We study the fermionic vacuum energy of vacua with and without application of an external magnetic field. The energetic difference of two vacua leads to the vacuum decaying and the vacuum energy being released. In the context of quantum field theories, we discuss why and how the vacuum energy can be released by spontaneous photon emission and/or paramagnetically screening the external magnetic field. In addition, we quantitatively compute the vacuum energy released, the paramagnetic screening effect, and the rate and spectrum of spontaneous photon emission. The possibilities of experimentally detecting such an effect of vacuum-energy release and that this effect accounts for the anomalous x-ray pulsar are discussed.

We analyze the prospects of a feasible, Brookhaven National Laboratory based, very long baseline neutrino oscillation experiment consisting of a conventional horn produced low energy wideband beam and a detector of 500 kton fiducial mass with modest requirements on event recognition and resolution. Such an experiment is intended primarily to determine $\mathrm{CP}$ violating effects in the neutrino sector for 3-generation mixing. We analyze the sensitivity of such an experiment. We conclude that this experiment will allow determination of the $\mathrm{CP}$ phase ${\delta }_{\mathrm{CP}}$ and the currently unknown mixing parameter ${\theta }_{13},$ if ${\sin }^{2}2{\theta }_{13}>~0.01,$ a value $\sim 15$ times lower than the present experimental upper limit. In addition to ${\theta }_{13}$ and ${\delta }_{\mathrm{CP}},$ the experiment has great potential for precise measurements of most other parameters in the neutrino mixing matrix including $\Delta m_{32}^2,$ ${\sin }^{2}2{\theta }_{23},$ $\Delta m_{21}^2\times \sin 2{\theta }_{12},$ and the mass ordering of neutrinos through the observation of the matter effect in the ${\nu }_{\mu }\to {\nu }_e$ appearance channel.

We carefully analyze the supersymmetry algebra of closed strings and open strings in a type IIB plane wave background. We use eight-component chiral spinors, $\mathrm{SO}\left(8\right)\mathrm{}$ chiral spinors, in the light-cone gauge to provide a useful basis for string field theory calculations in a plane wave. We consider the two classes of D-branes, ${\mathrm{D}}_{\pm }$-branes, and give a worldsheet derivation of conserved supercurrents for all half Bogomol’nyi-Prasad-Sommerfield (BPS) D-branes preserving 16 supersymmetries in the type IIB plane wave background. We exhaustively provide the supersymmetry algebra of the half BPS branes as well. We also point out that the supersymmetry algebra distinguishes the two $\mathrm{SO}\left(4\right)\mathrm{}$ directions with different signs, which is consistent with the $Z_2$ symmetry of the string action.

We investigate the real-time tachyon dynamics of an unstable D-brane carrying fundamental string charge. We construct the boundary state relevant for the rolling of the modulated tachyon with gauge fields excited on the world volume, and study the spatial distribution of the fundamental string charge and current as the D-brane decays. We find that, in contrast with homogeneous tachyon rolling, spatial modulation of the tachyon field triggers a density wave of strings when the electric field is turned on and string-antistring pairs when the magnetic field is turned on. We show that the energy density and the fundamental string charge density are locked together and evolve into a localized delta-function array (instead of evolving into a string fluid) until a critical time set by the rolling tachyon’s initial condition. When the gauge fields approach the critical limit, the fundamental strings produced become BPS-like. We also study the dynamics via effective field theory, and find agreement.

In this paper, following the work of Seiberg in a previous paper for the conjecture between the field theory and matrix model in the case of massive fundamental flavors, we generalize it to the case with massless fundamental flavors. We show that with a little modification, the analysis given by Seiberg can be used directly for the case of massless flavors. Furthermore, this new method explains the insertion of $\delta$ functions in the matrix model given by Demasure and Janik.

The one-loop renormalization of the Abelian Higgs-Kibble model in a general ’t Hooft gauge and with chiral fermions is fully worked out within dimensional renormalization scheme with a nonanticommuting ${\gamma }_5.$ The anomalous terms introduced in the Slavnov-Taylor identities by the minimal subtraction algorithm are calculated and the asymmetric counterterms needed to restore the Becchi-Rouet-Stora symmetry, if the anomaly cancellation conditions are met, are computed. The computations draw heavily from regularized action principles and algebraic renormalization theory.

