In this paper, we will analyze three-dimensional supersymmetric Yang-Mills theory coupled to matter fields in $SIM(1)$ superspace formalism. The original theory which is invariant under the full Lorentz group has $\mathcal{N}=1$ supersymmetry. However, when we break the Lorentz symmetry down to $SIM(1)$ group, the $SIM(1)$ superspace will break half the supersymmetry of the original theory. Thus, the resultant theory in $SIM(1)$ superspace will have $\mathcal{N}=1/2$ supersymmetry. This is the first time that $\mathcal{N}=1$ supersymmetry will be broken down to $\mathcal{N}=1/2$ supersymmetry, for a three-dimensional theory, on a manifold without a boundary. This is because it is not possible to use nonanticommutativity to break $\mathcal{N}=1$ supersymmetry down to $\mathcal{N}=1/2$ supersymmetry in three dimensions.

We construct and study the approximate stress-energy tensor of the quantized massive scalar field in higher dimensional Schwarzschild-Tangherlini spacetimes. The stress-energy tensor is calculated within the framework of the Schwinger-DeWitt approach. It is shown that in $N$-dimensional spacetime the main approximation can be obtained from the effective action constructed form the coincidence limit of the Hadamard-DeWitt coefficient $a_k$, where $k-1$ is the integer part of $N/2$. The backreaction of the quantized field upon the black hole spacetime is analyzed and the quantum-corrected Komar mass and the Hawking temperature is calculated. It is shown that for the minimal and conformal coupling the increase of the Komar mass of the quantum corrected black hole leads to the decrease of its Hawking temperature. This is not generally true for more exotic values of the coupling parameter. The general formula describing the vacuum polarization, $⟨{\varphi }^2⟩$, is constructed and briefly examined.

In this paper, we address the issue of black hole solutions in ($1+1$)-dimensional nonprojectable Horava-Lifshitz gravity. We consider several models by considering different potentials in the scalar matter sector. We also consider the gravitational collapse of a distribution of pressureless dust filling a region in one-dimensional space. The time of the collapse can be faster or slower depending on the parameter $\lambda$ of the theory.

The resonant mode spectrum of the Kerr-Newman spacetime is presently unknown. These modes, called the quasinormal modes, play a central role in determining the stability of Kerr-Newman black holes and their response to perturbations. We present a new formalism, generalized from time-independent perturbation theory in quantum mechanics, for calculating the quasinormal mode frequencies of weakly charged Kerr-Newman spacetimes of arbitrary spin. Our method makes use of an original technique for applying perturbation theory to zeroth-order solutions that are not square-integrable, and it can be applied to other problems in theoretical physics. The new formalism reveals no unstable modes, which together with previous results in the slow-rotation limit strongly indicates the modal stability of the Kerr-Newman spacetime. Our techniques and results are of interest in the areas of holographic duality, foundational problems in general relativity, and possibly in astrophysical systems.

We study several classical-like properties of $q$-deformed nonlinear coherent states as well as nonclassical behaviors of $q$-deformed version of the Schrödinger cat states in noncommutative space. Coherent states in $q$-deformed space are found to be minimum uncertainty states together with the squeezed photon distributions unlike the ordinary systems, where the photon distributions are always Poissonian. Several advantages of utilizing cat states in noncommutative space over the standard quantum mechanical spaces have been reported here. For instance, the $q$-deformed parameter has been utilized to improve the squeezing of the quadrature beyond the ordinary case. Most importantly, the parameter provides an extra degree of freedom by which we achieve both quadrature squeezed and number squeezed cat states at the same time in a single system, which is impossible to achieve from ordinary cat states.

We investigate the cosmological dynamics in teleparallel gravity with nonminimal coupling. We analytically extract several asymptotic solutions, and we numerically study the exact phase-space behavior. Comparing the obtained results with the corresponding behavior of nonminimal scalar-curvature theory, we find significant differences, such as the rare stability and the frequent presence of oscillatory behavior.

In the framework of loop quantum gravity, we define a new Hilbert space of states which are solutions of a large number of components of the diffeomorphism constraint. On this Hilbert space, using the methods of Thiemann, we obtain a family of gravitational scalar constraints. They preserve the Hilbert space for every choice of lapse function. Thus adjointness and commutator properties of the constraint can be investigated in a straightforward manner. We show how the space of solutions of the symmetrized constraint can be defined by spectral decomposition, and the Hilbert space of physical states by subsequently fully implementing the diffeomorphism constraint. The relationship of the solutions to those resulting from a proposal for a symmetric constraint operator by Thiemann remains to be elucidated.

