We describe in detail our calculation of the full supersymmetric QCD corrections to neutralino annihilation into heavy quarks and extend our numerical analysis of the resulting dark matter relic density to scenarios without scalar or gaugino mass unification. In these scenarios, the final state is often composed of top quarks and the annihilation proceeds through $Z^0$-boson or scalar top-quark exchanges. The impact of the corrections is again shown to be sizable, so that they must be taken into account systematically in global analyses of the supersymmetry parameter space.

We analyze asymptotic properties of higher-dimensional vacuum spacetimes admitting a “nondegenerate” geodetic multiple Weyl aligned null direction. After imposing a fall-off condition necessary for asymptotic flatness, we determine the behavior of the Weyl tensor as null infinity is approached along the Weyl aligned null direction. This demonstrates that these spacetimes do not “peel off” and do not contain gravitational radiation (in contrast to their four-dimensional counterparts). In the nontwisting case, the uniqueness of the Schwarzschild-Tangherlini metric is also proven.

We promote the Immirzi parameter to be a minimally coupled scalar field and we analyzed the Hamiltonian constraints in the framework of loop quantum gravity without the time gauge. Proper SU(2) connections can be defined and a term containing derivatives of the field $\beta$ enters into their definition. Furthermore, boost degrees of freedom are nondynamical, while the supermomentum constraints coincide with the scalar field case. Hence, the kinematical Hilbert space can be defined as for gravity in presence of a minimally coupled scalar field. Then, we analyzed the dynamical implications of this scenario and we outline how a dynamical relaxation to a nonvanishing vacuum expectation value is predicted, so recovering the standard loop quantum gravity formulation.

The Kaluza-Klein compactification in the limit of a large number of extra dimensions is studied. The starting point is the Einstein-Hilbert action plus cosmological constant in $4+\mathbf{D}$ dimensions. It is shown that in the large $\mathbf{D}$ limit the effective four-dimensional cosmological constant is of order $1/\mathbf{D}$, whereas the size of the extra dimensions remains finite. A ’t Hooft-like large $\mathbf{D}$ expansion of the effective Lagrangian for the Kaluza-Klein scalar and gauge fields arising from the dimensional reduction is considered. It is shown that the propagator of the scalar field associated to the determinant of the metric of the extra dimensions is strongly suppressed. This is an interesting result as in standard Kaluza-Klein theory this scalar degree of freedom is responsible for the constraint on the gauge fields which makes it impossible to recover the usual Yang-Mills equations. Moreover in the large $\mathbf{D}$ limit it turns out that the ultraviolet divergences due to the interactions between gauge and scalar fields are softened.

In this paper a holographic description of eternal inflation is developed. We focus on the description of an open Friedmann-Robertson-Walker (FRW) universe that results from a tunneling event in which a false vacuum with positive vacuum energy decays to a supersymmetric vacuum with vanishing cosmological constant. The observations of a “census taker” in the final vacuum can be organized into a holographic dual conformal field theory that lives on the asymptotic boundary of space. We refer to this bulk-boundary correspondence as FRW/CFT duality. The dual conformal field theory (CFT) is a Euclidean two-dimensional theory that includes a Liouville 2D gravity sector describing geometric fluctuations of the boundary. The renormalization-group flow of the theory is richer than in the AdS/CFT correspondence, and generates two space-time dimensions—one spacelike and one timelike. We discuss a number of phenomena such as bubble collisions, and the Garriga, Guth Vilenkin “persistence of memory,” from the dual viewpoint.

