Probing Short Range Nucleon Correlations in High Energy Hard Quasielastic pd Reactions

We show that the strong dependence of the amplitude for $NN$ hard scattering on the collision energy can be used to magnify the effects of short range nucleon correlations in quasielastic $pd$ scattering. Under specific kinematical conditions the effect of initial and final state interactions can be accounted for by rescaling the cross section calculated within the plane wave impulse approximation. The feasibility to investigate the role of relativistic effects in the deuteron wave function is demonstrated by comparing the predictions of different formalisms. Binding effects due to short range correlations in deuteron are discussed as well.Comment: 18 pages (LaTex) + 10 postscript figs (available on request

Diffraction at HERA, Color Opacity and Nuclear Shadowing

The QCD factorization theorem for diffractive processes in DIS is used to derive formulae for the leading twist contribution to the nuclear shadowing of parton distributions in the low thickness limit. Based on the current analyzes of diffraction at HERA we find that the average strength of the interactions which govern diffraction in the gluon sector at $x \le 10^{-3}, Q_0=2 GeV$ is ~50 mb. This is 3 times larger than in the quark sector and suggests that applicability of DGLAP approximation requires significantly larger $Q_0$ in the gluon sector. We use this information to estimate quark and gluon shadowing for heavy nuclei and to calculate its$Q^2$ depen- dence. For A~200 the amount of the gluon shadowing: $G_A/AG_N\sim 0.25-0.4$ at $x<10^{-3},Q=2GeV$ is sensitive to the probability of the small size configurations within wave function of the gluon "partonometer" at the $Q_0$ scale. At this scale for $A\sim 200$ the nonperturbative contribution to the gluon density is reduced by a factor of 4-5 at $x \le 10^{-3}$ unmasking PQCD physics in the gluon distribution of heavy nuclei. Such shadowing would strongly modify the first stage of the heavy ion collisions at LHC, and would lead to large color opacity effects in $eA$ collisions at x<0.001. The leading twist contribution to the cross section of the coherent $J/\psi$ production off $A\ge 12$ nuclei at $\sqrt s \ge 70$ GeV is strongly reduced as compared to the naive color transparency expectations. The Gribov black body limit for $F_{2A}(x,Q^2)$ is extended to the case of the gluon distributions in nuclei and shown to be relevant for the HERA kinematics of $eA$ collisions. Properties of the final states are also briefly discussed.Comment: 42 pages, 10 figures, final version to appear in Europ. Jour.of Phys., discussion of a number of issues is substantially extended, two figures and several references are adde

Fading out of J/psi color transparency in high energy heavy ion peripheral collisions

We provide predictions for the J/psi coherent production in the peripheral heavy ion collisions at LHC and at RHIC using the leading twist model of nuclear shadowing based on the QCD factorization theorem for diffraction and the HERA hard diffraction data. We demonstrate that for the LHC kinematics this model leads to a bump-shape distribution in rapidity which is suppressed overall as compared to the expectations of the color transparency regime by a factor 6. This is significantly larger suppression than that expected within the impact parameter eikonal model. Thus we show that the interaction of spatially small wave package for which the total cross section of interaction with nucleons is small is still strongly shadowed by nuclear medium in high energy processes.Comment: 13 pages, 7 figure

Searching for Color Coherent Effects at Intermediate Q2Q^2 via Double Scattering Processes

We propose that measuring the $Q^2$ dependence of the number of final-state interactions of the recoil protons in quasi-elastic electron scattering from light nuclei is a new method to investigate Color Coherent effects at {\bf intermediate} values of $Q^2$ ({$\sim$ few $(GeV/c)^2$}). This is instead of measuring events without final-state interactions. Our calculations indicate that such measurements could reveal significant color transparency effects for the highest of the energies initially available at CEBAF. Measurements that detect more than one hadron in the final state, which require the use of large acceptance ($4\pi$) detectors, are required.Comment: 19 pages in RevTex, 5 postscript figures available from [email protected]

Photoproduction of Quarkonium in Proton-Proton and Nucleus-Nucleus Collisions

We discuss the photoproduction of $\Upsilon$ and $J/\psi$ at high energy $\bar{p}p$, $pp$ and heavy ion colliders. We predict large rates in $\bar{p}p$ interactions at the Fermilab Tevatron %and in heavy-ion interactions at the CERN LHC. These reactions can be and in $pp$ and heavy-ion interactions at the CERN LHC. The $J/\psi$ is also produced copiously at RHIC. These reactions can be used to study the gluon distribution in protons and heavy nuclei. We also show that the different CP symmetries of the initial states lead to large differences in the transverse momentum spectra of mesonsComment: 4 pgs. with 3 figure

Charm production in antiproton-nucleus collisions at the J/ψJ/\psi and the ψ′\psi' thresholds

We discuss the production of charmonium states in antiproton-nucleus collisions at the $\psi'$ threshold. It is explained that measurements in $\bar p A$ collisions will allow to get new information about the strengths of the inelastic $J/\psi N, \psi'N$ interaction, on the production of $\Lambda_c$ and $\bar{D}$ in charmonium-nucleon interactions and for the first time about nondiagonal transitions $\psi' N\to J/\psi N$. The inelastic $J/\psi$-nucleon cross section is extracted from the comparison of hadron-nucleus collisions with hadron-nucleon collisions. We extract the total $J/\psi$ nucleon cross section from photon-nucleon collisions by accounting for the color transparency phenomenon within the frame of the GVDM (Generalized Vector meson Dominance Model). We evaluate also within the GVDM the inelastic $\psi'$-nucleon cross section as well as the cross section for the nondiagonal transitions. Predictions for the ratio of $J/\psi$ to $\psi'$ yields in antiproton-nucleus scatterings close to the threshold of $\psi'$ production for different nuclear targets are presented.Comment: 13 pages, 10 figures, typos corrected, some discussion adde

A fresh look at diffractive J/ψJ/\psi photoproduction at HERA, with predictions for THERA

We quantify perturbative and non-perturbative QCD effects in the exclusive $J/\psi$-photoproduction cross section, and in the shrinkage of the differential cross section with respect to momentum transfer, $t$. We predict that in the high energy THERA region there will always be a significant contribution to this process that rises quickly with energy. This implies that the taming of the rise of the cross section with energy, due to both the expansion of spatially-small fluctuations in the photon and to higher twist effects, is rather gradual.Comment: Published version, 29 pages, 16 figures, uses JHEP.cls. Substantially rewritten to better emphasize the generality of the results in response to the referee's comments. Predictions for MRST LO partons added, calculations and discussion of the real part of the amplitude and of alpha prime improved. Five of the original figures modified. Two new plots, of the dipole cross section for two different values of parameter lambda, and of energy dependence of alpha prime, added. Three additional references include