Transcript HSQCD08

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
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PLAN
1. 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.
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CMS & ATLAS were designed and optimised to look beyond the SM
The LHC is a discovery machine !
 High -pt signatures in the central region
But…
• Main physics ‘goes Forward’
The LHC is a very challenging machine!
•Difficult background conditions, pattern recognition, Pile Up...
• The precision measurements are limited by systematics
(luminosity goal of δL ≤5% , machine ~10%)
Lack of :
The LHC is not a precision machine (yet) !
•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 , …
ILC/CLIC chartered territory
p
p
RG
Is there a way out?
X
YES  Forward Proton Tagging
Rapidity Gaps  Hadron Free Zones
matching Δ
Mx ~ δM (Missing Mass)
RG
p
p
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Forward Proton Taggers as a gluonic Aladdin’s Lamp
(Old and New Physics menu)
•Higgs Hunting (the LHC ‘core business’)
•Photon-Photon, Photon - Hadron Physics.
•‘Threshold Scan’: ‘Light’ SUSY
…
•Various aspects of Diffractive Physics (soft & hard ).
•High intensity Gluon Factory (underrated gluons)
QCD test reactions, dijet P-luminosity monitor
(~20
mln quraks vs 417 ‘tagged’ g at LEP)
•Luminometry
•Searches for new heavy gluophilic states
and many other goodies…
FPT
Would provide a unique additional tool to complement the conventional
strategies at the LHC and ILC.
FPT  will open up an additional rich physics menu ILC@LHC
Higgs is only a part of the broad EW, BSM and diffractive program@LHC
wealth of QCD studies, glue-glue collider, photon-hadron, photon-photon interactions…
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(Khoze-Martin-Ryskin 1997-2008)
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(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
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KMR-based
arXiv:0712.0604 ,
PRD to appear soon
A killing blow to the wide range of theoretical models.
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2 (+10)  Excl. Events (CDF)
Current consensus on the LHC Higgs search prospects
•SM Higgs : detection is in principle guaranteed for any mass.
mH (SM) <160 GeV @95% CL
•In the MSSM h-boson most probably cannot escape detection, and in large
areas of parameter space other Higgses can be found.
•But there are still troublesome areas 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 (Higgs Identification):

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 .
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The main advantages of CED Higgs production
•
•
Prospects for high accuracy (~1%) mass measurements
(irrespectively of the decay mode).
H
Quantum number filter/analyser.
( 0++ dominance ;C,P-even)
•
H ->bb opens up (Hbb- coupl.)
(gg)CED
•
•
•

bb in LO ; NLO,NNLO, b- mass effects - controllable.
For some areas of the MSSM param. space CEDP may become a discovery channel !
H →WW*/WW - an added value ( less challenging experimentally + small bgds., better PU cond. )
New leverage –proton momentum correlations

LHC : ‘after
(probes of QCD dynamics , CP- violation effects…)
discovery stage’, Higgs ID……
How do we know what we’ve found?
mass, spin, couplings to fermions and Gauge Bosons, invisible modes…
 for all these purposes the CEDP will be particularly handy !
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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->WW mode at M>135 GeV. (B.Cox et al-06)

MSSM
enhanced trigger strategy & improved
timing detectors (FP420, TDR)
situation in the MSSM is very different
from the SM
SM-like
>
4 generations:enhanced Hbb rate (~ 5 times )
Conventionally due to overwhelming QCD
backgrounds, the direct measurement of Hbb
is hopeless
The backgrounds to the diffractive H bb mode are
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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
ggqq
(Mangano & Parke)
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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)
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New Tevatron data still pouring
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Simulation : A.Pilkington
Shuvaev et al-08
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A.G. Shuvaev et al. arXiv:0806.1447 [hep-ph]
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HKRSTW (arXiv: 0708.3052[hep-p])
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Other BSM Scenarios

‘ Invisible ‘ Higgs
several extensions of the SM:
H
B(KMR)-04
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 directly on 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 CEP  enhanced Hbb rate (~ 5 times ), while WBF is suppressed.
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(J.R. Forshaw, J.F. Gunion, L. Hodgkinson, A. Papaefstathiou, A.D. Pilkington, arXiv:0712.3510)
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haa
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
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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%
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CONCLUSION
God Loves Forward ProtonS
Forward Proton Tagging would significantly extend the physics reach of
the ATLAS and 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 BSM scenarios the FPT may be the Higgs discovery channel.
FPT offers a sensitive probe of the CP structure of the
Higgs sector.
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FP-420
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Backup
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Higgs boson
Nowhere to Run ! Nowhere to Hide !
REWARD
2.5 billion
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Are the early LHC runs,
without proton taggers,
able to check estimates
for pp  p+A+p ?
KMR: 0802.0177
gap
gap
Possible checks of:
(i) survival factor S2:
(ii) generalised gluon fg :
(iii) Sudakov factor T :
(iv) soft-hard factorisation
(enhanced absorptive corrn)
W+gaps,
Z+gaps
p Up
3 central jets
#(A+gap) evts
#(inclusive A) evts
with A = W, dijet, U…
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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.
(gg)CED  bb
• Unique access to a host of interesting
QCD processes
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 …
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SM Higgs
WW decay channel: require at least one W to decay
leptonically (trigger). Rate is large enough….
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Cox, de Roeck, Khoze, Pierzchala, Ryskin, Stirling, Nasteva, Tasevsky-04
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arXiv:0708.3052 [hep-ph]
Based on collaboration with S.Heinemeyer, M.Ryskin, W.J.Stirling, M.Tasevsky & G. Weiglein
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Exclusive SM Higgs production
WishList
b jets :
MH = 120 GeV s = 2 fb (uncertainty factor ~2.5)
MH = 140 GeV s = 0.7 fb
WW* :
MH = 120 GeV s = 0.4 fb
MH = 140 GeV s = 1 fb
H
MH = 140 GeV : 5-6 signal / O(3) background in 30 fb-1 (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)
•The WW 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- tags  the quantum numbers are 0++
H
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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)
suppressed
enhanced
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 the
discovery channel , and is certainly a powerful spin/parity filter
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KKMR-04
decoupling regime
mA ~ mH 150GeV,
tan >10;
h = SM
intense coupling:
mh ~ mA ~ mH
,WW.. coupl
suppressed
with CEDP:
•h,H may
be
clearly distinguishable
outside130+-5 GeV
range,
•h,H widths are quite
different
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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
CP even
CP odd active at
non-zero t
A is practically uPDF - independent
(Similar results in tri-mixing scenaio (J.Ellis et al) )
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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 )
B. Cox et al
H
Shuvaev et al-08
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