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Soft physics at the LHC. A brief survey of diffraction New model for high energy proton-proton interactions, based on a full set of multi-Pomeron interactions , as well as including multichannel eikonal scattering The model description of the total, elastic and (low and
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Soft physics at the LHC A brief survey of diffraction New model for high energy proton-proton interactions, based on a full set of multi-Pomeron interactions, as well as including multichannel eikonal scattering The model description of the total, elastic and (low and high mass) diffractive cross sections; and the predictions for the LHC Alan Martin (Durham) October 2007 Ryskin, Martin, Khoze arXiv: 0710.2494
Soft interactions Hard diffraction
elastic unitarity e-W is the probability of no inelastic interaction.
includes low M dissociation High M dissociation
Evolution of elastic bare Pomeron amplitude Multi-Pomeron contribn
gn1 Y y g1m 0 amplitude containing full sum of multi-P diagrams gnm y’=Y-y
amp. of c-i intn elastic s(c-k) prob. of c in dy’ no additional i-k scatt
low M dissoc. given eikonal --- y0=2.3 for y evoln (M>2.5GeV) use 3-channel eikonal (results similar for 2-ch.) fi-Pomeron vertex: bi • each compt. bi same trans. size / differs in parton density • compts. differ in trans. size / max. density same CERN-ISR expts: 2 – 3 mb l fixed by CDF dsSD/dxLdt data s0 = ( bi ) 2 Model fit to existing soft pp data
CERN-ISR measurements of single dissocn at low mass elastic scattering inelastic scatt
SD energy dep. SD RP: 420 RP: 220 SD t dep.
f1: “large” f3: “small”
full multi-Pomeron contribn full 3-P contribn only first 3-P diagram
0.02 0.04 in EPJC(2000)
SD growth due to Pomeron interactions compensated by stronger absorption, i.e. decrease of S2 0.01 0.1 1-xL RP: 220 RP: 420
from the model actually directly related to elastic data
assuming point-like production – we fold in hard matrix element in a moment
Conclusions gnm = First, self-consistent multi-Pomeron, multi-ch eikonal of soft pp interactions All multi-P interactions collected in factors which describe absorption of intermediate partons during the evolution of the parton cascade Even with minimum no. of parameters, get satisfactory description of all available soft data --- model (B) favoured Inescapable consequence of absorption by low M in eikonal rescatt. and high M in multi-P intn: s(total) ~ 90 mb at LHC In principle, can predict all diffractive processes at LHC but important to measure low M SD etc. to constrain model