2018 Impact factor 4.843
Particles and Fields
Eur. Phys. J. C 11, 485-493
DOI 10.1007/s100529900089

## Longitudinal quark polarization in and chromoelectric and chromomagnetic dipole couplings of the top quark

S.D. Rindani1 - M.M. Tung2

1 Theory Group, Physical Research Laboratory, Navrangpura, Ahmedabad 380 009, India
2 Institute for Theoretical Physics, State University of New York, Stony Brook, NY 11794-3840, USA

Received: 3 September 1998 / Revised version: 15 February 1999 / Published online: 22 October 1999

Abstract
The effect of anomalous chromomagnetic () and chromoelectric couplings (d) of the gluon to the top quark is considered in , with unpolarized and longitudinally polarized electron beams. The total cross section, as well as t and polarizations, are calculated to order in the presence of the anomalous couplings. One of the two linear combinations of t and polarizations is CP even, while the other is CP odd. The limits that could be obtained at a typical future linear collider with an integrated luminosity of 50 fb-1 and a total c.m. energy of 500 GeV on the most sensitive CP-even combination of anomalous couplings, are estimated as , for , and , for . There is an improvement by roughly a factor of 2 at 1000 GeV. On the other hand, from the CP-odd combination, we derive the possible complementary bounds as , for , and , for , for a c.m. energy of 500 GeV. The corresponding limit for 1000 GeV is almost an order of magnitude better for , though somewhat worse for . Results for the c.m. energies 500 GeV and 1000 GeV, if combined, would yield independent limits on the two CP-violating parameters of and .