Measurement of the forward charged-particle pseudorapidity den- sity in pp collisions at √ s = 7TeV with the TOTEM experiment

The TOTEM experiment has measured the charged-particle pseudorapidity density dNch /dη in pp collisions at √ s =7 TeV for 5.3 < |η| < 6. 4i n 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 η region. The measurement refers to more than 99% of non-diffractive processes and to single and double diffractive processes with diffractive masses above ∼ 3. 4G eV/c 2 , corresponding to about 95% of the total inelastic cross-section. The dNch/dη has been found to decrease with |η|, from 3.84 ± 0.01(stat) ± 0.37(syst) at |η| =5 .375 to 2.38 ± 0.01(stat) ± 0.21(syst) at |η| =6 .375. Several MC generators have been compared to data; none of them has been found to fully describe the measurement. open access Copyright CERN for the benefit of the TOTEM Collaboration. Published by the EPLA under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.