We construct boson stars in global anti–de Sitter (AdS) space and study their stability. Linear perturbation results suggest that the ground state along with the first three excited state boson stars are stable. We evolve some of these solutions and study their nonlinear stability in light of recent work [9], arguing that a weakly turbulent instability drives scalar perturbations of AdS to black hole formation. However, evolutions suggest that boson stars are nonlinearly stable and immune to the instability for sufficiently small perturbation. Furthermore, these studies find other families of initial data which similarly avoid the instability for sufficiently weak parameters. Heuristically, we argue that initial data families with widely distributed mass energy distort the spacetime sufficiently to oppose the coherent amplification favored by the instability. From the dual CFT perspective our findings suggest that there exist families of rather generic initial conditions in strongly coupled CFT (with large number of degrees of freedom) that do not thermalize in the infinite future.

Physical models for the hemispherical power asymmetry in the cosmic microwave background (CMB) reported by the Planck Collaboration must satisfy CMB constraints to the homogeneity of the Universe and quasar constraints to power asymmetries. We survey a variety of models for the power asymmetry and show that consistent models include a modulated scale-dependent isocurvature contribution to the matter power spectrum or a modulation of the reionization optical depth, gravitational-wave amplitude, or scalar spectral index. We propose further tests to distinguish between the different scenarios.

We analyze the geometric phase in the neutrino oscillation phenomenon, which follows the pion decay ${\pi }^{+}\to {\mu }^{+}+{\nu }_{\mu }$. Its value $\pi$ is consistent with the present-day global analysis of the Standard Model neutrino oscillation parameters, accounting for the nonzero value of ${\theta }_{13}$. The impact of the $CP$ violating phase $\delta$, the neutrino’s nature, and the new physics is discussed.

Based on the linear response of the fermion propagator with respect to an external field, we first derive a model-independent expression for the staggered spin susceptibility in which the influence of the full pseudoscalar vertex function is included. This expression for the staggered spin susceptibility is quite different from that given in the previous literature. The numerical values of the staggered spin susceptibility are calculated within the framework of the Dyson-Schwinger approach. Our numerical result shows that the nonperturbative dressing effects on the fermion propagator are very important when one studies the staggered spin susceptibility corresponding to the antiferromagnetic correlation in both the Nambu phase and Wigner phase.

We consider an asymptotically free vectorial $\mathrm{SU}(N_c)$ gauge theory with $N_f$ fermions in the fundamental representation and analyze higher-loop contributions to the evolution of the theory from the ultraviolet to the infrared in the limit where $N_c\to \infty$ and $N_f\to \infty$ with $r=N_f/N_c$ a fixed, finite constant. We focus on the case where the $n$-loop beta function has an infrared zero, at $\xi ={\xi }_{\mathrm{IR},n\ell }$, where $\xi =\alpha N_c$. We give results on ${\xi }_{\mathrm{IR},n\ell }$, the anomalous dimension of the fermion bilinear evaluated at ${\xi }_{\mathrm{IR},n\ell }$, denoted ${\gamma }_{\mathrm{IR},n\ell }$, and certain structural properties of the beta function, ${\beta }_{\xi }$. The approach to this limit is investigated, and it is shown that the leading correction terms are strongly suppressed, by the factor $1/N_c^2$. This provides an understanding of a type of approximate universality in calculations for moderate values of $N_c$ and $N_f$, namely, that ${\alpha }_{\mathrm{IR},n\ell }{N}_c$, ${\gamma }_{\mathrm{IR},n\ell }$, and structural properties of the beta function are similar in theories with different values of $N_c$ and $N_f$ provided that they have similar values of $N_f/N_c$. We give results up to four loops for nonsupersymmetric theories and up to three loops for supersymmetric theories.

