Inelastic dark matter reconciles the DAMA anomaly with other null direct detection experiments and points to a nonminimal structure in the dark matter sector. In addition to the dominant inelastic interaction, dark matter scattering may have a subdominant elastic component. If these elastic interactions are suppressed at low momentum transfer, they will have similar nuclear recoil spectra to inelastic scattering events. While upcoming direct detection experiments will see strong signals from such models, they may not be able to unambiguously determine the presence of the subdominant elastic scattering from the recoil spectra alone. We show that directional detection experiments can separate elastic and inelastic scattering events and discover the underlying dynamics of dark matter models.

We analyze the tension between naturalness and isospin violation in the Lee-Wick standard model (LW SM) by computing tree-level and fermionic one-loop contributions to the post-LEP electroweak parameters ($\widehat{S}$, $\widehat{T}$, $W$, and $Y$) and the $Z{b}_L{\overline{b}}_L$ coupling. The model is most natural when the LW partners of the gauge bosons and fermions are light, but small partner masses can lead to large isospin violation. The post-LEP parameters yield a simple picture in the LW SM: the gauge sector contributes to $Y$ and $W$ only, with leading contributions arising at tree level, while the fermion sector contributes to $\widehat{S}$ and $\widehat{T}$ only, with leading corrections arising at one loop. Hence, $W$ and $Y$ constrain the masses of the LW gauge bosons to satisfy $M_1$, $M_2\gtrsim 2.4\mathrm{TeV}$ at 95% C.L. Likewise, experimental limits on $\widehat{T}$ reveal that the masses of the LW fermions must satisfy $M_q$, $M_t\gtrsim 1.6\mathrm{TeV}$ at 95% C.L. if the Higgs mass is light and tend to exclude the LW SM for any LW fermion masses if the Higgs mass is heavy. Contributions from the top-quark sector to the $Z{b}_L{\overline{b}}_L$ coupling can be even more stringent, placing a lower bound of 4 TeV on the LW fermion masses at 95% C.L.

We compute masses, trilinear self-couplings, and decay widths into weak bosons of the scalar composite bosons in the case of the minimal and ultraminimal technicolor models. The masses, computed via the Bethe-Salpeter equation, turn out to be light, and the trilinear couplings smaller than the one that would be expected when compared to a fundamental standard model scalar boson with the same mass. The decay widths into electroweak bosons of the ultraminimal model scalars bosons are much smaller than the one of the minimal model.

We present a simple scenario for gauge mediated supersymmetry breaking (GMSB) where the messengers are also the fields that generate neutrino masses. We show that the simplest such scenario corresponds to the case where neutrino masses are generated through the type I and type III seesaw mechanisms. The entire supersymmetric spectrum and Higgs masses are calculable from only four input parameters. Since the electroweak symmetry is broken through a doubly radiative mechanism, meaning a nearly zero $B$ term at the messenger scale which runs down to acceptable values, one obtains quite a constrained spectrum for the supersymmetric particles whose properties we describe. We refer to this mechanism as “$\nu$ GMSB.”

We perform a global Bayesian fit of the phenomenological minimal supersymmetric standard model (pMSSM) to current indirect collider and dark matter data. The pMSSM contains the most relevant 25 weak-scale MSSM parameters, which are simultaneously fit using “nested sampling” Monte Carlo techniques in more than 15 years of CPU time. We calculate the Bayesian evidence for the pMSSM and constrain its parameters and observables in the context of two widely different, but reasonable, priors to determine which inferences are robust. We make inferences about sparticle masses, the sign of the $\mu$ parameter, the amount of fine-tuning, dark matter properties, and the prospects for direct dark matter detection without assuming a restrictive high-scale supersymmetry breaking model. We find the inferred lightest $CP$-even Higgs boson mass as an example of an approximately prior-independent observable. This analysis constitutes the first statistically convergent pMSSM global fit to all current data.

We discuss the lattice formulation of gauge theories with fermions in arbitrary representations of the color group and present in detail the implementation of the hybrid Monte Carlo (HMC)/rational HMC algorithm for simulating dynamical fermions. We discuss the validation of the implementation through an extensive set of tests and the stability of simulations by monitoring the distribution of the lowest eigenvalue of the Wilson-Dirac operator. Working with two flavors of Wilson fermions in the adjoint representation, benchmark results for realistic lattice simulations are presented. Runs are performed on different lattice sizes ranging from $4^3\times 8$ to ${24}^3\times 64$ sites. For the two smallest lattices we also report the measured values of benchmark mesonic observables. These results can be used as a baseline for rapid cross-checks of simulations in higher representations. The results presented here are the first steps toward more extensive investigations with controlled systematic errors, aiming at a detailed understanding of the phase structure of these theories, and of their viability as candidates for strong dynamics beyond the standard model.

