We present an exact solution describing a stationary and axisymmetric object with electromagnetic and dilaton fields. The solution generalizes the usual Kerr-Taub-NUT (Newman-Unti-Tamburino) spacetime in general relativity and is obtained by boosting this spacetime in the fifth dimension and performing a Kaluza-Klein reduction to four dimensions. We also discuss the physical parameters of this solution and calculate its gyromagnetic ratio.

In order to make useful comparisons of different dark energy experiments, it is important to choose the appropriate figure of merit (FoM) for dark energy constraints. Here we show that for a set of dark energy parameters $\{f_i\}$, it is most intuitive to define $\mathrm{FoM}=1/\sqrt{\det \mathrm{Cov}(f_1,f_2,f_3,\dots )}$, where $\mathrm{Cov}(f_1,f_2,f_3,\dots )$ is the covariance matrix of $\{f_i\}$. In order for this FoM to represent the dark energy constraints in an optimal manner, the dark energy parameters $\{f_i\}$ should have clear physical meaning and be minimally correlated. We demonstrate two useful choices of $\{f_i\}$ using 182 SNe Ia (from the HST/GOODS program, the first year Supernova Legacy Survey, and nearby SN Ia surveys), $[R(z_{*}),l_a(z_{*}),{\Omega }_b{h}^2]$ from the five year Wilkinson Microwave Anisotropy Probe observations, and Sloan Digital Sky Survey measurement of the baryon acoustic oscillation scale, assuming the Hubble Space Telescope prior of $H_0=72\pm 8(\mathrm{km}/\mathrm{s}){\mathrm{Mpc}}^{-1}$, and without assuming spatial flatness. We find that for a dark energy equation of state linear in the cosmic scale factor $a$, the correlation of $(w_0,w_{0.5})$ [$w_0=w_X(z=0)$, $w_{0.5}=w_X(z=0.5)$, with $w_X(a)=3w_{0.5}-2w_0+3(w_0-w_{0.5})a$] is significantly smaller than that of $(w_0,w_a)$ [with $w_X(a)=w_0+(1-a)w_a$]. In order to obtain model-independent constraints on dark energy, we parametrize the dark energy density function $X(z)={\rho }_X(z)/{\rho }_X(0)$ as a free function with $X_{0.5}$, $X_{1.0}$, and $X_{1.5}$ [values of $X(z)$ at $z=0.5$, 1.0, and 1.5] as free parameters estimated from data. If one assumes a linear dark energy equation of state, current observational data are consistent with a cosmological constant at 68% C.L. If one assumes $X(z)$ to be a free function parametrized by $(X_{0.5},X_{1.0},X_{1.5})$, current data deviate from a cosmological constant at $z=1$ at 68% C.L., but are consistent with a cosmological constant at 95% C.L. Future dark energy experiments will allow us to dramatically increase the FoM of constraints on $(w_0,w_{0.5})$, and of $(X_{0.5},X_{1.0},X_{1.5})$. This will significantly shrink the dark energy parameter space to either enable the discovery of dark energy evolution, or the conclusive evidence for a cosmological constant.

We revisit inflationary cosmology of axion models in the light of recent developments on the inflaton decay in supergravity. We find that all the cosmological difficulties, including gravitino, axino overproduction, and axionic isocurvature fluctuation, can be avoided if the saxion field has large initial amplitude during inflation and decays before big bang nucleosynthesis.

The annihilations of neutralino dark matter (or other dark matter candidate) generate, among other standard model states, electrons and positrons. These particles emit synchrotron photons as a result of their interaction with the galactic magnetic field. In this paper, we use the measurements of the Wilkinson Microwave Anisotropy Probe satellite to constrain the intensity of this synchrotron emission and, in turn, the annihilation cross section of the lightest neutralino. We find this constraint to be more stringent than that provided by any other current indirect detection channel. In particular, the neutralino annihilation cross section must be less than $\approx 3\times {10}^{-26}{\mathrm{cm}}^3/\mathrm{s}$ ($1\times {10}^{25}{\mathrm{cm}}^3/\mathrm{s}$) for 100 GeV (500 GeV) neutralinos distributed with a Navarro-Frenk-White halo profile. For the conservative case of an entirely flat dark matter distribution within the inner 8 kiloparsecs of the Milky Way, the constraint is approximately a factor of 30 less stringent. Even in this conservative case, synchrotron measurements strongly constrain, for example, the possibility of wino or Higgsino neutralino dark matter produced nonthermally in the early universe.