We give a formulation of linearized minimal five-dimensional supergravity in $\mathcal{N}=1\mathrm{}$ superspace. Infinitesimal local 5D diffeomorphisms, local 5D Lorentz transformations, and local 5D supersymmetry are all realized as off-shell superfield transformations. Compactification on an $S^1{/Z}_2$ orbifold and couplings to brane-localized supermultiplets are very simple in this formalism. We use this to show that five-dimensional supergravity can naturally generate μ and $B\mu$ terms of the correct size in gaugino- or radion-mediated supersymmetry breaking. We also include a self-contained review of linearized minimal 4D supergravity in superspace.

We consider sound propagation on M5- and M2-branes in the hydrodynamic limit. In particular, we look at the low energy description of a stack of N M-branes at finite temperature. At low energy, the M-branes are well described, via the AdS/conformal field theory correspondence, in terms of classical solutions to the eleven-dimensional supergravity equations of motion. From this gravitational description, we calculate Lorentzian signature two-point functions of the stress-energy tensor on these M-branes in the long-distance, low-frequency limit, i.e. the hydrodynamic limit. The poles in these Green’s functions show evidence for sound propagation in the field theory living on the M-branes.

Cosmologically motivated theories that explain the small acceleration rate of the Universe via the modification of gravity at very large, horizon, or superhorizon distances, can be tested by precision gravitational measurements at much shorter scales, such as the Earth-Moon distance. Contrary to the naive expectation the predicted corrections to the Einsteinian metric near gravitating sources are so significant that they might fall within the sensitivity of the proposed Lunar Ranging experiments. The key reason for such corrections is the van Dam–Veltman–Zakharov discontinuity present in linearized versions of all such theories, and its subsequent absence at the nonlinear level in the manner of Vainshtein.

I examine the possibility that the third generation fermion masses are determined by an exact fixed point of the minimal supersymmetric SU(5) model. When one-loop supersymmetric thresholds are included, this unified fixed point successfully predicts the top quark mass, $175\pm 2\mathrm{GeV},$ as well as the weak mixing angle. The bottom quark mass prediction is sensitive to the supersymmetric thresholds; it approaches the measured value for $\mu <0\mathrm{}$ and very large unified gaugino mass. The experimental measurement of the tau lepton mass determines $\tan \beta ,$ and the strong gauge coupling and fine structure constant fix the unification scale and the unified gauge coupling.

We present results from a numerical simulation of the two-dimensional Euclidean Wess-Zumino model. In the continuum the theory possesses $N=1\mathrm{}$ supersymmetry. The lattice model we employ was analyzed by Golterman and Petcher, who gave a perturbative proof that the continuum supersymmetric Ward identities are recovered without fine-tuning in the limit of vanishing lattice spacing. Our simulations demonstrate the existence of important non-perturbative effects in finite volumes which modify these conclusions. It appears that in certain regions of parameter space the vacuum state can contain solitons corresponding to field configurations which interpolate between different classical vacua. In the background of these solitons supersymmetry is partially broken and a light fermion mode is observed. At fixed coupling the critical mass separating phases of broken and unbroken supersymmetry appears to be volume dependent. We discuss the implications of our results for continuum supersymmetry breaking.

We study a block spin transformation in the SU(3) lattice gauge theory on anisotropic lattices to obtain Iwasaki’s renormalization-group-improved action for anisotropic cases. For the class of actions with plaquette and $1\times 2$ rectangular terms, we determine the improvement parameters as functions of the anisotropy $\xi {=a}_s{/a}_t.$ We find that the program of improvement works well also on anisotropic lattices. From a study of an indicator which estimates the distance to the renormalized trajectory, we show that, for the range of the anisotropy $\xi \approx 1–4,$ the coupling parameters previously determined for isotropic lattices improve the theory considerably.

In this paper we present an analysis of the recent high-statistical KLOE data on the $\overrightarrow{\phi }\eta {\pi }^0\gamma$ decay. This decay mainly goes through the $a_0\gamma$ intermediate state. The results obtained differ from those of previous fits: the data prefer a high $a_0$ mass and a quite large $a_0$ coupling to the $K\overline{K}.$

We find expressions for the weak decay amplitudes of baryons containing two b quarks (or one b and one c quark—many relationships are the same) in terms of unknown reduced matrix elements. This project was originally motivated by the request of the Fermilab run II b Physics Workshop organizers for a guide to experimentalists in their search for as yet unobserved hadrons. We include an analysis of linear SU(3) breaking terms in addition to relationships generated by unbroken SU(3) symmetry, and relate these to expressions in terms of the complete set of possible reduced matrix elements.

