Nuclear shadowing and antishadowing in deep inelastic scattering

1
Nuclear shadowing and antishadowing in
deep inelastic scattering
Stanley Brodsky Jian-Jun Yang Ivan Schmidt
Blois 2005
2
Motivation 1) NuTev neutrino deep inelastic
scattering
Many possible explanations.
3
2) Electromagnetic DIS in nuclei
antishadowing
shadowing
Leading twist effect.
4
Questions

• 1) What is the physics of (anti)shadowing ?
• 2) Is there any difference between
  electromagnetic vs weak (charged and neutral)
  currents in nuclei ?
• 3) How does this affect the sin2qW extraction ?

5
The Physics

• Shadowing destructive interference.
• Antishadowing constructive interference.

Coherence length gt Nucleon separation
Small momentum transfer
Diffraction
Reggeon exchanges
Interference of rescattering from different
nucleons
6
Pomeron Reggeons (even pseudoscalar) Oderon (real
phase)
Shadowing Antishadowing
Flavor dependent (isovector Reggeon) Different
for electromagnetic, neutral and charged currents
7
Calculation Glauber-Gribov multiple scattering
theory
and similar expressions for other quarks.
Nucleon structure functions
Compare with data (fix parameters)
8
Glauber
Nuclear structure functions
9
Neutrino nuclear DIS
Model predictions

• Bigger antishadowing for
• Different NC-CC effects only for

10

Monte Carlo simulation
Experimental ratios
sin2qW
Extraction of sin2qW
11
1) Calculate
Algorithm
2) Use
to calculate
to get
3) Use
12
Conclusions
3) Flavor dependence
4) More experiments needed