# Presentation: 272771

##  Exclusive Dilepton (e+e-,+-,J/, ',)

-  Exclusive Dilepton (e+e-,+-,J/, ',)
- and Diphoton Production at CDF II

**James L. Pinfold**
**University of Alberta**
**HIGH ENERGY PHOTON COLLISIONS AT THE LHC**

-  MENU: CDF  Motivation    e+e-    ******    ********+********-**,J/,',   ******c**    Odderon    Conclusions

- James L. Pinfold                  Workshop on High Energy  Photon Collisions at the LHC                  1

## CDF :: Introduction

**CDF :: Introduction**

- Roman Pots not used

- Muon Chambers

-     CDF Detector + Performance

- Luminosity delivered 3.7 fb-1 about 3 fb-1 of data to tape

-  MENU: CDF  Motivation    e+e-    ******    ********+********-**,J/,',   ******c**    Odderon    Conclusions

- James L. Pinfold                  Workshop on High Energy  Photon Collisions at the LHC                  2

## Motivation: for Exclusive Studies 

***Motivations to study exclusive lepton pair production:***
*Potential to improve luminosity measurements at LHC since the cross section is known to better than ~5 %*
*Can be used as a control sample for exclusive processes whose cross- sections are not well predicted (**************, Higgs, ...)*
*For example,  a place to search for ******c**** and the odderon *
*Can be used to calibrate forward proton spectrometers (FP420) at LHC (important in the search for new physics & Higgs in exclusive channel)*
***Main motivation to study exclusive pp************ p + ************  + p ***
*This process is a “standard candle” for exclusive Higgs production*

**J/********',******

***q-loop***

-  MENU: CDF  **Motivation****  **  e+e-    ******    ********+********-**,J/,',   ******c**    Odderon  Conclusions

- James L. Pinfold                  Workshop on High Energy  Photon Collisions at the LHC                  3

##     Exclusive e+e- Production (1)

*Central state produced via                                                                          QED  **** **** e**+**e**-*
*Protons do not dissociate*
*Only e**+**e**-** are produced **** nothing else*
*Process has never been observed before in                            hadron-hadron collisions*

***QED***

-  MENU: CDF  Motivation    e+e-    ******    ********+********-**,J/,',   ******c**    Odderon    Conclusions

- James L. Pinfold                  Workshop on High Energy  Photon Collisions at the LHC                  4

##     Exclusive e+e- Production (2)

***Integrated luminosity → 532 ± 32 pb******-1***
***DIFF_DIPHOTON Trigger:***
*2 EM clusters with E**T**>4GeV plus a veto on BSC 1 (E+W)*
***Exclusive e******+******e******-****** events are selected by:***
*Reconstructing the e**+**e**-*
*Requiring that there is no other activity in |****|<7.4 *
*Photons have E**T** >5 GeV and |h| < 2*
*16 e****+****e****-**** candidates selected*
***Backgrounds 1.9 ******± 0.3****** events:***
*dijet fake ( 0.0 +0.1 -0.0)*
*cosmic ( negligible)*
*inclusive distribution (0.3+/-0.1)*
*dissociation  (1.6 ****±**** 0.3) (these are also gg ****e**+**e**-** where one (or both) proton(s) dissociate)*

-  MENU: CDF  Motivation    e+e-    ******    ********+********-**,J/,',   ******c**    Odderon    Conclusions

- James L. Pinfold                  Workshop on High Energy  Photon Collisions at the LHC                  5

##     Exclusive e+e- Production (3)

***Kinematics of 16 event candidate sample match the predictions of the LPAIR  signal MC**** (J.Vermaseren. Nucl. Phys., B229 347-371, 1983 )- e**+**e**-** are collinear in ****and have matching E**T*
***Cross-section for ****************** e******+******e*****-  *****LPAIR theory:****                                                  **	**	**	**LPAIR **= 1.71 ± 0.01 pb*

