Polarization of τ in quasielastic (anti)neutrino scattering: The role of spectral functions

Abstract

We present a study of the τ polarization in charged-current quasielastic (anti)neutrino-nucleus scattering. The spectral function formalism is used to compute the differential cross section and the polarization components for several kinematical setups, relevant for neutrino-oscillation experiments. The effects of the nuclear corrections in these observables are investigated by comparing the results obtained using two different realistic spectral functions, with those deduced from the relativistic global Fermi gas model, where only statistical correlations are accounted for. We show that the spectral functions, although they play an important role when predicting the differential cross sections, produce much less visible effects on the polarization components of the outgoing τ .PACS numbers: 13.15.+g,13.60.r arXiv:1906.05656v1 [nucl-th]

Tau neutrinos at DUNE: New strategies, new opportunities

“…Ultimately, several physics analyses could benefit from applying our tool chain with realistic detector effects and a treatment of systematic uncertainties. Amongst those are ν τ -nucleus interaction measurements [6,21]; violations of unitarity in the leptonic mixing matrix [23,25,[48][49][50]; nonstandard neutrinos interactions in neutrino production, detection and propagation [51]; sterile neutrino searches [52][53][54][55]; and general consistency tests of the three neutrino oscillation paradigm [24,28]. In our work we demonstrate that the tau-optimized beam significantly enhances the prospects of tau neutrino measurements at DUNE.…”

“…Despite such difficulties, upcoming multipurpose neutrino experiments, such as DUNE [14], are well posed to detect tau neutrinos given their large fiducial volume, powerful neutrino beam and exquisite track reconstruction capability. There have been a number of works which explore the tau neutrino sector including pioneering proposals for observing ν τ at beam dump experiments [15] and the subsequent experimental search by NOMAD [16], polarization effects on τ decay products for atmospheric and beam ν τ searches [17][18][19][20][21], optimization of cuts on τ decay products in the DUNE beam neutrino sample [22], tests of unitarity and patterns of leptonic mixing [23][24][25] and beyond the Standard Model physics probes with ν τ measurements [26][27][28][29].…”

Hyperon production in quasielastic $\barν_τ-$nucleon scattering

“…As the energy increases, the production of the τ leptons is accompanied with the inelastic and deep inelastic production of hadrons. In the energy region of ν τ (ν τ ) experiments, where the energy of the produced τ lepton is not too large compared to its rest mass m τ = 1.776 GeV, the τ leptons would not be completely longitudinally polarized, and would also have transverse component of the polarization [17][18][19][20][21][22][23][24]. Moreover, any presence of the polarization component perpendicular to the reaction plane would provide information about the T noninvariance in ν τ − N interactions [25][26][27][28].…”

Nuclear medium effects in the deep inelastic $ν_τ/\barν_τ-^{40}Ar$ scattering at DUNE energies

“…But a serious attempt to study these effects quantitatively has been lacking except for the earlier work of Paschos and Yu [20] in which the nuclear medium effects in the ν τ −nucleus scattering in the deep inelastic region has been incorporated at the leading order (LO) in the massless limit of quarks using the phenomenological nuclear structure functions of Eskola et al [26] and Hirai et al [27]. However, some recent work has been done to discuss the nuclear medium effects in the cross sections and polarization of τ leptons produced in the ν τ induced quasielastic scattering [28,29] but not in the case of deep inelastic scattering induced by ν τ . This is in contrast to the study of the deep inelastic scattering induced by the electron neutrinos (ν e ) and muon neutrinos (ν µ ) from nuclei in which the nuclear medium effects have been studied extensively [30][31][32][33][34][35][36][37][38][39][40][41].…”