We study a specific SUGRA model with nonuniversal gaugino masses as an alternative to the minimal SUGRA model in the context of supersymmetric dark matter. The lightest supersymmetric particle in this model turns out to be a Higgsino-dominated instead of a B-ino-dominated lightest neutralino. The thermal relic density of this Higgsino dark matter is somewhat lower than the cosmologically favored range, which means that it may be only a subdominant component of cold dark matter. Nonetheless, it predicts favorable rates of indirect detection, which can be seen in square-km-size neutrino telescopes.

We develop a renormalization group formalism for the compactified Randall-Sundrum scenario wherein the extra-dimensional radius serves as the scaling parameter. Couplings on the hidden brane scale as we move within local effective field theories with varying size of the warped extra dimension. We consider this RG approach applied to $U\left(1\right)\mathrm{}$ gauge theories and gravity. We use this method to derive a low energy effective theory.

We propose that the Euclidean bilocal collective field theory of critical large-N vector models provides a complete definition of the proposed dual theory of higher spin fields in anti–de Sitter spaces. We show how this bilocal field can be decomposed into an infinite number of even spin fields in one more dimension. The collective field has a nontrivial classical solution which leads to an $O\left(N\right)\mathrm{}$ thermodynamic entropy characteristic of the lower dimensional theory, as required by general considerations of holography. A subtle cancellation of the entropy coming from the bulk fields in one higher dimension with $O\left(1\right)\mathrm{}$ contributions from the classical solution ensures that the subleading terms in thermodynamic quantities are of the expected form. While the spin components of the collective field transform properly under dilatational, translational, and rotational isometries of AdS, special conformal transformations mix fields of different spins indicating a need for a nonlocal map between the two sets of fields. We discuss the nature of the propagating degrees of freedom through a Hamiltonian form of collective field theory and argue that nonsinglet states which are present in an Euclidean version are related to nontrivial backgrounds.

We consider multidimensional gravitational models with a nonlinear scalar curvature term and form fields in the action functional. In our scenario it is assumed that the higher dimensional spacetime undergoes a spontaneous compactification to a warped product manifold. Particular attention is paid to models with quadratic scalar curvature terms and a Freund-Rubin-like ansatz for solitonic form fields. It is shown that for certain parameter ranges the extra dimensions are stabilized. In particular, stabilization is possible for any sign of the internal space curvature, the bulk cosmological constant, and of the effective four-dimensional cosmological constant. Moreover, the effective cosmological constant can satisfy the observable limit on the dark energy density. Finally, we discuss the restrictions on the parameters of the considered nonlinear models and how they follow from the connection between the D-dimensional and the four-dimensional fundamental mass scales.

By combining data from seven cosmic microwave background experiments (including the latest WMAP results) with the Hubble parameter measurement from the Hubble space telescope and luminosity measurements of type Ia supernovae, we demonstrate the bounds on the dark energy equation of state $w_Q$ to be $-1.45<\mathrm{}{w}_Q<-0.74$ at the 95% confidence level. Although our limit on $w_Q$ is improved with respect to previous analyses, cosmological data do not rule out the possibility that the equation of state parameter $w_Q$ of the dark energy Q is less than $-1.$ We present a tracking model that ensures $w_Q<~-1$ at recent times and discuss the observational consequences.

We study the complete evolution of a flat and homogeneous universe dominated by tachyonic matter. We demonstrate the attractor behavior of tachyonic inflation using the Hamilton-Jacobi formalism. We also obtain analytical approximations for the trajectories of the tachyon field in different regions. The numerical calculation shows that an initial nonvanishing momentum does not prevent the onset of inflation. The slow-rolling solution is an attractor.

We conduct a systematic search for a viable string or M-theory cosmology, focusing on cosmologies that include an era of slow-roll inflation, after which the moduli are stabilized and the Universe is in a state with an acceptably small cosmological constant. We observe that the duality relations between different cosmological backgrounds of string or M-theory moduli space are greatly simplified, and that this simplification leads to a truncated moduli space within which possible cosmological solutions lie. We review some known challenges to four dimensional models in the “outer,” perturbative, region of moduli space, and use duality relations to extend them to models of all of the (compactified) perturbative string theories and 11D supergravity, including brane world models. We conclude that cosmologies restricted to the outer region are not viable, and that the most likely region of moduli space in which to find realistic cosmology is the “central,” nonperturbative region, with coupling and compact volume both of order unity, in string units.

