1 / 39

Neutrino cross sections from a theoretical perspective Luis Alvarez-Ruso IFIC, Valencia

Euro n. Neutrino cross sections from a theoretical perspective Luis Alvarez-Ruso IFIC, Valencia. TexPoint fonts used in EMF. Read the TexPoint manual before you delete this box.: A A A A A A A A A A. Introduction. Neutrino - nucleus interactions are important for:

matia
Download Presentation

Neutrino cross sections from a theoretical perspective Luis Alvarez-Ruso IFIC, Valencia

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. Euron Neutrino cross sections from a theoretical perspectiveLuis Alvarez-RusoIFIC, Valencia TexPoint fonts used in EMF. Read the TexPoint manual before you delete this box.: AAAAAAAAAA

  2. Introduction • Neutrino-nucleus interactions are important for: • Oscillation experiments • º detection, Eºreconstruction, ºflux calibration • Electron-like backgrounds: • NC¼0 production (incoherent, coherent) • Photon emission in NC • Hadronic physics • Nucleon and Nucleon-Resonance (N-¢, N-N*) axial form factors • Strangeness content of the nucleon spin • Nuclear physics • Information about: nuclear correlations, MEC, spectral functions • nuclear effects: essential for the interpretation of the data

  3. Introduction • Most relevant processes in the few-GeV region: • Quasielastic scattering • Single pion production (incoherent and coherent)

  4. QE scattering • º detection: • Eºreconstruction: • Assumes that • Important for oscillations: • QE ¾ affect the expected sensitivities to oscillation parameters • Example: Fernandez, Meloni, arXiv:1010.2329 • ¯ beam hypothetical exp.: < Eº > 0.3 GeV, 16O target • Sensitivities to µ13 and ±CP vary ~ 10-30 % depending on the nuclear CCQE model

  5. º QE scattering dipole ansatz PCAC • The (CC) elementary process: where • Vector form factors: extracted from e-p, e-d data • Axial form factors:

  6. º QE scattering • The (CC) elementary process: • gA = 1.267 ï decay • MA= 1.016 § 0.026 GeV ( ) Bodek et al., EPJC 53 (2008) • MA from ¼electroproduction on p: • Connected to FA at threshold and in the chiral limit (m¼ =0) • Using models to connect with data ) • MAep= 1.069 § 0.016 GeV Liesenfeld et al., PLB 468 (1999) 20 • Hadronic correction (ChPT) Bernard et al., PRL 69 (1992) 1877 • MA = MAep - ¢MA , ¢MA =0.055 GeV ) MA = 1.014 GeV

  7. º QE scattering • Relativistic Global Fermi GasSmith, Moniz, NPB 43 (1972) 605 • Impulse Approximation • Fermi motion • Pauli blocking • Average bindingenergy • Explains the main features of the (e,e’)inclusive¾ in the QE region • Fails in the details (nuclear dynamics needed)

  8. º QE scattering • Spectral functions of nucleons in nuclei • The nucleon propagator can be cast as • Sh(p)Ãhole (particle) spectral functions: 4-momentum (p) distributions of the struck (outgoing) nucleons • §Ã nucleon selfenergy • Better description of (e,e’)inclusive¾ Benhar et al., PRD 72 (2005) Ankowski, Sobczyk, PRC 67 (2008) Nieves et al., PRC 70 (2004) Leitner et al., PRC 79 (2009)

  9. º QE scattering • Relativistic mean field • Impulse Approximation • Initialnucleon in a bound state (shell) • ªi : Dirac eq. in a mean field potential (!-¾ model) • Finalnucleon • PWIA • RDWIA: ªf : Dirac eq. for scattering state • Glauber • Problem: nucleon absorption that reduces the c.s. • Can be used to study: • 1Nknockout • inclusive processes: with only Re[Vopt] Martinez et al., PRC 73 (2006) Budkevich, Kulagin, PRC 76 (2007) Complex optical potential

  10. º QE scattering • RPA long range correlations • Incorporates N-hole and ¢-hole states • V: ¼, ½ exchange, Landau-Migdal parameter g’ • Describes correctly ¹ capture on 12C and LSNDCCQE • Collective effect: important at low Q2for º QE Singh, Oset, NPA 542 (1992) Marteau, Delorme, Ericson, NIMA 76 (2000) Nieves et al., PRC 70 (2004)

  11. º QE scattering • Comparison toMiniBooNE¾ • At Eº =0.8 GeV: ¾th ~ 4.5-5 < ¾MB ~ 7 £ 10-38 cm2 • CCQE models with MA~1 GeV cannot reproduce MiniBooNE¾ Source: Boyd et al., AIP Conf. Proc. 1189 Data: MiniBooNE, PRD 81, 092005 (2009)

  12. º QE scattering • Comparison toMiniBooNE¾ • Proposed solutions: • MA=1.35 § 0.17 GeV (RFG) MiniBooNE, PRD 81, 092005 (2010) • However, MA>1 GeV is incompatible with: • data • ¼electroproduction on p (at low Q2) • NOMAD: MA = 1.05 § 0.02(stat) § 0.06(sys) GeV Lyubushkin et al., EPJ C63

