We discuss the possibility of testing the weak currents and, in particular, the weak magnetism term through the measurement of the ${\overline{\nu }}_e+p\to e^{+}+n$ reaction at a low energy beta-beam facility. We analyze the sensitivity using both the total number of events and the angular distribution of the positrons emitted in a water Čerenkov detector. We show that the weak magnetism form factor might be determined with better than several percent accuracy using the angular distribution. This offers a new way of testing the conserved vector current hypothesis.

At the 12-GeV proton synchrotron of KEK, an experiment (KEK-PS-E246) was performed to measure the transverse muon polarization ($P_T$) in $K^{+}\to {\pi }^0{\mu }^{+}\nu$ decays as a direct search of violation of time reversal invariance ($T$-violation). $P_T$ is a very sensitive probe of $CP$ violation beyond the standard model. A stopped positive kaon beam was used. An elaborate high-acceptance detector, in conjunction with a 12-sector superconducting toroidal spectrometer, was utilized. The stopped kaon method provided several advantages in performing a high-precision experiment. The decay was identified by detecting a ${\mu }^{+}$ with the spectrometer and a ${\pi }^0$ with a CsI(Tl) calorimeter surrounding the target as two photons as well as one photon with high energy. For the $P_T$ measurement, ${\pi }^0$ events in the forward (fwd) and backward (bwd) regions in the calorimeter were relevant. Systematic errors were greatly suppressed by exploiting the rotational and fwd-bwd symmetry of the system. Polarization measurement was done in terms of asymmetry measurement of decay positrons of stopped muons in the polarimeter. A longitudinal field method was applied for the $P_T$ polarization component. In the data analysis a novel technique of the two-analysis method was employed. Two independent analyses were performed following their own policy and criteria and good events were selected. Then, the two analyses were combined. A data quality check was carefully done by looking at the null asymmetry $A_0$, the sensitivity function $A_N$, the kinematical attenuation coefficient, and the decay-plane distributions. The asymmetry measurement for finite-size muon stoppers was performed “differentially” using the position information by the chamber in front of the polarimeter. From the measurements during 1996–2000, we accumulated $11.8\times {10}^6$ good events after the two-analysis combination, and deduced $P_T=-0.0017\pm 0.0023(\mathrm{stat})\pm 0.0011(\mathrm{syst})$, corresponding to the $T$-violating parameter $\mathrm{Im}\xi =-0.0053\pm 0.0071(\mathrm{stat})\pm 0.0036(\mathrm{syst})$. From these results the upper limits of $|P_T|<0.0050$ (90% C.L.) and $|\mathrm{Im}\xi |<0.016$ (90% C.L.) were deduced. Systematic errors were carefully studied and estimated. Almost all of the errors were canceled by the 12-sector summation and/or fwd-bwd subtraction, and the total systematic error was concluded to be as a half of the statistical error. The present result set constraints on model parameters of several theoretical models. For the three-Higgs-doublet model, e.g., a limit $|\mathrm{Im}({\alpha }_1{\gamma }_1^{*})|<544(M_{H_1}/\mathrm{GeV}{)}^2$ was obtained. Implications for several other models are discussed.

In this paper we consider classical and quantum corrections to cosmological solutions of 11D supergravity (SUGRA) coming from dynamics of membrane states. We first consider the supermembrane spectrum following the approach of Russo and Tseytlin for consistent quantization. We calculate the production rate of Bogomol’nyi-Prasad-Sommerfield (BPS) membrane bound states in a cosmological background and find that such effects are generically suppressed by the Planck scale, as expected. However, for a modified brane spectrum possessing enhanced symmetry, production can be finite and significant. We stress that this effect could not be anticipated given only a knowledge of the low-energy effective theory. Once on shell, inclusion of these states leads to an attractive force pulling the dilaton towards a fixed point of $S$-duality, namely $g_s=1$. Although the SUGRA description breaks down in this regime, inclusion of the enhanced states suggests that the center of M-theory moduli space is a dynamical attractor. Moreover, our results seem to suggest that string dynamics does indeed favor a vacuum near fixed points of duality.

