Weak Quasielastic Hyperon Production Leading to Pions in the Antineutrino-Nucleus Reactions

Abstract

In this review, we have studied the quasielastic production cross sections and polarization components of Λ, Σ 0 and Σ − hyperons induced by the weak charged currents in the antineutrino reactions on the nucleon and the nuclear targets like 12 C, 16 O, 40 Ar and 208 Pb. It is shown that the energy and the Q 2 dependence of the cross sections and the various polarization components can be effectively used to determine the axial vector transition form factors in the strangeness sector and test the validity of various symmetry properties of the weak hadronic currents like G-invariance, T-invariance and SU(3) symmetry. In particular, the energy and the Q 2 dependence of the polarization components of the hyperons is found to be sensitive enough to determine the presence of the second class current with or without T-invariance.These hyperons decay dominantly into pions giving an additional contribution to the weak pion production induced by the antineutrinos. This contribution is shown to be quantitatively significant as compared to the pion production by the ∆ excitation in the nuclear targets in the sub-GeV energy region relevant for theνµ cross section measurements in the oscillation experiments. We have also included a few new results, based on our earlier works, which are in the kinematic region of the present and future (anti)neutrino experiments being done with the accelerator (anti)neutrinos at T2K, MicroBooNE, MiniBooNE, NOνA, MINERνA and DUNE, as well as for the atmospheric (anti)neutrino experiments in this energy region.

Status and perspectives of neutrino physics

“…For details, please see Ref. [407,408]. Historically, the axial vector form factor g 1 (q 2 ) has been parameterized as a dipole given by…”

“…These nuclear medium effects play an important role in the final state composition, in interpreting the experimental results, and in the determination of M A in nuclear target data. It has been also observed that the quasi-elastic hyperon production induced by antineutrino scattering can give significant contribution to the pion production arising due to the hyperon decay and is comparable to the pions arising due to ∆ decay in nuclear targets in the sub-GeV energy region relevant for atmospheric and accelerator experiments being performed to study neutrino oscillation phenomenona [407,[411][412][413].…”

Weak production of strange Ξ baryons off the nucleon

“…It is worth noticing that Eqs. (8) and (9) are generally expressed for the SU (3) couplings. However, it has been shown by previous authors [3,4] that such relationships work well for finite q 2 too.…”

“…In last decade there were several attempts to explore the strangeness physics in weak sector [1,2]. The quasielastic production of hyperons [3][4][5][6] and their subsequent decay into pions [7,8] have been recently analyzed around ∼ 1 GeV anti-neutrino energies. Experimental efforts are also made to observe such processes [9].…”

Quasielastic production of polarized $τ$ leptons in $ν_τ$ and $\barν_τ$ scattering from nucleons

“…In this work, we study the effect of using various parametric forms of the weak vector and axial vector form factors as well as the effect of pseudoscalar and second class current form factors in the axial vector sector on the total cross section, differential cross section and the polarization components of τ leptons produced in the quasielastic ν τ (ν τ )−nucleon scattering following our earlier works in the case of ν µ (ν µ )−nucleon scattering [17,[41][42][43]. In section II, we define the matrix element in terms of the various weak form factors and describe their properties under symmetry transformations and express the differential cross sections in terms of these form factors.…”