  13. º QE scattering • Comparison toMiniBooNE¾ • Proposed solutions: • MA=1.37 GeV (RDWIA) Butkevich, arXiv:1006.1595 • Fit to d¾/dQ2 (shape only) • Better than RFG at low Q2

  14. º QE scattering • Comparison toMiniBooNE¾ • Proposed solutions: • MA=1.37 GeV (RDWIA) Butkevich, arXiv:1006.1595 • Fit to d¾/dQ2 (shape only) • Good description of double differential cross section

  15. º QE scattering • Comparison toMiniBooNE¾ • Proposed solutions: • MA=1.6 GeV (Spectral Function) Benhar, Coletti, Meloni, PRL 105 (2010) • Fit to d¾/dQ2

  16. º QE scattering • Comparison toMiniBooNE¾ • Proposed solutions: • MA=1.343 § 0.060 GeV (Spectral Function) Juszczak, Sobczyk, Zmuda, arXiv:1007.2195 • Fit to double differential c. s. including flux uncertainty • Momentum transfer cut qcut = 500 MeV to exclude IA breakdown region: insufficient to reconcile MiniBooNE with exp. on deuterium

  17. º QE scattering • Comparison toMiniBooNE¾ • Many body RPAMartini et al., PRC 80 (2009), 81 (2010) • RPA: small reduction • Large2p-2h contribution to º12C mainly from (2),(3),(3’)

  18. º QE scattering • Comparison toMiniBooNE¾ • Many body RPAMartini et al., PRC 80 (2009), 81 (2010) 12C(e,e’)X • RPA: small reduction • Large2p-2h contribution to º12C mainly from (2),(3),(3’) • MEC absent (but important for (e,e’) in the dip region) Gil, Nieves, Oset, NPA627

  19. º QE scattering • Comparison toMiniBooNE¾ • Many body RPAMartini et al., PRC 80 (2009), 81 (2010) • RPA: small reduction • Large2p-2h contribution to º12C mainly from (2),(3),(3’) • Prediction: smaller2p-2h contribution to anti-º12C • Detailed tests against e-scattering data are necessary

  20. 1¼ production • Reactions • Incoherent: • Coherent: • CC • NC • Relevant for oscillations • NC¼0: e-like background to º¹!ºe searches (µ13 & ±$CP violation) • Source of CCQE-like events (in nuclei), needs to be subtracted for a good Eº reconstruction

  21. 1¼ production • Reactions • Incoherent: • Coherent: • CC • NC • Relevant for oscillations • NC¼0: e-like background to º¹!ºe searches (µ13 & ±$CP violation) • Source of CCQE-like events (in nuclei), needs to be subtracted for a good Eº reconstruction Leitner, Mosel, PRC 81

  22. 1¼ production • Elementary process: • Dominated by resonance production • At Eº ~ 1 GeV: ¢(1232) • N-¢ transition current: • Form factors , Helicity amplitudes (A1/2, A3/2, S1/2)

  23. 1¼ production • Elementary process: • Dominated by resonance production • Rein-Sehgal model: Rein-Sehgal, Ann. Phys. 133 (1981) 79. • Used by almost all MC generators • Relativistic quark model of Feynman-Kislinger-Ravndal with SU(6) spin-flavor symmetry • Helicity amplitudes for 18 baryon resonances • Lepton mass = 0 • Corrections: • Poor description of ¼ electroproduction data on p Kuzmin et al., Mod. Phys. Lett. A19 (2004) Berger, Sehgal, PRD 76 (2007) Graczyk, Sobczyk, PRD 77 (2008)

  24. 1¼ production • Elementary process: • Dominated by resonance production • Rein-Sehgal model: Rein-Sehgal, Ann. Phys. 133 (1981) 79. • Used by almost all MC generators • Relativistic quark model of Feynman-Kislinger-Ravndal with SU(6) spin-flavor symmetry • Helicity amplitudes for 18 baryon resonances • Lepton mass = 0 • Corrections: • Poor description of ¼ electroproduction data on p Kuzmin et al., Mod. Phys. Lett. A19 (2004) Berger, Sehgal, PRD 76 (2007) Graczyk, Sobczyk, PRD 77 (2008)

  25. 1¼ production • N-¢ transition current • Helicity amplitudes can be extracted from data on ¼photo- and electro-production • Unitary isobar model MAID Drechsel, Kamalov, Tiator, EPJA 34 (2007) 69 • Uses world data • for all 4 star resonances with W<2 GeV • Unitary isobar model+Regge-pole BG at high energies I. Aznauryan, PRC67 • Dispersion relations • CLAS (JLab) data • 1st and 2nd resonance regions: ¢(1232), N*(1440), N*(1520), N*(1535)

