# Presentation: 388220

## Perspectives in EW Symmetry breaking in Tevatron Run II

- Giorgio Chiarelli
- Istituto Nazionale di Fisica Nucleare
- Sezione di Pisa
- with the help of a lot of colleagues from CDF and D0

**HEP 2001, Budapest, July 2001**

## The Tevatron Run II

- Two possible interbunches:
-  396 ns for 36  bunches
-  132 ns for 108 bunches
- Average number of overlapping interactions in a  beam x-ing:
**N = 3** for Linst = 1x10**32** cm-2 s -1    @396 nsec
**N = 1** for Linst = 1x1032 cm-2 s -1  @132 nsec

-  Run II: s = 2.0 TeV
-  Two data taking periods:
-  Run IIa Lint=2 fb-1
-  Run IIb Lint=13 fb-1

## CDF Run II Upgrades

- new front-end,DAQ
- trigger
- new L1  track trigger
- new L2 secondary vertex tracker (SVT)
- new silicon tracker
- 7 layers ||<2
- tracks up to ****=2
******b**=65% (per jet)
- top 1 bjet ****=85%
- top 2 bjet ****=42%
- new central tracker
- N**stereo**=N**axial**=48
****p**t**/p**t**<0.001p**t**
- Time of flight
- new plug calorimeter
- ,e id to |****=2

**Z********ee**

## D0 Run II Upgrades

- new trigger and DAQ
- new tracking system
- 2T magnetic field
- silicon vertex detector
- 8 layers fiber tracker
- preshower
- tracks!
- b-tagging and lepton id as good as CDF
- improved muon spectrometer
- plans to install a STT (secondary vertex trigger)
- w.r.t. Run I:
- Acc. for W,Z x2
- Acc. for VV x 3

## EW Physics in Run II

-      with 2 fb-1 we expect to see (*per experiment*)
- >3,000,000 W's (e and )
- a few thousands V****
- several hundreds VV (WW,WZ,ZZ)
- O(10,000) ttbar pairs (hundreds of Dil events)
- Higgs (some more fb-1 needed...)
- > 300 pages in written reports
- Hard choices for this talk
- but I found a lead:
- a W mass determination with Mw< 30 MeV/c**2**
- supplemented by a M**top** determination by 3 GeV/c**2**
- could lead to a M**Higgs** determination to ****30%
- truth is in the masses
- and I will follow this with little deviations

## W Mass uncertainties

- In Run I:
- 80.433****0.079 (CDF)
- 80.483****0.084 (D0)
- 80.448****0.06 (comb.)
- syst. gov.d by size of control samples
- l+l- used for lepton energy scale(J/******,******)
- PDF (W asimmetry)
- PTW measured by PTZ

- In Run II:
- larger statistics in control samples will reduce experimental systematics

| Source | uncert.
(MeV/c2) |
| --- | --- |
| Fit statistics | 100 |
| Momentum scale | 85 |
| Recoil model | 35 |
| Background | 25 |
| Mom.resolution | 20 |
| Selection bias | 18 |

**CDF Run Ib W******** ******** data:**
**uncertainties scaling stat.**

## W Mass II

- In Run IIa we expect to reach:
- 40 MeV/c2 (e,**** chan.) *per experiment*
- deep knowledge of the detector
- increase in lepton coverage (CDF) and tracking (D0)
- goal: 30 MeV/c**2**
* **per experiment*

- ISL external
- support

- COT inner cylinder

- D0 Run I We

- 80.483**±**0.084 GeV/c**2**

## W and Z couplings

- Z sector:
- param. by ***h*** **V **coupling in Z****V(Z,****)vertex
****ee()**** ****
****ee() a few

**W sector: parametrized by ********k and ******** **
**scaled from Run I, per experiment**

**Z sector: h****V********in 1 fb****-1**

- Limiting to a few
- processes in the W sec:
- WW****l****l********
- WZ****lll********
- W****l********evts
- hints of "Zero Amplitude" @CDF

**1fb****-1 ****M.C. ********-********l**

**Tevatron in Run I**

| |h30| | <0.038 |
| --- | --- |
| |h40| | <0.0027 |

## Top Physics in Run II

- @******s=**2 TeV:
**** up by 40% wrt 1.8 TeV
- gg contribution up 15%
- top mass
- top properties
- x-section
- couplings(V**tb** in CKM)
- decays
- significant double b-tagged top events
- Jet en. scale (Z****bb)

| Run II expectations in 2 fb-1 |  |
| --- | --- |
| Channel | CDF/D0 |
| Dilepton(e,) | 155 |
| Dileptons() | 19 |
| Lepton+>=3 j | 1520 |
| Lepton+>=4 j | 1200 |
| l+>=3j+ 1btag | 990 |
| l+>=4j+2btag
 | 240 |

