As in the case of Einstein or Lovelock gravity, the action of quartic quasitopological gravity has not a well-defined variational principle. In this paper, we first introduce a surface term which makes the variation of quartic quasitopological gravity well-defined. Second, we present the static charged solutions of quartic quasitopological gravity in the presence of a nonlinear electromagnetic field. One of the branches of these solutions presents a black brane with one or two horizons or a naked singularity depending on the charge and mass of the solution. The thermodynamics of these black branes are investigated through the use of the Gibbs free energy. In order to do this, we calculate the finite action by use of the counterterm method inspired by AdS/CFT correspondence. Introducing a Smarr-type formula, we also show that the conserved and thermodynamics quantities of these solutions satisfy the first law of thermodynamics. Finally, we present the charged rotating black branes in $n+1$ dimensions with $k\le [n/2]$ rotation parameters and investigate their thermodynamics.

After some introductory discussion of the definition of Finsler spacetimes and their symmetries, we consider a class of spherically symmetric and static Finsler spacetimes which are small perturbations of the Schwarzschild spacetime. The deviations from the Schwarzschild spacetime are encoded in three perturbation functions ${\varphi }_0(r)$, ${\varphi }_1(r)$ and ${\varphi }_2(r)$ which have the following interpretations: ${\varphi }_0$ perturbs the time function, ${\varphi }_1$ perturbs the radial length measurement and ${\varphi }_2$ introduces a spatial anisotropy which is a genuine Finsler feature. We work out the equations of motion for freely falling particles and for light rays, i.e., the timelike and lightlike geodesics, in this class of spacetimes, and we discuss the bounds placed on the perturbation functions by observations in the Solar system.

In this paper, we study the effects of an interaction between dark matter and dark energy through a two-scalar-field model with a potential $V(\varphi ,\chi )=e^{-\lambda \varphi }P(\varphi ,\chi )$, where $P(\varphi ,\chi )$ is a polynomial. We show that the cosmic expansion dynamics of the Universe is reproduced for a large range of the bare mass of the dark matter field and that there exist solutions with transient accelerated expansion. A modification in the exponential behavior of the potential is studied, with important physical implications, including the possibility of more realistic transient acceleration solutions.

In this work we extend the first order formalism for cosmological models that present an interaction between a fermionic and a scalar field. Cosmological exact solutions describing universes filled with interacting dark energy and dark matter have been obtained. Viable cosmological solutions with an early period of decelerated expansion followed by late acceleration have been found, notably one which presents a dark matter component dominating in the past and a dark energy component dominating in the future. In another one, the dark energy alone is the responsible for both periods, similar to a Chaplygin gas case. Exclusively accelerating solutions have also been obtained.

Many models of dark matter contain more than one new particle beyond those in the Standard Model. Often, heavier particles decay into the lightest dark matter particle as the Universe evolves. Here, we explore the possibilities which arise if one of the products in a $(\mathrm{\text{heavy particle}})\to (\mathrm{\text{dark matter}})$ decay is a positron, and the lifetime is shorter than the age of the Universe. The positrons cool down by scattering off the cosmic microwave background and eventually annihilate when they fall into Galactic potential wells. The resulting 511 keV flux not only places constraints on this class of models, but might even be consistent with that observed by the INTEGRAL satellite.

We develop a new test of local bias, by constructing a locally biased halo density field from sampling the dark matter-halo distribution. Our test differs from conventional tests in that it preserves the full scatter in the bias relation and it does not rely on perturbation theory. We put forward that bias parameters obtained using a smoothing scale $R$ can only be applied to computing the halo power spectrum at scales $k\sim 1/R$. Our calculations can automatically include the running of bias parameters and give vanishingly small loop corrections at low-$k$. Our proposal results in much better agreement of the sampling and perturbation theory results with simulations. In particular, unlike the standard interpretation of local bias in the literature, our treatment of local bias does not generate a constant power in the low-$k$ limit. We search for extra noise in the Poisson corrected halo power spectrum at wave numbers below its turnover and find no evidence of significant positive noise (as predicted by the standard interpretation) while we find evidence of negative noise coming from halo exclusion for very massive halos. Using perturbation theory and our nonperturbative sampling technique we also demonstrate that nonlocal bias effects discovered recently in simulations impact the power spectrum only at the few percent level in the weakly nonlinear regime.

