To investigate the imprint on the gravitational-wave emission from extreme mass ratio inspirals (EMRIs) in nonpure Kerr spacetimes, we have studied the kludge waveforms generated in highly accurate, numerically generated spacetimes containing a black hole and a self-gravitating, homogeneous torus with comparable mass and spin. In order to maximize their impact on the produced waveforms, we have considered tori that are compact, massive, and close to the central black hole, investigating under what conditions the LISA experiment could detect their presence. Our results show that for a large portion of the space of parameters the waveforms produced by EMRIs in these black hole-torus systems are indistinguishable from pure Kerr waveforms. Hence, a “confusion problem” will be present for observations carried out over a time scale below or comparable to the dephasing time.

We study a scenario for high energy heavy ion collisions that leads to the formation of a strong coupling deconfined phase in which the lightest glueballs are numerous and stable. We analyze how their properties manifest themselves in experimental spectra and show that they provide a good signature for color deconfinement.

Little Higgs models with $T$-parity may provide us with a new source of lepton flavor violation, as such, in this paper we consider the anomalous magnetic moment of the muon $(g-2{)}_{\mu }$ and the lepton flavor violating decays $\mu \to e\gamma$ and $\tau \to \mu \gamma$ in the little Higgs model with $T$-parity [A. Goyal, hep-ph/0609095.]. Our results show that the present experimental constraints of $\mu \to e\gamma$ are a much more useful tool for constraining the new sources of flavor violation, than from the other processes considered here, which are present in $T$-parity models.

In this article, we explore the interplay between searches for supersymmetric particles and Higgs bosons at hadron colliders (the Tevatron and the LHC) and direct dark matter searches (such as CDMS, ZEPLIN, XENON, EDELWEISS, CRESST, WARP and others). We focus on collider searches for heavy MSSM Higgs bosons $(A,H,H^{\pm })$ and how the prospects for these searches are impacted by direct dark matter limits and vice versa. We find that the prospects of these two experimental programs are highly interrelated. A positive detection of $A$, $H$ or $H^{\pm }$ at the Tevatron would dramatically enhance the prospects for a near future direct discovery of neutralino dark matter. Similarly, a positive direct detection of neutralino dark matter would enhance the prospects of discovering heavy MSSM Higgs bosons at the Tevatron or the LHC. Combining the information obtained from both types of experimental searches will enable us to learn more about the nature of supersymmetry.

Supersymmetry without $R$-parity predicts tree-level quark flavor violation. We present a potential signal of single bottom production at electron-positron colliders with energies in the range 6 to 20 GeV. Taking into account rare decay limits, it should be detectable with the current BABAR and Belle data samples.

We discuss the net quark and isovector fluctuations as well as off-diagonal quark flavor susceptibilities along the chiral phase transition line in the Nambu-Jona-Lasinio (NJL) model. The model is formulated at nonzero quark and isospin chemical potentials with nonvanishing vector couplings in the isoscalar and isovector channels. We study the influence of the quark chemical potential on the quark flavor susceptibilities in detail and the dependence of the results on model parameters as well as on the quark mass. The NJL model findings are compared with recent lattice results obtained in two-flavor QCD at finite chemical potential. On a qualitative level, the NJL model provides a consistent description of the dependence of quark number fluctuations on temperature and baryon chemical potential. The phase diagram and the position of the tricritical point in the NJL model are also discussed for different parameter sets.

AdS waves and $pp$-waves can only be supported by pure radiation fields, for which the only nonvanishing component of the energy-momentum tensor is the energy density along the retarded time. We show that the nonminimal coupling of self-gravitating scalar fields to the higher-dimensional versions of these exact gravitational waves can be done consistently. In both cases, the resulting pure radiation constraints completely fix the scalar field dependence and the form of the allowed self-interactions. More significantly, we establish that the two sets of pure radiation constraints are conformally related for any nonminimal coupling, in spite of the fact that the involved gravitational fields are not necessarily related. In this correspondence, the potential supporting the AdS waves emerges from the self-interaction associated to the $pp$-waves and a self-dual condition naturally satisfied by the $pp$-wave scalar fields.

Zamolodchikov’s c-theorem type argument (and also string theory effective action constructions) imply that the RG flow in 2d sigma model should be a gradient one to all loop orders. However, the monotonicity of the flow of the target-space metric is not obvious since the metric on the space of metric-dilaton couplings is indefinite. To leading (one-loop) order when the RG flow is simply the Ricci flow the monotonicity was proved by Perelman [G. Perelman, math.dg/0211159.] by constructing an “entropy” functional which is essentially the metric-dilaton action extremized with respect to the dilaton with a condition that the target-space volume is fixed. We discuss how to generalize the Perelman’s construction to all loop orders (i.e. all orders in ${\alpha }^{\prime }$). The resulting entropy is equal to minus the central charge at the fixed points, in agreement with the general claim of the c-theorem.

