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Double-tag events in two-photon collisions at LEP

CollaborationWith : Achard, Pablo / Bourquin, Maurice / Braccini, Saverio / Chamizo Llatas, Maria / Deglon, Patrick / Delmeire, Evelyne / Echenard, Bertrand / Extermann, Pierre / Field, John / Kienzle, Maria-Novella / Malgeri, Luca / Natale, Sonia / Pohl, Martin
Published in Physics Letters. B. 2002, vol. 531, no. 1-2, p. 39-51
Abstract Double-tag events in two-photon collisions are studied using the L3 detector at LEP centre-of-mass energies from QY*Y* GeV to 209 GeV. The cross sections of the e+e−→e+e−hadrons and QY*Y* processes are measured as a function of the product of the photon virtualities, QY*Y*, of the two-photon mass, Wγγ, and of the variable Y=ln(W2γγ/Q2). The average photon virtuality is 〈Q21〉=〈Q22〉=16 GeV2. The results are in agreement with next-to-leading order calculations for the process √s=189 in the interval 2⩽Y⩽5. An excess is observed in the interval 5<Y⩽7, corresponding to Wγγ greater than 40 GeV. This may be interpreted as a contribution of resolved photon QCD processes or the onset of BFKL phenomena.
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L3 COLLABORATION. Double-tag events in two-photon collisions at LEP. In: Physics Letters. B, 2002, vol. 531, n° 1-2, p. 39-51. doi: 10.1016/S0370-2693(02)01340-0 https://archive-ouverte.unige.ch/unige:43259

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Deposited on : 2014-12-12

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