# Presentation: 791735

## Recent Results from Tevatron

- Yuri Gershtein
*On behalf of CDF and DØ collaborations*

## Outline

-  Introduction
-  Status of the Tevatron and the Experiments
- Tevatron physics program
**New Results from the Energy Frontier!**
- Too many results to cover all – will select personal favorites...
-  A look ahead
-  Summary

- SEASAPS-2005: New Results from Tevatron

## Tevatron Status

- Current records
-  1.6 · 1032 cm-2s-1
-  21 pb-1 per week
- 1.4 fb-1 delivered
-  Compare to Run 1
-  0.25 · 1032 cm-2s-1
-  4.9 pb-1 per week
-  120 pb-1 recorded
-  Goals
-  ~8 fb-1 per experiment before LHC starts publishing physics papers

**Peak Luminosity**

**Integrated Luminosity **

- 24 pb-1/week

- 1.4 fb-1

- Dec 2001

- Oct 2005

- 1.6·1032 cm-2s-1

- SEASAPS-2005: New Results from Tevatron

## CDF Experiment

- SEASAPS-2005: New Results from Tevatron

## DØ Experiment

- SEASAPS-2005: New Results from Tevatron

## Standard Model

- Standard Model survived yet another year...
- Questions: Mass, Unification and Flavor
-  EW fits favor light Higgs
-  If Higgs is light – SM breaks at <100 TeV

- LEP EWWG Summer 2005

- Allowed

- hep-ph/9708416

- SEASAPS-2005: New Results from Tevatron

## Tevatron Physics Program

-  Electro-weak physics:
-  Top physics
-  W mass
-  Direct Higgs Search
-  New Phenomena
-  SUSY, ED, Exotics
-  B physics
-  BS mixing
-  Diffractive / QCD

- LEP experiments set a very high standard in co-operation between experiments and combination of results.

- CDF and DØ are stepping up to the challenge – a lot of combinations, similar analyses co-ordinate even before analyses are released to synchronize assumptions

- SEASAPS-2005: New Results from Tevatron

## B physics

- Bs mixing
*(CP violation, X(3872), B**c**, B******, D******,****b**, masses, lifetimes, etc...)*

## CKM Matrix

- Mass eigenstates and weak eigenstates for quarks are not the same – mass states are a mixture of weak eigenstates
- CKM is the mathematics behind the CP violation, but gives no insight about the nature of it
- Unitarity requirements can be visualized as triangles. Especially useful for                                       since all sides are about the same size

- Unitary matrix Cabbibo-Kobayashi-Maskawa
- 9 complex numbers - 4 parameters

- Measure all angles and sides – verify that they are consistent with a single triangle
- Test consistency of the SM

- SEASAPS-2005: New Results from Tevatron

## B-meson Mixing and Oscillations

- Analogously to the K-mesons, neutral B-mesons are a mixture of two CP eigenstates with different masses and lifetimes
- Bd mixing has been observed by ARGUS in 1987
- Observation of Bs mixing is another test of the CKM consistency
- Combination of Bd and Bs is even more important
- There are large theoretical uncertainties in m calculations (~20%)
- The uncertainty on a ratio, ms/md is much smaller (~3%)
- Currently, Tevatron is the only accelerator capable of producing BS

- SEASAPS-2005: New Results from Tevatron

## Bs production and tagging

- Bs production and tagging

- Need to reconstruct Bs meson and determine its initial and final flavor and proper decay time
- CDF has better resolution, DØ has better yields
- Main challenge is initial flavor determination (flavor tagging)
- Opposite side – lepton charge, lepton-jet charge, vertex charge
- Same side – charge of soft kaon from fragmentation

- SEASAPS-2005: New Results from Tevatron

## BS Mixing Results

- BS Mixing Results

- After reconstruction and tagging – determine proper decay time and look for flavour oscillation
- Good proper time resolution is essential
- For semileptonic decays the neutrino escapes and one has to estimate its momentum statistically
- For hadronic decay resolution is as good as your silicon – but statistics is much poorer

- SEASAPS-2005: New Results from Tevatron

## Prospects for BS Mixing Observation

- SEASAPS-2005: New Results from Tevatron

## Difference in Bs Lifetimes

- Difference in Bs Lifetimes

- The CP eigenstates not only have different mass, they have different lifetime – observation of lifetime difference is another test of CKM (and is indirect evidence for oscillations)
- How to measure lifetimes of CP eigenstates? Use final state with a certain value of CP: BsJ/ (l+l-) (K+K-)
-  meson is a vector, CP depends on polarization
- 2-dimensional analysis: polarization v.s. lifetime in BsJ/ 

- PRL 95, 171801 (2005)

- PRL 94, 101803 (2005)

- Both  measurements consistent with zero lifetime difference, but getting close to observation...

- SEASAPS-2005: New Results from Tevatron

## Electroweak Physics

- W, top mass and Higgs
*(anomalous coupling limits, top properties, etc...)*

## W Mass and Width

- W mass measurement is one of the single most important measurements for Tevatron to make
- it’s also THE hardest, especially at high luminosity
- so far – sensitivity studies with errors approximately the same as in Run I
- First step to W mass measurement is W width measurement
- Understand the Breit-Wigner tail of the Jacobian edge at MW

- W=2.01±0.14 GeV

- hep-ex/0510077

- electron channel only

- SEASAPS-2005: New Results from Tevatron

## Top Production and Decays

- Top discovered by CDF and DØ in 1995
- Tevatron is still the only place where top quarks are produced
- Quark annihilation – 85%
- Gluon fusion – 15%
- Top lifetime is smaller than hadronization time – top decays as a free quark!