Warped configurations admitting pairs of gravitating defects are analyzed. After devising a general method for the construction of multidefects, specific examples are presented in the case of higher-dimensional Einstein-Hilbert gravity. The obtained profiles describe diverse physical situations such as (topological) kink-antikink systems, pairs of nontopological solitons, and bound configurations of a kink and of a nontopological soliton. In all the mentioned cases the geometry is always well behaved (all relevant curvature invariants are regular) and tends to five-dimensional anti-de Sitter space-time for large asymptotic values of the bulk coordinate. Particular classes of solutions can be generalized to the framework where the gravity part of the action includes, as a correction, the Euler-Gauss-Bonnet combination. After scrutinizing the structure of the zero modes, the obtained results are compared with conventional gravitating configurations containing a single topological defect.

We study the loop corrections to potentials of complex or coupled real scalar fields used in cosmology to account for dark energy, dark matter, or dark fluid. We show that the SUGRA quintessence and dark matter scalar field potentials are stable against the quantum fluctuations, and we propose solutions to the instability of the potentials of coupled quintessence and dark fluid scalar fields. We also find that a coupling to fermions is very restricted, unless this coupling has a structure which already exists in the scalar field potential or which can be compensated by higher order corrections. Finally, we study the influence of the curvature and kinetic term corrections.

We examine the scale dependence of dark matter halo and galaxy clustering on very large scales ($0.01<k[h{\mathrm{Mpc}}^{-1}]<0.15$), due to nonlinear effects from dynamics and halo bias. We pursue a two line offensive: high-resolution numerical simulations are used to establish some old and some new results, and an analytic model is developed to understand their origins. Our simulations show: (i) that the $z=0$ dark matter power spectrum is suppressed relative to linear theory by $\sim 5\%$ on scales $0.05<k[h{\mathrm{Mpc}}^{-1}]<0.075$; (ii) that, indeed, halo bias is nonlinear over the scales we probe and that the scale dependence is a strong function of halo mass. High mass haloes show no suppression of power on scales $k<0.07[h{\mathrm{Mpc}}^{-1}]$, and only show amplification on smaller scales, whereas low mass haloes show strong, $\sim 5\%–10\%$, suppression over the range $0.05<k[h{\mathrm{Mpc}}^{-1}]<0.15$. These results were primarily established through the use of the cross-power spectrum of dark matter and haloes, which circumvents the thorny issue of shot-noise correction. The halo-halo power spectrum, however, is highly sensitive to the shot-noise correction; we show that halo exclusion effects make this sub-Poissonian and a new correction is presented. Our results have special relevance for studies of the baryon acoustic oscillation features in the halo power spectra. Nonlinear mode-mode coupling: (i) damps these features on progressively larger scales as halo mass increases; (ii) produces small shifts in the positions of the peaks and troughs which depend on halo mass. We show that these effects on halo clustering are important over the redshift range relevant to such studies $(0<z<2)$, and so will need to be accounted for when extracting information from precision measurements of galaxy clustering. Our analytic model is described in the language of the “halo model.” The halo-halo clustering term is propagated into the nonlinear regime using “1-loop” perturbation theory and a nonlinear halo bias model. Galaxies are then inserted into haloes through the halo occupation distribution. We show that, with nonlinear bias parameters derived from simulations, this model produces predictions that are qualitatively in agreement with our numerical results. We then use it to show that the power spectra of red and blue galaxies depend differently on scale, thus underscoring the fact that proper modeling of nonlinear bias parameters will be crucial to derive reliable cosmological constraints. In addition to showing that the bias on very large scales is not simply linear, the model also shows that the halo-halo and halo-dark matter spectra do not measure precisely the same thing. This complicates interpretation of clustering in terms of the stochasticity of bias. However, because the shot-noise correction is nontrivial, evidence for this in the simulations is marginal.

We present upper limits on line emission in the Cosmic X-ray background (CXB) that would be produced by decay of sterile neutrino dark matter. We employ the spectra of the unresolved component of the CXB in the Chandra Deep Fields North and South obtained with the Chandra CCD detector in the $E=0.8–9\mathrm{keV}$ band. The expected decay flux comes from the dark matter on the lines of sight through the Milky Way galactic halo. Our constraints on the sterile neutrino decay rate are sensitive to the modeling of the Milky Way halo. The highest halo mass estimates provide a limit on the sterile neutrino mass of $m_s<2.9\mathrm{keV}$ in the Dodelson-Widrow production model, while the lowest halo mass estimates provide the conservative limit of $m_s<5.7\mathrm{keV}$ ($2\sigma$). We also discuss constraints from a short observation of the softer ($E<1\mathrm{keV}$) X-ray background with a rocket-borne calorimeter by McCammon and collaborators.

