At the LHC energy of √s = 7TeV, under various beam and background conditions, luminosities, and Roman Pot positions, TOTEM has measured the differential cross-section for proton-proton elastic scattering as a function of the four-momentum transfer squared t. The results of the different analyses are in excellent agreement demonstrating no sizeable dependence on the beam conditions. Due to the very close approach of the Roman Pot detectors to the beam enter (≈5σbeam) in a dedicated run with β*= 90m, |t|-values down to 5·10-3 GeV-2 were reached. The exponential slope of the differential elastic cross-section in this newly explored |t|-region remained unchanged and thus an exponential fit with only one constant B = (19.9±0.3) GeV-2 over the large |t|-range from 0.005 to 0.2GeV2 describes the differential distribution well. The high precision of the measurement and the large fit range lead to an error on the slope parameter B which is remarkably small compared to previous experiments. It allows a precise extrapolation over the non-visible cross-section (only 9%) to t = 0. With the luminosity from CMS, the elastic crosssection was determined to be (25.4±1.1)mb, and using in addition the optical theorem, the total pp cross-section was derived to be (98.6±2.2)mb. For model comparisons the t-distributions are tabulated including the large |t|-range of the previous measurement (TOTEM Collaboration (Antchev G. et al.), EPL, 95 (2011) 41001).
Measurement of proton-proton elastic scattering and total cross-section at √s = 7 TeV
BOZZO, MARCO;FERRO, FABRIZIO;LO VETERE, MAURIZIO;ROBUTTI, ENRICO;SANTRONI, ALBERTO;
2013-01-01
Abstract
At the LHC energy of √s = 7TeV, under various beam and background conditions, luminosities, and Roman Pot positions, TOTEM has measured the differential cross-section for proton-proton elastic scattering as a function of the four-momentum transfer squared t. The results of the different analyses are in excellent agreement demonstrating no sizeable dependence on the beam conditions. Due to the very close approach of the Roman Pot detectors to the beam enter (≈5σbeam) in a dedicated run with β*= 90m, |t|-values down to 5·10-3 GeV-2 were reached. The exponential slope of the differential elastic cross-section in this newly explored |t|-region remained unchanged and thus an exponential fit with only one constant B = (19.9±0.3) GeV-2 over the large |t|-range from 0.005 to 0.2GeV2 describes the differential distribution well. The high precision of the measurement and the large fit range lead to an error on the slope parameter B which is remarkably small compared to previous experiments. It allows a precise extrapolation over the non-visible cross-section (only 9%) to t = 0. With the luminosity from CMS, the elastic crosssection was determined to be (25.4±1.1)mb, and using in addition the optical theorem, the total pp cross-section was derived to be (98.6±2.2)mb. For model comparisons the t-distributions are tabulated including the large |t|-range of the previous measurement (TOTEM Collaboration (Antchev G. et al.), EPL, 95 (2011) 41001).
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