Event shape analysis in diffractive DIS (past and future) Alice Valkárová Charles University, Prague 1/2/2019 Diffractive meeting, Antwerpen 2005

Diffractive meeting, Antwerpen 2005 Definition of thrust For each event obtain the information on: Orientation w.r.t. photon pomeron axis Shape given by thrust T Thrust finds the direction in CMS along which the energy flow is maximal ½ < T < 1 isotropic fully aligned qq system 1/2/2019 Diffractive meeting, Antwerpen 2005

Diffractive meeting, Antwerpen 2005 Motivation The thrust is the possible tool to distinguish between two-jet (qq) and three-jet (qqg) configurations. It was very useful also in the case of gluon discovery. The important quantity is also the pt of the thrust axis w.r.t. the interaction axis pt γ pomeron Thrust axis pt was not measured by ZEUS! 1/2/2019 Diffractive meeting, Antwerpen 2005

Diffractive meeting, Antwerpen 2005 The past H1 publication: Thrust Jet Analysis of Deep-Inelastic Large-Rapidity-Gap Events C.Adloff et al.,Eur.Phys.J. C1 (1998) 495-507 1994 data with 2 pb-1 using rapidity gap method ZEUS publication: Event Shape Analysis of DIS Events with Large Rapidity Gap at HERA J.Breitweg et al.,Phys.Lett. B 421 (1998),368 1994 data with 2.6 pb-1 using of Mx metod ZEUS publication: Properties of hadronic final states in diffractive DIS at HERA S.Chekanov et al.,Phys.Rev.D65,052001 (2002) 1997 data with 13.8 pb-1 using LPS spectrometer 1/2/2019 Diffractive meeting, Antwerpen 2005

Diffractive meeting, Antwerpen 2005 ep diffraction & e+e- Thrust from H1 paper 1998 Thrust in ep diffraction was found to be smaller than in e+e- thus indicating larger fraction of higher parton multiplicities in ep than in e+e- It was not confirmed by ZEUS paper from 1998! 1/2/2019 Diffractive meeting, Antwerpen 2005

Diffractive meeting, Antwerpen 2005 ZEUS paper from 2002. Using of LPS helped a lot…. Diffractive system is more spherical than in e+e- interactions, H1 results confirmed. 1/2/2019 Diffractive meeting, Antwerpen 2005

Diffractive meeting, Antwerpen 2005 MC’s development The significant improvement of RAPGAP generator from 1997 Old comparison from the paper HZTOOLs-RAPGAP 3.01 1/2/2019 Diffractive meeting, Antwerpen 2005

Diffractive meeting, Antwerpen 2005 MC’s development Pt<1 GeV and Pt>1 GeV Old comparison from paper New RAPGAP-HZTOOLs 1/2/2019 Diffractive meeting, Antwerpen 2005

Distributions of pt2 in Mx intervals New RAPGAP-HZTOOLs, more steep distributions Fitted data in Mx intervals, slope is close to ∝1/pt2 1/2/2019 Diffractive meeting, Antwerpen 2005

Fraction of events with pt2>1GeV2 New comparison Old comparison (1997) Not much improvement…….. 1/2/2019 Diffractive meeting, Antwerpen 2005

Fraction of events with pt2>3 GeV2 Old comparison (1997) New comparison Definitely not an improvement.. 1/2/2019 Diffractive meeting, Antwerpen 2005

Diffractive meeting, Antwerpen 2005 Summary & proposal with new RAPGAP thrust data from 1994 are described better than previously distributions of pt2 of thrust axis w.r.t.axis of interaction are still poorly described – there is not enough of events with higher pt in MC use new data (lumi 50 times larger )with the information from VFPS (non-diffractive background suppressed) to analyze pt2 distributions much more thoroughly, (in dependence on W and other variables). 1/2/2019 Diffractive meeting, Antwerpen 2005

Diffractive meeting, Antwerpen 2005 RAPGAP direct and resolved, ntuples used for Kamil’s jet analysis Pt>5 GeV, -3.<η<0. Non-diffractive, Q2>2 GeV2 Azimuthal angles of first and second jet in γp CMS 1/2/2019 Diffractive meeting, Antwerpen 2005

Diffractive meeting, Antwerpen 2005 HZTOOLs – RAPGAP 3.1 BGF 350 k events Diffraction Analysis of F.P.Schilling 4<Q2<80 GeV2, CDF cone, pt>4GeV -3.<η<0. in HCMS Jets on hadron level 250 kevents 200 kevents 1/2/2019 Diffractive meeting, Antwerpen 2005