Hoda Hesari, Mojtaba Mohammadi Najafabadi
In this paper, we study the sensitivity of the fraction of $t\bar{t}$ events arising from gluon-gluon fusion to the chromoelectric and chromomagnetic dipole moments (CEDM and CMDM) as well as the $t\bar{t}$ cross sections at the LHC and Tevatron, and the recently measured charged asymmetry at the LHC. We find that at the Tevatron and the LHC, non-zero values of CMDM could suppress the $t\bar{t}$ production rate. It is shown that the ratio of $\sigma(gg\rightarrow t\bar{t})/\sigma(p\bar{p}\rightarrow t\bar{t})$ at the Tevatron is more sensitive to CEDM and CMDM than the LHC case. The presence of CEDM always increases the contribution of gluon-gluon fusion process in top pair rate at the Tevatron and LHC. Except for a small range of CMDM, the presence of CEDM and CMDM can increase the fraction of gluon-gluon fusion at the Tevatron and LHC. The measured ratio of $\sigma(gg\rightarrow t\bar{t})/\sigma(p\bar{p}\rightarrow t\bar{t})$ at the Tevatron is used to derive bounds on the chromoelectric and chromomagnetic dipole moments as well as the cross sections at the LHC and Tevatron, and the measured charged asymmetry at the LHC.
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http://arxiv.org/abs/1207.0339
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