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Meeting Minutes

| 11/16 informal meeting | 17 September 1998 |corrections to 17 September mintues | Questions from November Atlas Week |


11/16 September 1998 to do list

An informal meeting was held in the CERN canteen this morning. We agreed on the following:

  1. TDR
    1. Protvino and Dubna are interested in a variety of new physics topics (Protvino, through current progress in FCNC production and decay.Dubna in 4th family possibilities.)
    2. Dubna and Vancouver are interested in Vtb and cross section measurement (I think that Dubna is interested in concentrating on gluon-fusion and Vancouver on the s-channel processes)
    3. Vancouver and MSU are interested in polarization topics
    4. We agree that the next atlas week, last week of February, is too near the final deadline for the TDR to be able to reliably make decisions. Therefore, it will probably be necessary to meet before February.
  2. Calculations
    1. All groups are calculating various processes:
      1. Protvino: generation of Wt recently (in pythia), gluon-fusion (private matrix elements), s-channel (private matrix elements), ttbar (private matrix elements), Wbbbar background (private matrix elements)
      2. Dubna: generation of gluon-fusion (in pythia), ttbar (in pythia), and Wjj (in pythia)
      3. Vancouver: analysis of onetop ntuples for primarily s-channel and ttbar
      4. MSU: generation of gluon fusion, s-channel, Wbbbar, ttbar, and Wt (recently).
    2. MSU is interested in generating a single top process with the full atlas detector simulation for eventual trigger simulation studies. John said, "write me a letter and ask". In discussion about this, it was learned that most (all?) of the ttbar full simulation is for | eta | < 3.2 for jets...for trigger studies, this needs tobe expanded to the entire detector.
    3. Background. Essentially, nobody knows what the right level is for W+njets and/or W + bbbar + njets processes. This will require some Executive Decision which should be common to the Top Group, as well as the Higgs group (Wbbbar). John will check in some big-shot meeting which is happening tonight (?).
  3. To Do List
    1. Single top members are supposed to send to Chip their January schedules, either saying when they cannot meet or when they prefer to meet at CERN during the last two weeks of January for a brief period.
    2. People who have calculated cross sections should send them to Chip asap for review on Wednesday. These should be the generated cross sections, not theory values adopted for comparisons.
    3. People who have calculated distributions should make plots according to the following convention:
      • all enegies/ momenta: 0-250 GeV
      • all rapidities: -7 - +7
      • all plots normalized to 1.0
      • 100 bins
      • 1 plot per page
  4. We will meet again Tuesday morning, 17 November, in the CERN canteen at 10AM to compare plots and plan final single-top presentations for Wednesday.

 

17 September 1998

Hi

A group of us attending the September Atlas Week who are interested in Electroweak top quark production met informally this afternoon to compare notes and begin working toward the TDR chapter. These minutes are to establish what we discussed and to insure that I have proper email addresses and names spelled correctly. I would appreciate a quick REPLY to this note to let me know that you got it and to tell me if you see any errors or ommissions in the followingdistribution list:

(see below)

marina.cobal@cern.ch
parsons@nevis.columbia.edu
Stefano.Lami@cern.ch
mehdiyev@sunse.jinr.ru
lefebvre@uvic.ca
Dugan.O'Neil@cern.ch
slabospitski@mx.ihep.su
koukhtine@cern.ch
pineiro@pa.msu.edu
abolins@pa.msu.edu
yuan@pa.msu.edu

Present in our informal discussion were: Cobal-Grassmann, Lami, Mehdiyev, Slabospitski, Koukhtine, and Brock. 1. I proposed an outline for our part of the TDR which was slightly modified in discussion (add [4.5.1.6] as a prefix to all sections):


[4.5.1.6] EW Top Quark Production - introduction

[].1 Physics Measurements
.1.1 cross section(s), top width and V_tb
.1.2 polarization of top and W
.1.3 CP violation
.1.4 New physics
.1.5 others?

.2 Generators

.2.1 pythia and modified pythia
.2.2 onetop (Yuan, et al.)
.2.3 madgraph (Willenbrock, et al.)
.2.4 comphep (Belyaev et al.)
.2.5 others?

.3 Signal and Background separation strategies

.3.1 backgrounds
.3.2 gluon-fusion reaction
.3.3 Wt process
.3.4 W* process

.4 Experimental considerations

.5 Theoretical considerations and uncertainties

[4.5.1.6].6 Conclusions and future plans
------------------------------------------------------
(
top)


I think that I heard agreement on the following points:

2. the standard ATLFAST ntuples will be the common "language" for signal and background montecarlo generation

- some analyses may include parton-level ntuples of the original hard processes, but they will be separate ntuples and not subject to standarization

3. We will likely create a central directory at CERN where the ntuples will reside. One should be able to rely on those data sets as the most recent versions, within their classifications. Those supplying ntuples are obligated to produce documentation to accompany the files noting program origination, algorithms, versions of standard software, notes, etc. I think it would be ideal if this documentations would be in the form of a web page which could be local to your institution. If you would rather supply TEXT, I'll convert it to HTML and post it.

