Central Exclusive Production at the Tevatron (CDF)

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Central Exclusive Production at the Tevatron (CDF)
Mike Albrow (Fermilab) for the CDF Collaboration
pp ? p X p where X is a simple system
completely measured
VeryFewParticle
Introduction ISR p p- etc. Tevatron ee-,
??, µµ-, J/?, ?(2S), ?_c, ? . Z? LHC Z, H,
WW-,
JJ
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ISR Tevatron -- LHC
p
p
p
p
G?
H?
p
p
p
p

• Central Exclusive Production
• LHC Study of Higgs through p H p, WW and ZZ
  
• FP420 RD project proposing extensions to
  ATLAS CMS.

Our measurements are the first 2-photon in
hadron-hadron, and test both the production
mechanisms and calibration techniques.
same diagram
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Central Exclusive Production in Different Machines
In collisions (through LEP energies ? I
L C) ? hadrons,
and at high energy WW ? WW, WW ? Z,H WZ ? W
In ep collisions (HERA) gamma-IP ? vector
mesons ( too but
buried?) In (ISR ? Tevatron
and LHC) IP IP ? hadrons (can be single
hadron), Higgs, -IP ? vector mesons (..
,Y, Z(allowed but tiny)) ? ll- (
too but buried?) In AA (RHIC, LHC) mainly
(E-fields) -IP and IPIP
New in CDF
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Central Exclusive Production is very clean, no
backgrounds
p
-7.4
7.4
y lt 1
Rapidity y
p
With rapidity gaps gt 6 on both sides,
t-channel exchanges are very limited Charge Q
0, No color, and spin J gt 1.0 Allowed
exchanges only photons, IP pomeron
gg Odderon ggg not yet observed, Z (but p
would always break up!)
t
only from IP, OIP(?)
only from , continuum. only from
IPIP.
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Central Exclusive Production of Higgs
Higgs has vacuum quantum numbers, vacuum has
Higgs field. So pp ? pHp is possible. Allowed
states Process is gg ? H through t-loop as
usual with another g-exchange to cancel color and
even leave ps in ground state. If measure ps
J gt 2 strongly suppressed at small p angle (t)
t
H
4-vectors
!
MGARostovtsev hep-ph/0009336
Aim be limited by incoming beam momentum spread
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Central Exclusive Production at ISR
63 GeV (AFS)
Axial Field Spectrometer (R807) Added very
forward drift chambers
D.P.E. Search for Glueballs
p
p
data
ALSO
3500 events/25 MeV
G(1710)??
Structures not well understood beyond f(980) Not
studied at higher
DPE ? would be great for G-spectroscopy.
Waiting to be done at Tevatron! Student?
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CDF Detector at Fermilab Tevatron
Muon Chambers Calorimeters
MiniPlugs
980 GeV pbar
980 GeV p
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Installed very forward Beam Shower Counters (BSC)
for rapidity gaps and scintillating fiber
trackers in Roman pots for pbar detection
Not at all to scale! Roman pot detectors 20mm x
20mm 55 m downstream. Beam Shower Counters BSC
tight around pipe. Full coverage 7.4 lt lt
7.4
by beam shower counters
In this talk I do not use Roman pots do not
have acceptance for low mass
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Exclusive Electron-Positron Production in Hadron
Collisions (CDF)
Phys.Rev.Lett 98,112001(2007)

