Neutrino interactions with nucleons and nuclei
1 / 39

Neutrino Interactions with Nucleons and Nuclei - PowerPoint PPT Presentation

  • Uploaded on

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.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
Download Presentation

PowerPoint Slideshow about ' Neutrino Interactions with Nucleons and Nuclei' - jeanette-brown

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.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Neutrino interactions with nucleons and nuclei
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

Soudan Mine,


770 km

Homestake Mine


1300 km

Beijing 03/10

Long baseline experiments
Long baselineexperiments

M. Wascko

Beijing 03/10

Neutrino oscillation search
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

Oscillation minium at miniboone
Oscillation Minium atMiniBooNE

Beijing 03/10


Beijing 03/10

  • Neutrino detectorsnowadays all contain (heavy) nuclei, haveto understand interactionsofneutrinoswith matter

  • Interactions ofneutrinoswithnucleimaymaketheidentificationofelementaryprocesses, like knock-out, pion-productionorqescatteringdifficult.


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

The Rebirth of Low Energy Nuclear Physics

Low-Energy Nuclear Physics

determines response

of nuclei to neutrinos

Beijing 03/10




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

Model ingredients isi
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

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

Neutrino nucleon cross section
Neutrino nucleoncrosssection


single ¼







10-38 cm² = 10-11 mb

P. Lipari, Nucl. Phys. Proc. Suppl. 112, 274 (2002)

Beijing 03/10

Quasielastic scattering

  • reactions:

  • hadronic current:


  • 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

Quasielastic scattering1

Beijing 03/10

Quasielastic scattering axial mass
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

Pion production through resonance excitation
Pion productionthroughresonanceexcitation

  • 13 resonanceswith W < 2 GeV

  • pionproductiondominatedbyP33(1232) resonance:

  • CVfromelectrondata (MAID analysiswith CVC)

  • CAfrom fit toneutrinodata(experiments on hydrogen/deuterium)


10 % error in C5A(0)


discrepancy between ANL and BNL data  uncertainty in axial form factor

Beijing 03/10

Cc pion production on free nucleons
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

Pion production through
Pion productionthrough¢

New V, old A

New V, new A

averagedover ANL flux, W < 1.4 GeV

Beijing 03/10

Beijing 03/10

Medium modifications of the inclusive cross section
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



      !med = P + coll

      collisional broadening


Beijing 03/10

Model validation electron scattering
Model validation: electronscattering

PRC 79, 034601 (2009)

Beijing 03/10

Transport vs quantummechanics
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

Model ingredients fsi
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


Beijing 03/10

Gibuu transport

  • whatisGiBUU? semiclassical coupled channels transport model

  • general information (and code available):

  • 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

Model ingredients fsi1
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


Beijing 03/10

Pion production model validation with photon data
Pion production: model validationwithphotondata

  • GiBUUdescribesphoton-inducedpionproduction, in particularmomentumdistributionTAPS data(Eur. Phys. J A22 (2004))





Beijing 03/10

Cc nucleon knockout n m 56 fe m n x
CC nucleon knockout: nm56Fe  m- N X


w/o FSI

Dramatic FSI Effect

E = 1 GeV

Beijing 03/10

Nc induced proton knockout n m 56 fe n m px
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)

Different approaches to identify ccqe
Different approachestoidentify CCQE



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

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

Miniboone q 2 distribution
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


Energy reconstruction via ccqe
Energyreconstruction via CCQE

  • all QE-like events enter energy reconstruction!

  • reconstruction under assumption that QE-like = QE and with free kinematics:

EB = 34 MeV


“true” QE: ~ 11-17 %

QE-like (MB): ~ 19-23 %

QE-like (K2K): ~ 13-18 %

Beijing 03/10

Energy reconstruction via ccqe1
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

Cc pion production n m 56 fe m p x
CC pionproduction: nm56Fe  m-p X


w/o FSI

E= 1 GeV

Beijing 03/10

Cc pion production n m 56 fe m p x1
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




Beijing 03/10

K2k and miniboone cc1
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

Miniboone nc 1 0
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



  • 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


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