Antineutrino inducedΛ(1405)production off the proton

Abstract

We have studied the strangeness changing antineutrino induced reactionsν l p → l + φB, with φB = K − p,, using a chiral unitary approach. These ten coupled channels are allowed to interact strongly, using a kernel derived from the chiral Lagrangians. This interaction generates two Λ(1405) poles, leading to a clear single peak in the πΣ invariant mass distributions. At backward scattering angles in the center of mass frame,νµp → µ + π 0 Σ 0 is dominated by the Λ(1405) state at around 1420 MeV while the lighter state becomes relevant as the angle decreases, leading to an asymmetric line shape. In addition, there are substantial differences in the shape of πΣ invariant mass distributions for the three charge channels. If observed, these differences would provide valuable information on a claimed isospin I = 1, strangeness S = −1 baryonic state around 1400 MeV. Integrated cross sections have been obtained for the πΣ andKN channels, investigating the impact of unitarization in the results. The number of events with Λ(1405) excitation inνµp collisions in the recent antineutrino run at the MINERνA experiment has also been obtained. We find that this reaction channel is relevant enough to be investigated experimentally and to be taken into account in the simulation models of future experiments with antineutrino beams.

Weak decays of heavy hadrons into dynamically generated resonances

“…Very recently it has also been suggested that the neutrino induced production of the Λ(1405) is a good tool to further investigate the properties and nature of this resonance. 270 The basic feature in the dynamical generation of the Λ(1405) in the chiral unitary approach is the coupled channel unitary treatment of the interaction between the coupled channels K − p,K 0 n, π 0 Λ, π 0 Σ 0 , ηΛ, ηΣ 0 , π + Σ − , π − Σ + , K + Ξ − , and K 0 Ξ 0 . The coupled channels study allows us to relate the K − p and πΣ production, where the resonance is seen, and this is a unique feature of the nature of this resonance as a dynamically generated state.…”

Theoretical tools for neutrino scattering: interplay between lattice QCD, EFTs, nuclear physics, phenomenology, and neutrino event generators

“…Unitarization, which becomes important as W increases, is absent in tree-level amplitudes but can be partially restored by imposing Watson's theorem in relevant multipoles [479,480]. For neutrino interactions, a complete unitarization in coupled channels has only been implemented by the DCC model [397][398][399] and in the strangeness S = −1 sector within the chiral-unitary approach [481]. High invariant masses W 2 GeV, above the resonance region and low Q 2 is the realm of diffractive scattering where non-resonant amplitudes need to be improved within the Regge approach [482][483][484].…”

Weak kaon production off the nucleon and Watson's theorem

“…Theoretical work on weak production of meson-baryon pairs with open and hidden strangeness was performed in the early days of neutrino physics [9][10][11][12] and resumed only recently with studies in the ∆S = 0 [13,14], ∆S = −1 [15,16] and ∆S = 1 [1] sectors. The first calculation of the ν l N → l − KN amplitudes using leadingorder SU(3) chiral perturbation theory was performed by Alam et.…”