One proposed solution of the moduli problem of string cosmology requires that the moduli are quite heavy, their decays reheating the Universe to temperatures above the scale of nucleosynthesis. In many of these scenarios, the moduli are approximately supersymmetric; it is then crucial that the decays to gravitinos are helicity suppressed. In this paper, we discuss situations where these decays are, and are not, suppressed. We also comment on a possible gravitino problem from inflaton decay.

Scattering of cosmic microwave background (CMB) radiation in galaxy clusters induces a polarization signal proportional to the CMB quadrupole anisotropy at the cluster’s location and lookback time. A survey of such remote quadrupole measurements provides information about large-scale cosmological perturbations. This paper presents a formalism for calculating the correlation function of remote quadrupole measurements in spherical harmonic space. The number of independent modes probed by both single-redshift and volume-limited surveys is presented, along with the length scales probed by these modes. In a remote quadrupole survey sparsely covering a large area of sky, the largest-scale modes probe the same-length scales as the quadrupole but with much narrower Fourier-space window functions. The largest-scale modes are significantly correlated with the local CMB, but even when this correlation is projected out the largest remaining modes probe gigaparsec scales (comparable to the CMB at $l=2\mathrm{\text{−}}10$) with narrow window functions. These modes may provide insight into the possible anomalies in the large-scale CMB anisotropy. At fixed redshift, the data from such a survey form an $E$-type spin-2 field on the sphere to a good approximation; the near absence of $B$ modes will provide a valuable check on systematic errors. A survey of only a few low-redshift clusters allows an independent reconstruction of the five coefficients of the local CMB quadrupole, providing a test for contamination in the Wilkinson Microwave Anisotropy Probe quadrupole. The formalism presented here is also useful for analyzing smaller-scale surveys to probe the late integrated Sachs-Wolfe effect and hence the properties of dark energy.

Using the solitonic solution-generating technique, we rederived the one-rotational five-dimensional black ring solution found by Emparan and Reall. The seed solution is not the Minkowski metric, which is the seed of the $S^2$-rotating black ring. The obtained solution has more parameters than Emparan and Reall’s $S^1$-rotating black ring. We found the conditions of parameters to reduce the solution to the $S^1$-rotating black ring. In addition, we examined the relation between the expressions of the metric in the prolate-spheroidal coordinates and in the canonical coordinates.

We analyze the exclusive rare $B\to K^{(*)}{\ell }^{+}{\ell }^{-}$, $B\to K^{(*)}\nu \overline{\nu }$, and $B\to K^{*}\gamma$ decays in the Applequist-Cheng-Dobrescu model, which is an extension of the standard model in presence of universal extra dimensions. In particular, we consider the case of a single universal extra dimension. We study how spectra, branching fractions and asymmetries depend on the compactification parameter $1/R$, and whether the hadronic uncertainty due to the form factors obscures or not such a dependence. We find that, using present data, it is possible in many cases to put a sensible lower bound to $1/R$, the most stringent one coming from $B\to K^{*}\gamma$. We also study how improved experimental data can be used to establish stronger constraints to this model.

We show that some models with $SU(3{)}_C\otimes SU(3{)}_L\otimes U(1{)}_X$ gauge symmetry can be realized at the electroweak scale and that this is a consequence of an approximate global $SU(2{)}_{L+R}$ symmetry. This symmetry implies a condition among the vacuum expectation value of one of the neutral Higgs scalars, the $U(1{)}_X$’s coupling constant, $g_X$, the sine of the weak mixing angle $\sin {\theta }_W$, and the mass of the $W$ boson, $M_W$. In the limit in which this symmetry is valid it avoids the tree level mixing of the $Z$ boson of the standard model with the extra $Z^{\prime }$ boson. We have verified that the oblique $T$ parameter is within the allowed range indicating that the radiative corrections that induce such a mixing at the 1-loop level are small. We also show that a $SU(3{)}_{L+R}$ custodial symmetry implies that in some of the models we have to include sterile (singlets of the 3-3-1 symmetry) right-handed neutrinos with Majorana masses, since the seesaw mechanism is mandatory to obtain light active neutrinos. Moreover, the approximate $SU(2{)}_{L+R}\subset SU(3{)}_{L+R}$ symmetry implies that the extra nonstandard particles of these 3-3-1 models can be considerably lighter than it had been thought before so that new physics can be really just around the corner.