We attempt to reconcile seemingly conflicting experimental results on the Higgs boson mass, the anomalous magnetic moment of the muon, null results in the search for supersymmetry at the LHC within the 8 TeV data and results from $B$-physics, all within the context of supersymmetric grand unified theories. Specifically, we consider a supergravity grand unification model with nonuniversal gaugino masses where we take the $\mathrm{SU}(3{)}_C$ gaugino field to be much heavier than the other gaugino and sfermion fields at the unification scale. This construction naturally leads to a large mass splitting between the slepton and squark masses, due to the mass splitting between the electroweak gauginos and the gluino. The heavy Higgs bosons and Higgsinos also follow the gluino toward large masses. We carry out a Bayesian Monte Carlo analysis of the parametric space and find that it can simultaneously explain the large Higgs mass and the anomalous magnetic moment of the muon, while producing a negligible correction to the Standard Model prediction for $\mathcal{B}r(B_s^0\to {\mu }^{+}{\mu }^{-})$. We also find that the model leads to an excess in the Higgs diphoton decay rate. A brief discussion of the possibility of detecting the light particles is given. Also discussed are the implications of the model for dark matter.

We consider supersymmetric models in which the lightest Higgs scalar can decay invisibly consistent with the constraints on the 126 GeV state discovered at the CERN LHC. We consider the invisible decay in the minimal supersymmetric standard model (MSSM), as well its extension containing an additional chiral singlet superfield, the so-called next-to-minimal or nonminimal supersymmetric standard model (NMSSM). We consider the case of MSSM with both universal as well as nonuniversal gaugino masses at the grand unified scale, and find that only an $E_6$ grand unified model with unnaturally large representation can give rise to sufficiently light neutralinos which can possibly lead to the invisible decay $h^0\to {\tilde{\chi }}_1^0{\tilde{\chi }}_1^0$. Following this, we consider the case of NMSSM in detail, where we also find that it is not possible to have the invisible decay of the lightest Higgs scalar with universal gaugino masses at the grand unified scale. We delineate the regions of the NMSSM parameter space where it is possible for the lightest Higgs boson to have a mass of about 126 GeV, and then concentrate on the region where this Higgs can decay into light neutralinos, with the soft gaugino masses $M_1$ and $M_2$ as two independent parameters, unconstrained by grand unification. We also consider, simultaneously, the other important invisible Higgs decay channel in the NMSSM, namely the decay into the lightest $CP$-odd scalars, $h_1\to a_1{a}_1$, which is studied in detail. With the invisible Higgs branching ratio being constrained by the present LHC results, we find that ${\mu }_{\mathrm{eff}}<170\mathrm{GeV}$ and $M_1<80\mathrm{GeV}$ are disfavored in NMSSM for fixed values of the other input parameters. The dependence of our results on the parameters of NMSSM is discussed in detail.

Utilizing lattice QCD results for the potential of two static antiquarks and two dynamical quarks as well as quark model techniques for the dynamics of two heavy antiquarks in a cloud of two light quarks, we are provided with an accurate framework for the study of possibly existing heavy-heavy-light-light tetraquarks. Among the possible quantum numbers of such a system, we find binding in only one channel the scalar isosinglet. Solving the Schrödinger equation for the displacement of the heavy antiquarks and taking systematic errors into account, we find an antibottom-antibottom-light-light bound state with a confidence level of around $1.8\sigma –3.0\sigma$ and binding energy of approximately 30–57 MeV.

The model of elastic scattering amplitudes dominated by the triple (at $t=0$) Pomeron pole suggested earlier is modified to confront to existing experimental data on $pp$ and $\overline{p}p$ total and differential cross sections at $\sqrt{s}\ge 19\mathrm{GeV}$ and $|t|\le 14.2{\mathrm{GeV}}^2$ including the newest TOTEM data. Predictions for the future TOTEM measurements at 13 and 14 TeV are given.

Multimegaton scale in under-ice and underwater detectors of atmospheric neutrinos with a few GeV energy threshold (PINGU, ORCA) open up new possibilities in the determination of neutrino properties, and in particular the neutrino mass hierarchy. With a dense array of optical modules it will be possible to determine the inelasticity, $y$, of the charged current ${\nu }_{\mu }$ events in addition to the neutrino energy $E_{\nu }$ and the muon zenith angle ${\theta }_{\mu }$. The discovery potential of the detectors will substantially increase with the measurement of $y$. It will enable (i) a partial separation of the neutrino and antineutrino signals, (ii) a better reconstruction of the neutrino direction, (iii) the reduction of the neutrino parameters degeneracy, (iv) a better control of systematic uncertainties, and (v) a better identification of the ${\nu }_{\mu }$ events. It will improve the sensitivity to the $CP$-violation phase. The three-dimensional $(E_{\nu },{\theta }_{\mu },y)$, ${\nu }_{\mu }$ oscillograms with the kinematical as well as the experimental smearing are computed. We present the asymmetry distributions in the $E_{\nu }-{\theta }_{\mu }$ plane for different intervals of $y$ and study their properties. We show that the inelasticity information reduces the effect of degeneracy of parameters by 30%. With the inelasticity, the total significance of establishing mass hierarchy may increase by (20–50)%, thus effectively increasing the volume of the detector by a factor of 1.5–2.

