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A Novel Heavy Quark Suppression Mechanism in the QGP

Time evolution. A Novel Heavy Quark Suppression Mechanism in the QGP. Ivan Vitev, Nuclear Theory, T-16 , LANL. "Characterization of the Quark-Gluon Plasma with Heavy Quarks” Seminar June 25 - 28, 2008, Bad Honnef, Germany. Outline of the Talk. Jet tomography of the QGP

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A Novel Heavy Quark Suppression Mechanism in the QGP

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  1. Time evolution A Novel Heavy Quark Suppression Mechanism in the QGP Ivan Vitev, Nuclear Theory, T-16 , LANL "Characterization of the Quark-Gluon Plasma with Heavy Quarks” Seminar June 25 - 28, 2008, Bad Honnef, Germany

  2. Outline of the Talk • Jet tomography of the QGP • Success of jet quenching for light hadrons, QGP tomography • The heavy quark puzzle at RHIC. A space-time picture of hadronization • Collisional dissociation of hadrons in dense QCD matter • Dissociation: new approach to D- and B-mesons suppression in the QGP • Light cone wave-functions. Mesons propagation in matter • Phenomenological results for RHIC and the LHC • Heavy resonances and partial chiral symmetry restoration • Hadrons and symmetry. Formation time of resonances in the medium • Interaction and decay of heavy resonances in matter • Experimental detection techniques • Summary and outlook • Universal modification of fragmentation functions in the QGP Talk based upon: A.Adil, I.Vitev, Phys. Lett. B649 (2007) Ch.Markert, R.Bellwied, I.Vitev, Phys. Lett. B to be submitted R. Sharma, I.Vitev, in progress

  3. Light Hadron Quenching • Nuclear modification factor • Predictions of this formalism tested vs • particle momentum, C.M. energy, centrality I.V., Phys.Lett.B 639 (2006) • Constrainedby the gluon rapidity (entropy) density

  4. Non-Photonic Electron / Heavy Flavor Quenching Proceed the same way to heavy flavor in A+A collisions • Single electron measurements (presumably from heavy quarks) may be • problematic M.Djordjevic, M.Gyulassy, Nucl.Phys.A (2004) • Radiative Energy Loss using (D)GLV • (both c + b) • Radiative + Collisional + Geometry • (both c + b) (overestimated) • Deviation by a factor of two • Is it accidental or is it symptomatic? S. Wicks et al., Nucl.Phys.A (2007)

  5. The Space-Time Picture of Hadronization In mesoscopic systems one has to account for the space-time evolution • Inside-outside cascade J.D. Bjorken, Lect.NotesPhys.56, (1987) • Correctly accounts for the leading energy and mass dependence. Lack of control over t0 • Outside-inside cascade A. Bialas, M.Gyulassy, Nucl.Phys.B 291, (1987) • Correctly points at the reduction of tform at large values of x. Specific for Lund string fragmentation. Mass dependence obscured

  6. Hadron Parton QGP extent (~5 fm) B D 20 fm 0.4 fm 1.5 fm Evaluating the Formation Times • Problem: treated in the same way as light quarks + • Fragmentation and dissociation of hadrons from heavy quarks inside the QGP

  7. Time evolution Collisional Dissociation of D / B Mesons • Conceptually different approach to heavy flavor suppression A. Adil, I. Vitev, Phys. Lett. B649, 139 (2007), hep-ph/0611109

  8. Light Cone Wave Functions - Transverse momentum scale From general theory of LCWF for the lowest-lying Fock state - Longitudinal momentum fractions S.Brodsky, D.S.Hwang, B.Q.Ma, I.Schmidt, Nucl.Phys.B 592 (2001) • Results for heavy flavor • Expansion in Fock components LO Fock component Mean Peaked at large x • Models such as coalescence should use • plausible wave functions, especially for heavy flavor

  9. Medium-Modified Heavy Meson Initial distribution: Resum using GLV themultiple scattering in impact parameter (B,b) space • Heavy meson acoplanarity: ? • Broadening (separation)the q q-bar pair:

  10. Initial Conditions (Hard Parton Spectra) Simultaneous fragmentation and dissociation call for solving a system of coupled equations I.V.,T.Goldman,M.Johnson,J.W.Qiu, Phys.Rev.D74 (2006) • Example: • radioactive • decay chain • Initial • conditions • Proposed back-2-back D / B • triggered correlations

