The SUSY hybrid inflation model is found to dissipate radiation during the inflationary period. Analysis is made of parameter regimes in which these dissipative effects are significant. The scalar spectral index, its running, and the tensor-scalar ratio are computed in the entire parameter range of the model. A clear prediction for strong dissipative warm inflation is found for $n_S-1\simeq 0.98$ and a low tensor-scalar ratio much below ${10}^{-6}$. The strong dissipative warm inflation regime also is found to have no $\eta$ problem and the field amplitude much below the Planck scale. As will be discussed, this has important theoretical implications in permitting a much wider variety of SUGRA extensions to the basic model.

Purely gravitational $pp$ waves in AdS backgrounds are described by the generalized Kaigorodov metrics, and they generically preserve $\frac{1}{4}$ of the maximum supersymmetry allowed by the AdS spacetimes. We obtain $\frac{1}{2}$ supersymmetric purely gravitational $pp$-wave solutions, in which the Kaigorodov component is set to zero. We construct $pp$ waves in AdS gauged supergravities supported by a vector field. We find that the solutions in $D=4$ and $D=5$ can then preserve $\frac{1}{2}$ of the supersymmetry. Like those in ungauged supergravities, the supernumerary supersymmetry imposes additional constraints on the harmonic function associated with the $pp$ waves. These new backgrounds provide interesting novel features of the supersymmetry enhancement for the dual conformal field theory in the infinite-momentum frame.

The evolution of weak discontinuity is investigated on horizons in the $n$-dimensional static solutions in the Einstein-Maxwell-scalar-$\Lambda$ system, including the Reissner-Nordström-(anti) de Sitter black hole. The analysis is essentially local and nonlinear. We find that the Cauchy horizon is unstable, whereas both the black hole event horizon and the cosmological event horizon are stable. This new instability, the so-called kink instability, of the Cauchy horizon is completely different from the well-known “infinite-blueshift” instability. The kink instability makes the analytic continuation beyond the Cauchy horizon unstable.

We study Einstein-Yang-Mills equations in the presence of a gravitating nontopological soliton field configuration consisting of a Higgs doublet, in Brans-Dicke and general scalar-tensor gravitational theories. The results of General Relativity are reproduced in the ${\omega }_{\mathrm{BD}},{\omega }_0\to \infty$ limit. The numerical solutions correspond to a soliton star with a non-Abelian gauge field. We study the effects of the coupling constant, the frequency of the Higgs field, and the Brans-Dicke field on the soliton parameters.

We consider threshold effects on neutrino masses and mixings in a recently proposed model for understanding large solar and atmospheric mixing angles using radiative magnification for the case of quasidegenerate neutrinos. We show that the magnitude of the threshold effects is sufficient to bring concordance between the predictions of this model and latest data from $\mathrm{KamLAND}$ and $\mathrm{SNO}$ on observations of neutrino oscillations.

We reconsider models of fermion masses and mixings based on a gauge anomalous horizontal $U(1)$ symmetry. In the simplest model with a single flavon field and horizontal charges of the same sign for all standard model fields, only very few charge assignements are allowed when all experimental data, including neutrino oscillation data, is taken into account. We show that a precise description of the observed fermion masses and mixing angles can easily be obtained by generating sets of the order one parameters left unconstrained by the $U(1)$ symmetry. The corresponding Yukawa matrices show several interesting features which may be important for flavor changing neutral currents and $CP$ violation effects in supersymmetric models.

We examine several assignments of spin and parity for the pentaquark ${\Theta }^{+}$ state ($J^P=1/2^{\pm },3/2^{\pm }$) in connection with known baryon resonances. Assuming that the ${\Theta }^{+}$ belongs to an antidecuplet representation which mixes with an octet, we calculate the mass spectra of the flavor partners of the ${\Theta }^{+}$ based on the SU(3) symmetry. The decay widths of the ${\Theta }^{+}$ and nucleon partners are analyzed for the consistency check of the mixing angle obtained from the masses. It is found that a suitable choice of the mixing angle successfully reproduces the observed masses of $\Theta (1540)$ and ${\Xi }_{3/2}(1860)$, when their spin and parity are assigned to be $J^P=3/2^{-}$, together with other $J^P=3/2^{-}$ resonances. The decay widths of $\Theta \to KN$, $N(1520)\to \pi N$, and $N(1700)\to \pi N$ are also reproduced simultaneously.