The first observation of the decay $B_s^0\to {\overline{D}}^0{K}^{-}{\pi }^{+}$ is reported. The analysis is based on a data sample, corresponding to an integrated luminosity of $1.0{\mathrm{fb}}^{-1}$ of $pp$ collisions, collected with the LHCb detector. The branching fraction relative to that of the topologically similar decay $B^0\to {\overline{D}}^0{\pi }^{+}{\pi }^{-}$ is measured to be $\frac{\mathcal{B}(B_s^0\to {\overline{D}}^0{K}^{-}{\pi }^{+})}{\mathcal{B}(B^0\to {\overline{D}}^0{\pi }^{+}{\pi }^{-})}=1.18\pm 0.05(\mathrm{stat})\pm 0.12(\mathrm{syst})$. In addition, the relative branching fraction of the decay $B^0\to {\overline{D}}^0{K}^{+}{\pi }^{-}$ is measured to be $\frac{\mathcal{B}(B^0\to {\overline{D}}^0{K}^{+}{\pi }^{-})}{\mathcal{B}(B^0\to {\overline{D}}^0{\pi }^{+}{\pi }^{-})}=0.106\pm 0.007(\mathrm{stat})\pm 0.008(\mathrm{syst})$.

Here we obtain all possible second-order theories for a rank-2 tensor which describe a massive spin-2 particle. We start with a general second-order Lagrangian with ten real parameters. The absence of lower-spin modes and the existence of two local field redefinitions leads us to only one free parameter. The solutions are split into three one-parameter classes according to the local symmetries of the massless limit. In the class which contains the usual massive Fierz-Pauli theory, the subset of spin-1 massless symmetries is maximal. In another class where the subset of spin-0 symmetries is maximal, the massless theory is invariant under Weyl transformations and the mass term does not need to fit into the form of the Fierz-Pauli mass term. In the remaining third class neither the spin-1 nor the spin-0 symmetry is maximal and we have a new family of spin-2 massive theories.

Low-lying hypernuclei ${}_{\Lambda }{}^3\mathrm{H}$, ${}_{\Sigma }{}^3{\text{}}^0\mathrm{H}$, ${}_{\Lambda }{}^3\mathrm{He}$, ${}_{\Sigma }{}^3{\text{}}^0\mathrm{He}$ are described by the relativistic nine-quark equations in the framework of the dispersion relation technique. The approximate solutions of these equations are obtained using a method based on the extraction of leading singularities of the amplitudes. The relativistic nine-quark amplitudes of hypernuclei, including the quarks of three flavors $(u,d,s)$, are calculated. The poles of these amplitudes determine the masses of hypernuclei. The mass of state ${}_{\Lambda }{}^3\mathrm{H}$ with the isospin projection $I_3=0$ and the spin-parity $J^P=\frac{1}{2}\genfrac{}{}{0ex}{}{{\mathrm{}}^{+}}{}$ is equal to $M=2991\mathrm{MeV}$.

The scalar strange-quark matrix element of the nucleon is computed with lattice QCD. A mixed-action scheme is used with domain-wall valence fermions computed on the staggered MILC sea-quark configurations. The matrix element is determined by making use of the Feynman-Hellmann theorem which relates this strange matrix element to the change in the nucleon mass with respect to the strange-quark mass. The final result of this calculation is $m_s⟨N|\overline{s}s|N⟩=48\pm 10\pm 15\mathrm{MeV}$ and, correspondingly, $f_s=m_s⟨N|\overline{s}s|N⟩/m_N=0.051\pm 0.011\pm 0.016$. Given the lack of a quantitative comparison of this phenomenologically important quantity determined from various lattice QCD calculations, we take the opportunity to present such an average. The resulting conservative determination is $f_s=0.043\pm 0.011$.