We report the first case study of the phase diagram of $2+1$ flavor strongly interacting matter in $\beta$ equilibrium, using the Polyakov-Nambu-Jona-Lasinio model. Physical characteristics of relevant thermodynamic observables have been discussed. A comparative analysis with the corresponding observables in the Nambu-Jona-Lasinio model is presented. We find distinct differences between the models in terms of a number of thermodynamic quantities like the speed of sound, specific heat, various number densities, as well as entropy. The present study is expected to give us a better insight into the role that the superdense matter created in heavy-ion collision experiments plays in our understanding of the properties of matter inside the core of supermassive stars in the Universe.

We studied allowed region on the intergenerational mixing parameters of sleptons from a viewpoint of big-bang nucleosynthesis in a slepton-neutralino coannihilation scenario. In this scenario, ${}^7\mathrm{Li}$ and ${}^6\mathrm{Li}$ problems can be solved by considering exotic reactions caused by bound-state effects with a long-lived slepton. Light element abundances are calculated as functions of the relic density and lifetime of the slepton which considerably depend on the intergenerational mixing parameters. Compared with observational light element abundances, we obtain allowed regions on the intergenerational mixing. Ratio of selectron component to stau component, $c_e$, is allowed in $2\times {10}^{-11}\lesssim c_e\lesssim 2\times {10}^{-9}$ with solving both the ${}^7\mathrm{Li}$ and ${}^6\mathrm{Li}$ problems. Similarly, the ratio for smuon, $c_{\mu }$, is allowed in $c_{\mu }\lesssim 5\times {10}^{-5}$ for mass difference between slepton and neutralino, which is smaller than muon mass, and $c_{\mu }\lesssim 2\times {10}^{-10}$ for the mass difference in range between muon mass and 125 MeV. We also discuss collider signatures of the slepton decays. We find characteristic double peaks in momentum distribution of event number of the slepton decays with allowed mixing parameters. Discoveries of the double peaks at future collider experiments should confirm our scenario.

We demonstrate enhanced di-Higgs production at the LHC in the presence of modifications of the effective couplings of Higgs to gluons from new, light, colored scalars. While our results apply to an arbitrary set of colored scalars, we illustrate the effects with a real color octet scalar—a simple, experimentally viable model involving a light ($\simeq 125–300\mathrm{GeV}$) colored scalar. Given the recent LHC results, we consider two distinct scenarios: First, if the Higgs is indeed near 125 GeV, we show that the di-Higgs cross section could be up to nearly ${10}^3$ times the Standard Model rate for particular octet couplings and masses. This is potentially observable in single Higgs production modes, such as $pp\to hh\to \gamma \gamma b\overline{b}$ as well as $pp\to hh\to {\tau }^{+}{\tau }^{-}b\overline{b}$ where a small fraction of the $\gamma \gamma$ or ${\tau }^{+}{\tau }^{-}$ events near the putative Higgs invariant mass peak contain also a $b\overline{b}$ resonance consistent with the Higgs mass. Second, if the Higgs is not at 125 GeV (and what the LHC has observed is an impostor), we show that the same parameter region where singly-produced Higgs production can be suppressed below current LHC limits, for a heavier Higgs mass, also simultaneously predicts substantially enhanced di-Higgs production. We point out several characteristic signals of di-Higgs production with a heavier Higgs boson, such as $pp\to hh\to W^{+}{W}^{-}{W}^{+}{W}^{-}$, which could use same-sign dileptons or trileptons plus missing energy to uncover evidence.

In this work, we study the exclusive channel of flavor changing neutral current transition, i.e., $B\to K^{*}{\ell }^{+}{\ell }^{-}$ in the framework of a family of nonuniversal $Z^{\prime }$ model. In this model, the $Z^{\prime }$ boson couplings to the fermions could lead to flavor changing neutral current transition (in standard model, this transition is forbidden at tree level and occur via loop) at tree level. In addition, the off-diagonal elements of these effective chiral $Z^{\prime }$ couplings can contain new weak phases that provide a new source of $CP$ violation and, therefore, could explain the $CP$ asymmetries in the current high energy colliders. In this context, we have studied the polarized and unpolarized $CP$ violation asymmetries for said decay. These asymmetries are highly suppressed in the standard model but significantly enhanced in $Z^{\prime }$ model. In addition to the $CP$ violation asymmetries, the single lepton polarization asymmetries are also studied and found to be sensitive to the couplings of the $Z^{\prime }$ boson. Finally, it is analyzed that all of these asymmetries, which will hopefully be tested at LHC, can serve to probe nonuniversal $Z^{\prime }$ model; particularly, the accurate measurements of these asymmetries may play a crucial role in extracting the precise values of the coupling parameters of the $Z^{\prime }$ boson.

