Causality on the gravity side of the AdS/CFT correspondence restricts motion on the moduli space of the $\mathcal{N}=4$ super Yang-Mills theory by imposing a speed limit on how fast the scalar field may roll. This effect can be traced to higher-derivative operators arising from integrating out light degrees of freedom near the origin. In the strong coupling limit of the theory, the dynamics is well approximated by the Dirac-Born-Infeld Lagrangian for a probe D3-brane moving toward the horizon of the AdS Poincaré patch, combined with an estimate of the (ultimately suppressed) rate of particle and string production in the system. We analyze the motion of a rolling scalar field explicitly in the strong coupling regime of the field theory and extend the analysis to cosmological systems obtained by coupling this type of field theory to four-dimensional gravity. This leads to a mechanism for slow roll inflation for a massive scalar at sub-Planckian vacuum expectation value without need for a flat potential (realizing a version of k inflation in a microphysical framework). It also leads to a variety of novel Friedman-Roberston-Walker cosmologies, some of which are related to those obtained with tachyon matter.

We recalculate masses and widths of antidecuplet baryons in the case of positive parity from chiral soliton models, provided that the member ${\Xi }_{3/2}$ of the antidecuplet has a mass 1.86 GeV, as reported recently. Calculations show that there are no convincing candidates for the nonexotic members of the antidecuplet available in the baryon listings. Up to the leading order of $m_s$ and $1/N_c$, the width formula for the decay of the antidecuplet baryons to the octet depends only on $\mathrm{S}\mathrm{U}(3)$ symmetry model independently, except the coupling constant. Similarly, we give a width formula for the decay of negative parity baryons belonging to certain $\mathrm{S}\mathrm{U}(3)$ baryon multiplets by pure symmetry consideration. By this formula, we find that if we have an antidecuplet with negative parity and that the masses are the same as those given by chiral soltion models, the identification of $N(1650)$ as $N_{\overline{10}}$ are inconsistent with experiments for $N(1650)\to N\pi$ while the widths agree with other two decay channels involving strangeness. And $\Sigma (1750)$ seems to be a reasonable candidate for ${\Sigma }_{\overline{10}}$.

Weak radiative baryonic $B$ decays $B\to {\mathbf{B}}_1\overline{{\mathbf{B}}_2}\gamma$ are studied under the assumption of the short-distance $b\to s\gamma$ electromagnetic penguin transition dominance. The relations among the decay rates of various decay modes are derived.

We propose the use of $B^{\pm }\to \stackrel{(-)}{D^{**0}}{K}^{\pm }$ decay modes for a theoretically clean determination of the weak phase $\gamma$. The self-tagging decays of the neutral $D^{**}$ mesons make a measurement of the $b\to u\overline{c}s$ amplitude feasible. This overcomes the problem with the Gronau-London-Wyler proposal. Even an upper limit on the $\mathcal{B}(B^{-}\to {\overline{D}}^{**0}{K}^{-})$ will place an assumption free, lower bound on $\gamma$.

To explain the observed neutrino masses through the seesaw mechanism, a supersymmetric generalization of the standard model should include heavy right-handed neutrino supermultiplets. Then the neutrino Yukawa couplings can induce $CP$ violation in the lepton sector. In this paper, we compute the contribution of these $CP$ violating terms to lepton electric dipole moments. We introduce a new formalism that makes use of supersymmetry to expose the Glashow-Iliopoulos-Maiani cancellations. In the region of small $\tan \beta$, we find a different result from that given previously by Ellis, Hisano, Raidal, and Shimizu. We confirm the structure found by this group, but with a much smaller overall coefficient. In the region of large $\tan \beta$, we recompute the leading term that has been identified by Masina and confirm her result up to minor factors. We discuss the implications of these results for constraints on the $Y_{\nu }$.