From a sample of $232\times {10}^6$ $\mathit{{\rm Y}}(4S)\to B\overline{B}$ events collected with the BABAR detector at the PEP-II $B$ Factory in 1999–2004, we measure the $B^{-}\to D^0{K}^{*-}(892)$ decay branching fraction using events where the $K^{*-}$ is reconstructed in the $K_S^0{\pi }^{-}$ mode and the $D^0$ in the $K^{-}{\pi }^{+}$, $K^{-}{\pi }^{+}{\pi }^0$, and $K^{-}{\pi }^{+}{\pi }^{+}{\pi }^{-}$ channels: $\mathcal{B}(B^{-}\to D^0{K}^{*-}(892))=(5.29\pm 0.30(\mathrm{stat})\pm 0.34(\mathrm{syst}))\times {10}^{-4}.$

We study the space-time evolution of “flavor” neutrino wave packets at finite temperature and density in the early Universe prior to big bang nucleosynthesis (BBN). We implement nonequilibrium field theory methods and linear response to study the space-time evolution directly from the effective Dirac equation in the medium. There is a rich hierarchy of time scales associated with transverse and longitudinal dispersion and coherence. A phenomenon of “freezing of coherence” is a result of a competition between longitudinal dispersion and the separation of wave packets of propagating modes in the medium. Near a resonance the coherence and oscillation time scales are enhanced by a factor $1/\sin 2\theta$ compared to the vacuum. Collisional relaxation via charged and neutral currents occurs on time scales much shorter than the coherence time scale and for small vacuum mixing angle, shorter than the oscillation scale. Assuming that the momentum spread of the initial wave packet is determined by the large angle scattering mean free path of charged leptons, we find that the transverse dispersion time scale is the shortest and is responsible for a large suppression in both the survival and transition probabilities on time scales much shorter than the Hubble time. For small mixing angle the oscillation time scale is longer than the collisional relaxation scale. The method also yields the evolution of right-handed wave packets. Corrections to the oscillation frequencies emerge from wave-packet structure as well as from the energy dependence of mixing angles in the medium.

There are some points to notice in the dimensional reduction of off-shell supergravity. We discuss a consistent way of dimensional reduction of five-dimensional off-shell supergravity compactified on $S^1/Z_2$. There are two approaches to the four-dimensional effective action, which are complementary to each other. Their essential difference is the treatment of the compensator and the radion superfields. We explain these approaches in detail and examine their consistency. Comments on related works are also provided.

In phenomenological quantum gravity theories, Planckian behavior is triggered by the energy of elementary particles approaching the Planck energy, $E_P$, but it is also possible that anomalous behavior strikes systems of particles with total energy near $E_P$. This is usually perceived to be pathological and has been labeled “the soccer ball problem.” We point out that there is no obvious contradiction with experiment if coherent collections of particles with bulk energy of order $E_P$ do indeed display Planckian behavior, a possibility that would open a new experimental window. Unfortunately, field theory realizations of “doubly” (or deformed) special relativity never exhibit a soccer ball problem; we present several formulations where this is undeniably true. Upon closer scrutiny we discover that the only chance for Planckian behavior to be triggered by large coherent energies involves the details of second quantization. We find a formulation where the quanta have their energy-momentum (mass-shell) relations deformed as a function of the bulk energy of the coherent packet to which they belong, rather than the frequency. Given ongoing developments in laser technology, such a possibility would be of great experimental interest.

We show that the problem of stabilization of extra dimensions in Kaluza-Klein type cosmology may be solved in a theory of gravity involving high-order curvature invariants. The method suggested (employing a slow-change approximation) can work with a rather general form of the gravitational action. As examples, we consider pure gravity with Lagrangians quadratic and cubic in the scalar curvature and some more complex ones in a simple Kaluza-Klein framework. After a transition to the 4D Einstein conformal frame, this results in effective scalar field theories with certain effective potentials, which in many cases possess positive minima providing stable small-size extra dimensions. Estimates made in the original (Jordan) conformal frame show that the problem of a small value of the cosmological constant in the present Universe is softened in this framework but is not solved completely.

