ppg067 physics statements michael p. mccumber and barbara jacak august + september, 2006
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25 September 2006Michael P. McCumber & Barbara Jacak 3 Mechanisms for away-side modification Mach Cone Cherenkov Gluon-Radiation Wake Waves Medium-induced gluon radiation at large emission angles Damping of jet by strongly coupled medium (via AdS/CFT)TRANSCRIPT
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PPG067 Physics Statements
Michael P. McCumberand
Barbara JacakAugust + September, 2006
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25 September 2006 Michael P. McCumber& Barbara Jacak 2
Figure 3
rms increases with npartkurtosis decreases rapidly from near- gaussian values
away side peak dispacement is consistent with 0 in dAu & peripheral AuAu.rapidly increases to about 1 rad.
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25 September 2006 Michael P. McCumber& Barbara Jacak 3
Mechanisms for away-side modification
Mach Cone Cherenkov Gluon-Radiation Wake Waves Medium-induced gluon radiation
at large emission angles Damping of jet by strongly coupled
medium (via AdS/CFT)
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25 September 2006 Michael P. McCumber& Barbara Jacak 4
Mach Cones – Renk & Rupperthep-ph/0605330
Mach cone survives expansion!
Longitudinal flow → better Δφ signal from a Mach Cone
Data → large fractional of energy deposited in collective, propagating mode
Away Near→
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25 September 2006 Michael P. McCumber& Barbara Jacak 5
Mach Cones – Chaudhuri & Heinz
hydro simulations: assumelost energy instantaneously thermalized
No Mach cone produced
Large energy loss scenarios give “splash-back” signal
rejected by data
PRL97, 062301 (2006)
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25 September 2006 Michael P. McCumber& Barbara Jacak 6
Mach Cones – Jorge & Edward
Modified away side peak shape is due to propagation of a sound wave
Speed of sound intermediate between QGP (cs= 0.33) and hadron gas (cs= 0.2)
First order phase transition causes existence of region with cs=0. This would give a reflected wave, and 2nd peak at =1.4 rad
NP A774, 577 (2006) & hep-ph/0511263
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25 September 2006 Michael P. McCumber& Barbara Jacak 7
Mach Cones – Jorge & Edwardhep-ph/0511263
No clear (or even unclear) evidence for second peakin ppg032 result
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25 September 2006 Michael P. McCumber& Barbara Jacak 8
Run 4 AuAu
not here either…
(maybe in0-5% bin?)
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25 September 2006 Michael P. McCumber& Barbara Jacak 9
Cherenkov – Koch, Majumder, Wang
Cherenkov production has “a strong dependence on the gluon momentum” & will “disappear for high-energy gluons”
D values will “gradually” shrink as associated momentum is increased.
Not consistent with our data
PRL 96,172302 (2006)
Paul C’s AN
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25 September 2006 Michael P. McCumber& Barbara Jacak 10
Wake Waves – Ruppert, MullerExcite either a density wave or a plasma collective mode (plasmon)
Sub-sonic partons drag along a screening cloud as a wake (the response of plasma to color charge)
Super-sonic partons create Mach cone signal
If plasma is strongly coupled, high pparton excites plasma oscillations analogous to Cherenkov radiation(but it looks like Mach cone…)
PL B618, 123 (2005)
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25 September 2006 Michael P. McCumber& Barbara Jacak 11
Large angle gluon emission -- VitevPL B630, 178 (2005)
Predicted angles are typically smaller than observed.
pT dependence in central collisions (like the data)
Average scattering angle decreases with path length
This contrasts our centrality dependence!
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25 September 2006 Michael P. McCumber& Barbara Jacak 12
large angle gluon emission #2 Polosa & Salgado hep-ph/0607295
Look at symmetric & asymmetric gluon splittings (asym ~ like Vitev)pT trigger ~ pT associated restrict signal to a small number of splittingsSmaller qhat & larger radiated – gluons more collinear. So effects should disappear at smaller pTassoc at 62 than 200 GeV. can we say anything about this?
Vitev does opacity expansion, they use BDMPS
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25 September 2006 Michael P. McCumber& Barbara Jacak 13
AdS/CFTcorrespondence of gravity in 5D string theory & field theory similar (but not identical) to QCD → field properties in limit of super strong coupling.Friess, et al. (hep-th/0607022) stress tensor →wake of directional emission at p = several times the temperature
see alsoCasalderry &Teaney (nucl-th/0605199)
Liu, Rajagopal, Wiedemann (hep-ph/0607062) on qhat
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25 September 2006 Michael P. McCumber& Barbara Jacak 14
Figure 3
universal curve withNpart!
data imply:away side jetsplitting is aproperty of themedium, ratherthan the specificcollision system
successful modelsinclude strong mediumresponse to jet