Nuclear Modifications in Saturated Glauber Model from SPS to LHC Energies

1. Nuclear Modifications in Saturated Glauber Model from SPS to LHC Energies SzilveszterMiklósHarangozó Zimányi Winter School 2013 Supervisor: Dr. GergelyGáborBarnaföldi Wigner RCP of the HAS Department of Particle & Nuclear Physics Consultant: Dr. GáborPapp ELTE – TTK Department of Theoretical Physics

2. pQCDbased parton model • Nucleon-Nucleon reactions • Factorization: we assume, the process can be factorized into 3 independent phase

3. 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)

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

5. 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 pT-s for the parameter • Take a look at the tendency…

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

7. 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), RpA • Difference: Nuclear Effects Nuclear Effects where is the number of binary collisions

8. Nuclear Effects Multiple Scattering Nuclear Modifications of PDF’s Nuclear Effects • Classic and Saturated Glauber model • Dependence on the impact parameter, b • Intrinsic transverse momentum distribution broadens: • Suppression of the yield at low pT-s • Several parameterizations has been implemented by different groups

9. Parameters for the saturated Glauber model in pAcollisions Search for the universal Csat constant Maximum 3-4 collision with CSat≈ 0.35

10. 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

11. 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:

12. The kTpQCD v2.0 code PDF FF pQCD

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

14. The kTpQCD v2.1 code Example: New shadowing: EPS09s eps09s.cpp Ref.: 10.1007/JHEP07(2012)073

15. 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

16. 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

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

18. Thank you for your consideration!