No Arabic abstract
The cross section of neutrino-induced neutral-current coherent $pi^0$ production on a carbon-dominated target is measured in the NOvA near detector. This measurement uses a narrow-band neutrino beam with an average neutrino energy of 2.7,GeV, which is of interest to ongoing and future long-baseline neutrino oscillation experiments. The measured, flux-averaged cross section is $sigma = 13.8pm0.9 (text{stat})pm2.3 (text{syst}) times 10^{-40},text{cm}^2/text{nucleus}$, consistent with model prediction. This result is the most precise measurement of neutral-current coherent $pi^0$ production in the few-GeV neutrino energy region.
Forward single $pi^0$ production by coherent neutral-current interactions, $ u mathcal{A} to u mathcal{A} pi^0$, is investigated using a 2.8$times 10^{20}$ protons-on-target exposure of the MINOS Near Detector. For single-shower topologies, the event distribution in production angle exhibits a clear excess above the estimated background at very forward angles for visible energy in the range~1-8 GeV. Cross sections are obtained for the detector medium comprised of 80% iron and 20% carbon nuclei with $langle mathcal{A} rangle = 48$, the highest-$langle mathcal{A} rangle$ target used to date in the study of this coherent reaction. The total cross section for coherent neutral-current single-$pi^0$ production initiated by the $ u_mu$ flux of the NuMI low-energy beam with mean (mode) $E_{ u}$ of 4.9 GeV (3.0 GeV), is $77.6pm5.0,(text{stat}) ^{+15.0}_{-16.8},(text{syst})times10^{-40},text{cm}^2~text{per nucleus}$. The results are in good agreement with predictions of the Berger-Sehgal model.
The single $pi^0$ production rate in neutral current neutrino interactions on water in a neutrino beam with a peak neutrino energy of 0.6 GeV has been measured using the P{O}D, one of the subdetectors of the T2K near detector. The production rate was measured for data taking periods when the P{O}D contained water ($2.64times{}10^{20}$ protons-on-target) and also periods without water ($3.49 times 10^{20}$ protons-on-target). A measurement of the neutral current single $pi^0$ production rate on water is made using appropriate subtraction of the production rate with water in from the rate with water out of the target region. The subtraction analysis yields 106 $pm$ 41 (stat.) $pm$ 69 (sys.) signal events, which is consistent with the prediction of 157 events from the nominal simulation. The measured to expected ratio is 0.68 $pm$ 0.26 (stat.) $pm$ 0.44 (sys.) $pm$ 0.12 (flux). The nominal simulation uses a flux integrated cross section of $7.63times{}10^{-39}$ cm${}^2$ per nucleon with an average neutrino interaction energy of 1.3 GeV.
The ArgoNeuT collaboration reports the first measurement of neutral current $pi^{0}$ production in $ u_{mu}$-argon and $bar{ u}_{mu}$-argon scattering. This measurement was performed using the ArgoNeuT liquid argon time projection chamber deployed at Fermilabs NuMI neutrino beam with an exposure corresponding to 1.2$times 10^{20}$ protons-on-target from the Fermilab Main Injector and a mean energy for $ u_{mu}$ of 9.6~GeV and for $bar{ u}_{mu}$ of 3.6~GeV. We compare the measured cross section and kinematic distributions to predictions from the GENIE and NuWro neutrino interaction event generators.
The SciBooNE Collaboration reports a measurement of neutral current coherent neutral pion production on carbon by a muon neutrino beam with average energy 0.8 GeV. The separation of coherent from inclusive neutral pion production has been improved by detecting recoil protons from resonant neutral pion production. We measure the ratio of the neutral current coherent neutral pion production to total charged current cross sections to be (1.16 +/- 0.24) x 10-2. The ratio of charged current coherent pion to neutral current coherent pion production is calculated to be 0.14+0.30 -0.28, using our published charged current coherent pion measurement.
Neutrino neutral-current induced single photon production is a sub-leading order process for accelerator-based neutrino beam experiments including T2K. It is, however, an important process to understand because it is a background for electron (anti)neutrino appearance oscillation experiments. Here, we performed the first search of this process below 1 GeV using the fine-grained detector at the T2K ND280 off-axis near detector. By reconstructing single photon kinematics from electron-positron pairs, we achieved 95% pure gamma ray sample from 5.738$times 10^{20}$ protons-on-targets neutrino mode data. We do not find positive evidence of neutral current induced single photon production in this sample. We set the model-dependent upper limit on the cross-section for this process, at 0.114$times 10^{-38}$ cm$^2$ (90% C.L.) per nucleon, using the J-PARC off-axis neutrino beam with an average energy of $left<E_ uright>sim 0.6$ GeV. This is the first limit on this process below 1 GeV which is important for current and future oscillation experiments looking for electron neutrino appearance oscillation signals.