E ects of Screening on Quark - Antiquark Cross Sections in Quark - Gluon Plasma

Lowest-order cross sections for q q production and annihilation can be approximately corrected for higher-order QCD e ects by using a corrective Kfactor. For energies where quark masses cannot be ignored, the K-factor is dominated by the wave function distortion arising from the initialor nalstate interaction between the quark and the antiquark. We evaluate this Kfactor for q q production and annihilation in a quark-gluon plasma by taking into account the e ects of Debye screening through a color-Yukawa potential. We present the corrective K-factor as a function of dimensionless parameters which may nd applications in other systems involving attractive or repulsive Yukawa interactions. Prominent peaks of the K-factor occur for an attractive qq color-Yukawa interaction with Debye screening lengths of 0.835 and 3.23 times the Bohr radius, corresponding to two lowest s-wave q q bound states moving into the continuum to become q q resonances as the Debye screening length decreases. These resonances, especially the c c and the b b resonances, may be utilized to search for the quark-gluon plasma by studying the sys-