-  MENU: CDF  Motivation    e+e-    ******    ********+********-**,J/,',   ******c**    Odderon    Conclusions

- James L. Pinfold                  Workshop on High Energy  Photon Collisions at the LHC                  6

##     Exclusive e+e- Production (4)

***Agrees with LPAIR theory:****                                                  **	**	**	**LPAIR **= 1.71 ± 0.01 pb*
***Probability of 1.9 ********* ****≥*****16 = 1.3×10******-9****** - corresponds to 5.5*********** *****“observation”***
***This is the first observation of exclusive two-photon produced e******+******e******-****** interactions in hadron-hadron collisions  ***
*The LHC can rely on measuring such  processes for luminosity measurement, etc.*

*We have many more candidates in new data with dedicated 2-EM shower trigger*

-  MENU: CDF  Motivation    e+e-    ******    ********+********-**,J/,',   ******c**    Odderon    Conclusions

- James L. Pinfold                  Workshop on High Energy  Photon Collisions at the LHC                  7

##   Exclusive  Study (1)

***Exclusive ************ events:***
*selected in the same way as e**+**e**-** (except tracking)*
***Selected in the same way as ******************e******+******e******-**** (except tracks) agreement of ******** ****e**+**e**-** cross section gives confidence in analysis methodology*

-  MENU: CDF  Motivation    e+e-    ****** ****   ********+********-**,J/,',   ******c**    Odderon    Conclusions

- James L. Pinfold                  Workshop on High Energy  Photon Collisions at the LHC                  8

- where *X* has *J**PC** = 0**++*

**X**

##          Exclusive  Study (2)

***3 candidate events are found in 532 pb-1 of Run II data.***
***Background 0.09 ± 0.04 events (dominated by misid. of  excl.) ***
***Good agreement on kinematics  with ExHume MC ****(Monk & Pilkington. hep-ph/0502077)*
***0.8 ******+1.6******-0.5  ******events predicted from ExHuME MC ****-2 candidates are almost certainly **** but the  ************ hypotheses cannot be excluded*

-  MENU: CDF  Motivation    e+e-    ****** ****   ********+********-**,J/,',   ******c**    Odderon    Conclusions

- James L. Pinfold                  Workshop on High Energy  Photon Collisions at the LHC                  9

##     Exclusive  Candidates (1)

* **We have found >10 more candidates in new data with new di-EM shower trig.*

**Possible ************************ event**

-  MENU: CDF  Motivation    e+e-    ****** ****   ********+********-**,J/,',   ******c**    Odderon    Conclusions

- James L. Pinfold                  Workshop on High Energy  Photon Collisions at the LHC                  10

## The upper limit of the cross-section pp --> p  p is  set at 410 fb with 95% confidence level ( taking into account the background + its uncertainty,  signal selection efficiency, & Lint)
If 2 of the 3 candidates are  events we obtain a cross section:

*If 2 of the 3 candidates are  ****events we obtain a cross section:*

-     Exclusive  Candidates (2)

**Durham Group Khoze, Martin, Ryskin & Stirling  **
**hep-ph/0507040 Eur.Phys.J C38 (2005) 475 : **
**38 fb with factor ~ 3 uncertainty**

-  MENU: CDF  Motivation    e+e-    ****** ****   ********+********-**,J/,',   ******c**    Odderon    Conclusions

- James L. Pinfold                  Workshop on High Energy  Photon Collisions at the LHC                  11

##     Exclusive  Production (1)

***Trigger (DIFF_CHIC_CMU1.5_PT1.5_TRK):***
*BSC Gap, east & west*
*muon + track (p**t** > 1.3; |****| < 1.2)*
* **2.7 < M(muon + track) < 4.0 GeVc**2*
*No other activity in the events (to an |********| of 7.4)*
*The existing sample corresponds to a luminosity 1.48 fb**-1*
*Also higher mass muons have just been stripped, (trigs with p****t****(********) > 4 GeV, 2 muons, no Df requirement).*
*Should be very efficient for dimuons, with M >~ 9 GeV, covering the Upsilon region and above.*

