The effects of astrophysical uncertainties on the exclusion limits at dark matter direct detection experiments are investigated for three scenarios: elastic, momentum dependent, and inelastically scattering dark matter. We find that varying the dark matter galactic escape velocity and the Sun’s circular velocity can lead to significant variations in the exclusion limits for light ($\lesssim 10\mathrm{GeV}$) elastic and inelastic scattering dark matter. We also calculate the limits using 100 velocity distributions extracted from the Via Lactea II and GHALO N-body simulations and find that a Maxwell-Boltzmann distribution with the same astrophysical parameters generally sets less constraining limits. The elastic and momentum dependent limits remain robust for masses $\gtrsim 50\mathrm{GeV}$ under variations of the astrophysical parameters and the form of the velocity distribution.

We study the gauge sector of minimal walking technicolor, which is an $SU(2)$ gauge theory with $n_f=2$ flavors of Wilson fermions in the adjoint representation. Numerical simulations are performed on lattices $N_t\times N_s^3$, with $N_s$ ranging from 8 to 16 and $N_t=2N_s$, at fixed $\beta =2.25$, and varying the fermion bare mass $m_0$, so that our numerical results cover the full range of fermion masses from the quenched region to the chiral limit. We present results for the string tension and the glueball spectrum. A comparison of mesonic and gluonic observables leads to the conclusion that the infrared dynamics is given by an $SU(2)$ pure Yang-Mills theory with a typical energy scale for the spectrum sliding to zero with the fermion mass. The typical mesonic mass scale is proportional to and much larger than this gluonic scale. Our findings are compatible with a scenario in which the massless theory is conformal in the infrared. An analysis of the scaling of the string tension with the fermion mass toward the massless limit allows us to extract the chiral condensate anomalous dimension ${\gamma }_{*}$, which is found to be ${\gamma }_{*}=0.22\pm 0.06$.

We investigate the structure and the novel emerging features of the mesonic nonsinglet spectrum of the minimal walking technicolor theory. Precision measurements in the nonsinglet pseudoscalar and vector channels are compared to the expectations for an IR-conformal field theory and a QCD-like theory. Our results favor a scenario in which minimal walking technicolor is (almost) conformal in the infrared, while spontaneous chiral symmetry breaking seems less plausible.

We study the equation of state at finite temperature and density in two-flavor QCD with the renormalization group improved gluon action and the clover-improved Wilson quark action on a ${16}^3\times 4$ lattice. Along the lines of constant physics at $m_{\mathrm{PS}}/m_{\mathrm{V}}=0.65$ and 0.80, we compute the second and forth derivatives of the grand canonical partition function with respect to the quark chemical potential ${\mu }_q=({\mu }_u+{\mu }_d)/2$ and the isospin chemical potential ${\mu }_I=({\mu }_u-{\mu }_d)/2$ at vanishing chemical potentials, and study the behaviors of thermodynamic quantities at finite ${\mu }_q$ using these derivatives for the case ${\mu }_I=0$. In particular, we study density fluctuations at nonezero temperature and density by calculating the quark number and isospin susceptibilities and their derivatives with respect to ${\mu }_q$. To suppress statistical fluctuations, we also examine new techniques applicable at low densities. We find a large enhancement in the fluctuation of the quark number when the density increased near the pseudocritical temperature, suggesting a critical point at finite ${\mu }_q$ terminating the first order transition line between hadronic and quark-gluon-plasma phases. This result agrees with the previous results using staggered-type quark actions qualitatively. Furthermore, we study heavy-quark free energies and Debye screening masses at finite density by measuring the first and second derivatives of these quantities for various color channels of heavy quark-quark and quark-antiquark pairs. The results suggest that, to the leading order of ${\mu }_q$, the interaction between two quarks becomes stronger at finite densities, while that between quark and antiquark becomes weaker.

We present a complete next-to-leading order (NLO) QCD calculation to a heavy resonance production and decay into a top quark pair at the LHC, where the resonance could be either a Randall-Sundrum Kaluza-Klein graviton $G$ or an extra gauge boson $Z^{\prime }$. The complete NLO QCD corrections can enhance the total cross sections by about 80%–100% and 20%–40% for the $G$ and the $Z^{\prime }$, respectively, depending on the resonance mass. We also explore in detail the NLO corrections to the polar angle distributions of the top quark, and our results show that the shapes of the NLO distributions can be different from the leading order ones for the Kaluza-Klein graviton. Moreover, we study the NLO corrections to the spin correlations of the top quark pair production via the above process, and find that the corrections are small.