Recently, triggers occurring during high background rate intervals have been reporter by the Swift-BAT gamma-ray burst detector. Among them, there were two on January 24, two on January 25, and two on February 13 and 18, all in 2008. These Swift-BAT triggers in most cases are probably noise triggers that occurred while Swift was entering the South Atlantic Anomaly (SAA). In fact, we show that they happen during a plentiful precipitation of high energy particles in the SAA, producing muons in the atmosphere detected by two directional telescopes at sea level, inside the SAA region (Tupi experiment). They look like sharp peaks in the muon counting rate. In the same category are two triggers from the MILAGRO ground-based detector, on January 25 and 31, 2008, respectively. In addition, the trigger coordinates are close to (and, in two cases, inside) the field of view of the telescopes. From an additional analysis in the behavior of the muon counting rate, it is possible to conclude that the events are produced by precipitation of high energy charged particles in the SAA region. Thus, due to its localization, the Tupi experiment constitutes a new sensor of high energy particle precipitation in the SAA, and it can be useful in the identification of some triggers of gamma-ray burst detectors.

A recent work by Dubeibe et al. [Phys. Rev. D 75, 023008 (2007)] stated that chaos phenomenon of test particles in gravitational field of rotating neutron stars which are described by Manko, Sanabria-Goméz, and Manko (Manko et al.) metric can only occur when the stars have oblate deformation. But the chaotic motions they found are limited in a very narrow zone which is very close to the center of the massive bodies. This paper argues that this is impossible because the region is actually inside of the stars, so the motions cannot exist at this place. In this paper, we scan all parameters space and find chaos and unstable fixed points outside of stars with big mass-quadrupole moments. The calculations show that chaos can only occur when the stars have prolate deformation. Because real deformation of stars should be oblate, all orbits of test particles around the rotating neutron stars described by Manko et al. solutions are regular. The case of nonzero dipolar magnetic moment has also been taken into account in this study.

We calculate the quantum noise limited displacement sensitivity of a Michelson-Fabry-Perot (MFP) interferometer with detuned cavities, followed by phase-sensitive homodyne detection. We show that the standard quantum limit can be surpassed even with resonant cavities and without any signal-recycling mirror nor additional cavities. Indeed, thanks to the homodyne detection, the output field quadrature can be chosen in such a way to cancel the effect of input amplitude fluctuations, i.e., eliminating the force noise. With detuned cavities, the modified opto-mechanical susceptivity allows to reach unlimited sensitivity for large enough (yet finite) optical power. Our expressions include mirror losses and cavity delay effect, for a realistic comparison with experiments. Our study is particularly devoted to gravitational wave detectors and we consider both an interferometer with free-falling mirrors, and a MFP interferometer as readout for a massive detector. In the latter case, the sensitivity curve of the recently conceived “DUAL” detector, based on two acoustic modes, is obtained.

We introduce, in a systematic way, a set of generating functions that solve all the different combinatorial problems that crop up in the study of black hole entropy in loop quantum gravity. Specifically we give generating functions for the following: the different sources of degeneracy related to the spectrum of the area operator, the solutions to the projection constraint, and the black hole degeneracy spectrum. Our methods are capable of handling the different countings proposed and discussed in the literature. The generating functions presented here provide the appropriate starting point to extend the results already obtained for microscopic black holes to the macroscopic regime—in particular those concerning the area law and the appearance of an effectively equidistant area spectrum.

We construct a symplectic isomorphism $\mathfrak{h}$ from classical Klein Gordon solutions of mass $m$ on ($d+1$)-dimensional Lorentzian anti–de Sitter space (equipped with the usual symplectic form) to a certain symplectic space of functions on its conformal boundary (only) for all integer and half-integer $\Delta$ ($=\frac{d}{2}+\frac{1}{2}(d^2+4m^2{)}^{1/2}$). $\mathfrak{h}$ induces a large family of new examples of Rehren’s algebraic holography in which the net of local quantum Klein Gordon algebras in AdS is seen to map to a suitably defined net of local algebras for the (generalized free) scalar conformal field with anomalous dimension $\Delta$ on $d$-dimensional Minkowski space (the AdS boundary). Relatedly, we show for these models that Bertola et al.’s boundary-limit holography becomes a quantum duality (only) if the test functions for boundary Wightman distributions are restricted in a particular way.

