Abstract
We revise the μ+μ− and \(q\bar q\) annihilation mechanisms of dilepton production during relativistic nuclear collisions. We focus on the modifications caused by the specific features of in-medium pion and quark states rather than by medium modification of the ρ-meson spectral density. The main ingreditent emerging in our approach is a form-factor of the multi-pion (multi-quark) system. Replacing the usual delta-function the form-factor plays the role of distribution which, in some sense, “connects” the total 4-momenta of the annihilating and outgoing particles. The difference between the c.m.s. velocities attributed to annihilating and outgoing particles is a particular consequence of this replacement and results in the appearance of a new factor in the formula for the lepton pair production rate. We obtained that the form-factor of the multi-pion (multi-quark) system causes broadening of the rate which is most pronounced for small invariant masses, in particular, we obtain a growth of the rate for the invariant masses below two masses of the annihilating particles.
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References
G. Agakichiev et al., Phys. Rev. Lett. 75 (1995) 1272.
G. Agakichiev et al., Phys. Lett. B422 (1998) 405.
C. Gale and K.L. Haglin, hep-ph/0306098.
W. Cassing and E.L. Bratkovskaya, Phys. Rept. 308 (1999) 65.
R. Rapp and J. Wambach, Adv. Nucl. Phys. 25 (2000) 1.
V. Koch and C. Song, Phys. Rev C 54 (1996) 1903.
K. Haglin, Phys. Rev. C 53 (1996) R2606.
G. Agakichiev et al., Eur. Phys. J. C 41 (2005) 475 [nucl-ex/0506002].
D. Anchishkin, V. Khryapa and V. Ruuskanen, hep-ph/0210346.
D. Anchishkin, V. Khryapa, R. Naryshkin and V. Ruuskanen, Ukrainian J. Phys. 49 (2004) 1039.
H. van Hees, J. Knoll, Nucl. Phys. A683 (2000) 369 [hep-ph/0007070].
D. Anchishkin and R. Naryshkin, Mod. Phys. Lett. A20 (2005) 2047 [nucl-th/0407042].
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Anchishkin, D. Annihilation mechanisms of e+e− and μ+μ− production in relativistic nuclear collisions. Acta Phys. Hung. A 27, 403–411 (2006). https://doi.org/10.1556/APH.27.2006.4.3
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DOI: https://doi.org/10.1556/APH.27.2006.4.3