EA propagation: meeting minutes 5/21/10

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M.Lamont, M.Ploszkon, A.Daniel, P.Khetarpal, H.Avakyan, T.Mineeva, A.Accardi, J.Gilfoyle, A.Majumder, P.Nadel-Turonski

Next Meeting: Thu, May 27, at 1pm

Talk on jets

M.Ploskon gave a detailed talk about jet recontruction. Check his slides. Here I summarize the discussion.

He empasized that a "jet" is in fact defined by the jet reconstruction algorithm adopted, and discussed the general requirements: infrared and collinear safety, ease of implementation in data analysis and theoretical computations, minimal sensitivity to hadronization.

Different jet algorithms have different strengths, in particular regarding sensitivity to the underlying event (soft particles not part of the jet) and to hard gluon radiation. They also recombine tracks in different ways. The choice of algorithm is in part dictated by the observables under study: for example for Z' searhces at LHC one wants to recombine the hardest tracks first, and the kT algorithm is preferrable; for Higgs searches also teh SiScone algortihm is fine. In Heavy-Ion Collisions, robustness regarding teh background is imperative, so that the kT-algorithm is indicated.

How to chose the jet "resolution parameter" depends on our aims. For example, if we are studying jet rates vs. resolution as test of energy loss, STAR has noticed that at small resolution the reconstruction becomes sensitive to details of hadronization, so one has a lower limit. For jet cross section measurements, one wants the largest resolution that does not include too much background, to be sure one is reconstructing most of the parent parton moentum.

Background subtraction and jet energy resolution are possibly important also in e+A, where the final state multiplicity is low. Careful studies are needed in order to quantify their effect.

In the last part, Mateusz discussed a few jet observable, including:

  • variation of resolution parameter to study energy loss
  • sub-jets
  • ...

Mateusz and Abhijit agreed to write a wiki page on relevant jet observables in p+p and A+A, so we can all start thinking about nice observable adpted to the e+A case.

As soon as we have Q-Pythia for cold matter, we will be able to start looking at Jets at the EIC.

Update on cold Q-Pythia

Aji and Alberto are discussing the details of the implementation of cold nuclear matter for e+A collisions in Q-Pythia.

New wiki pages on light and heavy flavors

Please check the new wiki pages on light and heavy flavors that Raphael started - just follow the links on the Observables page