16 events
QED process collisions in pp
Monte Carlos LPAIR, GRAPE, STARLIGHT
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Exclusive H Theory Calibration Exclusive
2-Photon
MGA et al. (2001) hep-ex/0511057
Khoze, Martin and Ryskin, hep-ph/0111078,
Eur.Phys.J. C23 311 (2002) KMRStirling
hep-ph/0409037 QCD diagram identical to pHp
Tevatron
36 fb
Claim factor 3 uncertainty Correlated to pHp
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Exclusive Production in Hadron-Hadron
Collisions
Phys.Rev.Lett. 99,242002 (2007)
3 candidates observed
s
Prediction V.A.Khoze et al. Eur. Phys. J C38, 475
(2005) (our cuts) (36 72 24) fb 0.8
1.6 0.5 events. Cannot yet claim discovery as
b/g study a posteriori, 2 events corresponds to
90 fb, agreeing with Khoze et al.
It means exclusive H must happen (if H exists)
and probably 5 fb within factor 3.
is higher in MSSM
ExHuME Monte Carlo James Monk Andy Pilkington
(MCR)
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New Results, hot off the press
Region rich in physics. First observations in
(elastic) hadron-hadron
1)
2)
3)
1 2 ) Forward proton momenta precisely known
calibrate momentum scale of forward
spectrometers for p p ? p H p at LHC. 3)
Calibrate theory (x-sn) of p H p
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There are 4, maybe 5, physics processes in this
data!
IP pomeron

• 2-photon (QED) production of the continuum (no
  resonances)
• We published this in 2007 for ee- ee with
  M gt 10 GeV (16 events as in QED)
• Photon IP ? photoproduction, as in
  ep at HERA
• Photon IP ? photoproduction, as in
  ep at HERA
• IP IP ?

or
1)
2,3)
4)
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Data Feb 2002 March 2007 Luminosity (Good
Runs) 1.48/fb (/- 6) Trigger muon track
BSC1 gaps ? 2 muons Number of events on tape
1.6 million
)
Reject cosmic ray events (ToF, colinearity)
100 efficient Exclusivity Require all detectors
lt noise cuts except in mumu direction
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Exclusivity cuts
Want to be sure no other particles were
produced. Take 0-bias bunch crossing data. Put
in two classes non-interaction (dominated), no
tracks, no CLC hits, no muon stubs
interaction (dominated), all
others For each sub-detector 5 calorimeter
regions, 3 BSC counter hodoscopes Find largest
signal and plot it as Log_10 max ADC counts
We did this for each of (11) periods of data,
finding cut efficient at selecting nothing i.e.
noise thresholds. Red mini-peak is not
ineffiency, mainly mini-gaps with no pile-up.
500 ADC counts
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36 bunch x bunch crossings Have different
luminosities Distribution over a
period Exclusive efficiency Exclusive
efficiency x L(bunch) Integral L_1(effective)
no PU
Eff(excl) 0.093 , 1.48/fb ? (139 /- 8)
/pb (6)
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Single muon acceptance gt 90 for pT gt 1.5
GeV. Lower pT range out in calorimeters
Very well fit by empirical function F 0.1 at M
3.05 F 0.6 asymptotically
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(No Transcript)
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402 events
Fit 2 Gaussians QED continuum. Masses 3.09,
3.68 GeV PDG Widths 15.8,16.7
MeVresolution. QED generator x acceptance 3
amplitudes floating
Paper in preparation
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x QED spectrum
Only normalization A floating
STARLIGHT LPAIR MCs Good description v.low pT
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photoproduction (or possible odderon
exchange) Kinematics well described by STARLIGHT
MC Much broader pT,dphi than
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photoproduction (or possible odderon
exchange) Kinematics well described by STARLIGHT
MC Much broader pT,dphi than
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Dissociation background Take (90 /- 10) for
eff (BSC)
(10 /- 3)
Non-exclusive correction QED 0.91 /-
0.05 J/psi, psi 0.97 /- 0.03
Indication of small non-exclusive b/g as not
described by MC
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Exclusive (lt80 MeV)
Best fit is with 1/3 but with very large
uncertainty
Interpretations (1) Large component (not
supported by Method 2) (2) Decay simulations not
