Measurement of the total cross section from elastic scattering in pp collisions at √s=7 TeV with the ATLAS detector

A measurement of the total pp cross section at the LHC at √ s = 7 TeV is presented. In a special run with high-β⋆ beam optics, an integrated luminosity of 80 μb−1 was accumulated in order to measure the differential elastic cross section as a function of the Mandelstam momentum transfer variable t . The measurement is performed with the ALFA sub-detector of ATLAS. Using a fit to the differential elastic cross section in the |t | range from 0.01 GeV2 to 0.1 GeV2 to extrapolate to |t | → 0, the total cross section, σtot(pp→X), is measured via the optical theorem to be: σtot(pp→X)= 95.35± 0.38 (stat.)± 1.25 (exp.)± 0.37 (extr.) mb, where the first error is statistical, the second accounts for all experimental systematic uncertainties and the last is related to uncertainties in the extrapolation to |t | → 0. In addition, the slope of the elastic cross section at small |t | is determined to be B = 19.73 ± 0.14 (stat.) ± 0.26 (syst.) GeV−2.  2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/3.0/). Funded by SCOAP3. ⋆ E-mail address: [email protected]. http://dx.doi.org/10.1016/j.nuclphysb.2014.10.019 0550-3213/ 2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/3.0/). Funded by SCOAP3 . ATLAS Collaboration / Nuclear Physics B 889 (2014) 486–548 487