I discuss an astrometric timing effect on data analysis of continuous gravitational waves from rapidly rotating isolated neutron stars. Special attention is directed to the possibility of determining their distances by measuring the curvature of the wave fronts. I predict that if continuous gravitational waves from an unknown neutron star with a stable rotation are detected around 1 kHz within $1/3\mathrm{yr}$ by initial LIGO detectors and the ellipticity parameter $ϵ$ is smaller than ${10}^{-6}$, the distance $r$ to the source can be estimated with relative error $\Delta r/r$ of $\sim 10\%$ by using the broadband configuration of advanced LIGO detectors over 3 years. By combining the observed amplitude of the waves with the estimated distance, information on the parameter $ϵ$ can be obtained purely through gravitational wave measurements.

We explore patterns of effective restoration of the chiral ${\mathrm{U}}_A(1)$ symmetry using an extended three-flavor Nambu-Jona-Lasinio model that incorporates explicitly the axial anomaly through the ’t Hooft interaction, and assuming that the coefficient of the anomaly term is temperature and density dependent. The special case of explicit breaking of chiral symmetry without ${\mathrm{U}}_A(1)$ anomaly is also considered, since this scenario can provide additional information allowing to understand the interplay between the ${\mathrm{U}}_A(1)$ anomaly and (spontaneous) chiral symmetry-breaking effects. The pseudoscalar and scalar sectors are analyzed in detail bearing in mind the identification of chiral partners and the study of its convergence. We also concentrate on the behavior of the mixing angles that give us relevant information on the issue under discussion. In the region of temperatures (densities) studied, we do not observe signs indicating a full restoration of $\mathrm{U}(3)\otimes \mathrm{U}(3)$ symmetry as, for instance, the degeneracy of both $a_0$ and $f_0$ mesons with the pion. As we work in a real world scenario ($m_u=m_d\ll m_s$), we only observe the return to symmetries of the classical QCD Lagrangian in the nonstrange sector.

A Higgs boson lighter than $2m_W$ that decays mostly into invisible channels (e.g., dark matter particles) is theoretically well-motivated. We study the prospects for discovery of such an invisible Higgs, $h_{\mathrm{inv}}$, at the LHC and the Tevatron in three production modes: (1) in association with a $Z$, (2) through weak boson fusion (WBF), and (3) accompanied by a jet. In the $Z+h_{\mathrm{inv}}$ channel, we show that the LHC can yield a discovery signal above $5\sigma$ with $10{\mathrm{fb}}^{-1}$ of integrated luminosity for a Higgs mass of 120 GeV. With $30{\mathrm{fb}}^{-1}$ the discovery reach extends up to a Higgs mass of 160 GeV. We also study the extraction of the $h_{\mathrm{inv}}$ mass from production cross sections at the LHC, and find that combining WBF and $Z+h_{\mathrm{inv}}$ allows a relatively model-independent determination of the $h_{\mathrm{inv}}$ mass with an uncertainty of 35–50 GeV (15–20 GeV) with $10(100){\mathrm{fb}}^{-1}$. At the Tevatron, a $3\sigma$ observation of a 120 GeV $h_{\mathrm{inv}}$ in any single channel is not possible with less than $12{\mathrm{fb}}^{-1}$ per detector. However, we show that combining the signal from WBF with the previously studied $Z+h_{\mathrm{inv}}$ channel allows a $3\sigma$ observation of $h_{\mathrm{inv}}$ with $7{\mathrm{fb}}^{-1}$ per detector. Because of overwhelming irreducible backgrounds, $h_{\mathrm{inv}}+j$ is not a useful search channel at either the Tevatron or the LHC, despite the larger production rate.

We illustrate for 4D $SU(2)$ and $U(1)$ lattice gauge theory that sampling with a biased Metropolis scheme is essentially equivalent to using the heat bath algorithm. Only, the biased Metropolis method can also be applied when an efficient heat bath algorithm does not exist. For the examples discussed the biased Metropolis algorithm is also better suited for parallelization than the heat bath algorithms.

It is shown that in ultrahigh-energy inelastic neutrino-nucleon(nucleus) scattering the cross sections for the boson-hadron(nucleus) reactions should exhibit geometric scaling on the single variable ${\tau }_A=Q^2/Q_{\mathrm{sat},\mathrm{A}}^2$. The dependence on energy and atomic number of the charged/neutral current cross sections are encoded in the saturation momentum $Q_{\mathrm{sat},\mathrm{A}}$. This fact allows an analytical computation of the neutrino scattering on nucleon/nucleus at high energies, providing a theoretical parameterization based on the scaling property.

