Update on Data / MC Comparisons for Low Hadronic Energy CC-like Events Reminder of problem Fiducial studies with more MC statistics Effect of offset in MC hadronic energy scale Effect of smearing MC muon angles Further studies ND Parallel Session (10 th Sept.) MINOS Collaboration Meeting Mark Dorman UCL / RAL

Reminder of Problem When a low hadronic energy CC-like sample is selected there are large excesses of events in data as compared to MC. There is also a shift to higher muon angles with respect to the neutrino direction in the data.

More on Angular Discrepancy 'Safe DIS' Low Q^2 DIS QEL/Delta Transition

Fiducial Studies Revisited 'Anulii'

Fiducial Studies Revisited 'Halves 1'

Fiducial Studies Revisited 'Halves 2'

Fiducial Studies Revisited 'z Regions'

Effect of Constant Offset in Hadronic Shower Energy As suggested by Debbie have now considered an offset in the hadronic shower energy in MC (previously considered a scaling factor). Crude way to consider 'intranuke' effects – can change things greatly.

Effect of Constant Offset in Hadronic Shower Energy Doesn't directly change the muon angle distribution but affects the low hadronic energy sample that is selected. Reducing the hadronic energy helps data/MC agreement but does not shift the MC to higher angles.

Effect of Smearing MC Muon Angle Distribution Sampled from 1-sided Gaussian distribution centered at zero and with various sigma and added these values to the muon angles. As such am only considering and increase in the opening angle between muon and neutrino direction. Can get better peak agreement with an offset of -100 MeV and smearing by Gaussian with sigma = 0.02 radians (~1.15 degrees).

Conclusions and Further Work No obvious systematic effect coming from fiducial studies. Changes in the hadronic energy in MC can have a big effect on the low hadronic energy CC-like samples. Am eagerly awaiting Daikon MC and new implementation of intranuke to make MC/MC comparisons. Am currently generating PANs for Cedar reconstruction release. Cedar has a new tracker and in particular contains changes to the way tracks are extrapolated through the shower – this could have an impact on the muon angle distributions. Depending on the results of the above could do some hand scanning. Want to consider other instrumental effects. Could look at events by timing in spill or by intensity. Could the low PH noise removal be having an effect for these low shower energy events?

Backup Slides

Cuts and Reweighting Pre-selection cuts differ (slightly) from standard CC analysis: Data must pass standard beam quality cuts and the special horn current runs are excluded. CC-like events are then selected with CC PID > The label 'tuned MC' refers to MC that has been weighted using the 12 parameter SKZP2 beam and hadron production weights and the MODBYRS3 generator weights. Event has 1 well reconstructed track and is in the 'Pittsburgh' fiducial volume If muon momentum is measured from curvature then the fractional error on this measurement is not more than 30% Zero or negative muon charge sign (anti-neutrino cut) Track starts at least 0.5m inside the detector (rock muon cut) Either there is no event within 50ns of the current event or the current event has at least 95% of the PH of itself and the nearest event (runt event cut)

More on Muon Angles Whole Kinematic Plane

More on Muon Angles 'Safe' DIS (W^2 > 4, Q^2 > 1)

More on Muon Angles Low Q^2 DIS (W^2 > 4, Q^2 < 1)

More on Muon Angles QEL / Delta (W^2 < 1.69)

More on Muon Angles Transition (1.69 < W^2 < 4)