If the CERN LHC discovers a $Z^{\prime }$-like state, the extraction of its couplings to the particles of the standard model becomes mandatory in order to determine the nature of the underlying new physics theory. It has been well known for some time that the direct measurements performed at the LHC in the Drell-Yan channel cannot determine these parameters uniquely in a model-independent manner even if large integrated luminosities ($\sim 100{\mathrm{fb}}^{-1}$) become available and the $Z^{\prime }$ is relatively light $\lesssim 1.5\mathrm{TeV}$. Here we examine the possibility that a proposed $e_{L,R}^{\pm }p$ collider upgrade at the LHC, the LHeC, with $\sqrt{s}=1.5–2\mathrm{TeV}$ could be helpful with such coupling determinations in the years before a linear collider is constructed. We show that the polarization and charge asymmetries constructed from the cross sections for these processes can be useful in this regard depending upon the specific values of the particular $Z^{\prime }$ model parameters.

We study the phenomenology of supersymmetric models in which gauge-singlet scalars mix with the minimal supersymmetric standard model (MSSM) sneutrinos through weak-scale $A$ terms. After reviewing the constraints on mixed-sneutrino dark matter from measurements of ${\Omega }_{\mathrm{CDM}}$ and from direct-detection experiments, we explore mixed-sneutrino signatures relevant to the LHC. For a mixed-sneutrino lightest supersymmetric particle (LSP) and a right-handed slepton next-to-lightest supersymmetric particle (NLSP), decays of the lightest neturalino can produce opposite-sign, same-flavor (OSSF) dileptons with an invariant-mass distribution shifted away from the kinematic end point. This signature is possible for parameters that lead to a cosmologically viable mixed-sneutrino LSP. We also consider signatures that require larger mixing angles than preferred for mixed-sneutrino dark matter, but which are possible regardless of whether a mixed-sneutrino is the LSP. In some parameter regions, the charginos and neutralinos produced in cascades all decay dominantly to the lighter sneutrinos, leading to a kinematic edge in the jet-lepton invariant-mass distribution from the decay chain $\tilde{q}\to {\chi }^{-}q\to {\tilde{\nu }}^{*}lq$, without an OSSF dilepton signature. We explore the possibility of using mass-estimation methods to distinguish this mixed-sneutrino jet-lepton signature from an MSSM one. Finally, we consider signatures associated with Higgs-lepton or $Z$-lepton production in cascades involving the heavier sneutrinos.

QCD at a finite quark-number chemical potential $\mu$ has a complex fermion determinant, which precludes its study by standard lattice QCD simulations. We therefore simulate lattice QCD at finite $\mu$ in the phase-quenched approximation, replacing the fermion determinant with its magnitude. (The phase-quenched approximation can be considered as simulating at finite isospin chemical potential $2\mu$ for $N_f/2$ $u$-type and $N_f/2$ $d$-type quark flavors.) These simulations are used to study the finite-temperature transition for small $\mu$, where there is some evidence that the position (and possibly the nature) of this transition is unchanged by this approximation. We look for the expected critical endpoint for 3-flavor QCD. Here, it has been argued that the critical point at zero $\mu$ would become the critical endpoint at small $\mu$, for quark masses just above the critical mass. Our simulations indicate that this does not happen, and there is no such critical endpoint for small $\mu$. We discuss how we might adapt techniques used for imaginary $\mu$ to improve the signal/noise ratio and strengthen our conclusions, using results from relatively low statistics studies.

The calculation of the finite lattice spacing corrections for $\mathrm{I}=2$ $\pi \pi$ scattering is carried out for isotropic and anisotropic Wilson lattice actions. Pion masses and decay constants are also determined in this context. These results correct the phase shift calculated from the lattice, which is connected to the scattering length and effective range in this low energy scattering process. When in terms of the lattice-physical parameters for either Wilson action, these lattice spacing effects first appear at the next-to-leading order counterterms.

