We study angularly excited as well as interacting nontopological solitons, the so-called $Q$ balls, and their gravitating counterparts, the so-called boson stars, in $3+1$ dimensions. $Q$ balls and boson stars carry a nonvanishing Noether charge and arise as solutions of complex scalar field models in a flat space-time background and coupled minimally to gravity, respectively. We present examples of interacting $Q$ balls that arise due to angular excitations, which are closely related to the spherical harmonics. We also construct explicit examples of rotating boson stars that interact with nonrotating boson stars. We observe that rotating boson stars tend to absorb the nonrotating ones for increasing, but reasonably small gravitational coupling. This is a new phenomenon as compared to the flat space-time limit and is related to the negative contribution of the rotation term to the energy density of the solutions. In addition, our results indicate that a system of a rotating and nonrotating boson star can become unstable if the direct interaction term in the potential is large enough. This instability is related to the appearance of ergoregions.

We consider the self-energy and the self-force for scalar massive and massless particles at rest in a class of wormhole spacetimes. We develop a general approach to obtain the self-force and apply it to the two specific profiles of the wormhole throat, namely, with singular and with smooth curvature. We found that the self-force changes its sign at the point where nonminimal coupling $\xi =1/8$ (for the massless case) and it tends to infinity for specific values of $\xi$. It may be attractive as well as repulsive depending on the profile of the throat. For the massless particle and minimal coupling case, the electromagnetic results are recovered.

The positron excess observed by the PAMELA experiment may come from dark matter annihilation, if the annihilation cross section is large enough. We show that the dark matter annihilation scenarios to explain the positron excess may also be compatible with the discrepancy of the cosmic lithium abundances between theory and observations. The winolike neutralino in the supersymmetric standard model is a good example for it. This scenario may be confirmed by Fermi satellite experiments.

We show that in expanding regions, the scale factor measure can be reformulated as a local measure: Observations are weighted by integrating their physical density along a geodesic that starts in the longest-lived metastable vacuum. This explains why some of its properties are similar to those of the causal-diamond measure. In particular, both measures are free of Boltzmann brains, subject to nearly the same conditions on vacuum stability. However, the scale factor measure assigns a much smaller probability to the observed value of the cosmological constant. The probability decreases further, similar to the inverse sixth power of the primordial density contrast, if the latter is allowed to vary.

We compute the full $\mathcal{O}({\alpha }_s)$ supersymmetric (SUSY)-QCD corrections for neutralino annihilation into massive quarks through gauge or Higgs bosons and squarks in the minimal supersymmetric standard model, including the known resummation of logarithmically enhanced terms. The numerical impact of the corrections on the extraction of SUSY mass parameters from cosmological data is analyzed for gravity-mediated SUSY-breaking scenarios and shown to be sizable, so that these corrections must be included in common analysis tools.

We complement the results for the radiative corrections to the ${\widehat{\mathbf{s}}}_2·\widehat{\mathit{l}}$ angular correlation of baryon semileptonic decays of Neri et al. [Phys. Rev. D 78, 054018 (2008)] with the final results in the rest frame of the decaying baryon. In addition, we present an analytical result which was not possible to obtain in Neri et al.’s work.

The transition magnetic dipole and electric quadrupole moments of the radiative decays of the sextet heavy flavored spin $3/2$ to the heavy spin $1/2$ baryons are calculated within the light cone QCD sum rules approach. Using the obtained results, the decay rate for these transitions are also computed and compared with the existing predictions of the other approaches.

We introduce new purely twistorial scale-invariant action describing the composite bosonic $D=4$ Nambu-Goto string with target space parametrized by the pair of $D=4$ twistors. We show that by suitable gauge fixing of local scaling one gets the bilinear twistorial action and canonical quantization rules for the two-dimensional twistor-string fields. We consider the Poisson brackets of all constraints characterizing our model and we obtain four first class constraints describing two Virasoro constraints and two $U(1)\underset{}{\overset{}{⨂}}U(1)$ Kac-Moody local phase transformations.

