We study the production of Higgs boson ($\varphi$) via the $e^{-}{e}^{+}\to e^{-}{e}^{+}\varphi$ process at a future International Linear Collider (ILC) with $\sqrt{S}=1\mathrm{TeV}$. At this energy the $ZZ$-fusion rate, as predicted by the standard model, dominates over the associated $ZH$ production rate. Here, we consider a class of theory models based on the effective $\varphi VV$ (with $V=Z$, $\gamma$) couplings generated by dimension-6 operators. We also show how to use the kinematical distributions of the final state leptons to discriminate the $CP$-even and $CP$-odd Higgs bosons produced at the ILC, when the $\varphi \gamma \gamma$ coupling dominates the Higgs boson production rate.

We consider a class of little Higgs theories with $T$-parity where all new particles responsible for canceling the standard model contributions to the one-loop quadratic divergences in the Higgs potential are odd under $T$-parity, including the heavy top partner which was previously taken to be $T$-even. The new construction significantly simplifies the spectrum in the top sector and completely changes the phenomenology of the top partner. At hadron colliders the signals of this class of $T$-invariant models appear to be even more similar to supersymmetry. We initiate a study on the collider phenomenology and discuss the challenge of distinguishing this class of models from supersymmetry at the Large Hadron Collider.

We construct the full axial current of the constituent quarks by a summation of the infinite number of diagrams describing constituent quark soft interactions. By requiring that the conservation of this current is violated only by terms of order $O(M_{\pi }^2)$, where $M_{\pi }$ is the mass of the lowest pseudoscalar $\overline{Q}Q$ bound state, we derive important constraints on (i) the axial coupling $g_A$ of the constituent quark and (ii) the $\overline{Q}Q$ potential at large distances. We define the chiral point of the constituent quark model as those values of the parameters, such as the masses of the constituent quarks and the couplings in the $\overline{Q}Q$ potential, for which $M_{\pi }$ vanishes. At the chiral point the main signatures of the spontaneously broken chiral symmetry are shown to be present, namely: the axial current of the constituent quarks is conserved, the leptonic decay constants of the excited pseudoscalar bound states vanish, and the pion decay constant has a nonzero value.

We describe searches for $B$ meson decays to the charmless vector-vector final states $\omega K^{*}$, $\omega \rho$, $\omega \omega$, and $\omega \varphi$ with $233\times {10}^6$ $B\overline{B}$ pairs produced in $e^{+}{e}^{-}$ $B\overline{B}$ annihilation at $\sqrt{s}=10.58\mathrm{GeV}$. We also search for the vector-scalar $B$ decay to $\omega f_0$. We measure the following branching fractions in units of ${10}^{-6}$: $\mathcal{B}(B^0\to \omega K^{*0})=2.4\pm 1.1\pm 0.7(<4.2)$, $\mathcal{B}(B^{+}\to \omega K^{*+})={0.6}_{-1.2-0.9}^{+1.4+1.1}(<3.4)$, $\mathcal{B}(B^0\to \omega {\rho }^0)=-0.6\pm {0.7}_{-0.3}^{+0.8}(<1.5)$, $\mathcal{B}(B^{+}\to \omega {\rho }^{+})=10.6\pm {2.1}_{-1.0}^{+1.6}$, $\mathcal{B}(B^0\to \omega \omega )={1.8}_{-0.9}^{+1.3}\pm 0.4(<4.0)$, $\mathcal{B}(B^0\to \omega \varphi )=0.1\pm 0.5\pm 0.1(<1.2)$, and $\mathcal{B}(B^0\to \omega f_0)=0.9\pm {0.4}_{-0.1}^{+0.2}(<1.5)$. In each case the first error quoted is statistical, the second systematic, and the upper limits are defined at the 90% confidence level. For $B^{+}\to \omega {\rho }^{+}$ decays we also measure the longitudinal spin component $f_L=0.82\pm 0.11\pm 0.02$ and the charge asymmetry ${\mathcal{A}}_{CP}=0.04\pm 0.18\pm 0.02$.

In this paper the spectrum of quark-antiquark systems, including light mesons and tachyons, is studied in the true vacuum and in the chiral invariant vacuum. The mass gap equation for the vacua and the Salpeter-RPA equation for the mesons are solved for a simple chiral invariant and confining quark model. At $T=0$ and in the true vacuum, the scalar and pseudoscalar, or the vector and axial vector are not degenerate, and in the chiral limit, the pseudoscalar groundstates are Goldstone bosons. At $T=0$ the chiral invariant vacuum is an unstable vacuum, decaying through an infinite number of scalar and pseudoscalar tachyons. Nevertheless the axialvector and vector remain mesons, with real masses. To illustrate the chiral restoration, an arbitrary path between the two vacua is also studied. Different families of light-light and heavy-light mesons, sensitive to chiral restoration, are also studied. At higher temperatures the potential must be suppressed, and the chiral symmetry can be restored without tachyons, but then all mesons have small real masses. Implications for heavy-ion collisions, in particular, for the recent vector meson spectra measured by the NA60 collaboration, are discussed.

