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Exclusive Central Production in CDF (From talk to CDF CM, apologies for obvious to you). where X is a simple state fully measured, and no other particles produced. (Cannot detect p/pbar, down beam pipe, but BSC → η = 7.4 empty). Motivation: - PowerPoint PPT Presentation
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1Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
Exclusive Central Production in CDF (From talk to CDF CM, apologies for obvious to you)
pXppp
where X is a simple state fully measured, and no other particles produced. (Cannot detect p/pbar, down beam pipe, but BSC → η = 7.4 empty)
Motivation:In CDF, sophisticated tests of QCD with large rapidity gaps ΔyLooking forward to LHC:Interesting examples ...,
~~,,, llWWHhX
If see h, H : Mass, width, spin J, C = +1, Couplings H – gg, …in a unique way, even if e.g. bb(150)&bb(140) Hh
In CDF, 5 PRLs:(M, GeV range) 80)/Z(40ll,χψ(2S),J/ψ/4),(3μμX
30)JJ(10),γγ(40),(10ee
c0
2Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
A bit of history:To show that σ(p+H+p) wasuncertain by a factor > 1000in 2000
We absolutely needed someexperimental input to home inon what to expect!
pJJppp
pppp
pppp
pppp
b
c
* Now measured in CDF*
*
*
3Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
pJJppp
pppp
pppp
pppp
b
c
Cleanest (no S.I.) but smallest σ
KMR: 38 pb in our box). 2+1 candidates
Clean, big σ:
but M(c) small (non-pert) & hadron
(KMRS) nb100~)0( ydy
d
More perturbative, smaller theory uncertaintyBut σ ~ 1/500th χc. Also BR’s not known!See next slide.
Big cross section, but least well defined (jets!)and largest background. ~ 100 pb for M(JJ) > 30 GeV
Our 3 measurements are all in good agreement
(factor “few”) with the Durham group predictions.
H JJ, ,χ ,χ γγ,
(980)fσ(600),
bc
0
4Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
Khoze, Martin and Ryskin, hep-ph/0111078, Eur.Phys.J. C23: 311 (2002)KMR+Stirling hep-ph/0409037
36 fb
-1T~ 40 events per fb with p (γ) > 5 GeV/c & |η| < 1.0
& much smallerqq
Exclusive 2-Photon Production
Tevatron
Claim factor ~ 3 uncertainty ; Correlated to p+H+p
H
Phys.Rev.Lett. 99,242002 (2007)
TE ( ) > 5 GeV; | ( ) | 1.0
3 candidates, 2 golden12Note : 2 10 !MEAS INEL
New data, Lower threshold, probable “observation”(Erik Brucken)
5Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
5
c0c
J/ψ
γ
μ+
μ-
& nothing elsein all CDF
-7.4 < |η| < + 7.4Beam Shower Counters BSC:Scintillator paddles tightly wrapped around beam pipes.Detect showers produced in beam pipes if p or p dissociate.e.g. 8 + 10 counters
If these are all empty, p and p did not dissociate (or BSC inefficient, estimated from data)but went down beam pipe with small (<~ 1 GeV/c) transverse momentum.
pp
4.7||2.5
CDFcentral
BSC (size greatly exaggerated!)
- 50 m
CDF measurement of exclusive c J/ψ + → μ+μ-
6Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
c has small pT, and so do muons: Trigger = 2 muons + BSC veto.pT(μ) >~ 1.4 GeV to escape calorimetry.M(μμ) <~ 4 GeV imposed by trigger rate (no prescale)
Offline required μ+μ- or μ+μ- and nothing else.Found most μ+μ- had no photon.
500
100 1000 counts
Example: BSC1 (8 PMTs)5.4 < |η| < 5.9Hottest PMT (no int/int)
0cc
pppp
2μμ
2 GeV/c 4MGeV/c3
pppp
Exclusive production (CDF)0c
7Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
arXiv:0902.1271
Fit: 2 Gaussians + QED continuum.Masses 3.09, 3.68 GeV == PDGWidths 15.8,16.7 MeV=resolution.QED = generator x acceptance3 amplitudes floating
402 events
pppp
8Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
e.g. Schafer and Szczurek: arXiv:0705.2887 [hep-ph]
Some predictions for J/psi photoproduction: Machado,Goncalves 3.0 nbMotyka and Watt: 3.4 +- 0.4 nbSchafer & Szczurek ~ 2.8 nbNystrand 2.7+0.6-0.2 nb
Our result: 3.92 +- 0.62 nbTak
e 3.