A proposal by Lüscher enables one to compute the scattering phases of elastic two-body systems from the energy levels of the lattice Hamiltonian in a finite volume. In this work, we generalize the formalism to $S$-, $P$- and $D$-wave meson and baryon resonances, and general total momenta. Employing nonvanishing momenta has several advantages, among them making a wider range of energy levels accessible on a single lattice volume and shifting the level crossing to smaller values of $m_{\pi }L$.

In this paper, a study of light-cone distribution amplitudes for $p$-wave heavy mesons is presented in both general and heavy quark frameworks. Within the light-front approach, the leading twist light-cone distribution amplitudes, ${\varphi }_M(u)$ and their relevant decay constants of heavy scalar, axial-vector, and tensor mesons, $f_M$, are formulated. The relations of some decay constants can be simplified when the heavy quark limit is taken into account. After fixing the parameters which appear in a Gaussian wave function, the corresponding decay constants are calculated and compared with those of other theoretical approaches. The curves and the first six $\xi$ moments of ${\varphi }_M(u)$ are plotted and estimated. These results all endorse the requirements of heavy quark symmetry.

Jet charge has played an important role in experimentally testing the parton model and the Standard Model, and has many potential LHC applications. The energy-weighted charge of a jet is not an infrared-safe quantity, so hadronization must be taken into account. Here we develop the formalism to calculate it, cleanly separating the nonperturbative from the perturbative physics, which we compute at one-loop order. We first study the average and width of the jet charge distribution, for which the nonperturbative input is related to (dihadron) fragmentation functions. In an alternative and novel approach, we consider the full nonperturbative jet charge distribution and calculate its evolution and jet algorithm corrections, which have a natural Monte Carlo-style implementation. Our numerical results are compared to pythia and show reasonable agreement. This calculation can directly be extended to similar track-based observables, such as the total track momentum generated by an energetic parton.

Top taggers which identify and reconstruct boosted top quarks have been established as novel tools for a multitude of LHC analyses. We show how single top production in association with a light-flavor or bottom jet can be observed in the boosted phase space regime. The full top reconstruction as part of the tagging algorithm allows us to define a distinctive kinematic angle which clearly separates different single top production processes.

We study the exclusive nonleptonic two-body $B_c$ decays within factorization approximation, in the framework of the relativistic independent quark model based on a confining potential in the scalar-vector harmonic form. The relevant weak form factors and branching ratios for different decay modes $(B_c\to PP,PV,VP)$ are predicted in reasonable agreement with other quark model predictions. We find that the dominant contribution to the $B_c$-meson lifetime comes from the Cabibbo-Kobayashi-Masakawa favored $\overline{c}\to \overline{s}$, $\overline{d}$ decay modes, and the most promising modes are found to be $B_c^{-}\to {\overline{B}}_s^0{\pi }^{-}$, $B_c^{-}\to {\overline{B}}_s^0{\rho }^{-}$ and $B_c^{-}\to {\overline{B}}_s^{\star 0}{\pi }^{-}$ with predicted branching ratios of 12.01, 9.96, and 8.61%, respectively, which might be easily detected at the hadron collider in the near future.

Using a covariant spectator quark model that describes the recent lattice QCD data for the $\Delta$ electromagnetic form factors and all available experimental data on $\gamma N\to \Delta$ transitions, we analyze the charge and magnetic dipole distributions of the $\Delta$ baryon and discuss its shape. We conclude that the quadrupole moment of the $\Delta$ is a good indicator of the deformation and that the ${\Delta }^{+}$ charge distribution has an oblate shape. We also calculate transverse moments and find that they do not lead to unambiguous conclusions about the underlying shape.

