1Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
Central Exclusive Production at the Tevatron (CDF)Mike Albrow (Fermilab) for the CDF Collaboration
Introduction
ISR : π+ π- etc.
Tevatron: e+e-, γγ, μ+μ-, J/ψ, ψ(2S), χ_c, Υ …. Z?
LHC: Z, H, W+W-, …
pp p X p where X is a simple system completely measured
JJ
VeryFewParticle
2Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
ISR – Tevatron -- LHC
1) Central Exclusive Production:
2) LHC: Study of Higgs through p + H + p, WW and ZZ + + + FP420: R&D project; proposing extensions to ATLAS & CMS.
pp
pp
p
p
p
p
W
-WG? H?
Our measurements are the first 2-photon in hadron-hadron, and test both the production mechanisms and calibration techniques. ~ same diagramH,χ c
bcJee ,,,',/,, ,...~~
,, llWWH ppKK ,,
3Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
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)) l+l- ( too but buried?)
In AA (RHIC, LHC) mainly (E-fields) -IP and IP+IP
Central Exclusive Production in Different Machines
New in CDF
eeqqll ,
,/,, J
γγγ
ll
ll
γγ
)p(ppp
γ
4Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
Central Exclusive Production is very clean, ~ no backgrounds
Rapidity y
~ 7.4~ -7.4
pp ,,)'(, ,bc
|y| < 1
With rapidity gaps > 6 on both sides, t-channelexchanges are very limited:Charge Q = 0, No color, and spin J >= 1.0
Allowed exchanges: only photons, IP = pomeron {~gg}Odderon {~ggg} not yet observed,Z (but p would always break up!)
y p
p
t
only from , continuum. only from IPIP. bc,
)'( only from IP, OIP(?)
yy
5Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
Central Exclusive Production of Higgs
Higgs has vacuum quantum numbers, vacuum has Higgs field.So pp p+H+p is possible.Allowed states:
Process is gg H through t-loop as usualwith another g-exchange to cancel colorand even leave p’s in ground state.If measure p’s:
H
2CEN 1 2 3 4M ( )p p p p
+ - ±Even for H W W l νJJ !
Aim: be limited by incoming beam momentum spreadp -4σ
10 0.7 GeVp
MGA+Rostovtsev: hep-ph/0009336
PC ++I J =0 even
J >= 2 strongly suppressed at small p angle (t)
t
4-vectors
( ) 2 GeV per eventHM
0c
0b
u-loop : γγ c-loop : χ
b-loop : χ t-loop: H
6Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
G(1710)??
0 (980)f
No ρ
Structures not well understood beyond f(980)Not studied at higher
Central Exclusive Production at ISR = 63 GeV (AFS)
3500 events/25 MeV )( M
DPE would be greatfor G-spectroscopy. Waitingto be done at Tevatron! Student?
ppandKKAlso
s
Axial Field Spectrometer (R807)Added very forward drift chambers
D.P.E. & Search for “Glueballs”
{ } as distinct from { }gg qq
data
pp
ALSO )600(0f
s
7Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
CDF Detector at Fermilab Tevatron
MiniPlugs
980 GeV p980 GeV pbar
Muon ChambersCalorimeters
8Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
Installed very forward Beam Shower Counters (BSC) for rapidity gapsand scintillating fiber trackers in Roman pots for pbar detection
Not at all to scale!
Roman pot detectors 20mm x 20mm55 m downstream.Beam Shower Counters BSC tight around pipe.Full coverage –7.4 < < +7.4
vetoedetc,; pnpby beam shower counters
In this talk I do not useRoman pots; do not haveacceptance for low mass
9Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
16 events
0 0: 180 2
( )10 38 GeV
small ( resolution)T
e e
M e e
p
QED process : collisions in ppγγ
Monte Carlos : LPAIR, GRAPE, STARLIGHT
Exclusive Electron-Positron Production in Hadron Collisions (CDF)
Phys.Rev.Lett 98,112001(2007)
0.5. 0.3
-9
Estimated background = 1.9 0.3
(mostly p-dissociation)
1.6 (stat) 0.3 (syst) pb
p-value = 1.3 10 ( 5 )
MEAS
QED (1.711 0.008) pb
TE ( ) 5 GeV; | ( ) | 2.0e e
10Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
Khoze, Martin and Ryskin, hep-ph/0111078, Eur.Phys.J. C23: 311 (2002)KMR+Stirling hep-ph/0409037
QCD diagram identical to pHp
36 fb
-1T~ 40 events per fb with p (γ) > 5 GeV/c & |η| < 1.0
& much smallerqq
Exclusive H Theory Calibration: Exclusive 2-PhotonMGA et al. (2001) hep-ex/0511057
21 2
M( ) ~ 10 20 GeV
, similar, lower
top u,c (mainly)
x x Q
Tevatron
Claim factor ~ 3 uncertainty ; Correlated to p+H+p
11Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
12Note : 2 10 !MEAS INEL
3 candidates observed:
It means exclusive H must happen(if H exists) and probably ~ 5 fbwithin factor ~ 3. is higher in MSSM
Phys.Rev.Lett. 99,242002 (2007)
Exclusive Production in Hadron-Hadron Collisions
TE ( ) > 5 GeV; | ( ) | 1.0
0 0
Actually 2 events are good candidate
and 1is a good candidate.
