Presentation on theme: "1 Exclusive DPE Higgs production at LHC Marek Taševský (Physics Inst. Prague + Univ.Antwerp) ISMD 2005 - Kroměříž (Czech Republic) 15/08 2005 1. Comparison."— Presentation transcript:
1 Exclusive DPE Higgs production at LHC Marek Taševský (Physics Inst. Prague + Univ.Antwerp) ISMD 2005 - Kroměříž (Czech Republic) 15/08 2005 1. Comparison of DPEMC, ExHuMe and EDDE at parton, hadron and detector levels 2. New Roman Pot acceptances 3. Event yields for H->WW
2 The Large Hadron Collider (LHC) PP collisions at s = 14 TeV 5 experiments 25 ns bunch spacing 2835 bunches 10 11 p/bunch Design Luminosity: 10 33 cm -2 s -1 -10 34 cm -2 s -1 100 fb -1 /year 23 inelastic events per bunch crossing TOTEM In LEP tunnel (circonf. 26.7 km) Planned Startup: Summer 2007
3 The CMS experiment o Tracking o Silicon pixels o Silicon strips o Calorimeters o PbW04 crystals for Electro-magn. o Scintillator/steel for hadronic part o 4T solenoid o Instrumented iron for muon detection o Coverage oTracking 0 < | | < 2.5-3 o Calorimetry 0 < | | < 5 A Huge enterprise ! Main program: EWSB, Beyond SM physics…
4 Roman pot acceptances - t=10 - 1 -t=10 -2 High * (1540m): Lumi 10 28 -10 31 cm -2 s -1 >90% of all diffractive protons are seen in the Roman Pots. Proton momentum measured with a resolution ~10 -3 Low *: (0.5m): Lumi 10 33 -10 34 cm -2 s -1 220m: 0.02 < < 0.2 300/400m: 0.002 < < 0.02 (RPs in the cold region/FD420 under discussion in CMS/ATLAS) TOTEM (ATLAS) FD420
5 For the first time at a collider large acceptance detector which measures the forward energy flow 1 day run at large beta (1540m) and L=10 29 cm -2 s -1 : 100 million minimum bias events, including all diffractive processes >90% of all diffractive protons are detected microstation at 19m ? RPs Total TOTEM/CMS acceptance ( * =1540m) CMS/TOTEM is the largest acceptance detector ever built at a hadron collider TOTEM+CMS T1,T2 Roman Pots Charged particles Energy flux CMS/TOTEM Study
6 Diffraction at LHC: PP scattering at highest energy Soft & Hard Diffraction < 0.1 O(1) TeV “Pomeron beams“ E.g. Structure of the Pomeron F( ,Q 2 ) down to ~ 10 -3 & Q 2 ~10 4 GeV 2 Diffraction dynamics? Exclusive final states ? Gap dynamics in pp presently not fully understood! proton momentum loss measured in RPs
7 H gap -jet Double Pomeron Exch. Higgs Production Exclusive DPE Higgs production pp p H p : 3-10 fb Inclusive DPE Higgs production pp p+X+H+Y+p : 50-200 fb p p Mh² measured in RP via missing mass as ξ1*ξ2*s bb: Jz=0 suppression of gg->bb bg | WW: bg almost negligible E.g. V. Khoze et al M. Boonekamp et al. B. Cox et al. … V.Petrov et al. Advantages of Exclusive: bb: We need a L1-trigger of “central CMS+220 RP” type. Central detector is issue as CMS is not designed for low Et physics. Under study by CMS-Totem L1-tr. group WW: Extremely promising for Mh>130 GeV: no trigger problems and a better Mh resolution for higher Mh. (Wˉ) (W+)
8 DPE Higgs event generators 1.DPEMC 2.4 (M.Boonekamp, T.Kucs) - Bialas-Landshof model for Pomeron flux within proton - Rap.gap survival probability = 0.03 - Herwig for hadronization 2. EDDE 1.2 (V.Petrov, R.Ryutin) - Regge-eikonal approach to calculate soft proton vertices - Sudakov factor to suppress radiation into rap.gap - Pythia for hadronization 3. ExHuMe 1.3 (J.Monk, A.Pilkington) - Durham model for exclusive diffraction (pert.calc. by KMR) - Improved unintegrated gluon pdfs - Sudakov factor to suppress radiation into rap.gap + rap.gap survival prob.=0.03 - Pythia for hadronization All three models available now in the fast CMS simulation!
9 Difference between DPEMC and (EDDE/ExHuMe) is an effect of Sudakov suppression factor growing as the available phase space for gluon emission increases with increasing mass of the central system Models predict different physics potentials !
13 New Roman Pot acceptances for β*=0.55m Update of RP acceptances for recent LHC optics V6.5 (V.Avati and K.Osterberg, Totem Note 05-2) V6.5 V6.2 β*=0.55m 0.5m x*=500μm 0 μm Beam X-angle=142 μrad 150 μrad Proton trajectories simulated with MADX These acceptances recently put in FAMOS.
25 Excl.DPE H->bb: Event yields per L=30 fb-1 Selection cuts at detector level for mh=120 GeV: 0) Both protons accepted in one of two (220,420) RP stations 1)N jet > 1 2) 45 30 GeV 3) | η j1,2 | < 2.5 4) | η j1 -η j2 | < 1.8 5) 2.8 < | φ j1 -φ j2 | < 3.48 The cuts still 6) M j1j2 / M tot > 0.75 being optimized 7) M j1j2 / M miss.mass > 0.8 8) N part (3 < | η | < 6) = 0 9) 117 < M miss.mass < 123 GeV 10) Both jets b-tagged (~40% total efficiency) Generator σ xBR[fb] Acceptance gg->H->bb BG(gg->bb;gg->gg) DPEMC 2.0 50% EDDE 1.3 46% UNDER STUDY ExHuMe 1.9 57%
30 Summary - Recent versions of DPEMC, EDDE and ExHuMe generators as well as new RP acceptances available in CMS fast simulation - Working on optimizing the selection cuts for H->bb and H->WW channels. The H->WW channel looks promising for Mh>130 GeV. Unlike for H->WW, the L1-trigger and background for H->bb are issues and still need a lot of work. A common CMS-TOTEM L1-trigger working group established and studying this problem intensively - Hot topic these days: Which model gives the best description of data??? The problem is that the only data available are those of Rjj distr. from CDF. More to come soon…