  11. Heavy Meson Dissociation at RHIC and LHC Coupled rate equations • The asymptotic solution in the QGP - • sensitive to t0~0.6 fm and expansion • dynamics • Features ofenergy loss • B-mesons as suppressedas D-mesons • at pT~ 15-20 GeV at the LHC Unique feature A. Adil, I. Vitev, Phys. Lett. B649, 139 (2007)

  12. Quenching of Non-Photonic Electrons • Full semi-leptonic decays of C- and B- • mesons and baryons included. PDG • branching fractions and kinematics. • PYTHIA event generator • Similar to light , however, different • physics mechanism • B-mesons are included. They give a • major contribution to (e++e-) Note on applicability D-, B-mesons to (e++e-) to 25 GeV

  13. A+A Areas of Improvement • Incorporate radiative and collisional energy loss at really high pT • Main criticism: what are the modifications to a fragmentation process, • modified fragmentation functions, coalscence, … ( We wanted to solve this, the hierarchy problem, GUT, the baryon asymmetry, dark matter … but we couldn’t in the same paper ) These are not “modified fragmentation functions” A. Majumder, X.N.Wang (2008)

  14. A Possible Path Definition of the fragmentation functions • The apparent duality between • parton distribution functions • and fragmentation functions is • understandable From D(z) parameterizations or LCWF extract information about matrix elements We may gain insight of universal (T) modifications to fragmentation functions R. Sharma, I. Vitev, in prepration

  15. Effects of Partial Chiral Symmetry Restoration Kaon Lagrangian • Scale of chiral symmetry restoration - Includes approximately strange quarks Mass shifts G. Brown, M.Rho, Rev. Mod. Phys., (2001) Width broadening Phi meson L. Holt, K.Haglin, J. Phys. G31, S245 (2005) Manifestation for baryons L. Glozman, Phys.Lett. B475, 329 (2000) • Evidence for possible chiral • symmetry restoration • Important to include baryons • (,*) in experimental searches • at finite T

  16. Motivation / Estimates - a Simple Case • Mass of heavy resonances: falls in the right region to ensure early formation • Quick evaluation ( z = 0.7 ) • QGP formation (in the absence of dynamical • calculation) • Cross sections and z distributions

  17. Formation Time of Resonances • Distributions • One has to approximate fragmentation functions. Normalizations cancel in the ratio RHIC LHC

  18. In-medium Lifetime (Stronger Constraints) • Spectral function: medium broadening Remember the dilation factor Reduction if the lifetime is critical if any effects are to be observed in the resonance channel (upper pT limit) • URQMD study: any signal in pT 0-2 GeV strongly affected by hadronic rescattering of decay products (lower pT limit) L. Holt, K.Haglin, J. Phys. G31, S245 (2005) Phi meson M.Bleicher et al., Phys. Lett. B530, 81 (2002)

  19. Triggered Measurements • Ensure maximum medium sizewithout changing the formation times pT associated pT trigger • There is always a time distribution • Many of the resonances will be dissociated. We are concerned with those that survive .

  20. Summary of Open Heavy Flavor Suppression • Collisional QGP-induced B- / D-meson dissociation • Derived formation and dissociation times in the QGP. They are short • Solved the set of coupled rate equations. Moresensitive to QGP • properties and formation / expansion dynamics than e-loss • Found that suppression of non-photonic electrons from heavy mesons, • including B, is large. Not inconsistent with light pions • B-mesons are as suppressedasD-mesons at pT ~ 10 GeV,unique • Toward experimental resolution of the B- / D- puzzle • Identify the B- and D-mesoncontribution to the inclusive electron spectra • and the suppression factor RAAseparatelyforBsandDs • This will certainly motivate us to improve the calculation: modified fragmentation functions (really) and folding in energy loss. • Searches for chiral symmetry restoration • Identified the phase space and channels if those searches are to be done experimentally wit heavy resonances.

