1 / 39

Neutrino Interactions with Nucleons and Nuclei

Neutrino Interactions with Nucleons and Nuclei. Tina Leitner, Oliver Buss , Ulrich Mosel, Luis Alvarez- Ruso. TexPoint fonts used in EMF. Read the TexPoint manual before you delete this box.: A A A A A A A A A A A. Soudan Mine, Nova. 770 km. Homestake Mine Dusel. 1300 km.

clem
Download Presentation

Neutrino Interactions with Nucleons and Nuclei

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Neutrino InteractionswithNucleonsandNuclei Tina Leitner, Oliver Buss, Ulrich Mosel, Luis Alvarez-Ruso Beijing 03/10 TexPoint fonts used in EMF. Read the TexPoint manual before you delete this box.: AAAAAAAAAAA

  2. Soudan Mine, Nova 770 km Homestake Mine Dusel 1300 km Beijing 03/10

  3. Long baselineexperiments M. Wascko Beijing 03/10

  4. Neutrino oscillationsearch • neutrinooscillations: probabilityfor 2 flavors: • Crucialparameter: neutrinoenergyE Need to understand ‚classical‘ hadronicinteractions Flux: obtained from Event-Generators for hadronic production and subsequentweak decay Energy must be reconstructed from hadronic final state Beijing 03/10

  5. Oscillation Minium atMiniBooNE Beijing 03/10

  6. Motivation Beijing 03/10 • Neutrino detectorsnowadays all contain (heavy) nuclei, haveto understand interactionsofneutrinoswith matter • Interactions ofneutrinoswithnucleimaymaketheidentificationofelementaryprocesses, like knock-out, pion-productionorqescatteringdifficult.

  7. Motivation Beijing 03/10 • In-medium physics: vectorand axial form factors in medium havetobeextractedfromreactions on nuclei. • NUTEV anomalyfor Weinberg angle • Axial Mass: in MiniBooNEand K2K: 1.0 or 1.25 GeV? • Neutrino-energy must bereconstructedfromdetectorresponse. NuclearPhysics Input isneeded

  8. The Rebirth of Low Energy Nuclear Physics Low-Energy Nuclear Physics determines response of nuclei to neutrinos Beijing 03/10

  9. Outline l n W, Z • neutrino-nucleusreaction: nlA l hadronsat ~ 0.5 – 1.5 GeVneutrinoenergy • scattering off a singlenucleon • freenucleon • nucleonbound in a nucleus • Total QE scattering off a nucleusandproduction • final state interactions (FSI) • GiBUUtransport model • Results:qe scattering,p production, nucleon knockout • Conclusions Beijing 03/10

  10. Model Ingredients: ISI Beijing 03/10 • Free primary interaction cross sections, cross sections boosted to restframe of moving nucleon in local Fermigas • no off-shell dependence, but include spectral functions for baryons and mesons (binding + collision broadening) • Cross sections taken from • Electro- and Photoproduction for vector couplings • Axial couplings modeled with PCAC • Pauli-principle included • Shadowing by geometrical factor (Q2,) included

  11. Potential smoothes E-p distributions Model Ingredients: ISI • Hole spectralfunction (local TF)Local Thomas-Fermi Particles in mean-field potential! • Particlespectralfunction: collisionalbroadening • Inclusivecrosssection Beijing 03/10

  12. Neutrino nucleoncrosssection QE single ¼ R+ ‚ DIS ¼ N N' note: 10-38 cm² = 10-11 mb P. Lipari, Nucl. Phys. Proc. Suppl. 112, 274 (2002) Beijing 03/10

  13. Quasielasticscattering • reactions: • hadronic current: with • axial form factors • related by PCAC • dipole ansatz • extra term • ensures vector current conservationfor nonequal masses • vector form factors • related to EM form factors by CVC • BBBA-2007 parametrization in addition: strange vector and axial form factors for NC Beijing 03/10

  14. Quasielasticscattering Beijing 03/10

  15. QuasielasticScattering: Axial Mass • neutrinos probe nucleons / nuclei via V-A weak interaction • axial structureof the nucleon and baryonic resonances (in the medium!) • nuclear effects(e.g. low-Q² deficit in MiniBooNE) • dedicated neutrino-nucleus experiment: Minerva Beijing 03/10