The two-loop ultrasoft contributions to the next-to-leading logarithmic (NLL) running of the QCD potentials at order $v^2$ are determined. The results represent an important step towards the next-to-next-to-leading logarithmic (NNLL) description of heavy quark pair production and annihilation close to threshold.

We use the interacting instanton liquid model (IILM) as a tool to study the role played by the chiral interactions in the lowest-lying vector and axial-vector meson resonances. We find that narrow $a_1$ and $\rho$ meson resonances can be generated by instanton-induced chiral forces, even in the absence of confinement. In the IILM, these hadrons are found to have masses only about 30% larger than the experimental value and small width $\lesssim 10–50\mathrm{MeV}$. This result suggests that chiral interactions are very important in these systems and provide most of their mass. We explore the decaying patterns of the $\rho$ meson, in the absence of confinement. We argue that, in our model where only chiral forces are switched on, this meson decays dissociating into its quark-antiquark constituents.

We show that a resummation model for the evolution kernel at small $x$ creates a bridge between the weak and strong couplings. The resummation model embodies DGLAP and BFKL anomalous dimensions at leading logarithmic orders, as well as a kinematical constraint on the real emission part of the kernel. In the case of pure gluodynamics the strong coupling limit of the Pomeron intercept is consistent with the exchange of the spin-two, colorless particle.

We study the higher derivative corrections that occur in type II superstring theories in ten dimensions or less. Assuming invariance under a discrete duality group $G(\mathbf{Z})$ we show that the generic functions of the scalar fields that occur can be identified with automorphic forms. We then give a systematic method to construct automorphic forms from a given group $G(\mathbf{Z})$ together with a chosen subgroup $H$ and a linear representation of $G(\mathbf{Z})$. This construction is based on the theory of nonlinear realizations and we find that the automorphic forms contain the weights of $G$. We also carry out the dimensional reduction of the generic higher derivative corrections of the IIB theory to three dimensions and find that the weights of $E_8$ occur generalizing previous results of the authors on M theory. Since the automorphic forms of this theory contain the weights of $E_8$ we can interpret the occurrence of weights in the dimensional reduction as evidence for an underlying U-duality symmetry.

We determine torsion class constraints for the supergravity background produced by D6-branes wrapping special Lagrangian cycles in a Calabi-Yau 3-fold. We employ a recently introduced method which involves probing the putative background by all possible supersymmetric brane configurations. We then lift this background to 11 dimensions to a product of 4-d Minkowski space and a 7-fold of $G_2$ holonomy. The latter is a particular U(1) bundle over an almost complex manifold of SU(3) structure with specific torsion class constraints. We construct the closed 3- and 4-forms which calibrate the 3- and 4-cycles in the $G_2$ holonomy manifold.

We consider the contribution of the Urca-type processes to the bulk viscosity of several spin-one color-superconducting phases of dense two-flavor quark matter. In the so-called transverse phases which are suggested to be energetically favorable at asymptotic densities, the presence of ungapped quasiparticle modes prevents that spin-one color superconductivity has a large effect on the bulk viscosity. When all modes are gapped, as for one particular color-spin-locked phase, the effect on the viscosity can be quite large, which may have important phenomenological implications.

We present the first field-theoretic calculations of the contribution made by cosmic strings to the temperature power spectrum of the cosmic microwave background (CMB). Unlike previous work, in which strings were modeled as idealized one-dimensional objects, we evolve the simplest example of an underlying field theory containing local U(1) strings, the Abelian Higgs model. Limitations imposed by finite computational volumes are overcome using the scaling property of string networks and a further extrapolation related to the lessening of the string width in comoving coordinates. The strings and their decay products, which are automatically included in the field theory approach, source metric perturbations via their energy-momentum tensor, the unequal-time correlation functions of which are used as input into the CMB calculation phase. These calculations involve the use of a modified version of CMBEASY, with results provided over the full range of relevant scales. We find that the string tension $\mu$ required to normalize to the WMAP 3-year data at multipole $\ell =10$ is $G\mu =[2.04\pm 0.06(\mathrm{stat}.)\pm 0.12(\mathrm{sys}.)]\times {10}^{-6}$, where we have quoted statistical and systematic errors separately, and $G$ is Newton’s constant. This is a factor 2–3 higher than values in current circulation.