390 likes | 512 Views
Studying the BSM Higgs sector by forward proton tagging at the LHC. V.A. K hoze (IPPP, Durham & PNPI, St. Petersburg ). (Based on works with S .H einemeyer, A. M artin, M. R yskin, W.J. S tirling, M. T asevsky and G. W eiglein).
E N D
Studying the BSM Higgs sector by forward proton tagging at the LHC V.A. Khoze(IPPP, Durham & PNPI, St. Petersburg ) (Based on works with S.Heinemeyer, A.Martin, M.Ryskin, W.J.Stirling, M.Tasevsky and G.Weiglein) main aim:to demonstrate that the Central Exclusive Diffractive Production can provide unique advantages for probing the BSM Higgs sector
PLAN • Introduction(gluonic Aladdin’s lamp) • 2. Central Exclusive Diffractive Production (only a taste). • 3. Prospects for CED MSSM Higgs-boson production. • 4. Other BSM scenarios. • 5. Conclusion.
The LHC is a discovery machine ! • CMS & ATLASwere designed and optimised to look beyond the SM • High -pt signatures in the central region • But… • Main physics ‘goes Forward’ • Difficult background conditions, pattern recognition, Pile Up... • The precision measurements are limited by systematics • (luminositygoal ofδL ≤5% , machine ~10%) • Lack of : • Threshold scanning , resolution of nearly degenerate states • (e.g. MSSM Higgs sector) • Quantum number analysing • Handle on CP-violating effects in the Higgs sector • Photon – photon reactions , … The LHC is a very challenging machine! The LHC is not a precision machine (yet) ! ILC/CLIC chartered territory p p RG Is there a way out? X YES Forward Proton Tagging Rapidity Gaps Hadron Free Zones matchingΔ Mx ~δM (Missing Mass) RG p p
Forward Proton Taggersas a gluonicAladdin’s Lamp • (Old and NewPhysics menu) • Higgs Hunting(the LHC ‘core business’) • Photon-Photon, Photon - HadronPhysics. • ‘Threshold Scan’:‘Light’ SUSY … • Various aspects of DiffractivePhysics (soft & hard ). • •High intensityGluon Factory(underrated gluons) (~20 mln quraks vs 417 ‘tagged’ g at LEP) • QCD test reactions, dijet P-luminosity monitor • Luminometry • Searches for new heavy gluophilic states • and many other goodies… • FPT • Would provide a unique additional tool to complement the conventionalstrategies at theLHCandILC. Higgs is only a part of the broad EW, BSM and diffractiveprogram@LHC wealth of QCD studies, glue-glue collider, photon-hadron, photon-photon interactions… FPT will open upan additional richphysics menu ILC@LHC
(Khoze-Martin-Ryskin1997-2008) -4 (CDPE) ~ 10 (incl) (Fulvio’s talk) New CDF results not so long ago: between Scylla and Charibdis: orders of magnitude differences in the theoretical predictions are now a history
KMR-based arXiv:0712.0604 , PRD to appear soon A killing blow to the wide range of theoretical models. 2 (+10) Excl. Events (CDF)
Current consensus on the LHC Higgs search prospects • SM Higgs : detection is in principle guaranteed for any mass. • In the MSSMh-boson most probably cannot escape detection, and in large areas of parameter space other Higgses can be found. • But there are still troublesomeareas of the parameter space: • intense coupling regime of MSSM, MSSM with CP-violation… • More surprises may arise in other SUSY • non-minimal extensions: NMSSM…… • ‘Just’ a discovery will not be sufficient! • After discovery stage(HiggsIdentification): • The ambitious program of precise measurements of the Higgs mass, width, couplings, • and, especially of the quantum numbers and CP properties would require • an interplay with a ILC . mH (SM) <160 GeV @95% CL
The main advantages of CED Higgs production • Prospects for high accuracy (~1%) mass measurements • (irrespectively of the decay mode). • Quantum number filter/analyser. • ( 0++dominance ;C,P-even) • H ->bb opens up (Hbb- coupl.) • (gg)CED bb inLO ; NLO,NNLO, b- masseffects - controllable. • For some areas of the MSSM param. spaceCEDP may become adiscovery channel! • H→WW*/WW - an added value (less challenging experimentally + small bgds., better PUcond. ) • New leverage –proton momentum correlations (probes of QCD dynamics , CP- violation effects…) H How do we know what we’ve found? LHC : ‘after discovery stage’,Higgs ID…… mass, spin, couplings to fermions and Gauge Bosons, invisible modes… for all these purposes the CEDP will be particularly handy !
without ‘clever hardware’: for H(SM)bb at 60fb-1 only a handful of events due to severe exp. cuts and low efficiencies, though S/B~1 . But H->WWmode at M>135 GeV. (B.Cox et al-06) enhanced trigger strategy & improved timing detectors (FP420, TDR) MSSM situation in the MSSM is very different from the SM SM-like > 4 generations:enhancedHbbrate (~ 5 times ) Conventionally due to overwhelming QCD backgrounds, the direct measurement of Hbb is hopeless The backgrounds to the diffractive H bb mode are manageable!