-  MENU: CDF  Motivation    e+e-    ******    ********+********-**,J/,',   ******c**    Odderon    Conclusions

- James L. Pinfold                  Workshop on High Energy  Photon Collisions at the LHC                  12

##   Exclusive  Production (2)

*Example exclusive ****+****- **event:                        Run 199559, Event 13120174 *

-  MENU: CDF  Motivation    e+e-    ****** ****   ********+********-**,J/,',   ******c**    Odderon    Conclusions

- James L. Pinfold                  Workshop on High Energy  Photon Collisions at the LHC                  13

##   Exclusive  Production (3)

***Integrated luminosity – 1.48 fb******-1***
***Offline cuts***
*Loose quality cuts*
*P****T****(********) > 1.4 GeV/c & |********(********)| < 0.6 *
*Cosmic ray cuts (abs (delta_TOF) < 3 ns)*
*Exclusivity cuts (same as for the e****+****e****-**** paper)*
***Analysis of cuts is underway***
*Acceptance*
*Efficiency*
*Effective luminosity*
***STARLIGHT Monte Carlo simulation employed (S. Klein & J. Nystrand)***

-  MENU: CDF  Motivation    e+e-    ****** ****   ********+********-**,J/,',   ******c**    Odderon    Conclusions

- James L. Pinfold                  Workshop on High Energy  Photon Collisions at the LHC                  14

##   Exclusive  Candidates (1)

*We expect to increase the number of  candidates after review of the cuts*

-   Exclusive  Candidates (1)

-  MENU: CDF  Motivation    e+e-    ****** ****   ********+********-**,J/,',   ******c**    Odderon    Conclusions

- James L. Pinfold                  Workshop on High Energy  Photon Collisions at the LHC                  15

**Continuum**

##   Exclusive  Candidates (2)

*Good agreement on kinematics  with STARLIGHT  MC (Klein & Nystrand )*

*The   ************************** continuum*

-  MENU: CDF  Motivation    e+e-    ****** ****   ********+********-**,J/,',   ******c**    Odderon    Conclusions

- James L. Pinfold                  Workshop on High Energy  Photon Collisions at the LHC                  16

## Exclusive c Production Background

*Similar selection as ********** search with additional single isolated EM shower req.*
*10 candidates in 93 pb**-1 **of data*
*Many more  candidates with new trigger*
*New ChicMC (James Stirling)*
*ExAnalysis  in the doldrums after Angela Wyatt left for industry*
*It is just now being actively worked on...watch this space *
*Problem is - understanding low energy photon background*
***Many more events  with new trigger***

-  MENU: CDF  Motivation    e+e-    ****** ****   ********+********-**,J/,',   ******c**    Odderon    Conclusions

- James L. Pinfold                  Workshop on High Energy  Photon Collisions at the LHC                  17

## Find Exclusive events using 
Number of associated tracks = 0
Kinematics:   180o, pT  0, (or PT  0)
Trigger: 2 central muons with pT > 4 GeV/c
L = 890/pb-1 ~ 2.3 M events.
Remove cosmic rays (timing + colinearity)
Require on beam-line. Count additional (associated) tracks (n_ass) within 5 cm of   vertex.
Cleanliness, backgrounds & acceptances being studied.
Number of events “reasonable” for QED process & Lumi.

