Neutrino nucleus reactions at high energies within the GiBUU model

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1 Neutrino nucleus reactions at high energies within the GiBUU model Olga Lalakulich, Kai Gallmeister, Tina Leitner, Ulrich Mosel Universität Giessen 1

2 Motivation Neutrino oscillations discovered 1998 Modern Experiments K2K Detectors = Targets are NUCLEI (CH2, C8H8, Fe, Pb) CNGS MiniBooNE MINOS, Miner a T2K Accelerator neutrinos = Neutrino-nucleus cross sections are needed as input parameters with as high accuracy as possible 2

3 Motivation Measuring parameters of neutrino oscillations MINOS and Miner a experiments 3

4 GiBUU model the semiclassical transport model in couple channels simulates the transport of hadrons through nuclear matter in space and time GiBUU describes several reactions in resonance and high energy regions, is extensively checked against experimental data for A, A, e- A, A Aim: many reactions with one microscopic model Open source code: 4

5 Primary interactions Recently implemented DIS via PYTHIA code All channels: Necessary for flux averaging 5

6 Input: QE, RES, 1-pion bgr, DIS QE,RES: Hadronic current parametrized in terms of form factors Vector form factors: related to el-m for factors by CVC BBBA2007 parameterization for QE, MAID parameterization for RES (MAID, Drechsel EPJA 34: Mainz unitary isobar model for pion photo- and electroproduction on the nucleon; it provides the resonance helicity amplitudes, from which el-m transition form factors are derived) Axial form factors dipole ansatz, related via Partial Conservation of the Axial Current MA=1 GeV for QE using neutrino-proton data when possible 1-pion background: Pure phenomenological, fitted to MAID results DIS: PYTHIA code see Leitner PRC73 for detailes 6

7 Isoscalar cross section Calculations are done with default GiBUU parameters, no fine tuning Correction for non-isoscalarity ~ 4% 7

8 Steps in the GiBUU code 1. Initialize nucleus local density approximation with realistic density profile density + momentum-dependent meanfield potential local Thomas-Fermi gas model Density ( ), Fermi momentum (pf), mean-field potential (VN) and Fermi energy ( F) of protons as functions of nucleon radius Distributions are correlated Low momentum nucleons tend to sit at low densities 8

9 Steps in the GiBUU code 2. Calculate in-medium cross section vacuum form factors for QE and RES production broadening of the resonances (collisional or Oset/Salsedo) in-medium modified cross section full in-medium kinematics Pauli blocking Benchmark: electroproduction, medium effects in double-diff xsec typical result: Medium inclusive cross section for QE and Delta suppressed 9

10 ? Medium DIS cross section? PYTHIA code calculates free DIS cross section We should some how remove (or no not remove) in-medium potential in order to provide the input kinematics for PYTHIA No unique prescription how to do this. Several possibilities: F-NO F-CM F-THRE No difference between them for electroproduction Neutrinos: Difference between them is the intrinsic uncertainty of the GiBUU 10

11 Medium DIS cross section GiBUU uncertainty in DIS nuclear effects ~ 4% neutrino antineutrino 11

12 Medium W - distributions 12

13 Steps in the GiBUU code 3. Propagate outgoing particles through nucleus according to Boltzmann-Uehling-Uhlenbeck equation 61 baryons and 21 mesons coupled through the collison integral; decay of unstable particles elastic and inelastic 2- and 3- body scattering Pauli blocking for fermions result: spectra of the outgoing particles with and without FSI are different 13

14 Pions: Primary interactions (before Final State Interactions): Main mechanism at low energies: N N Also from higher mass baryon resonances DIS at high energies Final State Interactions: Outgoing pions/nucleons/resonances can rescatter N N, N, N, N NN NR, NR' NR with R decaying to pions Thus possibility of QE contribution n p through FSI : main mechanism NN N Pion can be absorbed NN N N, N, K, K, KKN 14

15 Misidentification of the events Why understanding of FSI is so important? Pion production misidentified as quasi-elastic event Neutral current 0 production as background to e- appearance Cherenkov rings are very similar Background: N 0 N Effect: e n e- p 15

16 Benchmark for Final State Interactions Photoproduction: Krusche, Lehr, EPJA 22 (2004) 16

17 Miner a: Pions: with and w/o FSI MINOS flux Low Energy E > 1.5 GeV 1-pion = 1 pion of a given charge and no other pions 17

18 Pions: channels 1X= 1 pion of a given charge and any number of other pions 2X= 2 pions of a given charge and any number of other pions MULTI pion = at least 1 pion of a given charge and any number of other pions 18

19 Pions: origin MINOS flux E > 1.5 GeV 19

20 Kaons: Primary interactions (before Final State Interactions): Kaon production in low-energy region not implemented (minor effect) Kaons only from DIS Final State Interactions: Outgoing pions/nucleons/resonances can rescatter N K, K, KKN NN N K, N K NN NR, NR' NR with R decaying to kaons Kaons can rescatter KN KN,, 20

21 Charged kaons: with and w/o FSI 21

22 Neutral kaons: with and w/o FSI 22

23 Conclusions GiBUU is a multi-purpose model to describe final state interactions With DIS recently implemented in the GiBUU code, calculations for high energy neutrino scattering are possible Preliminary estimate of the nuclear effects uncertainty 4-5% Predictions for MINOS and Miner a experiments: energy distributions of various outgoing particles 23