We examine the feasibility of gauge invariant descriptions of the gluon polarization following the proposal that a gauge field can be decomposed into its physical part and its pure gauge part. We show that gauge invariant angular momentum currents can be constructed from summations of gauge variant Noether currents. We present novel expressions of the pure gauge field, which are used to formulate gauge invariant descriptions of the gluon spin and the photon spin. We show that the gauge invariant extension of the Chern-Simons current can describe the spins of the Laguerre-Gauss laser modes. We also discuss the relation of gauge invariant operators and the parton distributions constructed from Dirac variables.

We propose methods to construct gauge invariant decompositions of the nucleon spin, particularly gauge invariant descriptions of the gluon polarization. We show that gauge invariant decompositions of the nucleon spin can be derived naturally from the conserved current of a generalized Lorentz transformation by the Noether theorem. We propose a gauge invariant extension of the Chern-Simons current as a possible description of the gluon spin, and we also examine the problem of gauge dependence of this extended Chern-Simons current.

A consistent nonperturbative approach (based on QFT) to neutral fermion creation (due to their magnetic moments) in strong inhomogeneous magnetic fields is considered. It is demonstrated that quantization in terms of neutral particles and antiparticles is possible in terms of the states with well-defined spin polarization. Such states are localizable and can form wave packets in a given asymptotic region. In this case, the problem can be technically reduced to the problem of charged-particle creation by an electric step. In particular, the relation to the Schwinger method of an effective action is established. As an example, we calculate neutral fermion creation from the vacuum by a linearly growing magnetic field. We show that the total number and the vacuum-to-vacuum transition probability of created pairs depend only on the gradient of the magnetic field, but not on its strength, and this fact does not depend on the spacetime dimension. We show that the created flux aimed in one of the directions is formed from fluxes of particles and antiparticles of equal intensity and with the same magnetic moments parallel to the external field. In such a flux, particle and antiparticle velocities that are perpendicular to the plane of the magnetic moment and flux direction are essentially depressed. The creation of neutral fermions with anomalous magnetic moments leads to a smoothing of the initial magnetic field, which in turn prevents the appearance of superstrong constant magnetic fields. Our estimations show that the vacuum instability with respect to the creation of neutrinos and even neutrons in strong magnetic fields of the magnetars and fields generated during a supernova explosion has to be taken into account in the astrophysics. In particular, it may be of significance for dark matter studies.

We consider the leading-order expression at weak coupling for a single-site large-$N$ gauge theory coupled to adjoint fermions. We study the case of overlap and Wilson fermions. We extend the theory to real values of the number of fermion flavors and restrict ourselves to asymptotically free theories. Using a four-dimensional density function for the distribution of the eigenvalues of the link variables, we show that it is possible to recover the infinite-volume continuum limit for a certain range of fermion flavors if we use fermions with a bare mass of zero. Our use of the four-dimensional density function is supported by a direct analysis of the lattice action.

We investigate new aspects related to the Abelian gauge-Higgs model with the addition of the Carroll-Field-Jackiw term. We focus on one-loop quantum corrections to the photon and Higgs sectors due to spontaneous breaking of gauge symmetry and show that new finite and definite Lorentz-breaking terms are induced. Specifically in the gauge sector, a $CPT$-even aether term is induced. Besides, aspects of the one-loop renormalization of the background vector-dependent terms are discussed.

We find a new class of theories of massive gravity with five propagating degrees of freedom where only rotations are preserved. Our results are based on a nonperturbative and background-independent Hamiltonian analysis. In these theories the weak field approximation is well behaved and the static gravitational potential is typically screened à la Yukawa at large distances, while at short distances no van Dam-Veltman-Zakharov discontinuity is found and there is no need to rely on nonlinear effects to pass the solar system tests. The effective field theory analysis shows that the ultraviolet cutoff is $(m{M}_{\mathrm{Pl}}{)}^{1/2}\simeq 1/\mu \mathrm{m}$, the highest possible. Thus, these theories can be studied in the weak-field regime at all the phenomenologically interesting scales and are candidates for a calculable large-distance modified gravity.