KþK− pairs may be produced in photonuclear collisions, either from the decays of photoproduced ϕð1020Þ mesons or directly as nonresonant KþK− pairs. Measurements of KþK− photoproduction probe the couplings between the ϕð1020Þ and charged kaons with photons and nuclear targets. The kaon-proton scattering occurs at energies far above those available elsewhere. We present the first measurement of coherent photoproduction of KþK− pairs on lead ions in ultraperipheral collisions using the ALICE detector, including the first investigation of direct KþK− production. There is significant KþK− production at low transverse momentum, consistent with coherent photoproduction on lead targets. In the mass range 1.1 < M KK < 1.4 GeV=c2 above the ϕð1020Þ resonance, for rapidity jy KK j < 0.8 and p T;KK < 0.1 GeV=c, the measured coherent photoproduction cross section is dσ=dy ¼ 3.37 0.61ðstatÞ 0.15ðsystÞ mb. The center-of-mass energy per nucleon of the photon-nucleus (Pb) system WγPb;n ranges from 33 to 188 GeV, far higher than previous measurements on heavy-nucleus targets. The cross section is larger than expected for ϕð1020Þ photoproduction alone. The mass spectrum is fit to a cocktail consisting of ϕð1020Þ decays, direct KþK− photoproduction, and interference between the two. The confidence regions for the amplitude and relative phase angle for direct KþK− photoproduction are presented

Photoproduction of K+K- Pairs in Ultraperipheral Collisions / Acharya, S., Adamová, D., Aglieri Rinella, G., Agnello, M., Agrawal, N., Ahammed, Z., Ahmad, S., Ahn, S. U., Ahuja, I., Akindinov, A., Al-Turany, M., Aleksandrov, D., Alessandro, B., Alfanda, H. M., Alfaro Molina, R., Ali, B., Alici, A., Alizadehvandchali, N., Alkin, A., Alme, J., et al.. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - 132:22(2024), pp. 1-13. [10.1103/physrevlett.132.222303]

Photoproduction of K+K- Pairs in Ultraperipheral Collisions

Agnello, M.;Balbino, A.;Bufalino, S.;Catalano, F.;Ciacco, M.;Ferrero, C.;Gioachin, G.;
2024

Abstract

KþK− pairs may be produced in photonuclear collisions, either from the decays of photoproduced ϕð1020Þ mesons or directly as nonresonant KþK− pairs. Measurements of KþK− photoproduction probe the couplings between the ϕð1020Þ and charged kaons with photons and nuclear targets. The kaon-proton scattering occurs at energies far above those available elsewhere. We present the first measurement of coherent photoproduction of KþK− pairs on lead ions in ultraperipheral collisions using the ALICE detector, including the first investigation of direct KþK− production. There is significant KþK− production at low transverse momentum, consistent with coherent photoproduction on lead targets. In the mass range 1.1 < M KK < 1.4 GeV=c2 above the ϕð1020Þ resonance, for rapidity jy KK j < 0.8 and p T;KK < 0.1 GeV=c, the measured coherent photoproduction cross section is dσ=dy ¼ 3.37 0.61ðstatÞ 0.15ðsystÞ mb. The center-of-mass energy per nucleon of the photon-nucleus (Pb) system WγPb;n ranges from 33 to 188 GeV, far higher than previous measurements on heavy-nucleus targets. The cross section is larger than expected for ϕð1020Þ photoproduction alone. The mass spectrum is fit to a cocktail consisting of ϕð1020Þ decays, direct KþK− photoproduction, and interference between the two. The confidence regions for the amplitude and relative phase angle for direct KþK− photoproduction are presented
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11583/2990267