The mass shift induced by one-loop quantum fluctuations on self-dual Abrikosov-Nielsen-Olesen (ANO) vortices is computed using heat kernel/generalized zeta function regularization methods. The quantum masses of superimposed multivortices with vorticity lower than five are given. The case of two separate vortices with a quantum of magnetic flux is also discussed.

We develop a formalism to characterize the shape and the redshift evolution of the dark energy potential. Our formalism makes use of quantities similar to the horizon-flow parameters in inflation and is general enough that can deal with multiscalar quintessence scenarios, exotic matter components, and higher-order curvature corrections to General Relativity. We show how the shape of the dark energy potential can be recovered nonparametrically using this formalism and we present approximations analogous to the ones relevant to slow-roll inflation. Since presently available data do not allow a nonparametric and exact reconstruction of the potential, we consider a general parametric description. This reconstruction can also be used in other approaches followed in the literature (e.g., the reconstruction of the redshift evolution of the dark energy equation of state $w(z)$). Using observations of passively evolving galaxies and supernova data we derive constraints on the dark energy potential shape in the redshift range $0.1<z<1.8$. Our findings show that at the $1\sigma$ level the potential is consistent with being constant, although at the same level of confidence variations cannot be excluded with current data. We forecast constraints achievable with future data from the Atacama Cosmology Telescope.

We study classical dynamics of a probe $\mathrm{D}p$-brane moving in a background sourced by a stack of $\mathrm{D}p$-branes. In this context the physics is similar to that of the effective action for open-string tachyon condensation, but with a power-law runaway potential. We show that small inhomogeneous ripples of the probe brane embedding grow with time, leading to folding of the brane as it moves. We give a full nonlinear analytical treatment of inhomogeneous brane dynamics, suitable for the Dirac-Born-Infeld$\mathrm{\text{+Wess-Zumino}}$Wess-Zumino theory with arbitrary runaway potential, in the case where the source branes are Bogomol’nyi-Prasad-Sommerfield (BPS). In the near-horizon geometry, the inhomogeneous brane motion has a dual description in terms of free streaming of massive relativistic test particles originating from the initial hypersurface of the probe brane. We discuss limitations of the effective action description around loci of self-crossing of the probe brane (caustics). We also discuss the effect of brane folding in application to the theory of cosmological fluctuations in string theory inflation.

Measurements of the evolution with redshift of the number density of massive galaxy clusters are used to constrain the energy density of massive neutrinos and so the sum of neutrino masses $\sum _{}^{}{m}_{\nu }$. We consider a spatially flat cosmological model with cosmological constant, cold dark matter, baryonic matter, and massive neutrinos. Accounting for the uncertainties in the measurements of the relevant cosmological parameters we obtain a limit of $\sum _{}^{}{m}_{\nu }<2.4\mathrm{eV}$ (95% C.L.).

We compute the leading-order collisional energy loss of a heavy quark propagating through a quark-gluon plasma in which the quark and gluon distributions are anisotropic in momentum space. Following the calculation outlined for QED in an earlier work we indicate the differences encountered in QCD and their effect on the collisional energy loss results. For a 20 GeV bottom quark we show that momentum-space anisotropies can result in the collisional heavy-quark energy loss varying with the angle of propagation by up to 50%. For low velocity quarks we show that anisotropies result in energy gain instead of energy loss with the energy gain focused in such a way as to accelerate particles along the anisotropy direction thereby reducing the momentum-space anisotropy. A relation between the origin of this negative energy loss and the presence of plasma instabilities in the system is pointed out.

We use the overlapping grids method to construct a fourth order accurate discretization of a first order reduction of the Klein-Gordon scalar field equation on a boosted spinning black hole background in axisymmetry. This method allows us to use a spherical outer boundary and excise the singularity from the domain with a spheroidal inner boundary which is moving with respect to the main grid. We discuss the use of higher order accurate energy conserving schemes to handle the axis of symmetry and compare it with a simpler technique based on regularity conditions. We also compare the single grid long-term stability property of this formulation of the wave equation with that of a different first order reduction.

