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Determination of proton parton densities using early LHC data and of contrains on new physics beyond the Standard Model


The Large Hadron Collider (LHC) at CERN will collide protons at a centre-of-mass energy of 14 TeV. The combination of its high collision rate and centre-of-mass energy will make it possible to probe new interactions at very short distances. Such interactions might be revealed in the production of cross-sections of particles at very high transverse momentum as a deviation from the Standard Model. However, the sensitivity to new physics depends on experimental uncertainties in the measurements and on theoretical uncertainties in the Standard Model predictions. For instance, one could use single inclusive jet and lepton pair production cross-sections at low transverse momentum to constrain the parton density functions uncertainties at high transverse momentum. One of the goals of the project is to investigate by what kind of measurements or combination of measurements present theoretical an experimental uncertainties could be reduced. A particular difficulty at the LHC is the uncertainty on the luminosity of the data set used for the cross section measurement. Typically the main experimental uncertainties are due to the limited knowledge of the absolute energy scale (ES). In the case of an electron relevant for the measurement of lepton pair production, the ES can be deduced from reference reactions. In the case of jet cross section the situation is more difficult. In addition to the knowledge of the absolute ES, uncertainties arise from the non-perturbative hadronisation corrections necessary to connect the measurements to the calculation and from underlying events. The high precision measurements of lepton pairs produced at LHC will serve as a tool for understanding and calibrating the detector response. Moreover, one can extract the parton density information from the lepton pair production data and use it for the new physics effects searches.

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Esplanade Des Particules 1 Parcelle 11482 De Meyrin Batiment Cadastral 1046
1211 Geneva 23
Activity type
Research Organisations
EU contribution
€ 189 163,26
Administrative Contact
Seamus Hegarty (Mr.)