We investigate worlds that lie on a slice through the parameter space of the standard model over which quark masses vary. We allow as many as three quarks to participate in nuclei, while fixing the mass of the electron and the average mass of the lightest baryon flavor multiplet. We classify as congenial worlds that satisfy the environmental constraint that the quark masses allow for stable nuclei with charge one, six, and eight, making organic chemistry possible. Whether a congenial world actually produces observers capable of measuring those quark masses depends on a multitude of historical contingencies, beginning with primordial nucleosynthesis and including other astrophysical processes, which we do not explore. Such constraints may be independently superimposed on our results. Environmental constraints such as the ones we study may be combined with information about the a priori distribution of quark masses over the landscape of possible universes to determine whether the measured values of the quark masses are determined environmentally, but our analysis is independent of such an anthropic approach. We estimate baryon masses as functions of quark masses via first-order perturbation theory in flavor $SU(3)$ breaking. We estimate nuclear masses as functions of the baryon masses using two separate tools: for a nucleus made of two baryon species, when possible we consider its analog in our world, a nucleus with a similar binding energy, up to Coulomb contributions. For heavy nuclei or nuclei made of more than two baryons, we develop a generalized Weizsäcker semiempirical mass formula, in which strong kinematic flavor symmetry violation is modeled by a degenerate Fermi gas . We check for the stability of nuclei against fission, strong particle emission (analogous to $\alpha$ decay), and weak nucleon emission. For two light quarks with charges $2/3$ and $-1/3$ , we find a band of congeniality roughly 29 MeV wide in their mass difference, with our own world lying comfortably away from the edges. We also find another, less robust region of congeniality with one light, charge $-1/3$ quark, and two heavier, approximately degenerate quarks with charges $-1/3$ and $2/3$. No other assignment of light quark charges yields congenial worlds with two baryons participating in nuclei. We identify the region in quark mass space where nuclei would be made from three or more baryon species. We discuss issues relevant to the congeniality of such worlds, but a full characterization of them is left for future investigation.

We build a spherical halo model for galaxies using a general scalar-tensor theory of gravity in its Newtonian limit. The scalar field is described by a time-independent Klein-Gordon equation with a source that is coupled to the standard Poisson equation of Newtonian gravity. Our model, by construction, fits both the observed rotation velocities of stars in spirals and a typical luminosity profile. As a result, the form of the new Newtonian potential, the scalar field, and dark matter distribution in a galaxy are determined. Taking into account the constraints for the fundamental parameters of the theory $(\lambda ,\alpha )$, we analyze the influence of the scalar field in the dark matter distribution, resulting in shallow density profiles in galactic centers.

We investigate the damping of the baryon acoustic oscillations in the matter power spectrum due to the quasinonlinear clustering and redshift-space distortions by confronting the models with the observations of the Sloan Digital Sky Survey luminous red galaxy sample. The chi-squared test suggests that the observed power spectrum is better matched by models with the damping of the baryon acoustic oscillations rather than the ones without the damping.

The Breit-Wigner enhancement of the thermally averaged annihilation cross section $⟨\sigma v⟩$ is shown to provide a large boost factor when the dark matter annihilation process nears a narrow resonance. We explicitly demonstrate the evolution behavior of the Breit-Wigner enhanced $⟨\sigma v⟩$ as the function of universe temperature for both the physical and unphysical pole cases. It is found that both of the cases can lead a large enough boost factor to explain the recent PAMELA, ATIC, and PPB-BETS anomalies. We also calculate the coupling of the annihilation process, which is useful for an appropriate model building to give the desired dark matter relic density.

The coupling of an unparticle operator ${\mathcal{O}}_U$ to standard model particles opens up the possibility of unparticle decays into standard model fields. We study this issue by analyzing the pole structure (and spectral function) of the unparticle propagator, corrected to account for one-loop polarization effects from virtual standard model particles. We find that the propagator of a scalar unparticle (of scaling dimension $1\le d_U<2$) with a mass gap $m_g$ develops an isolated pole, $m_p^2-i{m}_p{\Gamma }_p$, with $m_p^2\lesssim m_g^2$ below the unparticle continuum that extends above $m_g$ (showing that the theory would be unstable without a mass gap). If that pole lies below the threshold for decay into two standard model particles, it corresponds to a stable unparticle state (and its width ${\Gamma }_p$ is zero). For $m_p^2$ above the threshold, the width is nonzero and related to the rate of the unparticle decay into standard model particles. This picture is valid for any value of $d_U$ in the considered range.