The standard geometrodynamics is transformed into a theory of conformal geometrodynamics by extending the Arnowitt-Deser-Misner (ADM) phase space for canonical general relativity to that consisting of York’s mean exterior curvature time, conformal three-metric and their momenta. Accordingly, an additional constraint is introduced, called the conformal constraint. In terms of the new canonical variables, a diffeomorphism constraint is derived from the original momentum constraint. The Hamiltonian constraint then takes a new form. It turns out to be the sum of an expression that previously appeared in the literature and extra terms quadratic in the conformal constraint. The complete set of the conformal, diffeomorphism and Hamiltonian constraints are shown to be of first class through the explicit construction of their Poisson brackets. The extended algebra of constraints has as subalgebras the Dirac algebra for the deformations and Lie algebra for the conformorphism transformations of the spatial hypersurface. This is followed by a discussion of potential implications of the presented theory on the Dirac constraint quantization of general relativity. An argument is made to support the use of the York time in formulating the unitary functional evolution of quantum gravity. Finally, the prospect of future work is briefly outlined.

We obtain an effective theory for the radion dynamics of the two-brane Randall-Sundrum model, correct to all orders in brane velocity in the limit of close separation, which is of interest for studying brane collisions and early universe cosmology. Obtained via a recursive solution of the bulk equation of motion, the resulting theory represents a simple extension of the corresponding low-energy effective theory to the high-energy regime. The four-dimensional low-energy theory is indeed not valid when corrections at second order in velocity are considered. This extension has the remarkable property of including only second derivatives and powers of first order derivatives. This important feature makes the theory particularly easy to solve. We then extend the theory by introducing a potential and detuning the branes.

We investigate the possibility of constraining dark energy with the integrated Sachs-Wolfe effect recently detected by cross-correlating the Wilkinson Microwave Anisotropy Probe maps with several large scale structure surveys. In agreement with previous works, we found that, under the assumption of a flat universe, the integrated Sachs-Wolfe signal is a promising tool for constraining dark energy. Current available data put weak limits on a constant dark energy equation of state $w$. We also find no constraints on the dark energy sound speed $c_e^2$. For quintessencelike dark energy ($c_e^2=1$) we find $w<-0.53$, while tighter bounds are possible only if the dark energy is “clustered” ($c_e^2=0$), in such a case $-1.94<w<-0.63$ at $2\sigma$. Better measurements of the cosmic microwave background-large scale structure correlation will be possible with the next generation of deep redshift surveys. This will provide independent constraints on the dark energy which are alternative to those usually inferred from cosmic microwave background and SN-Ia data.

Searches for the standard model Higgs boson by the four LEP experiments found excess events in two mass ranges: a $2.3\sigma$ excess around 98 GeV, and a $1.7\sigma$ excess around 115 GeV. The latter has been discussed widely in the literature, but the former has attracted relatively little attention so far. In this paper I explore the possibility of explaining the excess near 98 GeV through production of the lighter $CP$-even Higgs boson in the minimal supersymmetric standard model (MSSM). It is shown that this allows to simultaneously explain the excess near 115 GeV through the production of the heavier $CP$-even MSSM Higgs boson. The resulting light Higgs sector offers opportunities for charged Higgs boson searches at the Tevatron and LHC. Neutral Higgs boson searches at the LHC in the di-muon channel are also promising. However, conclusive tests of this scenario may have to wait for the construction of a linear $e^{+}{e}^{-}$ collider.

We present a through discussion of motivations for and phenomenological issues in supersymmetric models with minimal matter content and nonholomorphic soft-breaking terms. Using the unification of the gauge couplings and assuming SUSY is broken with nonstandard soft terms, we provide semianalytic solutions of the RGEs for low and high choices of $\tan \beta$ which can be used to study the phenomenology in detail. We also present a generic form of RGIs in mSUGRA framework which can be used to derive new relations in addition to those existing in the literature. Our results are mostly presented with respect to the conventional minimal supersymmetric model for ease of comparison.

We analyze the $B\to (J/\psi ,{\chi }_{c0},{\chi }_{c1},{\eta }_c)K^{(*)}$ decays, which have small or even vanishing branching ratios in naive factorization assumption (FA). We calculate nonfactorizable corrections to FA in the perturbative QCD approach based on $k_T$ factorization theorem. The charmonium distribution amplitudes are inferred from the nonrelativistic heavy quarkonium wave functions. It is found that the nonfactorizable contributions enhance the branching ratios and generate the relative phases among helicity amplitudes of the above modes. Most of the observed branching ratios, polarization fractions, and relative phases, except those of $B\to {\eta }_{c}K$, are explained. Our predictions for the $B\to ({\chi }_{c0},{\chi }_{c1},{\eta }_c)K^{*}$ decays can be compared with future data.