## Abstract

A measurement of the total pp cross section at the LHC at √s = 8 TeV is presented. An integrated luminosity of 500 µb

−1 was accumulated in a special run with high-β? beam optics

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 0.014 GeV2 to 0.1 GeV2 to extrapolate t → 0, the total cross section, σtot(pp → X), is measured via the optical theorem to be

σtot(pp → X) = 96.07 ± 0.18 (stat.) ± 0.85 (exp.) ± 0.31 (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 t → 0. In addition, the

slope of the exponential function describing the elastic cross section at small t is determined to be B = 19.74 ± 0.05 (stat.) ± 0.23 (syst.) GeV−2.

−1 was accumulated in a special run with high-β? beam optics

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 0.014 GeV2 to 0.1 GeV2 to extrapolate t → 0, the total cross section, σtot(pp → X), is measured via the optical theorem to be

σtot(pp → X) = 96.07 ± 0.18 (stat.) ± 0.85 (exp.) ± 0.31 (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 t → 0. In addition, the

slope of the exponential function describing the elastic cross section at small t is determined to be B = 19.74 ± 0.05 (stat.) ± 0.23 (syst.) GeV−2.

Original language | English |
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Journal | Physics Letters B |

Early online date | 16 Aug 2016 |

DOIs | |

Publication status | Published - 10 Oct 2016 |

### Bibliographical note

17 pages plus author list + cover page (35 pages total), 4 figures, 2 tables, submitted to PLB. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2015-22/## Keywords

- hep-ex