1 / 15

Andrej Ficnar Columbia University

Non - conformal Holographic Model of Jet Quenching. Andrej Ficnar Columbia University. Andrej Ficnar, Jorge Noronha, Miklos Gyulassy. Quark Matter 2011 May 27 , 201 1. Outline. Motivation Holography AdS/CFT in a nutshell Conformal (non)invariance Bottom-up approach

debra
Download Presentation

Andrej Ficnar Columbia University

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Non-conformal Holographic Model of Jet Quenching Andrej Ficnar Columbia University Andrej Ficnar, Jorge Noronha, Miklos Gyulassy Quark Matter 2011 May 27, 2011

  2. Outline • Motivation • Holography • AdS/CFT in a nutshell • Conformal (non)invariance • Bottom-up approach • Fitting the lattice • Thermodynamics • Polyakov loop • Heavy quark energy loss and • Light quark energy loss Non-conformal Holographic Model of Jet Quenching | Andrej Ficnar | Quark Matter 2011 2/15

  3. Motivation • QGP behaves as anear-ideal fluid Luzum & Romatschke, 2008  Naturally implies strong coupling Non-conformal Holographic Model of Jet Quenching | Andrej Ficnar | Quark Matter 2011 3/15

  4. AdS/CFT in a nutshell • AdS/CFT conjecture: equivalence of (3+1)-dim SYM and type IIB string theory on • Holographic dictionary: • In this way, one can study strongly coupled gauge theories ( ) by studying classical two-derivative (super)gravity • Goal: understand finite temperature QCD using thermal SYMProblem: conformal invariance of SYM • trivial • vanishing trace anomaly • ... Maldacena, 1998 controls higher curvature contributions, want solution: take t’Hooft limit: controls quantum string effects, want Non-conformal Holographic Model of Jet Quenching | Andrej Ficnar | Quark Matter 2011 4/15

  5. Conformal (non)invariance Borsányi et al., 2010 • Lattice results show a significant violation of conformal invariance near • Follow the bottom-upapproach and break the conformal invariance: • From holographic dictionary: • Therefore, let’s look for gravity models with anon-trivial dilaton profile dual operator in the gauge theory (“at the boundary”) scalar field (dilaton) in the bulk Gubser et al., 2008 Kiritsis et al., 2008 Non-conformal Holographic Model of Jet Quenching | Andrej Ficnar | Quark Matter 2011 5/15

  6. Bottom-up approach • Task: construct an effective potential for the dilaton, which reproduces the expected phenomenology of the dual theory:induces a relevant deformation of the CFT: • Form of the potential constrained by phenomenology and numerical factors are fitted to the lattice data: • We require that the potential gives asymptotically ( ) - dual theory is conformal in the UV, but not asymptotically free ( finite)  applicability of the model restricted to close to fine tune of crossover interpolates between asymptotically AdS and a non conformal - gives determines Non-conformal Holographic Model of Jet Quenching | Andrej Ficnar | Quark Matter 2011 6/15

  7. Fitting the lattice • Solve EOMs using the following ansatz: • Use the speed of sound to determine the ‘critical’ temperature: Gubser & Nellore, 2008 Wuppertal-Budapest hotQCD Borsányi et al., 2010 Bazavov et al., 2009 Non-conformal Holographic Model of Jet Quenching | Andrej Ficnar | Quark Matter 2011 7/15

  8. Fitting the lattice • By fitting just , all the other thermodynamic quantities are automatically fitted, e.g. the trace anomaly • We will directly see how the trace anomalyaffects the energy loss of quarks Wuppertal-Budapest hotQCD Non-conformal Holographic Model of Jet Quenching | Andrej Ficnar | Quark Matter 2011 8/15

  9. Heavy quark energy loss • Quark of mass is dual to a string in the bulk stretching from a D7 brane at to the horizon • Trailing string ansatz • Dynamics of the string are governedby the classical Nambu-Goto action: • Energy loss given by the generalized drag force: Karch & Katz, 2002 Gubser, 2006 Herzog et al., 2006 D7 induced metric on the worldsheet coupling between the string and the dilaton Kiritsis et al., 2008 Increases monotonically with & in any holographic model Non-conformal Holographic Model of Jet Quenching | Andrej Ficnar | Quark Matter 2011 9/15

  10. Polyakov loop fixes the α’ • Polyakov loop is related to the free energy of a single heavy quark: • Therefore, we can actually constrain in our model by fitting the Polyakov loop to the lattice data Maldacena, 1998 Wuppertal-Budapest hotQCD α’- corrections are important and should be investigated Non-conformal Holographic Model of Jet Quenching | Andrej Ficnar | Quark Matter 2011 10/15

  11. Heavy quark energy loss Ficnar, Noronha, Gyulassy, 2011 Non-conformal Holographic Model of Jet Quenching | Andrej Ficnar | Quark Matter 2011 11/15

  12. Heavy quark RAA • computed in a dynamical, expanding plasma with Glauber initial conditions: • One should use the momentum (energy)of the string in the energy loss calculations - effective kinetic masses: charm cannot be treated as a heavy quark? ( ) Non-conformal Holographic Model of Jet Quenching | Andrej Ficnar | Quark Matter 2011 12/15

  13. Light quark energy loss • For light quarks, approaches so strings cannot trail anymore  falling strings • Maximum stopping distance: Gubser et al., 2008 Chesler et al., 2009 Non-conformal Holographic Model of Jet Quenching | Andrej Ficnar | Quark Matter 2011 13/15

  14. Light quark energy loss • Instantaneous energy loss seems to develop a Bragg peak at late times • Problems: • ambiguity where on the stringto evaluate the energy loss • depends heavily on initial conditions • Possible solution (work in progress): instead of momentum loss ( ), look at the momentum of the half of the string: Non-conformal Holographic Model of Jet Quenching | Andrej Ficnar | Quark Matter 2011 14/15

  15. Conclusions and Outlook • Gauge/string duality gives us means to address the violation of conformal invariance near and see how the trace anomaly affects the energy loss • In this model, the energy loss of heavy quarks is a prediction • forRHIC & LHC decreases monotonically with • More ambiguities in the treatment of light quark energy loss • Maximum stopping distance: & - dependent power • Things to do: • Investigate different dilaton potentials • Theoretical band on heavy quark • Consistent light quark energy loss & Non-conformal Holographic Model of Jet Quenching | Andrej Ficnar | Quark Matter 2011 15/15

More Related