The unique dynamics of the tidal disruption of satellite galaxies is an extremely sensitive probe of long-range interactions between dark-matter particles. Dark-matter forces that are several percent the strength of gravity will lead to order unity changes in the ratio of the number of stars in the leading and trailing tidal streams of a satellite galaxy. The approximate symmetry of the stellar tidal streams of the Sagittarius dwarf galaxy would thus exclude attractive dark-matter forces greater than 10% the strength of gravity which would entirely eliminate the leading stream. However, recent simulations suggest that dark-matter forces 100% the strength of gravity could completely strip the stellar component of Sagittarius of its dark matter, allowing for the subsequent development of symmetric tidal streams. Here we argue that these simulations use inconsistent initial conditions corresponding to separate pure stellar and pure dark-matter satellites moving independently in the host galaxy’s halo, rather than a single disrupting composite satellite as had been intended. A new simulation with different initial conditions, in particular a much more massive satellite galaxy, might demonstrate a scenario in which symmetric tidal streams develop in the presence of large dark-matter forces. This scenario must satisfy several highly restrictive criteria described in this paper.

Cosmological departures from general relativity offer a possible explanation for the cosmic acceleration. To linear order, these departures (quantified by the model-independent parameter $\varpi$, referred to as a “gravitational slip”) amplify or suppress the growth of structure in the universe relative to what we would expect to see from a general relativistic universe lately dominated by a cosmological constant. As structures collapse and become more dense, linear perturbation theory is an inadequate descriptor of their behavior, and one must extend calculations to nonlinear order. If the effects of gravitational slip extend to these higher orders, we might expect to see a signature of $\varpi$ in the bispectrum of galaxies distributed on the sky. We solve the equations of motion for nonlinear perturbations in the presence of gravitational slip and find that, while there is an effect on the bispectrum, it is too weak to be detected with present galaxy surveys. We also develop a formalism for incorporating scale dependence into our description of gravitational slip.

The one-loop induced $Z\to gg\gamma$ and $Z^{\prime }\to gg\gamma$ decays are studied within the context of the minimal 331 model, which predicts the existence of new gauge bosons and three exotic quarks. It is found that the $Z\to gg\gamma$ decay is insensitive to the presence of the exotic quarks, as it is essentially governed by the first two families of known quarks. As to the $Z^{\prime }\to gg\gamma$ decay, it is found that the exotic quark contribution dominates and that for a heavy $Z^{\prime }$ boson it leads to a $\Gamma (Z^{\prime }\to gg\gamma )$ that is more than 1 order of magnitude larger than that associated with $\Gamma (Z^{\prime }\to ggg)$. This result may be used to distinguish a new neutral $Z^{\prime }$ boson from those models that do not introduce exotic quarks.

An on-shell renormalization program for the chargino/neutralino and the sfermion sectors within the minimal supersymmetric standard model as implemented in a fully automated code, sloops, for the calculation of one-loop processes at the colliders and in astrophysics, is presented. This is a sequel to our previous study where an on-shell renormalization of the Higgs (and the gauge/fermion) sector is performed. The issue of mixing is treated in a unified and coherent manner in all these sectors, in particular, we give some new insight into the renormalization of the mixing angle in the sfermion sector. Like with the issue of $\tan \beta$ in the Higgs sector, we discuss different schemes for the mixing in the sfermion sector. We also perform numerical comparisons between our code sloops and different results found in the literature. In particular, we consider loop corrections to the neutralino and sfermion masses, chargino pair production and stau pair production in $e^{+}{e}^{-}$ colliders as well as a few decays of the heavier chargino. For all these observables, we analyze the $\tan \beta$ scheme dependence using different definitions of this parameter and comment on the impact of using different renormalization of the mixing parameter in the sfermion sector.

Fixed-target experiments are ideally suited for discovering new MeV–GeV mass $U(1)$ gauge bosons through their kinetic mixing with the photon. In this paper, we identify the production and decay properties of new light gauge bosons that dictate fixed-target search strategies. We summarize existing limits and suggest five new experimental approaches that we anticipate can cover most of the natural parameter space, using currently operating GeV-energy beams and well-established detection methods. Such experiments are particularly timely in light of recent terrestrial and astrophysical anomalies (PAMELA, Fermi, DAMA/LIBRA, etc.) consistent with dark matter charged under a new gauge force.

The computation of the spatial string tension of finite temperature QCD is discussed in QCD and in a $\mathrm{\text{gravity}}+\mathrm{\text{scalar}}$ model of gauge/gravity duality.