When the neutrino mass eigenstate ${\nu }_2$ is trimaximally mixed, the mixing matrix is called trimaximal. The middle column of the trimaximal mixing matrix is identical to tribimaximal mixing and the other two columns are subject to unitarity constraints. This corresponds to a mixing matrix with four independent parameters in the most general case. Apart from the two Majorana phases, the mixing matrix has only one free parameter in the $CP$ conserving limit. Trimaximality results in interesting interplay between mixing angles and $CP$ violation. A notion of maximal $CP$ violation naturally emerges here: $CP$ violation is maximal for maximal 2–3 mixing. Similarly, there is a natural constraint on the deviation from maximal 2–3 mixing which takes its maximal value in the $CP$ conserving limit.

We report on a measurement of the ${\rm Y}(1\mathrm{S}+2\mathrm{S}+3\mathrm{S})\to e^{+}{e}^{-}$ cross section at midrapidity in $p+p$ collisions at $\sqrt{s}=200\mathrm{GeV}$. We find the cross section to be $114\pm 38(\mathrm{stat}+\mathrm{\text{fit}}{)}_{-24}^{+23}(\mathrm{syst})\mathrm{pb}$. Perturbative QCD calculations at next-to-leading order in the color evaporation model are in agreement with our measurement, while calculations in the color singlet model underestimate it by $2\sigma$. Our result is consistent with the trend seen in world data as a function of the center-of-mass energy of the collision and extends the availability of ${\rm Y}$ data to RHIC energies. The dielectron continuum in the invariant-mass range near the ${\rm Y}$ is also studied to obtain a combined yield of $e^{+}{e}^{-}$ pairs from the sum of the Drell-Yan process and $b\mathrm{\text{−}}\overline{b}$ production.

We present measurements of $B$-meson decays to the final states ${\eta }^{\prime }\rho$, ${\eta }^{\prime }{f}_0$, and ${\eta }^{\prime }{K}^{*}$, where $K^{*}$ stands for a vector, scalar, or tensor strange meson. We observe a significant signal or evidence for ${\eta }^{\prime }{\rho }^{+}$ and all the ${\eta }^{\prime }{K}^{*}$ channels. We also measure, where applicable, the charge asymmetries, finding results consistent with no direct $CP$ violation in all cases. The measurements are performed on a data sample consisting of $467\times {10}^6$ $B\overline{B}$ pairs, collected with the BABAR detector at the PEP-II $e^{+}{e}^{-}$ collider at the SLAC National Accelerator Laboratory. Our results favor the theoretical predictions from perturbative QCD and QCD factorization and we observe an enhancement of the tensor $K_2^{*}(1430)$ with respect to the vector $K^{*}(892)$ component.

We study the fermionic spectral function in a holographic superconductor model. At zero temperature, there is no horizon and hence the entropy of the system is zero after the backreaction of the condensate is taken into account. We find the system exhibits the famous peak-dip-hump lineshape with a sharp low-energy peak followed by a dip and then a hump at higher energies. This feature is widely observed in the spectrum of several high-$T_c$ superconductors.

In this paper we use anti-de Sitter/conformal field theory correspondence ideas in conjunction with insights from finite-temperature real-time field theory formalism to compute 3-point correlators of $\mathcal{N}=4$ super Yang-Mills operators, in real time and at finite temperature. To this end, we propose that the gravity field action is integrated only over the right and left quadrants of the Penrose diagram of the anti-de Sitter-Schwarzschild background, with a relative sign between the two terms. For concreteness we consider the case of a scalar field in the black hole background. Using the scalar field Schwinger-Keldysh bulk-to-boundary propagators, we give the general expression of a 3-point real-time Green’s correlator. We then note that this particular prescription amounts to adapting the finite-temperature analog of Veltman’s circling rules to tree-level Witten diagrams, and comment on the retarded and Feynman scalar bulk-to-boundary propagators. We subject our prescription to several checks: Kubo-Martin-Schwinger identities, the largest time equation, and the zero-temperature limit. When specializing to a particular retarded (causal) 3-point function, we find a very simple answer: the momentum-space correlator is given by three causal (two advanced and one retarded) bulk-to-boundary propagators, meeting at a vertex point which is integrated from spatial infinity to the horizon only. This result is expected based on analyticity, since the retarded n-point functions are obtained by analytic continuation from the imaginary-time Green’s function, and based on causality considerations.