We make a full tree level study of the signatures of anomalous gauge couplings of the Higgs boson at the CERN LHC via the semileptonic decay mode in $WW$ scatterings, $pp\to W^{+}{W}^{\pm }{j}_1^f{j}_2^f\to l^{+}{\nu }_l{j}_1{j}_2{j}_1^f{j}_2^f$. Both signals and backgrounds are studied at the hadron level for the Higgs mass in the range $115\mathrm{GeV}\le m_H\le 200\mathrm{GeV}$. We carefully impose suitable kinematical cuts for suppressing the backgrounds. To the same sensitivity as in the pure leptonic mode $pp\to W^{+}{W}^{+}{j}_1^f{j}_2^f\to l^{+}{\nu }_l{l}^{+}{\nu }_l{j}_1^f{j}_2^f$, our result shows that the semileptonic mode can reduce the required integrated luminosity by a factor of 3. If the anomalous couplings in nature are actually larger than the sensitivity bounds shown in the text, the experiment can start the test for an integrated luminosity of $50{\mathrm{fb}}^{-1}$.

We study $SU(2)$ gluodynamics at finite temperature on both sides of the deconfining phase transition. We create the lattice ensembles using the tree-level tadpole-improved Symanzik action. The Neuberger overlap Dirac operator is used to determine the following three aspects of vacuum structure: (i) The topological susceptibility is evaluated at various temperatures across the phase transition, (ii) the overlap fermion spectral density is determined and found to depend on the Polyakov loop above the phase transition and (iii) the corresponding localization properties of low-lying eigenmodes are investigated. Finally, we compare with zero temperature results.

We propose a Dirac-Born-Infeld $\mathrm{\text{vertex brane}}+N_c$ fundamental strings configuration for a probe baryon in the finite-temperature thermal gauge field via AdS/CFT correspondence. In particular, we investigate properties of this configuration in ${\mathrm{QCD}}_4$ and warped ${\mathrm{AdS}}_6\times S^4$. We find that, in the D4–D8 system, a holographic probe baryon can be described as $N_c$ fundamental strings connecting through a vertex D4 brane wrapped on $S^4$. In ${\mathrm{QCD}}_4$ background, a closed vertex can exist in a confined phase but cannot exist in a deconfined phase. In the low temperature region, the screening effect still exists in the confined phase like a meson, and the vertex D4 brane dominates the baryon mass. The lower energy state corresponds to the vertex brane closer to the radial cutoff position ($r=r_c$), and the higher energy state corresponds to the vertex brane a little farther away from the cutoff position. The high energy limit of this configuration is just like the unclosed vertex brane configuration in a higher temperature deconfined phase. In warped ${\mathrm{AdS}}_6\times S^4$ background, a closed vertex can exist in a deconfined phase and the vertex contains a spike, while fundamental strings are relatively short. The screening length should be defined through the distance between the top position of the vertex spike and the boundary.

We calculate the shear viscosity of field theories with gravity duals of Gauss-Bonnet gravity with a nontrivial dilaton using anti-de Sitter/conformal field theory. We find that the dilaton field has a nontrivial contribution to the ratio of shear viscosity over entropy density, and, after imposing a causal constraint for the boundary field theory, the new lower bound $4/25\pi$, obtained from pure Gauss-Bonnet gravity, may have a small violation.

In this publication we present an extension of the standard model within the framework of Connes’ noncommutative geometry. The model presented here is based on a minimal spectral triple which contains the standard model particles, new vectorlike fermions, and a new $U(1)$ gauge subgroup. Additionally a new complex scalar field appears that couples to the right-handed neutrino, the new fermions, and the standard Higgs particle. The bosonic part of the action is given by the spectral action which also determines relations among the gauge couplings, the quartic scalar couplings, and the Yukawa couplings at a cutoff energy of $\sim {10}^{17}\mathrm{GeV}$. We investigate the renormalization group flow of these relations. The low energy behavior allows to constrain the Higgs mass, the mass of the new scalar, and the mixing between these two scalar fields.

Theories of low-energy Lorentz violation by a fixed-norm “aether” vector field with two-derivative kinetic terms have a globally bounded Hamiltonian and are perturbatively stable only if the vector is timelike and the kinetic term in the action takes the form of a sigma model. Here we investigate the phenomenological properties of this theory. We first consider the propagation of modes in the presence of gravity and show that there is a unique choice of curvature coupling that leads to a theory without superluminal modes. Experimental constraints on this theory come from a number of sources, and we examine bounds in a two-dimensional parameter space. We then consider the cosmological evolution of the aether, arguing that the vector will naturally evolve to be orthogonal to constant-density hypersurfaces in a Friedmann-Robertson-Walker cosmology. Finally, we examine cosmological evolution in the presence of an extra compact dimension of space, concluding that a vector can maintain a constant projection along the extra dimension in an expanding universe only when the expansion is exponential.