The recent search for a stochastic background of gravitational waves with LIGO interferometers has produced a new upper bound on the amplitude of this background in the 100 Hz region. We investigate the implications of the current and future LIGO results on pre-big-bang models of the early Universe, determining the exclusion regions in the parameter space of the minimal pre-big-bang scenario. Although the current LIGO reach is still weaker than the indirect bound from big bang nucleosynthesis, future runs by LIGO, in the coming year, and by Advanced LIGO ($\sim 2009$) should further constrain the parameter space, and in some parts surpass the Big Bang nucleosynthesis bound. It will be more difficult to constrain the parameter space in nonminimal pre-big bang models, which are characterized by multiple cosmological phases in the yet not well understood stringy phase, and where the higher-order curvature and/or quantum-loop corrections in the string effective action should be included.

Following previous work, we identify a symmetry $S_{\mathrm{nat}}$ that generalizes the concept of custodial symmetry, keeping under control deviations from the standard model (SM). To realize $S_{\mathrm{nat}}$ linearly, the space of gauge fields has to be extended. Covariant constraints formulated in terms of spurions reduce $S_{\mathrm{nat}}$ back to $\mathrm{SU}(2{)}_L\times \mathrm{U}(1{)}_Y$. This allows for a covariant introduction of explicit $S_{\mathrm{nat}}$-breaking parameters. We assume that $S_{\mathrm{nat}}$ is at play in a theory of electroweak symmetry-breaking without a light Higgs particle. We describe some consequences of this assumption, using a nondecoupling effective theory in which the loop expansion procedure is based on both momentum and spurion power-counting, as in chiral perturbation theory. A hierarchy of lepton-number violating effects follows. Leading corrections to the SM are nonoblique. The effective theory includes stable light right-handed neutrinos, with an unbroken ${\mathbb{Z}}_2$ symmetry forbidding neutrino Dirac masses. ${\nu }_R$ contribution to dark matter places bounds on their masses.

We study the stau lifetime in a scenario with the LSP taken to be a neutralino and the NLSP being a stau, based on the minimal supersymmetric Standard Model. The mass difference between the LSP and NLSP, $\delta m$, must satisfy $\delta m/m_{\tilde{\chi }}\sim$ a few % or less for coannihilation to occur, where $m_{\tilde{\chi }}$ is the neutralino mass. We calculate the stau lifetime from the decay modes $\tilde{\tau }\to \tilde{\chi }\tau$, $\tilde{\chi }{\nu }_{\tau }\pi$, and $\tilde{\chi }{\nu }_{\tau }\mu (e){\nu }_{\mu (e)}$ and discuss its dependence on various parameters. We find that the lifetime is in the range ${10}^{-22}–{10}^{16}\sec $ for ${10}^{-2}\le \delta m\le 10\mathrm{GeV}$. We also discuss the connection with lepton flavor violation if there is mixing between sleptons.

We consider a scenario in which the discrete weak symmetry between quarks and leptons is extended to the weak force by introducing exotic partners. We conjecture that there exists a hidden discrete symmetry $\tilde{\mathrm{P}}$, defining a ${\mathbf{Z}}_{\mathbf{2}}$ group, between standard and exotic quarks and leptons. The unified model $\mathrm{SU}(3{)}_q\times \mathrm{SU}(3{)}_{\tilde{q}}\times \mathrm{SU}(2{)}_{q\tilde{\ell }}\times \mathrm{SU}(2{)}_{\tilde{q}\ell }\times \mathrm{U}(1{)}_Y\times \tilde{\mathrm{P}}$ is discussed, where the unifying discrete symmetry extends over particles and forces. It is shown that the lighter neutral and charged weak bosons generated upon spontaneous symmetry breaking have the same properties as those of the standard model. Cabbibo-Kobayashi-Maskawa unitarity is used to set a mass of order 2.8 TeV for the nonstandard weak bosons, which do not exhibit quark-lepton universality. A grand unified theory of $(\mathrm{GUT}{)}_{q\tilde{\ell }}\times (\mathrm{GUT}{)}_{\tilde{q}\ell }\times \tilde{\mathrm{P}}$ type, with decay of exotic matter into standard matter and no decay of the ordinary nucleon, is put forward.