The behavior of the vector Adler function at spacelike momenta is studied in the framework of a covariant chiral quark model with instantonlike quark-quark interaction. This function describes the transition between the high-energy asymptotically free region of almost massless current quarks to the low-energy hadronized regime with massive constituent quarks. The model reproduces the Adler function and $V-A$ correlator extracted from the ALEPH and OPAL data on hadronic $\tau$ lepton decays, transformed into the Euclidean domain via dispersion relations. The leading order contribution from the hadronic part of the photon vacuum polarization to the anomalous magnetic moment of the muon, $a_{\mu }^{\mathrm{h}\mathrm{v}\mathrm{p}(1)}$, is estimated.

We study power corrections to a recently introduced family of event shapes, the class of angularities, within the formalism of dressed gluon exponentiation (DGE). We find that the universal scaling rule for the leading power corrections deduced from resummation also holds when taking renormalon enhancements into account. The scaling is due to boost invariance of eikonal dynamics in the two-jet limit, which we recover in the context of DGE. Furthermore, dressed gluon exponentiation provides an ansatz for nonleading power corrections that violate the scaling. These nonleading corrections are further suppressed by noninteger powers of the hard scale.

We analyze various possible interpretations of the narrow state $D_{sJ}(2632)$ which lies 100 MeV above threshold. This interesting state decays mainly into $D_s\eta$ instead of $D^0{K}^{+}$. If this relative branching ratio is further confirmed by other experimental groups, we point out that the identification of $D_{sJ}(2632)$ either as a $c\overline{s}$ state or more generally as a $\overline{\mathbf{3}}$ state in the $\mathrm{S}\mathrm{U}(3{)}_F$ representation is probably problematic. Instead, such an anomalous decay pattern strongly indicates $D_{sJ}(2632)$ is a four-quark state in the $\mathrm{S}\mathrm{U}(3{)}_F$ $\mathbf{15}$ representation with the quark content $\frac{1}{2\sqrt{2}}(ds\overline{d}+sd\overline{d}+su\overline{u}+us\overline{u}-2ss\overline{s})\overline{c}$. We discuss its partners in the same multiplet and the similar four-quark states composed of a bottom quark $B_{sJ}^0(5832)$. Experimental searches of other members especially those exotic ones are strongly called for.

We study constraints on new physics from the recent measurement of $\mathrm{B}\mathrm{r}(K^{+}\to {\pi }^{+}\nu \overline{\nu })$ by the E787 and E949 Collaborations. In our analysis, we consider two models of new physics: (a) extra down-type singlet quark model and (b) $R$-parity violating minimal supersymmetric standard model. We find that $K^{+}\to {\pi }^{+}\nu \overline{\nu }$ along with other processes such as $K_L\to {\mu }^{+}{\mu }^{-},{ϵ}^{\prime }/ϵ$ provide useful bounds on the parameter $U_{sd}$, characterizing the off-diagonal $Z-d-\overline{s}$ coupling of model (a). The bounds on $\mathrm{R}\mathrm{e}(U_{sd})$ from $(K_L\to {\mu }^{+}{\mu }^{-}{)}_{\mathrm{S}\mathrm{D}}$ and $\mathrm{I}\mathrm{m}(U_{sd})$ from ${ϵ}^{\prime }/ϵ$ are so tight that the branching ratio of $K^{+}\to {\pi }^{+}\nu \overline{\nu }$ can exceed the standard model value by at most a factor of 2. For model (b), we also obtain stringent bounds on certain combinations of the product of two ${\lambda }_{ijk}^{\prime }$ couplings originating from $L$ number-violating operator $L_i{Q}_j{D}_k^c$ using $K^{+}\to {\pi }^{+}\nu \overline{\nu }$ and $K_L\to {\mu }^{+}{\mu }^{-}$ processes. Even with the stringent constraints on $U_{sd}$ [in model (a)] and on products of two $\mathrm{R̸}$ couplings [model (b)], we find that the branching ratio $\mathcal{B}(K_L\to {\pi }^0\nu \overline{\nu })$ can be substantially different in both of the above models from those predicted in the standard model.