Stimulated by the recent attention given to the texture zeros found in the quark mass matrices sector of the standard model, an analytical method for identifying (or excluding) texture zeros models will be implemented here. Starting from arbitrary quark mass matrices and making a suitable weak basis transformation, we are be able to find an equivalent quark mass matrix. It is shown that the number of nonequivalent quark mass matrix representations is finite. We give exact numerical results for parallel and nonparallel four-texture zeros models. We find that some five-texture zeros Ansätze are in agreement with all present experimental data, and we confirm definitively that six-texture zeros of Hermitian quark mass matrices are not viable models anymore.

High energy astrophysical neutrinos carry relevant information about the origin and propagation of cosmic rays. They can be created as a by-product of the interactions of cosmic rays in the sources and during propagation of these high energy particles through the intergalactic medium. The determination of flavor composition in this high energy flux is important because it presents a unique chance to probe our understanding of neutrino flavor oscillations at gamma factors $>{10}^{21}$. In this work we develop a new statistical technique to study the flavor composition of the incident neutrino flux, which is based on the multipeak structure of the longitudinal profiles of very deep electron and tau neutrino horizontal air showers. Although these longitudinal profiles can be observed by means of fluorescence telescopes placed over the Earth’s surface, orbital detectors are more suitable for neutrino observations owing to their much larger aperture. Therefore, we focus on the high energy region of the neutrino spectrum relevant for observations with orbital detectors like the planned JEM-EUSO telescope.

The process $\psi (3686)\to {\pi }^0{h}_c$, $h_c\to \gamma {\eta }_c$ has been studied with a data sample of $106\pm 4$ million $\psi (3686)$ events collected with the BESIII detector at the BEPCII storage ring. The mass and width of the $P$-wave charmonium spin-singlet state $h_c({}^{1}P_1)$ are determined by simultaneously fitting distributions of the ${\pi }^0$ recoil mass for 16 exclusive ${\eta }_c$ decay modes. The results, $M(h_c)=3525.31\pm 0.11(\mathrm{stat})\pm 0.14(\mathrm{syst})\mathrm{MeV}/c^2$ and $\Gamma (h_c)=0.70\pm 0.28\pm 0.22\mathrm{MeV}$, are consistent with and more precise than previous measurements. We also determine the branching ratios for the 16 exclusive ${\eta }_c$ decay modes, five of which have not been measured previously. New measurements of the ${\eta }_c$ line-shape parameters in the $E1$ transition $h_c\to \gamma {\eta }_c$ are made by selecting candidates in the $h_c$ signal sample and simultaneously fitting the hadronic mass spectra for the 16 ${\eta }_c$ decay channels. The resulting ${\eta }_c$ mass and width values are $M({\eta }_c)=2984.49\pm 1.16\pm 0.52\mathrm{MeV}/c^2$ and $\Gamma ({\eta }_c)=36.4\pm 3.2\pm 1.7\mathrm{MeV}$.

We present a precision study of the ${\psi }^{\prime }\to {\pi }^{0}J/\psi$ and $\eta J/\psi$ decay modes. The measurements are obtained using $106\times {10}^6$ ${\psi }^{\prime }$ events accumulated with the BESIII detector at the BEPCII $e^{+}{e}^{-}$ collider operating at a center-of-mass energy corresponding to the ${\psi }^{\prime }$ mass. We obtain $\mathcal{B}({\psi }^{\prime }\to {\pi }^{0}J/\psi )=(1.26\pm 0.02(\mathrm{stat})\pm 0.03(\mathrm{syst}))\times {10}^{-3}$ and $\mathcal{B}({\psi }^{\prime }\to \eta J/\psi )=(33.75\pm 0.17(\mathrm{stat})\pm 0.86(\mathrm{syst}))\times {10}^{-3}$. The branching fraction ratio $R=\frac{\mathcal{B}({\psi }^{\prime }\to {\pi }^{0}J/\psi )}{\mathcal{B}({\psi }^{\prime }\to \eta J/\psi )}$ is determined to be $(3.74\pm 0.06(\mathrm{stat})\pm 0.04(\mathrm{syst}))\times {10}^{-2}$. The precision of these measurements of $\mathcal{B}({\psi }^{\prime }\to {\pi }^{0}J/\psi )$ and $R$ represent a significant improvement over previously published values.