1205.4105 (G. Antchev et al.)

Measurement of the forward charged particle pseudorapidity density in pp
collisions at sqrt{s} = 7 TeV with the TOTEM experiment    [PDF]

G. Antchev, P. Aspell, I. Atanassov, V. Avati, J. Baechler, V. Berardi, M. Berretti, E. Bossini, M. Bozzo, P. Brogi, E. Brücken, A. Buzzo, F. S. Cafagna, M. Calicchio, M. G. Catanesi, C. Covault, M. Csanád, T. Csörgő, M. Deile, K Eggert, V. Eremin, R. Ferretti, F. Ferro, A. Fiergolski, F. Garcia, S. Giani, V. Greco, L. Grzanka, J. Heino, T. Hilden, M. R. Intonti, J. Kašpar, J. Kopal, V. Kundrát, K. Kurvinen, S. Lami, G. Latino, R. Lauhakangas, T. Leszko, E. Lippmaa, M. Lokajíček, M. Lo Vetere, F. Lucas Rodríguez, M. Macrí, L. Magaletti, T. Mäki, A. Mercadante, N. Minafra, S. Minutoli, F. Nemes, H. Niewiadomski, E. Oliveri, F. Oljemark, R. Orava, M. Oriunno, K. Österberg, P. Palazzi, J. Procházka, M. Quinto, E. Radermacher, E. Radicioni, F. Ravotti, E. Robutti, L. Ropelewski, G. Ruggiero, H. Saarikko, A. Santroni, A. Scribano, W. Snoeys, J. Sziklai, C. Taylor, N. Turini, V. Vacek, M. Vitek, J. Welti, J. Whitmore

The TOTEM experiment has measured the charged particle pseudorapidity density dN_{ch}/deta in pp collisions at sqrt{s} = 7 TeV for 5.3<|eta|<6.4 in events with at least one charged particle with transverse momentum above 40 MeV/c in this pseudorapidity range. This extends the analogous measurement performed by the other LHC experiments to the previously unexplored forward eta region. The measurement refers to more than 99% of non-diffractive processes and to single and double diffractive processes with diffractive masses above ~3.4 GeV/c^2, corresponding to about 95% of the total inelastic cross-section. The dN_{ch}/deta has been found to decrease with |eta|, from 3.84 pm 0.01(stat) pm 0.37(syst) at |eta| = 5.375 to 2.38 pm 0.01(stat) pm 0.21(syst) at |eta| = 6.375. Several MC generators have been compared to data; none of them has been found to fully describe the measurement.

View original: http://arxiv.org/abs/1205.4105