F-term Induced Flavor Mass Spectrum

New mechanism of generating flavor mass spectrum is proposed by using an O'Raifeartaigh-type supersymmetry breaking model. A desired bilinear form of fermion mass spectrum is naturally realized through F-components of gauge-singlet (nonet of SU(3) flavor symmetry) superfields, and the suitable charged-lepton mass relation is reproduced. The charged-slepton mass spectrum is non-degenerate in general, and can be even hierarchical (proportional to the charged-lepton masses in the specific case). Flavor changing neutral processes are suppressed since the charged-lepton and slepton (except for right-handed sneutrino) mass matrices are diagonalized simultaneously in the flavor space. The right-handed sneutrinos are light with the similar ratio to the lepton sector ($\tilde{m}_{\nu_R}$/$\tilde{m}_e \sim m_\nu$/$m_e$).Comment: 12 pages, no figur

On the gluon content of the eta and eta' mesons

A phenomenological analysis of radiative $V\to P\gamma$ and $P\to V\gamma$ decays is performed with the purpose of determining the gluonic content of the $\eta$ and $\eta^\prime$ wave functions. Our results show that within our model there is no evidence for a gluonium contribution in the $\eta$, $Z_\eta^2=0.00\pm 0.12$, or the $\eta^\prime$, $Z_{\eta^\prime}^2=0.04\pm 0.09$. In terms of a mixing angle description this corresponds to $\phi_P=(41.4\pm 1.3)^\circ$ and $|\phi_{\eta^\prime G}|=(12\pm 13)^\circ$. In addition, the $\eta$-$\eta^\prime$ mixing angle is found to be $\phi_P=(41.5\pm 1.2)^\circ$ if we don't allow for a gluonium component.Comment: 16 pages, 3 figures, JHEP style. First part of data fitting changed, conclusions not modifie

Searching for Composite Neutrinos in the Cosmic Microwave Background

We analyze signals in the Cosmic Microwave Background (CMB) in theories where the small Dirac neutrino masses arise as a consequence of the compositeness of right-handed neutrinos. In such theories, the right-handed neutrinos are massless ``baryons'' of a new strong gauge interaction. We find that the results crucially depend on whether or not the new strong sector undergoes chiral symmetry breaking. In the case with chiral symmetry breaking, we find that there are indeed signals in the CMB, but none of them is a direct consequence of neutrino compositeness. In contrast, if the underlying theory does not undergo chiral symmetry breaking, the large scattering cross-section among the composites gives rise to a sizable CMB signal over a wide region of the parameter space, and it can potentially probe whether the neutrino mass spectrum is hierarchical, inverse hierarchical, or degenerate. We also discuss collider constraints on the compositeness in the context of the CMB signals.Comment: 26 pages. References and clarifying comments added. Version appearing to JHE

Experimental Status of Exotic Mesons and the GlueX Experiment

One of the unanswered and most fundamental questions in physics regards the nature of the confinement mechanism of quarks and gluons in QCD. Exotic hybrid mesons manifest gluonic degrees of freedom and their spectroscopy will provide the data necessary to test assumptions in lattice QCD and the specific phenomenology leading to confinement. Within the past two decades a number of experiments have put forth tantalizing evidence for the existence of exotic hybrid mesons in the mass range below 2 GeV. This talk represents an overview of the available data and what has been learned. In looking toward the future, the GlueX experiment at Jefferson Laboratory represents a new initiative that will perform detailed spectroscopy of the light-quark meson spectrum. This experiment and its capabilities will be reviewed.Comment: 10 pages, 8 figures, 2nd Meeting of the APS Topical Group on Hadron Physics GHP06, Nashville, TN (10/22-10/24/06

Inclusive Semi-leptonic B Decays to order 1/m_b^4

We give a systematic way to compute higher orders in the 1/m_b expansion in inclusive semi-leptonic decays at tree level. We reproduce the known 1/m_b^3 terms and compute the 1/m_b^4 terms at tree level. The appearing non-perturbative parameters and the impact on the determination of V_{cb} are discussed.Comment: 23 pages, 3 figures, uses phystex.st

Determination of the magnetic susceptibility of the quark condensate using radiative heavy meson decays

We use a light-cone sum rule (LCSR) analysis of the branching ratios of radiative meson decays to contrain the value of the magnetic susceptibility of the quark condensate $\chi(\mu)$. For the first time, we use a complete set of three-particle distribution amplitudes that enables us to give a consistent prediction for the branching ratios. Furthermore we will make use of a very recent update of several non-perturbative parameters. Our final result for $\chi(\mu= 1 {\rm GeV})= 2.85 \pm 0.5 {\rm GeV}^{-2}$ (assuming asymptotic wave functions) agrees with the currently used value of $3.15 \pm 0.3 {\rm GeV}^{-2}$.Comment: 21 pages, 4 figures, references adde

Heavy Quarkonium States with the Holographic Potential

The quarkonium states in a quark-gluon plasma is examined with the heavy quark potential implied by the holographic principle. Both the vanila AdS-Schwarzschild metric and the one with an infrared cutoff are considered. The dissociation temperature is calculated by solving the Schr\"o dinger equation of the potential model. In the case of the AdS-Schwarzschild metric with a IR cutoff, the dissociation temperatures for $J/\psi$ and $\Upsilon$ with the U-ansatz of the potential are found to agree with the lattice results within a factor of two.Comment: 9 pages with 2 figues in Revte

Phase space constraints and statistical jet studies in heavy-ion collisions

The effect of the correlation induced by global momentum conservation on the two-particle distribution in nucleus-nucleus collisions is discussed, with a focus on the generic case of collisions with a non-vanishing impact parameter.Comment: 5 pages, invited talk at the RHIC & AGS Annual Users' Meeting, Brookhaven Nat. Lab. (USA) and at the EPS HEP 2007 Conference, Manchester (UK