Exclusive Di-lepton and Photon Pairs in CDF

1. Exclusive Di-lepton and Photon Pairs in CDF SANDWICH Bread: MGA - Historical Introduction – relation to exclusive Higgs Meat: Andrew Hamilton: CDF detectors Trigger and data sample Selection of Exclusive Candidates Properties of Exclusive Candidates Bread: MGA: Implications for FP420: a) Lepton Pairs b) Photon Pairs

2. March 2001 : LOI to Fermilab PAC/Director to add precision Si trackers and fast timing quartz Cerenkovs in Roman Pots downstream of CDF to look for p+H+p at Tevatron. Now hep-ex/0511057 Did not become proposal: doubts about cross section, disturbance to Tevatron

3. “Fortunately there is a process that is very closely related to exclusive Higgs production, namely the exclusive production of two photons by gg-fusion through a quark loop. While in the Higgs case only the top quark loop is significant, in this case all quarks contribute, although the up-type quarks contribute a factor [Q^4 = 16] more than the down-type quarks. The crucial similarity is that in both cases the final state, H or gamma-gamma, is not strongly interacting. Therefore the non-perturbative parts of the process should be identical ...

4. ... some guesstimates on rates ... It happened more-or-less like that, but ~ 3 years later. No track veto! It needed a good student or post-doc. Andrew Hamilton started 2003 + Jim Pinfold, Bryan Caron, Beate Heinemann, MGA

5. Some Beyond-Standard-Model topics mentioned in LOI • hep-ex/0511057 and most relevant for FP420: • Extra generations: enhances gg  H cross section • Extended Higgs, CP-odd scalars, could be light, decays to photons. • top-Higgs, t-tbar bound state  tc. Large production in gg. • Color Sextet Quarks : Enhanced W-pairs • Graviton emission: enhancement in “empty” MM spectrum • Micro-Black Holes: Exotic/Hot/Democratic decays. Message: pp  p+H+p is “bread and butter”, but there is great potential in p+X+p for exciting BSM physics.

6. Theoretical developments: First theoretical calculation: Khoze, Martin, Ryskin, hep-ph/0111078 Eur.Phys.J.C23 (2002) p.311. This paper gave ~ 3fb for p+H+p at LHC. “It turns out that the event rate is too small: However ... what about M ~ 10 GeV, 20 GeV? Later, refined calculation: Khoze, Martin, Ryskin, Stirling hep-ph/0409037 to factor 3-5 • a few events in 100 inv. pb (effective, single interaction, luminosity) Good trigger crucial, careful study of detector noise crucial.

7. For two hard (pT > ~ 5 GeV/c) photons, color structure of process identical to exclusive Higgs production. Mostly u,c loops instead of mostly t loop. Q^2 lower. u,c

8. Andrew Hamilton: CDF Detector Getting the right trigger Looking for exclusive events Results

9. Luminosity at run start (end) now typically 150E30 (25E30). • Will not get a lot more effective (single event) luminosity. • Data  March 06 shut-down, ~ x 1.5 in events (?) + extended eta • Di-muon data: muon (pt > 1.5 GeV) + track (pt > 1.0 GeV) • (opp sign) + E&W gaps, 2.7 GeV < M(mu-tr) < 4.0 GeV • This will have Being analysed now (Bryan Caron, Jim Pinfold). Note different in 3 processes, and no High-luminosity di-muons? As at LHC. Needs new trigger. Calibrates FP detectors then calibrates central hadronic calorimetry : pp  p + X + p Calibrates Luminosity Counters (must do this with pile-up)

10. Khoze Martin Ryskin Stirling Needs good trigger (with forward vetos)

11. I believe this can only be measured with no pile-up, single interaction. These days are almost over at the Tevatron! Stores start ~ 150E30, dumped ~ 20E30 Can it be done at LHC? Effective luminosity for single interactions in 1st year ~ 100 pb^-1 ??? Trigger on 2 (EM>5,eta<2) * Fwd Gaps ... could get (KMRS) 60 x3-/3 events. Other reasons for single interaction running ... GAP physics Quite independent of exclusive Higgs, this is a precision pQCD process. Existence of exclusive implies that exclusive H must happen (if H exists! -- if not, exclusive WW/ZZ?)