The Borel summation technique of infrared renormalons is applied to the lattice determination of heavy-quark mass. With Borel summation a physical heavy-quark pole mass and binding energy of a heavy-light meson can be defined in a rigorous and calculable manner. A notable feature of the Borel summation, compared to the usual perturbative cancellation of IR renormalons, is an automatic scale isolation. The two approaches of handling renormalon divergence are compared in the B-meson as well as in an (imaginary) heavy-light meson with a mass much larger than the inverse of the lattice spacing.

We present a next-to-leading-order calculation of the production of a $Z$ boson with two jets, one or more of which contains a heavy quark ($Q=c,b$). We show that the cross section with only one heavy-quark jet is larger than that with two heavy-quark jets at both the Fermilab Tevatron and the CERN LHC. These processes are the dominant irreducible backgrounds to a Higgs boson produced in association with a $Z$ boson, followed by $h\to b\overline{b}$. Our calculation makes use of a heavy-quark distribution function, which resums collinear logarithms and makes the next-to-leading-order calculation tractable.

I discuss scenarios for scalar glueballs using arguments based on sum rules, spectral decomposition, the $\frac{1}{N_c}$ approximation, the scales of the strong interaction and the topology of the flux tubes. I analyze the phenomenological support of those scenarios and their observational implications. My investigations hint a rich low lying glueball spectrum.

The QED contribution to the anomalous magnetic moments of electron and muon are known very precisely up to the order ${\alpha }^4$. However, the knowledge of the ${\alpha }^5$ term will also be required when the precision of measurement improves further. This paper reports the first systematic attempt to evaluate the ${\alpha }^5$ term. Feynman diagrams contributing to this term can be classified into six gauge-invariant sets which can be subdivided further into 32 gauge-invariant subsets. Thus far we have numerically evaluated all integrals of 17 gauge-invariant subsets which contain light-by-light-scattering subdiagrams and/or vacuum-polarization subdiagrams. They cover most of leading terms of muon $g-2$ and lead to a preliminary result 663 (20) $(\alpha /\pi {)}^5$, which is 8.5 times more precise than the old estimate.

Based on $5.8\times {10}^{7}J/\psi$ events collected with BESII at the Beijing Electron-Positron Collider (BEPC), the decay branching fractions of $J/\psi \to \omega {\pi }^0$, $\omega \eta$, and $\omega {\eta }^{\prime }$ are measured using different $\eta$ and ${\eta }^{\prime }$ decay modes. The results are higher than previous measurements. The $\omega {\pi }^0$ electromagnetic form factor is also obtained.

We present a study of the decay $B^{-}\to D_{(CP)}^0{K}^{-}$ and its charge conjugate, where $D_{(CP)}^0$ is reconstructed in $CP$-even, $CP$-odd, and non-$CP$ flavor eigenstates, based on a sample of $232\times {10}^6$ $\mathit{{\rm Y}}(4S)\to B\overline{B}$ decays collected with the BABAR detector at the PEP-II $e^{+}{e}^{-}$ storage ring. We measure the partial-rate charge asymmetries $A_{CP\pm }$ and the ratios $R_{CP\pm }$ of the $B\to D^{0}K$ decay branching fractions as measured in $CP\pm$ and non-$CP$ $D^0$ decays: $A_{CP+}=0.35\pm 0.13(\mathrm{\text{stat}})\pm 0.04(\mathrm{\text{syst}})$, $A_{CP-}=-0.06\pm 0.13(\mathrm{\text{stat}})\pm 0.04(\mathrm{\text{syst}})$, $R_{CP+}=0.90\pm 0.12(\mathrm{\text{stat}})\pm 0.04(\mathrm{\text{syst}})$, and $R_{CP-}=0.86\pm 0.10(\mathrm{\text{stat}})\pm 0.05(\mathrm{\text{syst}})$.