We investigate the energy of a theory with a unit vector field (the aether) coupled to gravity. Both the Weinberg and Einstein type energy-momentum pseudotensors are employed. In the linearized theory we find expressions for the energy density of the 5 wave modes. The requirement that the modes have positive energy is then used to constrain the theory. In the fully nonlinear theory we compute the total energy of an asymptotically flat spacetime. The resulting energy expression is modified by the presence of the aether due to the nonzero value of the unit vector at infinity and its $1/r$ falloff. The question of nonlinear energy positivity is also discussed, but not resolved.

We discuss radiative corrections to how quark mass thresholds are crossed, as a function of the temperature, in basic thermodynamic observables such as the pressure, the energy and entropy densities, and the heat capacity of high temperature QCD. The indication from leading order that the charm quark plays a visible role at surprisingly low temperatures, is confirmed. We also sketch a way to obtain phenomenological estimates relevant for generic expansion rate computations at temperatures between the QCD and electroweak scales, pointing out where improvements over the current knowledge are particularly welcome.

In this paper we write down the equation for a scalar conformally coupled field simultaneously for de Sitter (dS), anti-de Sitter (AdS), and Minkowski spacetimes in $d$ dimensions. The curvature dependence appears in a very simple way through a conformal factor. As a consequence the process of curvature free limit, including wave functions limit and two-points functions, turns out to be a straightforward issue. We determine a set of modes, that we call de Sitter plane waves, which become ordinary plane waves when the curvature vanishes.

Braneworld cosmology has several attractive and distinctive features. For instance the effective equation of state in braneworld models can be both quintessencelike ($w_0\ge -1$) as well as phantomlike ($w_0\le -1$). Models with $w_0\ge -1$ ($w_0\le -1$) are referred to as Brane 2 (Brane 1) and correspond to complementary embeddings of the brane in the bulk. (The equation of state in Brane 1 can successfully cross the “phantom divide“ at $w=-1$.) In this paper we compare the predictions of braneworld models to two recently released supernova data sets: the “Gold” data (Riess et al., 2004) and the data from the Supernova Legacy Survey (SNLS) (Astier et al., 2005). We also incorporate the recent discovery of the baryon acoustic peak in the Sloan Digital Sky Survey (Eisenstein et al., 2005) into our analysis. Our main results are that braneworld models satisfy both sets of SNe data. Brane 1 (with $w_0\le -1$) shows very good agreement with data for values of the matter density bounded from below: ${\Omega }_{0\mathrm{m}}\gtrsim 0.25$ (Gold) and ${\Omega }_{0\mathrm{m}}\gtrsim 0.2$ (SNLS). On the other hand Brane 2 (with $w_0\ge -1$) shows excellent agreement with data for values of the matter density which are bounded from above: ${\Omega }_{0\mathrm{m}}\lesssim 0.45$ (Gold) and ${\Omega }_{0\mathrm{m}}\lesssim 0.35$ (SNLS). The DGP model is excluded at $3\sigma$ by SNLS and at $1\sigma$ by the Gold dataset. Braneworld models with future “quiescent” singularities (at which the Hubble parameter and the matter density remain finite but higher derivatives of the expansion factor diverge) are excluded by both datasets.

We present a phenomenological investigation of non-Gaussian effects that could be seen on CMB temperature maps. Explicit expressions for the temperature correlation functions are given for different types of primordial mode couplings. We argue that a simplified description of the radial transfer function for the temperature anisotropies allows one to get insights into the general properties of the bispectrum and trispectrum. The accuracy of these results is explored together with the use of the small scale approximation to get explicit expressions of high order spectra. The bispectrum is found to have alternate signs for the successive acoustic peaks. Sign patterns for the trispectrum are more complicated and depend specifically on the type of metric couplings. Local primordial couplings are found to give patterns that are different from those expected from weak lensing effects.