(Remember at ISR)
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 correspondsto ~ 90 fb, agreeing with Khoze et al.
s
ExHuME Monte CarloJames Monk &Andy Pilkington (MCR)
gg
12Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
New Results, hot off the press:
pppp 2
μμ2 GeV/c 4MGeV/c3
Region rich in physics. First observations in (elastic) hadron-hadron:
cχIPIP
ψ(2S) & J/ψIPγ
μμγγ
1 & 2 ) Forward proton momenta precisely known: calibrate momentum scale of forward spectrometersfor p + p p + H + p at LHC.3) Calibrate theory (x-sn) of p + H + p
1)
2)
3)
13Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
There are 4, maybe 5, physics processes in this data!
1) 2-photon (QED) production of the continuum (no resonances) We published this in 2007 for e+e- [ee] with M > 10 GeV (16 events as in QED)
2) Photon + IP … photoproduction, as in ep at HERA3) Photon + IP … photoproduction, as in ep at HERA4) IP + IP
/J)2(' S /Jc
IP = pomeron
1)
4)
2,3) )2(' Sor
14Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
Data: Feb 2002 – March 2007Luminosity (Good Runs) = 1.48/fb (+/- 6%)Trigger = muon + track +BSC1 gaps 2 muonsNumber of events on tape: ~ 1.6 million
2-T GeV/c4.0)μM(μ3.0GeV/c,1.4(μμp,0.6|η(μ)| )
Reject cosmic ray events (ToF, colinearity) … 100% efficientExclusivity: Require all detectors < noise cuts except in mumu direction
15Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
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 othersFor each sub-detector: 5 calorimeter regions, 3 BSC counter hodoscopesFind largest signal and plot it as [Log_10 max ADC counts]
We did this for each of (11)periods of data, finding cutefficient at selecting “nothing”i.e. noise thresholds.
Red mini-peak is not ineffiency,mainly mini-gaps with no pile-up.
500 ADC counts
16Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
Eff(excl) = 0.093 , 1.48/fb (139 +/- 8) /pb (6%)
36 bunch x bunch crossingsHave different luminositiesDistribution over a “period”Exclusive efficiencyExclusive efficiency x L(bunch)Integral = L_1(effective) – no PU
17Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
Very well fit by empirical function:F = 0.1 at M = 3.05F = 0.6 asymptotically
Single muon acceptance > 90% for pT > 1.5 GeV.Lower pT range out in calorimeters region. mass through rises )μA(μ
18Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
19Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
pppp
402 events
Fit: 2 Gaussians + QED continuum.Masses 3.09, 3.68 GeV == PDGWidths 15.8,16.7 MeV=resolution.QED = generator x acceptance3 amplitudes floating
Paper in preparation
20Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
/J )2( S
x QED spectrum~ M0.852
QED A.eF Only normalization A floating
STARLIGHT & LPAIR MCsGood description: v.low pT
μμγ γ:continuum QED
pb 2.18:QED LPAIR & STARLIGHT
pb 0.52.6
)GeV/c4MGeV/c30.6,|η|σ(
:)μμσ(γγA22
21Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
J/ψ photoproduction(or possible odderon exchange)
Kinematics well described bySTARLIGHT MC
Much broader pT,dphi than
μμγ γ:continuum QED
22Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
photoproduction(or possible odderon exchange)
Kinematics well described bySTARLIGHT MC
Much broader pT,dphi than
(2S)
μμγ γ:continuum QED
23Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
Dissociation background:Take (90 +/- 10%) for eff (BSC)
...,,* etcnppp (10 +/- 3)%
Non-exclusive correction:QED: 0.91 +/- 0.05J/psi, psi’ 0.97 +/- 0.03
Indication of small non-exclusive b/g as not described by MC
24Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
)/(pand)(:J/ψonfitsKinematic T J Exclusive (<80 MeV)
20.034.0)combined( f
peak? J/ψ under the are γJ/ψχmany How c
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 )
c
)(J/pT
25Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
)/(pand)(:J/ψonfitsKinematic T J Events with EM shower
Good fits to mumu kinematics with only chi_c’s, if EM shower
cut MeV 80 above J/ψ cedphotoprodu No
26Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
EmEt spectrum with J/psi mass cut:
Empirical functional form:
TC.EBTT e.E.A)f(E
Fit shown (ET in MeV): A = 0.00025B = 2.5C = 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)
27Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
Run,Evt: 220182.13272933M=3.101, pT=1.54, dphi=2.18
Note: CLC and BSC all empty although we did not require that.