In this work the following lepton flavor violating $\tau$ and $\mu$ decays are studied: ${\tau }^{-}\to {\mu }^{-}{\mu }^{-}{\mu }^{+}$, ${\tau }^{-}\to e^{-}{e}^{-}{e}^{+}$, ${\mu }^{-}\to e^{-}{e}^{-}{e}^{+}$, ${\tau }^{-}\to {\mu }^{-}\gamma$, ${\tau }^{-}\to e^{-}\gamma$, and ${\mu }^{-}\to e^{-}\gamma$. We work in a supersymmetric scenario consisting of the minimal supersymmetric standard model particle content, extended by the addition of three heavy right-handed Majorana neutrinos and their supersymmetric partners, and where the generation of neutrino masses is done via the seesaw mechanism. Within this context, a significant lepton flavor mixing is generated in the slepton sector due to the Yukawa neutrino couplings, which is transmitted from the high to the low energies via the renormalization group equations. This slepton mixing then generates via loops of supersymmetric particles significant contributions to the rates of $l_j\to 3l_i$ and the correlated $l_j\to l_i\gamma$ decays. We analyze here in full detail these rates in terms of the relevant input parameters, which are the usual minimal supergravity parameters and the seesaw parameters. For the $l_j\to 3l_i$ decays, a full one-loop analytical computation of all the contributing supersymmetric loops is presented. This completes and corrects previous computations in the literature. In the numerical analysis compatibility with the most recent experimental upper bounds on all these $\tau$ and $\mu$ decays, with the neutrino data, and with the present lower bounds on the supersymmetric particle masses are required. Two typical scenarios with degenerate and hierarchical heavy neutrinos are considered. We will show here that the minimal supergravity and seesaw parameters do get important restrictions from these $\tau$ and $\mu$ decays in the hierarchical neutrino case.

This paper concerns instanton contributions to two-point correlation functions of Berenstein-Maldacena-Nastase (BMN) operators in $\mathcal{N}=4$ supersymmetric Yang-Mills theory that vanish in planar perturbation theory. Two-point functions of operators with even numbers of fermionic impurities (dual to $\mathrm{R}\otimes \mathrm{R}$ string states) and with purely scalar impurities (dual to $\mathrm{NS}\otimes \mathrm{NS}$ string states) are considered. This includes mixed $\mathrm{R}\otimes \mathrm{R}–\mathrm{NS}\otimes \mathrm{NS}$ two-point functions. The gauge theory correlation functions are shown to respect BMN scaling and their behavior is found to be in good agreement with the corresponding $D$-instanton contributions to two-point amplitudes in the maximally supersymmetric IIB plane wave string theory. The string theory calculation also shows a simple dependence of the mass matrix elements on the mode numbers of states with an arbitrary number of impurities, which is difficult to extract from the gauge theory. For completeness, a discussion is also given of the perturbative mixing of two impurity states in the $\mathrm{R}\otimes \mathrm{R}$ and $\mathrm{NS}\otimes \mathrm{NS}$ sectors at the first nonplanar level.

We discuss a slow-moving limit of a rigid circular equal-spin solution on $R\times S^3$. We suggest that the solution with the winding number equal to the total spin approximates the quantum string state dual to the maximal-dimension “antiferromagnetic” state of the $SU(2)$ spin chain on the gauge-theory side. An expansion of the string action near this solution leads to a weakly-coupled system of a sine-Gordon model and a free field. We show that a similar effective Hamiltonian appears in a certain continuum limit from the half-filled Hubbard model that was recently suggested to describe the all-order dilatation operator of the dual gauge theory in the $SU(2)$ sector. We also discuss some other slow-string solutions with one spin component in $\mathrm{Ad}{\mathrm{S}}_5$ and one in $S^5$.

