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Exclusive Central Production in CDF (From talk to CDF CM, apologies for obvious to you)

Exclusive Central Production in CDF (From talk to CDF CM, apologies for obvious to you). where X is a simple state fully measured, and no other particles produced. (Cannot detect p/pbar, down beam pipe, but BSC → η = 7.4 empty). Motivation:

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Exclusive Central Production in CDF (From talk to CDF CM, apologies for obvious to you)

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  1. Exclusive Central Production in CDF (From talk to CDF CM, apologies for obvious to you) where X is a simple state fully measured, and no other particles produced. (Cannot detect p/pbar, down beam pipe, but BSC → η = 7.4 empty) Motivation: In CDF, sophisticated tests of QCD with large rapidity gaps Δy Looking forward to LHC: Interesting examples  If see h, H : Mass, width, spin J, C = +1, Couplings H – gg, … in a unique way, even if e.g. In CDF, 5 PRLs: (M, GeV range)

  2. A bit of history: To show that σ(p+H+p) was uncertain by a factor > 1000 in 2000 We absolutely needed some experimental input to home in on what to expect! * * * * Now measured in CDF

  3. Cleanest (no S.I.) but smallest σ KMR: 38 pb in our box). 2+1 candidates Clean, big σ: but M(c) small (non-pert) & hadron More perturbative, smaller theory uncertainty But σ ~ 1/500thχc. Also BR’s not known! See next slide. Big cross section, but least well defined (jets!) and largest background. ~ 100 pb for M(JJ) > 30 GeV Our 3 measurements are all in good agreement (factor “few”) with the Durham group predictions.

  4. Exclusive 2-Photon Production Phys.Rev.Lett. 99,242002 (2007) Khoze, Martin and Ryskin, hep-ph/0111078, Eur.Phys.J. C23: 311 (2002) KMR+Stirling hep-ph/0409037 Tevatron 36 fb H Claim factor ~ 3 uncertainty ; Correlated to p+H+p 3 candidates, 2 golden New data, Lower threshold, probable “observation” (Erik Brucken)

  5. CDF measurement of exclusive c  J/ψ + →μ+μ-  μ+ J/ψ μ- c γ & nothing else in all CDF -7.4 < |η| < + 7.4 Beam Shower Counters BSC: Scintillator paddles tightly wrapped around beam pipes. Detect showers produced in beam pipes if p or p dissociate. e.g. 8 + 10 counters If these are all empty, p and p did not dissociate (or BSC inefficient, estimated from data) but went down beam pipe with small (<~ 1 GeV/c) transverse momentum. - 50 m CDF central BSC (size greatly exaggerated!) 5

  6. Exclusive production (CDF) c has small pT, and so do muons: Trigger = 2 muons + BSC veto. pT(μ) >~ 1.4 GeV to escape calorimetry. M(μμ) <~ 4 GeV imposed by trigger rate (no prescale) Offline required μ+μ- or μ+μ-  and nothing else. Found most μ+μ- had no photon. Example: BSC1 (8 PMTs) 5.4 < |η| < 5.9 Hottest PMT (no int/int) 500 c 100 1000 counts

  7. arXiv:0902.1271 402 events Fit: 2 Gaussians + QED continuum. Masses 3.09, 3.68 GeV == PDG Widths 15.8,16.7 MeV=resolution. QED = generator x acceptance 3 amplitudes floating

  8. Some predictions for J/psi photoproduction: Machado,Goncalves 3.0 nb Motyka and Watt: 3.4 +- 0.4 nb Schafer & Szczurek ~ 2.8 nb Nystrand 2.7+0.6-0.2 nb Our result: 3.92 +- 0.62 nb e.g. Schafer and Szczurek: arXiv:0705.2887 [hep-ph] Take 3.0 +- 0.3 Our limits on O-exchange are close to, and constrain, theoretical predictions Y is much lower. Allow Pile-Up (x 10) More data (x 3) More Δy (x >4)

  9. Now allow photons: EmEt spectrum with J/ψ mass cut: Empirical functional form • 65 events above 80 MeV cut. • 3 events below (estimated from fit) • 4% background under J/psi • # = 65 +/- 8 MC also estimates only few % of under the cut (But CDF SIMulation is not reliable for such low ET)

