In this paper we compute models for relativistic white dwarfs in the presence of strong magnetic fields. These models possibly contribute to superluminous SNIa. With an assumed axisymmetric and poloidal magnetic field, we study the possibility of the existence of super-Chandrasekhar magnetized white dwarfs by solving numerically the Einstein-Maxwell equations, by means of a pseudospectral method. We obtain a self-consistent rotating and nonrotating magnetized white dwarf model. According to our results, a maximum mass for a static magnetized white dwarf is $2.13{\mathrm{M}}_{\odot }$ in the Newtonian case, and $2.09{\mathrm{M}}_{\odot }$ when taking into account general relativistic effects. Furthermore, we present results for rotating magnetized white dwarfs. The maximum magnetic field strength reached at the center of white dwarfs is of the order of ${10}^{15}\mathrm{G}$ in the static case, whereas for magnetized white dwarfs, rotating with the Keplerian angular velocity, it is of the order of ${10}^{14}\mathrm{G}$.

The correlation function of the $0^{-+}$ pseudoscalar glueball current is calculated based on the semiclassical expansion for quantum chromodynamics (QCD) in the instanton liquid background. Besides taking the pure classical contribution from instantons and the perturbative one into account, we calculate the contribution arising from the interaction (or the interference) between instantons and the quantum gluon fields, which is infrared free and more important than the pure perturbative one. Instead of the usual zero-width approximation for the resonances, the Breit-Wigner form with a correct threshold behavior for the spectral function of the finite-width resonance is adopted. The properties of the $0^{-+}$ pseudoscalar glueball are investigated via a family of the QCD Laplacian sum rules. A consistency between the subtracted and unsubtracted sum rules is very well justified. The values of the mass, decay width, and coupling constants for the $0^{-+}$ resonance in which the glueball fraction is dominant are obtained.

We present a gauge-invariant effective action for the Abelian-Higgs model (scalar electrodynamics) with a chemical potential $\mu$ on a ($1+1$)-dimensional lattice. This formulation provides an expansion in the hopping parameter $\kappa$ which we test with Monte Carlo simulations for a broad range of the inverse gauge coupling ${\beta }_{pl}=1/g^2$ and small values of the scalar self-coupling $\lambda$. In the opposite limit of infinitely large $\lambda$, the partition function can be written as a traced product of local tensors which allows us to write exact blocking formulas. Gauss’s law is automatically satisfied and the introduction of $\mu$ has consequences only if we have an external electric field, $g^2=0$ or an explicit gauge symmetry breaking. The time-continuum limit of the blocked transfer matrix can be obtained numerically and, for $g^2=0$ and a spin-1 truncation, the small volume energy spectrum is identical to the low energy spectrum of a two-species Bose-Hubbard model in the limit of large on-site repulsion. We extend this procedure for finite ${\beta }_{pl}$ and derive a spin-1 approximation of the Hamiltonian. It involves new terms corresponding to transitions among the two species in the Bose-Hubbard model. We propose an optical lattice implementation involving a ladder structure.

We present a minimal renormalizable nonsupersymmetric $SO(10)$ grand unified model with a symmetry breaking sector consisting of Higgs fields in the $54_H+126_H+10_H$ representations. This model admits a single intermediate scale associated with Pati-Salam symmetry along with a discrete parity. Spontaneous symmetry breaking, the unification of gauge couplings, and proton lifetime estimates are studied in detail in this framework. Including threshold corrections self-consistently obtained from a full analysis of the Higgs potential, we show that the model is compatible with the current experimental bound on proton lifetime. The model generally predicts an upper bound of few times ${10}^{35}\mathrm{yr}$ for proton lifetime, which is not too far from the present Super-Kamiokande limit of ${\tau }_p\gtrsim 1.29\times {10}^{34}\mathrm{yr}$. With the help of a Pecci-Quinn symmetry and the resulting axion, the model provides a suitable dark matter candidate while also solving the strong $CP$ problem. The intermediate scale, $M_I\approx ({10}^{13}–{10}^{14})\mathrm{GeV}$ which is also the $B-L$ scale, is of the right order for the right-handed neutrino mass which enables a successful description of light neutrino masses and oscillations. The Yukawa sector of the model consists of only two matrices in family space and leads to a predictive scenario for quark and lepton masses and mixings. The branching ratios for proton decay are calculable with the leading modes being $p\to e^{+}{\pi }^0$ and $p\to \overline{\nu }{\pi }^{+}$. Even though the model predicts no new physics within the reach of the LHC, the next-generation proton decay detectors and axion search experiments have the capability to reach a verdict on this minimal scenario.