We discuss conservation laws for gravity theories invariant under general coordinate and local Lorentz transformations. We demonstrate the possibility to formulate these conservation laws in many covariant and noncovariant(ly looking) ways. An interesting mathematical fact underlies such a diversity: there is a certain ambiguity in a definition of the (Lorentz-) covariant generalization of the usual Lie derivative. Using this freedom, we develop a general approach to the construction of invariant conserved currents generated by an arbitrary vector field on the spacetime. This is done in any dimension, for any Lagrangian of the gravitational field and of a (minimally or nonminimally) coupled matter field. A development of the “regularization via relocalization” scheme is used to obtain finite conserved quantities for asymptotically nonflat solutions. We illustrate how our formalism works by some explicit examples.

Lovelock gravity is a fascinating extension of general relativity, whose action consists of dimensionally extended Euler densities. Compared to other higher order derivative gravity theories, Lovelock gravity is attractive since it has a lot of remarkable features such as the fact that there are no more than second order derivatives with respect to the metric in its equations of motion, and that the theory is free of ghosts. Recently, in the study of black strings and black branes in Lovelock gravity, a special class of Lovelock gravity is considered, which is named pure Lovelock gravity, where only one Euler density term exists. In this paper we study black hole solutions in the special class of Lovelock gravity and associated thermodynamic properties. Some interesting features are found, which are quite different from the corresponding ones in general relativity.

We clarify the relationship between $SU(2{)}_L\times SU(2{)}_R$ restoration in the hadron spectrum, parity doubling, and pion-hadron couplings.

We compute the condensate in QCD with a single quark flavor using numerical simulations with the overlap formulation of lattice fermions. The condensate is extracted by fitting the distribution of low-lying eigenvalues of the Dirac operator in sectors of fixed topological charge to the predictions of Random Matrix Theory. Our results are in excellent agreement with estimates from the orientifold large-$N_c$ expansion.

Motivated by recent BABAR measurements of the ${\gamma }^{*}\to \gamma \eta$ and ${\gamma }^{*}\to \gamma {\eta }^{\prime }$ transition form factors, we estimate two-photon exchange contributions to the corresponding cross sections. By using a phenomenological model, based on the vector meson dominance, it is argued that the expected contributions are small enough not to effect the BABAR results. As a by product we predict $\mathrm{Br}({\eta }^{\prime }\to {\mu }^{+}{\mu }^{-})=(1.4\pm 0.2)\times {10}^{-7}$. Our results might be useful also in high precision calculations of radiative corrections to the Dalitz decays of pseudoscalar mesons.

The three-gluon glueball states are studied with the generalization of a semirelativistic potential model giving good results for two-gluon glueballs. The Hamiltonian depends only on 3 parameters fixed on two-gluon glueball spectra: the strong coupling constant, the string tension, and a gluon size which removes singularities in the potential. The Casimir scaling determines the structure of the confinement. Low-lying $J^{PC}$ states are computed and compared with recent lattice calculations. A good agreement is found for $1^{--}$ and $3^{--}$ states, but our model predicts a $2^{--}$ state much higher in energy than the lattice result. The $0^{-+}$ mass is also computed.

We study a QCD sum rule analysis for an exotic tetraquark $ud\overline{s}\overline{s}$ of $J^P=0^{+}$ and $I=1$. We construct $qq\overline{q}\overline{q}$ currents in a local product form and find that there are five independent currents for this channel. Because of the high dimensional nature of the current, it is not easy to form a good sum rule when using a single current. This means that we do not find any sum rule window to extract reliable results, due to the insufficient convergence of the operator product expansion and to the exceptional important role of QCD continuum. Then we examine sum rules by using currents of linear combinations of two currents among the independent ones. We find two reasonable cases that predict a mass of the tetraquark around 1.5 GeV.

An analytical solution to a parametric resonance effect for antineutrinos in a $3+1$ flavor ($\mathrm{\text{active}}+\mathrm{\text{sterile}}$) scheme using multiple nonadiabatic density shifts is presented. We derive the conditions for a full flavor conversion for antineutrino oscillations ${\overline{\nu }}_{\alpha }\to {\overline{\nu }}_s$ $(\alpha =e,\mu ,\tau )$ under the assumption that LSND best-fits for the mixing parameters are valid in a short-baseline accelerator experiment. We show that the parametric resonance effect can be exploited to increase the effective antineutrino oscillation length by a factor of 10–40, thus sustaining a high oscillation probability for a much longer period of time than in the vacuum scenario. We propose a realistic experimental setup that could probe for this effect which leaves a signature in terms of a specific oscillation probability profile. Moreover, since the parametric resonance effect is valid in any 2 or $1+1$ flavor approximation, our results could be suggestive for future short-baseline accelerator neutrino detection experiments.

