# Presentation: 711901

## Evolution: Search in High Mass Dilepton Channel in CDF

- Pre Run I
- Run 1A, Run 1B,
- and Run II......
- Kaori Maeshima
- Fermilab
- at Waseda University, Jan 12, 2005

## Why Search in Dilepton (ee, ) channel?

- Theoretically: Interesting physics  -- many different theoretical predictions
- Experimentaly: relatively small and well understood background.

- Discovery Potential!

- Dilepton invariant mass (M(ll))

## Why Search in Dilepton (ee, ) channel?

- Theoretically: Interesting physics  -- many different theoretical predictions we can test/search in this dilepton channel.
- Extra dimension solutions to the Hierachy problem
- Z'  (higher gauge structure, -> U(1) ), E6, little Higgs model Z', SO(10), etc., etc....
- Technicolor model (T, T)
- RPV SUSY s-neutrino
- lepton-quark compositeness
- .....

## Why Search in Dilepton (ee, ) channel?

- Experimentaly: relatively small and well understood background.

**ee**
- 2 two isolated e, ET > 25 GeV
- 2 central e (CC)
- or 1 central and 1 forward e (CP)
- missing Et significance < 2.5

****
- 2 isolated  PT>20 GeV
- |1|<1, |2|<1.5
- Cosmic ray rejection cuts

- Selection cuts

## High Mass Dielectrons

- CC+CP

- _High Mass Dielectrons_

**Total of ~ 12500 dielectron candidates in 200 pb****-1**** data**

## High Mass Dimuons

***High mass dilepton spectra is consistent with background prediction***

**Total of ~ 7500 dimuon candidates in 200 pb****-1**** data**

## CDF (D0) Z' Published Papers

- CDF: “Measurement of the e+e- invariant-mass distributions in pbarp collisions at root-s = 1.8 TeV”, PRL 67, 2418 (1991)
- CDF: “Search for new gauge bosons in anti-p p collisions at root-s = 1.8 TeV”, PRL 68, 1463 (1992)
- CDF: “Search for new gauge bosons decaying into dielectrons in anti-p p collisions at root-s = 1.8 TeV”, PRD 51, 949 (1995)
- CDF: “Search for new gauge bosons decaying into dileptons in anti-p p collisions at root-s = 1.8 TeV”, PRL 79, 2192 (1997)
- D0: “Search for additional newtral gauge bosons”, PLB 385, 471 (1996)
- D0: “Search for heavy particles decaying into electron positron pairs in p anti-p collisions”, PRL 87, 061802 (2001)

## CDF (D0) Z' Published Papers

- CDF: “Measurement of the e+e- invariant-mass distributions in pbarp collisions at root-s = 1.8 TeV”, PRL 67, 2418 (1991),1988-1989 data, 4.05 pb-1, ee only, 387 Gev sm limit, compositness, 1310 fb limit.
- CDF: “Search for new gauge bosons in anti-p p collisions at root-s = 1.8 TeV”, PRL 68, 1463 (1992), 1988-1989 data, 4 pb-1, ee and , 4 E6 models, 412 GeV sm limit, compositness limits, 1000 fb limit
- CDF: “Search for new gauge bosons decaying into dielectrons in anti-p p collisions at root-s = 1.8 TeV”, PRD 51, 949 (1995), 1992-1993 data, 19.7 pb-1, ee only, 6 E6, 350 fb limit (> 350 GeV), 505 gev sm limit
- CDF: “Search for new gauge bosons decaying into dileptons in anti-p p collisions at root-s = 1.8 TeV”, PRL 79, 2192 (1997), 1992-1995 data, 110 pb-1, ee and , 690 sm limit, 40 fb limit, 6 E6 limits.
- D0: “Search for additional newtral gauge bosons”, PLB 385, 471 (1996), 1992-1993 data, 15 pb-1, 490 GeV sm limit, (sigZ'/sigZ) = 2.2*10-3, using sigZ(ee) = 218 pb (measuments of W and Z boson production cross section (run 1A) , phys rev D 60, 052003, 1999, then, sigZ' limit = 480 fb
- D0: “Search for heavy particles decaying into electron positron pairs in p anti-p collisions”, PRL 87, 061802 (2001), 1992-1996 data, 124.8 pb-1 TC, Z', Z'sm limit below 670 GeV, ~70 fb limit

- 148 

- 406 ee

- 7234 ee
- 2566 

- 1371 ee

## Summary: CDF/D0 Z' results

- _Summary: CDF/D0 Z' results_

- 50 times data, 50 times better cross section limit, but...

