wiki:SusyJets
Last modified 5 years ago Last modified on 04/19/12 09:52:41

Jet Radiation in SUSY events

People

  1. Johan Alwall
  2. Simon de Visscher
  3. Fabio Maltoni

Aim of the project

We study QCD radiation in SUSY events, such as gluino-gluino, stop-stop, stop-gluino processes. We use the MLM matching and verify/improve the results of Tilman, David and Peter, and in particular we investigate whether the extra hard jets in SUSY events are well described by the parton-shower, as it is usually claimed, or if matching gives a better description. We also study the matching in heavy tops events as a reference and the SM background needed in these kind of analysis. The SM samples will be used also for other applications.

Tools

Work

We have identified two phases:

  1. MC samples generation and validation
  2. Physics results and paper writeup

MC samples generation and validation

The strategy here is to first generate samples at the after-showering level to perform the validation. Once all samples are validated, we'll do the full Pythia-PGS simulation.

Generation
Standard Model Samples (Simon)

To get a faster generation we:

  • define a new model (smzerobmass), where the bmass is set to "Zero" in the particles.dat. This optimizes the flavor sum
  • We don't decay the Z, W+,W-, and tops. We'll let these particles be decayed by Pythia. In doing this we loose spin correlations, which, however are irrelevant for the multi-jet samples for this type of studies.
  • Not to generate the single particle samples for Z and W. These have a negligible impact on the multi-jet

configurations we are interested in.

  • In Pythia, we consider only decays of W into leptons (e, mu and tau) and also into neutrinos for Z.
SUSY and SM Samples

ProcessWebpagesection(s)LHE (on disks)PythiaMCPGS
1. gogo at 607 GeV (sps1a)n/a all okokok
1a. SC 1n/a4okokn/a
1b. SC 2n/a4okn/a
1c. SC 3n/a4okn/a
1d. SC 4n/a4okn/a
1e. QCUT x 2n/a3.1okn/a
2. gogo at 607 GeV with xqcut and QCUT / 2here 3.1 n/a
3. gogo at 607 GeV with scales divided by 2here 3 ok n/a
4. gogo at 607 GeV with scales multiplied by 2here3 ok n/a
5. gogo at 300 GeV 4 ok okokn/a
6. gogo at 1200 GeV 4 okok okn/a
7. sqsq at sps1an/a 4,5ok
8. sqgo at sps1an/a4,5ok
9. ulul at 607 GeVhere 3,4 ok ok n/a
10. ulul at 607 GeV with scales divided by 2here3 ok ok ok n/a
11. ulul at 607 GeV with scales multiplied by 2here 3 ok ok okn/a
12. ululbar at 607 GeVhere 3,4 ok ok ok n/a
13. ululbar at 607 GeV with scales divided by 2here 3 ok ok ok n/a
14. ululbar at 607 GeV with scales multiplied by 2here 3 okokokn/a
15. ttbarn/a3,5okok ok
15a. QCUT x 2n/a3,5ok n/a
16. ttbar with xqcut and QCUT / 2n/a3.1 n/a
17. ttbar with scales divided by 2here3 okok okn/a
18. ttbar with scales multiplied by 2here 3 ok ok ok n/a
19. W+4 jets biaisedn/a5 ok
20. W+3 jets biaisedhere5ok
21. Z+4 jets biaisedn/a5 ok

Physics results and paper writeup

Plots for the paper

Explanation of notation:

  • 4x2 runs means 4 unmatched, 4 matched runs with the different shower params
  • 4 params means with the 4 different shower params
  • decay jet #s means number of jets from decays
  • jet numbers means plot of number of jets above (say) 50 GeV in the events
FiguresectionProcess(es)DescriptionDone (plan)plot
1 2 n/a Feynman diagrams illustrating resonance double counting (3 plots) done
2 3.1 1,1e,2,15,15a,16 Standard validation plots: diff. jet rates 0,1,2 with QCUT, x2, /2 for pT- and Q2-ordered showers, for gogo and ttbar (4x3x3 plots) ?
3a 3.2 15 (4x2 runs),16,17 pT of 1st and 2nd extra jet in ttbar, unmatched and matched dep on shower params, scale dep. for matched (4 plots) 6-7/08 Pt_ttbar.eps
3b 3.2 1 (4x2 runs),3,4 pT of 1st and 2nd extra jet in gogo, unmatched and matched dep on shower params, scale dep. for matched (4 plots) 8/08? Pt_gogo.eps
4(7) 3.3 1,9,12 HTred and pTs, matched for gogo, ulul and ulul* 600 GeV (3 plots) 11/08 Htred.eps
5(6) 3.3 1,5,6 pT of 1st-2nd extra jet and HTred, matched for gogo at 300, 600, 1200 GeV (2x3 plots) 11/08 pt_300_600_1200.eps
6a(8) 4 1a (4x2 runs) HT(n),n=3,4,5(?) matched for gogo with decay jet #s, ETmiss unmatched and matched for sc. 1 (4 plots) 6-7/08 htcontrib-mockup.eps
6b(9) 4 1b (4x2 runs) HT(n),n=3,4,5(?) matched for gogo with decay jet #s, ETmiss unmatched and matched for sc. 2 (4 plots) htcontrib-sc2.eps
7(10) 4.1 1a (4 unm runs),12 HT(n),n=2,3,4 and jet numbers for unmatched gogo sc. 1 (4 params) and matched ululbar sc. 3 (2x4 plots) 12/08
8(11) 4.2 1d (4x2 runs) ETmiss unmatched and matched (1 plot) 12/08

For sec. 5 we should plot the most important quantities used in typical experimental analyses, such as ETmiss, HT(4), and what else? All after PGS.

-- Main.JohanAlwall - 05 Aug 2008

  • Htred.eps: Ht red for gogo, ulul and ululbar, as well as Pt of 1rst and second, all with and without matching
  • Htred.eps: Htred and Pt for gogo, ulul and ululbar, Pythia vs ME
  • htcontrib-sc2.eps: preliminary plot showing the contribution of decay jets to Ht and MET for scenario2

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