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Page 1: Energy loss and in finite size QCD medium · Energy loss and in finite size QCD medium Alejandro Ayala ICN-UNAM November, 2006. Radiative vs. Collisional energy loss Single non-photonic

Energy loss and in finite size QCD medium

Alejandro AyalaICN-UNAM

November, 2006

Page 2: Energy loss and in finite size QCD medium · Energy loss and in finite size QCD medium Alejandro Ayala ICN-UNAM November, 2006. Radiative vs. Collisional energy loss Single non-photonic

Radiative vs. Collisional energy lossSingle non-photonic electron puzzle at RHIC

S. Wicks, W. Horowitz, M. Djordjevic and M. Gyulassy, nucl-th/0512076

Page 3: Energy loss and in finite size QCD medium · Energy loss and in finite size QCD medium Alejandro Ayala ICN-UNAM November, 2006. Radiative vs. Collisional energy loss Single non-photonic

Energy loss issues

Collisional vs radiative energy lossesRunning of αs

Non-perturbative calculations usingAdS/CFT and duality argumentsFinite size effects

Page 4: Energy loss and in finite size QCD medium · Energy loss and in finite size QCD medium Alejandro Ayala ICN-UNAM November, 2006. Radiative vs. Collisional energy loss Single non-photonic

S. Peigné, P.B. Gossiaux and T. Gousset, hep-ph/0509185

Energy loss computed by slowing down of parton inducedby medium produced electric field in Abelian approximation

Retardation effects: A fast parton produced in the mediumneeds to travel some distance before losing energy at thehighest rate.Conclusion: finite zise reduces the rate of energy loss.

Page 5: Energy loss and in finite size QCD medium · Energy loss and in finite size QCD medium Alejandro Ayala ICN-UNAM November, 2006. Radiative vs. Collisional energy loss Single non-photonic

M. Djordjevic, nucl-th/0603066Perturbative collisional energy loss, 2 → 2 processesin a finite QCD medium

Condition for interaction between jet andmedium parton to occur inside finite QCDmedium of size L.Conclusion: finite size does not affect the rateof energy loss.

Page 6: Energy loss and in finite size QCD medium · Energy loss and in finite size QCD medium Alejandro Ayala ICN-UNAM November, 2006. Radiative vs. Collisional energy loss Single non-photonic

Finite size effects

AA

BB

Particle production region

Q: Does the size of the interaction region, whereparticles are produced, play a role in the description of particle spectra?

Page 7: Energy loss and in finite size QCD medium · Energy loss and in finite size QCD medium Alejandro Ayala ICN-UNAM November, 2006. Radiative vs. Collisional energy loss Single non-photonic

Finite size effects

Qualitatively, finite size effects produce a broader transverse momentum spectrum due to Heisenberg uncertainty principle since the more localized the states are in coordinate space, the wider their spread will be in momentum space.

Page 8: Energy loss and in finite size QCD medium · Energy loss and in finite size QCD medium Alejandro Ayala ICN-UNAM November, 2006. Radiative vs. Collisional energy loss Single non-photonic

Bosons

Page 9: Energy loss and in finite size QCD medium · Energy loss and in finite size QCD medium Alejandro Ayala ICN-UNAM November, 2006. Radiative vs. Collisional energy loss Single non-photonic

Momentum distribution

Thermal occupation factorincludinng radial expansion

Wigner transform for bosons

Page 10: Energy loss and in finite size QCD medium · Energy loss and in finite size QCD medium Alejandro Ayala ICN-UNAM November, 2006. Radiative vs. Collisional energy loss Single non-photonic
Page 11: Energy loss and in finite size QCD medium · Energy loss and in finite size QCD medium Alejandro Ayala ICN-UNAM November, 2006. Radiative vs. Collisional energy loss Single non-photonic

A.A. E. Cuautle, J. Magnin, L.M. Montaño & A. Raya, Phys. Lett. B 634, 200 (2006)

Page 12: Energy loss and in finite size QCD medium · Energy loss and in finite size QCD medium Alejandro Ayala ICN-UNAM November, 2006. Radiative vs. Collisional energy loss Single non-photonic

Rπ=8 fm, βπ=0.6,Tπ=120 MeV

Page 13: Energy loss and in finite size QCD medium · Energy loss and in finite size QCD medium Alejandro Ayala ICN-UNAM November, 2006. Radiative vs. Collisional energy loss Single non-photonic

Fermions

Page 14: Energy loss and in finite size QCD medium · Energy loss and in finite size QCD medium Alejandro Ayala ICN-UNAM November, 2006. Radiative vs. Collisional energy loss Single non-photonic

Momentum distribution

Thermal occupation factorincludinng radial expansion

Wigner transform for fermions

Page 15: Energy loss and in finite size QCD medium · Energy loss and in finite size QCD medium Alejandro Ayala ICN-UNAM November, 2006. Radiative vs. Collisional energy loss Single non-photonic
Page 16: Energy loss and in finite size QCD medium · Energy loss and in finite size QCD medium Alejandro Ayala ICN-UNAM November, 2006. Radiative vs. Collisional energy loss Single non-photonic

A.A., E. Cuautle, J. Magnin, L.M. Montaño, nucl-th/0603039, to appear in PRC

Rπ=Rp=8 fmβπ=0.6 βp=0.53 (10% smaller than βπ)

Tπ=Tp=117 MeV

Page 17: Energy loss and in finite size QCD medium · Energy loss and in finite size QCD medium Alejandro Ayala ICN-UNAM November, 2006. Radiative vs. Collisional energy loss Single non-photonic

Scaling: R=R0 +C (Npart/2)1/3

R0 = 1fm, C = 1.28 fm

Page 18: Energy loss and in finite size QCD medium · Energy loss and in finite size QCD medium Alejandro Ayala ICN-UNAM November, 2006. Radiative vs. Collisional energy loss Single non-photonic

Two pion correlations

Page 19: Energy loss and in finite size QCD medium · Energy loss and in finite size QCD medium Alejandro Ayala ICN-UNAM November, 2006. Radiative vs. Collisional energy loss Single non-photonic

R vs PHENIX data

Page 20: Energy loss and in finite size QCD medium · Energy loss and in finite size QCD medium Alejandro Ayala ICN-UNAM November, 2006. Radiative vs. Collisional energy loss Single non-photonic

10-7

10-6

10-5

10-4

10-3

10-2

10-1

1

10

10 2

10 3

0 1 2 3 4 5 6 7 8 9 10Pt (GeV/c)

1/2π

*ptd

N/d

pt

Page 21: Energy loss and in finite size QCD medium · Energy loss and in finite size QCD medium Alejandro Ayala ICN-UNAM November, 2006. Radiative vs. Collisional energy loss Single non-photonic

ConclusionsConsidering finite size of particle production region, proton and pion spectra well described.Spectra from discrete set of states.Similar analysis possible for heavy quark produced in finite QCD medium?