  10. Events with EM shower Good fits to kinematics with only , if EM shower No photoproduced ψ’(2S) with EM shower > 80 MeV Confirms assignment

  11. Summary of Results M = 3-4 GeV/c2 90 nb (χ width) Durham No strong evidence for odderon

  12. PDG 2008 (latest): Could exclusive central production be a valuable lab for decays?

  13. Dimuons: Upsilon Region CDF Run II Preliminary Trigger: μ+μ- |η|<0.6 , pT(μ) > 4 GeV/c Inclusive Search for/measurement of photoproduction of Y, Y’ (not before seen in hadron-hadron) CDF Run II Preliminary Y(1S) Invariant Mass 0 associated tracks pT(μμ) < 1.5 GeV/c Y(2S) Status: analysis in progress. QED continuum check Y : cf HERA (we resolve states) Can we see ? Y(3S)

  14. Exclusive Upsilon(1S) candidateRun/Event: 204413/8549136 M ~ 9.4 GeV R-z, Muon hits But will allow P-U, (except for b Y +  search) Plugs, Miniplugs, CLC, BSC empty

  15. at Tevatron and LHC nb, “O.M.” Complex spectrum of radiative decays to Y(1),Y(2): Here just give DPE allowed states (J=0 >> J=2) ds/dy(KMRS,TeV) = 200 pb If BR = 4% (?) that’s 8 pb ->gY1 Cf ~ 10 pb for ds/dy(Y1) ds/dy(KMRS, LHC) = 600 pb If BR = 4% (?) that’s 24 pb ->gY1 cf ~ 30 pb for ds/dy(Y1) hep-ph/0403218 • Will not get good Y cross sections without knowing , and p-calibration screwed up. “Soft” photons important.

  16. Y: Predictions from Motyka and Watt arXiv:0805.2113 CDF Run II Phys.Rev.D78:014023,2008. Factor ~ 400 Other predictions: 12 +- 1 pb (Cox,Forshaw,Sandapan) ~12 pb (Klein & Nystrand) 0.8 – 5 – 9 pb (Bzdak,Motyka,Szymanowski & Cudell) HERA data not much help: Resolution confuses Y1,2,3, low statistics

  17. A. Szczurek: arXiv:0811.2488 ~ 30 pb

  18. QED γγ→l+ l- … and more so as M increases. CDF QED data: M(ll) = 40 – 76 GeV/c2 0.02 (rad) efficient. M(ee) = 10 – 30 GeV/c2 0.08 (rad) efficient. M(mumu) = 3 – 4 GeV/c2 0.34 (rad) efficient. is a good empirical fit to these QED data cuts. 0.13 for 8 – 9.2 GeV/c2 0.10 for 10.5 – 12 GeV/c2 How does resolution in compare CDF-ATLAS/CMS ?

  19. QED: pT(l+l-) cut dominated by detector resolution (so CDF not ~ CMS) True pT (Coulomb pair) < ~ 0.1 GeV/c. Looking at CDF data (small statistics in tail): M(e+e-) = 10-30 GeV/c2 pT < 1.6 GeV/c efficient. M(mumu) = 3 – 4 GeV/c2 pT < 0.3 GeV/c efficient. (- 3 outliers) M(ll) > 40 GeV/c2 pT < 1.1 GeV/c efficient pT <~ 1.0 GeV/c2 should be efficient for 8 – 12 GeV/c2 region (a priori).

  20. Photoproduction of vector mesons: larger J/psi psi(2S) pT <~ 1 GeV/c efficient ( - outliers) < ~ 0.65 efficient  <~ 0.22 for Y(1)

  21. Next steps: • Full data set (~ x 2-3). • Separate data in mass bands: QEDlow, Y1,Y2,Y3, QEDhigh, QED veryhigh. • Check all distributions & confirm cuts. • Simulate generation and CDF detector  Acceptance x efficiency • Cross sections {& no dependence on L(instantaneous)?} • CDF Lumi calibration has ~ 6%. Can these QED events help improve it?? (Marginal, but test bed for LHC) • The Y1 Y2 and Y3 photoproduction cross sections could be better than HERA (resolution & statistics). Odderon contribution? Information on dipole-proton scattering, g(x1,x2), S^2 etc. But: From “final” sample, select no pile-up clean events (~ 15%) Allow EM showers, look for:

  22. What about LHC and FP420 ? The best tests of • These can probably only be done with no pile-up, or • just possibly with just 1 or 2 min-bias events (? … could try) • Early days with low luminosity/bunch crossing: • <n_inel> < ~ 3 Exclusive 2+3 EM showers can give us these. These will practice calibration of FP420 spectrometers (momentum scale and resolution). Y’s higher rate than QED. Want forward pairs for acceptance.

