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Fix the "ill defined" ArrivalTime computed in mahi #28423

Open perrotta opened 5 years ago

perrotta commented 5 years ago

As sorted out from the review of #28366, the ArrivalTime resulting from the mahi HCal algo is ill defined and subject to unjustified fluctuations.

Quoting @mariadalfonso from the discussion in that PR:

"ArrivalTime is pretty much a ill undefined. It assumes that any fit discrepancy arises from the jitter of the pulse, which is not completely correct. For the Run2/Run3 there is no use of the recHit time() other than the beam-halo filter. For the Phase2 I honestly do not know how it is used: jenkins saw enough changes in the PF and jetMET quantities. I suspect is generically used for the barrel to exploit the new ECAL electronics.

There are HCAL long term plans for the redefinition of the arrivalTime (the physics case will be to target the LLP analyses). The possibilities we considered so far:

  1. M0: charge weights of the TS of the DIGI, problem in high PU
  2. DIGI/FIT hybrid: charge weighted of the TS of the DIGI after subtraction of the OOT pulses.
  3. M2 (fit E and time) = the time is explicitly fitted but the M2-fit was also abandoned because was not perfect.
  4. MAHI: add explicitly the fit for the time. For now we have an indirect estimate that any discrepancy of the fit is related to different arrival time of the pulse.

I never saw the correlation with a real MC signal displaced in time and this should be done before we use. In addition use the TDC from HE detector to validate the time with data."

perrotta commented 5 years ago

assign reconstruction

cmsbuild commented 5 years ago

New categories assigned: reconstruction

@slava77,@perrotta you have been requested to review this Pull request/Issue and eventually sign? Thanks

cmsbuild commented 5 years ago

A new Issue was created by @perrotta .

@davidlange6, @Dr15Jones, @smuzaffar, @fabiocos, @kpedro88 can you please review it and eventually sign/assign? Thanks.

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jpata commented 2 years ago

@mariadalfonso is this still open?

mariadalfonso commented 2 years ago

yes, it's still open. by now we also have a solution from @jaehyeok to replace this variable I will do a PRsoon (both CPU and GPU)

Note this does't modify downstream energy, it's an additional float unused for now but would be good to get in the Run3-MC as extra handle for LLP dedicated analyses (@abdoulline FYI

mandrenguyen commented 2 years ago

@mariadalfonso In light of #39227 we can now close this ancient issue, right?