  16. Pion productionthroughresonanceexcitation • 13 resonanceswith W < 2 GeV • pionproductiondominatedbyP33(1232) resonance: • CVfromelectrondata (MAID analysiswith CVC) • CAfrom fit toneutrinodata(experiments on hydrogen/deuterium) BNL 10 % error in C5A(0) ANL discrepancy between ANL and BNL data  uncertainty in axial form factor Beijing 03/10

  17. CC pionproduction on freenucleons • CC productionofD+andD++ • subsequent decayinto3channels: BNL data including higher resonances (isospin ½): ANL data How much is background?? Beijing 03/10

  18. Pion productionthrough¢ New V, old A New V, new A averagedover ANL flux, W < 1.4 GeV Beijing 03/10

  19. Nuclear Targets (K2K, MiniBooNE, T2K, MINOS, Minerva, …. Beijing 03/10

  20. Medium modifications of the inclusive cross section • All crosssections Fermi smeared • D crosssectionisfurthermodified in thenuclear medium: • p decaymightbe Pauli blocked: decreaseofthefreewidth • additional "decay" channels in the medium: collisionalwidthcoll overalleffect: increaseofthewidth !med = P + coll collisional broadening "pion-lessdecay" Beijing 03/10

  21. Model validation: electronscattering PRC 79, 034601 (2009) Beijing 03/10

  22. Transport vs. Quantummechanics Beijing 03/10 • Fullyinclusivereactions: noinfo on final states, both • Quantum-mechanicalreactiontheory (Relativistic Impuls Approximation RIA, Distorted Wave Impuls Approximation DWIA) • Transport theory Bothapplicable, leadto same results. • Semi-InclusiveReactions: • RIA and DWIA describesonlylossofflux in onechannel, does not tellwherethefluxgoesanddoes not containanysecondaryreactionsorsidefeedingofchannels • Transport describeselasticandinelasticscattering, coupledchanneleffects, fulleventhistory • ExclusiveReactions (coherentproduction): • Phase coherence: Only QM applicable

  23. Model Ingredients: FSI • Kadanoff-Baymequation • fullequationcan not besolvedyet – not (yet) feasiblefor real worldproblems • Boltzmann-Uehling-Uhlenbeck (BUU) models • Boltzmann equationasgradientexpansionofKadanoff-Baymequations • includemean-fields • BUU with off-shellpropagation (essential forpropagatingbroadparticles): GiBUU • Cascademodels (typicaleventgenerators, NUANCE, GENIE, …) • nomean-fields, (no) Fermi motion • Theoretical Basis Simplicity Beijing 03/10

  24. GiBUUtransport • whatisGiBUU? semiclassical coupled channels transport model • general information (and code available): http://theorie.physik.uni-giessen.de/GiBUU/ • GiBUU describes (within the same unified theory and code) • heavy ion reactions, particle production and flow • pion and proton induced reactions • low and high energy photon and electron induced reactions • neutrino induced reactions ……..using the same physics input! And the same code! Beijing 03/10

  25. Model Ingredients: FSI • time evolution of spectral phase space density (for i = N, D,p,r, …) given by BUU equation • one equation for each particle species (61 baryons, 21 mesons) • coupled through the potential US and the collision integral Icoll • Cross sections from resonance model (and data) for W < 2.5 GeV • at higher energies (W > 2.5 GeV) particle production through string fragmentation (PYTHIA) one-particle spectral phase space density for particle species i Hamiltonian Beijing 03/10

  26. Pion production: model validationwithphotondata • GiBUUdescribesphoton-inducedpionproduction, in particularmomentumdistributionTAPS data(Eur. Phys. J A22 (2004)) Ca Pb Ca Pb Beijing 03/10

