We consider the expected level of primordial non-Gaussianities in models in which density perturbations are produced by spatial fluctuations in the decay rate of the inflaton. We consider non-Gaussianities resulting from the self-coupling of the field that controls the decay rate of the inflaton and non-Gaussianities resulting from the nonlinear relation between field and curvature perturbations. We show that in these scenarios non-Gaussianities are of the “local” form, i.e., well described by the ansatz $\mathcal{R}={\mathcal{R}}_g{+f}_{\mathrm{NL}}^{\mathcal{R}}\left({\mathcal{R}}_g^2-〈{\mathcal{R}}_g^2〉\right).\mathrm{}$ This is a consequence of the fact that they were created when modes were already outside the horizon. We show that $f_{\mathrm{NL}}^{\mathcal{R}}$ is naturally of the order of a few in these models, much larger than what is expected in the standard one field models of inflation ${(f}_{\mathrm{NL}}^{\mathcal{R}}\sim {10}^{-2})$ and possibly accessible to observations.

We present a mechanism to generate complex phases from real $4+1$ dimensional couplings in a model of weak interactions through dimensional reduction of a gauge theory. The orbifolding of a $4+1$ dimensional $\mathrm{Sp}\left(4\right)\mathrm{}\times U\left(1\right)\mathrm{}$ group is the minimal setup which provides both $\mathrm{CP}$ violation and an $\mathrm{SU}\left(2\right)\mathrm{}\times U\left(1\right)\mathrm{}$ structure. We show that grand unification requires at least $\mathrm{SO}\left(11\right).$

Isosinglet vectorlike quarks are predicted by some unified theories of electroweak and strong interactions. We study hadron collider signatures for the production and decay of isosinglet vectorlike quarks with charge $-1/3.$ Previous analyses of run I data from the Fermilab Tevatron are used to set lower limits of $100–200\mathrm{GeV}{/c}^2$ on the mass of such quarks, depending on assumptions about mixing with standard model quarks and the mass of the Higgs boson. For future Tevatron data ${(E}_{\mathrm{c}.\mathrm{m}.\mathrm{}}=1.96\mathrm{}\mathrm{TeV})$ the corresponding mass range is (100–270, 100–320) $\mathrm{GeV}{/c}^2$ for $(1,10){\mathrm{fb}}^{-1}.$ At the CERN Large Hadron Collider (LHC) ${(E}_{\mathrm{c}.\mathrm{m}.\mathrm{}}=14\mathrm{}\mathrm{TeV},$ $100{\mathrm{fb}}^{-1}),$ an analysis of flavor-changing neutral-current decay modes should probe an h quark mass range of $100–1100\mathrm{GeV}{/c}^2.$

In the minimal supersymmetric (SUSY) standard model, tau sleptons ${\tilde{\tau }}_{1,2}$ and neutralinos ${\tilde{\chi }}_{1,2}^0$ are expected to be among the lightest supersymmetric particles that can be produced copiously at future $e^{+}{e}^{-}$ linear colliders. We analyze $\tilde{\tau }$ pair and ${\tilde{\chi }}_1^0{\tilde{\chi }}_2^0$ production under the assumption $m_{{\tilde{\chi }}_1^0}<m_{{\tilde{\tau }}_1}<m_{{\tilde{\chi }}_2^0},$ allowing the relevant parameters of the SUSY Lagrangian to have complex phases. We show that the transverse and normal components of the polarization vector of the τ lepton produced in ${\tilde{\chi }}_2^0$ decays offer sensitive probes of these phases.

