We study the ability of weak-lensing surveys to detect galaxy clusters and constrain cosmological parameters, in particular, the equation of state of dark energy. There are two major sources of noise for weak-lensing cluster measurements: the “shape noise” from the intrinsic ellipticities of galaxies; and the large scale projection noise. We produce a filter for the shear field which optimizes the signal-to-noise of shape-noise-dominated shear measurements. Our Fisher-matrix analysis of this projected-mass observable makes use of the shape of this mass function, and takes into account the Poisson variance, sample variance, shape noise, and projected-mass noise, and also the fact that the conversion of the shear signal into mass is cosmology-dependent. The Fisher analysis is applied to both a nominal $15000{\mathrm{deg}}^2$ ground-based survey and a $1000{\mathrm{deg}}^2$ space-based survey. Assuming a detection threshold of $S/N=5$, we find both experiments detect $\approx 20\hspace{0.17em}000$ clusters, and yield $1\mathrm{\text{−}}\sigma$ constraints of $\Delta w_0\approx 0.07$, $\Delta w_a\approx 0.20$ when combined with cosmic microwave background data (for flat universe). The projection noise exceeds the shape noise only for clusters at $z\lesssim 0.1$ and has little effect on the derived dark-energy constraints. Sample variance does not significantly affect either survey. Finally, we note that all these results are extremely sensitive to the noise levels and detection thresholds that we impose. They can be significantly improved if we combine ground and space surveys as independent experiments and add their corresponding Fisher matrices.

The recent WMAP3 results have placed measurements of the spectral index $n_{\mathrm{S}}$ in an interesting position. While parameter estimation techniques indicate that the Harrison–Zel’dovich spectrum $n_{\mathrm{S}}=1$ is strongly excluded (in the absence of tensor perturbations), Bayesian model selection techniques reveal that the case against $n_{\mathrm{S}}=1$ is not yet conclusive. In this paper, we forecast the ability of the Planck satellite mission to use Bayesian model selection to convincingly exclude (or favor) the Harrison–Zel’dovich model.

We present a Bayesian model selection analysis of WMAP3 data using our code CosmoNest. We focus on the density perturbation spectral index $n_{\mathrm{S}}$ and the tensor-to-scalar ratio $r$, which define the plane of slow-roll inflationary models. We find that while the Bayesian evidence supports the conclusion that $n_{\mathrm{S}}\ne 1$, the data are not yet powerful enough to do so at a strong or decisive level. If tensors are assumed absent, the current odds are approximately 8 to 1 in favor of $n_{\mathrm{S}}\ne 1$ under our assumptions, when WMAP3 data is used together with external data sets. WMAP3 data on its own is unable to distinguish between the two models. Further, inclusion of $r$ as a parameter weakens the conclusion against the Harrison–Zel’dovich case ($n_{\mathrm{S}}=1$, $r=0$), albeit in a prior-dependent way. In appendices we describe the CosmoNest code in detail, noting its ability to supply posterior samples as well as to accurately compute the Bayesian evidence. We make a first public release of CosmoNest, now available at www.cosmonest.org.

We consider the ultrahigh energy cosmic ray (UHECR) spectrum as measured by the Pierre Auger Observatory. Top-down models for the origin of UHECRs predict an increasing photon component at energies above about ${10}^{19.7}\mathrm{eV}$. Here we present a simple prescription to compare the Auger data with a prediction assuming a pure proton component or a prediction assuming a changing primary component appropriate for a top-down model. We find that the UHECR spectrum predicted in top-down models is a good fit to the Auger data. Eventually, Auger will measure a composition-independent spectrum and will be capable of either confirming or excluding the quantity of photons predicted in top-down models.

We compute the energy spectrum of low-lying gluonic excitations in the presence of static quark-antiquark sources using Coulomb gauge and the quasiparticle representation. Within the valence sector of the Fock space we reproduce both, the overall normalization and the ordering of the spin-parity multiplets. We discus how the interactions induced by the nonabelian Coulomb kernel are central in to fine structure of the spectrum.

We derive the contributions to the quantum transport equations for electroweak baryogenesis due to decays and inverse decays induced by triscalar and Yukawa interactions. In the minimal supersymmetric standard model (MSSM), these contributions give rise to couplings between Higgs and fermion supermultiplet densities, thereby communicating the effects of $CP$-violation in the Higgs sector to the baryon sector. We show that the decay and inverse decay-induced contributions that arise at zeroth order in the strong coupling, ${\alpha }_s$, can be substantially larger than the $\mathcal{O}({\alpha }_s)$ terms that are generated by scattering processes and that are usually assumed to dominate. We revisit the often-used approximation of fast Yukawa-induced processes and show that for realistic parameter choices it is not justified. We solve the resulting quantum transport equations numerically with special attention to the impact of Yukawa rates and study the dependence of the baryon-to-entropy ratio $Y_B$ on MSSM parameters.

