High-Energy Photoproduction of Neutral Rho Mesons

Ultra-peripheral heavy-ion collisions with the CMS experiment

“…This is currently a subject of strong interest since it dominates the initial state of heavy ion collisions. Photoproduction of vector mesons has been studied with lepton beams [5] and later at the electron-proton collider HERA [6] [7]. The STAR and PHENIX collaborations at RHIC have studied ρ 0 and J/ψ production in ultraperipheral AuAu collisions at √ s NN = 200 GeV [8] [9].…”

"Regeneration" Effects inω−ϕProduction

“…In any case, their inclusion is extremely difficult because it would require knowledge of the phase of the amplitude A TrJv^piV-One would then have to resort to such unreliable models as those of Regge or SU (6). It is amusing to note that if one describes the p-production amplitude by a one-pion exchange, then the isospin factors are such as to cancel the According to current ideas, 1 the a; and cp mesons are a coherent mixture of a pure SU(3) octet state <p 0 and a pure SU(3) singlet co 0 .…”

“…5 E. S. Abers, H. Burkhardt, V. L. Teplitz, and C. Wilkin, Nuovo Cimento 42A, 365 (1966). 6 We shall, throughout, keep to the notation of Ref. 2.…”

“…/' (6) 1/2X = <l/2x> ay /+ (1/2X) (a cos20 + 0^ sin20 ), (cr's are the usual Pauli matrices.) x^/ ^ are the effective mean free paths for the combinations co' = co cosOff + cpsinOtf, cp' = -oo sin6N+ cp xcosOtf, which are diagonal in nuclear matter, with ON the "mixing angle" in nuclear matter.…”

Particle Production by 2.9-BeV Protons Incident on Beryllium and Platinum

“…Evidence for coherent photoproduction reactions with complex nuclei has also been reported. 25 In the analysis below we first compare, for each particle, the experimental momentum spectra (Figs. 5-6) to the corresponding data in hydrogen.…”