For potentials with $n$-Higgs-boson doublets stability, electroweak-symmetry breaking and the stationarity equations are discussed in detail. This is done within the bilinear formalism which simplifies the investigation, in particular since irrelevant gauge degrees of freedom are systematically avoided. For the case that the potential leads to the physically relevant electroweak symmetry breaking, the mass matrices of the physical Higgs bosons are given explicitly.

We study the effect of gravitational focusing of the Earth on dark matter. We find that the effect can produce a detectable diurnal modulation in the dark matter signal for part of the parameter space which for high dark matter masses is larger than the diurnal modulation induced by the fluctuations in the flux of dark matter particles due to the rotation of the Earth around its own axis. The two sources of diurnal modulation have different phases and can be distinguished from each other. We demonstrate that the diurnal modulation can potentially check the self-consistency of experiments that observe annual modulated signals that can be attributed to dark matter. Failing to discover a daily varying signal can result conclusively in the falsification of the hypothesis that the annual modulation is due to dark matter. We also suggest that null result experiments should check for a daily modulation of their rejected background signal with specific phases. A potential discovery could mean that dark matter collisions have been vetoed out.

Considering the supersymmetric models with light neutralino and $R$-parity violation, we perform estimates of the signal rate expected at the recently proposed fixed target SHiP experiment exploiting the CERN SPS beam of 400 GeV protons. We extend the existing studies by introducing new production channels (in particular, through the beauty mesons) and decay modes. We also constrain the model parameter space from analysis of negative results of the CHARM experiment.

We calculate the amplitude of the rare flavor-changing neutral-current decay $B\to \pi {\ell }^{+}{\ell }^{-}$ at large recoil of the pion. The nonlocal contributions in which the weak effective operators are combined with the electromagnetic lepton-pair emission are systematically taken into account. These amplitudes are calculated at off-shell values of the lepton-pair mass squared, $q^2<0$, employing the operator-product expansion, QCD factorization and light-cone sum rules. The results are fitted to hadronic dispersion relations in $q^2$, including the intermediate vector meson contributions. The dispersion relations are then used in the physical region $q^2>0$. Our main result is the process-dependent addition $\mathrm{\Delta }{C}_9^{(B\pi )}(q^2)$ to the Wilson coefficient $C_9$ obtained at $4m_{\ell }^2<q^2\lesssim m_{J/\psi }^2$. Together with the $B\to \pi$ form factors from light-cone sum rules, this quantity is used to predict the differential rate, direct $CP$ asymmetry and isospin asymmetry in $B\to \pi {\ell }^{+}{\ell }^{-}$. We also estimate the total rate of the rare decay $B\to \pi \nu \overline{\nu }$.

We determine all spacetime flows which lead to a Hamiltonian dynamics in the space of general-relativistic initial data sets with asymptotically Kerr–de Sitter ends. The corresponding Hamiltonians are calculated. Some implications for black-hole thermodynamics are pointed out.

Linear stability of brane induced gravity in two codimensions on a static pure tension background is investigated. The brane is regularized as a ring of finite circumference in extra space. By explicitly calculating the vacuum persistence amplitude of the corresponding quantum theory, we show that the parameter space is divided into two regions—one corresponding to a stable Minkowski vacuum on the brane and one being plagued by ghost instabilities. This analytical result affirms a recent nonlinear, but mainly numerical analysis. The main result is that the ghost is absent for a sufficiently large brane tension, in perfect agreement with a value expected from a natural effective field theory point of view. Unfortunately, the linearly stable parameter regime is either ruled out phenomenologically or becomes unstable for nontrivial cosmologies. We argue that supercritical brane backgrounds constitute the remaining window of opportunity. In the special case of a tensionless brane, we find that the ghost exists for all phenomenologically relevant values of the induced gravity scale. Regarding this case, there are contradicting results in the literature, and we are able to fully resolve this controversy by explicitly uncovering the errors made in the “no-ghost” analysis. Finally, a Hamiltonian analysis generalizes the ghost result to more than two codimensions.