We investigate the chiral phase transition in the strong coupling lattice QCD at finite temperature and density with finite coupling effects. We adopt one species of staggered fermion, and develop an analytic formulation based on strong coupling and cluster expansions. We derive the effective potential as a function of two order parameters, the chiral condensate $\sigma$ and the quark number density ${\rho }_q$, in a self-consistent treatment of the next-to-leading order (NLO) effective action terms. NLO contributions lead to modifications of quark mass, chemical potential, and the quark wave function renormalization factor. While the ratio ${\mu }_c(T=0)/T_c(\mu =0)$ is too small in the strong coupling limit, it is found to increase as $\beta =2N_c/g^2$ increases. The critical point is found to move in the lower $T$ direction as $\beta$ increases. Since the vector interaction induced by ${\rho }_q$ is shown to grow as $\beta$, the present trend is consistent with the results in Nambu-Jona-Lasinio models. The interplay between two order parameters leads to the existence of partially chiral restored matter, where effective chemical potential is automatically adjusted to the quark excitation energy.

We study the lepton number violating like-sign dilepton processes $h_1{h}_2\to l^{\pm }{l}^{\prime \pm }jjX$ and $h_1{h}_2\to l^{\pm }{l}^{\prime \pm }{W}^{\pm }X$, mediated by heavy GeV scale Majorana neutrinos. We focus on the resonantly enhanced contributions with a nearly on-mass-shell Majorana neutrino in the $s$ channel. We study the constraints on like-sign dilepton production at the Tevatron and the LHC on the basis of the existing experimental limits on the masses of heavy neutrinos and their mixings $U_{\alpha N}$ with $\alpha ={\nu }_e$, ${\nu }_{\mu }$, ${\nu }_{\tau }$. Special attention is paid to the constraints from neutrinoless double beta decay. We note that searches for like-sign $e^{\pm }{e}^{\pm }$ events at Tevatron and LHC may provide evidence of $CP$ violation in the neutrino sector. We also discuss the conditions under which it is possible to extract individual constraints on the mixing matrix elements in a model independent way.

Vortons are closed loops of superconducting strings carrying current and charge. A formalism has been developed to study vortons in terms of an elastic string approximation, but its implementation requires knowledge of the unknown equation of state, relating the string tension to the energy per unit length. Recently, a planar analogue of the vorton, known as a kinky vorton, has been introduced. In this paper we derive an exact formula for the equation of state of a kinky vorton and use it to calculate the properties of the associated elastic string, such as the transverse and longitudinal propagation speeds. In particular, the elastic string approximation predicts a complicated and highly nontrivial pattern of intervals of instability, which we are able to confirm using full field simulations. The implications of the results for vortons are also discussed.

We use the vacuum Bianchi I model as an example to investigate the concept of physical evolution in loop quantum cosmology (LQC) in the absence of the massless scalar field which has been used so far in the literature as an internal time. In order to retrieve the system dynamics when no such a suitable clock field is present, we explore different constructions of families of unitarily related partial observables. These observables are parametrized, respectively, by: (i) one of the components of the densitized triad, and (ii) its conjugate momentum; each of them playing the role of an evolution parameter. Exploiting the properties of the considered example, we investigate in detail the domains of applicability of each construction. In both cases the observables possess a neat physical interpretation only in an approximate sense. However, whereas in case (i) such interpretation is reasonably accurate only for a portion of the evolution of the universe, in case (ii) it remains so during all the evolution (at least in the physically interesting cases). The constructed families of observables are next used to describe the evolution of the Bianchi I universe. The performed analysis confirms the robustness of the bounces, also in absence of matter fields, as well as the preservation of the semiclassicality through them. The concept of evolution studied here and the presented construction of observables are applicable to a wide class of models in LQC, including quantizations of the Bianchi I model obtained with other prescriptions for the improved dynamics.

