<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>T</mml:mi></mml:math>-Violation Effects and Final-State Interactions. II. Photoproduction, Electroproduction, and Neutrino-Induced Production of a Single Pion

Cannata, F.; Leonardi, R.; Strocchi, Franco

doi:10.1103/physrevd.1.191

Cited by 9 publications

(15 citation statements)

References 8 publications

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“…and therefore (L (ν) ) µν W µν is not T −invariant either, because of the presence of the PV terms in the hadronic tensor 18 . This does not necessarily means that there exists a violation of T −invariance in the process because of the existence of strong final state interaction effects [45,46]. With our election of kinematics ( k, k ′ in the XZ plane), we find (L…”

Section: Discussionmentioning

confidence: 84%

“…This does not necessarily means that there exists a violation of T −invariance in the process because of the existence of strong final state interaction effects [45,46].…”

Section: Appendix A: Dependence Of the Neutrino Differential Cross Sementioning

confidence: 99%

“…Moreover, these terms also induce T −odd correlations in the (L (ν,ν) ) µν W µν contraction (see Eqs. (A1)-(A7) in the Appendix A), which do not imply a genuine violation of time reversal invariance because of the existence of strong final state interaction effects 16 [45,46].…”

Section: A CC Pion Production Cross Sectionsmentioning

confidence: 99%

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Weak pion production off the nucleon

2007

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We develop a model for the weak pion production off the nucleon, which besides the Delta pole mechanism (weak excitation of the ∆(1232) resonance and its subsequent decay into N π), includes also some background terms required by chiral symmetry. We re-fit the C A 5 (q 2 ) form factor to the flux averaged νµp → µ − pπ + ANL q 2 −differential cross section data, finding a substantially smaller contribution of the Delta pole mechanism than traditionally assumed in the literature. Within this scheme, we calculate several differential and integrated cross sections, including pion angular distributions, induced by neutrinos and antineutrinos and driven both by charged and neutral currents. In all cases we find that the background terms produce quite significant effects and that they lead to an overall improved description of the data, as compared to the case where only the Delta pole mechanism is considered. We also show that the interference between the Delta pole and the background terms produces parity-violating contributions to the pion angular differential cross section, which are intimately linked to T −odd correlations in the contraction between the leptonic and hadronic tensors. However, these latter correlations do not imply a genuine violation of time reversal invariance because of the existence of strong final state interaction effects.

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Section: Discussionmentioning

confidence: 84%

“…This does not necessarily means that there exists a violation of T −invariance in the process because of the existence of strong final state interaction effects [45,46].…”

Section: Appendix A: Dependence Of the Neutrino Differential Cross Sementioning

confidence: 99%

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Weak pion production off the nucleon

2007

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“…(C22) can also be obtained from the expressions given in Eqs. (30) and (31), taking advantage that in the zero lepton mass limit, the non-zero components of the lepton tensor L µν (k * , k * ) read,…”

Section: Zero Lepton Mass Limitmentioning

confidence: 99%

“…The terms proportional to sin φ * π and sin 2φ * π in Eq. (30) give rise to parity violation in the weak dσ/(dΩ dE dΩ * π ) and dσ/(dQ 2 dW πN dΩ * π ) differential cross sections [10,11]. The reason is the following.…”

Section: Pion Production Differential Cross Section Parity Violating ...mentioning

confidence: 99%

Angular distributions in electroweak pion production off nucleons: Odd parity hadron terms, strong relative phases, and model dependence

et al. 2018

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The study of pion production in nuclei is important for signal and background determinations in current and future neutrino oscillation experiments. The first step, however, is to understand the pion production reactions at the free nucleon level. We present an exhaustive study of the chargedcurrent and neutral-current neutrino and antineutrino pion production off nucleons, paying special attention to the angular distributions of the outgoing pion. We show, using general arguments, that parity violation and time-reversal odd correlations in the weak differential cross sections are generated from the interference between different contributions to the hadronic current that are not relatively real. Next, we present a detailed comparison of three, state of the art, microscopic models for electroweak pion production off nucleons, and we also confront their predictions with polarized electron data, as a test of the vector content of these models. We also illustrate the importance of carrying out a comprehensive test at the level of outgoing pion angular distributions, going beyond comparisons done for partially integrated cross sections, where model differences cancel to a certain extent. Finally, we observe that all charged and neutral current distributions show sizable anisotropies, and identify channels for which parity-violating effects are clearly visible. Based on the above results, we conclude that the use of isotropic distributions for the pions in the center of mass of the final pion-nucleon system, as assumed by some of the Monte Carlo event generators, needs to be improved by incorporating the findings of microscopic calculations.

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Can one distinguish τ-neutrinos from antineutrinos in neutral-current pion production processes?

Hernández¹,

Nieves

Valverde

2007

Physics Letters B

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A potential way to distinguish τ −neutrinos from antineutrinos, below the τ −production threshold, but above the pion production one, is presented. It is based on the different behavior of the neutral current pion production off the nucleon, depending on whether it is induced by neutrinos or antineutrinos. This procedure for distinguishing τ −neutrinos from antineutrinos neither relies on any nuclear model, nor it is affected by any nuclear effect (distortion of the outgoing nucleon waves, etc...). We show that neutrino-antineutrino asymmetries occur both in the totally integrated cross sections and in the pion azimuthal differential distributions. To define the asymmetries for the latter distributions we just rely on Lorentz-invariance. All these asymmetries are independent of the lepton family and can be experimentally measured by using electron or muon neutrinos, due to the lepton family universality of the neutral current neutrino interaction. Nevertheless and to estimate their size, we have also used the chiral model of hep-ph/0701149 at intermediate energies. Results are really significant since the differences between neutrino and antineutrino induced reactions are always large in all physical channels.

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T-Violation Effects and Final-State Interactions. II. Photoproduction, Electroproduction, and Neutrino-Induced Production of a Single Pion

Cited by 9 publications

References 8 publications

Weak pion production off the nucleon

Weak pion production off the nucleon

Angular distributions in electroweak pion production off nucleons: Odd parity hadron terms, strong relative phases, and model dependence

Can one distinguish τ-neutrinos from antineutrinos in neutral-current pion production processes?

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