What about the chiral phase transition or Where does mass (hadronic) come from?. Do we understand the relationship between the chiral and deconfinement transitions? Can we see the ? Are there reliable calculations of mass? (see duality) Shift up, shift down, broadening, exist above T c ?
e+e- e+e- e+e- e+e- e+e-
Signal should increase with centrality
Signal should be enhanced at low pT
Central- “High” PT
Central- “Low” PT
Raw e+e- inv mass
Combinatorial dalitz background
After background subtraction
40% “duty factor”
Hot vector mesons from fireball
“ordinary” Vector mesons
High pt (>0.8GeV)
Low pt (<0.2 GeV)
From inside the fireball
We should be able to identify this if the enhancement is as strong as predicted. (remember change bin by 5)
But is it a “hot qgp” or a cold hadron gas?
Low pt central
High pt peripheral
Charm- low pt central
Charm-high pt peripheral
In the case of a hadron gas, though strongly enhanced the should have its ordinary width. The and will be separable.
In the case of “in medium” effects both the and will be strongly broadened.
Probably not next run
Cold Hadron Gas
Mee 109 central events pt<0.2 Gev
w/ 90% datitz
(Pe > 200 MeV/c)
dalitz/conversion has ~ zero opening angle
Must provide sufficient Dalitz rejection (>90%) while preserving the true signal
dpT/pT ~ 0.02
Note strong broadening of
Red- “in medium”