We study two CP sensitive triple-product asymmetries for neutralino production $e^{+}{e}^{-}\to {\tilde{\chi }}_i^0{\tilde{\chi }}_j^0$ and the subsequent leptonic two-body decay ${\tilde{\chi }}_i^0\to \mathcal{l}̃\mathcal{l},$ $\mathcal{l}̃$$\to {\tilde{\chi }}_1^0\mathcal{l},$ for $\mathcal{l}=e,\mu ,\tau .$ We calculate the asymmetries, cross sections and branching ratios in the minimal supersymmetric standard model with complex parameters $\mu$ and $M_1.$ We present numerical results for the asymmetries to be expected at a linear electron-positron collider in the 500 GeV range. The asymmetries can go up to 25%. We estimate the event rates which are necessary to observe the asymmetries. Polarized electron and positron beams can significantly enhance the asymmetries and cross sections. In addition, we show how the two decay leptons can be distinguished by making use of their energy distributions.

We investigate the quark mass dependence of the nucleon mass $M_N.$ An interpolation of this observable, between a selected set of fully dynamical two-flavor lattice QCD data and its physical value, is studied using relativistic baryon chiral perturbation theory up to order $p^4.$ In order to minimize uncertainties due to lattice discretization and finite volume effects our numerical analysis takes into account only simulations performed with lattice spacings $a<\mathrm{}0.15\mathrm{}\mathrm{fm}$ and $m_{\pi }L>\mathrm{}5.\mathrm{}$ We have also restricted ourselves to data with $m_{\pi }<600\mathrm{}\mathrm{MeV}$ and $m_{\mathrm{sea}}{=m}_{\mathrm{val}}.$ A good interpolation function is found already at the one-loop level and chiral order $p^3.$ We show that the next-to-leading one-loop corrections are small. From the $p^4$ numerical analysis we deduce the nucleon mass in the chiral limit $M_0\approx 0.88\mathrm{GeV}$ and the pion-nucleon sigma term ${\sigma }_N=(49\mathrm{}\pm 3)\mathrm{MeV}$ at the physical value of the pion mass.

The pseudoscalar “hairpin” vertex (i.e., quark-disconnected vertex) plays a key role in quenched chiral perturbation theory. Direct calculations using lattice simulations find that it has a significant dependence on the quark mass. I show that this mass dependence can be used to determine the quenched Gasser-Leutwyler constant $L_5.$ This complements the calculation of $L_5$ using the mass dependence of the axial decay constant of the pion. In an appendix, I discuss power counting for quenched chiral perturbation theory and describe the particular scheme used in this paper.

We discuss the degree of spin polarization of single top quarks produced via the Wg fusion process in ep collisions at DESY $\mathrm{TESLA}+\mathrm{HERA}p$ and CERN $\mathrm{CLIC}+\mathrm{LHC}$ energies $\sqrt{s}=1.6\mathrm{}$ and 5.3 TeV. A description of how to combine the cross sections of $e^{+}\overrightarrow{b}t\overline{\nu }$ and $e^{+}\overrightarrow{g}t\overline{b}\overline{\nu }$ processes is given. The $e^{+}$-beam direction is taken to be the favorite top quark spin decomposition axis in its rest frame and it is found to be comparable with the ones in pp collisions. It is argued that theoretical simplicity and experimental clearness are the advantage of ep collisions.

A general procedure is introduced allowing for the infinite decomposition of non-local vector operators off the light cone into operators of definite geometric twist. The method is applied to the operators $\overline{\psi }\mathrm{}\left(x\right)\mathrm{}{\gamma }_{\mu }\psi \left(-x\right)$ and $\overline{\psi }\mathrm{}\left(x\right)\mathrm{}{\sigma }_{\mu \nu }{x}^{\nu }\psi \left(-x\right)$ as well as to their matrix elements thereby determining all geometrical power (target mass) corrections being relevant for the related distribution amplitudes.

The B-meson distribution amplitude is calculated using QCD sum rules. In particular we obtain an estimate for the integral relevant to exclusive B decays ${\lambda }_B=460\mathrm{}\pm 110\mathrm{MeV}$ at the scale of 1 GeV. A simple QCD-motivated parametrization of the distribution amplitude is suggested.