for Higgs searches in the forward proton mode the QCD bb backgrounds are suppressed by Jz=0 selection rule and by colour, spin and mass resolution (M/M) –factors. There must be a god ! KMR-2000 (Mangano & Parke) ggqq
Four integrated luminosity scenarios HKRSTW, arXiv:0708.3052 [hep-ph] (bb, WW,- modes studied) • L = 60fb-1: 30 (ATLAS) + 30 (CMS): 3 yrs with L=1033cm-2s-1 2.L = 60fb-1, effx2: as 1, but assuming doubled exper.(theor.) eff. 3. L = 600fb-1: 300 (ATLAS) + 300 (CMS) : 3 yrs with L=1034cm-2s-1 4. L = 600fb-1,effx2: as 3, but assuming doubled exper.(theor.) eff. upmost ! We have to be open-minded about the theoretical uncertainties. Should be constrained by the early LHC measurements (KMR-08)
Simulation : A.Pilkington Shuvaev et al-08
Other BSM Scenarios ‘ Invisible ‘ HiggsB(KMR)-04 H • several extensions of the SM: fourth generation, • some SUSY scenarios, • large extra dimensions,… • (one of the ‘LHC headaches’ ) • the potential advantages of the CEDP – a sharp peak in the MM spectrum, mass determination, quantum numbers • strong requirements : • triggering directlyon L1 on the proton taggers • or rapidity gap triggers (forward calorimeters,.., ZDC) Implications of fourth generation (current status: e.g.G.Kribs et.al,arXiv:0706.3718) For CEPenhanced Hbb rate (~ 5 times ), while WBF is suppressed.
(J.R. Forshaw, J.F. Gunion, L. Hodgkinson, A. Papaefstathiou, A.D. Pilkington, arXiv:0712.3510)
haa Low mass higgs in NMSSM: If ma < mB difficult (impossible) at standard LHC J. Gunion: FP420 may be the only way to see it at the LHC 150 fb-1
Long Lived gluinos at the LHC P. Bussey et al hep-ph/0607264 Gluino mass resolution with 300 fb-1 using forward detectors and muon system The event numbers includes acceptance in the FP420 detectors and central detector, trigger… R-hadrons look like slow muons good for triggering Measure the gluino mass with a precision (much) better than 1%
CONCLUSION God Loves Forward ProtonS Forward Proton Taggingwouldsignificantlyextend the physics reachof the ATLASand CMS detectors by giving access to a wide range of exciting new physics channels. FPT has the potential to make measurements which are unique at LHC and challenging even at a ILC. For certain BSMscenarios theFPT may be the Higgs discovery channel. FPT offers a sensitive probe of the CP structure of the Higgs sector.
Higgs boson Nowhere to Run ! Nowhere to Hide ! 2.5 billion REWARD
KMR: 0802.0177 Are the early LHC runs, without proton taggers, able to check estimates for pp p+A+p ? gap gap Possible checks of: (i) survival factor S2:W+gaps, Z+gaps (ii) generalised gluon fg : gp Up Divide et Impera (iii) Sudakov factor T : 3 central jets (iv) soft-hard factorisation #(A+gap) evts (enhanced absorptive corrn)#(inclusive A) evts with A = W, dijet, U…
Exclusive Central Production Very promising addition to the ‘party line’ Higgs studies at the LHC and even at the ILC/CLIC (KMR, J.Ellis et al, Manchester group ) • Selection rules mean that central system is 0++ pinning down the quantum numbers • CP violation in the Higgs sector shows up directly as azimuthal asymmetries • Tagging the protons means excellent mass resolution (~ GeV) irrespective of the decay products of the central system. LO QCD backgrounds suppressed • Proton tagging may be the discovery channel in certain regions of the MSSM. • Unique access to a host of interesting QCD processes (gg)CED bb Very schematically: exclusive central production is a glue – glue collider where you know the beam energy of the gluons - source of pure gluon jets - and central production of any 0++ state which couples strongly to glue is a possibility …
SM Higgs WW decay channel: require at least one W to decayleptonically (trigger). Rate is large enough…. Cox, de Roeck, Khoze, Pierzchala, Ryskin, Stirling, Nasteva, Tasevsky-04
arXiv:0708.3052 [hep-ph] Based on collaboration with S.Heinemeyer, M.Ryskin, W.J.Stirling, M.Tasevsky & G. Weiglein
Exclusive SM Higgs production b jets : MH = 120 GeV s = 2 fb (uncertainty factor ~2.5) MH = 140 GeV s = 0.7 fb WishList WW* : MH = 120 GeV s = 0.4 fb MH = 140 GeV s = 1 fb MH = 140 GeV :5-6 signal / O(3) background in 30 fb-1 H (with detector cuts) • The b jet channel is possible, with a good understanding of detectors and clever level 1 trigger ( μ-trigger from the central detector at L1 or/and RP(220) +jet condition) • TheWW channel is very promising : no trigger problems, better mass resolution at higher masses (even in leptonic / semi-leptonic channel), weaker dependence on jet finding algorithms, better PU situation • The mode looks advantageous • If we see SM-like Higgs + p- tagsthe quantum numbers are0++ H
suppressed enhanced The MSSM can be very proton tagging friendly The intense coupling regime is where the masses of the 3 neutral Higgs bosons are close to each other and tan is large (E.Boos et al, 02-03) 0++ selection rule suppresses A production: CEDP ‘filters out’ pseudoscalar production, leaving pure H sample for study Well known difficult region for conventional channels, tagged proton channel may well be thediscovery channel,and is certainly a powerful spin/parity filter
decoupling regime mA ~ mH150GeV, tan >10; h = SM intense coupling: mh ~ mA ~ mH ,WW.. coupl suppressed KKMR-04 • with CEDP: • h,Hmay be • clearlydistinguishable • outside130+-5 GeV range, • h,Hwidths are quite different
Probing CP violation in the Higgs Sector Azimuthal asymmetry in tagged protons provides direct evidence for CP violation in Higgs sector ‘CPX’ scenario ( in fb) KMR-04 A is practically uPDF - independent CP odd active at non-zero t CP even (Similar results in tri-mixing scenaio (J.Ellis et al) )
B. Cox et al Very promising addition to the ‘party line’ Higgs studies at the LHC and even at the ILC/CLIC (KMR, J.Ellis et al, Manchester Group ) H Shuvaev et al-08