Polarization as a Probe to the Production Mechanisms of Charmonium in πN\pi N Collisions

Measurements of the polarization of \jp produced in pion-nucleus collisions are in disagreement with leading twist QCD prediction where \jp is observed to have negligible polarization whereas theory predicts substantial polarization. We argue that this discrepancy cannot be due to poorly known structure functions nor the relative production rates of \jp and $\chi_J$. The disagreement between theory and experiment suggests important higher twist corrections, as has earlier been surmised from the anomalous non-factorized nuclear $A$-dependence of the \jp cross section.Comment: 8 page

Photon-meson transition form factors of light pseudoscalar mesons

The photon-meson transition form factors of light pseudoscalar mesons $\pi ^{0}$, $\eta$, and $\eta ^{\prime}$ are systematically calculated in a light-cone framework, which is applicable as a light-cone quark model at low $Q^{2}$ and is also physically in accordance with the light-cone pQCD approach at large $Q^{2}$. The calculated results agree with the available experimental data at high energy scale. We also predict the low $Q^{2}$ behaviors of the photon-meson transition form factors of $\pi ^{0}$, $\eta$ and $\eta ^{\prime }$, which are measurable in $e+A({Nucleus})\to e+A+M$ process via Primakoff effect at JLab and DESY.Comment: 22 Latex pages, 7 figures, Version to appear in PR

Thermal Field Theory and Generalized Light Front Coordinates

The dependence of thermal field theory on the surface of quantization and on the velocity of the heat bath is investigated by working in general coordinates that are arbitrary linear combinations of the Minkowski coordinates. In the general coordinates the metric tensor $g_{\bar{\mu\nu}}$ is non-diagonal. The Kubo, Martin, Schwinger condition requires periodicity in thermal correlation functions when the temporal variable changes by an amount $-i\big/(T\sqrt{g_{\bar{00}}})$. Light front quantization fails since $g_{\bar{00}}=0$, however various related quantizations are possible.Comment: 10 page

Ridge Production in High-Multiplicity Hadronic Ultra-Peripheral Proton-Proton Collisions

An unexpected result at the RHIC and the LHC is the observation that high-multiplicity hadronic events in heavy-ion and proton-proton collisions are distributed as two "ridges", approximately flat in rapidity and opposite in azimuthal angle. We propose that the origin of these events is due to the inelastic collisions of aligned gluonic flux tubes that underly the color confinement of the quarks in each proton. We predict that high-multiplicity hadronic ridges will also be produced in the high energy photon-photon collisions accessible at the LHC in ultra-peripheral proton-proton collisions or at a high energy electron-positron collider. We also note the orientation of the flux tubes between the quark and antiquark of each high energy photon will be correlated with the plane of the scattered proton or lepton. Thus hadron production and ridge formation can be controlled in a novel way at the LHC by observing the azimuthal correlations of the scattering planes of the ultra-peripheral protons with the orientation of the produced ridges. Photon-photon collisions can thus illuminate the fundamental physics underlying the ridge effect and the physics of color confinement in QCD.Comment: Presented by SJB at Photon 2017: The International Conference on the Structure and the Interactions of the Photon and the International Workshop on Photon-Photon Collisions. CERN, May 22-26, 2017. References adde

Probing Intrinsic Charm with Semileptonic B Decays

We discuss semileptonic B decays of the form B -> J/Psi e nu X as possible probes of intrinsic charm. We calculate the leading order perturbative contribution to the process B- -> J/Psi e- nu_e X and find it to be unobservably small, with a branching ratio ~ 10^-10. We propose a modified spectator model to estimate the intrinsic charm contribution and find that it can be significantly larger, with a branching ratio for B -> (c cbar) e- nu_e X as large as 5 X 10^-7. We show that the process could be observed at these levels by CDF assuming a Run II integrated luminosity of 15 fb^-1, making this a useful reaction to probe the idea of intrinsic charm.Comment: 25 pages, LaTeX, 7 figures, uses epsf.sty. Version substantially revise

Gluon Virtuality and Heavy Sea Quark Contributions to the Spin-Dependent g_1 Structure Function

We analyze the quark mass dependence of photon gluon fusion in polarized deep inelastic scattering for both the intrinsic and extrinsic gluon distributions of the nucleon. We calculate the effective number of flavors for each of the heavy and light quark photon gluon fusion contributions to the first moment of the spin-dependent structure function $g_1(x)$.Comment: LaTex, 19 page

Tetramixing of vector and pseudoscalar mesons: A source of intrinsic quarks

The tetramixing of pseudoscalar mesons $\pi$-$\eta$-$\eta'$-$\eta_c$ and vector mesons $\omega$-$\rho$-$\phi$-$J/\psi$ are studied in the light-cone constituent quark model, and such mixing of four mesons provides a natural source for the intrinsic charm $c\bar{c}$ components of light mesons. By mixing with the light mesons, the charmonium states $J/\psi$ and $\eta_c$ could decay into light mesons more naturally, without introducing gluons or a virtual photon as intermediate states. Thus, the introduction of light quark components into $J/\psi$ is helpful to reproduce the new experimental data of $J/\psi$ decays. The mixing matrices and the $Q^2$ behaviors of the transition form factors are also calculated and compared with experimental data.Comment: 20 pages, 10 figures. Version for publication in PR

The interplay of soft and hard contributions in the electromagnetic pion form factor

We consider various relativistic models for the valence Fock-state wave function of the pion. These models are obtained from simple instant-form wave functions by applying a Melosh rotation to the spin part and by imposing physical constraints on the parameters. We discuss how the soft and the hard (perturbative) parts of the electromagnetic form factor are affected by the choice of the model and by the Melosh rotation.Comment: 3 pages, 2 eps-figures, uses espcrc2.st

The Resummed Photon Spectrum in Radiative Upsilon Decays

We present a theoretical prediction for the photon spectrum in radiative Upsilon decay including the effects of resumming the endpoint region, E_\gamma -> M_\Upsilon/2. Our approach is based on NRQCD and the soft collinear effective theory. We find that our results give much better agreement with data than the leading order NRQCD prediction.Comment: 4 pages, 6 figure

Experimental determination of the effective strong coupling constant

We present a first attempt to experimentally extract an effective strong coupling constant that we define to be a low Q2 extension of a previous definition by S. Brodsky et al. following an initial work of G. Grunberg. Using Jefferson Lab data and sum rules, we establish its Q2-behavior over the complete Q2-range. The result is compared to effective coupling constants inferred from different processes and to calculations based on Schwinger-Dyson equations, hadron spectroscopy or lattice QCD. Although the connection between the experimentally extracted effective coupling constants and the calculations is not established it is interesting to note that their behaviors are similar.Comment: Published in Physics Letters B 650 4 24