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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
Modeling of Neutrino Oscillations
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3 - flavor oscillations
One dominant mass scale approximation
Switching matter effects ON/OFF
In this framework, the vμ survival
probability, for example, is
Example: Δm232=0.004 eV2/c4 θ23=45ο, θ13=11.5ο
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.
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
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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:
Single Pion Production
Baryonic 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 ReinSeghal were modified by
assuming non-interference
between different resonances
Single Pion Production Predictions & Comparisons
with data
Neutrino Interactions - Deep Inelastic Scattering
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We use the parameterization of E.A.Pashos and J.Y.Yu, “Neutrino
Interactions in Oscillation Experiments”, hep-ph/0107261
Parton Density Functions
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We use the MRST99 parton
density function set
MRST99 is described in hepph/9907231 (A.D. Martin,
R.G. Roberts, W.J. Stirling,
R.S. Thorne)
The ‘evolution’ stops at
Q2min=1.25GeV2. For
Q2<Q2min we consider pdfs to
be the same as for Q2=Q2min
DIS - Predictions & Comparisons with data
All modeled Neutrino Interaction Processes