We study the effect of peculiar motion in weak gravitational lensing. We derive a fully relativistic formula for the cosmic shear and the convergence in a perturbed Friedmann universe. We find a new contribution related to galaxies’ peculiar velocities. This contribution does not affect cosmic shear in a measurable way, since it is of second order in the velocity. However, its effect on the convergence (and consequently on the magnification, which is a measurable quantity) is important, especially for redshifts $z\le 1$. As a consequence, peculiar motion modifies also the relation between the shear and the convergence.

The growth rate of matter perturbation and the expansion rate of the Universe can be used to distinguish modified gravity and dark energy models in explaining the cosmic acceleration. The growth rate is parametrized by the growth index $\gamma$. We discuss the dependence of $\gamma$ on the matter energy density $\Omega$ and its current value ${\Omega }_0$ for a more accurate approximation of the growth factor. The observational data, including the data of the growth rate, are used to fit different models. The data strongly disfavor the Dvali-Gabadadze-Porrati model. For the dark energy model with a constant equation of state, we find that ${\Omega }_0=0.27\pm 0.02$ and $w=-0.97\pm 0.09$. For the $\Lambda \mathrm{CDM}$ model, we find that $\gamma ={0.64}_{-0.15}^{+0.17}$. For the Dvali-Gabadadze-Porrati model, we find that $\gamma ={0.55}_{-0.13}^{+0.14}$.

We investigate the thermodynamic and transport properties of the real scalar field theory at weak as well as strong couplings in the Hartree approximation of the Cornwall-Jackiw-Tomboulis formalism. To our surprise, we find that near phase transition all the thermodynamic and transport properties of the simplest real scalar model at certain strong coupling agree well with the lattice results of the complex QCD system. We also demonstrate that the system near phase transition is nonconformal and behaves as a nonperfect fluid.

Experiments at Jefferson Laboratory, MIT-Bates, LEGS, Mainz, Bonn, GRAAL, and Spring-8 offer new opportunities to understand in detail how nucleon resonance ($N^{*}$) properties emerge from the nonperturbative aspects of QCD. Preliminary data from CLAS Collaboration, which cover a large range of photon virtuality $Q^2$, show interesting behavior with respect to $Q^2$ dependence: in the region $Q^2\le 1.5{\mathrm{GeV}}^2$, both the transverse amplitude $A_{1/2}(Q^2)$ and the longitudinal amplitude $S_{1/2}(Q^2)$ decrease rapidly. In this work, we attempt to use first-principles lattice QCD (for the first time) to provide a model-independent study of the transition form factor between the nucleon and its first radially excited state.

We study the inclusive production of isolated prompt photons within the framework of the quasi-multi-Regge-kinematic approach, applying the quark Reggeization hypothesis. We describe accurately and without free parameters the transverse momentum and pseudorapidity spectra of prompt photons in the inclusive photoproduction at the HERA Collider. It is shown that the main mechanism of the inclusive prompt photon production in the $\gamma p$ collisions is the fusion of a Reggeized quark (antiquark) from the proton and a collinear antiquark (quark) from the photon into a photon, via the effective Reggeon-quark-gamma vertex. The fragmentation of the quark, which is produced via the gamma-Reggeon-quark and quark-Reggeon-quark vertices, into a photon is strongly suppressed by the isolation cone condition and it gives a significant contribution in the region of a large negative pseudorapidity only. At the stage of numerical calculations we use the Kimber-Martin-Ryskin prescription for unintegrated quark and gluon distribution functions, with the following collinear parton densities as input: Martin-Roberts-Stirling-Thorne for a proton and Glück-Reya-Vogt for a photon.

It is shown that intrinsic neutrino flavor violation invariably occurs when neutrinos are created within the standard model augmented by the known massive neutrinos, with mixing and nondegenerate masses. The effects are very small but much greater than the naive estimate $\Delta m^2/E_{\nu }^2$ or the branching ratio of indirect flavor violating processes such as $\mu \to e\gamma$ within the SM. We specifically calculate the probability (branching ratio) of pion decay processes with flavor violation, such as $\pi \to \mu {\overline{\nu }}_e$, showing nonzero results.

We present an investigation of the decays ${\overline{B}}^0\to {\Lambda }_c^{+}\overline{p}$ and $B^{-}\to {\Lambda }_c^{+}\overline{p}{\pi }^{-}$ based on $383\times {10}^6$ $\mathit{{\rm Y}}(4S)\to B\overline{B}$ decays recorded with the BABAR detector. We measure the branching fractions of these decays; their ratio is $\mathcal{B}(B^{-}\to {\Lambda }_c^{+}\overline{p}{\pi }^{-})/\mathcal{B}({\overline{B}}^0\to {\Lambda }_c^{+}\overline{p})=15.4\pm 1.8\pm 0.3$. The $B^{-}\to {\Lambda }_c^{+}\overline{p}{\pi }^{-}$ process exhibits an enhancement at the ${\Lambda }_c^{+}\overline{p}$ threshold and is a laboratory for searches for excited charm baryon states. We observe the resonant decays $B^{-}\to {\Sigma }_c(2455{)}^0\overline{p}$ and $B^{-}\to {\Sigma }_c(2800{)}^0\overline{p}$ but see no evidence for $B^{-}\to {\Sigma }_c(2520{)}^0\overline{p}$. This is the first observation of the decay $B^{-}\to {\Sigma }_c(2800{)}^0\overline{p}$; however, the mass of the observed excited ${\Sigma }_c^0$ state is $(2846\pm 8\pm 10)\mathrm{MeV}/c^2$, which is somewhat inconsistent with previous measurements. Finally, we examine the angular distribution of the $B^{-}\to {\Sigma }_c(2455{)}^0\overline{p}$ decays and measure the spin of the ${\Sigma }_c(2455{)}^0$ baryon to be $1/2$, as predicted by the quark model.