The mixing-induced $CP$ asymmetries in $B\to K^{*}\gamma \to K_S{\pi }^0\gamma$ and $B\to K^{*}\gamma \to K_L{\pi }^0\gamma$ are expected to be small within the standard model. So they are among the most promising decay modes to test the standard model. In this paper, we compute the mixing-induced $CP$ asymmetries in these decay modes, within the framework of the standard model, using perturbative QCD, and our conclusion is $S_{K_S{\pi }^0\gamma }=-S_{K_L{\pi }^0\gamma }=-(3.5\pm 1.7)\times {10}^{-2}$.

We develop a manifestly Lorentz covariant chiral quark model for the study of baryons as bound states of constituent quarks dressed by a cloud of pseudoscalar mesons. The approach is based on a nonlinear chirally symmetric Lagrangian, which involves effective degrees of freedom—constituent quarks and the chiral (pseudoscalar meson) fields. In a first step, this Lagrangian can be used to perform a dressing of the constituent quarks by a cloud of light pseudoscalar mesons and other heavy states using the calculational technique of infrared dimensional regularization of loop diagrams. We calculate the dressed transition operators with a proper chiral expansion which are relevant for the interaction of quarks with external fields in the presence of a virtual meson cloud. In a second step, these dressed operators are used to calculate baryon matrix elements. Applications are worked out for the masses of the baryon octet, the meson-nucleon sigma terms, the magnetic moments of the baryon octet, the nucleon charge radii, the strong vector-meson-nucleon couplings, and the full momentum dependence of the electromagnetic form factors of the nucleon.

We analyze the exclusive pseudoscalar $D_{[s]}^{+}{D}_{[s]}^{-}$ pair production in $e^{+}{e}^{-}$ annihilations at $\sqrt{s}=10.6\mathrm{GeV}$ using a nonfactorized PQCD with the light-front wave function that goes beyond the peaking approximation. We compare our nonfactorized analysis with the usual factorized analysis based on the peaking approximation in the calculation of the cross section for the heavy meson pair production. We also discuss the higher helicity contribution to the cross section. Our analysis provides a constraint on the size of quark transverse momentum inside the $D$ meson from the recent Belle data, ${\sigma }_{\exp }(e^{+}{e}^{-}\to D^{+}{D}^{-})<0.04[\mathrm{pb}]$.

Using a path integral approach we rederive a recently found representation of the Casimir energy for a sphere and a cylinder in front of a plane and derive the first correction to the proximity force theorem.

Previous studies concerning the interaction of branes and black holes suggested that a small black hole intersecting a brane may escape via a mechanism of reconnection. Here we consider this problem by studying the interaction of a small black hole and a domain wall composed of a scalar field and simulate the evolution of this system when the black hole acquires an initial recoil velocity. We test and confirm previous results, however, unlike the cases previously studied, in the more general set-up considered here, we are able to follow the evolution of the system also during the separation, and completely illustrate how the escape of the black hole takes place.

The idea of quantum relativity as a generalized, or rather deformed, version of Einstein (special) relativity has been taking shape in recent years. Following the perspective of deformations, while staying within the framework of Lie algebra, we implement explicitly a simple linear realization of the relativity symmetry, and explore systematically the resulting physical interpretations. Some suggestions we make may sound radical, but are arguably natural within the context of our formulation. Our work may provide a new perspective on the subject matter, complementary to the previous approach(es), and may lead to a better understanding of the physics.

We present a new method for the calculation of black hole perturbations induced by extended sources in which the solution of the nonlinear hydrodynamics equations is coupled to a perturbative method based on Regge-Wheeler/Zerilli and Bardeen-Press-Teukolsky equations when these are solved in the frequency domain. In contrast to alternative methods in the time domain which may be unstable for rotating black hole spacetimes, this approach is expected to be stable as long as an accurate evolution of the matter sources is possible. Hence, it could be used under generic conditions and also with sources coming from three-dimensional numerical relativity codes. As an application of this method we compute the gravitational radiation from an oscillating high-density torus orbiting around a Schwarzschild black hole and show that our method is remarkably accurate, capturing both the basic quadrupolar emission of the torus and the excited emission of the black hole.

The uniqueness theorem for a static charged higher dimensional black hole containing an asymptotically flat spacelike hypersurface with compact interior and with both degenerate and nondegenerate components of event horizon is proposed. By studies of the near-horizon geometry of degenerate horizons, one was able to eliminate the previous restriction concerning the inequality fulfilled by the charges of the adequate components of the aforementioned horizons.