We present measurements of branching fractions of $B^0$ decays to multibody final states containing protons, based on $232\times {10}^6$ ${\rm Y}(4S)\to B\overline{B}$ decays collected with the BABAR detector at the SLAC PEP-II asymmetric-energy $B$ factory. We measure the branching fractions $\mathcal{B}(B^0\to {\overline{D}}^{0}p\overline{p})=(1.13\pm 0.06\pm 0.08)\times {10}^{-4}$, $\mathcal{B}(B^0\to {\overline{D}}^{*0}p\overline{p})=(1.01\pm 0.10\pm 0.09)\times {10}^{-4}$, $\mathcal{B}(B^0\to D^{-}p\overline{p}{\pi }^{+})=(3.38\pm 0.14\pm 0.29)\times {10}^{-4}$, and $\mathcal{B}(B^0\to D^{*-}p\overline{p}{\pi }^{+})=(4.81\pm 0.22\pm 0.44)\times {10}^{-4}$ where the first error is statistical and the second systematic. We present a search for the charmed pentaquark state, ${\Theta }_c(3100)$ observed by H1 and put limits on the branching fraction $\mathcal{B}(B^0\to {\Theta }_c\overline{p}{\pi }^{+})\times \mathcal{B}({\Theta }_c\to D^{*-}p)<14\times {10}^{-6}$ and $\mathcal{B}(B^0\to {\Theta }_c\overline{p}{\pi }^{+})\times \mathcal{B}({\Theta }_c\to D^{-}p)<9\times {10}^{-6}$. Upon investigation of the decay structure of the above four $B^0$ decay modes, we see an enhancement at low $p\overline{p}$ mass and deviations from phase-space in the $\overline{D}\overline{p}$ and $\overline{D}p$ invariant mass spectra.

We investigate giant magnons from classical rotating strings in two different backgrounds. First we generalize the solution of Hofman and Maldacena and investigate new magnon excitations of a spin chain which are dual to a string on $R\times S^5$ with two nonvanishing angular momenta. Allowing string dynamics along the third angle in the five sphere, we find a dispersion relation that reproduces the Hofman and Maldacena one and the one found by Dorey for the two spin case. In the second part of the paper we generalize the two “spin” giant magnon to the case of $\beta$-deformed ${\mathrm{AdS}}_5\times S^5$ background. We find agreement between the dispersion relation of the rotating string and the proposed dispersion relation of the magnon bound state on the spin chain.

We show that all three conditions for the cosmological relevance of heterotic cosmic strings, the right tension, stability and a production mechanism at the end of inflation, can be met in the strongly coupled M-theory regime. Whereas cosmic strings generated from weakly coupled heterotic strings have the well-known problems posed by Witten in 1985, we show that strings arising from M5-branes wrapped around 4-cycles (divisors) of a Calabi-Yau in heterotic M-theory compactifications solve these problems in an elegant fashion.

Dark matter in the form of particles from a hidden mirror sector has recently been proposed as an explanation for the DAMA annual modulation signal. Here one assumes that there exists a small mixing between photons and mirror photons. We show that dark matter with this property can also be detected in electromagnetic field penetration experiments. Such experiments can be used to measure the speed and direction of the dark matter halo wind, the local density, the temperature, and the strength of the photon-mirror photon mixing interaction. An additional result would be a significant improvement of the upper limit on the photon mass.

We investigate the impact of quantum fluctuations on a light rolling quintessence field from three different sources, namely, from a coupling to the standard model and dark matter, from its self-couplings, and from its coupling to gravity. We derive bounds for time-varying masses from the change of vacuum energy, finding $\Delta m_e/m_e\ll {10}^{-11}$ for the electron and $\Delta m_p/m_p\ll {10}^{-15}$ for the proton since redshift $z\sim 2$, whereas the neutrino masses could change of order one. Mass-varying dark matter is also constrained. Next, the self-interactions are investigated. For inverse power law potentials, the effective potential does not become infinitely large at small field values, but saturates at a finite maximal value. We discuss implications for cosmology. Finally, we show that one-loop corrections induce nonminimal gravitational couplings involving arbitrarily high powers of the curvature scalar $R$, indicating that quintessence entails modified gravity effects.

The recently developed on-shell bootstrap for computing one-loop amplitudes in nonsupersymmetric theories such as QCD combines the unitarity method with loop-level on-shell recursion. For generic helicity configurations, the recursion relations may involve undetermined contributions from nonstandard complex singularities or from large values of the shift parameter. Here we develop a strategy for sidestepping difficulties through the use of pairs of recursion relations. To illustrate the strategy, we present sets of recursion relations needed for obtaining $n$-gluon amplitudes in QCD. We give a recursive solution for the one-loop $n$-gluon QCD amplitudes with three or four color-adjacent gluons of negative helicity and the remaining ones of positive helicity. We provide an explicit analytic formula for the QCD amplitude $A_{6;1}(1^{-},2^{-},3^{-},4^{+},5^{+},6^{+})$, as well as numerical results for $A_{7;1}(1^{-},2^{-},3^{-},4^{+},5^{+},6^{+},7^{+})$, $A_{8;1}(1^{-},2^{-},3^{-},4^{+},5^{+},6^{+},7^{+},8^{+})$, and $A_{8;1}(1^{-},2^{-},3^{-},4^{-},5^{+},6^{+},7^{+},8^{+})$. We expect the on-shell bootstrap approach to have widespread applications to phenomenological studies at colliders.