mc generator for neutrino interaction experiments authors: costas andreopoulos, panos stamoulis,...
TRANSCRIPT
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