We investigate the prompt photon photoproduction at HERA within the framework of the $k_T$-factorization QCD approach. Our consideration is based on the off-shell matrix elements for the underlying partonic subprocesses. The unintegrated parton densities in a proton and in a photon are determined using the Kimber-Martin-Ryskin prescription. Additionally, we use the Ciafaloni-Catani-Fiorani-Marchesini–evolved unintegrated gluon as well as valence and sea quark distributions in a proton. A conservative error analysis is performed. Both inclusive and associated with the hadronic jet production rates are investigated. The theoretical results are compared with the recent experimental data taken by the H1 and ZEUS Collaborations. We study also the specific kinematical properties of the photon-jet system which are strongly sensitive to the transverse momentum of incoming partons. Using the Kimber-Martin-Ryskin scheme, the contribution from the quarks emerging from the earlier steps of the parton evolution is estimated and found to be of 15%–20% approximately.

A phase $\Delta \Phi$ between amplitudes for $B^0\to K^{*0}{\pi }^0$ and $B^0\to K^{*+}{\pi }^{-}$ plays a crucial role in a method for constraining Cabibbo-Kobayashi-Maskawa parameters. We present a general argument for destructive interference between amplitudes for $B^0\to K^{*+}{\pi }^{-}$ and $B^0\to K^{*0}{\pi }^0$ forming together a smaller $I(K^{*}\pi )=3/2$ amplitude. Applying flavor SU(3) and allowing for conservative theoretical uncertainties, we obtain lower limits on $|\Delta \Phi |$ and its charge conjugate. Values of these two phases favored by the BABAR collaboration are in good agreement with our bounds.

We calculate the $\pi$, $\rho$, $\omega$, and $\gamma$ coupling constants between the heavy meson doublets $(1^{-},2^{-})$ and $(0^{-},1^{-})/(0^{+},1^{+})$ within the framework of the light-cone QCD sum rule at the leading order of heavy quark effective theory. Most of the sum rules are stable with the variations of the Borel parameter and the continuum threshold. Then we calculate the strong and electromagnetic decay widths of the $(1^{-},2^{-})$ $D$-wave heavy mesons. Their total widths are around several tens of MeV, which is helpful in the future experimental search.

We compute the mixed phase of nuclear matter and 2SC matter for different temperatures and proton fractions. After showing that the symmetry energy of the 2SC phase is, to a good approximation, 3 times larger than the one of the normal quark phase, we discuss and compare all the properties of the mixed phase with a 2SC component or a normal quark matter component. In particular, the local isospin densities of the nuclear and the quark component and the stiffness of the mixed phase are significantly different whether the 2SC phase or the normal quark phase are considered. If a strong diquark pairing is adopted for the 2SC phase, there is a possibility to eventually enter in the nuclear matter 2SC matter mixed phase in low energy heavy ions collisions experiments. Possible observables able to discern between the formation of the 2SC phase or the normal quark phase are finally discussed.

We discuss jet substructure in recombination algorithms for QCD jets and single jets from heavy particle decays. We demonstrate that the jet algorithm can introduce significant systematic effects into the substructure. By characterizing these systematic effects and the substructure from QCD, splash-in, and heavy particle decays, we identify a technique, pruning, to better identify heavy particle decays into single jets and distinguish them from QCD jets. Pruning removes protojets typical of soft, wide-angle radiation, improves the mass resolution of jets reconstructing heavy particle decays, and decreases the QCD background to these decays. We show that pruning provides significant improvements over unpruned jets in identifying top quarks and $W$ bosons and separating them from a QCD background, and may be useful in a search for heavy particles.

The quark propagator is calculated in the Nambu–Jona-Lasinio model in a self-consistent $1/N_c$-expansion at next-to-leading order. The calculations are carried out iteratively in Euclidean space. The chiral quark condensate and its dependence on temperature and chemical potential is calculated directly and compared with the mean-field results. In the chiral limit, we find a second-order phase transition at finite temperature and zero chemical potential, in agreement with universality arguments. At zero temperature and finite chemical potential, the phase transition is first order. In comparison with the mean-field results, the critical temperature and chemical potential are slightly reduced. We determine spectral functions from the Euclidean propagators by employing the maximum-entropy method. Thereby quark and meson masses are estimated and decay channels identified. For testing this method, we also apply it to evaluate perturbative spectral functions, which can be calculated directly in Minkowski space. In most cases we find that the maximum-entropy method is able to reproduce the rough features of the spectral functions, but not the details.

We present a search for nonzero ${\theta }_{13}$ and deviations of ${sin}^2{\theta }_{23}$ from 0.5 in the oscillations of atmospheric neutrino data from Super-Kamiokande I, II, and III. No distortions of the neutrino flux consistent with nonzero ${\theta }_{13}$ are found and both neutrino mass hierarchy hypotheses are in agreement with the data. The data are best fit at $\Delta m^2=2.1\times {10}^{-3}{\mathrm{eV}}^2$, ${sin}^2{\theta }_{13}=0.0$, and ${sin}^2{\theta }_{23}=0.5$. In the normal (inverted) hierarchy ${\theta }_{13}$ and $\Delta m^2$ are constrained at the one-dimensional 90% C.L. to ${sin}^2{\theta }_{13}<0.04(0.09)$ and $1.9(1.7)\times {10}^{-3}<\Delta m^2<2.6(2.7)\times {10}^{-3}{\mathrm{eV}}^2$. The atmospheric mixing angle is within $0.407\le {sin}^2{\theta }_{23}\le 0.583$ at 90% C.L.