  21. Outline of the Talk • Jet tomography of the QGP • Success of jet quenching for light hadrons, QGP tomography • The heavy quark puzzle at RHIC. A space-time picture of hadronization • Collisional dissociation of hadrons in dense QCD matter • Dissociation: new approach to D- and B-mesons suppression in the QGP • Light cone wave-functions. Mesons propagation in matter • Phenomenological results for RHIC and the LHC • Heavy resonances and partial chiral symmetry restoration • Hadrons and symmetry. Formation time of resonances in the medium • Interaction and decay of heavy resonances in matter • Experimental detection techniques • Summary and outlook • Universal modification of fragmentation functions in the QGP Talk based upon: A.Adil, I.Vitev, Phys. Lett. B649 (2007) Ch.Markert, R.Bellwied, I.Vitev, Phys. Lett. B to be submitted R. Sharma, I.Vitev, in progress

  22. Jet Tomography Determining the properties of the QGP: SPS RHIC LHC I.V., M.Gyulassy, Phys.Rev.Lett. 89 (2002) F.Karsch, Nucl.Phys.A698 (2002)

  23. Single inclusive pion suppression at the LHC Running Fixed • High pT suppression at the LHC can be • comparable and smaller than at RHIC • LHC quenching follows the steepness • of the partonic spectra • Reduced sensitivity to medium properties S.Wicks et al., in progress

  24. Direct photon at the LHC • Direct photons also have limited sensitivity: isospin effects, • cold nuclear matter e-loss Prompt photons + Fragmentation photons • Better jet interaction • measures? • Direct photon tagging: • can be compromised by • fragmentation photons

  25. Non-Photonic Electron / Heavy Flavor Quenching • Langevin simulation of heavy quark • diffusion • Radiative and collisional energy loss S. Wicks et al., (2005) N. Armesto et al., (2006) • Ratio: • Opacity of the QGP H. van Hees, R. Rapp, (2005) G. Moore, D.Teaney (2005) • Diffusion coefficient D and eventually • Existence of heavy heavy • resonancesnear Tc in the QGP

  26. The Path Forward • An interesting idea valid physics explanation • To understand heavy flavor modification in the QGP we need direct and • separate measurements of D- and B-mesons, excellent statistics Measurable at RHIC Measurable at the LHC W.Horowitz, M. Gyulassy, (2007) A.Adil, I.Vitev, Phys. Lett. B (2006) Meson dissociation PQCD, Transport String theory AdS/CFT 50-100 10-15 PT [GeV] Never

  27. Heavy Flavor Elliptic Flow and Suppression Test coalescence model fits to the v2 of light hadrons via heavy flavor Understand the structure of mesons light cone wave functionsc Sensitive to the opacity of the QGP and its formation time D. Molnar (2004) A. Adil, I. Vitev, Phys.Lett.B (2007)

  28. Heavy Quark Production and Correlations • Fast convergence of the perturbative • series • Possibility for novel studies ofheavy • quark-triggered (D and B) jets: hadron • composition of associated yields

  29. Scales in Thermalized QGP (GP) • Experimental: Bjorken expansion • Theoretical: Gluon dominated plasma • Energy density • Transport coefficients (not a good measure for expanding medium) • Define the average for Bjorken

  30. Langevin Simulation of Heavy Quark Diffusion Input in a Langevin simulation of heavy quark diffusion H. van Hees, I.V., R. Rapp, in preparation • Drag coefficient: • Diffusion coefficient: Equilibration is imposed by Einstein’s fluctuation-dissipation relation: Radiative energy loss is dominantexcept for b-quarks and very small systems

  31. Transport + Quenching Approach Numerical results for heavy quark diffusion Results arepreliminary H. van Hees, I.V., R. Rapp, in preparation • The suppression and v2 are large when e-loss and q-resonance interactions are • combined • Normal hierarchy: c quarks are significantly more suppressed than b-quarks

  32. P xaP xbP’ P’ Hard Probes from Factorized PQCD Pd • Single and double inclusive hard production • in PQCD - applicable from photons to heavy • quarks X Pd / zd Pc / zc • Single and double inclusive hard production • in PQCD - applicable from photons to heavy • quarks X Pc Power laws: Quenching factor

  33. Jet cross sections: comparison to LO and NLO PQCD I.V., S. Wicks, in preparation • Good comparison to the shape at LO. • Meaningful K-factor • Even better comparison at NLO.

  34. P xaP xbP’ P’ Jets from Factorized PQCD • Single and double inclusive hard production • in PQCD - applicable from photons to heavy • quarks Pd X Pd / zd Pc / zc X Pc For jets: Caveat: parton-hadron duality • Jet cross sections are more inclusive and therefore more robustPQCD observables CDF studies: J.Collins, D.Soper, G.Sterman, Nucl.Phys.B (1983)

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