Browsing by Author "Geng, C. Q."

Now showing 1 - 4 of 4

Charmful two-body antitriplet b-baryon decays
(2015-12-08)
Hsiao, Y. K.
;
Lin, P. Y.
;
Lih, C. C.
;
Geng, C. Q.
;
電子物理學系
We study the charmful decays of the two-body B-b -> BnMc decays, where B-b represents the antitriplet of (Lambda(b), Xi(0)(b), Xi(-)(b)), B-n stands for the baryon octet, and M-c denotes the charmed meson of D-(s)((*)), eta(c) and J/psi. Explicitly, we predict that B(Lambda(b) -> D(s)(-)p) = (1.8 +/- 0.3) x 10(-5), which is within the measured upper bound of B(Lambda(b) -> D(s)(-)p) < 4.8(5.3) x 10(-4) at 90% (95%) C.L., and reproduce B(Lambda(b) -> J/psi Lambda) = (3.3 +/- 2.0) x 10(-4) and B(Xi(-)(b) -> J/psi Xi(-)) = (5.1 +/- 3.2) x 10(-4) in agreement with the data. Moreover, we find that B(Lambda(b) -> Lambda eta(c)) = (1.5 +/- 0.9) x 10(-4), B(Xi(-)(b) -> Xi(-)eta(c)) = (2.4 +/- 1.5) x 10(-4) and B(Xi(0)(b) -> Xi(0)eta(c), Xi(0)J/psi) = (2.3 +/- 1.4, 4.9 +/- 3.0) x 10(-4), which are accessible to the experiments at the LHCb.
Cosmological birefringence due to CPT-even Chern-Simons-like term with Kalb-Ramond and scalar fields
(2015-05-05)
Ho, Shih-Hao
;
Kao, W. F.
;
Bamba, Kazuharu
;
Geng, C. Q.
;
物理研究所
We study the CPT-even dimension-six Chern-Simons-like term by including dynamical Kalb-Ramond and scalar fields to examine the cosmological birefringence. We show that the combined effect of a neutrino current and a Kalb-Ramond field could induce a sizable rotation polarization angle in the cosmic microwave background radiation polarization.
Fragmentation fractions of two-body b-baryon decays
(2015-12-17)
Hsiao, Y. K.
;
Lin, P. Y.
;
Luo, L. W.
;
Geng, C. Q.
;
電子物理學系
We study the fragmentation fractions (f(Bb)) of the b-quark to b-baryons (B-b). By the assumption of f(Lambda b)/(f(u) + f(d)) = 0.25 +/- 0.15 in accordance with the measurements by LEP, CDF and LHCb Collaborations, we estimate that f(Lambda b)= 0.175 +/- 0.106 and f(Xi b)(-),0 = 0.019 +/- 0.013. From these fragmentation fractions, we derive B(Lambda(b) -> J/psi Lambda) =(3.3 +/- 2.1) x10(-4), B(Xi(-)(b) -> J/psi Xi(-)) = (5.3 +/- 3.9) x10(-4) and B(Omega(-)(b) -> J/psi Omega(-)) > 1.9 x10(-5). The predictions of B(Lambda(b) -> J/psi Lambda) and B(Xi(-)(b) -> J/psi Xi(-)) clearly enable us to test the theoretical models, such as the QCD factorization approach in the b-baryon decays. (C) 2015 The Authors. Published by Elsevier B.V.
Large-scale magnetic fields from inflation due to a CPT-even Chern-Simons-like term with Kalb-Ramond and scalar fields
(2012-04-01)
Bamba, Kazuharu
;
Geng, C. Q.
;
Ho, S. H.
;
Kao, W. F.
;
物理研究所
We investigate the generation of large-scale magnetic fields due to the breaking of the conformal invariance in the electromagnetic field through the CPT-even dimension-six Chern-Simons-like effective interaction with a fermion current by taking account of the dynamical Kalb-Ramond and scalar fields in inflationary cosmology. It is explicitly demonstrated that magnetic fields on 1 Mpc scale with the field strength of similar to 10(-9) G at the present time can be induced.