*Find Exclusive events using *
*Number of associated tracks = 0*
*Kinematics: ********** ********** 180****o****, ********p****T**** ******** 0, (or ****P**T** ******** 0)*
*Trigger: 2 central muons with p**T** > 4 GeV/c*
*L = 890/pb**-1** ~ 2.3 M events.*
*Remove cosmic rays (timing + colinearity)*
*Require on beam-line. Count additional (associated) tracks (n_ass) within 5 cm of  ********** vertex.*
*Cleanliness, backgrounds & acceptances being studied.*
*Number of events “reasonable” for QED process & Lumi.*

-  MENU: CDF  Motivation    e+e-    ****** ****   ********+********-**,J/,',   ******c**    Odderon    Conclusions

- James L. Pinfold                  Workshop on High Energy  Photon Collisions at the LHC                  18

## Exclusive Candidates (High Mass) (2)

- Clearly visible peaks
- Y(1s) and Y(2s),
- perhaps Y(3S) too.
- + continuum

**(n****assoc_tracks**** = 0)**

**Exclusive *****candidates***

- Exclusive Candidates (High Mass) (2)

-  MENU: CDF  Motivation    e+e-    ****** ****   ********+********-**,J/,',   ******c**    Odderon    Conclusions

- James L. Pinfold                  Workshop on High Energy  Photon Collisions at the LHC                  19

******(1s)**

******(2s)**

******(3S)?**

**Continuum**

**Continuum**

## Exclusive Candidates (High Mass) (3)

**Run/Event: 204413/8549136**

- Lego, threshold ET > 10 MeV

*Now apply “super clean” exclusivity cuts as in low mass      *
*l**-pair mass i.e. no pile-up, and only ****-pairs detected *

***145 events in 8 – 12 GeV region ***
***6 events + 4 M( ************) > 12 GeV.***
***(Most of reduction is killing pile-up)***

**Superclean Upsilon**

-  MENU: CDF  Motivation    e+e-    ****** ****   ********+********-**,J/,',   ******c**    Odderon    Conclusions

- James L. Pinfold                  Workshop on High Energy  Photon Collisions at the LHC                  20

- Exclusive Candidates (High Mass) (3)

##  Exclusive Di-leptons – a Good Place to Search for the Odderon

*In perturbative QCD the lowest order prototype of the pomeron is the color neutral system of two gluons. *
*The odderon is the C-odd partner of the pomeron - the hard odderon skeleton consists of three gluons in a color neutral state. *
*Global fits of the available hh and hh-bar data seem to establish that HE scattering dominated by exchange of the C = P = +1 Pomeron.*
*If the Odderon exists it would contribute to the exclusive J/******** and ******** **' **signal and be part of our signal *
*The Odderon would contribute to J/********, **********'****, ********** ****peaks u**nlike the ********c** background*

-  MENU: CDF  Motivation    e+e-    ****** ****   ********+********-**,J/,',   ******c**    Odderon    Conclusions

- James L. Pinfold                  Workshop on High Energy  Photon Collisions at the LHC                  21

##               Conclusion

*The paper on the observation of  exclusive p-p**** ******p + e**+**e**-** + p  production has been published in  PRL (March 2007) *
*Studies continue with new low E**T** di-photon trigger*
*The study of exclusive  p-p**** p** **+** **** **+** **p production  was published in   PRL (December 2007)*
*Studies are continuing  with a new low E**T**  di-photon trigger** (**E**T**>3GeV)*
*The study of p-p**** p +** ********** **+** p, J/****, J/**** **'**, ********,  is underway *
*Implications for the LHC  *
*Use of**** ************************************ /**e**+**e**-** as a luminosity monitor**  *
*Study of**** ******************** g-p **** ****** ********** **as a calibration for FP420 is underway *
*Exclusive study of p-p**** **J/****, ****’,...**** ********** **is a good place to search for the odderon*
*The process p-p******/****c** **is a standard candle for the exclusive Higgs*
*We are understanding how to use the LHC as a** ****, ****-p (**** **IP) & **IP- IP** collider*

-  MENU: CDF  Motivation    e+e-    ****** ****   ********+********-**,J/,',   ******c**    Odderon    Conclusions

- James L. Pinfold                  Workshop on High Energy  Photon Collisions at the LHC                  22

