Estimations of pi0 production from charge pion in CC, model dependencies, simulation studies

1. Estimations of pi0 production from charge pion in CC, model dependencies, simulation studies Some preliminary considerations pawel, 20-06-2007

2. Generator and stats • Generator: Nuance 3.006 • Medium: water • With and without nuclear reinteractions • 500,000 evts generated • 210873 cc and 83378 nc events – QE • 112776 cc  and 42856 nc events – RES • 27187 cc  and 9250 nc events – DIS • And others, more exotic (diffractive, coherent, elastic on electrons)

3. Beam structure (after interactions) All QE All DIS

4. Multiplicity of final states CC CC All All NC NC No intranuclear interactions Intranuclear interactions included

5. Single pi zero production Qsq<0.2 All One pizero evts All Qsq>0.2 Pizero momentum distributions Ntuple Qsquare distributions

6. Qsquare considerations Outgoing lepton Neutrino Qsq = four-momentum transfer Nucleon • Ideal qsquare – from lepton vertex • Observable qsquare – from hadron vertex, assuming nucleon doesn’t have a fermi momentum • We have to take into account additional nucleons in the hadron vertex (calculating it in real detector environment is a totally different issue:-) Hadrons

7. Qsquare – true and observable All (w/o exotic) QE Solid – lepton qsq, dashed – hadron qsq

8. Qsquare – true and observable NC 1pizero CC 1piplus Solid – lepton qsq, dashed – hadron qsq

9. The same compared differently Lepton qsq Hadron qsq Solid – NC1piz, dashed – CC1pipl

10. Lepton qsq, RES and DIS Solid – NC1piz, dashed – CC1pipl

11. Let’s include FSIs Solid – no FSIs, Dashed – FSIs included (hadron qsq) QE All (w/o exotic) FSIs smear qsq distribution a little, but nothing unexpected

12. FSIs: single pi production evts Solid – no FSIs, Dashed – FSIs included NC 1pizeronoFSI: 28685evts,FSI: 21484evts CC 1piplus,noFSI: 109421evts,FSI: 86276evts Turning on FSIs means that some pis are produced in the cascade, changing the event signature from ‘single pi’ to ‘multi pi’, that’s why there’s more ‘single pi’ in the noFSI sample

13. FSIs single pi - shapes Solid – no FSIs, Dashed – FSIs included NC 1pizero CC 1piplus When we compare shapes only (both distr normalized) we see smearing again

14. Closer look at the hadron vertex Outgoing lepton Neutrino Nucleon Δ Hadrons • For one pi production events we can safely (?) assume delta as an intermediate particle • Total momentum from hadrons, energy calculating using delta mass (1232MeV) • But what if (possible source of problems): Nucleon Δ Hadrons Additional hadrons, e.g. nucleons

15. Delta assumption: pi production evts Solid – normal hadron qsq, Dashed – delta assumption NC 1pizero CC 1piplus Delta qsq: wide peak at -2 plus much more evts for high qsq