Nearby sources of cosmic rays up to a $\mathrm{ZeV}(={10}^{21}\mathrm{eV})$ could be observed with a multimessenger approach including secondary $\gamma$-rays and neutrinos. If cosmic rays above $\sim {10}^{18}\mathrm{eV}$ are produced in magnetized environments such as galaxy clusters, the flux of secondary $\gamma$-rays can be enhanced by a factor $\sim 10$ at Gev energies and by a factor of a few at TeV energies, compared to unmagnetized sources. Particularly enhanced are synchrotron and cascade photons from $e^{+}{e}^{-}$ pairs produced by protons from sources with relatively steep injection spectra $\propto E^{-2.6}$. Such sources should be visible at the same time in ultrahigh energy cosmic ray experiments and $\gamma$-ray telescopes.

We present new limits on ultrahigh energy neutrino fluxes above ${10}^{17}\mathrm{eV}$ based on data collected by the Radio Ice Cherenkov Experiment (RICE) at the South Pole from 1999–2005. We discuss estimation of backgrounds, calibration and data analysis algorithms (both online and offline), procedures used for the dedicated neutrino search, and refinements in our Monte Carlo (MC) simulation, including recent in situ measurements of the complex ice dielectric constant. An enlarged data set and a more detailed study of hadronic showers results in a sensitivity improvement of more than 1 order of magnitude compared to our previously published results. Examination of the full RICE data set yields zero acceptable neutrino candidates, resulting in 95% confidence-level model-dependent limits on the flux $E_{\nu }^{2}d\varphi /d{E}_{\nu }<{10}^{-6}\mathrm{GeV}/(\mathrm{c}{\mathrm{m}}^2\mathrm{s}\mathrm{sr})$ in the energy range ${10}^{17}<E_{\nu }<{10}^{20}\mathrm{eV}$. The new RICE results rule out the most intense flux model projections at 95% confidence level.

In an $R$-parity violating (RPV) model of neutrino mass with three bilinear couplings ${\mu }_i$ and three trilinear couplings ${\lambda }_{i33}^{\prime }$, where $i$ is the lepton index, we find six generic scenarios each with a distinctive pattern of the trilinear couplings consistent with the oscillation data. These patterns may be reflected in direct RPV decays of the lighter top squark or in the RPV decays of the lightest superparticle, assumed to be the lightest neutralino. Typical signal sizes at the Tevatron RUN II and the CERN LHC have been estimated and the results turn out to be encouraging.

We calculate isospin 2 pion-pion scattering in chiral perturbation theory for a partially quenched, mixed action theory with Ginsparg-Wilson valence quarks and staggered sea quarks. We point out that for some scattering channels, the power-law volume dependence of two-pion states in nonunitary theories such as partially quenched or mixed action QCD is identical to that of QCD. Thus one can extract infinite-volume scattering parameters from mixed action simulations. We then determine the scattering length for both 2 and $2+1$ sea quarks in the isospin limit. The scattering length, when expressed in terms of the pion mass and the decay constant measured on the lattice, has no contributions from mixed valence-sea mesons, thus it does not depend upon the parameter, $C_{\mathrm{Mix}}$, that appears in the chiral Lagrangian of the mixed theory. In addition, the contributions which nominally arise from operators appearing in the mixed action $\mathcal{O}(a^2{m}_q)$ Lagrangian exactly cancel when the scattering length is written in this form. This is in contrast to the scattering length expressed in terms of the bare parameters of the chiral Lagrangian, which explicitly exhibits all the sicknesses and lattice spacing dependence allowed by a partially quenched mixed action theory. These results hold for both 2 and $2+1$ flavors of sea quarks.

