First Search for Dyons with the Full MoEDAL Trapping Detector in 13 TeV pp Collisions

Acharya, B.; Alexandre, J.; Benes, P.; Bergmann, B.; Bernabéu, J.; Bevan, A.; Branzas, H.; Burian, P.; Campbell, M.; Cecchini, S.; Cho, Y. M.; de Montigny, M.; De Roeck, A.; Ellis, J. R.; El Sawy, M.; Fairbairn, M.; Felea, D.; Frank, M.; Hays, J.; Hirt, A. M.; Janecek, J.; Kalliokoski, M.; Korzenev, A.; Lacarrère, D. H.; Leroy, C.; Levi, G.; Lionti, A.; Mamuzic, J.; Maulik, A.; Margiotta, A.; Mauri, N.; Mavromatos, N. E.; Mermod, P.; Mieskolainen, M.; Millward, L.; Mitsou, V. A.; Orava, R.; Ostrovskiy, I.; Ouimet, P.-P.; Papavassiliou, J.; Parker, B.; Patrizii, L.; Păvălaş, G. E.; Pinfold, J. L.; Popa, L. A.; Popa, V.; Pozzato, M.; Pospisil, S.; Rajantie, A.; Ruiz de Austri, R.; Sahnoun, Z.; Sakellariadou, M.; Santra, A.; Sarkar, S.; Semenoff, G.; Shaa, A.; Sirri, G.; Sliwa, K.; Soluk, R.; Spurio, M.; Staelens, M.; Suk, M.; Tenti, M.; Togo, V.; Tuszyński, J. A.; Upreti, A.; Vento, V.; Vives, O.; Wall, A.

doi:10.1103/PhysRevLett.126.071801

The production of 𝜂 and 𝜂′ mesons is studied in proton-proton and proton-lead collisions collected with the LHCb detector. Proton-proton collisions are studied at center-of-mass energies of 5.02 and 13TeV and proton-lead collisions are studied at a center-of-mass energy per nucleon of 8.16TeV. The studies are performed in center-of-mass (c.m.) rapidity regions 2.5<𝑦c.m.<3.5 (forward rapidity) and −4.0<𝑦c.m.<−3.0 (backward rapidity) defined relative to the proton beam direction. The 𝜂 and 𝜂′ production cross sections are measured differentially as a function of transverse momentum for 1.5<𝑝T<10GeV and 3<𝑝T<10GeV, respectively. The differential cross sections are used to calculate nuclear modification factors. The nuclear modification factors for 𝜂 and 𝜂′ mesons agree at both forward and backward rapidity, showing no significant evidence of mass dependence. The differential cross sections of 𝜂 mesons are also used to calculate 𝜂/𝜋0 cross-section ratios, which show evidence of a deviation from the world average. These studies offer new constraints on mass-dependent nuclear effects in heavy-ion collisions, as well as 𝜂 and 𝜂′ meson fragmentation.

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