Color superconductors in which quarks of the same flavor form Cooper pairs are investigated. These Cooper pairs carry total spin one. A systematic group-theoretical classification of possible phases in a spin-one color superconductor is presented, revealing parallels and differences to the theory of superfluid ${}^3\mathrm{H}\mathrm{e}$. General expressions for the gap parameter, the critical temperature, and the pressure are derived and evaluated for several spin-one phases, with special emphasis on the angular structure of the gap equation. It is shown that the (transverse) color-spin-locked phase is expected to be the ground state.

We use Chiral Perturbation Theory to compute the nucleon mass-shift due to finite volume and temperature effects. Our results are valid up to next-to-leading-order in the “$ϵ$-régime” ($mL\sim m\beta \ll 1$) as well as in the “$p$-régime” ($mL\sim m\beta \gg 1$). Based on the two leading orders, we discuss the convergence of the expansion as a function of the lattice size and quark masses. This result can be used to extrapolate lattice results obtained from lattice sizes smaller than the pion cloud, avoiding the numerical simulation of physics under theoretical control. An extraction of the low-energy coefficient $c_3$ of the chiral Lagrangean from lattice simulations at small volumes and a “magic” ratio $\beta =1.22262L$ might be possible.

Since the $CP$ violation in the $B$ system has been investigated up to now only through processes related to the $B–\overline{B}$ mixing, urgently required is a new way of study for the $CP$ violation and establishing its origin in the $B$ system independent of the mixing process. In this work, we explore the exclusive $B^0\to {\rho }^0\gamma$ decay to obtain the time-dependent $CP$ asymmetry in the $b\to d$ decay process in the standard model and the supersymmetric model. We find that the complex $RL$ and $RR$ mass insertion to the squark sector in the minimal supersymmetric standard model can lead to a large $CP$ asymmetry in $B\to \rho \gamma$ decay through the gluino-squark diagrams, which is suppressed in the standard model and $B\to \rho \gamma$ may be a new window to study the new physics in the future.

We present a measurement of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}|$ based on a sample of about 53 700 ${\overline{B}}^0\to D^{*+}{\ell }^{-}{\overline{\nu }}_{\ell }$ decays observed by the BABAR detector. We obtain the branching fraction averaged over $\ell =e,\mu$, $\mathcal{B}({\overline{B}}^0\to D^{*+}{\ell }^{-}{\overline{\nu }}_{\ell })=\mathbf{(}4.90\pm 0.07{(\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}.)}_{-0.35}^{+0.36}(\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}.)\mathbf{)}\%$. We measure the differential decay rate as a function of $w$, the relativistic boost $\gamma$ of the $D^{*+}$ in the ${\overline{B}}^0$ rest frame. By extrapolating $d\Gamma /dw$ to the kinematic limit $w\to 1$, we extract the product of $|V_{cb}|$ and the axial form factor ${\mathcal{A}}_1(w=1)$. We combine this measurement with a lattice QCD calculation of ${\mathcal{A}}_1(w=1)$ to determine $|V_{cb}|=\mathbf{(}38.7\pm 0.3(\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}.)\pm 1.7{(\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}.)}_{-1.3}^{+1.5}(\mathrm{\text{theory}})\mathbf{)}\times {10}^{-3}.$

We use the weakly nonlocal hydrodynamics approach to obtain a dynamical equation for the peculiar velocity field in which the viscosity term is physically motivated. Based on some properties of the Ginzburg-Landau equation and the wave mechanics analog of hydrodynamics we find the nonlocal adhesion approximation taking into account the internal structures of the Zeldovich pancakes. If the internal structures correspond to significant mesoscopic fluctuations, viscosity is probably driven by a stochastic force and dynamics is given by the noisy Burgers equation.

We extend the analysis of Bonora et al. [hep-th/0409063] to the case of a constant electric field turned on the world volume and on a transverse direction of a D-brane. We show that time localization is still obtained by inverting the discrete eigenvalues of the lump solution. The lifetime of the unstable soliton is shown to depend on two free parameters: the $b$ parameter and the value of the electric field. As a by-product, we construct the normalized diagonal basis of the star algebra in the $B_{\mu \nu }$-field background.

