Photoproduction ofωmesons off nuclei and impact of polarization on the meson-nucleon interaction

Abstract

7We use photoproduction of ω mesons off complex nuclei to study interactions of transversely and

Vector mesons production off nuclei at the new planned QCD facility at CERN

“…3). This data obtained by HERMES collaboration at Q 2 > 1 (GeV/c) 2 and energy 3 GeV < W < 6.3 GeV and such behavior has been explained [22] by huge contribution of unnatural parity exchange in transition amplitude γ * T → ω T . The measurement of ω photoproduction at smaller photon virtuality Q 2 < 1(GeV /c) 2 and higher energies using the COMPASS-like possibilities leads to better…”

“…Whereas in the charge exchange reaction π − + p → V + n with dominating pion exchange vector mesons are produced mainly longitudinally polarized (helicity λ = 0) the investigation of their production off nuclei π − + A → V + A (A is the nuclear excitation or its break-up products) allows to extract the total cross section of the longitudinally polarized vector meson interaction with nucleon σ L (V N), a value of which has not yet been measured. Such measurements are of a current interest as they are complement to investigations of vector mesons photoproduction off nuclei [2] the experimental realization of which is recently proposed at JLAB [3,4] to be done using the possibilities of the GlueX detector at Hall D, JLAB. The obvious advantage of the vector mesons production by hadron beam compared with vector mesons photoproduction is that in the charge exchange process π − (K − ) + A → V + A the main part of vector mesons is longitudinally polarized unlike vector mesons photoproduction, where due to the s-channel helicity conservation ρ, φ mesons are produced mainly transversely polarized and only a part of ω mesons at JLAB energies (due to pion exchange) is longitudinally polarized.…”

Probing Invisible Vector Meson Decays with NA64 and LDMX

“…[118], which were motivated by quark model estimates and chosen to adequately describe coherent photoproduction data. The results do not depend strongly on the nuclear density model, but we use a Woods-Saxon distribution [124], n(r) ∝ 1 1 + e (r−c)/a (A3)…”

Vector mesons polarization versus color transparency

“…Recently we proposed [11,12] to measure the ω mesons photoproduction on a set of nuclei at photons energies 5GeV ≤ E γ ≤ 10GeV available at Jefferson Lab. The deal is that incoherent photoproduction of ω mesons off nuclear targets is a unique way to get information on the possible dependence of strong interaction on the polarization of vector particle.…”