Charged Current Coherent Pion Production in MINERνA Aaron Mislivec University of Rochester w/ Aaron Higuera Outline • Motivation • MINERνA Detector and Kinematics Reconstruction • Event Selection • Background Tuning • Contribution from Diffractive Scattering off Hydrogen • Systematics • Cross Sections Aaron Mislivec, University of Rochester NuInt14 2 K. HIRAIDE et al. PHYSICAL REVIEW D 78, 112004 (2008) 100 TABLE III. Event selection summary for the MRD-stopped DATA charged current coherent pion sample. CC coherent π Event selection Data MC Coherent % CC resonant π Signal BG Efficiency Other Generated in SciBar fid.vol. 1939 156 766 100% CC QE 50 SciBar-MRD matched 30 337 978 29 359 50.4% MRD-stopped 21 762 715 20 437 36.9% two-track 5939 358 6073 18.5% Entries / 5 degrees Particle ID (" %) 2255 292 2336 15.1% Vertex activityþ cut 887 264 961 13.6% CCQE rejection 682 241 709 12.4% 0 0 20 40 60 80 100 120 140 160 180 Pion track direction cut 425 233 451 12.0% Reconstructed Q2 cut 247 201 228 10.4% ∆θp (degrees) FIG. 11 (color online). Á for the " % events in the MRD p þ stopped sample after fitting. which the track angle of the pion candidate with respect to the beam direction is less than 90 degrees are selected. Figure 13 shows the reconstructed Q2 distribution for the " % events after the pion track direction cut. Althoughþ a charged current quasielastic interaction is as- DATA 80 sumed, the Q2 of charged current coherent pion events is CC coherent π reconstructed with a resolution of 0:016 GeV=c 2 and a CC resonant π 2 ð Þ 60 shift of 0:024 GeV=c according to the MC simulation. Other Finally,À eventsð withÞ reconstructed Q2 less than CC QE 0:1 GeV=c 2 are selected. The charged current coherent 40 pionð eventÞ selection is summarized in Table III. In the Volume 313, number 1,2 PHYSICS LETTERS B 26 August 1993 signal region, 247 charged current coherent pion candi- Entries / 5 degrees 300 ' '' 'I '~ ' 'I ' ' ''I'~ 300 -I I I I I I I I I I I I I I I I dates are observed, while the expected number of back- 20 250 250 ground events is 228 12. The error comes from the errors B&K Æ oE 200 •Eo200 on the fitting parameters summarized in Table II. The ~b 150 ~-~" 150 0 background in the final sample is dominated by charged % 020406080100120140160180 .-~ 100 13~ 100 Pion track angle (degrees) current resonant pion production. The ‘‘other’’ background 50 Z Need5O for New Data on is comprised of 50% charged current DIS, 32% neutral , i i I i i i i I i i i I I i i i i l i i i i I i i i I I i 0 50 100 150 0 50 100 150 FIG. 12 (color online). Track angle of the pion candidate with current, and 18% #" events. The selection efficiency for Ev [GeV] E ~ [ GeV] respect to the beam direction for the " % events after the þ the signal is estimated to be 10.4%. Fig. 5. Visible cross section (En >/ 5 GeV) for coherent single charged plon production for neutrino and antmeutrmocharged induced current quasielastic rejection after fitting. interactions. The predictionsCC of the Rein-Sehgal modelCoherent (full hne) and of the Bel'kov-Kopehovlch model (dashed Pion hne) are Production indicated Phys. Lett. B 313, 267 (1993) Phys. Rev. D 78, 112004 (2008) 500 i i i I i i i I i 'i' ' ' ' i i i i i i i i i , i s i 40 400 150 E SciBooNE o 300 o DATA .?, DATA 2 2 ~ 200 30 CC coherent • penment) CC coherent π .I ~ TI x Aachen ~Padua [1] +Gargamelle[2] π 100 4~"t' " • CHARM.L3].. • SKAT (CC) [4] CC resonant π ./~ ¢, SKAT (NC) [4] • BEBC[7] 100 CC resonant π ,, I , , I,,, I ,O,F~A~-[~],, I, ,qF~/~LI9], I , 20 40 60 80 100 120 140 Other Other Ev [GeV] 20 CC QE CC QE 500 I i I I I I I I ill II I II I lli I I I ill I 400 ~_ 12 -12 + 50 νμ C→μ Cπ 10 Entries / 0.025 (GeV/c) 300 i Entries / 0.025 (GeV/c) ~ : <Eν>=1.1GeV b 200 J,)~LJT/"1~. ' .L ~dua [1] + Gargamelle [2] 100 • CHARM [3] T 0 i , I i i i I M t , I R M , I r , , I i m r I i i i I i 0 0 20 40 60 80 100 120 140 0 0.1 0.2 0.3 0.4 0.5 0 0.1 0.2 0.3 0.4 0.5 E~ [GeV] Q2 (GeV/c)2 Q2 (GeV/c)2 Fig. 6. Compilation of experiments on coherent single p]on producUon. Shown are the results from both neutral current [ 1-4] and charged current [4-9] data, for neutrino and antmeutrmo reduced interactions. The FNAL [8,9 ] values from combined neutrino and antmeutrmo data have been included m the upper dxagram For this experiment theFIG. results for 13 the (color online). Reconstructed Q2 for the " % events FIG. 14 (color online). Reconstructed Q2 for the " % events visibleOlder cross section data were corrected of chargedfor the selecUon ofcurrent En >/ 5 GeV according(CC) to thecoherent Bel'kov-Kopellov~ch pion approach. production Data at higher energy (Eν > ~10 GeV)þ agrees þ • from other experiments have been scaled, where necessary, to allow comparison The pred]cuons of the Rem-Sehgalin the model MRD stopped sample after the pion track direction cut and in the MRD penetrated sample after the pion track direction cut (full hne)with and ofthe the Bel'kov-Kopeliovlch Rein-Sehgal model model(dashed hne) areprediction mdxcated. after fitting. after fitting. 