相关论文: Single Pseudoscalar Meson Production in Diffractiv…
We consider exclusive $\pi^0$ production in ep-scattering. At high energies odderon and photon exchange contribute. The photon exchange contribution is evaluated exactly using data for the total virtual photon-proton absorption cross…
We investigate the reaction $e p \to e PS X$ where PS denotes a pseudoscalar meson $\pi^0, \eta, \eta'$, or $\eta_c$ and X either a proton or resonance or continuum states into which the proton can go by diffractive excitation. At high…
In this report diffractive high energy reactions are discussed in a functional integral approach where hadronic amplitudes are calculated from vacuum expectation values of lightlike Wegner-Wilson loops. In the first part we calculate…
Selected recent results from the H1 and ZEUS experiments are reviewed, illustrating some of the many facets of ``meson physics'' at the HERA ep collider. The results cover exclusive elastic and proton-dissociative diffractive vector meson…
Using a set of new odderon states, we calculate their contribution to the diffractive eta_c photo- and electroproduction process. Compared to previous simple 3-gluon exchange calculations we find an enhancement of about one order of…
The rich structure of photon-exchange processes at hadron colliders is studied. We discuss central vector meson production pp --> p + J/psi + p, W production pp --> p + W + X and mu+ mu- production. Each process has distinct, and large,…
We investigate contributions to diffractive scattering, which are odd under C- and P-parity. Comparison of p-$\bar p$ and p-p scattering indicates that these odderon contributions are very small and we show how a diquark clustering in the…
We investigate the exclusive electroproduction of pi^+ mesons from nucleons. To leading twist, leading order alpha_s accuracy the corresponding production amplitude can be decomposed into pseudovector and pseudoscalar parts. Both can be…
In this talk estimates are presented of the odderon contributions to the exclusive J/psi and Upsilon production cross-sections at the Tevatron and the Large Hadron Collider. The obtained cross-sections are compared to cross-sections of the…
Exclusive production of a $\eta_c$ pseudo-scalar meson in $\gamma^{(*)} + p \to \eta_c + p$ scattering at high energies involves a ${\cal C}$-odd exchange in the $t$-channel. We formulate the description of this process within the…
There seem to be recently an evidence for $C = -1$ odderon exchange in proton-proton elastic scattering at high energies. Here we discuss three different central-exclusive-production processes $pp \to pp (\phi \to K^{+}K^{-})$, $pp \to pp…
A study has been made of pseudoscalar mesons produced centrally in pp interactions. The results show that the eta and etaprime appear to have a similar production mechanism which differs from that of the pi0. The production properties of…
We discuss exclusive central diffractive production of scalar ($f_{0}(980)$, $f_{0}(1370)$, $f_{0}(1500)$), pseudoscalar ($\eta$, $\eta'(958)$), and vector ($\rho^{0}$) mesons in proton-proton collisions. The amplitudes are formulated in…
In diffractive hadronic scattering processes, the Pomeron trajectory, originating from Regge theory, significantly contributes to the behavior of the total and differential cross sections; the same holds for the description of the proton…
We discuss exclusive central diffractive production of scalar ($f_{0}(980)$, $f_{0}(1370)$, $f_{0}(1500)$), pseudoscalar ($\eta$, $\eta'(958)$), and vector ($\rho^{0}$) mesons in proton-proton collisions. We show that high-energy central…
Experiments that study the photoproduction of pseudoscalar mesons; pions, etas and kaons, have the potential to increase our knowledge of baryon and hyperon resonance properties. Recent experiments at JLab, Mainz, GRAAL, and Bonn are…
Off-diagonal parton distributions occur in several hard exclusive reactions. They extend the study of hadron structure beyond what can be learned from ordinary distributions and have a particularly rich spin structure. The hard scattering…
Diffractive photoproduction of $\eta_c$ is an important process to study the effect of Odderon, whose existence is still not confirmed in experiment. A detailed interpretation of Odderon in QCD, i.e., in terms of gluons is also…
We calculate the cross section of diffractive charge-parity C=+1 neutral meson production in virtual photon proton collision at high energies. Due to the opposite C-parities of photon and meson M (M = eta_C, pi^0, a_2) this process probes…
The hard exclusive electroproduction of $\pi^0,\eta,\eta'$ mesons by the longitudinal photons is considered. We calculate the ratios of the $\pi^0 : \eta : \eta'$ yields for the electroproduction processes off nucleons and deuterons based…