Current spectral simulations of Einstein’s equations require writing the equations in first-order form, potentially introducing instabilities and inefficiencies. We present a new penalty method for pseudospectral evolutions of second order in space wave equations. The penalties are constructed as functions of Legendre polynomials and are added to the equations of motion everywhere, not only on the boundaries. Using energy methods, we prove semidiscrete stability of the new method for the scalar wave equation in flat space and show how it can be applied to the scalar wave on a curved background. Numerical results demonstrating stability and convergence for multidomain second-order scalar wave evolutions are also presented. This work provides a foundation for treating Einstein’s equations directly in second-order form by spectral methods.

The Einstein-Hilbert action and its natural generalizations to higher dimensions (like the Lanczos-Lovelock action) have certain peculiar features. All of them can be separated into a bulk and a surface term, with a specific (“holographic”) relationship between the two, so that either term can be used to extract information about the other. Further, the surface term leads to entropy of the horizons on shell. It has been argued in the past that these features are impossible to understand in the conventional approach but find a natural explanation if we consider gravity as an emergent phenomenon. We provide further support for this point of view in this paper. We describe an alternative decomposition of the Einstein-Hilbert action and the Lanczos-Lovelock action into a new pair of surface and bulk terms, such that the surface term becomes the Wald entropy on a horizon and the bulk term is the energy density (which is the Arnowitt-Deser-Misner Hamiltonian density for Einstein gravity). We show that this new pair also obeys a holographic relationship, and we give a thermodynamic interpretation of this relation in this context. Since the bulk and surface terms, in this decomposition, are related to the energy and entropy, the holographic condition can be thought of as analogous to inverting the expression for entropy given as a function of energy $S=S(E,V)$ to obtain the energy $E=E(S,V)$ in terms of the entropy in a normal thermodynamic system. Thus the holographic nature of the action allows us to relate the descriptions of the same system in terms of two different thermodynamic potentials. Some further possible generalizations and implications are discussed.

We consider static, axisymmetric, thick-brane solutions on higher-dimensional, spherically symmetric black hole backgrounds. It was found recently [V. G. Czinner and A. Flachi, Phys. Rev. D 80, 104017 (2009).], that in cases in which the thick brane has more than two spacelike dimensions, perturbative approaches break down around the corresponding thin solutions for Minkowski-type topologies. This behavior is a consequence of the fact that thin solutions are not smooth at the axis, and for a general discussion of possible phase transitions in the system, one needs to use a nonperturbative approach. In the present paper, we provide an exact, numerical solution of the problem both for black hole- and Minkowski-type topologies with an arbitrary number of brane and bulk dimensions. We also illustrate a topology change transition in the system for a five-dimensional brane embedded in a six-dimensional bulk.

The confinement of electromagnetic field is studied in axial symmetrical, warped, six-dimensional brane world, using a recently proposed topological Abelian string-vortex solution as background. It was found, that the massless gauge field fluctuations follow four-dimensional Maxwell equations in the Lorenz gauge. The massless zero mode is localized when the thickness of the string vortex is less than $5\beta /4\pi e^2{v}^2$ and there are no other localized massless modes. There is also an infinite of nonlocalized massive Fourier modes, that follow four-dimensional Proca equations with a continuous spectrum. To compute the corrections to the Coulomb potential, a radial cutoff was introduced, in order to achieve a discrete mass spectrum. As a main result, a $\frac{R_o}{\beta R^2}$ correction was found for the four-dimensional effective Coulomb law; the result is in correspondence with the observed behavior of the Coulomb potential at today’s measurable distances.