  23. Key is good trigger in early: FORWARD SHOWER COUNTERS: FSC Level 1: 2 EM clusters > 4 GeV (E or ET?) + Forward gaps Little (<~ 4 GeV, or noise + x) E (ET?) in all hadron calorimeters. (In CDF this trigger worked with no prescale and no L2,L3.) Higher level: Cleaner forward gaps, 1 vertex Should get low rate (<~ 0.1/s?) with no prescale. Two muons with pT > 4 GeV/c and Forward gaps as well, want both Cross section at LHC Y, chi+b, QED,

  24. Y and FP420 at LHC Predictions from Motyka and Watt arXiv:0805.2113 Phys.Rev.D78:014023,2008. Large uncertainty in extrapolation. No gap survival probability! FP420 acceptance? 220 (most likely kinematics) is always much too small to see. Fortunately each xi(p) is known 420

  25. Photon “beams” radiated from electrons and protons LEP etc: e+e- (~ background free) HERA: e p (more background, little done) pp/ ppbar: Very high b/g … Seen in CDF e,p γ Tevatron as a  collider! PRL 102, 242001 (2009) Phys.Rev.Lett 98,112001(2007)

  26. M(ee) = 49.3 GeV/c2 |Δφ-π| = 6 mrad = 0.34 deg, pT(ee) = 210 MeV E not ET! CLC BSC M reach Tevatron >~ HERA, LEP !

  27. √s = 1.96 TeV Curves hand-drawn by me! No apologies for the quality! Can “read off” cross section For any M_min or M-range, and eta(max). Handy graph

  28. All our dilepton measurements agree with QED: So what? • It shows we know how to select rare exclusive • events in hadron-hadron environment • No other h-h cross section is so well known • theoretically except Coulomb elastic (inaccessible). • Possibly best possible Luminosity calibration at LHC e.g. • Outgoing p-momenta extremely well-known • (limited by beam spread). Calibrate forward proton spectrometers. • Practice for other γγ collisions at LHC: Luminosity calibration at LHC

  29. LPAIR cross sections at LHC (Emily Nurse): Have at Tevatron and LHC(14) (M in GeV): Useful look up.

  30. Exclusive Z production : CDF Search Allowed in SM (like V) but ~ 0.3 fb (Motyka+Watt) Could be enhanced by BSM loops Interesting?! -IP-Z eff.coupling. ZOOM IN to see how! 2.2/fb : 318K M > 40 GeV; 183K in Z window 82-98 GeV Require no other interaction, no additional tracks, all calorimeters in noise (E) 8 with BSC empty ~ record E() Search in “no-PU” events. Have 10 x data if PU allowed.

  31. Exclusive Di-Jets Phys Rev D77:052004 (2008) J GAP J JET Observed in CDF, QCD tests & related to p+H+p JET “Almost” exclusive di-jet, Two jets and nothing else Interesting QCD: gap survival, Sudakov factor Nearly all jets should be gg …. qq suppressed by M(q)/M(JJ) (Jz=0 rule) Gluon jet physics. 31

  32. Summary In p + p →p + X + p, t-channel exchanges only γ, {gg} (IP), or {ggg}(O) in L.O. (a) (b) (c) O has not been observed; we give best limit QED process (a) seen in e+e- and μ+μ-, M = 3 – 75 GeV/c2 In hadron+hadron, only CDF. Photoproduction (b) seen J/ψ, ψ’, Y(prelim), Z limit (only CDF) Exclusive gg →χc measured,  Excl.H must happen, σconstrained Exclusive γγ candidates, and exclusive JJ support some theoretical calculations, refute others. Best estimates now σ(p+p →p + SMH + p) ~ 1 – 10 fb @ LHC Feasible with v. high precision (space and time) p-detectors

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