We investigate the viable exponential $f(R)$ gravity in the metric formalism with $f(R)=-\beta R_s(1-e^{-R/R_s})$. The latest sample of the Hubble parameter measurements with 23 data points is used to place bounds on this $f(R)$ model. A joint analysis is also performed with the luminosity distances of type Ia supernovae and baryon acoustic oscillations in the clustering of galaxies, and the shift parameters from the cosmic microwave background measurements, which leads to $0.240<{\mathrm{\Omega }}_m^0<0.296$ and $\beta >1.47$ at the $1\sigma$ confidence level. The evolutions of the deceleration parameter $q(z)$ and the effective equations of state ${\omega }_{\mathrm{de}}^{\text{eff}}(z)$ and ${\omega }_{\text{tot}}^{\text{eff}}(z)$ are displayed. By taking the best-fit parameters as prior values, we work out the transition redshift (deceleration/acceleration) $z_T$ to be about 0.77. It turns out that the recent observations are still unable to distinguish the background dynamics in the $\mathrm{\Lambda }\mathrm{CDM}$ and exponential $f(R)$ models.

We study self-interacting dark matter coupled to the Standard Model via the Higgs portal. We consider a scenario where dark matter is a thermal relic with strong enough self-interactions that can alleviate the problems of collisionless dark matter. We study constraints from direct-detection searches, the LHC, and big bang nucleosynthesis. We show that the tension between these constraints and the need for sufficiently strong self-interactions with light mediators can be alleviated by coupling the mediator to either active or sterile neutrinos. Future direct-detection data offers great potential and can be used to find evidence of a light mediator and verify that dark matter scatters via long-range self-interactions.

Systems of interacting networks of strings such as cosmic strings or quantum vortices can be approximated in a certain regime as an anisotropic fluid with an equation of state depending on a conserved flux. The equations for ideal magnetohydrodynamics are shown to be another example of a fluid of this type. Previous work on these fluids is now extended to include dissipative effects. The new dissipative terms are discussed in terms of both standard resistive magnetohydrodynamics and small-scale structure formation in networks of cosmic strings. The requirement of frame invariance is shown to restrict the form of higher order corrections to heat flow in the anisotropic direction.

In the standard asymptotic expansion of four-dimensional static asymptotically flat spacetimes, the coefficient of the first subleading term of the lapse function can be identified with the mass of the spacetime. Using the Hamiltonian formalism we show that, in asymptotically locally anti–de Sitter spacetimes endowed with a scalar field, the mass can read off in the same way only when the boundary conditions are compatible with the asymptotic realization of the anti–de Sitter symmetry. Since the mass is determined only by the spatial metric and the scalar field, the above effect appears by considering not only the constraints, but also the dynamic field equations, which relate the spatial metric with the lapse function. In particular, this result implies that some prescriptions for computing the mass of a hairy spacetime are not suitable when the scalar field breaks the asymptotic anti–de Sitter invariance.

We have investigated real graviton emission in the Arkani-Hamed-Dimopoulos–Dvali (ADD) and Randall-Sundrum (RS) models of extra dimensions through the photoproduction process $pp\to p\gamma p\to pGqX$ at the LHC. We have considered all contributions from the subprocesses $\gamma q\to Gq$, where $q=u,d,c,s,b,\overline{u},\overline{d},\overline{c},\overline{s},\overline{b}$ quark. The constraints on model parameters of the ADD and RS models of extra dimensions have been calculated. During numerical calculations we have taken into account 3, 4, 5, and 6 large extradimensional scenarios. The constraints on RS model parameters have been calculated by considering $G\to \gamma \gamma$, $e\overline{e}$, $\mu \overline{\mu }$ decay channels of the graviton.

In the next-to-minimal supersymmetric standard model (NMSSM), a sizable coupling $\lambda$ between the singlet and Higgs fields can naturally accommodate the observed Higgs boson mass of 125 GeV. This large coupling also results in a large separation between the Higgsino and singlino mass scales in the neutralino sector to evade stringent constraints from direct detection experiments. Most of the natural parameter space in this setup therefore contains light Higgsinos that can decay into the singlino and the 125 GeV Higgs. If the Higgsinos are to be light enough to be produced at the LHC, the mass gap $m_{{\tilde{\chi }}_2^0}-(m_{{\tilde{\chi }}_1^0}+m_h)$ is generally fairly low, resulting in small missing energy. We study the collider phenomenology of this process and demonstrate that the $4b+j+{\cancel{E}}_{\mathrm{T}}$ signal arising from $pp\to {\tilde{\chi }}_i^0{\tilde{\chi }}_j^{0}jj$ process can be a viable channel to search for this low mass gap region at the 14 TeV LHC. In addition, we find that a potential signal from the LHC search, in tandem with direct detection experiments, can distinguish the NMSSM from the analogous process in the minimal supersymmetric standard model, where the bino plays the role of the singlino, for positive values of the $\mu$ parameter even when the additional singlet-dominated (pseudo)scalars are absent or indistinguishable from the Higgs in the decay.

