The standard post-Newtonian approximation to gravitational waveforms, called T-approximants, from nonspinning black hole binaries are known not to be sufficiently accurate close to the last stable orbit of the system. A new approximation, called P-approximants, is believed to improve the accuracy of the waveforms rendering them applicable up to the last stable orbit. In this study we apply P-approximants to the case of a test particle in equatorial orbit around a Kerr black hole parameterized by a spin-parameter $q$ that takes values between $-1$ and 1. In order to assess the performance of the two approximants we measure their effectualness (i.e., larger overlaps with the exact signal), and faithfulness (i.e., smaller biases while measuring the parameters of the signal) with the exact (numerical) waveforms. We find that in the case of prograde orbits, that is orbits whose angular momentum is in the same sense as the spin angular momentum of the black hole, T-approximant templates obtain an effectualness of $\sim 0.99$ for spins $q\lesssim 0.75$. For $0.75<q<0.95$, the effectualness drops to about 0.82. The P-approximants achieve effectualness of $>0.99$ for all spins up to $q=0.95$. The bias in the estimation of parameters is much lower in the case of P-approximants than T-approximants. We find that P-approximants are both effectual and faithful and should be more effective than T-approximants as a detection template family when $q>0$. For $q<0$ both T- and P-approximants perform equally well so that either of them could be used as a detection template family.

We show that charged particles decaying in the early Universe can induce a scale-dependent or running spectral index in the small-scale linear and nonlinear matter power spectrum and discuss examples of this effect in minimal supersymmetric models in which the lightest neutralino is a viable cold-dark-matter candidate. We find configurations in which the neutralino relic density is set by coannihilations with a long-lived stau and the late decay of staus partially suppresses the linear matter power spectrum. Nonlinear evolution on small scales then causes the modified linear power spectrum to evolve to a nonlinear power spectrum similar to (but different in detail) models parametrized by a constant running ${\alpha }_s=d{n}_s/d\mathrm{l}\mathrm{n}k$ by redshifts of 2 to 4. Thus, Lyman-$\alpha$ forest observations, which probe the matter power spectrum at these redshifts, might not discriminate between the two effects. However, a measurement of the angular power spectrum of primordial 21-cm radiation from redshift $z\approx 30–200$ might distinguish between this charged-decay model and a primordial running spectral index. The direct production of a long-lived charged particle at future colliders is a dramatic prediction of this model.

Based on the most recent data in charmless $B$ decays including the very recently reported large direct $CP$ violations, it is shown that the weak phase $\gamma$ can well be extracted without twofold ambiguity even only from two decay modes ${\pi }^{+}{\pi }^{-}$ and ${\pi }^{+}{K}^{-}$, and its value is remarkably consistent with the global standard model fit at a compatible accuracy. A fit to all the $\pi \pi ,\pi K$ data favor both large electroweak penguin and color-suppressed tree amplitude with large strong phases. It is demonstrated that the inclusion of $\mathrm{S}\mathrm{U}(3)$ symmetry breaking effects of strong phases and the inelastic rescattering effects can well improve the consistency of the data, while both effects may not be sufficient to arrive at a small electroweak penguin amplitude in the standard model. It is of interest to notice that large or small electroweak penguin amplitude becomes a testable prediction as they lead to significantly different predictions for the direct $CP$ violations for ${\pi }^0{\pi }^0$, ${\pi }^0{\overline{K}}^0$ modes. Clearly, precise measurements on charmless $B$ decays will provide a window for probing new physics.

The low-energy behavior of a recently proposed model for the massive analytic running coupling of QCD is studied. This running coupling has no unphysical singularities, and in the absence of masses displays infrared enhancement. The inclusion of the effects due to the mass of the lightest hadron is accomplished by employing the dispersion relation for the Adler $D$ function. The presence of the nonvanishing pion mass tames the aforementioned enhancement, giving rise to a finite value for the running coupling at the origin. In addition, the effective charge acquires a plateaulike behavior in the low-energy region of the timelike domain. This plateau is found to be in agreement with a number of phenomenological models for the strong running coupling. The developed invariant charge is applied in the processing of experimental data on the inclusive $\tau$ lepton decay. The effects due to the pion mass play an essential role here as well, affecting the value of the QCD scale parameter $\Lambda$ extracted from these data. Finally, the massive analytic running coupling is compared with the effective coupling arising from the study of Schwinger-Dyson equations, whose infrared finiteness is due to a dynamically generated gluon mass. A qualitative picture of the possible impact of the former coupling on the chiral symmetry breaking is presented.