- Br(tWb)  100%, final stated depend on how W decays
- Both W decays via Wl: 2 leptons, 2 b-jets, missing ET
- dilepton mode *- cleanest*
- One W decays via Wl: 1 lepton, 2 b-jets, 2 jets, missing ET
- lepton+jets mode *– one of the t’s can be fully reconstructed*
- Both W decay into jets:    2 b-jets, 4 jets
- all-jet mode *– largest yield, but very hard (both trigger and off-line)*

- SEASAPS-2005: New Results from Tevatron

## Top Mass Measurement

-             Template method
- Generate MC for many points in top mass and determine which fits the data best
- Lepton+jets channel:

**M****top**** = 173.5 +3.9/-3.8 GeV**

-             Matrix Element Method
- For each event match observed kinematics to the partons in the matrix element and find maximum of the likelihood, which provides the best measurement of top quark mass

- Main source of uncertainty – Jet Energy Scale
- “Calibrated” using jets from W in the signal events

- SEASAPS-2005: New Results from Tevatron

## Top Mass Prospects

- SEASAPS-2005: New Results from Tevatron

## New Top Mass World Average

- hep-ex/0507091

- SEASAPS-2005: New Results from Tevatron

## Indirect Higgs Constraints

- MH=91+45-32 GeV
- MH<186 GeV @95%CL

- SEASAPS-2005: New Results from Tevatron

## Direct Higgs Searches

- Main production mechanisms – gluon fusion and associated W/Z production
- Main decay modes – bb, for low mass, WW for high mass

- SEASAPS-2005: New Results from Tevatron

## Higgs Search Channels

- Associated production with W/Z

- Gluon fusion production

- MSSM Higgs – use enhanced b coupling

- H

- Wl + hbb             : lepton + 2b + MET
- Z + hbb             : 2b + MET
- Wl + hWWl l : 3 leptons + MET

- hbb is hopeless – background too large
- h                     : 2 taus
- hWWl l         : 2 leptons + MET

- hbb        : 4 b
- h         : 2 taus + 2 b – in the works

- SEASAPS-2005: New Results from Tevatron

## Limits are still orders of magnitude away from the SM prediction
But setting restrictive limits on models beyond the SM

- Limits are still orders of magnitude away from the SM prediction
- But setting restrictive limits on models beyond the SM

- Higgs Searches Summary

- SEASAPS-2005: New Results from Tevatron

## Higgs Discovery Prospects

- per experiment

- per experiment

- It’s possible to be lucky or unlucky!

- mH=115 GeV assumed

- From T. Junk’s  FNAL W&C

- SEASAPS-2005: New Results from Tevatron

## Beyond the Standard Model

- Supersymmetry
*(many other searches for Extra Dimensions, Z’, W’, LQ, excited quarks and leptons, etc...)*

## Gauge-Mediated SUSY

-     GMSB SUSY can manifest itself in final states with two photons and missing ET
- Couple of nice events, but no discoveries...
- DØ:  m(1+) > 195 GeV  *PRL 94, 041801 (2005)*
- CDF: m(1+) > 167 GeV  *PRD 71, 031104(R) (2005);*

- arXiv:hep-ex/0504004

- SEASAPS-2005: New Results from Tevatron

## Jets+Missing ET

- Squarks and gluinos produced by strong interaction, but cross-section is small because they are heavy
- Final state with jet(s) and missing ET
- Few interesting events, improving on LEP and Run I

- SEASAPS-2005: New Results from Tevatron

## Tri-leptons

- Gaugino production at Tevatron leads to signatures with three leptons in the final state
- Most promising signature for Tevatron
- Considered final states so far
- Same sign  (DØ)
- e+e+/e  (CDF)
- ++/e  (CDF)
- e+e+track (CDF + DØ)
- e++track (DØ)
- ++track (DØ)
- e+had+track (DØ)
- +had+track (DØ)
- Surpassed LEP sensitivity!
- Note: for tan>8 3-lepton                                 signatures are mostly 3-tau

- Expect large improvements from taus for high tan 

- SEASAPS-2005: New Results from Tevatron

## Rare Bs decays

- Rare Bs decays

- Decays that go through loops are very sensitive to new particles running in them

- M0 [GeV]

- current limit: 210-7

- CDF+DØ, 8fb-1: 210-8

- hep-ex/050836

- hep-ph/0108037

- will be able to observe signal and study asymmetries

- SEASAPS-2005: New Results from Tevatron

## Summary

-  Run II of the Tevatron is in its peak
-  _energy frontier;_ the only place for top and Bs
-  have ~10 times data than in Run I on tape
-  detectors are understood (almost) + some upgrades planned
-  no discoveries yet...
-  a lot of restrictive upper limits on new physics
-  **more data is coming!**
-  keep running till LHC starts churning out papers

- SEASAPS-2005: New Results from Tevatron