Native GENIE splines with Cooper-Sarkar-Mertsch-Sarkar (CSMS) neutrino cross-sections for high energy neutrino deep inelastic scattering (DIS) interactions.
The largest source of uncertainties in calculating neutrino cross-sections at high energies is the uncertainties on the parton distribution functions (PDFs) of the nucleon.
CSMS neutrino cross-section is an updated prediction of high energy neutrino and anti-neutrino charged current (CC) and neutral current (NC) DIS cross-sections using the Dokshitzer–Gribov–Lipatov–Altarelli–Parisi (DGLAP) formalism of next-to-leading-order (NLO) Quantum Chromodynamics (QCD) and using the HERAPDF1.5 PDF fits.
This modified GENIE neutrino cross-section spline package attempts to incorporate the CSMS DIS neutrino cross-sections into the native GENIE neutrino cross-section splines.
This neutrino cross-section spline package is designed such that the user can just download the spline package, specify this spline package .xml file to be used using the --cross-sections flag while generating events in GENIE, and GENIE will generate the neutrino events according to:
- Native GENIE neutrino cross-section for neutrino energies below 70 GeV
- A mixture of native GENIE neutrino cross-section and CSMS cross-section in the transition region from 70-200 GeV
- Pure CSMS cross-sections from 200-1000 GeV. CSMS cross-section for neutrino energies above 1000 GeV is not included in this spline package, but can be included should there be a demand for it.
The total charged current cross-section as a function of incoming neutrino energy for the various neutrino flavours on Hydrogen-1 and Oxygen-16 is show in the figure below:
Zooming in to the transition and CSMS region, the modified GENIE cross-section deviates from the CSMS cross-section values by <10% at the 70 GeV and dropping down to <2% in the pure CSMS region:
The full collection of plots showing native GENIE cross-sections overlaid with CSMS cross-sections can be found in: https://github.com/plt109/csms_genie/tree/master/figures/xsec
The native GENIE cross-section that this work is based on is obtained using the following command in GENIE 2.8.6:
gmkspl -p 12,-12,14,-14,16,-16 -t 1000080160,1000010010 -e 1000 -o 'native_genie.xml' -n 500
In the transition region from 70-200 GeV, the native GENIE neutrino cross-section tapers off linearly while the CSMS cross-section is introduced linearly. This treatment minimises ripples in cross-section splines when GENIE interpolates from the cross-section splines using cubic splining.
CSMS neutrino cross-sections are calculated for Q^2>1GeV^2 so that perturbative QCD methods can be reliably used. CSMS neutrino cross-section values are not only available for neutrino energies <50 GeV as this region would have contributions from Q^2<1GeV^2. Details of the CSMS cross-sections calculations can be found at: https://arxiv.org/abs/1106.3723v2
Comparing native GENIE cross-sections, CSMS cross-sections with total inclusive CC isoscalar cross-section measurements from
νμN → μ−X for the PDG cross section (G.P. Zeller June 2012). Visually, 200 GeV looks like a stable spot for native GENIE cross-section to transit into CSMS cross-sections fully.
Left the tau neutrino cross-sections untouched because the tau neutrino cross section is different from that of the muon neutrino cross section (Refer to Fig. 2 of https://arxiv.org/pdf/1007.1966.pdf) while the CSMS neutrino cross section is the same for electron neutrinos, muon neutrinos and tau neutrinos.
GENIE will use the following event generators when the list of event generators to be used is not specified:
- Charged current quasi-elastic scattering (QEL-CC)
- Neutral current quasi-elastic scattering (QEL-NC)
- Charged current baryon resonance production (RES-CC)
- Neutral current baryon resonance production (RES-NC)
- Charged current deep inelastic scattering (DIS-CC) *
- Neutral current deep inelastic scattering (DIS-NC) *
- Charged current coherent neutrino-nucleus scattering (COH-CC)
- Neutral current coherent neutrino-nucleus scattering (COH-NC)
- Charged current deep inelastic charm production (DIS-CC-CHARM) *
- Charged current deep quasi-elastic charm production (QEL-CC-CHARM)
- Neutrino-electron elastic scattering (NUE-EL)
- Inverse muon decay (IMD)
- Inverse muon decay (IMD-ANH)
Cross-sections of only the channels marked with an asterisk(*) are modified in this cross-section spline package.
This set of GENIE with CSMS cross-section splines was developed and tested with GENIE 2.8.6. on Red Hat Linux.
Download GENIE splines with CSMS cross-section found at https://github.com/plt109/csms_genie/blob/master/full_package_conjoined_v9b.tar.gz
Extract the .tar.gz file to your desired path(e.g. /path_to_GENIE/GENIE_2_8_6/data/xsec/).
tar -zxvf full_package_conjoined_v9b.tar.gz -C /path_to_GENIE/GENIE_2_8_6/data/xsec/
full_package_conjoined_v9b.tar.gz contains the following files:
- Read me description file: README.txt
- Cross-section XML spline file: full_package_conjoined_v9b.xml (MD5 = df86ee7afdef52e02ad591618332edc5)
This cross-section XML spline file must be specified when generating events using GENIE.
To generate 5000 events in each of which a 300 GeV muon neutrino interacts with water(88.79% O16, 11.21% H1):
gevgen -n 5000 -e 300 -p 14 --cross-sections /path_to_spline/full_package_conjoined_v9b.xml -t 1000080160[0.8879],1000010010[0.1121]
Checking the distribution of multiplicities of the stable daughter particles
Checking the distribution of the 4-momentum components of the stable daughter particles
The full collection of the cross-check plots can be found in: https://github.com/plt109/csms_genie/tree/master/figures
Pueh Leng Tan, 5 February 2019