FIZIKA B 11 (2002)  2, 103-114

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STUDY OF RADIATIVE B-DECAY CONSIDERING TWO-HIGGS-DOUBLET MODELS AND THE FOURTH GENERATION IN THE QUARK SECTOR

HARAPRASAD ROY, SURATH KUMAR BISWAS and VINOD P. GAUTAM

Theoretical Physics Department, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700032, India
E-mail address: tpdpb@mahendra.iacs.res.in

Received 15 December 2000 ; revised manuscript received 8 June 2002
Accepted 6 September 2002        Online 7 February 2003

Considering the nonstandard indirect effect of Yukawa couplings of the Higgs doublet to the quarks, we examine strong-interaction effects in weak radiative B-meson decay. The virtual effects of the Model I and Model II in the penguin-type diagram on the b sg decay have been tested considering the possibility of the fourth generation in quark sector, with corrections up to the leading QCD logarithms, using evolution of the fourth-generation CKM matrix, with CP violation phase equal to zero. Range of the masses of the fourth-generation down-type quark b and up-type quark t have been taken with due consideration of the constraint imposed by the present experimental value of the r parameter, keeping in view the mass difference of the fourth-generation quark doublet. As a by-product, it is observed that the CLEO bound clearly sets the lower bound on the Higgs boson mass at 220 GeV, which is above the top quark mass.

PACS numbers: 12.60.-i
UDC 539.126

Keywords: weak radiative B-meson decay, fourth generation, Higgs boson mass

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