CLAS Physics Database

Spokesperson
Curtis A. Meyer
Abstract
High-statistics measurements of differential cross sections and spin density matrix elements for the reaction γp -> φp have been made using the CLAS detector at Jefferson Lab. We cover center-of-mass energies (sqrt(s)) from 1.97 to 2.84 GeV, with an extensive coverage in the φ production angle. The high statistics of the data sample made it necessary to carefully account for the interplay between the φ natural lineshape and effects of the detector resolution, that are found to be comparable in magnitude. We study both the charged- (φ -> K+K-) and neutral- (φ -> K0SK0L) KK decay modes of the φ. Further, for the charged mode, we differentiate between the cases where the final K- track is directly detected or its momentum reconstructed as the total missing momentum in the event. The two charged-mode topologies and the neutral-mode have different resolutions and are calibrated against each other. Extensive usage is made of kinematic fitting to improve the reconstructed φ mass resolution. Our nal results are reported in 10- and mostly 30-MeV-wide sqrt(s) bins for the charged- and the neutral-mode, respectively. Possible e ects from K+Λ* channels with pKK final-states are discussed. These present results constitute the most precise and extensive φ photoproduction measurements to date and in conjunction with the ω photoproduction results recently published by CLAS, will greatly improve our understanding of low energy vector meson photoproduction.
Comment
The data were obtained using real photons produced via bremsstrahlung from a 4.023-GeV electron beam
Publication
  1. B.Dey, C.A.Meyer, M.Bellis, M.Williams, and CLAS Collaboration Data analysis techniques, differential cross sections, and spin density matrix elements for the reaction γp -> φp // arXiv:1403.2110v2 [nucl-ex]
Quantities
dσ/dcos(θ) ρ00,0 ρ01,0 ρ01,-1

Measurements

ID Quantity Beam Target Final state Q2min,
GeV2
Q2max,
GeV2
Wmin,
GeV
Wmax,
GeV
E63M1 dσ/dcos(θ) γ p φ p 0.0 0.0 1.985 2.835
E63M2 dσ/dcos(θ) γ p φ p 0.0 0.0 1.985 2.835
E63M3 dσ/dcos(θ) γ p φ p 0.0 0.0 1.985 2.815
E63M4 ρ00,0 γ p φ p 0.0 0.0 1.985 2.835
E63M5 ρ01,0 γ p φ p 0.0 0.0 1.985 2.835
E63M6 ρ01,-1 γ p φ p 0.0 0.0 1.985 2.835
E63M7 ρ00,0 γ p φ p 0.0 0.0 1.985 2.835
E63M8 ρ01,0 γ p φ p 0.0 0.0 1.985 2.835
E63M9 ρ01,-1 γ p φ p 0.0 0.0 1.985 2.835
E63M10 ρ00,0 γ p φ p 0.0 0.0 1.985 2.815
E63M11 ρ01,0 γ p φ p 0.0 0.0 1.985 2.815
E63M12 ρ01,-1 γ p φ p 0.0 0.0 1.985 2.815