It has recently been argued that soft-collinear effective theory for processes involving both soft and collinear partons contains a new soft-collinear mode, which can communicate between the soft and collinear sectors of the theory. The formalism incorporating the corresponding fields into the effective Lagrangian is extended to include external current and four-quark operators relevant to weak interactions. An explicit calculation of the anomalous dimensions of these operators reveals that soft-collinear modes are necessary to correctly extract the ultraviolet behavior of the effective theory.

The nonradiative scattering amplitudes for electron-positron annihilation into quark and lepton pairs in the TeV energy range are calculated in the double-logarithmic approximation. The expressions for the amplitudes are obtained using infrared evolution equations with different cutoffs for virtual photons and for W and Z bosons and compared with previous results obtained with a universal cutoff.

Direct CP violation can exist in untagged B-meson decays to self-conjugate, three-particle final states; it would be realized as a population asymmetry in the untagged decay rate across the mirror line of the Dalitz plot of the three-body decay. We explore the numerical size of this direct CP-violating effect in a variety of B-meson decays to three pseudoscalar mesons; we show that the resulting asymmetry is comparable to the partial rate asymmetry in the analogous tagged decays, making the search for direct CP violation in the untagged decay rate, for which greater statistics accrue, advantageous.

We calculate rates for hybrid meson production by electromagnetic and weak interactions in the flux-tube model. Applications include photoproduction and electroproduction at Jefferson Laboratory and DESY HERA, and the production of light strange and charmed hybrids in the weak decays of heavy flavors. Photoproduction of some light hybrids is predicted to be prominent in charge exchange reactions, $\gamma \overrightarrow{p}n\mathcal{H}$ and accessible in $\gamma \overrightarrow{p}p\mathcal{H}.$ Production of light or charmed hybrids in B and D decays may be feasible with high statistics. Photoproduction of the axial hybrid meson is predicted to be large courtesy of $\pi$ exchange, and its strange counterpart is predicted in $\overrightarrow{B}\psi K_H{(1\mathrm{}}^{+})$ with $\mathrm{BR}\sim {10}^{-4}.$ Production rates for exotic hybrid candidates $1^{-+}{;(0,2)\mathrm{}}^{+-}$ are given special attention. Selection rules that can help to distinguish between hybrid and conventional states with the same $J^{\mathrm{PC}}$ are noted.

Assuming that a nonstandard neutral Higgs boson with an enhanced Yukawa coupling to a bottom quark is observed at future hadron experiments, we propose a method for a better understanding of the Higgs sector. Our procedure is based on “counting” the number of events with heavy jets (where “heavy” stands for a c or b jet) versus b jets, in the final state of processes in which the Higgs boson is produced in association with a single high $p_{T}c$ or b jet. We show that an observed signal of the type proposed, at either the Fermilab Tevatron or CERN Large Hadron Collider (LHC), will rule out the popular two Higgs doublet model of type II as well as its supersymmeric version, the minimal supersymmetric standard model, and may provide new evidence in favor of some more exotic multi-Higgs-boson scenarios. As an example, we show that in a version of a two Higgs doublet model which naturally accounts for the large mass of the top quark, our signal can be easily detected at the LHC within that framework. We also find that such a signal may be observable at the upgraded Tevatron run III, if the neutral Higgs boson in this model has a mass around 100 GeV and $\tan \beta \gtrsim 50$ and if the efficiency for distinguishing a c jet from a light jet reaches the level of $\sim 50\%.$