We present a study of the neutron electric dipole moment (${\overrightarrow{d}}_N$) within the framework of lattice QCD with two flavors of dynamical light quarks. The dipole moment is sensitive to the topological structure of the gauge fields, and accuracy can only be achieved by using dynamical, or sea quark, calculations. However, the topological charge evolves slowly in these calculations, leading to a relatively large uncertainty in ${\overrightarrow{d}}_N$. It is shown, using quenched configurations, that a better sampling of the charge distribution reduces this problem, but because the $CP$ even part of the fermion determinant is absent, both the topological charge distribution and ${\overrightarrow{d}}_N$ are pathological in the chiral limit. We discuss the statistical and systematic uncertainties arising from the topological charge distribution and unphysical size of the quark mass in our calculations and prospects for eliminating them. Our calculations employ the RBC collaboration two flavor domain wall fermion and DBW2 gauge action lattices with inverse lattice spacing $a^{-1}\approx 1.7\mathrm{GeV}$, physical volume $V\approx (2\mathrm{fm}{)}^3$, and light quark mass roughly equal to the strange quark mass ($m_{\mathrm{sea}}=0.03$ and 0.04). We determine a value of the electric dipole moment that is zero within (statistical) errors, from which we obtain the bound $|{\overrightarrow{d}}_N|\lesssim 0.02e\mathrm{\text{−}}\theta \mathrm{\text{−}}\mathrm{fm}$. Satisfactory results for the magnetic and electric form factors of the proton and neutron are also obtained and presented.

We present a determination of the strange quark mass for two flavors ($n_f=2$) of light dynamical quarks using the axial Ward identity. The calculations are performed on the lattice using $O(a)$ improved Wilson fermions and include a fully nonperturbative determination of the renormalization constant. In the continuum limit we find $m_s^{\overline{\mathrm{MS}}}(2\mathrm{GeV})=111(6)(4)(6)\mathrm{MeV}$, using the force scale $r_0=0.467\mathrm{fm}$, where the first error is statistical, the second and third are systematic due to the fit and scale uncertainties, respectively. Results are also presented for the light quark mass and the chiral condensate. The corresponding results are also given for $r_0=0.5\mathrm{fm}$.

The chromomagnetic interaction, with proper account for flavor-symmetry breaking, is shown to explain the mass and coupling properties of the X(3872) resonance as a $J^{PC}=1^{++}$ state consisting of a heavy quark-antiquark pair and a light one. It is crucial to introduce all the spin-color configurations compatible with these quantum numbers and diagonalize the chromomagnetic interaction in this basis. This approach thus differs from the molecular picture $\mathrm{D}{\overline{\mathrm{D}}}^{*}$ and from the diquark–anti-diquark picture.

We estimate pionic decay widths of the narrow charm-strange resonances $D_{sj}(2317)$ and $D_{sj}(2460)$ using the ${}^{3}P_0$ model. Their one-pion decays occur through $\eta -{\pi }^0$ mixing while the two-pion decays of $D_{sj}(2460)$ occur through the virtual $f_0(980)$ meson. The mixing between ${}^{3}P_0$ and ${}^{1}P_1$ states enhances the single-pion decay width of $D_{sj}(2460)$ and suppresses its double-pion decay width significantly. As a byproduct, we also calculate pionic decay widths of $B_{sj}(5765)$, $B_{sj}(5765)$ mesons in the $(0^{+},1^{+})$ heavy doublet.

We present a quantitative study on sensitivities to the top-decay anomalous couplings, taking into account realistic experimental conditions expected at Tevatron and LHC. A double angular distribution of $W$ and charged lepton in the top-decay is analyzed, using $t\overline{t}$ events in the $\mathrm{\text{leptons}}+\mathrm{\text{jets}}$ channel. In order to improve sensitivities to the anomalous couplings, we apply two techniques: (i) We use a likelihood fitting method for full kinematical reconstruction of each top event. (ii) We develop a new effective spin reconstruction method for leptonically-decayed top quarks; this method does not require spin information of the antitop side. For simplicity, we neglect couplings of right-handed bottom quark as well as $CP$ violating couplings. The 95% C.L. estimated bound on a ratio of anomalous couplings reads $-0.81<f_2/f_1<-0.70$, $-0.12<f_2/f_1<0.14$ using 1000 reconstructed top events at Tevatron, while $-0.74<f_2/f_1<-0.72$, $-0.01<f_2/f_1<0.01$ is expected with 100 k reconstructed top events at LHC, where only statistical errors are taken into account. A two-fold ambiguity in the allowed range remains when the number of events exceeds a few hundred.