CLC E empty CLC W empty
BSC empty
CENTRAL DRIFT CHAMBERCALORIMETERS: LEGO PLOT
/J
28Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
Summary of Results
29Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
Summary of Results
0.202)J/(B2,J),3516(
0.013)J/(B0,J),3415(
c
cAssumedSuppressed byJ_z=0 rule
nb 0.8)(3.0
30Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
Odderon O, C = -1 partner to IP … at least 3 gluons
In QCD but not yet observed.
Possibly O + IP & /J )2(' S
Search for Odderon exchange
Signature: Excess of exclusive & and Upsilons Yover rate expected from photoproduction (tuned to HERA data).t(p)-distribution would be flatter and henceVM should have larger <pT> andKinematic behavior different, but not well known. not known
)(
/J )2(' S
31Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
e.g. Schafer and Szczurek: arXiv:0705.2887 [hep-ph]
Some predictions for J/psi photoproduction:
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
Tak
e 3.
0 +
- 0.
8
We are consistent, & sowe can put a limit on odderon exchange.If theory gets more precise, our limit can change
32Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
c.l.)%95(38.0
19.019.1)combined,(
21.015.1)'(
41.032.1)/(
VIP
VIPO
Vtheory
dataR
theory
dataR
Jtheory
dataR
015.0060.0)3415(
/)(
0
cIPIP
JIPO
Odderon Limits and ratios
33Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
Invariant Mass Distribution - Upsilon Region
Invariant Mass (nassoc_tracks = 0)pT(μμ) < 6GeV/c
CDF Run II Preliminary
CDF Run II PreliminaryTrigger: μ+μ- |η|<0.6 , pT(μ) > 4 GeV/c
Inclusive
Photo-production of Y, Y’(first observation in hadron-hadron)
Y(1S)
Y(2S)
34Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
Exclusive Upsilon(1S) candidate Run/Event: 204413/8549136
R-z, Muon hitsLego, threshold ET > 10 MeV
Plugs, Miniplugs, CLC, BSC empty
M ~ 9.4 GeV
35Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
We have observed a candidate exclusive eventwith M ~ 64 GeV, which appears to be exclusive.
Run 166529 Event 10107956
Forward counters both sidesCLC and BSC were empty.Roman pot had pbar track
This is exactly the type of event for calibrating p(FP420)
GeV13.0)excluding(
GeV/c64~)( 2
TE
M
Search for Exclusive Z, and observe high mass lepton pairs.
Spectrum extends to M(ll) > 100 GeV!
36Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
FP420 : Forward Protons 420m downstream of CMS & ATLAS
CMS
CMS: Inner Vacuum Tank insertion
420 & 220m 220 & 420m||| ||| ||| |||ATLAS
37Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
Summary
bcJee ,,,',/,,
We have observed the following exclusive states X in p + X + pat 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.
IP+IP c within theoretical uncertainties, and demonstratesthat exclusive H should happen, if H.
Furthermore, exclusive di-leptons provide a calibration of forward p – spectrometers, momentum scale and resolution
38Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
BACK UPS
39Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
μ)(eachη21 Cosmic rays would be at 0
40Mike Albrow Fermilab ISMD 2008, Sept 2008Central Exclusive Production at the Tevatron
H[ ](M ), s = 14 TeVpp p H p
What is exclusive H cross section?
H
Calculation involves:gg H (perturbative, standard, NLO)Unintegrated gluon densitiesProb.(no other parton interaction) (“Gap survival”)Proton form factorProb.(no gluon radiation no hadrons) Sudakov Suppression
( ). ( ')i ig x g x
Durham Gp: Khoze, Martin, Ryskin, Stirlinghep-ph/0505240 ++
~ 3 fb (M(H)=125 GeV)
“factor ~ 3 uncertainty”
30 fb^-1 ~ 100 Ae events(Ae = acceptance, efficiency)
But other estimates differby “large” amounts!Need to “calibrate” theory!
Exclusive
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