Baryon number violating nuclear decay

The expressions for baryon number violating nuclear partial decay widths are derived from the interactions as predicted by grand unified theories. Theory predicts that the baryon number violating proton decay inside the nucleus is hindered relative to the free proton decay rate. In the case of closed shell nuclei, the meson spin-isospin dependence of the partial width is the same as that for the nucleon decay. The branching ratios of decay amplitudes depend on the nuclear binding energies. Nuclear structure introduces lepton energy spread of ±49.5 MeV for light closed shell nuclei, while it does not affect the back to back emission of lepton-meson pair.     

Baryon poles in proton decay amplitudes

The decay rate of the p→π⁰e⁺ mode is calculated in SU(5) grand unified theory using a pole model with proton and $\text{1}\text{2}{}^{\mathrm{?}}$ baryon poles. Baryon-to-vacuum amplitudes are calculated in the framework of the MIT bag model. It is found that the partial decay rate [～(5×10³¹ yr)^?)] is close to the partial decay rates calculated by different methods.     

Baryon wave functions and nucleon decay

We apply to nucleon decay the knowledge about the short-distance structure of baryon wave functions gleaned from QCD form factor calculations nd the $\text{J}\text{gY →}\text{p}\text{?}\text{p}$ decay rate. We review the uncertainties arising when current algebra and PCAC are used to relate $\text{N}\text{→}\text{?}\text{+}$ meson decay rates to 〈0|qqq|N〉 matrix elements. We show that the relevant matrix elements are not directly related to those of the leading twist operators “measured” in conventional high momentum transfer physics, but argue for an indirect based on models that fit both form factor and $\text{J}\text{Ψ}$ decay data. We use these inputs to calculate the p → e⁺π⁰ decay rate in minimal SU(5) and other grand unified theories (GUTs) for a specified value of the heavy vector boson mass m_X. Our results combined with the recent experimental lower limit on this mode indicate that m_X > 2 × 10¹⁵ GeV in the minimal SU(5) GUT, and we derive analogous bounds for supersymmetric GUTs. Our calculated lifetime for a given value of m_X is considerably shorter than previous estimates made using non-relativistic SU(6) or the bag model, a difference traceable to the different normalizations of 2 and 3 quark wave functions at short distances.     

Baryon asymmetry and nucleon decay in supersymmetric guts

In a class of supersymmetric GUTs with a coloured Higgs sector of an intermediate mass, we study nucleon decay and the generation of baryon assymmetry. We find that: (a) a non-vanishing baryon asymmetry can be generated by the decay of coloured Higgs bosons and Higgs fermions into quarks and squarks; (b) nucleons decay at a rate 10^?31 yr^?1 preferably to $\text{μ}{}^{\mathrm{+}}\text{K}{}^0\text{,}\text{ν}{}_{\mathrm{\mu }}\text{K}{}^{\mathrm{+}}$ while decay involving dimension-five operators is kinematically excluded.     

Baryon decay of excited states of 1P-shell hypernuclei

The baryon decays of hypernuclear resonances with the configurations s_⃛p⁻¹, p_⃛p⁻¹, and s_⃛s⁻¹ are analyzed within the framework of a translationally invariant shell model. Particular attention is paid to the influence of the nuclear structure on the decay probabilities in different channels. Joint Institute of Nuclear Research, Dubna. Institute of Nuclear Physics, Czech, Republic, Rzhezh. Institute of Nuclear Research, Russian Academy of Sciences, Moscow. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 35–51, October, 1997.     

Baryon form factors in chiral perturbation theory

We analyze the electromagnetic form factors of the ground state baryon octet to fourth order in relativistic baryon chiral perturbation theory. Predictions for the charge radius and the – transition moment are found to be in excellent agreement with the available experimental information. Furthermore, the convergence behavior of the hyperon charge radii is shown to be more than satisfactory. Received: 25 October 2000 / Published online: 23 January 2001     

Effects of multiplicity on charm semileptonic decay distributions

We consider the effects of multiplicity in semileptonic decays of charmed D(1.87) mesons, produced near threshold in e⁺e^? collisions. We calculate the decay distributions from uncorrelated D → (nπ)Kev and resonance dominated $\text{D}\text{→}\text{K}{}^1\text{e}\text{v}$ modes. Recent data from DORIS suggest that modes with two or more final hadrons dominate strongly.     

