Diffractive Higgs production at the LHC p Prod

Diffractive Higgs production at the LHC p Prod. of Higgs in diffve hadron-hadron collisions Otto Nachtmann et al. Phys, Lett. (1990) H p Alan Martin (Durham) 31 st John Hopkins Workshop Heidelberg, August 2007

Exclusive Higgs production at the LHC Khoze, Martin, Ryskin O(1 Ge. V) ? far from IP The price for rapidity gaps ?

calculated from multi-Pomeron multi-channel eikonal analysis of soft pp data S 2 = 0. 02 at LHC S 2 = 0. 05 at Tevatron no emission when (l ~ 1/kt) > (d ~ 1/Qt) i. e. only emission with kt > Qt

Description of ‘soft’ high energy pp interactions DL: aeff = 1. 08 + 0. 25 t ---but nothing about inelastic intn Inclusion of multi-P effects essential: new analysis N* + + KMR 2007 + …. abare ~ 1. 25 + 0 t full multi-Pomeron 2 -ch eikonal where = + stotal(LHC) ~ 95 mb S 2 Higgs(LHC) ~ 0. 02 + + ….

Prediction of s(pp p + H + p) H contain Sudakov factor Tg which exponentially suppresses infrared Qt region p. QCD S 2 is the prob. that the rapidity gaps survive population by secondary hadrons soft physics S 2=0. 02 (LHC) S 2=0. 05 (Tevatron) s(pp p + H + p) ~ 3 fb at LHC for SM 120 Ge. V Higgs ~0. 2 fb at Tevatron

s(pp p+H+p) ~ 3 fb if L = 60 fb-1, at LHC for 120 Ge. V Higgs then 180 events efficiency of p taggers 54 36 18 9 BR(H bb) b, b tag efficiency polar angle cut mass window 6 events

Background to pp p + (H bb) + p signal assuming DMmiss ~ 3 s. M ~ 5 Ge. V LO B/S (=0 if mb=0, forward protons) gg mimics gg bb (P(g/b)=1. 3%) after polar angle cut Irreducibe bb HO 0. 3 0. 5 (gg)col. sing bb+ng Soft emissions still suppressed by Jz=0 Hard emissions if g not seen: extra gluon along beam Mmiss > Mbb extra g from initial g along b or b Pomeron-Pomeron inelastic for M=120 Ge. V ~0 ~0 0. 2 0. 06 total B/S~1 S~1/M 3, B~DM/M 6 : triggering, tagging, DM better with rising M

hard P signal backgd 150 20 70 5 soft P ds/dy|y=0 units 10 -3 fb k. T<5 Ge. V DMdijet/Mbb=20% DMmissing=4 Ge. V 0. 14 9

conventional signal for SM 110 -130 Ge. V Higgs

eikonal enhanced S 2 =0. 02 BBKM. (first) corrn could be large and -ve,

BBKM find first corrn could be large and –ve. BUT…need to sum complete set of diagrams. terms alternate in sign Amp 70% sum Analogous new “soft” analysis finds that even 1 st term QT~2 Ge. V at low QT, amp. is not completely suppressed corrn affects only small QT (large size dipoles) ln QT 2

New global fit to “soft” data The full set of enhanced diag. are included in stot, s. SD … in global soft fit The fit to “soft” data including enhanced rescatt. --redistributes abs. effects between eik. and enh. --find total S 2 same Analogously predn for stot(LHC) has v. weak model dep. since model fits existing soft data and there is log s energy behaviour s. SD, sensitive to enh. effects, ~flat from 100 Ge. V, so expect no extra suppression of diffraction at LHC

g g g Leading neutron prod. at HERA KKMR ‘ 06 gap due to p exchange ~ exclusive Higgs eikonal g seen “enhanced” g g g not seen yi > 2 – 3 correction prop. to rap. interval prop. to g energy (negative) Prob. to observe leading neutron must decrease with g energy But expt. flat small enhanced correction

Level 1 trigger 420 220 veto 420 veto-trigger spoiled by pile-up 420 -trigger spoiled by c ------- buffer ? At present, plan to use 2 high ET jets/m + 220 (+ 420)

LHC every bunch crossing !

~0. 01 N for 420 m ~0. 03 N for 220 m

SUSY Higgs: h, H, A, (H+, H--) There are parameter regions where the pp p + (h, H) + p signals are greatly enhanced in comparison to the SM Selection rule favours 0++ diffractive production

decoupling regime: m. A ~ m. H > 150 h ~ SM bb. H ~ tanb VVH ~ 0 H, A tt (bb) intense coup: mh ~ m. A ~ m. H gg, WW. . coup. suppressed

exclusive signal 5 s signal at LHC 100 fb-1

Adapted from a preliminary plot of Tasevsky et al. (HKRSTW)

Possible checks of exclusive rates at the Tevatron “standard candles” at Tevatron to test excl. prod. mechanism pp p + c + p high rate, but only an ord. -of-mag. estimate pp p + jj + p rate OK, but jet algorithm, hadronization etc “standard candles” pp p + gg + p low rate, but cleaner signal

pp p + gg + p KMR+Stirling

Measurements with Mgg=10 -20 Ge. V could confirm s. H(excl) prediction at LHC to about 20% or less

CDF Blessed this morning! CDF, Albrow et al. 16 events observed one appears due to p 0 gg 3 events observed ~0. 09 pb ~0. 04 pb QED: LPAIR Monte Carlo It means exclusive H must happen (if H exists) and probably ~ 10 fb within factor ~ 2. 5. higher in MSSM s(gg) = 10 fb for ETg>14 Ge. V at LHC

16 events were like this: 3 events were like this: Albrow one appears due to p 0 gg

pp p + jj + p Exptally more problematic due to hadronization, jet algorithms, detector resolution effects, QCD brem… Exclusive events have Rjj = Mjj/MX =1, but above effects smear out the expected peak at Rjj = 1 (Ex. Hu. ME MC) sexcl~Rjj>0. 8 sexcl(M>Mjj)

Conclusion The pp p+H+p cross section prediction is robust----factor 2 S/B~1 for SM h -----can be more for SUSY h, H. Checks are starting to come from Tevatron data (gg, dijet…) There is a strong case for installing proton taggers at the LHC, far from the IP ---- it is crucial to get the missing mass DM of the Higgs as small as possible. Need more exptal and theoretical work on L 1 trigger The diffractive Higgs signals beautifully complement the conventional signals. Indeed there are SUSY Higgs regions where the diffractive signals are advantageous ---determine DMH, Yukawa H bb coupling, 0++ ---searching for CP-violation in the Higgs sector