0 +
- 0.
3Y is much lower.Allow Pile-Up (x 10)More data (x 3)More Δy (x >4)
(95%) J/ψOIPfor nb 2.3 )(J/ 0y|dy
dσ
(CDF) nb 0.623.92)(J/ψ 0y|dy
dσ
average)(theory, nb 0.33.0)(J/ψ 0y|dy
dσ
Our limits on O-exchange are close to,and constrain, theoretical predictions
nb 0.46:Theory
nb 0.140.53 :CDF
:)]2('[|
0.110.04
0
Sdy
dy
9Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
Now allow photons: EmEt spectrum with J/ψ mass cut:
Empirical functional form
MC also estimates only few % of under the cut
(But CDF SIMulation is not reliable for such low ET)
65 events above 80 MeV cut.3 events below (estimated from fit)4% background under J/psi# = 65 +/- 8
4039:not do ψ(2S)
352286 :photons have J/ψ
γJ/ψχ c
cχ
γJ/ψχ c
10Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
)/(pand)(:J/ψonfitsKinematic T JEvents with EM shower
Good fits to kinematics with only , if EM showerμμ c
Confirms assignment
cχ
cχ
No photoproduced ψ’(2S) with EM shower > 80 MeV
11Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
Summary of Results pppp M = 3-4 GeV/c2
No strong evidence for odderon
90 nb(χ width)Durham
(IP)p(γγp TT
12Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
PDG 2008 (latest):
Could exclusive central production be a valuable lab for decays?
13Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
Dimuons: Upsilon Region
Invariant Mass 0 associated trackspT(μμ) < 1.5 GeV/c
CDF Run II Preliminary
CDF Run II Preliminary
Trigger: μ+μ- |η|<0.6 , pT(μ) > 4 GeV/c
Inclusive
Search for/measurement ofphotoproduction of Y, Y’(not before seen in hadron-hadron)
Status:analysis in progress.QED continuum checkY : cf HERA (we resolve states)Can we see ?
Y(1S)
Y(3S)
Y(2S)
γΥχ b
14Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
Exclusive Upsilon(1S) candidate Run/Event: 204413/8549136
R-z, Muon hits
Plugs, Miniplugs, CLC, BSC empty
M ~ 9.4 GeV
But will allow P-U,(except for b Y + search)
15Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
b at Tevatron and LHC nb, “O.M.”
hep-ph/0403218
MeV 777p)%;0.11.7()1S(:2J)10269(
MeV 242p)%;4.22.16()S2(:2J)10269(
MeV 743p)%;6.09.0()S1(:0J)10232(
MeV 207p)%;1.26.4()S2(:0J)10232(
MeV 442p)%;422()S1(:2J)9912(
391MeVp?);%5.3(~%6)S1(:0J)9859(
:states20and00JIχ
γb2
γb2
γb0
γb0
γb2
γb0
PCGb
Complex spectrum of radiativedecays to Y(1),Y(2):
Here just give DPE allowed states(J=0 >> J=2)
ds/dy(KMRS,TeV) = 200 pbIf BR = 4% (?) that’s 8 pb ->gY1Cf ~ 10 pb for ds/dy(Y1)ds/dy(KMRS, LHC) = 600 pbIf BR = 4% (?) that’s 24 pb ->gY1cf ~ 30 pb for ds/dy(Y1)
Will not get good Y cross sections without knowing , and p-calibration screwed up. “Soft” photons important.
b
16Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
Y: Predictions from Motyka and WattarXiv:0805.2113
Phys.Rev.D78:014023,2008.