We present a new method for computing complete one-loop amplitudes, including their rational parts, in nonsupersymmetric gauge theory. This method merges the unitarity method with on-shell recursion relations. It systematizes a unitarity-factorization bootstrap approach previously applied by the authors to the one-loop amplitudes required for next-to-leading order QCD corrections to the processes $e^{+}{e}^{-}\to Z,{\gamma }^{*}\to 4$ jets and $pp\to W+2$ jets. We illustrate the method by reproducing the one-loop color-ordered five-gluon helicity amplitudes in QCD that interfere with the tree amplitude, namely $A_{5;1}(1^{-},2^{-},3^{+},4^{+},5^{+})$ and $A_{5;1}(1^{-},2^{+},3^{-},4^{+},5^{+})$. Then we describe the construction of the six- and seven-gluon amplitudes with two adjacent negative-helicity gluons, $A_{6;1}(1^{-},2^{-},3^{+},4^{+},5^{+},6^{+})$ and $A_{7;1}(1^{-},2^{-},3^{+},4^{+},5^{+},6^{+},7^{+})$, which uses the previously-computed logarithmic parts of the amplitudes as input. We present a compact expression for the six-gluon amplitude. No loop integrals are required to obtain the rational parts.

We study the possibility of having a static, asymptotically AdS black hole localized on a braneworld with matter fields, within the framework of the Randall and Sundrum scenario. We attempt to look for such a brane black hole configuration by slicing a given bulk spacetime and taking ${\mathbb{Z}}_2$ symmetry about the slices. We find that such configurations are possible, and as an explicit example, we provide a family of asymptotically AdS brane black hole solutions for which both the bulk and brane metrics are regular on and outside the black hole horizon and brane matter fields are realistic in the sense that the dominant energy condition is satisfied. We also find that our braneworld models exhibit signature change inside the black hole horizon.

We consider a simple toy model of a regular bouncing universe. The bounce is caused by an extra timelike dimension, which leads to a sign flip of the ${\rho }^2$ term in the effective four dimensional Randall Sundrum-like description. We find a wide class of possible bounces: big bang avoiding ones for regular matter content, and big rip avoiding ones for phantom matter. Focusing on radiation as the matter content, we discuss the evolution of scalar, vector and tensor perturbations. We compute a spectral index of $n_s=-1$ for scalar perturbations and a deep blue index for tensor perturbations after invoking vacuum initial conditions, ruling out such a model as a realistic one. We also find that the spectrum (evaluated at Hubble crossing) is sensitive to the bounce. We conclude that it is challenging, but not impossible, for cyclic/ekpyrotic models to succeed, if one can find a regularized version.

A gravity-driven mechanism (“objective reduction”) proposed to explain quantum state reduction is analyzed in light of the possible existence of large extra dimensions in the Arkani-Hamed, Dvali, Dimopoulos scenario. By calculating order-of-magnitude estimates for nucleon superpositions, it is shown that if the mechanism at question is correct, constraints may be placed on the number and size of extra dimensions. Hence, measurement of superposition collapse times (e.g. through diffraction or reflection experiments) could represent a new probe of extra dimensions. The influence of a time-dependent gravitational constant on the gravity-driven collapse scheme with and without the presence of extra dimensions also is discussed.

The dwarf spheroidal galaxy Draco has long been considered likely to be one of the brightest point sources of gamma rays generated through dark matter annihilations. Recent studies of this object have found that it remains largely intact from tidal striping, and may be more massive than previously thought. In this article, we revisit Draco as a source of dark matter annihilation radiation, with these new observational constraints in mind. We discuss the prospects for the experiments MAGIC and GLAST to detect dark matter in Draco, as well as constraints from the observations of EGRET. We also discuss the possibility that the CACTUS experiment has already detected gamma rays from Draco. We find that it is difficult to generate the flux reported by CACTUS without resorting to nonthermally produced WIMPs and/or a density spike in Draco’s dark matter distribution due to the presence of an intermediate mass black hole. We also find that for most annihilation modes, a positive detection of Draco by CACTUS would be inconsistent with the lack of events seen by EGRET.