In this paper we analyze the interaction of a uniformly accelerated detector with a quantum field in $(3+1)\mathrm{D}$ spacetime, aiming at the issue of how kinematics can render vacuum fluctuations the appearance of thermal radiance in the detector (Unruh effect) and how they engender flux of radiation for observers afar. Two basic questions are addressed in this study: (a) How are vacuum fluctuations related to the emitted radiation? (b) Is there emitted radiation with energy flux in the Unruh effect? We adopt a method which places the detector and the field on an equal footing and derive the two-point correlation functions of the detector and of the field separately with full account of their interplay. From the exact solutions, we are able to study the complete process from the initial transient to the final steady state, keeping track of all activities they engage in and the physical effects manifested. We derive a quantum radiation formula for a Minkowski observer. We find that there does exist a positive radiated power of quantum nature emitted by the detector, with a hint of certain features of the Unruh effect. We further verify that the total energy of the dressed detector and a part of the radiated energy from the detector is conserved. However, this part of the radiation ceases in steady state. So the hint of the Unruh effect in radiated power is actually not directly from the energy flux that the detector experiences in Unruh effect. Since all the relevant quantum and statistical information about the detector (atom) and the field can be obtained from the results presented here, they are expected to be useful, when appropriately generalized, for addressing issues of quantum information processing in atomic and optical systems, such as quantum decoherence, entanglement, and teleportation.

We investigate a novel approach which improves the sensitivity of a gravitational-wave interferometer due to the phenomenon of stochastic resonance (SR), performing in a nonlinear cavity (NC). The NC is installed at the output of the interferometer before the photodetector so that the optical signal emerging from the interferometer passes through the NC. Under appropriate circumstances, a specific transformation of the noisy signal inside the NC takes place, which results in the increase of the output signal-to-noise ratio (SNR). As a result, the noisy optical signal of the interferometer becomes less noisy after passing through the NC. The improvement of SNR is especially effective in the bistable NC for wideband (several hundred Hz) detection, when the chirp gravitational-wave signal is detected. Then, for an input SNR of $\sim 0.05$, the output SNR can be increased up to $\sim 0.5$. When the detection bandwidth is narrowed, the SR mechanism gradually fades out, and the SNR gain tends to 1. The SNR gain also tends to 1 when the NC is transformed to a linear cavity. Proposed enhancement of the SNR due to SR is not dependent on noise type, which dominates in the interferometer. Particularly, the proposed approach is capable of increasing the SNR at a given amplitude of displacement noise.

Nonperturbative results for improvement and renormalization constants needed for on-shell and off-shell $O(a)$ improvement of bilinear operators composed of Wilson fermions are presented. The calculations have been done in the quenched approximation at $\beta =6.0$, 6.2, and 6.4. To quantify residual discretization errors we compare our data with results from other nonperturbative calculations and with one-loop perturbation theory.

The bulk distribution of the topological charge density, constructed via the ${\mathrm{HP}}^1$ $\sigma$-model embedding method, is investigated. We argue that the specific pattern of leading power corrections to gluon condensate hints on a particular UV divergent structure of ${\mathrm{HP}}^1$ $\sigma$-model fields, which in turn implies the linear divergence of the corresponding topological density in the continuum limit. We show that under testable assumptions, the topological charge is to be distributed within three-dimensional sign-coherent domains and, conversely, the dimensionality of sign-coherent regions dictates the leading divergence of the topological density. Confronting the proposed scenario with lattice data we present evidence for indeed peculiar divergence of the embedded fields. Then the UV behavior of the topological density is studied directly and is found to agree with our proposition. Finally, we introduce a method to investigate the dimensionality of relevant topological fluctuations and show that indeed topological charge sign-coherent regions are likely to be three-dimensional.

The decay channel $J/\psi \to \gamma \omega \omega$, $\omega \to {\pi }^{+}{\pi }^{-}{\pi }^0$ is analyzed using a sample of $5.8\times {10}^7$ $J/\psi$ events collected with the BESII detector. The $\omega \omega$ invariant mass distribution peaks at $1.76\mathrm{GeV}/c^2$, just above the $\omega \omega$ threshold. Analysis of angular correlations indicates that the $\omega \omega$ system below $2\mathrm{GeV}/c^2$ is predominantly pseudoscalar. A partial wave analysis confirms the predominant pseudoscalar structure, together with small $0^{++}$ and $2^{++}$ contributions, and yields a pseudoscalar mass $\mathrm{M}=1744\pm 10(\mathrm{stat})\pm 15(\mathrm{syst})\mathrm{MeV}/c^2$, a width $\Gamma ={244}_{-21}^{+24}(\mathrm{stat})\pm 25(\mathrm{syst})\mathrm{MeV}/c^2$, and a product branching fraction $\mathrm{Br}(J/\psi \to \gamma \eta (1760))·\mathrm{Br}(\eta (1760)\to \omega \omega )=(1.98\pm 0.08(\mathrm{stat})\pm 0.32(\mathrm{syst}))\times {10}^{-3}$.

