Recent Results from Tevatron

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Recent Results from Tevatron

• Yuri Gershtein
• On behalf of CDF and DØ collaborations

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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

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Tevatron Status
Oct 2005
Peak Luminosity

• 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

1.61032 cm-2s-1
Dec 2001
Integrated Luminosity
1.4 fb-1
24 pb-1/week
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CDF Experiment
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DØ Experiment
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Standard Model
LEP EWWG Summer 2005

• Standard Model survived yet another year
• Questions Mass, Unification and Flavor
• EW fits favor light Higgs
• If Higgs is light SM breaks at lt100 TeV

hep-ph/9708416
Allowed
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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
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B physics

• Bs mixing
• (CP violation, X(3872), Bc, B, D,?b, masses,
  lifetimes, etc)

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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
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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

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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

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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

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Prospects for BS Mixing Observation
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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/?
  ??(ll-) (KK-)
• ? 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
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Electroweak Physics

• W, top mass and Higgs
• (anomalous coupling limits, top properties, etc)

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W Mass and Width

• W mass measurement is one of the single most
  important measurements for Tevatron to make
• its 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

hep-ex/0510077
electron channel only
?W2.010.14 GeV
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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
• leptonjets mode one of the ts 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)

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Top Mass Measurement

• 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

• Template method
• Generate MC for many points in top mass and
  determine which fits the data best
• Leptonjets channel

Mtop 173.5 3.9/-3.8 GeV
Main source of uncertainty Jet Energy
Scale Calibrated using jets from W in the
signal events
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Top Mass Prospects
20
New Top Mass World Average
hep-ex/0507091
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Indirect Higgs Constraints

• MH9145-32 GeV
• MHlt186 GeV _at_95CL

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Direct Higgs Searches

• Main production mechanisms gluon fusion and
  associated W/Z production
• Main decay modes bb,?? for low mass, WW for
  high mass

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Higgs Search Channels

• Associated production with W/Z

• W?l? h?bb lepton 2b MET
• Z??? h?bb 2b MET
• W?l? h?WW?l? l? 3 leptons MET

• Gluon fusion production

• h?bb is hopeless background too large
• h??? 2 taus
• h?WW?l? l? 2 leptons MET

• MSSM Higgs use enhanced b coupling

H

• h?bb 4 b
• h??? 2 taus 2 b in the works

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Higgs Searches Summary

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

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Higgs Discovery Prospects
From T. Junks FNAL WC
Its possible to be lucky or unlucky!
per experiment
per experiment
mH115 GeV assumed
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Beyond the Standard Model

• Supersymmetry
• (many other searches for Extra Dimensions, Z,
  W, LQ, excited quarks and leptons, etc)

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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) gt 195 GeV PRL 94, 041801 (2005)
• CDF m(?1) gt 167 GeV PRD 71, 031104(R) (2005)

arXivhep-ex/0504004
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JetsMissing 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

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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)
• ee?/e (CDF)
• ???/e (CDF)
• eetrack (CDF DØ)
• e?track (DØ)
• ??track (DØ)
• e?hadtrack (DØ)
• ??hadtrack (DØ)
• Surpassed LEP sensitivity!
• Note for tan?gt8 3-lepton
  signatures are mostly 3-tau

Expect large improvements from taus for high tan ?
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Rare Bs decays

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

hep-ex/050836
will be able to observe signal and study
asymmetries
M0 GeV
hep-ph/0108037
CDFDØ, 8fb-1 2?10-8
current limit 2?10-7
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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