Study of B, $$B_s$$ mesons using heavy quark effective theory

Proceedings of XVII International Conference on Hadron Spectroscopy and Structure — PoS(Hadron2017), 2018

In the last decade, charmed and bottom meson spectroscopy have seen great success in experimental sector. Experiments like LHCb, Babar etc are providing many new states which are being added to their spectroscopy. Newly predicted states like B(5970), D 2 (3000), D * (3000), B(5840) and many more still need to be assigned their proper place in the spectroscopy. So we studied the decay constant and the coupling constants of these states using the heavy quark effective theory as our model. We analyzed the two-body strong decays of the above states to their ground state mesons with light pseudo-scalar mesons (π, η, K). We also obtained the ratios among their strong decays, which can be confronted to the experimental data for the verification of their J P states. In addition to this, we also study the strong decays of their spin and strange partners, which are still experimentally not observed, and may be useful for future experiments in searching for these heavy-light mesons.

XXII DAE High Energy Physics Symposium, 2018

In this paper, Heavy Quark Effective Field Theory (HQET) is motivated and discussed. The lagrangian in this effective theory is derived to order 1/mQ and the 1-loop quantum corrections are added. Using this lagrangian, the mass of a meson is found in terms of 3 parameters, Λ ̄,λ1 and λ2. Mass splittings are then calculated between meson states when two of these parameters are the same. The decay rate of processes with the general form B ̄ → D⋆lν ̄ is derived both using the full theory and the HQET. It is shown that the form factors are given by one function, the Isgur-Wise function ξ(w).

International Journal of Modern Physics A, 2005

Recent progress in the theory of B-meson decays is reviewed with emphasis on the aspects related to the B-factory data.

arXiv: High Energy Physics - Phenomenology, 2016

Inspired from the experimental information coming from LHC [2,3] and Babar [4] for radially higher excited charmed mesons, we predict the masses and decays of the n=2 S-wave and P- wave bottom mesons using the effective lagrangian approach. Using heavy quark effective theory approach, non-perturbative parameters (?, ?1 and ?2) are fitted using the available experimental and theoretical informations on charm masses. Using heavy quark symmetry and the values of these fitted parameters, the masses of radially excited even and odd parity bottom mesons with and without strangness are predicted. These predicted masses led in constraining the decay widths of these 12 states, and also shed light on the unknown values of the higher hadronic coupling constants eeg 2 SH and eeg 2 TH. Studying the properties like masses, decays of 2S and 2P states and some hadronic couplings would help forthcoming experiments to look into these states in future.

Nuclear Physics B, 1984

We find the domain of the values of mr, "r B and R (the top quark mass, the B-meson lifetime and F(b-* u)/F(b-, c) respectively) for which the standard six-quark model is consistent with the observed CP violation in the kaon system and with the recent experimental results for B-meson decays. The mixing angles 02 , 03 , the phase 6 and the ratio e'/e are calculated as functions of m t, % and R. The sensitivity of the analysis to the variation of the "bag" parameter B and the band c-quark masses is investigated. Two types of calculations are presented: one wbSch takes into account the KL-K s mass difference and the other one which ignores it. We discuss the implications 1 of a possible discovery of a top quark with m t below 30 GeV and we point out that for B ~< ~ and m t ~ 0(25 GeV) a simultaneous consistency of the standard model with the data for %, R, e and e'/E cannot be achieved. Furthermore for B~< ~ and m t ~< 35 GeV we find e'/e/> 0.01. No interesting upper bound on m t follows from KL ~ ~g.

Physical Review D, 1998

In this paper we present a detailed formulation for a recently proposed effective field theory to describe the nonperturbative QCD dynamics of heavy mesons. This effective theory incorporates with heavy quark symmetry (HQS) and the heavy quark effective theory (HQET). Heavy mesons in this theory are constructed as composite particles of a heavy quark bounded with the light degrees of freedom. The heavy meson properties in the heavy quark limit and the 1/m Q corrections can then be explicitly evaluated from this effective theory. All the basic parameters of the HQET, namely, the heavy quark mass m Q , the heavy meson residual mass Λ, and the HQS breaking mass parameters λ 1 and λ 2 , are consistently determined. λ 1 is found to be small due to a large cancellation between the heavy quark kinetic energy and the chromo-electric interaction between the heavy quark and light degrees of freedom. We also evaluate the Isgur-Wise function, the decay constant, and the axial-vector coupling constant of heavy mesons.

We calculate the B-meson decay constants fB, fB s , and their ratio in unquenched lattice QCD using domain-wall light quarks and relativistic b-quarks. We use gauge-field ensembles generated by the RBC and UKQCD collaborations using the domain-wall fermion action and Iwasaki gauge action with three flavors of light dynamical quarks. We analyze data at two lattice spacings of a ≈ 0.11, 0.086 fm with unitary pion masses as light as Mπ ≈ 290 MeV; this enables us to control the extrapolation to the physical light-quark masses and continuum. For the b-quarks we use the anisotropic clover action with the relativistic heavy-quark interpretation, such that discretization errors from the heavy-quark action are of the same size as from the light-quark sector. We renormalize the lattice heavy-light axial-vector current using a mostly nonperturbative method in which we compute the bulk of the matching factor nonperturbatively, with a small correction, that is close to unity, in lattice perturbation theory. We also improve the lattice heavy-light current through O(αsa). We extrapolate our results to the physical light-quark masses and continuum using SU(2) heavy-meson chiral perturbation theory, and provide a complete systematic error budget. We obtain f B 0 = 199.5(12.6) MeV, f B + = 195.6(14.9) MeV, fB s = 235.4(12.2) MeV, fB s /f B 0 = 1.197(50), and fB s /f B + = 1.223(71), where the errors are statistical and total systematic added in quadrature. These results are in good agreement with other published results and provide an important independent cross check of other three-flavor determinations of B-meson decay constants using staggered light quarks.

Physics Letters B, 2014

We report our final estimate of the b-quark mass from N f = 2 lattice QCD simulations using Heavy Quark Effective Theory non-perturbatively matched to QCD at O(1/m h). Treating systematic and statistical errors in a conservative manner, we obtain m MS b (2 GeV) = 4.88(15) GeV after an extrapolation to the physical point.

Communications in Theoretical Physics, 2019

We employ the variational method to study the properties such as masses,decay constants,Oscillation frequency and Branching ratios of leptonic decays of heavy flavour mesons with linear cum coulomb Cornell potential. Gaussian function, Coulomb wave function and Airy function are taken as the trial wave-function of variational method in this study. Our analysis suggests that Gaussian trial wave-function provides results which are in close proximity with the experimental results. We also make a comparison with the results from QCD Sum rules and lattice QCD ,as well as with recent PDG data .