0000000000371053
AUTHOR
F. Hussain
Covariant foundation of heavy hadron decays
Abstract I present a covariant formulation of heavy hadron decays in the formal limit of MQ → ∞. This allows for an elegant way to implement the symmeteries found by Isgur and Wise in this limit. I also discuss a Bloch-Nordsieck formulation of this limit and leading log corrections.
SARS-CoV-2 vaccination modelling for safe surgery to save lives: data from an international prospective cohort study
Abstract Background Preoperative SARS-CoV-2 vaccination could support safer elective surgery. Vaccine numbers are limited so this study aimed to inform their prioritization by modelling. Methods The primary outcome was the number needed to vaccinate (NNV) to prevent one COVID-19-related death in 1 year. NNVs were based on postoperative SARS-CoV-2 rates and mortality in an international cohort study (surgical patients), and community SARS-CoV-2 incidence and case fatality data (general population). NNV estimates were stratified by age (18–49, 50–69, 70 or more years) and type of surgery. Best- and worst-case scenarios were used to describe uncertainty. Results NNVs were more favourable in su…
General analysis of weak decay form factors in heavy to heavy and heavy to light baryon transitions
We present a complete analysis of the heavy to heavy and heavy to light baryon semi-leptonic decays in the heavy quark effective theory within the framework of a Bethe-Salpeter (BS) approach and demonstrate the equivalence of this approach to other work in the field. We present in a compact form the baryon BS amplitudes which incorporate the symmetries manifest in the heavy quark limit and which also show clearly the light quark dynamics. A similar form of the BS amplitude is presented for light baryons. Using the BS amplitudes, the heavy to heavy and heavy to light semi-leptonic baryon decays are considered. As expected there is a dramatic reduction in the number of form factors. An advant…
Exclusive semi-leptonic decays of bottom baryons
Abstract We calculate the exclusive semi-leptonic bottom baryon decays Λ b →Λ c +l − + v l , Σ b → Σ c +l − + v l and Σ b →Σ c ∗ +l − + v l in the spectator quark model. The helicity structure of the baryonic current transitions Λb→Λc, Σ b →Σ c (Σ c ∗ ) is matched to the helicity structure of the free quark current transitions b → c at minimum momentum transfer q2 = 0. The results are continued to q2≠0 by pole dominated form factors. We obtain semi-leptonic baryonic decay rates which are close to the corresponding semi-leptonic mesonic decay rates.
Relativistic SU(6) wave functions as the basis of modern approaches to hadronic wave functions
The connections between various models of hadrons and the relativistic SU(6) wave functions are established. In formal terms and by concrete example it is shown how the Bargman-Wigner fields of freely moving quarks and antiquarks of equal velocity form the basis of the above approaches. This places modern attempts in their historical setting and allows for a more unified analysis of the various schemes.
Covariant trace formalism for heavy mesons-wave top-wave transitions
Heavy meson,s- top-wave, weakb→c transitions are studied in the context of the heavy quark effective theory using covariant meson wave functions. We use the trace formalism to evaluate the weak transitions. As expected from heavy quark symmetry, the eight transitions betweens- andp-wave states are described in terms of only two universal form factors which are given in terms of explicit wave function overlap integrals. We present our results in terms of both invariant and helicity amplitudes. Using our helicity amplitude expressions we discuss rate formulae, helicity structure functions and joint angular decay distributions in the decays $$\bar B \to D^{**} ( \to (D,D^* ) + \pi ) + W^ - ( \…
Non-commutative geometry and supersymmetry II
Abstract Extending results of a previous work [Phys. Lett. B 260 (1991) 359], we establis that anothe non-commutative model proposed by Balakrishna, Gursey and Wali may be expressed as a Yang-Mills theory of a graded Lie group.
On heavy baryon decay form factors
We consider in detail the consequences of the heavy quark mass limit in the weak decay of 1/2+ heavy baryons to 1/2+ and 3/2+ heavy baryon final states. We also analyze heavy baryon to light baryon transitions as well ase+e−-annihilation into heavy baryon-antibaryonpairs. We discuss possible approximations to the most general approach and some of their implications for future experiments.
Semi-leptonic charm baryon decays in the relativistic spectator quark model
We calculate the exclusive semi-leptonic charm baryon decays of the lowest lying charm baryon states into the ground state strangeness baryons using the covariant spectator quark model approach. We present results on rates,q 2- andE l -spectra as well as on the angular decay distribution in the cascade decay $$\Omega _c \to \Omega ( \to \Xi \pi ,\Lambda {\rm K})$$ .