1New QCD Tests with old JADE Data Stefan Kluth XXXXth Moriond QCD (2005)
New QCD Tests
with old JADE data
Stefan KluthMaxPlanckInstitut für PhysikFöhringer Ring 680805 München, [email protected]
XXXXth Recontres de Moriond (QCD), 1219 March 2005
2New QCD Tests with old JADE Data Stefan Kluth XXXXth Moriond QCD (2005)
e+e Annihilation in JADE
3New QCD Tests with old JADE Data Stefan Kluth XXXXth Moriond QCD (2005)
The JADE Experiment1979 to 1986 at PETRA/DESY↳ wwwjade.mppmu.mpg.de
4New QCD Tests with old JADE Data Stefan Kluth XXXXth Moriond QCD (2005)
JADE Data and Software
JADE code:simulationreconstructionevent display
√s selected events14 172222 138335 3486038 158444 3896
5New QCD Tests with old JADE Data Stefan Kluth XXXXth Moriond QCD (2005)
4Jet Rate (Durham)
Distance in phase space ~kt:
yij = 2 min(E
i2, E
j2)/E
vis2(1cosθ
ij)
combine particles with smallest y
ij by adding
4vectors
stop when yij > y
cut, count jets
Corrected data vs. models
[JADE note 146]
6New QCD Tests with old JADE Data Stefan Kluth XXXXth Moriond QCD (2005)
4Jet Rate FitsTheory is NLO (O(α
S2) + O(α
S3) radiative corrections) combined
with resummed NLLA
Hadronisation correction
αS(35 GeV) = 0.141 ± 0.001(stat.) ± 0.002(exp.)
± 0.003(had.) ± 0.001(theo.)Fit
[JAD
E note 146]
7New QCD Tests with old JADE Data Stefan Kluth XXXXth Moriond QCD (2005)
αS from FourJet Rate: Summary
Combine results from22 to 43.8 GeV:
αS(M
Z) = 0.1169
± 0.0004(stat.)± 0.0012(exp.)± 0.0021(had.)± 0.0007(theo.)
[JADE note 146]
8New QCD Tests with old JADE Data Stefan Kluth XXXXth Moriond QCD (2005)
αS from R
4: theory error
Theory error from RSvariation
0.5 < xµ = µ/Q < 2.0
depends on fit range
xµ = 1 close to PMS scale
⇒ RS variation resultsin small α
S variation
[hepph/9806317]
9New QCD Tests with old JADE Data Stefan Kluth XXXXth Moriond QCD (2005)
Moments ofEvent Shapes
Observables:
1T, MH, C, B
T, B
W, y
23(D)
⟨yn⟩ = ∫ yn 1/σdσ/dy dy'n = 1, ..., 5
Theory is NLO QCD:
⟨yn⟩ = Anα
S /(2π) + B
n(α
S /(2π))2
Complete phase space probed[JADE note 147]
10New QCD Tests with old JADE Data Stefan Kluth XXXXth Moriond QCD (2005)
Moments HadronisationHadronisation Correction 14 GeV
NLO/LO Ratio
[JADE note 147]
11New QCD Tests with old JADE Data Stefan Kluth XXXXth Moriond QCD (2005)
Moments ResultsFit α
S(M
Z) with x
µ = 1
1T, C, BT (n>1) unstable
⇒ require KαS /(2π) < 0.5
αS(M
Z) = 0.1286
± 0.0007(stat.)± 0.0011(exp.)± 0.0022(had.)± 0.0068(theo.)
Consistent with NLO xµ=1
fits to distributions[JADE note 147]
12New QCD Tests with old JADE Data Stefan Kluth XXXXth Moriond QCD (2005)
Summary● JADE data still alive and useful● Measure 4jet rate with Durham scheme
– NLO + NLLA QCD calculation
– precision measurement of αS from JADE
– αS(M
Z) = 0.1169 ± 0.0026 (preliminary)
● Study 1st 5 moments of event shapes– Theory always samples complete phase space
– Result for αS consistent for some but not all
observables