Exclusive ϱ0 and φ muoproduction at large Q2

Abstract

Exclusive 0 and muoproduction on deuterium, carbon and calcium has been studied in the kinematic range 2 < Q 2 < 25 GeV 2 and 40 < < 180 GeV . We discuss the Q 2 dependence of the cross sections, the transverse momentum distributions for the vector mesons, the decay angular distributions and, in the case of the 0 , n uclear e ects. The data for 0 production are compatible with a di ractive mechanism. The distinct features of production are a smaller cross section and less steep p 2 t distributions than those for the 0 mesons. ||||||||||||||||||For footnotes see next page.

Unified model of exclusiveρ0,φ, andJ/ψelectroproduction

“…W dependence of the ρ -meson cross-section for various Q 2 in model S2. The data are from: NMC [48]; H1 [64]; and ZEUS [62]. : J/ψ meson t dependence, Q 2 = 0, 91 < W < 110 GeV.…”

Rho zero electroproduction and the hadronic contribution to deeply virtual compton scattering

“…Figure 3: The Q 2 -dependence of the longitudinal to transverse ratio compared with high energy data from H1 [12,34,35] and ZEUS [11,32,36], and low energy data from CHIO [37], E665 [38] and NMC [33]. Figure 4: W -dependence compared with data from H1 [12], ZEUS [11] and NMC [33]. The use of the open and filled markers is only to indicate to which value of Q 2 the data points belong.…”

“…‡ For further details, see [28] Figure 2: The dependence of total cross section on Q 2 0 compared with high energy data from H1 [12] and ZEUS [11,31,32], and lowenergy data from NMC [33]. Figure 3: The Q 2 -dependence of the longitudinal to transverse ratio compared with high energy data from H1 [12,34,35] and ZEUS [11,32,36], and low energy data from CHIO [37], E665 [38] and NMC [33]. Figure 4: W -dependence compared with data from H1 [12], ZEUS [11] and NMC [33].…”

“…The effect is consistent both at high and low energy and allows us to fix Q 2 0 ≈ 0.9 GeV 2 , which is a reasonable value. ‡ For further details, see [28] Figure 2: The dependence of total cross section on Q 2 0 compared with high energy data from H1 [12] and ZEUS [11,31,32], and lowenergy data from NMC [33]. Figure 3: The Q 2 -dependence of the longitudinal to transverse ratio compared with high energy data from H1 [12,34,35] and ZEUS [11,32,36], and low energy data from CHIO [37], E665 [38] and NMC [33].…”

Factorization of the dependence in electroproduction of vector mesons

“…Fig. 8 shows the experimental ratio [29,31,35,36] between longitudinal and transverse cross sections in ρ electroproduction, compared to the ratio of longitudinal to transverse squared overlap strengths. In the ratio, the specific dynamics of the process of interaction of the q −q dipoles with the proton cancels out, so that a clear view is obtained of the self-contained role of the photon-meson wave function overlap.…”