  27. CC nucleon knockout: nm56Fe  m- N X w FSI w/o FSI Dramatic FSI Effect E = 1 GeV Beijing 03/10

  28. NC inducedproton knockout: nm56Fe  nmpX • effectsof FSI on nucleonkineticenergyspectrumatEn = 1 GeV • fluxreductionathigherenergies • large numberofrescatterednucleonsatlowkineticenergies NC p Dcontribution to knock-out almost equals QE contribution (increases with E)  coupled-channel effect Beijing 03/10 Phys. Rev. C 74, 065502 (2006)

  29. Different approachestoidentify CCQE MiniBooNE K2K 0 ¼ + X 0 ¼ + 1 p + X QE induced QE induced ¢ induced (fakes) ¢ induced (fakes) Beijing 03/10 T.L. et al., NUFACT08 proceedings, arXiv:0809.3986

  30. MiniBooNE CCQE per nucleon T. Katori, NUINT09 QE-like - QE-fake, energyreconstructiondatacorrection model dependent • underestimate MiniBooNE by ~35% • agreement with other models • agreement with NOMAD • pion-electroproduction, former neutrino experiments, NOMADconsistent with MA = 1 GeV Beijing 03/10

  31. MiniBooNE Q2 distribution • CC º¹ on 12C averaged over MiniBooNE flux • QE-fakes: background! • reconstruction via • MiniBooNE “data” = Smith-Moniz Fermi gas with “modified Pauli blocking” and MA = 1.35 GeV • assume that non-QE background subtraction is perfect! • in addition: RPA correlations by Nieves et al. PRC 73 (2006) Beijing 03/10 arXiv:0909.5123 

  32. Energyreconstruction via CCQE • all QE-like events enter energy reconstruction! • reconstruction under assumption that QE-like = QE and with free kinematics: EB = 34 MeV error: “true” QE: ~ 11-17 % QE-like (MB): ~ 19-23 % QE-like (K2K): ~ 13-18 % Beijing 03/10

  33. Energyreconstruction via CCQE • all QE-like events enter energy reconstruction! • reconstruction under assumption that QE-like = QE and with free kinematics: EB = 34 MeV QE fakes “fill in oscillation dip”  error in extracted oscillation parameters Beijing 03/10

  34. CC pionproduction: nm56Fe  m-p X w FSI w/o FSI E= 1 GeV Beijing 03/10

  35. CC pionproduction: nm56Fe  m-p X • effectsof FSI on pionkineticenergyspectrumatEn = 1 GeV • strong absorption in Dregion • side-feedingfrom dominant p+ intop0 channel • secondarypionsthrough FSI ofinitial QE protons p+ p0 Spectradeterminedby¼-N-¢dynamics Beijing 03/10

  36. K2K and MiniBoonE CC1¼+ • single-¼+/QE ratio ¾1p+ / ¾0p+1pafter FSI: K2KdefinitionforCCQE-likecrosssection ¾1p+ / ¾0p+ after FSI: MiniBooNEdefinitionforCCQE-likecrosssection ¾1p+ / ¾QEbefore FSI: includingnuclearcorrectionslikemeanfieldsand Fermi motion ¾1p+ / ¾QE in thevacuum FSI corrected FSI corrected Beijing 03/10

  37. MiniBooNE NC 1¼0 • NC1¼0 data consistent with calculation without FSI! • possible origins: • elementary cross section too small • neutrino-flux prediction (cf. discrepancy in QE channel) • “data” contains “theory”: model dependence data: C. Anderson, NUINT09 bands:uncertainty of axial form factor Beijing 03/10 arXiv:0910.2835

  38. Summary • Quasielastic scattering events contain admixtures of Delta excitations •  excitations affect nucleon knockout, contaminate QE experiments • Energy reconstruction good up to 10 – 20%. Experiments want 5%! • Extraction of axial mass (1 GeV) strongly affected by nuclear structure (RPA correlations), difficult to get both absolute height and slope. Beijing 03/10

  39. Summary Particle production at neutrino energies of ~1 GeV Inclusive cross section dominated by  excitation, with QE contribution, good description of electroprod. Data Semi-inclusive particle production incl. coupled channel FSI in GiBUU straightforward, tested against A and A Extension to higher energies (5 – 280 GeV) successful for electroproduction, for neutrinos (OPERA) to be done, straightforward Beijing 03/10

More Related