The gravitational collapse of a spherically symmetric star, made of a dust fluid, ${\rho }_{\mathrm{DM}}$, in a background of dark energy, $p=w\rho$ ($w<-1/3$) is studied. It is found that when only dark energy is present, black holes are never formed. When both of them are present, black holes can be formed, due to the condensation of the dust fluid. Initially the dust fluid may not play an important role, but, as time increases, it will dominate the collapse and finally lead to formation of black holes. This result remains true even when the interaction between the dust fluid and dark energy does not vanish. When $w<-1$ (phantoms), some models also can be interpreted as representing the death of a white hole that ejects both dust and phantoms. The ejected matter recollapses to form a black hole.

We compute the complete one-loop corrections to the simplest class of QCD gluon amplitudes, those with two color-adjacent opposite-helicity external particles. We present results for an arbitrary number of external legs. This is the first all-$n$ computation of amplitudes that enter into collider observables at next-to-leading order. The computation uses the recently-developed on-shell recursion relations for the rational parts, along with older unitarity-based results for the cut-containing terms.

Quasi two-body decays $B^0(t)\to a_1^{\pm }(1260){\pi }^{\mp }$ identified by four charged pions determine a phase ${\alpha }_{\mathrm{eff}}$, which is equal to the weak phase $\alpha$ in the limit of vanishing penguin amplitudes. Applying flavor SU(3) to these decays and to $B\to a_{1}K$ and $B\to K_1\pi$, with $K_1$ an admixture of $K_1(1270)$ and $K_1(1400)$, we derive expressions providing bounds on $\alpha -{\alpha }_{\mathrm{eff}}$. Higher precision in $\alpha$ may be achieved by an overall fit to a complete set of SU(3) related measurements. A method is sketched applying isospin symmetry to time-dependent invariant mass distributions in $B\to {\pi }^{+}{\pi }^{-}{\pi }^0{\pi }^0$.

Methods are proposed for measuring the ratio $R^{+/0}=\Gamma ({\rm Y}(4S)\to B^{+}{B}^{-})/\Gamma ({\rm Y}(4S)\to B^0{\overline{B}}^0)$ without assuming isospin invariance in exclusive hadronic decays such as $B\to J/\psi K$. The validity of isospin invariance in various $B$ decays is discussed. Isospin violations are expected to be especially small in inclusive semileptonic decays, so that $\Gamma (B^{+}\to X_c^0{\ell }^{+}{\nu }_{\ell })=\Gamma (B^0\to X_c^{-}{\ell }^{+}{\nu }_{\ell })$ is expected to hold at the subpercent level. Suggestions are made for utilizing this relation. The accuracy of a “double-tag” method for obtaining $R^{+/0}$, such as that used for measuring the $D^{+}{D}^{-}/D^0{\overline{D}}^0$ ratio at the ${\psi }^{\prime \prime }\equiv \psi (3770)$, is also estimated.

At the LHC and at an ILC, serious studies of new physics benefit from a proper simulation of signals and backgrounds. Using supersymmetric sbottom pair production as an example, we show how multiparticle final states are necessary to properly describe off-shell effects induced by QCD, photon radiation, or by intermediate on-shell states. To ensure the correctness of our findings we compare in detail the implementation of the supersymmetric Lagrangian in madgraph, sherpa and whizard. As a future reference we give the numerical results for several hundred cross sections for the production of supersymmetric particles, checked with all three codes.

The lightest neutralino is a viable dark matter (DM) candidate. In this paper we study indirect detection of the wino-like neutralino DM using positrons and antiprotons from the annihilation in the galactic halo. When the mass is around 2 TeV, which is favored from the thermal relic abundance, the nonperturbation effect significantly enhances the annihilation cross sections into positrons and antiprotons. We find that the positron and antiproton fluxes with energies larger than 100 GeV may become larger than the expected backgrounds. Since the positron flux is less sensitive to the astrophysical parameters, the detection may be promising in the upcoming experiments such as PAMELA and AMS-02. We also find the wino-like neutralino DM with mass around 2 TeV is compatible with the HEAT anomaly.