GENIE

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GENIE
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-phase This work was based
on Prototype Version 1 Version 2 will be on
public domain (distributed under GPL) this summer
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Modeling of Neutrino Oscillations

• 3 - flavor oscillations
• One dominant mass scale approximation
• Switching matter effects ON/OFF

In this framework, the vµ survival probability,
for example, is
Example ?m2320.004 eV2/c4 ?2345?, ?1311.5?
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Neutrino Interactions
Include Quasi Elastic Scattering Single Pion
Production Deep Inelastic Scattering
Leptonic tensor well known from V-A theory
Hadronic tensor?

• 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.

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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
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Quasi Elastic Scattering - Predictions
Comparisons with data
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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)

Helicity components
Kinematical Limits
q2 same as in QE (MN?MRES)
W
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Single Pion ProductionBaryonic Resonances

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

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

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Single Pion Production - Predictions
Comparisons with data
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Neutrino Interactions - Deep Inelastic Scattering

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

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 Q2min1.25GeV2. For
  Q2ltQ2min we consider pdfs to be the same as for
  Q2Q2min

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DIS - Predictions Comparisons with data
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All modeled Neutrino Interaction Processes