We study the enhancement of the di-Higgs production cross section resulting from the resonant decay of a heavy Higgs boson at hadron colliders in a model with a Higgs singlet. This enhancement of the double Higgs production rate is crucial in understanding the structure of the scalar potential and we determine the maximum allowed enhancement such that the electroweak minimum is a global minimum. The di-Higgs production enhancement can be as large as a factor of $\sim 18(13)$ for the mass of the heavy Higgs around 270(420) GeV relative to the Standard Model rate at 14 TeV for parameters corresponding to a global electroweak minimum.

In a dynamical lattice simulation with the overlap Dirac operator and $N_f=2$ mass degenerate quarks we study all possible $J=0$ and $J=1$ correlators upon exclusion of the low-lying “quasizero” modes from the valence quark propagators. After subtraction of a small amount of such Dirac eigenmodes all disconnected contributions vanish and all possible point-to-point $J=0$ correlators with different quantum numbers become identical, signaling a restoration of the $SU(2{)}_L\times SU(2{)}_R\times U(1{)}_A$. The original ground state of the $\pi$ meson does not survive this truncation, however. In contrast, in the $I=0$ and $I=1$ channels for the $J=1$ correlators the ground states have a very clean exponential decay. All possible chiral multiplets for the $J=1$ mesons become degenerate, indicating a restoration of an $SU(4)$ symmetry of the dynamical QCD-like string.

We present the full $\mathcal{O}({\alpha }_s)$ supersymmetric QCD corrections for stop-antistop annihilation into electroweak final states within the Minimal Supersymmetric Standard Model. We also incorporate Coulomb corrections due to gluon exchange between the incoming stops. Numerical results for the annihilation cross sections and the predicted neutralino relic density are presented. We show that the impact of the radiative corrections on the cosmologically preferred region of the parameter space can become larger than the current experimental uncertainty, shifting the relic bands within the considered regions of the parameter space by up to a few tens of GeV.

We present an attempt to explicitly estimate the effect of soft gluon radiation in the nonrelativistic QCD scheme. We stress that the energy of the emitted final state gluons is bounded from below by the confinement scale, and this leads to non-negligible changes in the final state kinematics.

We attempt an extraction of the pretzelosity distribution ($h_{1T}^{\perp }$) from preliminary COMPASS, HERMES, and JLAB experimental data on $\sin (3{\varphi }_h-{\varphi }_S)$ asymmetry on proton, and effective deuteron and neutron targets. The resulting distributions, albeit with big errors, for the first time show tendency for up-quark pretzelosity to be positive and down-quark pretzelosity to be negative. A model relation of pretzelosity distribution and orbital angular momentum of quarks is used to estimate contributions of up and down quarks.

The strategy of constraining the lepton flavor mixing from remnant $CP$ symmetry is investigated in a rather general way. The neutrino mass matrix generally admits four remnant $CP$ transformations which can be derived from the measured lepton mixing matrix in the charged lepton diagonal basis. Conversely, the lepton mixing matrix can be reconstructed from the postulated remnant $CP$ transformations. All mixing angles and $CP$-violating phases can be completely determined by the full set of remnant $CP$ transformations or three of them. When one or two remnant $CP$ transformations are preserved, the resulting lepton mixing matrix would depend on three real parameters or one real parameter, respectively, in addition to the parameters characterizing the remnant $CP$. The concrete form of the mixing matrix is also presented. The phenomenological predictions for the mixing parameters are discussed. The conditions leading to vanishing or maximal Dirac $CP$ violation are studied.

In the past few years, the so-called Chen et al. approach of the nucleon spin decomposition has been widely discussed and elaborated on. In this article we propose a genuine differential geometric understanding of this approach. We mainly highlight its relation to the “dressing field method” we advocated in Fournel et al. [Int. J. Geom. Methods Mod. Phys. 11, 1450016 (2014)]. The gauge invariance of the Chen et al. decomposition is discussed.