We discuss the properties of the gravitational energy-momentum 3-form within the tetrad formulation of general relativity theory. We derive the covariance properties of the quantities describing the energy-momentum content under Lorentz transformations of the tetrad. As an application, we consider the computation of the total energy (mass) of some exact solutions of Einstein’s general relativity theory which describe compact sources with asymptotically flat spacetime geometry. As it is known, depending on the choice of tetrad frame, the formal total integral for such configurations may diverge. We propose a natural regularization method which yields finite values for the total energy-momentum of the system and demonstrate how it works on a number of explicit examples.

We consider the most general higher-order corrections to the pure gravity action in $D$ dimensions constructed from the basis of the curvature monomial invariants of order 4 and 6, and degree 2 and 3, respectively. Perturbatively solving the resulting sixth-order equations we analyze the influence of the corrections upon a static and spherically symmetric back hole. Treating the total mass of the system as the boundary condition we calculate location of the event horizon, modifications to its temperature and the entropy. The entropy is calculated by integrating the local geometric term constructed from the derivative of the Lagrangian with respect to the Riemann tensor over a spacelike section of the event horizon. It is demonstrated that identical result can be obtained by integration of the first law of the black hole thermodynamics with a suitable choice of the integration constant. We show that reducing coefficients to the Lovelock combination, the approximate expression describing entropy becomes exact. Finally, we briefly discuss the problem of field redefinition and analyze consequences of a different choice of the boundary conditions in which the integration constant is related to the exact location of the event horizon and thus to the horizon defined mass.

Numerous nonstandard dynamics dominated by very high mass exchanges are described at current and future accelerator energies by appropriate contactlike effective interactions among the standard model particles. Correspondingly, they can manifest themselves only through deviations of the cross sections from the standard model predictions. If one such deviation were observed, it would be important to definitely identify, to a given confidence level, the actual source among the various possible nonstandard interactions that, in principle, can explain it. Here we estimate the identification reach on different new physics effective interactions, obtainable from angular distributions of lepton pair production processes at the planned electron-positron International Linear Collider with polarized beams. For each nonstandard model, such an identification reach defines the range in the relevant heavy mass scale parameter where it can be unambiguously distinguished from the other nonstandard models as the source of corrections to the standard model cross sections, in case these are observed. The effective interactions for which we estimate the expected identification reach are the interactions based on gravity in large extra dimensions, in ${\mathrm{TeV}}^{-1}$ extra dimensions and the compositeness-inspired four-fermion contact interactions. The availability of both beams polarized at the International Linear Collider turns out, in many cases, to dramatically enhance the identification sensitivity.

We reinvestigated the parameter space allowing a large branching ratio (BR) of the 4-body decay of the lighter top squark (${\tilde{t}}_1$) accessible at Tevatron Run-II by imposing the lighter $CP$-even Higgs boson mass ($m_{h^0}$) bound from LEP. Important constraints were obtained in mSUGRA as well as in the unconstrained supersymmetric models. Our results show that the prospect of searching the lighter top squark via the 4-body decay mode, in particular, the $\ell +n-\mathrm{\text{jets}}+{\mathrm{E̸}}_T$ signal, is not promising in mSUGRA due to the above bound on $m_{h^0}$. The existing bounds on $m_{{\tilde{t}}_1}$ from Tevatron Run-I and LEP assuming 100% BR of the loop decay of ${\tilde{t}}_1$ are, therefore, valid to a good approximation. We also find that large BRs of the above 4-body decay are allowed in the unconstrained model over significant regions of parameter spaces and the possibility that this decay mode is the main discovery channel at Tevatron Run-II is open. We have briefly reviewed the theoretical uncertainties in the calculation of $m_{h^0}$ and their consequences for the constraints obtained by us. We have commented upon, with illustrative examples, how the above parameter space is affected if future experiments push the Higgs boson mass bound upward.