Electroproduction of the Λ(1520) hyperon

Abstract

The reaction ep⃗e′K+Λ(1520) with Λ(1520)→p′K- was studied at electron beam energies of 4.05, 4.25, and 4.46 GeV, using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The cosθK+, φK+, Q2, and W dependencies of Λ(1520) electroproduction are presented for the kinematic region 0.9<Q2<2.4 GeV2 and 1.95<W<2.65 GeV. Also, the Q2 dependence of the Λ(1520) decay angular distribution is presented for the first time. The cosθK+ angular distributions suggest t-channel diagrams dominate the production process. Fits to the Λ(1520) t-channel helicity frame decay angular distributions indicate the mz=±1/2 parentage accounts for about 60% of the total yield, which suggests this reaction has a significant contribution from t-channel processes with either K+ exchange or longitudinal coupling to an exchanged K*. The Q2 dependence of the Λ(1520) production cross section is the same as that observed for Λ(1116) photo- and electroproduction

Near-ThresholdΛ(1520)Production by theγ→p→K+Λ(Kohri1, Ahn2, Ahn3 et al. 2010Phys. Rev. Lett.Self Cite542592View full textAdd to dashboardCite

“…energies [10]. Recent K þ Ãð1520Þ electroproduction data at W ¼ 1:95-2:65 GeV show that contributions from K and K Ã exchanges are roughly equal [11]. Therefore, additional data with new observables are needed for solving this controversial situation.…”

Photoproduction of γp→K+Λ*(1520) and decay of ΛYu1, Kong2 2017Phys. Rev. C120300View full textAdd to dashboardCite

“…By using the t-channel helicity frame of Λ * for the calculation of the density matrix elements ρ λλ ′ , we show that the numerical analysis of the LAMP2 and LEPS data on the I(θ * ) is consistent with the dominance of the helicity ±3/2 of Λ * decay due to the strong contribution of the ρ 33 by the contact term in addition to the K * + K * 2 contributions. This finding is, however, contradictory to the experiments in the SAPHIR [4] and the CLAS albeit the latter case of electroproduction has more reasons to be [14]. Therefore, such a contradiction in explaining the I(θ * ) should be clarified in experiments by the precise measurements of the ρ 33 and ρ 11 in a specified G.-J.…”

“…In recent experiments it has been another topic to measure the decay angular distribution of the K − in the Λ * (1520) → K − p decay process, since the observable is expected to provide information about spin exchanges of K and K * in understanding the production mechanism. Nevertheless, however, the interpretation of it seems not clear yet, because the recent data on the photoproduction [4] and the result from electroproduction process [14] lead to a conclusion contradictory to the LAMP2 data.…”

“…2 (b) where the K * exchange of the natural parity in the photoproduction leads to the decay of the Λ * with helicity S z = ± 3 2 , which corresponds to the term of sin 2 θ * , whereas the K exchange of unnatural parity to the S z = ± 1 2 corresponding to the term of 1 3 + cos 2 θ * . Figure 3 shows the density matrix elements ρ 33 and ρ 11 calculated in the t-channel helicity frame of Λ * where the z-axis is taken to be the direction opposite to the target proton momentum [2,14,23], as presented in the Appendix. At the θ ≈ 0 • and at E γ = 3.8 GeV, together with the small negative values for the Re[ρ 32 ] and Re[ρ 3−1 ], we obtain ρ 33 = 0.375 and ρ 11 = 0.125, which are consistent with those extracted from the LAMP2 data given in Table 1 of Ref.…”

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

“…Pioneering measurements at Cornell [21] and CEA [22] will not be discussed. There is also a Λ(1520) electroproduction result from CLAS [23] at Q 2 > 0.9 GeV/c 2 that we will not discuss here.…”