- marina was going to check on available disk storage space and let me know if we need to supplement it. (The ATLFAST ntuples are large.)

4. I will produce a central web site which will point to each of the separate documents above as well as other pieces of useful information.

5. Various folks have produced W+jet background calculations. We agreed that it may prove important to have multi-jet, hard events passed through to ATLFAST, but that until that exists, pythia will be sufficient. Marina is going to revisit an atlas note on this subject that she co-authored with Pisa colleagues [ATL-PHYS-96-093...right, Marina?] (wrong...see below)

- In addition to standard W+jets calculations, it may prove useful, to have MC data sets in which heavy quarks are forced in each event.
- I think that we should freeze background calculations relatively soon so that calculations don't have to be redone.

6. We agreed that we should establish some benchmark distributions in order to compare calculations.

7. Stephan (wrong, Antonio!...see below) reported a problem with the pythia example in the ATLFAST documentation. The card, MSTP(48) is set =1, which results in W decay without proper polarization (just straight phase space?). The default is =2 and this card should be commented out. This is apparently the determination after a recent frustrating period of trying to understand the odd decay distribution.

8. I know of the following work which could be submitted soon:

- Rashid has pythia-generated gluon-fusion events with a slimmer ATLFAST ntuple format. He also has background calculations. - Serge has pythia-generated gluon-fusion events with a different implementation of pythia.
- For this meeting, Beatriz Pineiro generated ntuples based on the onetop code, through to the standard ATLFAST ntuple format.

9. I believe I heard interest in the following physics/calculations:

- gluon-fusion: Rashid
- Wt and W*: Serge ( I believe that the Victoria group is also interested in V_tb from W*? Please correct me if I'm mistaken.)
- polarization: MSU
- the "double-counting problem": MSU

(top)

10. To do, immediate (~1-2 weeks)

a. Establish central site for ATLFAST ntuples. *Marina and Chip*
b. Individuals should complete calculations in standard form and prepare documentation. *Rashid, Serge, MSU*
c. General EW Top quark web site. *Chip*
d. Folks should commit to specific writing responsibilities according to the outline above. *Group*

- The writing will eventually be submitted to me in ASCII form, with LaTeX formulas. I will test my version of Framemaker 5.5 and try to hand a file to Marina to see if we can go from Mac to Unix. If okay, I'll insert group's work into the TDR template for our sections. If not, I'll forward the whole mess to our Top Leaders with the request that we switch to LaTeX some day.
- We agreed that we will work toward a complete document, distilling it later to the few pages that we will be allowed.
- In one week, I'll send back to the group your stated commitments for writing, maybe with suggestions if there are big holes.

11. To do, longer term (~4-6 weeks)

a. Background decision..freezing our background plans for the TDR (I'm guessing that if we had to use pythia for the TDR, it would be okay for single top physics...?) I would suggest using the onetop-generated results forthe ttbar background in order to take advantage of the full density matrix results.
b. Calculation comparisons
c. Fine-detail outline with figures and captions (!) as mandated by the Atlas management for 10/31. As that date approaches, we can figure out just what to do.

12. To do, very long term (~few months)

a. Establish real Signal-Background separation strategies for each reaction. Of course, there may be multiple approaches, but they should be fully documented in order to appear in the TDR. I think that John and I will be attending the Fermilab top quark workshop... We will make an effort to get transparencies, if they are not posted on the web.

Please tell me if I've left something out or made mistakes. We should obviously plan to meet again during the November Atlas Week. I'll be in touch with you in the meantime as progress occurs.

Regards,

Chip

------------------------------------------------------------------------
Raymond Brock 207 Physics & Astronomy Bldg | Professor of Physics
Dept of Physics & Astronomy | and Chairperson
Michigan State University |
East Lansing, MI 48824 | brock@chip.pa.msu.edu
..................................................................
http://www.pa.msu.edu/~brock/chips_homepage_hot.html
Dept office:(517)353-8662
HEP office:(517)353-1693 Fax:(517)353-4500
fermilab office:(630)840-8795 home:(517)351-4287
------------------------------------------------------------------------

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Corrections to 9/27/98 minutes

There were a few corrections to the minutes:

1. I misidentified Antonio Lagatta as "Stephano Lami". I apologize to Antonio and thank Marina for letting me know.

2. I failed to include Sylvain Negroni as a member of this group. He is at Marseille and is working on R-parity violating SUSY as an exotic source of single top quarks.

3. I believe that I misidentified the ATLAS note that was relevant to W plus jets production, specifically regaring the VECBOS generator. It is correct on the publications page.

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Questions from November Atlas Week

soon.


last modified: Thursday, December 10, 1998

Maintained by Chip Brock
Raymond Brock, Professor of Physics and Chairperson, Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824,