##                 Extra Slides

##   Tevatron Performance

-   Tevatron Performance

- Collider Run II – anticipated  67 fb-1 by end FY09
- with 2010 running 7 9 fb-1

## Motivation: for Exclusive Studies (1)

- We are looking at *exclusive* channels to study:
- LHC as a  collider -  exclusive production models for new and SM  physics
- Measurement of luminosity at the LHC &
- Calibration of  forward detectors (FP420)  using *** **** **l**+**l**-*
- LHC as a p collider higher energy reach & luminosity yield than for γγ case
- Experimental techniques to select exclusive events at the LHC
*Advantages: *reconstruct  mass of central state  *(if protons tagged)*

- Related measurements:

- In Heavy Ion Collisions:
- A. Belkacem et al., Phys. Rev. A 56, 2806 (1997);
- C. Vane et al., Phys. Rev. A 50, 2313 (1997);
- R. Baur et al., Phys. Lett. B 332, 471 (1994);
- J. Adams et al., Phys. Rev. C 70, 031902 (2004).

- In pp Collisions:
- D. Antreasyan et al., CERN-EP/80-82 (1980).

- In ep Collisions:
- ...

## Motivation: for Exclusive Studies (2)

*****W**+**W**-*
***** **tt*
*****H*

- Beyond SM:
*****H**+**H**-*
******
*****S**+**S**-*

- ~1% of pp
- luminosity

- Number of Higgs events for _single_ tags and assuming
- integrated luminosity of 30, 0.3 and 0.03 fb1 for *pp*, *pAr* and *ArAr* collisions, respectively.

- hep-ex/0009065

- Reconstruct central state using FP420

## Motivation: for Exclusive Studies (3)

- Exclusive Diffraction:

- where *X* has *J**PC** = 0**++*

*Two significant advantages over inclusive case:*
*mass of ****X**** can be determined from outgoing protons*
*‘**measures’ the quantum numbers of ****X***
*Exclusive channels we are looking at involve photons:*
********* ****- very ‘clean’ signature, but low cross section*
*This channel is a Standard Candle for exclusive DPE Higgs prod.*
*	**(**Calculations of V.Khoze et al., show that pomeron-pomeron cross-sections for Higgs production are a few times larger than for the **** case)*

## Central  Exclusive 2-Photon Production

- KMR+Stirling hep-ph/0409037
**QCD diagram identical to pHp**

**38 fb**

_***Central  Exclusive 2-Photon Production***_

**MGA et al. (2001) hep-ex/0511057**

**Tevatron**

- Claim factor ~ 4 uncertainty

**Cleanest test of p+H+p theory**

##   Exclusive e+e- Study Results

- 4 backgrounds are considered:

- Jet Fakes:			0.0+0.1-0.0 events
- Cosmics:			negligible
- Inclusive (QCD) events: 	0.3 ± 0.1 events
- Dissociation events:		1.6 ± 0.3 events

-    Efficiency

- Electron ID:			(26 ± 3) %
- Cosmic Rejection:		(93 ± 3) %
- Final State Radiation: 		(79 ± 5) %
- Exclusive Cuts:		8.6 %

***measured** **= 1.6(stat)±0.3(sys)pb*

*Agrees with LPAIR theory:**  ****LPAIR** = 1.71 ± 0.01 pb*

*corresponds to 5.5****observation”*

##               The Odderon

*The color neutral gluon systems, exchanged at high energy scattering processes, can be classified wrt  their C parity. The most important one is C-even system with quantum numbers of vacuum i.e. the pomeron. *
*In perturbative QCD the lowest order prototype of the pomeron is the color neutral system of two gluons. *
*The odderon is the C-odd partner of the pomeron - the hard odderon skeleton consists of three gluons in a color neutral state. *
*One would naively expect a suppression by a power of the coupling constant s for the additional gluon). It is not clear, however, why the contribution of the odderon is so small that it has not been definitely observed by any experiment.*