Nuclear Modifications in Saturated Glauber Model from SPS to LHC Energies Szilveszter Miklós Harangozó Zimányi Winter School 2013 Consultant: Dr. Gábor Papp ELTE – TTK Department of Theoretical Physics Supervisor: Dr. Gergely Gábor Barnaföldi Wigner RCP of the HAS Department of Particle & Nuclear Physics

pQCD based parton model Nucleon-Nucleon reactions Factorization: we assume, the process can be factorized into 3 independent phase

pQCD based parton model We calculate the cross sections with a convolution described above. We characterize the PDFs & FFs as probability density functions, which can not be calculated perturbatively. Parton Distribution Function (PDF) hard partonic scattering Fragmentation Function (FF)

Improving the model 40% uncertanity is too much. Phenomenological input. Parton’s transverse (intrinsic) momenta have been taken into account. Assume: transverse momentum distribution is Gaussian:

The c.m. energy dependence of Comparison of experimental spectra and results of the calculations Uncertanities come from the Principle of Minimal Sensitivity The model is more sensitive at low p T -s for the parameter Take a look at the tendency…

The p T & dependence of best fit for every p T value for a fixed, p T independent values can be assumed best fit for the average p T intrinsic transverse momentum seems to decrease p T dependence of the dependence of the Good pp reference spectra can be obtained

Proton-Nucleus ( pA ) collision Experience: the yield differs from the expected: atomic number (A) times the one from pp spectra Measuring tool: Nuclear Modification Factor (NMF), R pA Difference: Nuclear Effects whereis the number of binary collisions Nuclear Effects

Multiple ScatteringNuclear Modifications of PDF’s Classic and Saturated Glauber model Dependence on the impact parameter, b Intrinsic transverse momentum distribution broadens: Suppression of the yield at low p T -s Several parameterizations has been implemented by different groups

Parameters for the saturated Glauber model in pA collisions Search for the universal C sat constant Maximum 3-4 collision with C Sat ≈ 0.35

Cronin- effect in the saturated Glauber model Dependency of the Cronin-peak’s maximum against the Atomic number ν : number of semihard collisions parameters fitted for experiments at fixed, peak stays put

Cronin- effect in the saturated Glauber model Dependency of the Cronin-peak’s maximum against the Atomic number shadowing and saturation also suppresses the spectra in fully saturated case we get the original dependency we can apply a correction to the formula:

The kTpQCD v2.0 code PDFFF pQCD

The kTpQCD v2.0 code Several parameterization can be probed within the same framework Original codes has been implemented Easy to add new type of PDFs, FFs, etc. Pro.:

The kTpQCD v2.1 code eps09s.cpp Example: New shadowing: EPS09s Ref.: Ref.: /JHEP07(2012)073

Reconstruction HIJING shadowing + Multiple scattering EPS09s shadowing Both parameterizations gives acceptable results For HIJING ν = 4 gives the best fit For RHIC results EPS09s is the best

Questions - Motivation Which nuclear effects cause the peripheral anomalies? Can we model model them? To claim a better understand of the Glauber-model Find the limits (or a better implementation) of the saturated picture

Summary pp reference first results on minimum bias collisions an updated code with “easy-to-upgrade” properties We have: We don’t have: good enough parameterization for LHC energies better understand of the peripheral collisions an updated code with “easy-to-upgrade” properties

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