Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userExclusive production of $rho$-mesons in high-energy factorization at HERA and EIC
116
0
0.0
(
0
)
Added by
Francesco Giovanni Celiberto
Publication date
2021
fields
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
We calculate cross sections for the exclusive diffractive leptoproduction of $rho$-mesons, $gamma^*~p~to~rho~p$, within the framework of high-energy factorization. Cross sections for longitudinally and transversally polarized mesons are shown. We employ a wide variety of unintegrated gluon distributions available in the literature and compare to HERA data. The resulting cross sections strongly depend on the choice of unintegrated gluon distribution. We also present predictions for the proton target in the kinematics of the Brookhaven EIC.
rate research
Read More
Exclusive production of $rho^0$ and $J/psi$ mesons in e^+ p collisions has been studied with the ZEUS detector in the kinematic range $0.25 < Q^2 < 50 GeV^2, 20 < W < 167 GeV$ for the $rho^0$ data and $2 < Q^2 < 40 GeV^2, 50 < W < 150 GeV$ for the $J/psi$ data. Cross sections for exclusive $rho^0$ and $J/psi$ production have been measured as a function of $Q^2, W$ and $t$. The spin-density matrix elements $r^{04}_{00}, r^1_{1-1}$ and $Re r^{5}_{10}$ have been determined for exclusive $rho^0$ production as well as $r^{04}_{00}$ and $r^{04}_{1-1}$ for exclusive $J/psi$ production. The results are discussed in the context of theoretical models invoking soft and hard phenomena.
We present a non-perturbative QCD calculation of high-energy diffractive photo- and leptoproduction of vector mesons $rho$, $rho$ and $rho$ on a nucleon. The initial photon splits up in a $qbar{q}$-dipole and transforms into a vector meson by scattering on the quark-diquark nucleon. The dipole-dipole scattering amplitude is provided by the non-perturbative model of the stochastic QCD vacuum, the wave functions result from considerations on the light-cone. We assume the physical $rho$- and $rho$-states to be mixed states of an active 2S-excitation and a rest whose coupling to the photon is suppressed. We obtain good agreement with the experimental data and get an understanding of the markedly different spectrum in the $pi^+pi^-$-invariant mass for photoproduction and $e^+e^-$-annihilation.
Recent results obtained at HERA on deeply virtual Compton scattering and exclusive vector meson production are reviewed, with the emphasis on the transition from soft to hard diffraction and on spin dynamics.
Exclusive photoproduction of $rho^0(770)$ mesons is studied using the H1 detector at the $ep$ collider HERA. A sample of about 900000 events is used to measure single- and double-differential cross sections for the reaction $gamma p to pi^{+}pi^{-}Y$. Reactions where the proton stays intact (${m_Y{=}m_p}$) are statistically separated from those where the proton dissociates to a low-mass hadronic system ($m_p{<}m_Y{<}10$ GeV). The double-differential cross sections are measured as a function of the invariant mass $m_{pipi}$ of the decay pions and the squared $4$-momentum transfer $t$ at the proton vertex. The measurements are presented in various bins of the photon-proton collision energy $W_{gamma p}$. The phase space restrictions are $0.5 < m_{pipi} < 2.2$ GeV, ${vert tvert < 1.5}$ GeV${}^2$, and ${20 < W_{gamma p} < 80}$ GeV. Cross section measurements are presented for both elastic and proton-dissociative scattering. The observed cross section dependencies are described by analytic functions. Parametrising the $m_{pipi}$ dependence with resonant and non-resonant contributions added at the amplitude level leads to a measurement of the $rho^{0}(770)$ meson mass and width at $m_rho = 770.8 {}^{+2.6}_{-2.7}$ (tot) MeV and $Gamma_rho = 151.3 {}^{+2.7}_{-3.6}$ (tot) MeV, respectively. The model is used to extract the $rho^0(770)$ contribution to the $pi^{+}pi^{-}$ cross sections and measure it as a function of $t$ and $W_{gamma p}$. In a Regge asymptotic limit in which one Regge trajectory $alpha(t)$ dominates, the intercept $alpha(t{=}0) = 1.0654 {}^{+0.0098}_{-0.0067}$ (tot) and the slope $alpha^prime(t{=}0) = 0.233 {}^{+0.067 }_{-0.074 }$ (tot) GeV${}^{-2}$ of the $t$ dependence are extracted for the case $m_Y{=}m_p$.
Exclusive rho rho production in two-photon collisions between a quasi-real, gamma, and a virtual, gamma*, photons is studied at LEP at centre-of-mass energies 89 GeV < sqrt{s} < 209 GeV with a total integrated luminosity of 854.7 pb-1. The cross sections of the gamma gamma* -> rho rho processes are determined as a function of the photon virtuality, Q^2, and the two-photon centre-of-mass energy, Wgg, in the kinematic region: 0.2 GeV^2 < Q^2 < 30 GeV^2 and 1.1 GeV < Wgg < 3 GeV.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