We calculate the Sivers distribution functions induced by the final-state interaction due to one-gluon exchange in diquark models of a nucleon structure, treating the cases of scalar and axial-vector diquarks with both dipole and Gaussian form factors. We use these distribution functions to calculate the Sivers single-spin asymmetries for inclusive pion and kaon production in deep-inelastic scattering. We compare our calculations with the results of HERMES and COMPASS, finding good agreement for ${\pi }^{+}$ production at HERMES, and qualitative agreement for ${\pi }^0$ and $K^{+}$ production. Our predictions for pion and kaon production at COMPASS could be probed with increased statistics. The successful comparison of our calculations with the HERMES data constitutes prima facie evidence that the quarks in the nucleon have some orbital angular momentum in the infinite-momentum frame.

A general formalism for the evaluation of time-reversal odd parton distributions is applied here to calculate the Boer-Mulders function. The same formalism when applied to evaluate the Sivers function led to results which fulfill the Burkardt sum rule quite well. The calculation here has been performed for two different models of proton structure: a constituent quark model and the MIT bag model. In the latter case, important differences are found with respect to a previous evaluation in the same framework, a feature already encountered in the calculation of the Sivers function. The results obtained are consistent with the present wisdom, i.e., the contributions for the $u$ and $d$ flavors turn out to have the same sign, following the pattern suggested analyzing the model-independent features of the impact parameter dependent generalized parton distributions. It is therefore confirmed that the present approach is suitable for the analysis of time-reversal odd distribution functions. A critical comparison between the outcomes of the two models, as well as between the results of the calculations for the Sivers and Boer-Mulders functions, is also carried out.

Within the framework of QCD factorization (QCDF), power corrections due to penguin annihilation can account for the observed rates of penguin-dominated two-body decays of $B$ mesons and direct $CP$ asymmetries $A_{CP}(K^{-}{\pi }^{+})$, $A_{CP}(K^{*-}{\pi }^{+})$, $A_{CP}(K^{-}{\rho }^0)$ and $A_{CP}({\pi }^{+}{\pi }^{-})$. However, the predicted direct $CP$-violating effects in QCDF for $B^{-}\to K^{-}{\pi }^0$, $K^{-}\eta$, ${\pi }^{-}\eta$ and ${\overline{B}}^0\to {\pi }^0{\pi }^0$ are wrong in signs when confronted with experiment. We show that subleading $1/m_b$ power corrections to the color-suppressed tree amplitude due to spectator scattering or final-state interactions will yield correct signs for aforementioned $CP$ asymmetries and accommodate the observed ${\pi }^0{\pi }^0$ and ${\rho }^0{\pi }^0$ rates simultaneously. Implications are discussed.

The backreaction on black holes due to dragging heavy, rather than test, objects is discussed. As a case study, a five-dimensional regular black Saturn system where the central black hole has vanishing intrinsic angular momentum, $J^{\mathrm{BH}}=0$, is considered. It is shown that there is a correlation between the sign of two response functions. One is interpreted as a moment of inertia of the black ring in the black Saturn system. The other measures the variation of the black ring horizon angular velocity with the central black hole mass, for fixed ring mass and angular momentum. The two different phases defined by these response functions collapse, for small central black hole mass, to the thin and fat ring phases. In the fat phase, the zero area limit of the black Saturn ring has reduced spin $j^2>1$, which is related to the behavior of the ring angular velocity. Using the “gravitomagnetic clock effect,” for which a universality property is exhibited, it is shown that frame dragging measured by an asymptotic observer decreases, in both phases, when the central black hole mass increases, for fixed ring mass and angular momentum. A close parallelism between the results for the fat phase and those obtained recently for the double Kerr solution is drawn, considering also a regular black Saturn system with $J^{\mathrm{BH}}\ne 0$.

In this paper, we present the results of our analysis of the growth and decay of black holes possibly produced at the Large Hadron Collider, based on our previous study of black holes in the context of the warped brane-world scenario. The black hole mass accretion and decay is obtained as a function of time, and the maximum black hole mass are obtained as a function of a critical mass parameter. The latter occurs in our expression for the luminosity and is related to the size of extra-dimensional corrections to Newton’s law. Based on this analysis, we argue against the possibility of catastrophic black hole growth at the LHC.