We study the geodesic motion of massive and massless test particles in the background of equally spinning Myers–Perry–anti-de Sitter (AdS) black holes in five dimensions. By adopting a coordinate system that makes manifest the cohomogeneity-1 property of these spacetimes, the equations of motion simplify considerably. This allows us to easily separate the radial motion from the angular part and to obtain solutions for angular trajectories in a compact closed form. For the radial motion, we focus our attention on spherical orbits. In particular, we determine the timelike innermost stable circular orbits (ISCOs) for these asymptotically AdS spacetimes, as well as the location of null circular orbits. We find that the ISCO dives below the ergosurface for black holes rotating close to extremality and merges with the event horizon exactly at extremality, in analogy with the four-dimensional Kerr case. For sufficiently massive black holes in AdS, there exists a spin parameter range in which the background spacetime is stable against super-radiance and the ISCO lies inside the ergoregion. Our results for massless geodesics show that there are no stable circular null orbits outside the horizon, but there exist such orbits inside the horizon, as well as around overextremal spacetimes, i.e., naked singularities. We also discuss how these orbits deform from the static to the rotating case.

We study metric transformations which depend on a scalar field $\varphi$ and its first derivatives and confirm that the number of physical degrees of freedom does not change under such transformations, as long as they are not singular. We perform a Hamiltonian analysis of a simple model in the gauge $\varphi =t$. In addition, we explicitly show that the transformation and the gauge fixing do commute in transforming the action. We then extend the analysis to more general gravitational theories and transformations in general gauges. We verify that the set of all constraints and the constraint algebra are left unchanged by such transformations and conclude that the number of degrees of freedom is not modified by a regular and invertible generic transformation among two metrics. We also discuss the implications for the recently called “hidden” constraints and for the case of a singular transformation, also known as mimetic gravity.

The measurements of the Higgs mass and top Yukawa coupling indicate that we live in a very special universe, at the edge of the absolute stability of the electroweak vacuum. If fully stable, the Standard Model (SM) can be extended all the way up to the inflationary scale and the Higgs field, nonminimally coupled to gravity with strength $\xi$, can be responsible for inflation. We show that the successful Higgs inflation scenario can also take place if the SM vacuum is not absolutely stable. This conclusion is based on two effects that were overlooked previously. The first one is associated with the effective renormalization of the SM couplings at the energy scale $M_P/\xi$, where $M_P$ is the Planck scale. The second one is a symmetry restoration after inflation due to high temperature effects that leads to the (temporary) disappearance of the vacuum at Planck values of the Higgs field.

We study the electroweak baryogenesis in the framework of the effective field theory. Our study shows that by introducing a light singlet scalar particle and a dimension-5 operator, it can provide the strong first order phase transition and the source of the $CP$-violation during the phase transition, and then produce abundant particle phenomenology at zero temperature. We also show the constraints on the new physics scale from the observed baryon-to-photon ratio, the low-energy experiments, and the LHC data.

We study the factorization of the dijet cross section in $e^{+}{e}^{-}$ annihilation using the generalized exclusive jet algorithm which includes the cone-type, the JADE, the $k_T$, the anti-$k_T$ and the Cambridge/Aachen jet algorithms as special cases. In order to probe the characteristics of the jet algorithms in a unified way, we consider the generalized $k_T$ jet algorithm with an arbitrary weight of the energies, in which various types of the $k_T$-type algorithms are included for specific values of the parameter. We show that the jet algorithm respects the factorization property for the parameter $\alpha <2$. The factorized jet function and the soft function are well defined and infrared safe for all the jet algorithms except the $k_T$ algorithm. The $k_T$ algorithm ($\alpha =2$) breaks the factorization since the jet and the soft functions are infrared divergent and are not defined for $\alpha =2$, though the dijet cross section is infrared finite. In the jet algorithms which enable factorization, we give a phenomenological analysis using the resummed and the fixed-order results.

