• A K Giri

Articles written in Pramana – Journal of Physics

• Effect of heavy quark symmetry on the mass difference ofB-system in minimal left right symmetric model

An estimation of the mass difference of$$B_d^0 - \bar B_d^0$$ system with heavy quark symmetry formalism is presented. The effective Hamiltonian describing the transition$$\bar hd \leftrightarrow h\bar d$$ (whereh=b forBd0-system) is considered in a manifest left right symmetric (MLRS) model along with contribution from neutral Higgs boson. We use the spin and flavor symmetry for heavy quarks to obtain the transition matrix element 〈Bd0|ℋeff(x)|$$\bar B_d^0$$d0〉 in terms of Isgur-Wise function. Assuming thatBd0 and$$\bar B_d^0$$ states are at rest, we find that Isgur-Wise function turns out to be unity. However using the experimental values of ΔMK and$$\Delta M_{B_4 }$$ as input, we find thatMR=835 GeV andMH⩾2·9 TeV.

• Ratios ofB andD meson decay constants with heavy quark symmetry

SU(3) flavor symmetry allows the decay constantsfD1 andfD2 as well asfB1 andfB1 to be equal. But due toSU(3) flavor symmetry breaking the ratiosfB1/fB2 andfD1/fD2 are deviated from unity. We have estimated these ratios in the heavy quark effective theory and obtainedfB1/fB2=0.93,fD1/fD2=0.94 and the double ratio (fB1/fB2)/(fD1/fD2)=0.99.

• Radiative decays of heavy mesons with heavy quark symmetry

The radiative decays of heavy mesons are considered in heavy quark symmetry formalism. Introducing the interpolating fields for the heavy mesons we obtain the transition matrix element and the corresponding decay widths in the heavy quark symmetry limits. The Isgur-Wise function present in the expression is determined by ISGW quark model. The results obtained agree reasonably well with other estimations.

• Ratios ofB andD meson decay constants with heavy quark symmetry

• Radiative decays of heavy baryons with heavy quark symmetry

The decay widths for the radiative decays of heavy baryons are calculated in the heavy quark effective theory. Introducing the interpolating fields for heavy baryons we obtain the transition matrix elements and the corresponding decay widths. Considering theSU(6) flavor-spin wave functions for heavy baryons, the coupling constants are calculated in the nonrelativistic quark model. Since the masses of the heavy baryons are not available, we have taken the predicted bag model masses. We find our results are quite different from that of the heavy quark bag model calculations.

• Two body non-leptonic decaysB with heavy quark and chiral symmetry

We have analysed the two body non-leptonic charmed-meson decays of heavyB meson based on the factorization assumption. The transition matrix elements and the corresponding decay widths are calculated in the heavy quark and chiral symmetry limit and the Isgur-Wise function present in the expression is determined by the wave function model of Aliet al. The results obtained are quite interesting and agree reasonably well with the experimental data.

• Some two body non-leptonicB decays and estimation offD in the heavy quark effective theory

We have studied some of the two body nonleptonic decays ofB meson in the context of heavy quark effective theory using factorization hypothesis. Treatinga1 as a free parameter, we have obtained its value asa1=0.822±0.045, by correlating the experimental and predicted branching ratio for$$\bar B^0 \to D^ + \pi ^ -$$ process. With this value ofa1 the branching ratios obtained for other decay channels are in good agreement with the experiment. The decay constant ofD meson is extracted to be 280.82 MeV. Heavy quark spin symmetry has also been tested.

• Two body non-leptonic Λb decays in the largeNc limit

The two body non-leptonic Λb decays are analysed in the HQET with factorization approximation and largeNc limit. In this limit, Λb and Λc baryons can be treated as the bound states of chiral soliton and heavy meson, and consequently the Isgur-Wise function comes out in a straight forward manner. The results obtained remain well below their previously predicted upper limit.

• Ratio of the color suppressed decays Λb→ΛJ/ψ andB0KJ/ψ

Based on the factorization approximation, we have estimated the ratio of the branching fractions for the color suppressed nonleptonic decays Λb→ΛJ/ψ andB0KJ/ψ. Treating thes-quark as heavy, we have used the HQET to calculate the hadronic matrix elements. The mesonic Isgur-Wise function is calculated in the quark model whereas for the baryonic IW function we have employed the bound state soliton picture. The results obtained agree very well with the recent CDF experimental data.

• Weak radiative decay Λb→Λγ in the heavy quark effective theory

The weak radiative decay Λb→Λγ is studied in the heavy quark effective theory treatings-quark as heavy. This rare decay is induced by the short distance electromagnetic penguins. Including corrections of the order of (1/mQ), we obtain the transition matrix element and the corresponding decay width. The Isgur-Wise function is evaluated in the largeNc limit and the branching ratio obtained is 1.48×10−5.

• # Pramana – Journal of Physics

Volume 94, 2019
All articles
Continuous Article Publishing mode

• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019