EFFECT OF A 4TH FERMION GENERATION ON THE MT UPPER BOUND

被引：59

作者：

BERTOLINI, S ^{[1
]}

SIRLIN, A ^{[1
]}

机构：

[1] COLUMBIA UNIV,DEPT PHYS,NEW YORK,NY 10027

来源：

PHYSICS LETTERS B | 1991年 / 257卷 / 1-2期

基金：

美国国家科学基金会;

关键词：

D O I：

10.1016/0370-2693(91)90878-T

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We discuss the possibility that the upper bound (m(t))sup on the top mass may be relaxed due to the presence of a fourth generation of fermions. If the additional neutrino is a Dirac particle we find that, for arbitrary values of the masses of the extra quarks and leptons and of their mixings with the fermions of the third generation, (m(t))sup can be increased by at most 7 GeV. We then consider the scenario in which, aside from the Dirac mass, the right-handed neutrino of the fourth generation is endowed with a Majorana mass of O(G-mu-1/2). In this case we find a qualitatively different result: the contributions to DELTA-r (DELTA-rho) are not mathematically bounded from above (below), so that there can be significant contributions of sign opposite to the top effect. Restricting the Dirac mass entry to less-than-or-equal-to 300 GeV, we find that (m(t))sup can be increased by at most 31 GeV.

引用

页码：179 / 186

页数：8

共 19 条

[11] A NATURALLY HEAVY 4TH GENERATION NEUTRINO [J].