We provide a new derivation of the anisotropies of the cosmic microwave background (CMB), and find an exact expression that can be readily expanded perturbatively. Close attention is paid to gauge issues, with the motivation to examine the effect of super-Hubble modes on the CMB. We calculate a transfer function that encodes the behavior of the dipole, and examine its long-wavelength behavior. We show that contributions to the dipole from adiabatic super-Hubble modes are strongly suppressed, even in the presence of a cosmological constant, contrary to claims in the literature. We also introduce a naturally defined CMB monopole, which exhibits closely analogous long-wavelength behavior. We discuss the geometrical origin of this super-Hubble suppression, pointing out that it is a simple reflection of adiabaticity, and hence argue that it will occur regardless of the matter content.

In this article we study two problems that arise when using timing and amplitude estimates from a network of interferometers (IFOs) to evaluate the direction of an incident gravitational wave burst. First, we discuss an angular bias in the least squares timing-based approach that becomes increasingly relevant for moderate to low signal-to-noise ratios. We show how estimates of the arrival time uncertainties in each detector can be used to correct this bias. We also introduce a stand-alone parameter estimation algorithm that can improve the arrival time estimation and provide root-sum-squared strain amplitude ($h_{\mathrm{rss}}$) values for each site. In the second part of the paper we discuss how to resolve the directional ambiguity that arises from observations in three non co-located IFOs between the true source location and its mirror image across the plane containing the detectors. We introduce a new, exact relationship among the $h_{\mathrm{rss}}$ values at the three sites that, for sufficiently large signal amplitudes, determines the true source direction regardless of whether or not the signal is linearly polarized. Both the algorithm estimating arrival times, arrival time uncertainties, and $h_{\mathrm{rss}}$ values and the directional follow-up can be applied to any set of gravitational wave candidates observed in a network of three non co-located IFOs. As a case study we test the methods on simulated waveforms embedded in simulations of the noise of the LIGO and Virgo detectors at design sensitivity.

The radiative leptonic decay $B_c^{-}\to {\mu }^{-}{\overline{\nu }}_{\mu }\gamma$ is analyzed in its leading order in a relativistic independent quark model based on a confining potential in an equally mixed scalar-vector harmonic form. The branching ratio for this decay in the vanishing lepton mass limit is obtained as $\mathcal{B}r(B_c\to \mu {\nu }_{\mu }\gamma )=6.83\times {10}^{-5}$, which includes the contributions of the internal bremsstrahlung and structure-dependent diagrams at the level of the quark constituents. The contributions of the bremsstrahlung and the structure-dependent diagrams, as well as their additive interference parts, are compared and found to be of the same order of magnitude. Finally, the predicted photon energy spectrum is observed here to be almost symmetrical about the peak value of the photon energy at ${\tilde{E}}_{\gamma }\simeq \frac{M_{B_c}}{4}$, which may be quite accessible experimentally at LHC in near future.

We investigate spin-one color superconductivity of a single quark flavor using the Ginzburg–Landau theory. First we examine the classic analysis of Bailin and Love and show that by restricting to the so-called inert states, it misses the true ground state in a part of the phase diagram. This suggests the use of the more general, noninert states, in particular, within three-flavor quark matter where the color neutrality constraint imposes stress on the spin-one pairing and may disfavor the symmetric color-spin-locked state. In the second part of the paper we show that, in analogy to some ferromagnetic materials, lack of space-inversion symmetry leads to a new term in the Ginzburg–Landau functional, which favors a spatially nonuniform long-range ordering with a spiral structure. In color superconductors, this new parity-violating term is a tiny effect of weak-interaction physics. The modified phase diagram is determined and the corresponding ground states for all the phases constructed. At the end, we estimate the coefficient of the new term in the free energy functional, and discuss its relevance for the phenomenology of dense quark matter.

The complete analytical solutions of the geodesic equation of massive test particles in higher dimensional Schwarzschild, Schwarzschild–(anti)de Sitter, Reissner-Nordström and Reissner–Nordström–(anti)de Sitter spacetimes are presented. Using the Jacobi inversion problem restricted to the theta divisor the explicit solution is given in terms of Kleinian sigma functions. The derived orbits depend on the structure of the roots of the characteristic polynomials which depend on the particle’s energy and angular momentum, on the mass and the charge of the gravitational source, and the cosmological constant. We discuss the general structure of the orbits and show that due to the specific dimension-independent form of the angular momentum and the cosmological force a rich variety of orbits can emerge only in four and five dimensions. We present explicit analytical solutions for orbits up to 11 dimensions. A particular feature of Reissner-Nordström spacetimes is that bound and escape orbits traverse through different universes.

