학술논문
First determination of the $${\rho }$$ ρ parameter at $${\sqrt{s} = 13}$$ s=13 TeV: probing the existence of a colourless C-odd three-gluon compound state
Document Type
article
Author
G. Antchev; P. Aspell; I. Atanassov; V. Avati; J. Baechler; C. Baldenegro Barrera; V. Berardi; M. Berretti; E. Bossini; U. Bottigli; M. Bozzo; R. Bruce; H. Burkhardt; F. S. Cafagna; M. G. Catanesi; M. Csanád; T. Csörgő; M. Deile; F. De Leonardis; A. D’Orazio; M. Doubek; D. Druzhkin; K. Eggert; V. Eremin; F. Ferro; A. Fiergolski; F. Garcia; H. Garcia Morales; V. Georgiev; S. Giani; L. Grzanka; J. Hammerbauer; J. Heino; P. Helander; T. Isidori; V. Ivanchenko; M. Janda; A. Karev; J. Kašpar; J. Kopal; V. Kundrát; S. Lami; G. Latino; R. Lauhakangas; R. Linhart; C. Lindsey; M. V. Lokajíček; L. Losurdo; M. Lo Vetere; F. Lucas Rodríguez; M. Macrí; M. Malawski; A. Mereghetti; N. Minafra; S. Minutoli; D. Mirarchi; T. Naaranoja; F. Nemes; H. Niewiadomski; T. Novák; E. Oliveri; F. Oljemark; M. Oriunno; K. Österberg; P. Palazzi; V. Passaro; Z. Peroutka; J. Procházka; M. Quinto; E. Radermacher; E. Radicioni; F. Ravotti; S. Redaelli; E. Robutti; C. Royon; G. Ruggiero; H. Saarikko; B. Salvachua; A. Scribano; J. Siroky; J. Smajek; W. Snoeys; R. Stefanovitch; J. Sziklai; C. Taylor; E. Tcherniaev; N. Turini; V. Vacek; G. Valentino; J. Welti; J. Wenninger; J. Williams; P. Wyszkowski; J. Zich; K. Zielinski
Source
European Physical Journal C: Particles and Fields, Vol 79, Iss 9, Pp 1-26 (2019)
Subject
Language
English
ISSN
1434-6044
1434-6052
1434-6052
Abstract
Abstract The TOTEM experiment at the LHC has performed the first measurement at $$\sqrt{s} = 13\,\mathrm{TeV}$$ s=13TeV of the $$\rho $$ ρ parameter, the real to imaginary ratio of the nuclear elastic scattering amplitude at $$t=0$$ t=0 , obtaining the following results: $$\rho = 0.09 \pm 0.01$$ ρ=0.09±0.01 and $$\rho = 0.10 \pm 0.01$$ ρ=0.10±0.01 , depending on different physics assumptions and mathematical modelling. The unprecedented precision of the $$\rho $$ ρ measurement, combined with the TOTEM total cross-section measurements in an energy range larger than $$10\,\mathrm{TeV}$$ 10TeV (from 2.76 to $$13\,\mathrm{TeV}$$ 13TeV ), has implied the exclusion of all the models classified and published by COMPETE. The $$\rho $$ ρ results obtained by TOTEM are compatible with the predictions, from other theoretical models both in the Regge-like framework and in the QCD framework, of a crossing-odd colourless 3-gluon compound state exchange in the t-channel of the proton–proton elastic scattering. On the contrary, if shown that the crossing-odd 3-gluon compound state t-channel exchange is not of importance for the description of elastic scattering, the $$\rho $$ ρ 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 $$\sigma _{\mathrm{tot}} = (110.3 \pm 3.5)\,\mathrm{mb}$$ σtot=(110.3±3.5)mb , completely independent from the previous TOTEM determination. Combining the two TOTEM results yields $$\sigma _{\mathrm{tot}} = (110.5 \pm 2.4)\,\mathrm{mb}$$ σtot=(110.5±2.4)mb .