Dott. Antonio Botrugno

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Neutrino-Nucleus Interaction

• Dott. Antonio Botrugno
• Ph.D. course

UNIVERSITY OF LECCE (ITALY) DEPARTMENT OF
PHYSICS
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Inclusive cross section for neutrino scattering
off nuclei
Charge Current
Neutral Current

• Above nucleon emission threshold.
• The state of the emitted nucleon is not observed.

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A many-body theory to calculate
nuclear-responses at low and intermediate
transferred energy (10 - 300 MeV)
SCHEMATIC REPRESENTATION OF NUCLEAR RESPONSE
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WHY NEUTRINO - NUCLEUS ?
NUCLEUS USED AS A DETECTOR OF NEUTRINOS
NEUTRINOS USED AS PROBE TO STUDY NUCLEAR STRUCTURE

• Neutrino fluxes are sometimes not well known
• source uncertainty (solar, supernova, and
  geophysic neutrinos)
• oscillation phenomena

Neutrinos are an ideal probe to investigate
nuclear structure moreover they
are able to excite nuclear modes not accessible
to the electomagnetic probes.
We need an accurate knowledge of the
neutrino-nucleus cross sections to better
understand detector response.
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Cross Section
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Nuclear Models

• Mean Field (MF)
• Continuum Random Phase Approximation (RPA)
• Final State Interaction (FSI)

Microscopic Models
Phenomenological Model
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1) Mean Field Model
Single particle excitations
This model is inadequate in the Giant Resonance
Region where collective excitations are important.
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INPUT 1 Wood-Saxon Potential
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2) Continuum Random Phase Approximation
Collective excitations
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INPUT 2 Nucleon-Nucleon Interaction

• Landau-Migdal Type 1 (LM1)
• Landau-Migdal Type 2 (LM2)
• Polarization Potential (PP)

CC Processes
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3) Final State Interaction
APPROXIMATION
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Nuclear Response in a microscopic model

• 1p-1h Correlations

• np-nh Correlations

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3) Final State Interaction
APROXIMATION
INPUT 3
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Constraints and Prediction Power of the Models

• Photo-absorption.
• to set the FSI parameters
• Electron scattering.
• to test the prediction power of the model
• Sum rules
• to test the consistence of the calculation

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Photo-absorption
Data J. Ahrens et al., Nucl. Phys. A 251,
(1975), 479
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Constraints and Prediction Power of the Models

• Photo-absorption.
• to set the FSI parameters
• Electron scattering.
• to test the prediction power of the model
• Sum rules
• to test the consistence of the calculation

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Energy Region I) Quasielastic Peak
FSI
RPA
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Energy Region II) Giant Resonance
FSI
RPA
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Constraints and Prediction Power of the Models

• Photo-absorption.
• to set the FSI parameters
• Electron scattering.
• to test the prediction power of the model
• Sum rules
• to test the consistence of the calculation

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Comparison between electron and neutrino
scattering
In electron scattering the value of the cross
section decreases with increasing incoming energy
and/or scattering angle In neutrino scattering
the value of the cross section increases with
increasing incoming energy (and/or scattering
angle in giant resonance region).
The shapes of the neutrino cross sections are
very different to those of the electron cross
sections because 1) the axial vector part of the
weak current dominates in neutrino scattering. 2)
the particle-hole transitions in CC processes are
different to those of the electron scattering.
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I) Giant Resonance
II) Quasielastic Peak
CRPA Calculation
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Comparison between electron and neutrino
scattering
In electron scattering the value of the cross
section decreases with increasing incoming energy
and/or scattering angle In neutrino scattering
the value of the cross section increases with
increasing incoming energy (and/or scattering
angle in giant resonance region).
The shapes of the neutrino cross sections are
very different to those of the electron cross
sections because 1) the axial vector part of the
weak current dominates in neutrino scattering. 2)
the particle-hole transitions in CC processes are
different to those of the electron scattering.
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Comparison between electron and neutrino
scattering
II) Quasielastic Peak
I) Giant Resonance
CRPA calculation
MF calculation
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Conparison between electrons ed neutrinos
scattering
In electron scattering the value of cross section
decrease with increasing incoming energy and/or
scattering angle In neutrino scattering the value
of cross section increase with increasing
incoming energy (and/or scattering angle in giant
resonance region).
Shapes of neutrinos cross sections are very
different to electron cross section because 1)
the axial vector part of the weak current
dominates in neutrino scattering. 2) the
particle-hole transition in CC processes are
different to electron scattering.
Caution in testing the prediction accuracy of
neutrino scattering using electron
scattering. Caution in using the response
function extracted from electron scattering to
calculate neutrino cross sections.

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Comparison between various models
Nuclear Models should be used only in their range
of applicability.

CRPA has a large energy range of applicability.

FG Model of Smith e Monitz.
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CRPA Calculation
Angular distribution
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Total cross section including FSI effect
Landau-Migdal 1
Landau-Migdal 2
Polarization Potential

The sensitivity of the cross section to the
nucleon-nucleon interaction is 10-12 in giant
resonance region.
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The effect of FSI Model is a reduction of the
cross section of about 10 15 on all neutrino
processes.
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Some important proposals for the future
Main results

• The sensitivity of the cross section to the
  nucleon-nucleon interaction is 10-12 in giant
  resonance region.
• The effect of FSI Model is a reduction of the
  cross section of about 10 15 on all neutrino
  processes.

• Implementing the formalism for other nuclei.
• Application for know or expected neutrino fluxes
  solar, atmospheric, supernova, pion decay,
  beta-beam.
• Other processes at low energy

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Thomas-Reiche-Kuhn sum rules
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Total cross section including FSI effect.
Landau-Migdal 1
Landau-Migdal 2
Polarization Potential