Using a sample of $88.8\times {10}^6$ $B\overline{B}$ events collected with the BABAR detector at the PEP-II storage rings at the Stanford Linear Accelerator Center, we measure the branching fractions of seven color-suppressed B-meson decays: $\mathcal{B}(B^0\to D^0{\pi }^0)=[2.9\pm 0.2(\mathrm{stat})\pm 0.3(\mathrm{syst}\left)\right]\times {10}^{-4},$ $\mathcal{B}(B^0\to D^{*0}{\pi }^0)=[2.9\pm 0.4(\mathrm{stat})\pm 0.5(\mathrm{syst}\left)\right]\times {10}^{-4},$ $\mathcal{B}(B^0\to D^0\eta )=[2.5\pm 0.2(\mathrm{stat})\pm 0.3(\mathrm{syst}\left)\right]\times {10}^{-4},$ $\mathcal{B}(B^0\to D^{*0}\eta )=[2.6\pm 0.4(\mathrm{stat})\pm 0.4(\mathrm{syst}\left)\right]\times {10}^{-4},$ $\mathcal{B}(B^0\to D^0\omega )=[3.0\pm 0.3(\mathrm{stat})\pm 0.4(\mathrm{syst}\left)\right]\times {10}^{-4},$ $\mathcal{B}(B^0\to D^{*0}\omega )=[4.2\pm 0.7(\mathrm{stat})\pm 0.9(\mathrm{syst}\left)\right]\times {10}^{-4},$ and $\mathcal{B}(B^0\to D^0{\eta }^{\prime })=[1.7\pm 0.4(\mathrm{stat})\pm 0.2(\mathrm{syst}\left)\right]\times {10}^{-4}.$ We set the 90% confidence-level upper limit: $\mathcal{B}(B^0\to D^{*0}{\eta }^{\prime })<\mathrm{}2.6\mathrm{}\times {10}^{-4}.$ The channels $B^0\to D^{*0}\eta ,$ $D^{*0}\omega ,$ and $D^0{\eta }^{\prime }$ are seen with more than five-sigma statistical significance. All of these branching fractions are significantly larger than theoretical expectations based on the “naive” factorization model.

We present results on the production of high transverse momentum ${\pi }^0$ and η mesons in ${\pi }^{-}p$ and ${\pi }^{-}\mathrm{Be}$ interactions at $515\mathrm{GeV}/c.\mathrm{}$ The data span the kinematic ranges $1<\mathrm{}{p}_T<11\mathrm{}\mathrm{GeV}/c$ in transverse momentum and $-0.75<~y_{\mathrm{cm}}<~0.75$ in rapidity. The inclusive ${\pi }^0$ cross sections are compared with next-to-leading order QCD calculations and to expectations based on a phenomenological parton-$k_T$ model.

We have observed the rare decay $B^0\to {\rho }^{+}{\rho }^{-}$ in a sample of 89 million $B\overline{B}$ pairs recorded with the $\mathit{BABAR}$ detector. The number of observed events is ${88}_{-21}^{+23\mathrm{}}\pm 9,$ with a significance of 5.1 standard deviations with systematic uncertainties included. The branching fraction and the longitudinal polarization are measured to be $\mathcal{B}{(B}^0\to {\rho }^{+}{\rho }^{-}{)=(25\mathrm{}}_{-6-6}^{+7+5\mathrm{}})\times {10}^{-6}$ and ${\Gamma }_L/\Gamma {=0.98\mathrm{}}_{-0.08}^{+0.02\mathrm{}}\pm 0.03,$ respectively.

We investigate the properties of global monopoles with an event horizon. We find that there is an unstable circular orbit even if a particle does not have an angular momentum when the core mass is negative. We also obtain the asymptotic form of solutions when the event horizon is much larger than the core radius of the monopole, and discuss if they could be a model of galactic halos.

The generation of large-scale magnetic fields is studied in dilaton electromagnetism in inflationary cosmology, taking into account the dilaton’s evolution throughout inflation and reheating until it is stabilized with possible entropy production. It is shown that large-scale magnetic fields with an observationally interesting strength at the present time could be generated if the conformal invariance of the Maxwell theory is broken through the coupling between the dilaton and electromagnetic fields in such a way that the resultant quantum fluctuations in the magnetic field have a nearly scale-invariant spectrum. If this condition is met, the amplitude of the generated magnetic field could be sufficiently large even in the case that a huge amount of entropy is produced with the dilution factor $\sim {10}^{24}$ as the dilaton decays.