We present results from simulations of two color QCD with two Wilson quark flavors in the presence of a quark chemical potential $\mu$ at two different lattice spacings. The equation of state, conformal anomaly, superfluid order parameter, and Polyakov line are all discussed. Our results suggest that the transitions from hadronic to quark matter and from confined to deconfined matter occur at distinct values of $\mu$, consistent with the existence of a quarkyonic phase in this model.

The fermion determinant in four-dimensional quantum electrodynamics in the presence of $O(2)\times O(3)$ symmetric background gauge fields with a nonvanishing global chiral anomaly is considered. It is shown that the leading mass singularity of the determinant’s nonperturbative part is fixed by the anomaly. It is also shown that for a large class of such fields there is at least one value of the fermion mass at which the determinant’s nonperturbative part reduces to its noninteracting value.

We consider the effect of the photon radiative correction on the vacuum energy in a superstrong magnetic field. The notion of a photon anomalous magnetic moment is analyzed and its connection with the quasiparticle character of the electromagnetic radiation is established. In the infrared domain the magnetic moment turns out to be a vector with two orthogonal components in correspondence with the cylindrical symmetry imposed by the external field. The possibility of defining such quantity in the high energy limit is studied as well. Its existence suggests that the electromagnetic radiation is a source of magnetization to the whole vacuum and thus its electron-positron zero-point energy is slightly modified. The corresponding contribution to the vacuum magnetization density is determined by considering the individual contribution of each vacuum polarization eigenmode in the Euler-Heisenberg Lagrangian. A paramagnetic response is found in one of them, whereas the remaining ones are diamagnetic. Additional issues concerning the transverse pressures are analyzed.

We consider a wide class of static spherically symmetric black holes of arbitrary dimension with a photon sphere (a hypersurface on which a massless particle can orbit the black hole on unstable circular null geodesics). This class includes various spacetimes of physical interest such as Schwarzschild, Schwarzschild-Tangherlini, and Reissner-Nordström black holes, the canonical acoustic black hole, or the Schwarzschild–de Sitter black hole. For this class of black holes, we provide general analytical expressions for the Regge poles of the $S$ matrix associated with a massless scalar field theory. This is achieved by using third-order WKB approximations to solve the associated radial wave equation. These results permit us to obtain analytically the nonlinear dispersion relation and the damping of the “surface waves” lying close to the photon sphere as well as, from Bohr-Sommerfeld–type resonance conditions, formulas beyond the leading-order terms for the complex frequencies corresponding to the weakly damped quasinormal modes.

Petrov type $D$ gravitational fields, generated by a perfect fluid with spatially homogeneous energy density and with flow lines which form a nonshearing and nonrotating timelike congruence, are reexamined. It turns out that the anisotropic such spacetimes, which comprise the vacuum $C$ metric as a limit case, can have nonzero expansion, contrary to the conclusion in the original investigation by Barnes [A. Barnes, Gen. Relativ. Gravit. 4, 105 (1973).]. Apart from the static members, this class consists of cosmological models with precisely one symmetry. The general line element is constructed and some important properties are discussed. It is also shown that purely electric Petrov type $D$ vacuum spacetimes admit shear-free normal timelike congruences everywhere, even in the nonstatic regions. This result incited to deduce intrinsic, easily testable criteria regarding shear-free normality and staticity of Petrov type $D$ spacetimes in general, which are added in an appendix.

Gravitational waves emitted by kinks on infinite strings are investigated using detailed estimations of the kink distribution on infinite strings. We find that gravitational waves from kinks can be detected by future pulsar timing experiments such as SKA for an appropriate value of the string tension, if the typical size of string loops is much smaller than the horizon at their formation. Moreover, the gravitational wave spectrum depends on the thermal history of the Universe and hence it can be used as a probe into the early evolution of the Universe.

We study the stability of the Einstein static universe in the Hořava-Lifshitz (HL) gravity and a generalized version of it formulated by Sotiriou, Visser, and Weifurtner. We find that, for the HL cosmology, there exists a stable Einstein static state if the cosmological constant $\Lambda$ is negative. The universe can stay at this stable state eternally and thus the big bang singularity can be avoided. However, in this case, the Universe can not exit to an inflationary era. For the Sotiriou, Visser, and Weifurtner HL cosmology, if the cosmic scale factor satisfies certain conditions initially, the Universe can stay at the stable state past eternally and may undergo a series of infinite, nonsingular oscillations. Once the parameter of the equation of state $w$ approaches a critical value, the stable critical point coincides with the unstable one, and the Universe enters an inflationary era. Therefore, the big bang singularity can be avoided and a subsequent inflation can occur naturally.