 
FIZIKA B 7 (1998) 3, 139153
SO(10) MODEL OF GUT, PSEUDO  DIMENSION RULE AND THE DECAY K_{L}^{0}® m`e
PARTHASARATHI MUKHOPADHYAY
Department of Physics, Jadavpur University, Calcutta 700 032, India
Received 25 June 1998; Accepted 19 October 1998
The flavour nondiagonal decay K_{L}^{0} ® m`e, predicted by the SO(10) GUT model
to occur at the M_{C} scale, has not been seen in experiments. The limit on the
branching ratio is B(K_{L}^{0} ® m`e) < 3.3
×10^{11}. In the model, M_{C} turns out to be undetectably large. Its
version based on D parity, however, admits a much smaller value for M_{C} which is
detectable. For this reason, as argued in the literature, B(K_{L}^{0} ® m`e) can
be pushed to the level » 10^{12} in the context of
this version. This argument, as pointed out in this paper, ignores the bearing of the
pseudodimension rule on the decay concerned which is forbidden and as such suppresssed by
this rule. As a necessary outcome of this suppression, B (K_{L}^{0} ® m`e) is destined to lie far below the level of 10 ^{12} and, accordingly, the prospect of
experimental detection of this decay turns out to be much less than what is conventionally
expected. This paper, therefore, concludes that the nonobservation of this decay does not
disrepute the SO(10) GUT model with D parity.
PACS numbers: 12.10.Dm; 12.60.i
UDC 535.217, 539.21
Keywords: SO(10) model, grand unified theory (GUT), flavour nondiagonal decay,
pseudodimension rule