For models with several time-dependent components, generalized entropies can be defined. This is shown for the Bianchi type IX model. We first derive the Cardy-Verlinde formula under the assumption that the first law of thermodynamics is valid. This leads to an explicit expression of the total entropy associated with this type of universe. Assuming the validity of the Cardy entropy formula, we obtain expressions for the corresponding Bekenstein, Bekenstein-Hawking and Hubble entropies. We discuss the validity of the Cardy-Verlinde formula and possible extensions of the outlined procedure to other time-dependent models.

Hydrodynamic fluctuations at a nonzero temperature can cause slow relaxation toward equilibrium even in observables which are not locally conserved. A classic example is the stress-stress correlator in a normal fluid, which, at zero wave number, behaves at large times as $t^{-3/2}.$ A novel feature of the effective theory of hydrodynamic fluctuations in supersymmetric theories is the presence of Grassmann-valued classical fields describing macroscopic supercharge density fluctuations. We show that hydrodynamic fluctuations in supersymmetric theories generate essentially the same long-time power-law tails in real-time correlation functions that are known in simple fluids. In particular, a $t^{-3/2}$ long-time tail must exist in the stress-stress correlator of $\mathcal{N}=4\mathrm{}$ supersymmetric Yang-Mills theory at non-zero temperature, regardless of the value of the coupling. Consequently, this feature of finite-temperature dynamics can provide an interesting test of the AdS/CFT correspondence. However, the coefficient of this long-time tail is suppressed by a factor of ${1/N}_{\mathrm{c}}^2.$ On the gravitational side, this implies that these long-time tails are not present in the classical supergravity limit; they must instead be produced by one-loop gravitational fluctuations.

At the threshold of black hole formation in the gravitational collapse of a scalar field a naked singularity is formed through a universal critical solution that is discretely self-similar. We study the global spacetime structure of this solution. It is spherically symmetric, discretely self-similar, regular at the center to the past of the singularity, and regular at the past light cone of the singularity. At the future light cone of the singularity, which is also a Cauchy horizon, the curvature is finite and continuous but not differentiable. To the future of the Cauchy horizon the solution is not unique, but depends on a free function (the null data coming out of the naked singularity). There is a unique continuation with a regular center (which is self-similar). All other self-similar continuations have a central timelike singularity with negative mass.

We show that existing low energy experiments, searching for the breaking of local Lorentz invariance, set bounds upon string theory inspired quantum gravity models that induce corrections to the propagation of fields. Using the standard observer Lorentz transformations in the D-particle recoil model we find $M>~1.2\times {10}^5{M}_P$ and $v<~2\times {10}^{-27}c$ for the mass and recoil speed of the D particle, respectively. These bounds are $\sim {10}^8$ times stronger than the latest astrophysical bounds. These results indicate that the stringy scenario for modified dispersion relations is as vulnerable to these types of tests as the loop quantum gravity schemes.

The first year Wilkinson Microwave Anisotropy Probe data favor primordial adiabatic fluctuation with a running spectral index with $n_s>1\mathrm{}$ on a large scale and $n_s<1\mathrm{}$ on a smaller scale. The model building of inflation that predicts perturbations with such a spectrum is a challenge, because most models predict fluctuations with either $n_s>1\mathrm{}$ (hybrid inflation) or $n_s<1\mathrm{}$ (new, chaotic, or topological inflation). We give a sensible particle physics model in supergravity that accommodates the desired running of the spectral index using double inflation.

In two recent papers we explored the modifications to primordial black hole physics when one moves to the simplest braneworld model, Randall-Sundrum type II. Both the evaporation law and the cosmological evolution of the population can be modified, and additionally accretion of energy from the background can be dominant over evaporation at high energies. In this paper we present a detailed study of how this impacts upon various astrophysical constraints, analyzing constraints from the present density, from the present high-energy photon background radiation, from distortion of the microwave background spectrum, and from processes affecting light element abundances both during and after nucleosynthesis. Typically, the constraints on the formation rate of primordial black holes weaken as compared to the standard cosmology if black hole accretion is unimportant at high energies, but can be strengthened in the case of efficient accretion.