In this work the Poincaré–Chern-Simons and anti-de Sitter–Chern-Simons gravities are studied. For both, a solution that can be cast as a black hole with manifest torsion is found. Those solutions resemble Schwarzschild and Schwarzschild-AdS solutions, respectively.

A metric representing the Kerr geometry has been obtained by Pretorius and Israel. We make coordinate transformations on this metric, to bring it into Bondi-Sachs form. We investigate the behavior of the metric near the axis of symmetry and confirm elementary flatness, and we also confirm that it is asymptotic to the Bondi-Sachs form of the Schwarzschild geometry. The results obtained here are needed so that numerical relativity codes based on the characteristic formalism can be applied to a situation that contains a rotating black hole.

We calculate the cosmic microwave background (CMB) angular trispectrum, spherical harmonic transform of the four-point correlation function, from primordial non-Gaussianity in primordial curvature perturbations characterized by a constant nonlinear coupling parameter, $f_{\mathrm{NL}}$. We fully take into account the effect of the radiation transfer function, and thus provide the most accurate estimate of the signal-to-noise ratio of the angular trispectrum of CMB temperature anisotropy. We find that the predicted signal-to-noise ratio of the trispectrum summed up to a given $l$ is approximately a power-law, $(S/N)(<l)\sim 2.2\times {10}^{-9}{f}_{\mathrm{NL}}^2{l}^2$, up to the maximum multipole that we have reached in our numerical calculation, $l=1200$, assuming that the error is dominated by cosmic variance. Our results indicate that the signal-to-noise ratio of the temperature trispectrum exceeds that of the bispectrum at the critical multipole, $l_c\sim 1500(50/|f_{\mathrm{NL}}|)$. Therefore, the trispectrum of the Planck data is more sensitive to primordial non-Gaussianity than the bispectrum for $|f_{\mathrm{NL}}|\gtrsim 50$. We also report the predicted constraints on the amplitude of trispectrum, which may be useful for other non-Gaussian models such as curvaton models.

We investigate the indirect effects of heavy vector bileptons being exchanged in polarized Møller scattering, at the next generation of linear colliders. Considering both longitudinal and transverse beam polarization, and accounting for initial-state radiation, beamstrahlung and beam energy spread, we discuss how angular distributions and asymmetries can be used to detect clear signals of virtual bileptons, and the possibility of distinguishing theoretical models that incorporate these exotic particles. We then estimate 95% C.L. bounds on the mass of these vector bileptons and on their couplings to electrons.

We explore scenarios in which the graviton is not a fundamental degree of freedom at short distances but merely emerges as an effective degree of freedom at long distances. In general, the scale of such graviton “compositeness,” ${\Lambda }_g$, can only be probed by measuring gravitational forces at short distances, which becomes increasingly difficult and eventually impossible as the distance is reduced. Here, however, we point out that if supersymmetry is an underlying symmetry, the gravitino can be used as an alternative probe to place a limit on ${\Lambda }_g$ in a collider environment, by demonstrating that there is a model-independent relation, ${\Lambda }_g\gtrsim m_{3/2}$. In other words, the gravitino knows that gravity is standard at least down to its Compton wavelength, so this can also be viewed as a test of general relativity possible at very short distances. If composite gravity is found first at some ${\Lambda }_g$, this would imply a model-independent upper bound on $m_{3/2}$.

We discuss partially quenched chiral perturbation theory ($\mathrm{PQ}\chi \mathrm{PT}$) and possible fitting strategies to lattice QCD data at next-to-next-to-leading order (NNLO) in the mesonic sector. We also present a complete calculation of the masses of the charged pseudoscalar mesons, in the supersymmetric formulation of $\mathrm{PQ}\chi \mathrm{PT}$. Explicit analytical results are given for up to three nondegenerate sea-quark flavors, along with the previously unpublished expression for the pseudoscalar meson decay constant for three nondegenerate sea-quark flavors. The numerical analysis in this paper demonstrates that the corrections at NNLO are sizable, as expected from earlier work.