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

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.

What do we calculate?

Khoze, Martin & Ryskin, hep-ph/0207313

“Inclusive” (Central-inelastic) process

p+p p + gap + H + X + gap + p

What do we calculate?

Results

CDF measured 44 20 nb

S2 = 0.1

S2 ~ 0.02 ~6fb

Enberg ~ 2 fb

Higgs cross sections

IP + IR, IP= 1.20, IR=0.57 (POMWIG defaults) ,

MH = 115 GeV

What effect does the intercept have?

H1 fit 2

S2 = 0.02

S2 = 0.1

(CDF data)

Theory:

S2 = 0.05

Khoze, Martin & Ryskin, hep-ph/0207313

fb fb

Are these diagrams as large a contribution as KMR calculate?

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)

Exclusive vs. C.inel

• Cross section depends critically on invariant mass of diffractive system (and available phase space for emission)

Mass POMWIG

(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) 60nb115 GeV(Higgs)

0.02fb 0.2fb

consistent with CDF data

KMR cuts:

IP

IP+IR

CDF cuts:

0.035 < < 0.095

0.01 < < 0.03

IP

IP+IR

Summary fb 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.