We simulate propagation of cosmic ray nucleons above ${10}^{19}$ eV in scenarios where both the source distribution and magnetic fields within about 50 Mpc from us are obtained from an unconstrained large scale structure simulation. We find that a consistency of predicted sky distributions with current data above $4\times {10}^{19}$ eV requires magnetic fields of $\simeq 0.1\mu \mathrm{G}$ in our immediate environment, and a nearby source density of $\sim {10}^{-4}-{10}^{-3}{\mathrm{Mpc}}^{-3}.$ Radio galaxies could provide the required sources, but only if both high- and low-luminosity radio galaxies are very efficient cosmic ray accelerators. Moreover, at $\simeq {10}^{19}$ eV an additional isotropic flux component, presumably of cosmological origin, should dominate over the local flux component by about a factor of 3 in order to explain the observed isotropy. This argues against the scenario in which local astrophysical sources of cosmic rays above $\simeq {10}^{19}$ eV reside in a strongly magnetized $\left(B\simeq 0.1\mu \mathrm{G}\right)$ and structured intergalactic medium. Finally we discuss how future large scale full-sky detectors such as the Pierre Auger project will allow us to put much more stringent constraints on source and magnetic field distributions.

We compare in detail the results of simulations of electromagnetic showers in ice in the GeV–TeV energy range, using both the GEANT package and the ZHS Monte Carlo code, a code specifically designed to calculate coherent Čerenkov radio pulses from electromagnetic showers in dense media. The longitudinal and lateral profiles as well as the track lengths and excess projected track lengths are shown to agree below the $15\%$ level. We briefly comment on the negligible influence of the Landau-Pomerančuk-Migdal effect on the total shower track length. Our results are relevant for experiments exploiting the radio Čerenkov technique in dense media as well as for other detectors that rely on the Čerenkov effect in water or ice.

Motivated by the recent claim for gravitational lensing by a cosmic string, we reinvestigate the probability of finding such an event with upcoming wide-field surveys. If an observed lensing event is suspected to be due to a string, observations of the vicinity of the event in a circle of diameter L centered on the observed lens should reveal several additional lensing events. For a string located nearby $(z\lesssim 0.5),$ we find that observations in a region of size $\approx 1{\mathrm{arc}\mathrm{}\min }^2$ will see $\sim 100$ objects, of which $\sim 5$ would be lensed by the string, compared to $\sim 0.1$ lensed by conventional sources.

We address the tachyonic slepton problem of anomaly mediated supersymmetry breaking using Abelian D terms. We demonstrate that the most general extra $U\left(1\right)\mathrm{}$ symmetry that does not disrupt gauge coupling unification has a large set of possible charges that solves the problem. It is shown that previous studies in this direction that added both an extra hypercharge D-term and another D-term induced by $B-L$ symmetry (or similar) can be mapped into a single D-term of the general ancillary ${U\left(1\right)\mathrm{}}_{\mathrm{a}}.$ The ${U\left(1\right)\mathrm{}}_{\mathrm{a}}$ formalism enables identifying the sign of squark mass corrections which leads to an upper bound of the entire superpartner spectrum given knowledge of just one superpartner mass.

Recently WMAP has measured the cosmological parameters to a much greater accuracy. We analyze the implications of this more precise measurement for supersymmetric dark matter and for the direct detection of supersymmetry at accelerators. We consider MSUGRA including also the hyperbolic branch (HB) in the radiative breaking of the electroweak symmetry. On the part of the hyperbolic branch where the lightest neutralino is dominantly a Higgsino rather than being mostly a B-ino, the relic density constraints are satisfied by coannihilation with the next lightest neutralino and the light chargino. Including this branch the lightest neutralino mass satisfies $m_{{\chi }_1^0}<~1200\mathrm{GeV}$ for $\tan \beta <~50.$ Constraints of $\overrightarrow{b}s+\gamma ,$ of $g_{\mu }-2,$ and of $B_s^0\to {\mu }^{+}{\mu }^{-}$ are also analyzed. It is shown that the neutralino-proton cross section in each case will fall within the reach of dark matter experiments. The possibility for the direct detection of supersymmetry is discussed in the allowed regions of the parameter space consistent with WMAP constraints. A brief discussion of the hyperbolic branch and focus point region (HB/FP) is also given.