**Scaled from Run I**
*per experiment*

## b tagging 

- Run II:
- good d  resolution  (6pt m)
- extendedcoverage
****beam ****20 cm
- SVT trigger on displaced tracks
- most relevant for Higgs and for Z****bbar events

**D0 b-tagging per jet**

**beam position (in cm)**
** ****from SVT (online)**

## Top mass

- Run I (combined)
- 174.3±3.2(st.)±4 (syst) GeV/c**2 **
- syst dominated by statistics in control samples
- most of the weight due to l+jets sample

- In Run II:
- uncert. down to
- ±3 GeV/c**2 **(1 in 10fb-1)
-  most improvements from  jet energy scale:
- using W's and Zbb

| CDF l+jets Run I(II) syst. |  |
| --- | --- |
| Source | Gev/c2 |
| Jet en.scale | 4.4(2.2) |
| ISR and FSR | 1.8(1) |
| background  | 1.3(0.5) |
| b-tag bias | 0.4 |
| PDF | 0.3 |
| Total | 4.9(2.5) |

## Top couplings

- In Run I
- x-section determination
- V**tb** (indirect) ratio 0:1:2 b-jet in top events

- In Run IIa
- xsec uncert. <10%
- top FCNC
- S.M. B(t****Ws)(0.1%)?
- Vtb
- to 3% (indirect)
- to 15% (direct)
- W helicity:
- SM prediction= 69%for B(t****W**l**b)
- Run I=70.6±1.6%
- few %
- More ?
- Yukawa coupling:****t=m**t**23⁄4****G**F******1

|  | 1fb-1 | 10fb-1 |
| --- | --- | --- |
| B(tZq) | 1.510-2 | 3.810-3 |
| B(tq) | 3.10-3 | 410-4 |

## Single Top production

- Production of single top through Wg fusion and W* is about 1/3 of strong pair production (for mt=175 GeV/c2 @ s=2 TeV):
*W**-gluon fusion*:  (Wgtb+X)= 1.44 pb
*Virtual W*:  (W*tb+X) = 0.74 pb
- large uncertainties in the cross sections!
- Effective isolation of W* process** **will be tried at Tevatron:
- A V**tb** (direct) determination to 15% is feasible as cross section for this process  is proportional to |V**tb**|**2**

## Higgs and the Tevatron

- M**Higgs** < 130 GeV/c**2**.
- V+H (V=W,Z)V****ll
****V****jj large bck)
****(WH) 0.2 pb
****(ZH) 0.1 pb
- Mjj important, Higgs specific corrections developed

- For larger M**H**  gg****H becomes important as new decay channels open and background reduces

## Low mass region: VH in 15fb-1

- WH,H****bbar****W******l******
- e(****with E**T**(p**T**)>20 GeV
- E**T**>20 GeV
- two b-tagged jets
- residual bck: Wbb, tt, WZ, tb (single top)
- Non-physical bck. negligible
******mjj** important

- ZH,H****bbar**** Z********
- Had.energy<175 GeV/c**2**
- residual bck: Wbb, tt, WZ, tb (single top)

**In Red processes not measured in Run I**

## High mass region

- Focus on gg  HW*W*
- beat low x-sectl+l-****
- low background
- Add qq W(Z)H****W(Z)W*W* ****lllX (trilepton) mode
- main backgrounds: WZ,ZZ
- qq**** W(Z)H****
****W(Z)W*W* ****lljjX
- veto: no b-tagged jets
- main backgrounds: WZ,ZZ,tt
- Looks very hard to do, but the challenge will bring lots of people together

## Higgs before LHC ?

- Two experiments (CDF and DØ)
-  Band extends upward by 30% as an indication of uncertainties in:
- b-tagging  efficiency
- mass resolution
- systematic effects
- Results  by the "Run II Higgs Working Group"
- In 2 fb**-1** check 115 GeV/c**2** "hint of Higgs"

- Run 2 a

**Run 2 b**

## Can we (CDF&D0) get 15 fb-1 ?

- This should be done on a relatively short time basis (before LHC, as x-sections at 2 TeV probably will not allow Higgs physics)
- can be done with the Run 2a detectors?
- yes but we have to replace silicon
- do we need serious changes to the machine?
- yes, R&D in progress (electron cooling)

- At INP first e-cooling in 1974
-  at Tevatron experiment underway

## Conclusion

- Run IIa with 2 fb-1 will provide a chance to:
- Measure Mw to ±30 MeV/c**2**
- Measure Mtop to ±3 GeV/c**2**** **
- test TGCs with VV events
- use top to test SM and look for deviations
- with 15 fb-1 we will be looking for Higgs

**This plot reflects a conservative approach (we expect to do slightly better and this is one experiment only). Central values from Run I**