Weak Radiative Decays of Hyperons and Charmed Baryons in SU(4) and SU(8) (original) (raw)

1977, Progress of Theoretical and Experimental Physics

We study the weak radiative decays of uncharmed and charmed baryons in the SU(4) and SU(S) symmetry framework. \Ve find that the GIM model of weak interactions gives unsatisfactory results for the weak radiative decays of uncharmed baryons, at SU(4) leveL An admixture of 15-dimensional representation of SU(4) in the GIM weak Hamiltonian is indicated. We propose measurement of the decay z->.s-r in order to elucidate the structure of the weak Hamiltonian. § 1. Introduction Weak radiative decays of hyperons have been discussed by several authors 11 in the domain of SU(3) symmetry. The available experimental information about these decays is meagre. Definite numbers have been reported for the process 2+-'>Pt only. We have 21 T(2~-'>Pt)_ = (1.43±0.26) X 10-3 r (2+->all) and the asymmetry parameter a for this decay is (-1.03:':UD. Even this small information about the weak radiative decays has been a source of considerable difficulty for the weak interaction phenomenology. In the current ~ current model of weak interactions, if one assumes the same behaviour under C (charge conjugation) for the parity violating (pv) and parity conserving (pc) parts of the weak Hamiltonian the asymmetry parameter for 2+ decay turns out to be zero. 11 A small negative value for a can be obtained in pole models by making certain assumptions about the intermediate states. 31 " 11 But a large value of a (2+->Pr) remains unexplained. A simple way out is to assume that the pv and pc parts of the weak Hamiltonian have opposite behaviour under C. This means that at the SU(3) level one assumes the pv Hamiltonian to transform as }., component of the octet and the pc Hamiltonian to transform as J.6 • This choice for the weak Hamiltonian has already been proposed in the context of quark-density model, 51 and has the attractive feature that K,->27r is not zero in the SU(3) limit. This SU(3) structure for the weak Hamiltonian is also obtained in recent models with right-handed currents. 61 With this assumption, both pv and pc parts of the weak Hamiltonian transform similarly under CP and the amplitude for S"-'>Pt is non-zero in both

Non-Leptonic Decays of Hyperons and of Charmed Baryons in SU(8)

Progress of Theoretical Physics, 1977

Non-leptonic weak decays of hyperons and of charmed baryons are investigated within the framework of SU(S) and SU(S)w on the assumption that weak interaction is of the current® current form (the currents being of the GIM type) and is CP invariant. We find that SU(S) conveys more information about pv decays than SU(4). Several relations in addition to the ones obtained in SU(4) are obtained. The assumption of 20"-dominance at the SU(4) level is no longer required for the pv decays of the hyperons. Unlike in SU(6)w we are able to get the Lee-Sugawara sum rule for pc decays in SU (8) w without being forced to take ~!=0. § I. Introduction Non-leptonic weak decays of Hyperons!) and of charmed particles 2 > have been discussed on the basis of SU(4) symmetry. On the basis of the idea of spin-unitary

Analysis ofΔS=1nonleptonic weak decays and theΔI=12rule

Physical review, 1980

Current-algebra and quark-model methods are used to investigate hyperon and kaon transition amplitudes for various contributions to the weak nonleptonic Hamiltonian of the Weinberg-Salam model. Substantial enhancements are found for matrix elements of certain operators which are induced by quantumchromodynamic radiative corrections and contain right-handed currents. These operators improve the agreement with experiment in most cases, although problems remain in P-wave hyperon amplitudes. In this approach, the AI = 1/2 rule is understandable in both kaons and baryons under plausible assumptions.

Radiative Decays of Vector Mesons in Broken SU(3)

Progress of Theoretical Physics, 1980

\Ve propose that the effect of the medium strong symmetry breaking interaction on the hadronic electromagnetic processes can be taken into account by working with an octet· dominant effective electromagnetic Hamiltonian transforming as S. '+bS,' in SU(3). This simple prescription suffices to explain most of the data on the radiative decays. The analysis presents a strong case for the accurate measurement of T(K*'--'>K'r) and of the ratio T(K*+ --'>K+r) /T(K*'--'>K'r). \Ve extend the symmetry breaking formalism to the SU (4) -charm scheme. § 1. Introduction Over the last few years a large amount of information on the radiative decays of vector mesons (V ---'>Pr) has become available. 1 l The new data have caused serious apprehensions about the validity of SU (3) -symmetry for the electromagnetic phenomena. As the results on the measurements of V ---'>Pr decays through the Primakoff effect started coming in, Edwards and Kamal") immediately tried to fit the decay widths in models incorporating SU (3) -violations at the V Pr-vertex, and

Theory of Heavy Baryon Decay 1

We discuss various topics in the theory of heavy baryon decays. Among these are recent applications of the Relativistic Three Quark Model to semileptonic, non-leptonic, one-pion and one-photon transitions among heavy baryons, new higher order perturbative results on the correlator of two heavy baryon currents and on the semi-inclusive decay Λ b → X c + D

Low-energy weak interactions of quarks

Physics Reports, 1986

Introduction 321 6.1. Data and kinematics 2. General background of the standard model 322 6.2. Theoretical procedures 2.1. Conventions 322 6.3. Baryonic I1S~= 1 decays 2.2. Electroweak (SU(2)L x 1.1(1)) interactions 322 6.4. Kaon decays 2.3. Strong (SU(3)~) interactions 324 7. Other decay modes 3. A users guide to the quark model 327 8, Physics of the K°K°system 3.1. Spin-color wavefunctions 327 8.1. Overview 3.2. Spatial wavefunctions 330 8.2. Short distance physics 3.3. Connection with plane wave states 335 8.3. The B parameter 3.4. How to calculate matrix elements 336 8.4. Long distance physics 3.5. Limitations to the quark model approach 338 8.5. The KL-KS mass difference 4. Nuclear beta decay 339 8.6. CP-violation 4.1. Tests of CVC 342 9. Nuclear parity violation 4.2. Second class currents 344 10. Weak decays of hypernuclei 4.3. Tests of PCAC 345 11. Recent developments 5. Semileptonic weak decays 348 11.1. Nonleptonic interactions and lattice gauge theory 5.1. Hyperon beta decay 348 11.2. Nonleptonic interactions of chiral solitons 5.2. ii-and K decay 355 12. Conclusions 6.~= 1 hadronic decays 356 References

Strong decays of strange quarkonia in a corrected P03 model

Physical Review C

Extensively applied to both light and heavy meson decay and standing as one of the most successful strong decay models is the 3 P0 model, in which qq pair production is the dominant mechanism. In this paper we evaluate strong decay amplitudes and partial widths of strange S and D state mesons, namely φ(1020), φ(1680), φ(2050), φ1(1850), φ2(1850) and φ3(1850), in the bound-state corrected 3 P0 decay model (C 3 P0). The C 3 P0 model is obtained in the context of the Fock-Tani formalism, which is a mapping technique.

Semi-weak interactions and the nonleptonic hyperon decays

Il Nuovo Cimento A, 1973

We modify the pole model for the nonleptonie weak decays by considering the three-and two-particle vertices as semi-weak interactions instead of strong and weak ones. This gives excellent agreement with experiment for both the sand p-wave amplitudes with only the 89 poles. The method is also applied to the AS= 1 radiative decays, and it is seen that the only experimental result (F and ~ of Z+->py) can be derived through a rather interesting connection between the parameters involved in B-+B'~: and B~B',f.

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