1. Diffractive Higgs Production at the Tevatron and LHC http://www.pomwig.com Do we all disagree, and, if so, why? How sensitive are the predictions to the parameters of the pomeron trajectory? Can we check the LHC predictions in Run II? Phys. Lett. B 540 (2002) 263-268 Brian Cox, Jeff Forshaw and Beate Heinemann Workshop on low x physics, Antwerp 2002

2. WHAT IS POMWIG ? No doubt that Ingelman – Schlein works at HERA Pomwig uses measured structure functions and flux from H1 OR user defined structure functions / flux PLUS all HERWIG hard sub-processes / hadronisation etc.

3. What do we calculate? Khoze, Martin & Ryskin, hep-ph/0207313 “Inclusive” (Central-inelastic) process p+p p + gap + H + X + gap + p

4. What do we calculate?

5. Results CDF measured   44  20 nb S 2 = 0.1 S 2 ~ 0.02  ~  6  fb Enberg ~ 2 fb

6. Higgs cross sections IP + IR,  IP = 1.20,  IR =0.57 (POMWIG defaults) ,    M H = 115 GeV

7. What effect does the intercept have? H1 fit 2

8. S 2 = 0.02 S 2 = 0.1 (CDF data) Theory: S 2 = 0.05 Khoze, Martin & Ryskin, hep-ph/0207313 fb Are these diagrams as large a contribution as KMR calculate?

9. Can we see the exclusive contribution in the data? Exclusive limit ~ 3.7 nb CDF Phys. Rev. Lett 85 4215 (2000) Exclusive calculation ~ 1 nb (Khoze, Martin & Ryskin, hep-ph/0111078, 0006005) Appleby & Forshaw, Phys.Lett.B451 108-114 (2002) POMWIG does well at differential distributions Mass dist. similar (KMR hep- ph/0207313)

10. Exclusive vs. C.inel Cross section depends critically on invariant mass of diffractive system (and available phase space for emission) MassPOMWIG (C.inel) KMR exclusive (hep-ph/0111078) ~20 GeV (dijets ET > 7 GeV) 33nb (CDF cuts) 1nb ~70 GeV (dijets ET > 25GeV) 8nb (CDF cuts) 230nb (~  < 0.1) 60nb 115 GeV (Higgs) 0.02fb0.2fb consistent with CDF data KMR cuts:  IP IP+IR CDF cuts: 0.035 <  < 0.095 0.01 <  < 0.03 IP IP+IR

11. Summary fb KMR and CFH agree, but CFH miss out LO piece, accounted for by larger gap survival factor BDPR very large – can’t be accounted for by lower IP intercept crucial (and possible) to observe exclusive dijet production in different mass ranges (~1 nb ET > 7 GeV) at Run II to check these conclusions.