W)&(M pb)145())1((| 0 Ydy
dy
(CDF)nb)62.092.3()/(| 0 J
dy
dy
Other predictions:12 +- 1 pb (Cox,Forshaw,Sandapan)~12 pb (Klein & Nystrand)0.8 – 5 – 9 pb (Bzdak,Motyka,Szymanowski & Cudell)
HERA data not much help:Resolution confuses Y1,2,3, low statistics
Factor ~ 400
CDF Run II
17Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
A. Szczurek: arXiv:0811.2488
/J
)2(' S
)1( S
)2( S
~ 30 pb
18Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
… and more so as M increases. CDF QED data:
M(mumu) = 3 – 4 GeV/c20.34 (rad) efficient.
M(ee) = 10 – 30 GeV/c20.08 (rad) efficient.
M(ll) = 40 – 76 GeV/c20.02 (rad) efficient.
)GeV/c(
rad)(1.12
M
is a good empirical fit to these QED data cuts.
0.13 for 8 – 9.2 GeV/c20.10 for 10.5 – 12 GeV/c2
How does resolution in compare CDF-ATLAS/CMS ?
QED γγ→l+ l-
19Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
M(ll) > 40 GeV/c2pT < 1.1 GeV/c efficient
M(mumu) = 3 – 4 GeV/c2pT < 0.3 GeV/c efficient.(- 3 outliers)
M(e+e-) = 10-30 GeV/c2pT < 1.6 GeV/c efficient.
pT(l+l-) cut dominated by detector resolution (so CDF not ~ CMS)True pT (Coulomb pair) < ~ 0.1 GeV/c.Looking at CDF data (small statistics in tail):
pT <~ 1.0 GeV/c2 should be efficient for 8 – 12 GeV/c2 region(a priori).
QED:
20Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
Photoproduction of vector mesons: larger
pT <~ 1 GeV/c efficient( - outliers)
< ~ 0.65 efficient
andpT
J/psi
psi(2S)
<~ 0.22 for Y(1)
21Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
Next steps:Full data set (~ x 2-3).Separate data in mass bands: QEDlow, Y1,Y2,Y3, QEDhigh, QED veryhigh.
Check all distributions & confirm cuts.Simulate generation and CDF detector Acceptance x efficiencyCross sections {& no dependence on L(instantaneous)?}
CDF Lumi calibration has ~ 6%. Can these QED events help improve it?? (Marginal, but test bed for LHC)
The Y1 Y2 and Y3 photoproduction cross sections could be better than HERA (resolution & statistics). Odderon contribution? Information on dipole-proton scattering, g(x1,x2), S^2 etc. But:
From “final” sample, select no pile-up clean events (~ 15%)Allow EM showers, look for: b
b
22Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
What about LHC and FP420 ?
The best tests of
)(
and)(
are)(
pppp
pppp
pHppp
b
These can probably only be done with no pile-up, orjust possibly with just 1 or 2 min-bias events (? … could try)Early days with low luminosity/bunch crossing:<n_inel> < ~ 3 Exclusive 2+3 EM showers can give us these.
pllppp
pllppp
)(
and
These will practice calibration of FP420 spectrometers(momentum scale and resolution).Y’s higher rate than QED. Want forward pairs for acceptance.
23Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
Level 1:2 EM clusters > 4 GeV (E or ET?) + Forward gapsLittle (<~ 4 GeV, or noise + x) E (ET?) in all hadron calorimeters.(In CDF this trigger worked with no prescale and no L2,L3.)
Higher level: Cleaner forward gaps, 1 vertexShould get low rate (<~ 0.1/s?) with no prescale.
Two muons with pT > 4 GeV/c and Forward gaps as well, want both
3~||
Key is good trigger in early:
Cross section at LHC Y, chi+b, QED,
FORWARD SHOWER COUNTERS: FSC
24Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
Y and FP420 at LHCPredictions from Motyka and WattarXiv:0805.2113
Phys.Rev.D78:014023,2008.
Large uncertainty in extrapolation.No gap survival probability!
leptons
T ep )()2(1
FP420 acceptance?