  26. 1¼ production • N-¢ transition current • Axial form factors PCAC Adler model

  27. 1¼ production • N-¢axial form factors: determination of CA5(0) and MA ¢ • From ANL and BNL data on • with large normalization (flux) uncertainties • Graczyk et al., PRD 80 (2009) • Deuteron effects • Non-resonant background absent • CA5(0)=1.19 § 0.08, MA ¢= 0.94 § 0.03 GeV • Hernandez et al., PRD 81 (2010) • Deuteron effects • Non-resonant background fixed by chiral symmetry • CA5(0)=1.00 § 0.11 GeV, MA ¢= 0.93 § 0.07 GeV • 20 % reduction of the GT relation off diagonal GT relation

  28. 1¼ production • Incoherent 1¼production in nuclei • Large number of excited states )semiclassical treatment • ¼propagation (scattering, charge exchange), absorption (FSI) • Most models cannot calculate this reaction channel. Exceptions: • MC generators: NUANCE, NEUT, GENIE, NuWro • Cascade: Ahmad et al., PRD 74 (2006) • Transport: GiBUU

  29. 1¼ production • Incoherent 1¼production in nuclei (FSI) • NuWroJ. Sobczyk et al. • Intranuclear cascade • ¼propagation: empirical ¼-N vacuum ¾ • ¼absorption: ¼-A absorption data • Ahmad et al., PRD 74 (2006) • Cascade (~NuWro) • In-medium modification of ¢ spectral f. (only in the production) • GiBUU • Transport: one approach for eA, ºA, pA, ¼A reactions • ¼, N but also ¢ are propagated • Main absorption mech.: ¢N!N N, ¼N N!N N

  30. 1¼ production • Comparison to the ¾(CC¼+)/¾(CCQE-like) ratio at MiniBooNE Athar et al. NuWro GiBUU

  31. 1¼ production • Coherent pion production • CC • NC • Takes place at low q2 • Very small cross section • At q2» 0, axial current not suppressed NEUT Hiraide@NuInt09

  32. 1¼ production • Coherent pion production models • PCAC • In the q2=0 limit, PCAC is used to relate ºinduced coherent pion production to ¼Aelastic scattering • Extrapolated to q2 0 • R&S: describe ¼A in terms of ¼N scattering • B&S, P&S: use ¼A data • Problems: Hernandez et al., PRD 80 (2009) 013003 • q2=0 limit neglects important angular dependence at low energies • R&S: The ¼A elastic description is not realistic • B&S,P&S: spurious initial ¼ distortion present in ¼Abut not in coh¼ Rein & Sehgal NPB 223 (83) 29 Berger & Sehgal, PRD 76 (2007),79 (2009) Paschos & Schalla, PRD 80 (2009),

  33. 1¼ production • Coherent pion production models • PCAC • In the q2=0 limit, PCAC is used to relate ºinduced coherent pion production to ¼Aelastic scattering • Extrapolated to q2 0 • R&S: describe ¼A in terms of ¼N scattering • B&S, P&S: use ¼A data • Problems of PCAC models: less relevant as the energy increases • NOMAD: ¾=72.6 § 8.1(stat) § 6.9(syst) £ 10-40 cm2 • Consistent with RS:¾¼ 78£10-40 cm2 Rein & Sehgal NPB 223 (83) 29 Berger & Sehgal, PRD 76 (2007),79 (2009) Paschos & Schalla, PRD 80 (2009),

  34. 1¼ production • Coherent pion production • Microscopic models: • ¢ excitation is dominant • ¢ properties change in the nuclear medium • ¼distortion: DWIA with optical potential based on ¢-hole model • Treatment is consistent with incoherent ¼ production • Valid only at low energies Singh et al., PRL 96 (2006) LAR et al, PRC 76 (2007) Amaro et al., PRD 79 (2009) Nakamura et al., PRC 81 (2010)

  35. 1¼ production • Coherent pion production Boyd et al., AIP Conf. Proc. 1189

  36. 1¼ production • Coherent pion production • SciBooNE:PRD 81 (2010) • NC ¼0¾ compatible with R&S • CC¼+/NC¼0=0.14+0.30-0.28 • Theoretical models predict CC¼+/NC¼0» 1-2 ! Boyd et al., AIP Conf. Proc. 1189

  37. Conclusions • New data with high statistics available • Comparison shows discrepancies that await explanation (not fits) • QE: 2p2h and MEC more important that in (e,e’) at fixed energy • Incoherent 1¼ production data underestimated • Comparison to inclusive data is needed • SciBooNE CC¼+/NC¼0=0.14+0.30-0.28for 1¼ coherent is incompatible with theoretical results

  38. º QE scattering • Comparison toMiniBooNE¾ • Model dependence in data: • Background (CCQE-like) depends on the ¼ propagation (absorption and charge exchange) model (NUANCE) • Eº reconstruction (unfolding) Source: Boyd et al., AIP Conf. Proc. 1189 Data: MiniBooNE, PRD 81, 092005 (2009)

  39. 1¼ production • Reactions • Incoherent: • Coherent: • CC • NC • Relevant for oscillations • NC¼0: e-like background to º¹!ºe searches (µ13 & ±$CP violation) • Source of CCQE-like events (in nuclei), needs to be subtracted for a good Eº reconstruction Leitner, Mosel, PRC 81

More Related