MC GEnerator for Neutrino Interaction Experiments

Authors: Costas Andreopoulos, Panos Stamoulis, George Tzanakos

• Object-Oriented Design• Extensive use of Design Patterns & Reusable Software Architectures• Extensive use of ROOT & STL• Extensive use of XML• Network (TCP/IP) Interfaces• Modeling of all neutrino interaction processes, calculation of cross sections, form factors, parton densities...• Modeling of auxiliary phenomena : 3-D neutrino oscillations, matter effects, muon energy loss mechanisms...

GENIE is in prototyping-phaseThis work was based on Prototype Version 1Version 2 will be on public domain (distributed under GPL) this summer

• 3 - flavor oscillations

• One dominant mass scale approximation

• Switching matter effects ON/OFF

Modeling of Neutrino Oscillations

In this framework, the vμ survival probability, for example, is

Example: Δm232=0.004 eV2/c4 θ23=45ο, θ13=11.5ο

• Quasi Elastic Scattering : Simple! The neutrino sees a “structureless” target nucleon.

• Single Pion Production : Complex! Need a dynamical model to describe

the bound state of quarks.• Deep Inelastic Scattering : Simple again! The neutrino sees the nucleon

structure but scatters off a structureless parton.

Neutrino Interactions

Include:Quasi Elastic ScatteringSingle Pion ProductionDeep Inelastic Scattering

Leptonic tensor: well known from V-A theory

Hadronic tensor?

Neutrino Interactions - Quasi Elastic Scattering

We use the parameterization of E.A.Pashos and J.Y.Yu, “Neutrino Interactions in Oscillation Experiments”, hep-ph/0107261

CC QE Form Factors

Kinematic Limits

Quasi Elastic Scattering - Predictions & Comparisons with data

Neutrino Interactions - Single Pion Production

• We use the model of Deiter Rein and Lalit M. Seghal, “Neutrino - Excitation of Baryon Resonances and Single Pion Production”, Ann. Phys, 133, 79 (1981)

• This model is based on the dynamical model of baryon excitation of R.P. Feynman, M. Kislinger and F. Ravndal, Phys. Rev. D 3, 2706 (1971)

Kinematical Limits

q2: same as in QE (MNMRES)

W:

Helicity components

Single Pion ProductionBaryonic Resonances

• Taking into account 16 resonances• Single Pion Production is dominated by Δ(1232)P33

Each resonance is described by a Breit-Wigner distribution with an L-dependent threshold behavior

Single Pion Production Isospin Analysis

• Cross Sections for different channels are built from cross sections for exciting baryon

resonances

•Using isospin Glebsch-Gordon coefficients

• Original expressions by Rein-Seghal were modified by

assuming non-interference between different resonances

Single Pion Production - Predictions & Comparisons

with data

• We use the parameterization of E.A.Pashos and J.Y.Yu, “Neutrino Interactions in Oscillation Experiments”, hep-ph/0107261

Neutrino Interactions - Deep Inelastic Scattering

Parton Density Functions

• We use the MRST99 parton density function set

• MRST99 is described in hep-ph/9907231 (A.D. Martin, R.G. Roberts, W.J. Stirling, R.S. Thorne)

• The ‘evolution’ stops at Q2

min=1.25GeV2. For Q2<Q2min

we consider pdfs to be the same as for Q2=Q2

min

DIS - Predictions & Comparisons with data

All modeled Neutrino Interaction Processes