Using chiral symmetry we investigate the leading SU(3) violation in the complete set of quark twist-3 light-cone distribution functions of the pion, kaon, and eta, including the two-parton distributions ${\varphi }_M^p$, ${\varphi }_M^{\sigma }$, and the three-parton distribution ${\varphi }_M^3$. It is shown that terms nonanalytic in the quark masses do not affect the shape, and only appear in the normalization constants. Predictive power is retained including the leading analytic $m_q$ operators. With the symmetry violating corrections we derive useful model-independent relations between ${\varphi }_{\pi }^{p,\sigma ,3}$, ${\varphi }_{\eta }^{p,\sigma ,3}$, ${\varphi }_{K^{+},K^0}^{p,\sigma ,3}$, and ${\varphi }_{{\overline{K}}^0,K^{-}}^{p,\sigma ,3}$. We also comment on the calculations of the moments of these distributions using lattice QCD and light-cone sum rules.

We study the operator product expansion (OPE) and quark-hadron duality for 2- and 3-point correlators of the axial ($A$) and pseudoscalar ($P$) currents of the light quarks. In the chiral limit these correlators are often dominated by nonperturbative power corrections leading to subtleties of quark-hadron duality relations and of the extraction of properties of light pseudoscalars. For the 2-point correlators, we show the sum rule for $⟨PP⟩$ to be sensitive to the excited light pseudoscalar. For the 3-point correlators, we derive the Ward identities which provide the normalization of the pion electromagnetic form factor at zero momentum transfer. For large momentum transfer, we demonstrate the way the correct behavior of the pion form factor in agreement with perturbative QCD emerges from condensate terms in the OPE for the $⟨PVP⟩$ and $⟨AVP⟩$ correlators. The local-duality sum rule for $⟨AVA⟩$ is shown to lead to the pion form factor with the required properties for all values of the momentum transfer.

Sensitivities to ${sin}^{2}2{\theta }_{13}$ without statistical errors (“systematic limit”) are investigated in neutrino oscillation experiments with multiple reactors. Using an analytical approach, we show that the systematic limit on ${sin}^{2}2{\theta }_{13}$ is dominated by the uncorrelated systematic error ${\sigma }_{\mathrm{u}}$ of the detector. Even in an experiment with multidetectors and multireactors, it turns out that most of the systematic errors including the one due to the nature of multiple sources is canceled as in the case with a single reactor plus two detectors, if the near detectors are placed suitably. The case of the KASKA plan (7 reactors and 3 detectors) is investigated in detail, and it is explicitly shown that it does not suffer from the extra uncertainty due to multiple reactors.

We present an evolution equation for the Bjorken $x$ dependence of diffractive dissociation on hadrons and nuclei at high energies. We extend the formulation of Kovchegov and Levin by relaxing the factorization assumption used there. The formulation is based on a technique used by Weigert to describe interjet energy flow. The method can be naturally extended to other exclusive observables.

According to perturbation theory, a thin piston in a thin-walled semi-infinite cylinder closed at its head, both weakly reflecting dielectrics, experiences a force which is directed towards the cylinder head at small separations $a$, but which changes sign as $a$ rises. By contrast, for thick enough material the force remains attractive for all $a$ (as it does for perfect reflection, according to the recent paper by Hertzberg et al. [M. P. Hertzberg, R. L. Jaffe, M. Kardar, and A. Scardicchio, Phys. Rev. Lett. 95, 250402 (2005)]).