We analyze the behavior of standard model matter propagating in a slice of ${\mathrm{A}\mathrm{d}\mathrm{S}}_5$ in the presence of infrared-brane kinetic terms. Brane kinetic terms are naturally generated through radiative corrections and can also be present at tree level. The effect of the brane kinetic terms is to expel the heavy Kaluza-Klein (KK) modes from the infrared brane, and hence to reduce their coupling to the localized Higgs field. In a previous work we showed that sizable gauge kinetic terms can allow KK mode masses as low as a few TeV, compatible with present precision measurements. We study here the effect of fermion brane kinetic terms and show that they ameliorate the behavior of the theory for third generation fermions localized away from the infrared brane, reduce the contribution of the third generation quarks to the oblique correction parameters and maintain a good fit to the precision electroweak data for values of the KK masses of the order of the weak scale.

Some versions of the electroweak $\mathrm{S}\mathrm{U}(3{)}_L\otimes \mathrm{U}(1{)}_X$ models cannot be treated within perturbation theory at energies of few TeV. An extended version for these models is proposed which is perturbative even at TeV scale posing no threatening inconsistency for test at future colliders. The extension presented here needs the addition of three octets of vector leptons, which leave three new leptonic isotriplets in the $\mathrm{S}\mathrm{U}(2{)}_L\otimes \mathrm{U}(1{)}_Y$ subgroup. With this representation content the running of the electroweak mixing angle, ${\theta }_W(\mu )$, is such that ${sin}^2{\theta }_W(\mu )$ decreases with the increase of the energy scale $\mu$, when only the light states of the standard model group are considered. The neutral exotic gauge boson $Z^{\prime }$ marks then a new symmetry frontier.

If physics beyond the standard model is present in $B$ decays, experimental measurements seem to suggest that it principally affects those processes with significant $\overline{b}\to \overline{s}$ penguin amplitudes. It was recently argued that, in general, such new-physics (NP) effects can be parametrized in terms of a single NP amplitude ${\mathcal{A}}^q$ and phase ${\Phi }_q$, for $q=u,d,s,c$. In this paper, we show that the study of the decays $B_s^0(t)\to K^{+}{K}^{-}$ and $B_d^0(t)\to {\pi }^{+}{\pi }^{-}$ allows one to measure the NP parameters ${\mathcal{A}}^u$ and ${\Phi }_u$. We examine the implications for this method of the latest experimental results on these decays. If NP is found in $B_s^0(t)\to K^{+}{K}^{-}$, it can be partially identified through measurements of $B_s^0(t)\to K^0{\overline{K}}^0$.

A longitudinal double spin asymmetry for ${\pi }^0$ production has been measured by the PHENIX collaboration. The asymmetry is sensitive to the polarized gluon distribution and is indicated to be positive by theoretical predictions. We study a correlation between behavior of the asymmetry and polarized gluon distribution in neutral and charged pion production at RHIC.

We calculate the next-to-leading-order cross section for the inclusive production of $D^{*\pm }$ mesons in $p\overline{p}$ collisions as a function of the transverse momentum and the rapidity in two approaches using massive or massless charm quarks. For the inclusive cross section, we derive the massless limit from the massive theory. We find that this limit differs from the genuine massless version with $\overline{\mathrm{M}\mathrm{S}}$ (minimal-subtraction) factorization by finite corrections. By adjusting subtraction terms, we establish a massive theory with $\overline{\mathrm{M}\mathrm{S}}$ subtraction which approaches the massless theory with increasing transverse momentum. With these results and including the contributions due to the charm and anticharm content of the proton and antiproton, we calculate the inclusive $D^{*\pm }$ cross section in $p\overline{p}$ collisions using realistic evolved nonperturbative fragmentation functions and compare with recent data from the CDF Collaboration at the Fermilab Tevatron at center-of-mass energy $\sqrt{S}=1.96\mathrm{T}\mathrm{e}\mathrm{V}$. We find reasonable, though not perfect, agreement with the measured cross sections.

We discuss a scenario where at least part of the homogeneity on a brane world can be directly related to the hierarchy problem through warped space. We study the dynamics of an anti-D3-brane moving toward the infrared cutoff of a warped background. After a region described by the Dirac-Born-Infeld action, the self-energy of the anti-D3-brane becomes comparable to the strength of the background. Then the world-volume scale of the anti-D3-brane is no longer comoving with the background geometry. After it settles down in the infrared end, the world-volume inhomogeneity will appear, to a Poincaré observer, to be stretched by an exponentially large ratio. This ratio is close to that of the hierarchy problem between the gravitational and electroweak scales.

We compute bounce solutions describing false vacuum decay in a ${\Phi }^4$ model in two dimensions in the Hartree approximation, thus going beyond the usual one-loop corrections to the decay rate. We use zero energy mode functions of the fluctuation operator for the numerical computation of the functional determinant and the Green’s function. We thus avoid the necessity of discretizing the spectrum, as it is necessary when one uses numerical techniques based on eigenfunctions. Regularization is performed in analogy of standard perturbation theory; the renormalization of the Hartree approximation is based on the two-particle point-irreducible scheme. The iteration towards the self-consistent solution is found to converge for some range of the parameters. Within this range we find the corrections to the leading one-loop approximation to be relatively small, not exceeding 1 order of magnitude in the total transition rate.