The quantum theory of cosmological perturbations in single-field inflation is formulated in terms of a path integral. Starting from a canonical formulation, we show how the free propagators can be obtained from the well-known gauge-invariant quadratic action for scalar and tensor perturbations, and determine the interactions to arbitrary order. This approach does not require the explicit solution of the energy and momentum constraints, a novel feature which simplifies the determination of the interaction vertices. The constraints and the necessary imposition of gauge conditions is reflected in the appearance of various commuting and anticommuting auxiliary fields in the action. These auxiliary fields are not propagating physical degrees of freedom but need to be included in internal lines and loops in a diagrammatic expansion. To illustrate the formalism we discuss the tree-level three-point and four-point functions of the inflaton perturbations, reproducing the results already obtained by the methods used in the current literature. Loop calculations are left for future work.

We consider cosmologies in which a dark-energy scalar field interacts with cold dark matter. The growth of perturbations is followed beyond the linear level by means of the time-renormalization-group method, which is extended to describe a multicomponent matter sector. Even in the absence of the extra interaction, a scale-dependent bias is generated as a consequence of the different initial conditions for baryons and dark matter after decoupling. The effect is enhanced significantly by the extra coupling and can be at the 2%–3% level in the range of scales of baryonic acoustic oscillations. We compare our results with $N$-body simulations, finding very good agreement.

We find exact power-law solutions for scalar-tensor theories and clarify the conditions under which they can account for an accelerated expansion of the Universe. These solutions have the property that the signs of both the Hubble rate and the deceleration parameter in the Jordan frame may be different from the signs of their Einstein-frame counterparts. For special parameter combinations we identify these solutions with asymptotic attractors that have been obtained in the literature through dynamical-system analysis. We establish an effective general-relativistic description for which the geometrical equivalent of dark energy is associated with a time dependent equation of state. The present value of the latter is consistent with the observed cosmological “constant.” We demonstrate that this type of power-law solution for accelerated expansion cannot be realized in $f(R)$ theories.

The positron fraction observed by PAMELA and other experiments up to $\sim 100\mathrm{GeV}$ is analyzed in terms of models of cosmic-ray propagation. It is shown that generically we expect the positron fraction to reach $\sim 0.6$ at energies of several TeV, and its energy dependence bears an intimate but subtle connection with that of the boron to carbon ratio in cosmic rays. The observed positron fraction can be fit in a model that assumes a significant fraction of the boron below $\sim 10\mathrm{GeV}$ is generated through spallation of cosmic-ray nuclei in a cocoonlike region surrounding the sources, and the positrons of energy higher than a few GeV are almost exclusively generated through cosmic-ray interactions in the general interstellar medium. Such a model is consistent with the bounds on cosmic-ray anisotropies and other observations.

We present theory and algorithms to perform an all-sky coherent search for periodic signals of gravitational waves in narrow-band data of a detector. Our search is based on a statistic, commonly called the $\mathcal{F}$-statistic, derived from the maximum-likelihood principle in Paper I of this series. We briefly review the response of a ground-based detector to the gravitational-wave signal from a rotating neuron star and the derivation of the $\mathcal{F}$-statistic. We present several algorithms to calculate efficiently this statistic. In particular our algorithms are such that one can take advantage of the speed of fast Fourier transform in calculation of the $\mathcal{F}$-statistic. We construct a grid in the parameter space such that the nodes of the grid coincide with the Fourier frequencies. We present interpolation methods that approximately convert the two integrals in the $\mathcal{F}$-statistic into Fourier transforms so that the fast Fourier transform algorithm can be applied in their evaluation. We have implemented our methods and algorithms into computer codes and we present results of the Monte Carlo simulations performed to test these codes.

A simple extension of the standard model providing a TeV-scale seesaw mechanism is presented. Beside the standard model particles and right-handed Majorana neutrinos, the model contains a singly charged scalar, an extra Higgs doublet, and three vectorlike singly charged fermions. In our model, Dirac neutrino mass matrix raises only at the loop level. Small but nonzero Majorana neutrino masses come from integrating out heavy Majorana neutrinos, which can be at the TeV-scale. The phenomenologies of the model are investigated, including scalar mass spectrum, neutrino masses and mixings, lepton flavor violations, heavy neutrino magnetic moments as well as possible collider signatures of the model at the LHC.