Diffractive Dijet Production with Leading Proton in ep Collisions at HERA

Transcription

1 Diffractiv Dijt Production with Lading Proton in p Collisions at HERA JHEP [arxiv: ] Radk Žlbčík Charls Univrsity Eric 015

2 Diffraction Th scattrd proton stays intact Exchang with vacuum quantum numbrs Pomron (from Rgg thory) Q Q 0 Q 0 Photon virtuality DIS photoproduction HERA: ~10% of low-x DIS vnts diffractiv Ep' q ( p p ' ) x IP = =1 bam q p Ep Fractional momntum loss of th scattrd proton t=( p p ' ) p T Four-momntum transfr at th proton vrtx

3 HERA p (90 GV) + ± (7.6 GV)

4 Larg Rapidity Gap Hadronic activity in forward part of dtctor Without hadronic activity in forward part of dtctor p Non-diffractiv vnt p Diffractiv vnt

5 Larg Rapidity Gap 1994 Nucl.Phys. B ηmax Without hadronic activity in forward part of dtctor p Diffractiv vnt

6 Dirct Proton Dtction Vry Forward Proton Spctromtr stations - 18 a m from intraction point 10 scintillating fibrs in on layr

7 Factorization in Diffraction DPDFs dtrmind from inclusiv masurmnt ar capabl to prdict rsults for othr, mor xclusiv procsss (dijts, D*), Collins 1997 D D i σ (p Xp)= parton f i (β, Q, x IP, t ) σ (β, Q ) i Partonic cross sction, procss dpndnt, calculabl within p-qcd Univrsal non-prturbativ DPDF D f i (β, Q, x IP, t ) DPDFs which oby DGLAP volution i σ (β,q ) Partonic cross sction

8 Hadron-Hadron Intractions Export of DPDFs from HERA to Tvatron.. γ*p Phys.Rv.Ltt. 84 (000) Singl-diffractiv / non-diffractiv Dijt cross sction pp KKMR [hp-ph/ ]: Multi-pomron xchangs introducd to tak into account s-channl unitarity Supprssion factor is introducd: HERA DIS 1 Tvatron ~0.1 Factorization brokn by factor around 10!

9 Diffractiv Dijt Production Photoproduction Dirct No photon rmnat x γ =1 (at parton-lvl) Dominant for high Q x γ= E jt1 T η jt1 jt T bam +E y E η zip pomron momntum fraction z IP = E η jt1 jt T bam p +E x IP E η x 1 Dominant for low Q γ-pdf introducd jt xγ photon momntum fraction jt1 T Rsolvd Photon rmnat Rsmbls hadron-hadron intractions (two-rmnants) whr th factorization braking was obsrvd jt LO diagrams! 9

10 Diffractiv Dijt Production DIS Photon ntrs dirctly into th hard subprocss On rmnant Factorization thortically provn (Collins 1997) zip pomron momntum fraction z IP = Q + M 1 Q + M X 10 LO diagram!

11 Motivation for th masurmnt Diffractiv dijt photoproduction masurd so far only by larg rapidity gap mthod H1 (010) ZEUS (008) [arxiv: ] [arxiv: ] σ DATA σ NLO =0.58±0.1(data )±0.17(thory ) σ DATA σ NLO =0.77±0.06 (data )±0.19( thory) KKMR [arxiv: ] KKMR [arxiv: ] S 0.5 S 0.6 Nw masurmnt with lading proton for diffractiv photoproduction and DIS as a rfrnc Th doubl ratios of data to NLO QCD prdiction for photoproduction and DIS introducd to bttr control xprimntal and thortical rrors 11

12 Masurmnt Stup Analysis basd on 006/07 +p HERA data, intgratd lumi ~30 pb-1 Lading proton masurd by proton spctromtr VFPS Photoproduction and DIS phas spacs idntical up to Q rang Jts dfind by k T -algorithm Photoproduction DIS ( Q < GV ) ( 4 GV <Q <80 GV ) VFPS + jts+ SPACAL VETO VFPS + jts + SPACAL positron Jt Jt SPACAL 0m VFPS p H1 SPACAL H1 0m VFPS p Jt1 ~ 3600 vnts Jt1 ~ 500 vnts Data unfoldd to th lvl of stabl hadrons using Tikhonov mthod 1

13 Diffrntial Cross Sction in z IP In photoproduction data supprssd by factor ~0.6 in comparison to NLO In DIS data satisfactorily dscribd by NLO 13

14 Diffrntial Cross Sction in x γ Q: Rsolvd photoproduction ( x γ <1 ) rsmbls hadron-hadron intractions Highr supprssion? A: No hint for highr supprssion for x γ <1 14

15 Doubl Ratio Doubl ratio of data to NLO QCD prdictions for photoproduction and DIS rduc data systmatic and thortical uncrtaintis (DATA / NLO)PHP =0.51±0.08(data)±0.03( thory) (DATA / NLO)DIS For QCD scal uncrtainty th scal varid simultanously in in photoproduction and DIS 15 by factor of ½ and

16 Diffrntial Doubl Ratios Doubl ratios ar within rrors constant 16 Dpndnc of th supprssion on E T of th lading jt not obsrvd

17 Dpndnc on Q 17

18 Summary Dijt diffractiv cross sctions masurd in two distinct Q rgions, photoproduction and DIS Supprssion factor in photoproduction about 0.5 stablishd Prvious H1 masurmnt confirmd by complmntary xprimntal mthod (dtction of lading proton) No hint of a dpndnc of th supprssion on x γ and ET of th lading jt 18

19 Backup 19