precise (3) 1.5 sigma fluctuation (4) An odderon
component (also ? larger )
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Events with EM shower
Good fits to mumu kinematics with only chi_cs,
if EM shower
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EmEt spectrum with J/psi mass cut
Empirical functional form
Fit shown (ET in MeV) A 0.00025 B 2.5 C
0.0125 (per MeV)
Fraction under 80 MeV small 2.8 below 80 MeV (1
of J/psi) From varying A,B,C (1 /- 1) ?
chi_c 68 /- 8
Combine (1) and (2) f (1.9 2.8 -1.9) Total
number of chi_c 68.2 (65.2 are above 80 MeV cut)
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Run,Evt 220182.13272933 M3.101, pT1.54,
dphi2.18
CENTRAL DRIFT CHAMBER
CALORIMETERS LEGO PLOT
BSC empty
CLC W empty
CLC E empty
Note CLC and BSC all empty although we did not
require that.
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Summary of Results
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Summary of Results
Assumed
Suppressed by J_z0 rule
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Search for Odderon exchange
Odderon O, C -1 partner to IP at least 3
gluons
In QCD but not yet observed.
Possibly O IP ?
Signature Excess of exclusive
and Upsilons Y over rate expected from
photoproduction (tuned to HERA data). t(p)-distrib
ution would be flatter and hence VM should have
larger ltpTgt and Kinematic behavior different, but
not well known. not known
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Some predictions for J/psi photoproduction
e.g. Schafer and Szczurek arXiv0705.2887
hep-ph
Machado,Goncalves 3.0 nb Khoze, Martin, Ryskin
Motyka and Watt 3.4 nb Schafer Szczurek
2.8 nb Nystrand 2.2 nb Our result 3.96 -
0.64 nb
Machado is considered too high by KMR
Take 3.0 - 0.8
We are consistent, so we can put a limit on
odderon exchange. If theory gets more precise,
our limit can change
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Odderon Limits and ratios
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Invariant Mass Distribution - Upsilon Region
Trigger µµ- ?lt0.6 , pT(µ) gt 4 GeV/c
CDF Run II Preliminary
Inclusive
Photo-production of Y, Y (first observation in
hadron-hadron)
Y(1S)
Invariant Mass (nassoc_tracks 0) pT(µµ) lt
6GeV/c
CDF Run II Preliminary
Y(2S)
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Exclusive Upsilon(1S) candidate
Run/Event 204413/8549136
M 9.4 GeV
R-z, Muon hits
Lego, threshold ET gt 10 MeV
Plugs, Miniplugs, CLC, BSC empty
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Search for Exclusive Z, and observe high mass
lepton pairs. Spectrum extends to M(ll) gt 100 GeV!
We have observed a candidate exclusive
event with M 64 GeV, which appears to be
exclusive.
Run 166529 Event 10107956
Forward counters both sides CLC and BSC were
empty. Roman pot had pbar track
This is exactly the type of event for calibrating
p(FP420)
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FP420 Forward Protons 420m downstream of CMS
ATLAS
CMS Inner Vacuum Tank insertion
CMS


420 220m
220 420m
ATLAS
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Summary
We have observed the following exclusive states X
in p X p at the Tevatron with CDF
These are all first observations for
hadron-hadron elastic. (unless you call A,Z a
hadron)
processes agree with QED predictions
Photoproduction of V agree with expectations
HERA. Hence limit on odderon exchange, near
theory.
IPIP ?
within theoretical uncertainties, and
demonstrates that exclusive H should happen, if H.
Furthermore, exclusive di-leptons provide a
calibration of forward p spectrometers,
momentum scale and resolution
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BACK UPS
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Cosmic rays would be at 0
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What is exclusive H cross section?
Calculation involves gg ? H (perturbative,
standard, NLO) Unintegrated gluon
densities Prob.(no other parton interaction)
(Gap survival) Proton form factor Prob.(no
gluon radiation ? no hadrons) Sudakov Suppression
H
3 fb (M(H)125 GeV) factor 3
uncertainty 30 fb-1 ? 100 Ae events (Ae
acceptance, efficiency) But other estimates
differ by large amounts! Need to calibrate
theory!
Exclusive
Durham Gp Khoze, Martin, Ryskin,
Stirling hep-ph/0505240