We study the dynamical evolution of the so-called chiral magnetic effect in an electromagnetic conductor. To this end, we consider the coupled set of corresponding Maxwell and chiral anomaly equations, and we prove that these can be derived from chiral kinetic theory. After integrating the chiral anomaly equation over space in a closed volume, it leads to a quantum conservation law of the total helicity of the system. A change in the magnetic helicity density comes together with a modification of the chiral fermion density. We study in Fourier space the coupled set of anomalous equations, and we obtain the dynamical evolution of the magnetic fields, magnetic helicity density, and chiral fermion imbalance. Depending on the initial conditions, we observe how the helicity might be transferred from the fermions to the magnetic fields, or vice versa, and find that the rate of this transfer also depends on the scale of wavelengths of the gauge fields in consideration. We then focus our attention on the quark-gluon plasma phase and analyze the dynamical evolution of the chiral magnetic effect in a very simple toy model. We conclude that an existing chiral fermion imbalance in peripheral heavy ion collisions would affect the magnetic field dynamics and, consequently, the charge-dependent correlations measured in these experiments.

Experimental results indicate a possible relation between the lepton and quark mixing matrices of the form $U_{\mathrm{PMNS}}\approx V_{\mathrm{CKM}}^{†}{U}_X$, where $U_X$ is a matrix with special structure related to the mechanism of neutrino mass generation. We propose a framework which can realize such a relation. The main ingredients of the framework are the double seesaw mechanism, SO(10) grand unification and a hidden sector of theory. The latter is composed of singlets (fermions and bosons) of the grand unified theory (GUT) symmetry with masses between the GUT and Planck scale. The interactions in this sector obey certain symmetries $G_{\text{hidden}}$. We explore the conditions under which symmetries $G_{\text{hidden}}$ can produce flavor structures in the visible sector. Here the key elements are the basis-fixing symmetry and mediators which communicate information about properties of the hidden sector to the visible one. The interplay of SO(10) symmetry, basis-fixing symmetry identified as ${\mathbb{Z}}_2\times {\mathbb{Z}}_2$ and $G_{\text{hidden}}$ can lead to the required form of $U_X$. A different kind of new physics is responsible for generation of the CKM mixing. We present the simplest realizations of the framework which differ by nature of the mediators and by symmetries of the hidden sector.

The smallness of the ${\theta }_{13}$ mixing angle as observed in neutrino oscillation experiments can be understood through an approximated $\mu -\tau$ exchange symmetry in the neutrino mass matrix. Using recent oscillation neutrino data, but assuming no $CP$ violation, we study $\mu -\tau$ breaking parameter space to establish the conditions under which such a breaking could have a perturbative origin. According to the so-obtained conditions, we suggest that a sterile neutrino, matching LSND/MiniBooNE neutrino oscillation results, could provide the necessary ingredients to properly fix atmospheric and ${\theta }_{13}$ mixing angles to observable values, without exceeding the sterile neutrino fraction bound in solar oscillations. In such a scenario, we analyze the general effect of a fourth neutrino on the prediction for the effective $m_{ee}$ majorana mass parameter.

Many extensions of the Standard Model posit the existence of heavy particles with long lifetimes. This article presents the results of a search for events containing at least one long-lived particle that decays at a significant distance from its production point into two leptons or into five or more charged particles. This analysis uses a data sample of proton-proton collisions at $\sqrt{s}=8\mathrm{TeV}$ corresponding to an integrated luminosity of $20.3{\mathrm{fb}}^{-1}$ collected in 2012 by the ATLAS detector operating at the Large Hadron Collider. No events are observed in any of the signal regions, and limits are set on model parameters within supersymmetric scenarios involving $R$-parity violation, split supersymmetry, and gauge mediation. In some of the search channels, the trigger and search strategy are based only on the decay products of individual long-lived particles, irrespective of the rest of the event. In these cases, the provided limits can easily be reinterpreted in different scenarios.

We derive novel limits on the masses of the light and heavy Majorana neutrinos by requiring successful leptogenesis in seesaw models of minimal-flavor violation (MFV). Taking properly into account radiative flavor effects and avoiding the limitations due to a no-go theorem on leptonic asymmetries, we find that the mass of the lightest of the observable neutrinos must be smaller than $\sim 0.05\mathrm{eV}$, while the Majorana scale of lepton-number violation should be higher than $\sim {10}^{12}\mathrm{GeV}$. The latter lower bound enables one to probe the existence of possible new scales of MFV, up to energies of $\sim 100\mathrm{TeV}$, in low-energy experiments, such as $\mu \to e\gamma$ and $\mu \to e$ conversion in nuclei. Possible realizations of MFV leptogenesis in Grand Unified Theories are briefly discussed.