Transparencies pdf - Desy

| Γ pp (b) | 2
Study of the elastic scattering allows to determine how the strength Z of the interaction
depends on the impact parameter, b:
1
0.8
0.6
0.4
0.2
0
Implications for LHC - impact parameters for collisions
with new particle production vs generic inelastic collisions
(i) Impact parameter distribution in pp interaction
s 1/2 = 500 GeV
1.8 TeV
14 TeV
0 1 2
b [fm]
Γ(b) = 1 ≡ σinel = σel
2 Re Γ pp - | Γ pp | 2
Γh(s,b) = 1
2is
1
0.8
0.6
0.4
0.2
0
1
(2π) 2
0 1 2
b [fm]
Probability of inel. interaction:
- black disk limit (BDL).
d 2 qe iqb AhN(s,t)
Calculation uses
model of
Islam et al
P(b) = 2 ReΓ(b) − |Γ(b)| 2
Broadening of the distribution over b is primarily a result of Gribov diffusion.
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