(most likely kinematics)
2121 ;GeV/c75.4TT pp
.)(max vsp
5.2 5
420
220
)(min p is always much too small to see.Fortunately each xi(p) is known
25Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
Photon “beams” radiated from electrons and protonsLEP etc: e+e- (~ background free)HERA: e p (more background, little done)pp/ ppbar: Very high b/g … Seen in CDF γ
e,p
ee
Phys.Rev.Lett 98,112001(2007)
2GeV/c)μM(μ
μμ
μμeeμμ
inel12σ103~pb0.24~σ
Tevatron as a collider!
PRL 102, 242001 (2009)
26Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
E not ET!
CLC BSC
M(ee) = 49.3 GeV/c2 |Δφ-π| = 6 mrad = 0.34 deg, pT(ee) = 210 MeV
M reach Tevatron >~ HERA, LEP !pb 0.256QED cf
pb 24.0
4||,GeV/c40
μμor )(
(LPAIR)
13.010.0
2
M
peeppp
27Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
Emily)(by LPAIRTeV,1.96sat
(max)||differentfor )(minM.vs
)( QED
pppp
Curves hand-drawn by me!No apologies for the quality!Can “read off” cross sectionFor any M_min orM-range, and eta(max).
Handy graph
√s = 1.96 TeV
28Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
All our dilepton measurements agree with QED: So what?
1) It shows we know how to select rare exclusive events in hadron-hadron environment2) No other h-h cross section is so well known theoretically except Coulomb elastic (inaccessible).
Possibly best possible Luminosity calibration at LHC e.g.3) Outgoing p-momenta extremely well-known (limited by beam spread). Calibrate forward proton spectrometers.4) Practice for other γγ collisions at LHC:
.,..~~
,WWγγ ll
2 |η| and GeV 10)μM(μ
withpb500in events 4400-
1
Luminosity calibration at LHC
29Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
LPAIR cross sections at LHC (Emily Nurse):
Have at Tevatron and LHC(14)(M in GeV):
4.2min
2.2max
minmaxmin )25.1480(~),(M
MM
Useful look up.
30Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
Exclusive Z production : CDF SearchAllowed in SM (like V)but ~ 0.3 fb (Motyka+Watt)
Could be enhanced by BSM loops
2.2/fb : 318K μμ&ee M > 40 GeV; 183K in Z window 82-98 GeVRequire no other interaction, no additional tracks, all calorimeters in noise (E)
8 with BSC empty
Interesting?!-IP-Z eff.coupling.ZOOM IN to see how!
LHC) @ (13fb
0.3fbTheory )σ(Z
C.L.) (95% pb 0.96)σ(Z
excl
excl
~ record E()
Search in “no-PU” events. Have 10 x data if PU allowed.
31Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
31
Exclusive Di-Jets Phys Rev D77:052004 (2008)
“Almost” exclusive di-jet,Two jets and nothing else
0.8JJ
CEN
M
M
(~ polar angle)
(azimuth) Transverse
Energy TE
JETJETelse nothing~ pJJppp
Observed in CDF, QCD tests& related to p+H+p
Interesting QCD: gap survival, Sudakov factor Nearly all jets should be gg …. qq suppressed by M(q)/M(JJ) (Jz=0 rule)
Gluon jet physics.
p JJ
GAP
JJJJ
X
MR = 1.0
M
32Mike Albrow FP420 Meeting, 6/20/09 Exclusive Central Production in CDF
SummaryIn p + p →p + X + p, t-channel exchanges only γ, {gg} (IP), or {ggg}(O) in L.O.
O has not been observed; we give best limitQED process (a) seen in e+e- and μ+μ-, M = 3 – 75 GeV/c2
In hadron+hadron, only CDF.Photoproduction (b) seen J/ψ, ψ’, Y(prelim), Z limit (only CDF)
Exclusive gg →χc measured, Excl.H must happen, σ constrained
Exclusive γγ candidates, and exclusive JJ support some theoretical calculations, refute others.
(a) (b) (c)
Best estimates now σ(p+p →p + SMH + p) ~ 1 – 10 fb @ LHCFeasible with v. high precision (space and time) p-detectors