We show that the real massive Klein-Gordon theory admits a description in terms of states on various timelike hypersurfaces and amplitudes associated with regions bounded by them. This realizes crucial elements of the general boundary framework for quantum field theory. The hypersurfaces considered are hyperplanes on the one hand and timelike hypercylinders on the other hand. The latter lead to the first explicit examples of amplitudes associated with finite regions of space, and admit no standard description in terms of “initial” and “final” states. We demonstrate a generalized probability interpretation in this example, going beyond the applicability of standard quantum mechanics.

In this paper, we study the gravitational collapse of null dust in cylindrically symmetric spacetime. The naked singularity necessarily forms at the symmetry axis. We consider the situation in which null dust is emitted again from the naked singularity formed by the collapsed null dust and investigate the backreaction by this emission for the naked singularity. We show a very peculiar but physically important case in which the same amount of null dust as that of the collapsed one is emitted from the naked singularity as soon as the ingoing null dust hits the symmetry axis and forms the naked singularity. In this case, although this naked singularity satisfies the strong curvature condition by Królak (limiting focusing condition), geodesics which hit the singularity can be extended uniquely across the singularity. Therefore, we may say that the collapsing null dust passes through the singularity formed by itself and then leaves for infinity. Finally, the singularity completely disappears and the flat spacetime remains.

We obtain a global embedding of the surface of a rapidly rotating Kerr-Newman black hole in an Euclidean 4-dimensional space.

We first reconstruct the conserved (Abbott-Deser) charges in the spin-connection formalism of gravity for asymptotically (Anti)-de Sitter spaces, and then compute the masses of the $AdS$ soliton and the recently found Eguchi-Hanson solitons in generic odd dimensions, unlike the previous result obtained for only five dimensions. These solutions have negative masses compared to the global $AdS$ or $AdS/Z_p$ spacetimes. As a separate note, we also compute the masses of the recent even dimensional Taub-NUT-Reissner-Nordström metrics.

Vacuum expectation value of the energy-momentum tensor and the vacuum interaction forces are evaluated for a massive scalar field with general curvature coupling parameter satisfying Robin boundary conditions on two codimension one parallel branes embedded in ($D+1$)-dimensional background spacetime ${\mathrm{AdS}}_{D_1+1}\times \Sigma$ with a warped internal space $\Sigma$. The vacuum energy-momentum tensor is presented as a sum of boundary-free, single brane-induced, and interference parts. The latter is finite everywhere including the points on the branes and is exponentially small for large interbrane distances. Unlike to the purely anti–de Sitter (AdS) bulk, the part induced by a single brane, in addition to the distance from the brane, depends also on the position of the brane in the bulk. The asymptotic behavior of this part is investigated for the points near the brane and for the position of the brane close to the AdS horizon and AdS boundary. The contribution of Kaluza-Klein modes along $\Sigma$ is discussed in various limiting cases. The vacuum forces acting on the branes are presented as a sum of the self-action and interaction terms. The first one contains well-known surface divergences and needs a further renormalization. The interaction forces between the branes are finite for all nonzero interbrane distances and are investigated as functions of the brane positions and the length scale of the internal space. We show that there is a region in the space of parameters in which these forces are repulsive for small distances and attractive for large distances. As an example, the case $\Sigma =S^{D_2}$ is considered. An application to the higher dimensional generalization of the Randall-Sundrum brane model with arbitrary mass terms on the branes is discussed. Taking the limit with infinite curvature radius for the AdS bulk, from the general formulas we derive the results for two parallel Robin plates on background of $R^{(D_1,1)}\times \Sigma$ spacetime.

In this paper, we find some new exact solutions to the Einstein-Gauss-Bonnet equations. First, we prove a theorem which allows us to find a large family of solutions to the Einstein-Gauss-Bonnet gravity in $n$-dimensions. This family of solutions represents dynamic black holes and contains, as particular cases, not only the recently found Vaidya-Einstein-Gauss-Bonnet black hole, but also other physical solutions that we think are new, such as the Gauss-Bonnet versions of the Bonnor-Vaidya (de Sitter/anti-de Sitter) solution, a global monopole, and the Husain black holes. We also present a more general version of this theorem in which less restrictive conditions on the energy-momentum tensor are imposed. As an application of this theorem, we present the exact solution describing a black hole radiating a charged null fluid in a Born-Infeld nonlinear electrodynamics.