27.2.2006 Novosibirsk

Standard Model and alpha

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Tests of the Standard Modeland (mZ)

Bolek Pietrzyk

LAPP, Annecy, IN2P3, CNRS

International Workshopee collisions from to

February 27 – March 2 2006, Novosibirsk, Russia

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Standard Model and alpha

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Precision measurements at Z pole

Precision of ISR corrections ~10-4

Precision of measurements ~10-3

Natural size of genuine Electroweak corrections is

effective couplings

%1~θπsin

)α(m2

2Z

(hep-ex/0509008) Phys. Reports acc.

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Standard Model and alpha

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Precise Electroweak Measurement

3

lepteff

2 θsin

lepteff

2 θsin

lepteff

2 θsin

all measurements are created equal but and mt are more equal than others George Orwell, Animal Farm

27.2.2006 Novosibirsk

Standard Model and alpha

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….. depend on , and …

Electroweak Radiative Corrections

2tm 2

W

2H

m

mln

Summer 2005

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Standard Model and alpha

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(s)Δα(s)Δα(s)Δα1

α(0)α(s)

t(5)hadl

ds's)(s's'

)(s'R

3π

αsReΠ

2π4m

hadγγ

P

)α(m2Z

00035.002758.0)(mΔα 2Z

(5)had

Phys. Rev. D72:057501, 2005

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)α(m2Z

from SM fits

114 GeV

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Predicting mt and finding top

SM fits, winter 1994

B. Pietrzyk, proceedings Moriond EW 1994

GeV177m 1811-19--11-t

Predicting mH and … searching for it

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Standard Model and alpha

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GeV 219 GeV,96m 6038-H

GeV 260 GeV,114m 6945-H

GeV 186 GeV,91m 4532-H

95% CL upper limit

174.3±-5.1

2003

(mt )

2005

172.7±2.9

(mt)

178.0±4.3

2004

(mt)

Recent changes in blue band plotprogress in mt measurement

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Standard Model and alpha

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CMD2 and KLOE measurements very minor change

- history … since 1989

Crystal Ball

BES

)α(m2Z

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- CMD2, KLOE and SND results – very minor change

CMD2 and KLOE points integrated separately, results of integration combined,

Adding SND results changes(mZ) by less than 1/10

R

R/R

(CM

D2

para

met

risat

ion

used

in o

ur 2

001

pap

er)

Previous measurements in the region were already relatively precise

)α(m2Z

2

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Standard Model and alpha

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– possible improvements

now 15% unct. in 1.05-2 GeV region5% unct. – total (mZ) unct. 0.00035 0.00027The change in the Higgs mass is small,but if the central value in 1-2 GeV region changes by +- 1, the central value of the Higgs mass changes by -9+16 GeVmore precise measurements are important.

)α(m2Z

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Precise EW measurements at the Z pole are now published (hep-ex/0509008).

Summary and conclusions

GeV is186limit upper CL %95 GeV,91m 4532-H

mH varies with and mt

Two important changes in the history of (mZ2) : Crystal Ball and BES results

Very minor change introduced by CMD2, KLOE and SND results-previous measurements in the region were already relatively precise

Looking forward to see also BABAR results.

New R measurements in the low cms energy region (particularly 1-2 GeV) will be important.

LHC will start at 2007 –Will the prediction from the SM fits for mH be as successful as it was for mt?

)α(m2Z