Near-Threshold Photoproduction ofΛ(1520)from Protons and Deuterons

Abstract

Photoproduction of Lambda(1520) with liquid hydrogen and deuterium targets was examined at photon energies below 2.4 GeV in the SPring-8 LEPS experiment. For the first time, the differential cross sections were measured at low energies and with a deuterium target. A large asymmetry of the production cross sections from protons and neutrons was observed at backward K+/0 angles. This suggests the importance of the contact term, which coexists with t-channel K exchange under gauge invariance. This interpretation was compatible with the differential cross sections, decay asymmetry, and photon beam asymmetry measured in the production from protons at forward K+ angles.

Near-ThresholdΛ(1520)Production by theγ→p→K+Λ(Kohri1, Ahn2, Ahn3 et al. 2010Phys. Rev. Lett.Self Cite552592View full textAdd to dashboardCite

“…However, the angular distribution of the bump is not well reproduced. The theoretical calculations estimate the cross sections at backward K þ angles to be about 0:7 b that overestimates the experimental cross sections [25] by 2-3 times. The bump is not observed in the cross sections of the backward K þ angles [25].…”

Differential photoproduction cross sections of theΣ0(1385),Λ(1405), andMoriya1, Schumacher2, Adhikari3 et al. 2013Phys. Rev. CSelf Cite

“…The only data comparison available is the LEPS Collaboration result by Niiyama et al [24] [13]. The hollow circular points show separate LEPS results [14]; in the lowest W bin they are for W = 2.01 GeV (red), 2.03 GeV (blue), and 2.05 GeV (green).…”

“…In more recent times, the LEPS Collaboration has looked at photoproduction of this hyperon in the energy region 1.9 < E γ < 2.8 GeV using a forward-angle spectrometer [13,14]. They showed that the cross section is forward peaked, and that this behavior is more consistent with a model dominated by a gauge-invariance-preserving contact term [15,16], and less consistent with models dominated by t−channel vector meson K * exchange [17,18].…”

“…Ref. [13] measured the differential cross section in several final states using various methods that were presented as equivalently accurate. These points are shown as open squares in Fig.…”

Photoproduction of $\pi^{-}\Delta^{++}$ and $\pi^{+}\Delta^{0}$ on the proton for the comparison of $\bar{u}u$ and $\bar{d}d$ productions

“…The LEPS spectrometer was designed to efficiently detect φ -mesons decaying to K + and K − at forward angles [1,2,3,4,5]. Not only φ but also K + photoproduction reactions are extensively studied [6,7,8,9,10,11,12,13].…”