Extracting the charm cross-section from its semileptonic decay at RHIC

We propose a sensitive measurement of the charm total cross-section at RHIC through muon identification from charm semileptonic decay at low transverse momentum (pT$p_T$). This can test the binary-collision scaling (Nbin$N_{\mathrm{bin}}$) properties of the charm total cross-section and be used to study whether heavy-flavor quarks, which are used as a probe, are produced exclusively at the initial impact in hadron–hadron collisions. The effect of the charm semileptonic decay form factor on extracting the total charm cross section and on the shape of the lepton spectra are also discussed in detail. We conclude that lepton spectra from charmed hadron decays at transverse momentum pT?1.0 GeV/c$p_T?1.0\text{GeV}/c$ are sensitive to the charmed hadron spectrum shape. Therefore, the interactions of heavy quarks with the medium created in relativistic heavy-ion collisions, especially the flow effects, can be extracted from the lepton spectra from charmed hadron decays at low pT$p_T$.     

Direct observations of the decay of beauty particles into charm particles

The associated production of a pair of beauty particles B^? and $\text{B}{}^0$ by a 350 GeV π^? interaction has been observed in an emulsion target inserted in an array of silicon microstrip detectors. Both beauty particles decay into charm particles, both of which are also observed to decay in the emulsion. Two negative muons were identified and their momenta measured in a large muon spectrometer. One muon has a p_T of 1.9 GeV/c and is associated with a beauty particle decay. The other, with a p_T of 0.45 GeV/c is associated with a charm particle decay. The flight times of the two beauty particles are respectively (0.8 ± 0.1) × 10^?13 s and (5⁺²_?1) × 10^?13 s. Alternative interpretations of this event have negligible probability.     

Baryon chiral perturbation theory in manifestly Lorentz invariant form

We show that in the presence of massive particles, such as nucleons, the standard low-energy expansion, in powers of meson momenta and light-quark masses, in general converges in only part of the low-energy region. The expansion of the scalar form factor , for instance, breaks down in the vicinity of . In the language of heavy baryon chiral perturbation theory, the proper behaviour in the threshold region results only if the multiple internal-line insertions generated by relativistic kinematics are summed up to all orders. We propose a method that yields a coherent representation throughout the low-energy region, while keeping Lorentz and chiral invariance explicit at all stages. The method is illustrated with a calculation of the nucleon mass and of the scalar form factor to order .     

Baryon spin-parity tests using polarized proton targets or beams

A new method is proposed for performing combined spin and parity tests on baryon resonances generated in quasi-two-body production experiments, without any dynamical hypothesis, using polarized proton targets or beams. These tests present the advantage of being applicable to data averaged over intervals of momentum transfer and mass. In order to estimate the sensitivity of the tests to experimental errors, a simulated experiment with random errors is analysed, and quite good stability is found.     

Potential of deep-underwater neutrino telescopes for recording muons from charm decay

Within several models of charm production in hadron-nucleus interactions, it is shown that prompt-muon fluxes at the depths of operating and designed neutrino telescopes (1–4 km) can in principle be measured in experiments with a high detection threshold.     

一个新的、相对论性的、无奇异点的重子顶点形状因子

提出了交叉道研究中的一种新的、相对论性的、无奇异性的顶角形状因子. 使用该形状因子的散射振幅具有从t道到s道或从s道到t道的交叉对称性.     

Tests for the charm changing charged current in lepton-hadron scattering

Starting from a weak charged hadronic current whose ΔC = 1 part is a general mixture of vector and axial vector currents, we work out experimental distributions of interest in inclusive and semi-inclusive lepton-hadron processes. Detailed consequences for the Cabibbo, Glashow-Iliopoulos-Maiani and De Rujula-Georgi-Glashow currents are presented. Special importance of the measurement of hadron multiplicities in the low-x region as a tool to probe the chiral structure of the charm changing current is pointed out.     

Pure annihilation decay of strange beauty meson into two charm heavy mesons

In this study, the heavy to heavy decay of \begin{document}$ B^0_s\rightarrow D^{*+}D^- $\end{document} is evaluated through the factorization approach by using the final state interaction as an effective correction. Under the factorization approach, this decay mode occurs only through the annihilation process, so a small amount is produced. Feynman's rules state that six meson pairs can be assumed for the intermediate states before the final meson pairs are produced. By taking into account the effects of twelve final state interaction diagrams in the calculations, a significant correction is obtained. These effects correct the value of the branching ratio obtained by the pure factorization approach from \begin{document}$ (2.41\pm1.37)\times10^{-5} $\end{document} to \begin{document}$ (8.27\pm2.23)\times10^{-5} $\end{document}. The value obtained for the branching ratio of the \begin{document}$ B^0_s\rightarrow D^{*+}D^- $\end{document} decay is consistent with the experimental results.