We perform a next-to-leading order (NLO) QCD analysis of deep-inelastic scattering data, in which we account for absorptive corrections. These corrections are determined from a simultaneous analysis of diffractive deep-inelastic data. The absorptive effects are found to enhance the size of the gluon distribution at small $x$, such that a negative input gluon distribution at $Q^2=1{\mathrm{G}\mathrm{e}\mathrm{V}}^2$ is no longer required. We discuss the problem that the gluon distribution is valence-like at low scales, whereas the sea quark distribution grows with decreasing $x$. Our study hints at the possible importance of power corrections for $Q^2\simeq 1-2{\mathrm{G}\mathrm{e}\mathrm{V}}^2$.

We investigate a possible unified theory of all interactions which is based only on fundamental spinor fields. The vielbein and metric arise as composite objects. The effective quantum gravitational theory can lead to a modification of Einstein's equations due to the lack of local Lorentz symmetry. We explore the generalized gravity with global instead of local Lorentz symmetry in first order of a systematic derivative expansion. At this level diffeomorphisms and global Lorentz symmetry allow for two new invariants in the gravitational effective action. The one which arises in the one loop approximation to spinor gravity is consistent with all present tests of general relativity and cosmology. This shows that local Lorentz symmetry is tested only very partially by present observations. In contrast, the second possible new coupling is severely restricted by present solar system observations.

We propose a new formulation for $3+1$ numerical relativity, based on a constrained scheme and a generalization of Dirac gauge to spherical coordinates. This is made possible thanks to the introduction of a flat 3-metric on the spatial hypersurfaces $t=\mathrm{c}\mathrm{o}\mathrm{n}\mathrm{s}\mathrm{t}$, which corresponds to the asymptotic structure of the physical 3-metric induced by the spacetime metric. Thanks to the joint use of Dirac gauge, maximal slicing and spherical components of tensor fields, the ten Einstein equations are reduced to a system of five quasilinear elliptic equations (including the Hamiltonian and momentum constraints) coupled to two quasilinear scalar wave equations. The remaining 3 degrees of freedom are fixed by the Dirac gauge. Indeed this gauge allows a direct computation of the spherical components of the conformal metric from the two scalar potentials which obey the wave equations. We present some numerical evolution of 3D gravitational wave spacetimes which demonstrates the stability of the proposed scheme.

In this paper, we present several gravitational wave solutions in ${\mathrm{A}\mathrm{d}\mathrm{S}}_5\times S^5$ string backgrounds, as well as in ${\mathrm{A}\mathrm{d}\mathrm{S}}_7\times S^4$ and ${\mathrm{A}\mathrm{d}\mathrm{S}}_4\times S^7$ backgrounds in M theory, generalizing the results of Phys. Lett. B 594, 368 (2004).. In each case, we present the general form of such solutions and give explicit examples, preserving certain amount of supersymmetry, by taking limits on known Bogomol'nyi-Prasad-Sommerfield D3 and M2, M5-brane solutions in $pp$-wave backgrounds. A key feature of our examples is the possibility of a wider variety of wave profiles, than in pure gravity and string/M-theory examples known earlier, coming from the presence of various $p$-form field strengths appearing in the gravitational wave structure.

The gravitational waveforms emitted during the adiabatic inspiral of precessing binaries with two spinning compact bodies of comparable masses, evaluated within the post-Newtonian approximation, can be reproduced rather accurately by the waveforms obtained by setting one of the two spins to zero, at least for the purpose of detection by ground-based gravitational-wave interferometers. Here we propose to use this quasiphysical family of single-spin templates to search for the signals emitted by double-spin precessing binaries, and we find that its signal-matching performance is satisfactory for source masses $(m_1,m_2)\in [3,15]M_{\odot }\times [3,15]M_{\odot }$. For this mass range, using the LIGO-I design sensitivity, we estimate that the number of templates required to yield a minimum match of 0.97 is $\sim 320000$. We discuss also the accuracy to which the single-spin template family can be used to estimate the parameters of the original double-spin precessing binaries.