274 • K2K and SciBooNE data at Eν < 2 GeV is consistent with no CC coherent pion production and places an upper limit on the production rate that is significantly lower than the Rein-Sehgal model prediction 112004-14 • Limitations of the Rein-Sehgal model have been discussed in-depth at NuInt • Constraining CC coherent pion production at 1-5 GeV is needed by oscillation experiments Aaron Mislivec, University of Rochester NuInt14 3 Enter MINERνA • We are measuring neutrino and antineutrino CC coherent pion production on Carbon for 1.5 GeV < Eν < 20 GeV • This analysis uses the GENIE v2.6.2 event generator, which uses the Rein-Sehgal model for CC coherent pion production with lepton mass corrections Our signal definition: • • a positively identified muon and pion • a quiet event vertex (i.e. no nuclear break-up) 2 • low |t| = |(q-pπ) | • model independent, unambiguous signature of coherent scattering • MINERνA is the first contemporary experiment measuring |t| event-by-event Aaron Mislivec, University of Rochester NuInt14 4 The MINERνA Detector Elevation View Side HCAL μ Side ECAL ν-Beam π O) Active Tracker 0.25t 2 ! From NuMI Region H 2.14 m 3.45 m Hadronic Hadronic Steel Shield Steel Calorimeter Liquid 8.3 tons total Calorimeter Nuclear Target Electromagnetic Helium Region (C, Pb, Fe, FiducialFiducial Region Region Scintillator Veto Wall Veto Scintillator 15 tons 30 tons (Muon Spectrometer) Side ECAL 0.6 tons Detector Near MINOS Side HCAL 116 tons 5 m 2 m • We analyze events in our fully active central scintillator (C-H) tracker region - fine-grained for measuring μ and π direction 1 • Reconstructing the μ in both MINERνA and MINOS gives a measurement of pμ and muon charge • The downstream and side calorimeters provide containment of the π for measuring Eπ 2 • MINERνA has full access to the μ and π kinematics for measuring |t| = |(q-pπ) | Aaron Mislivec, University of Rochester NuInt14 5 νμ CC Coherent Pion Production Candidate in MINERνA Data Run 2019/5/339/1 Eν = 6.53 GeV Eπ = 2.37 GeV |t| = 0.001 (GeV/c)2 Aaron Mislivec, University of Rochester NuInt14 6 Kinematics Reconstruction 200 mm Vertex Exclusion Region • We accurately measure pμ for muons reconstructed in both MINERνA & MINOS • Since most pions interact in our detector, Eπ reconstructed as: • total non-muon calorimetric energy > 200 mm from event vertex • +60 MeV estimate of single pion calorimetric energy within 200 mm from event vertex • Excluding the vertex region minimizes sensitivity to mis-modeling vertex activity in background events • Eν = Eμ + Eπ (assumes zero energy transfer to nucleus) • Assume neutrino direction is parallel to beam axis 2 2 • |t| = |(q - pπ) | = |(pν - pμ - pπ) | Aaron Mislivec, University of Rochester NuInt14 7 Event Selection: CC 2-Particle Sample • Muon originates in the tracker region • Muon is reconstructed in both MINERνA & MINOS • Muon charge is negative for neutrinos, positive for antineutrinos • Exactly one reconstructed hadron at the event vertex Aaron Mislivec, University of Rochester NuInt14 8 Event Selection: Proton Veto - + + - 3 i + A A A + µ + / 3 i + A A A + µ + / ×10 µ ×10 µ 18 MINERiA Preliminary Data MINERiA Preliminary Data POT Normalized 3.5 POT Normalized 16 2.15e+20 POT Coh Pion 1.06e+20 POT Coh Pion Events Events 3 14 Pion Pion 12 Proton 2.5 Proton Other Other 10 2 8 Cuts: 1.5 6 CC 2-Particle Sample 1 4 2 0.5 0 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Proton Score Proton Score • Events with a reconstructed proton, particularly CCQE, are important backgrounds for the neutrino analysis • Above is the proton likelihood of the reconstructed hadron from fitting the energy deposition along its reconstructed path • To reject events with a reconstructed proton, the neutrino analysis requires the proton score be < 0.35 • The antineutrino analysis does not cut on this variable since events with a reconstructed proton are rejected by cuts on vertex energy and |t| Aaron Mislivec, University of Rochester NuInt14 9 Event Selection: Vertex Energy - + + - 3 i + A A A + µ + / 3 i + A A A + µ + / ×10 µ ×10 µ MINERiA Preliminary DATA 1.6 MINERiA Preliminary DATA POT Normalized POT Normalized 6 2.15e+20 POT COH 1.06e+20 POT COH QE 1.4 QE 5 RES W<1.4 1.2 RES W<1.4 1.4<W<2.0 1.4<W<2.0 W> 2.0 1 W> 2.0 4 Other Other Cuts: Events / 10 MeV Events / 10 MeV 0.8 CC 2-Particle Sample 3 Proton Veto (νμ) 0.6 2 0.4 1 0.2 0 0 0 50 100 150 200 250 300 0 50 100 150 200 250 300 Vertex Energy (MeV) Vertex Energy (MeV) • No nuclear break-up occurs