학술논문
First determination of the $\rho $ parameter at $\sqrt{s} = 13$ TeV -- probing the existence of a colourless three-gluon bound state
Document Type
Working Paper
Author
TOTEM Collaboration; Antchev, G.; Aspell, P.; Atanassov, I.; Avati, V.; Baechler, J.; Barrera, C. Baldenegro; Berardi, V.; Berretti, M.; Bossini, E.; Bottigli, U.; Bozzo, M.; Bruce, R.; Burkhardt, H.; Cafagna, F. S.; Catanesi, M. G.; Csanád, M.; Csörgő, T.; Deile, M.; De Leonardis, F.; D'Orazio, A.; Doubek, M.; Druzhkin, D.; Eggert, K.; Eremin, V.; Ferro, F.; Fiergolski, A.; Garcia, F.; Morales, H. Garcia; Georgiev, V.; Giani, S.; Grzanka, L.; Hammerbauer, J.; Heino, J.; Helander, P.; Isidori, T.; Ivanchenko, V.; Janda, M.; Karev, A.; Kašpar, J.; Kopal, J.; Kundrát, V.; Lami, S.; Latino, G.; Lauhakangas, R.; Linhart, R.; Lindsey, C.; Lokajíček, M. V.; Losurdo, L.; Vetere, M. Lo; Rodríguez, F. Lucas; Macrí, M.; Malawski, M.; Mereghetti, A.; Minafra, N.; Minutoli, S.; Mirarchi, D.; Naaranoja, T.; Nemes, F.; Niewiadomski, H.; Novák, T.; Oliveri, E.; Oljemark, F.; Oriunno, M.; Österberg, K.; Palazzi, P.; Passaro, V.; Peroutka, Z.; Procházka, J.; Quinto, M.; Radermacher, E.; Radicioni, E.; Ravotti, F.; Redaelli, S.; Robutti, E.; Royon, C.; Ruggiero, G.; Saarikko, H.; Salvachua, B.; Scribano, A.; Siroky, J.; Smajek, J.; Snoeys, W.; Stefanovitch, R.; Sziklai, J.; Taylor, C.; Tcherniaev, E.; Turini, N.; Vacek, V.; Valentino, G.; Welti, J.; Wenninger, J.; Williams, J.; Wyszkowski, P.; Zich, J.; Zielinski, K.
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Subject
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Abstract
The TOTEM experiment at the LHC has performed the first measurement at $\sqrt{s} = 13$ TeV of the $\rho$ parameter, the real to imaginary ratio of the nuclear elastic scattering amplitude at $t=0$, obtaining the following results: $\rho = 0.09 \pm 0.01$ and $\rho = 0.10 \pm 0.01$, depending on different physics assumptions and mathematical modelling. The unprecedented precision of the $\rho$ measurement, combined with the TOTEM total cross-section measurements in an energy range larger than 10 TeV (from 2.76 to 13 TeV), has implied the exclusion of all the models classified and published by COMPETE. The $\rho$ results obtained by TOTEM are compatible with the predictions, from alternative theoretical models both in the Regge-like framework and in the QCD framework, of a colourless 3-gluon bound state exchange in the $t$-channel of the proton-proton elastic scattering. On the contrary, if shown that the 3-gluon bound state $t$-channel exchange is not of importance for the description of elastic scattering, the $\rho$ value determined by TOTEM would represent a first evidence of a slowing down of the total cross-section growth at higher energies. The very low-$|t|$ reach allowed also to determine the absolute normalisation using the Coulomb amplitude for the first time at the LHC and obtain a new total proton-proton cross-section measurement $\sigma_{tot} = 110.3 \pm 3.5$ mb, completely independent from the previous TOTEM determination. Combining the two TOTEM results yields $\sigma_{tot} = 110.5 \pm 2.4$ mb.
Comment: 95 authors, 30 pages, 20 figures, 6 tables, submitted for publication. arXiv admin note: text overlap with arXiv:1610.00603
Comment: 95 authors, 30 pages, 20 figures, 6 tables, submitted for publication. arXiv admin note: text overlap with arXiv:1610.00603