The extended supersymmetric standard model (ESSM), motivated on several grounds, introduces two vectorlike families $(16+\overline{16})$ of $\mathrm{SO}\mathrm{}\left(10\right)\mathrm{}$ with masses of the order of one TeV. It is noted that the successful predictions of prior work on fermion masses and mixings, based on the MSSM embedded in $\mathrm{SO}\mathrm{}\left(10\right),$ can be retained rather simply within the ESSM extension. These include an understanding of the smallness of $V_{\mathrm{cb}}\approx 0.04$ and the largeness of the ${\nu }_{\mu }-{\nu }_{\tau }$ oscillation angle, ${\sin }^{2}2{\theta }_{{\nu }_{\mu }{\nu }_{\tau }}^{\mathrm{osc}}\approx 1.$ We analyze the new contributions arising through the exchange of the vectorlike families of the ESSM to radiative processes including $\overrightarrow{\tau }\mu \gamma ,$ $\overrightarrow{\mu }e\gamma ,$ $\overrightarrow{b}s\gamma ,$ the EDM of the muon and the muon $\left(g-2\right).$ We show that the ESSM makes significant contributions especially to the decays $\overrightarrow{\tau }\mu \gamma$ and $\overrightarrow{\mu }e\gamma$ and simultaneously to muon $\left(g-2\right).$ For a large and plausible range of relevant parameters, we obtain $a_{\mu }^{\mathrm{ESSM}}\approx +\left(10\mathrm{}-40\right)\times {10}^{-10},$ with a correlated prediction that $\overrightarrow{\tau }\mu \gamma$ should be discovered with an improvement in its current limit by a factor of 3–20. The implications for $\overrightarrow{\mu }e\gamma$ are very similar. The muon EDM is within reach of the next generation experiments. Thus, the ESSM, with heavy leptons being lighter than about 1 TeV (say), can be probed effectively by radiative processes before a direct search for these vectorlike leptons and quarks is feasible at the CERN LHC.

We study the properties of the free energy of an infinitely heavy quark–antiquark pair in SU(2) gauge theory. By means of lattice Monte Carlo simulations we calculated the free energies in the singlet, triplet, and color averaged channels, both in the confinement and deconfinement phases. The singlet and triplet free energies are defined in the Coulomb gauge which is equivalent to their gauge invariant definitions recently introduced by Philipsen. We analyze the short and the long distance behavior, making comparisons with the zero temperature case. The temperature dependence of the electric screening mass is carefully investigated. The order of the deconfining transition is manifest in the results near $T_c$ and it allows a reliable test of a recently proposed method to renormalize the Polyakov loop.

Oscillation effects in $B^0\to K_S{D}^0$ and related processes are considered to determine $\delta \equiv \beta -\alpha +\pi =2\mathrm{}\beta +\gamma .$ We suggest that $D^0$ decays to $\mathrm{CP}$ eigenstates used in concert with inclusive $D^0$ decays provide a powerful method for determining $\delta$ cleanly. The $\mathrm{CP}$ asymmetry is expected to be $\lesssim 40\%$ for $D^0$ decays to non-$\mathrm{CP}$ eigenstates and $\lesssim 80\%$ for decays to $\mathrm{CP}$ eigenstates. This method can lead to a fairly accurate determination of $\delta$ with ${O(10\mathrm{}}^8-{10}^9)$ B mesons.

We consider a model with dilaton and twisted moduli fields, which is inspired by type I string models. The stabilization of their vacuum expectation values is studied. We find that the stabilization of the twisted moduli field has different aspects from dilaton stabilization.

To investigate the possibility of a ghost-antighost condensate, the coupled Dyson-Schwinger equations for the gluon and ghost propagators in Yang-Mills theories are derived in general covariant gauges, including ghost-antighost symmetric gauges. The infrared behavior of these two-point functions is studied in a bare-vertex truncation scheme which has proven to be successful in the Landau gauge. In all linear covariant gauges the same infrared behavior as in the Landau gauge is found: The gluon propagator is infrared-suppressed whereas the ghost propagator is infrared-enhanced. This infrared singular behavior provides an indication against a ghost-antighost condensate. In the ghost-antighost symmetric gauges we find that the infrared behavior of the gluon and ghost propagators cannot be determined when replacing all dressed vertices by bare ones. The question of a BRS invariant dimension-2 condensate remains to be further studied.

We examine the effects of boundary kinetic terms in the Randall-Sundrum model with gauge fields in the bulk. We derive the resulting gauge Kaluza-Klein (KK) state wave functions and their corresponding masses, as well as the KK gauge field couplings to boundary fermions, and find that they are modified in the presence of the boundary terms. In particular, for natural choices of the parameters, these fermionic couplings can be substantially suppressed compared to those in the conventional Randall-Sundrum scenario. This results in a significant relaxation of the bound on the lightest gauge KK mass obtained from precision electroweak data; we demonstrate that this bound can be as low as a few hundred GeV. Because of the relationship between the lightest gauge KK state and the electroweak scale in this model, this weakened constraint allows for the electroweak scale to be near a TeV in this minimal extension of the Randall-Sundrum model with bulk gauge fields, as opposed to the conventional scenario.

We discuss the motion of extended objects in a spacetime by considering a gravitational field created by these objects. We define multipole moments of the objects as a classification by the Lie group SO(3). Then, we construct an energy-momentum tensor for the objects and derive equations of motion from it. As a result, we reproduce the Papapetrou equations for a spinning particle. Furthermore, we will show that we can obtain more simple equations than the Papapetrou equations by changing the center-of-mass.