We analyze the physics of nonlinear gravitational processes inside a spherical charged black hole perturbed by a self-gravitating massless scalar field. For this purpose we created an appropriate numerical code. Throughout the paper, in addition to investigation of the properties of the mathematical singularities where some curvature scalars are equal to infinity, we analyze the properties of the physical singularities where the Kretschmann curvature scalar is equal to the Planckian value. Using a homogeneous approximation we analyze the properties of the spacetime near a spacelike singularity in spacetimes influenced by different matter contents, namely, a scalar field, pressureless dust and matter with ultrarelativistic isotropic pressure. We also carry out full nonlinear analyses of the scalar field and geometry of spacetime inside black holes by means of an appropriate numerical code with adaptive mesh refinement capabilities. We use this code to investigate the nonlinear effects of gravitational focusing, mass inflation, matter squeeze, and these effects dependence on the initial boundary conditions. It is demonstrated that the position of the physical singularity inside a black hole is quite different from the positions of the mathematical singularities. In the case of the existence of a strong outgoing flux of the scalar field inside a black hole it is possible to have the existence of two null singularities and one central $r=0$ singularity simultaneously.

We present the first relativistic calculations of the final phase of inspiral of a binary system consisting of two stars built predominantly of strange quark matter (strange quark stars). We study the precoalescing stage within the Isenberg-Wilson-Mathews approximation of general relativity using a multidomain spectral method. A hydrodynamical treatment is performed under the assumption that the flow is either rigidly rotating or irrotational, taking into account the finite density at the stellar surface—a distinctive feature with respect to the neutron star case. The gravitational-radiation driven evolution of the binary system is approximated by a sequence of quasiequilibrium configurations at fixed baryon number and decreasing separation. We find that the innermost stable circular orbit (ISCO) is given by an orbital instability both for synchronized and irrotational systems. This contrasts with neutron stars for which the ISCO is given by the mass-shedding limit in the irrotational case. The gravitational wave frequency at the ISCO, which marks the end of the inspiral phase, is found to be $\sim 1400\mathrm{H}\mathrm{z}$ for two irrotational $1.35{\mathrm{M}}_{\odot }$ strange stars and for the MIT bag model of strange matter with massless quarks and a bag constant $B=60\mathrm{M}\mathrm{e}\mathrm{V}\mathrm{f}{\mathrm{m}}^{-3}$. Detailed comparisons with binary neutrons star models, as well as with third order post-Newtonian point-mass binaries are given.

We investigate in detail recent suggestions that codimension-two braneworlds in six-dimensional supergravity might circumvent Weinberg’s no-go theorem for self-tuning of the cosmological constant. The branes are given finite thickness in order to regularize mild singularities in their vicinity, and we allow them to have an arbitrary equation of state. We study perturbatively the time evolution of the solutions by solving the equations of motion linearized around a static background. Even allowing for the most general possibility of warping and nonconical singularities, the geometry does not relax to a static solution when the brane stress energies are perturbed. Rather, both the internal and external geometries become time dependent, and the system does not exhibit any self-tuning behavior.

We investigate cosmic-ray antiprotons emitted from the galactic primordial black holes (PBHs) in the Randall-Sundrum type-2 braneworld. The recent results of the Balloon-borne Experiment with a Superconducting Spectrometer (BESS) antiproton observation imply the existence of exotic primary sub-GeV antiprotons, one of whose most probable origin is PBHs in our Galaxy. We show that the magnitude of antiproton flux from PBHs in the Randall-Sundrum braneworld is proportional to negative power of the anti–de Sitter radius and immediately find that a large extra dimension can relax upper limits on the abundance of the galactic PBHs. If actually there are more PBHs than the known upper limit obtained in the pure 4D case, they set a lower bound on the size of the extra dimension above at least ${10}^{20}$ times 4D Planck length to avoid inconsistency. On completion of the numerical studies, we show that these constraints on the AdS radius are comparable to those obtained from the diffuse photon background by some of the authors in the previous paper. Moreover, in the low accretion rate case, only antiprotons can constrain the braneworld. We show that we will detect signatures of the braneworld as a difference between the flux of the antiprotons predicted in 4D and 5D by future observations in sub-GeV region with a few percent precision.

We show that hadronic matrix elements can be extracted from lattice simulations with background fields that arise from operator exponentiation. Importantly, flavor-singlet matrix elements can be evaluated without requiring the computation of disconnected diagrams, thus facilitating a calculation of the quark contribution to the spin of the proton and the singlet axial coupling, $g_A^0$. In the two-nucleon sector, a background field approach will allow calculation of the magnetic and quadrupole moments of the deuteron and an investigation of the EMC effect directly from lattice QCD. Matrix elements between states of differing momenta are also analyzed in the presence of background fields.