Les Houches
2023 Session
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- Use of wiki pages and slack. Wifi access/set-up.
- Important info about bus, lodging, facilities.
- Bulletins.
Wikis of Previous sessions
Les Houches Themes
(Lyrics and Music)
(Lyrics and Music)
This is an old revision of the document!
a.k.a. Hunting the White Whale of Jet Substructure
Link to GitHub repository: https://github.com/gsoyez/lh2015-qg
* original discussion from 2015-06-02 Generic commentes: ------------------ - ill-defined but OK in the eikonal limit one speaks of quark or gluon-enriched samples - we need an operational definition defined by final-state. e.g. rapidity correlation or shape separate measurement v. interpretation - be worried about the process dependence and the detector effects (MC study v. behaviour in data) - try to speak of a S/\sqrt{B} improvements rather than q/g discrimination [this is also related to the definition of a hadronic W] - can we find a better naming convention? Suggestion: quark-gluon enrichment - Why? Is there a killer app? use q/g as a piece of an analysis general recipe v. optimal analysis - can we use flavoured jet algorithms? - FSR issues (pointed out by Jesse in the introductory talk) related to tuning gluon jets in MC related to colour correlations with ISR [ISR should be sensitive to large angle => see some process-dependence] [FSR should be fimen at small angle => see universality] - Look at hard core v. wide angle. - Experimental results . ATLAS v. CMS: ATLAS suggests beta->0 is not effective CMS says pTD is good . analytics suggest low beta works best . ATLAS sees a large process dependence . is there a connection with ISR? see http://arxiv.org/abs/1405.6583 Appendix A. - Spin information. . is it in the MC? [yes] . does it help or hurt? - g \to qqbar v. g \to gg does it help or hurt - quark v. heavy flavour? Use cases: ---------- - VBF tagging - SUSY multijet is q-enriched - pileup jet rejection (stochastic?) - enhance W/Z/t/H in boosted regime Concrete study(ies) for Les Houches? ------------------------------------ Ideal result: recommendation for experiment for observables that carry info, defined in the final state and define q/g and eventually useful for MC tuning (check the systematics) - A14 tune uses jet shape this brings alphas down Q: what happens to LEP? - 1st study: do we understand FSR modelling? . take e+e- to qqbar and gg . vary energy and jet radius . vary shapes . ROC v. mutual info I(T;A) . use as many MC options as possible shapes: (kappa,beta)=(1 ,0.5) (1 ,1) (1 ,2) (0 ,0) (2 ,0) (0.5,0.5) (0.5,1.5) + ellipticity (+ pull)? + Psi(r) + check Gallicchio and Schwarz . tau21 of ECF(2,3) + ?? on full event or only on tracks? questions: choice of axes (recoil) sum or sum over pairs? . for hadron colliders: look at dijets W/Z/gamma+j ttbar . use groomed jets use soft-drop beta . question of robustness v. performance (including process dependence, pileup, low pt v. high pt) Tasks: ------ - tool writing (jet shapes) use FJ, Rivet professor? [Jesse, Gregory, Deepak] [+Andy B??] - MC for e+e- HERWIG, Pythia, SHERPA [hook Franck, Mark?], VINCIA, ... + options [Peter S, Andrzej] - MC for pp above, +PU, VBF [Peter L.]