All quantum gravity approaches lead to small modifications in the standard laws of physics which in most cases lead to violations of Lorentz invariance. One particular example is the extended standard model (SME). Here, a general phenomenological approach for extensions of the Maxwell equations is presented which turns out to be more general than the SME and which covers charge nonconservation (CNC), too. The new Lorentz invariance violating terms cannot be probed by optical experiments but need, instead, the exploration of the electromagnetic field created by a point charge or a magnetic dipole. Some scalar tensor theories and higher dimensional brane theories predict CNC in four dimensions and some models violating special relativity have been shown to be connected with CNC. Its relation to the Einstein Equivalence Principle has been discussed. Because of this upcoming interest, the experimental status of electric charge conservation is reviewed. Up to now there seem to exist no unique tests of charge conservation. CNC is related to the precession of polarization, to a modification of the $1/r$-Coulomb potential, and to a time dependence of the fine structure constant. This gives the opportunity to describe a dedicated search for CNC.

We investigate the stability of higher dimensional rotating black holes against scalar perturbations. In particular, we make a thorough numerical and analytical analysis of six dimensional black holes, not only in the low rotation regime but in the high rotation regime as well. Our results suggest that higher dimensional Kerr black holes are stable against scalar perturbations, even in the ultraspinning regime.

We show that duality transformations of linearized gravity in four dimensions, i.e., rotations of the linearized Riemann tensor and its dual into each other, can be extended to the dynamical fields of the theory so as to be symmetries of the action and not just symmetries of the equations of motion. Our approach relies on the introduction of two superpotentials, one for the spatial components of the spin-2 field and the other for their canonically conjugate momenta. These superpotentials are two-index, symmetric tensors. They can be taken to be the basic dynamical fields and appear locally in the action. They are simply rotated into each other under duality. In terms of the superpotentials, the canonical generator of duality rotations is found to have a Chern-Simons-like structure, as in the Maxwell case.

We study models of axi-dilaton gravity in space-time geometries with torsion. We discuss conformal rescaling rules in both Riemannian and non-Riemannian formulations. We give static, spherically symmetric solutions and examine their singularity behavior.

We investigate the thermal production of gravitinos in the context of the brane world cosmology. Since the expansion law is modified from the one in the standard cosmology, the Boltzmann equation for the gravitino production is altered. We find that the late-time gravitino abundance is proportional to the “transition temperature”, at which the modified expansion law in the brane world cosmology is connecting with the standard one, rather than the reheating temperature after inflation as in the standard cosmology. This means that, even though the reheating temperature is very high, we can avoid the overproduction of gravitinos by taking the transition temperature low enough. Therefore, the gravitino problem can be solved.

We wish to put forward an explanation for a peculiar cosmic ray event with energy $\Sigma E_{\gamma }\ge 2\times {10}^{15}$ eV detected in $1975$ by the balloon borne emulsion chamber experiment performed in the stratosphere, at the altitude $\ge 30$ km above sea level. For almost 30 years the event has been described as unusual, invoking new exotic mechanisms or models. In our opinion there is no need for an extraordinary explanation. Contrary to the widespread belief, the event gives us an example of “unrecognized standard physics”. At the same time this event revealed a variety of features which are of considerable interest for cosmic rays, nuclear physics, and astrophysics. Here we show that the observed family is most likely to be a result of a heavy nucleus interaction with an air nucleus. In this case a primary particle would originally have been in the energy region above “the knee” of the cosmic ray spectrum.

Little Higgs models have an enlarged global symmetry which makes the Higgs boson a pseudo-Goldstone boson. This symmetry typically contains spontaneously broken U(1) subgroups which provide light electroweak-singlet pseudoscalars. Unless such particles are absorbed as the longitudinal component of $Z^{\prime }$ states, they appear as pseudoscalars in the physical spectrum at the electroweak scale. We outline their significant impact on little Higgs phenomenology and analyze a few possible signatures at the LHC and other future colliders in detail. In particular, their presence significantly affects the physics of the new heavy quark states predicted in little Higgs models, and inclusive production at LHC may yield impressive diphoton resonances.

The neutralino-nucleon (${\tilde{\chi }}^0$-$N$) scattering is an important process for direct dark matter searches. In this paper we discuss one-loop contributions to the cross section in the winolike and Higgsino-like LSP cases. The neutralino-nucleon scattering mediated by the Higgs ${\tilde{\chi }}^0{\tilde{\chi }}^0$ and $Z{\tilde{\chi }}^0{\tilde{\chi }}^0$ couplings at tree level is suppressed by the gaugino-Higgsino mixing at tree-level when the neutralino is close to a weak eigenstate. The one-loop contribution to the cross section, generated by the gauge interaction, is not suppressed by any SUSY particle mass or mixing in the wino- and Higgsino-like LSP cases. It may significantly alter the total cross section when ${\sigma }_{{\tilde{\chi }}^{0}N}\sim {10}^{-45}{\mathrm{c}\mathrm{m}}^2$ or less.