We generalize the reconstruction theorem of Stern, Sazdjian, and Fuchs based on the dispersion relations to the case of the ($2\to 2$) scattering of all the pseudoscalar octet mesons $(\pi ,K,\eta )$. We formulate it in a general way and include also a discussion of the assumptions of the theorem. It is used to obtain the amplitudes of all such processes in the isospin limit to the one-loop order (and can be straightforwardly extended to two loops) independently on the particular power-counting scheme of the chiral perturbation theory in question. The results in this general form are presented.

We found that spin-one new light particle exchanges are strongly bounded by high-energy and small momentum transfer $np$ elastic scattering data; the analogous bound for a scalar particle is considerably weaker, while for a pseudoscalar particle no bounds can be set. These bounds are compared with the bounds extracted from low-energy $n\mathrm{\text{−}}\mathrm{Pb}$ scattering experiments and from the bounds of ${\pi }^0$ and $K^{+}$ meson decays.

We discuss some cosmological implications of extensions of the standard model with hidden-sector scalars coupled to the Higgs boson. We put special emphasis on the conformal case, in which the electroweak symmetry is broken radiatively with a Higgs mass above the experimental limit. Our refined analysis of the electroweak phase transition in this kind of models strengthens the prediction of a strongly first-order phase transition as required by electroweak baryogenesis. We further study gravitational wave production and the possibility of low-scale inflation as well as a viable dark matter candidate.

Seesaw models with a slightly broken lepton number symmetry can explain small neutrino masses, and allow for low-scale leptogenesis. We make a thorough analysis of leptogenesis within the simplest model with two right-handed (RH) neutrinos (or with $N_3$ decoupled). We obtain a semianalytical formula for the final asymmetry in both supersymmetric and nonsupersymmetric cases with a simple dependence on each parameter. The low-energy parameters factorize from the high-energy ones, and the high-energy phase must be nonzero. The role of the low-energy phases is carefully studied. Moreover, we find that the breaking parameter in the Yukawa coupling matrix must be relatively large, ${ϵ}_h\gtrsim {10}^{-3}$ for normal and ${10}^{-2}$ for inverted hierarchy. Therefore, leptogenesis in our simple model is incompatible with RH neutrino signals at future colliders or sizable lepton-flavor violation. The other breaking parameter, ${ϵ}_M$, which appears in the RH neutrino mass matrix, can be much smaller, and actually needs to be so in order to have low-scale leptogenesis.

Thermal field theory is applied to particle production rates in inflationary models, leading to new results for catalyzed or two-stage decay, where massive fields act as decay channels for the production of light fields. A numerical investigation of the Boltzmann equation in an expanding universe shows that the particle distributions produced during small amplitude inflaton oscillations or even alongside slowly moving inflaton fields can thermalize.

We consider different renormalizable models of Lorentz invariance violation. We show that the limits on birefringence of the propagation of cosmic microwave background photons from the five year data of the Wilkinson Microwave Anisotropy Probe (WMAP) can be translated into a limit of Lorentz symmetry violation. The obtained limits on Lorentz invariance violation are stronger than other published limits. We also cast them in terms of limits on a birefringent effective photo mass and on a polarization dependence of the speed of light.

We consider a classical source, moving on the 4D boundary of a 5D anti-de Sitter space, that is coupled to quantum fields residing in the bulk. Bremsstrahlung-like radiation of the corresponding quanta is shown to occur and the S matrix is derived assuming that the source is sufficiently massive so that recoil effects are negligible. As an illustrative example, using the anti-de Sitter hard-wall model, we consider vector mesons coupled to a heavy nucleus that is moved around at high speed in an accelerator ring. The meson radiation rate is found to be finite but small. Much higher accelerations, such as when a pair of heavy ions suffer an ultra peripheral collision, cause substantial emission of various excited vector mesons. Predictions are made for the spectrum of this radiation. A comparison is made against existing photon-pomeron fusion calculations for the transverse momentum spectra of rho mesons. These have the same overall shape as the recently measured transverse momentum distributions at RHIC.

We use lattice QCD simulations, with MILC configurations (including vacuum polarization from $u$, $d$, and $s$ quarks), to update our previous determinations of the QCD coupling constant. Our new analysis uses results from 6 different lattice spacings and 12 different combinations of sea-quark masses to significantly reduce our previous errors. We also correct for finite-lattice-spacing errors in the scale setting, and for nonperturbative chiral corrections to the 22 short-distance quantities from which we extract the coupling. Our final result is ${\alpha }_V(7.5\mathrm{GeV},n_f=3)=0.2120(28)$, which is equivalent to ${\alpha }_{\overline{\mathrm{MS}}}(M_Z,n_f=5)=0.1183(8)$. We compare this with our previous result from Wilson loops, which differs by one standard deviation.