- mass limits improve very slow
- because  dropps very fast.

## prospect of the search

- 50 times data, 50 times better cross section limit, but...

- mass limits improve very slow
- because  dropps very fast.

-  Tevatron performance and prospect of Int. luminosity and it's affect for the search
-  More Center of Mass Energy                    LHC

## Status: Current CDF Data Taking

- Intial Luminosity vs Store Number

- June 2001

- RUN II

- 2002

- 2003

- 2004

- 2001

- Jan. 2005

- Going up
- Dips (shutdowns)
- #stores/year
- 1240 (2002)
- 770 (2004)

## Status: Current CDF Data Taking

- Intial Luminosity vs Store Number

- June 2001

- RUN II

- 2002

- 2003

- 2004

- 2001

- Jan. 2005

- Going up
- Dips (shutdowns)
- #stores/year
- 1240 (2002)
- 770 (2004)

- Main cause of the sharp rise in the peak luminosity in 2004:

- _alignment_

- a huge difference in ave. store hours (much more stable operation).
- allow enough time to accumulate large stack of pbars

## Status: Current CDF Data Taking (cont.)

- Int. Lum vs Store Number

- June 2001

- RUN II

- 2002

- 2003

- 2004

- 2001

- Jan. 2005

- Going up sharper
- Flats (shutdowns)
- #stores/year
- 1240 (2002)
- 770 (2004)

- Delivered

- To tape

- ~ 500 pb-1 on tape

## Status: Current CDF Data Taking (cont.)

- Data taking Efficiency vs Store Number

- June 2001

- RUN II

- 2002

- 2003

- 2004

- 2001

- Jan. 2005

- Going up in 2002
- Spreads, consistency
- Dips
- beam cond.
- w/wo Silicon
- Effort to sustain
- #stores/year
- 1240 (2002)
- 999 (2003)
- 770 (2004)

## Luminosity and Efficiency during a typical store

- run 182514
- 2004.05.09
- 57e30 lum begin
- 13e10 lum end
- 26 hours store
- 2.4 pb-1 delivered
- 2.1 pb-1 to tape
- 85% efficient

- The same duration of time at the beginning or
- the end of the store corresponds more than 3
- times difference in luminosity.

## Operation is easier with the longer store hours

- The same duration of time at the beginning or
- the end of the store corresponds more than 3
- times difference in luminosity.

- There are much more chance things go wrong at the beginning of the store.
- luminosity is high
- high noise
- high trigger rate
- start of a run after no beam period.

- Ops person comes to the conrol
- room beginning of each store.
- >30 hour store vs < 20 hours
- (shot setup ~ 3 hours).

## Status: Current CDF Data Taking (cont.)

- Delivered and CDF Acquired Luminosity per FY in RUN II

## What to expect in FY2005 - 2009

- summer 04 shutdown: electron cooling installed in the recycler
- FY05 run: commitioning electron cooling ( no gain from it, yet)
- summer 05 shutdown: 2 major items planed
- 		- D0 run 2B upgrade
- 			* L00 tracker
- 			* complete trigger upgrade
- 		- Reconfig C0 for BTeV (quite a big job)
- 		- reconfig. Accumulator (electron cooling must be working
- 			for this.)  no more large stack after this.
- FY06 - FY 09: just take data with minor adjustment
- goal: 4.7 fb-1 (case: electron cooling not working) - 8.5 fb -1

## upgrade needed in CDF

- work in progress (modification are all to do with faster trigger-rate):
- 	SVT (~5 times faster readout. L2 rate: 250 - 800)
- 	Pulsar: running in pararell with alpha now
- 	XFT: reconfig.
- 	TDC: faster DSP code
- 	Event builder:  20 Mb/sec -> 60 Mb/sec
- 	pararell CSL

## prospect with 8.5 fb-1

- 1000/(8500/4) =  0.47 fb

- good limit, but better to find one.