Multiple exchanges in lepton pair production in high-energy heavy ion collisions
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As an archetype reaction for pQCD multigluon hard processes in collisions of ultrarelativistic nuclei, we analyze generic features of lepton pair production via multiphoton processes in peripheral heavy ion scattering. We report explicit results for collisions of two photons from one nucleus with two photons from the other nucleus, 2γ + 2γ → l+l−. The results suggest that the familiar eikonalization of Coulomb distortions breaks down for oppositely moving Coulomb centers. The breaking of eikonalization in QED suggests that multigluon pQCD processes cannot be described in terms of collective nuclear gluon distributions. We discuss a logarithmic enhancement of the contribution from the 2γ + 2γ → l+l− process to production of lepton pairs with large transverse momentum; similar enhancement is absent for the nγ + mγ → l+l− processes with m, n > 2. We comment on the general structure of multiphoton collisions and properties of higher-order terms that cannot be eikonalized.
KeywordsTransverse Momentum Pair Production Gluon Distribution Lepton Pair Multiple Exchange
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- 2.L. D. Landau and E. M. Lifshitz, Course of Theoretical Physics, Vol. 3: Quantum Mechanics: Non-Relativistic Theory, 4th ed. (Nauka, Moscow, 1989; Pergamon, New York, 1977).Google Scholar
- 4.S. R. Gevorkyan and S. S. Grigoryan, Phys. Rev. A 65, 022505 (2002).Google Scholar
- 5.N. N. Nikolaev, W. Schafer, B. G. Zakharov, and V. R. Zoller, Zh. Éksp. Teor. Fiz. 124, 491 (2003) [JETP 97, 441 (2003)].Google Scholar
- 6.N. N. Nikolaev, W. Schafer, B. G. Zakharov, and V. R. Zoller, hep-ph/0408054; Proc. of 12th Int. Workshop on Deep Inelastic Scattering (DIS2004), Štrbske Pleso, Slovakia.Google Scholar
- 9.U. Eichmann, J. Reinhardt, and W. Greiner, Phys. Rev. A 61, 062710 (2000).Google Scholar
- 11.R. N. Lee and A. I. Milstein, Phys. Rev. A 61, 032103 (2000).Google Scholar
- 12.E. Bartoš, S. R. Gevorkyan, N. N. Nikolaev, and E. A. Kuraev, Phys. Rev. A 66, 042720 (2002).Google Scholar
- 15.V. N. Gribov, L. N. Lipatov, and G. V. Frolov, Yad. Fiz. 12, 994 (1970) [Sov. J. Nucl. Phys. 12, 543 (1971)].Google Scholar
- 17.E. Bartoš, S. R. Gevorkyan, and E. A. Kuraev, Yad. Fiz. 67, 1945 (2004) [Phys. At. Nucl. 67, 1923 (2004)].Google Scholar