for the electron and neutron in the framework of the 3-3-1 model with heavy charged leptons. We assume that the only source of $CP$ violation arises from a complex trilinear coupling constant and the three complex vacuum expectation values. However, two of the vacua phases are absorbed and the other two are equal up to a minus sign. Hence only one physical phase survives. In order to be compatible with the experimental data this phase has to be smaller than $10^{-6}$.

A large class of two- and three-Higgs-doublet models with discrete symmetries has been employed in the literature to address various aspects of flavor physics. We analyze how the precision measurement of the Higgs to diphoton signal strength would severely constrain these scenarios due to the nondecoupling behavior of the charged scalars, to the extent that in the presence of exact discrete symmetry, the number of additional noninert scalar doublets can be constrained no matter how heavy the nonstandard scalars are. We demonstrate that if the scalar potential is endowed with appropriate global continuous symmetries together with soft breaking parameters, decoupling can be achieved thanks to the unitarity constraints on the mass-square differences of the heavy scalars.

In the standard model the rate of the ${\pi }^0$, $\eta$, ${\eta }^{\prime }$, $K_S$, $K_L\to \nu \overline{\nu }$ decays is predicted to be extremely small. Therefore, an observation of any of these mesons ($M^0$) decaying into an invisible final state would unambiguously signal the presence of new physics. The Bell-Steinberger relation connects $CP$ and $CPT$ violation in the mass matrix to $CP$ and $CPT$ violation in all decay channels of neutral kaons. It is a powerful tool for testing $CPT$ invariance in the $K^0-{\overline{K}}^0$ system, assuming that there are no significant undiscovered decay modes of either $K_S$ or $K_L$ which could contribute to the precision of the results. The $K_S,K_L\to \text{invisible}$ decays have never been tested and the question of how much these decays can influence the Bell-Steinberger analysis of the $K^0-{\overline{K}}^0$ system still remains open. In the present work, we propose a new experiment to search for the $M^0\to \text{invisible}$ decays which aims at probing new physics and answering this question. The experiment utilizes high-energy hadronic beams from the CERN SPS and the charge-exchange reactions of pions or kaons on nucleons of an active target, e.g., ${\pi }^{-}(K^{-})+p\to M^0+n$, as a source of the well-tagged $M^0$s emitted in the forward direction with the beam energy. If the decay $M^0\to \text{invisible}$ exists, it could be observed by looking for an excess of events with a specific signature: the complete disappearance of the beam energy in the detector. This unique signal of $M^0\to \text{invisible}$ decays allows for searches of the decays $K_S,K_L\to \text{invisible}$ with a sensitivity in the branching ratio $\mathrm{Br}(K_S(K_L)\to \text{invisible})\lesssim 10^{-8}(10^{-6})$, and ${\pi }^0,\eta ,{\eta }^{\prime }\to \text{invisible}$ decays with a sensitivity a few orders of magnitude beyond the present experimental limits. This experiment is complementary to the one recently proposed for the search for invisible decays of dark photons and fits well with the present kaon physics program at CERN.

We study the rare $B$ meson decays $B^{\pm ,0}\to J/\psi K^{+}{K}^{-}{K}^{\pm ,0}$, $B^{\pm ,0}\to J/\psi \varphi K^{\pm ,0}$, and search for $B^0\to J/\psi \varphi$, using $469\times {10}^6$ $B\overline{B}$ events collected at the $\mathrm{\Upsilon }(4S)$ resonance with the BABAR detector at the PEP-II $e^{+}{e}^{-}$ asymmetric energy collider. We present new measurements of branching fractions and a study of the $J/\psi \varphi$ mass distribution in search of new charmonium-like states. In addition, we search for the decay $B^0\to J/\psi \varphi$ and find no evidence of a signal.

The $p_{\mathrm{T}}$-differential production cross section of electrons from semileptonic decays of heavy-flavor hadrons has been measured at midrapidity in proton-proton collisions at $\sqrt{s}=2.76\mathrm{TeV}$ in the transverse momentum range $0.5<p_{\mathrm{T}}<12\mathrm{GeV}/c$ with the ALICE detector at the LHC. The analysis was performed using minimum bias events and events triggered by the electromagnetic calorimeter. Predictions from perturbative QCD calculations agree with the data within the theoretical and experimental uncertainties.