I investigate the determination of the $\sigma$ pole from $\pi \pi$ scattering data below the $K\overline{K}$ threshold, including the new precise results obtained from $K_{e4}$ decay by $\mathrm{NA}48/2$ Collaboration. I discuss also the experimental status of the threshold parameters $a_0^0$ and $b_0^0$ and the phase shift ${\delta }_0^0$. In order to reduce the theoretical bias, I use a large class of analytic parametrizations of the isoscalar $S$ wave, based on expansions in powers of conformal variables. The $\sigma$ pole obtained with this method is consistent with the prediction based on ChPT and Roy equations. However, the theoretical uncertainties are now larger, reflecting the sensitivity of the pole position to the specific parametrizations valid in the physical region. I conclude that Roy equations offer the most precise method for the determination of the $\sigma$ pole from $\pi \pi$ elastic scattering.

Spectral sums of the Dirac-Wilson operator and their relation to the Polyakov loop are thoroughly investigated. The approach by Gattringer is generalized to mode sums which reconstruct the Polyakov loop locally. This opens the possibility to study the mode sum approximation to the Polyakov loop correlator. The approach is rederived for the ab initio continuum formulation of Yang-Mills theories, and the convergence of the mode sum is studied in detail. The mode sums are then explicitly calculated for the Schwinger model and $SU(2)$ gauge theory in a homogeneous background field. Using $SU(2)$ lattice gauge theory, the IR dominated mode sums are considered and the mode sum approximation to the static quark antiquark potential is obtained numerically. We find a good agreement between the mode sum approximation and the static potential at large distances for the confinement and the high temperature plasma phase.

We report on a new measurement of the branching ratio $B(K_L\to {\pi }^0\gamma \gamma )$ using the KTeV detector. We reconstruct 1982 events with an estimated background of 608, that results in $B(K_L\to {\pi }^0\gamma \gamma )=(1.29\pm {0.03}_{\mathrm{stat}}\pm {0.05}_{\mathrm{syst}})\times {10}^{-6}$. We also measure the parameter, $a_V$, which characterizes the strength of vector meson exchange terms in this decay. We find $a_V=-0.31\pm {0.05}_{\mathrm{stat}}\pm {0.07}_{\mathrm{syst}}$. These results utilize the full KTeV data set collected from 1997 to 2000 and supersede earlier KTeV measurements of the branching ratio and $a_V$.

A Comment on the article by Anchordoqui et al. “Hunting long-lived gluinos at the Pierre Auger Observatory” [L. A. Anchordoqui, A. Delgado, C. A. García Canal, and S. J. Sciutto, Phys. Rev. D 77, 023009 (2008)].

The contribution of different modes of the Coulomb field to decoherence and to the dynamical breakdown of the time reversal invariance is calculated in the one-loop approximation for nonrelativistic electron gas. The dominant contribution was found to come from the usual collective modes in the plasma, namely, the zero-sound and the plasmon oscillations. The length scale of the quantum-classical transition is found to be close to the Thomas-Fermi screening length. It is argued that the extension of these modes to the whole Fock space yields optimal pointer states.

We continue explorations of non-Abelian strings, focusing on the solution of a heterotic deformation of the $CP(N-1)$ model with an extra right-handed fermion field and $\mathcal{N}=(0,2)$ supersymmetry. This model emerges as a low-energy theory on the world sheet of the Bogomol’nyi-Prasad-Sommerfield-saturated flux tubes (strings) in $\mathcal{N}=2$ supersymmetric QCD deformed by a superpotential of a special type breaking $\mathcal{N}=2$ supersymmetry down to $\mathcal{N}=1$. Using large-$N$ expansion we solve this model to the leading order in $1/N$. Our solution exhibits spontaneous supersymmetry breaking for all values of the deformation parameter. We identify the Goldstino field. The discrete $Z_{2N}$ symmetry is shown to be spontaneously broken down to $Z_2$; therefore the world sheet model has $N$ strictly degenerate vacua (with nonvanishing vacuum energy). Thus, the heterotic $CP(N-1)$ model is in the deconfinement phase. We can compare this dynamical pattern, on the one hand, with the $\mathcal{N}=(2,2)$ $CP(N-1)$ model which has $N$ degenerate vacua with unbroken supersymmetry, and, on the other hand, with the nonsupersymmetric $CP(N-1)$ model with split quasivacua and the Coulomb/confining phase. We determine the mass spectrum of the heterotic $CP(N-1)$ model in the large-$N$ limit.