In this work we propose use of infinite impulse response adaptive line enhancer (IIR ALE) filters for detection of gravitational waves from coalescing binaries. We extend our previous work and define an adaptive matched filter structure. Filter performance is analyzed in terms of the tracking capability and determination of filter parameters. Furthermore, following the Neyman-Pearson strategy, receiver operating characteristics are derived, with closedform expressions for detection threshold, false alarm, and detection probability. Extensive tests demonstrate the effectiveness of adaptive filters both in terms of small computational cost and robustness.

The doublet-triplet splitting problem can be simply solved in product-group GUT models, using a global symmetry that distinguishes the doublets from the triplets. Apart from giving the required mass hierarchy, this “triplet symmetry” can also forbid some of the triplet couplings to matter. We point out that, since this symmetry is typically generation-dependent, it gives rise to nontrivial flavor structure. Furthermore, because flavor symmetries cannot be exact, the triplet-matter couplings are not forbidden then but only suppressed. We construct models in which the triplet symmetry gives acceptable proton decay rate and fermion masses. In some of the models, the prediction $m_b\sim m_{\tau }$ is retained, while the similar relation for the first generation is corrected. Finally, all this can be accomplished with triplets somewhat below the GUT scale, supplying the right correction for the standard model gauge couplings to unify precisely.

Previous extrapolations of lattice QCD results for the nucleon mass to the physically relevant region of small quark masses, using chiral effective field theory, are extended and expanded in several directions. A detailed error analysis is performed. An approach with explicit $\Delta (1232)$ degrees of freedom is compared to a calculation with only pion and nucleon degrees of freedom. The role of the $\Delta (1232)$ for the low-energy constants of the latter theory is elucidated. The consistency with the chiral perturbation theory analysis of pion-nucleon scattering data is examined. It is demonstrated that this consistency can indeed be achieved if the $\Delta (1232)$ dominance of the $P$-wave pion-nucleon low-energy constant $c_3$ is accounted for. Introduction of the $\Delta (1232)$ as an explicit propagating degree of freedom is not crucial in order to describe the quark-mass dependence of the nucleon mass, in contrast to the situation with spin observables of the nucleon. The dependence on finite lattice volume is shown to yield valuable additional constraints. What emerges is a consistent and stable extrapolation scheme for pion masses below 0.6 GeV.

By employing the multilevel algorithm in numerical Monte Carlo simulations, we evaluate the static potential in four dimensional $SU(2)$ lattice gauge theory with no dynamical fermions, for static sources in the $j=\frac{1}{2},1,\frac{3}{2}$ representations. We find data supporting the Casimir scaling hypothesis. With the same technique we show that the ratio of the logarithm of Wilson loops in the $j=2$ and $j=\frac{1}{2}$ representations, as a function of the area of the loops, also satisfies Casimir scaling.

We consider the phase diagram of two-flavor quark matter under neutron star constraints for two nonlocal, covariant quark models within the mean-field approximation. In the first case (Model I) the nonlocality arises from the regularization procedure, motivated by the instanton liquid model, whereas in the second one (Model II) a separable approximation of the one-gluon exchange interaction is applied. We find that Model II predicts a larger quark mass gap and a chiral symmetry breaking (CSB) phase transition line which extends 15–20% further into the phase diagram spanned by temperature ($T$) and chemical potential ($\mu$). The corresponding critical temperature at $\mu =0$, $T_c(0)\simeq 140\mathrm{MeV}$, is in better accordance to recent lattice QCD results than the prediction of the standard local NJL model, which exceeds 200 MeV. For both Model I and Model II we have considered various coupling strengths in the scalar diquark channel, showing that different low-temperature quark matter phases can occur at intermediate densities: a normal quark matter (NQM) phase, a two-flavor superconducting (2SC) quark matter phase and a mixed 2SC-NQM phase. Although in most cases there is also a gapless 2SC phase, this occurs in general in a small region at nonzero temperatures, thus its effect should be negligible for compact star applications.

Relations between differential cross section for inelastic scattering of electrons on hadrons and hadron form factors (sum rules) are derived on the basis of analytical properties of heavy photon forward Compton scattering on hadrons. Sum rules relating the slope of form factors at zero momentum transfer and anomalous magnetic moments of hadrons with some integrals on photoproduction on a hadron are obtained as well. The convergency of these integrals is provided by the difference of individual sum rules for different hadrons. The universal interaction of the Pomeron with nucleons is assumed. We derive the explicit formulas for the processes of electroproduction on proton and light isobar nuclei. Sudakov’s parametrization of momenta for peripheral kinematics, relevant here, is used. The light-cone form of differential cross sections is also discussed. The accuracy of sum rules estimated in frames of pointlike hadrons and it is shown to be at the level of precision achievable by experiments. Suggestions and predictions for future experiments are also given.