We reconsider the toy model studied by Gordon and Turok of a spatially closed Friedmann-Lemaître universe, driven by a massive scalar field, which deflates quasiexponentially, bounces, and then enters a period of standard inflation. We find that the equations for the matter density perturbations can be solved analytically, at least at lowest order in some “slow-roll” parameter. We can therefore give, in that limit, the explicit spectrum of the postbounce perturbations in terms of their prebounce initial spectrum. Our result is twofold. If the prebounce growing and decaying modes are of the same order of magnitude at the bounce, then the spectrum of the prebounce growing mode is carried over to the postbounce decaying mode. On the other hand, if, more likely, the prebounce growing mode dominates, then resolution at next order indicates that its spectrum is nicely carried over, with reduced amplitude, to the postbounce growing mode.

Alternative gravitational theories described by Lagrangians depending on general functions of the Ricci scalar have been proven to give coherent theoretical models to describe the experimental evidence of the acceleration of the Universe at present time. In this paper we proceed further in this analysis of cosmological applications of alternative gravitational theories depending on (other) curvature invariants. We introduce Ricci squared Lagrangians in minimal interaction with matter (perfect fluid); we find modified Einstein equations and consequently modified Friedmann equations in the Palatini formalism. It is striking that both Ricci scalar and Ricci squared theories are described in the same mathematical framework and both the generalized Einstein equations and generalized Friedmann equations have the same structure. In the framework of the cosmological principle, without the introduction of exotic forms of dark energy, we thus obtain modified equations providing values of $w_{\mathrm{e}\mathrm{f}\mathrm{f}}<-1$ in accordance with the experimental data. The spacetime bi-metric structure plays a fundamental role in the physical interpretation of results and gives them a clear and very rich geometrical interpretation.

We develop a new method to reconstruct the power spectrum of primordial curvature perturbations $P(k)$ by using both the temperature and polarization spectra of the cosmic microwave background (CMB). We test this method using several mock primordial spectra having nontrivial features including the one with an oscillatory component, and find that the spectrum can be reconstructed with a few percent accuracy by an iterative procedure in an ideal situation in which there is no observational error in the CMB data. In particular, although the previous “cosmic inversion” method, which used only the temperature fluctuations, suffered from large numerical errors around some specific values of $k$ that correspond to nodes in a transfer function, these errors are found to disappear almost completely in the new method.

We study the infrared part of the spectrum for UV-filtered staggered Dirac operators and compare them to the overlap counterpart. With sufficient filtering and at small enough lattice spacing the staggered spectra manage to “mimic” the overlap version. They show a 4-fold near degeneracy, and a clear separation between would-be zero modes and nonzero modes. This suggests an approximate index theorem for filtered staggered fermions and a correct sensitivity to the topology of QCD. Moreover, it supports square-rooting the staggered determinant to obtain dynamical ensembles with $N_f=2$.

By employing the QCD factorization approach, we calculate the new physics contributions to the branching radios of the two-body charmless $B\to PP$ decays in the framework of the minimal supergravity (mSUGRA) model. Within the considered parameter space, we find that (a) the supersymmetric (SUSY) corrections to the Wilson coefficients $C_k$ ($k=3-6$) are very small and can be neglected safely, but the leading order SUSY contributions to $C_{7\gamma }(M_W)$ and $C_{8g}(M_W)$ can be rather large and even change the sign of the corresponding coefficients in the standard model; (b) the possible SUSY contributions to those penguin-dominated decays in mSUGRA model can be as large as 30%-50%; (c) for the well measured $B\to K\pi$ decays, the significant SUSY contributions play an important role in improving the consistency of the theoretical predictions with the data; (d) for $B\to K{\eta }^{\prime }$ decays, the theoretical predictions of the corresponding branching ratios become consistent with the data within 1 standard deviation after the inclusion of the large SUSY contributions in the mSUGRA model.

We investigate the electromagnetic form factors of the $\rho$ meson in light cone QCD sum rules. We find that the ratio of the magnetic and charge form factors is larger than 2 at all values of $Q^2$, ($Q^2\ge 0.5{\mathrm{G}\mathrm{e}\mathrm{V}}^2$). The values of the individual form factors at fixed values of $Q^2$ predicted by the light cone QCD sum rules are quite different compared to the results of other approaches. These results can be checked in the future, when more precise data on $\rho$ meson form factors is available.