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Fragmentation fractions of heavy quarks
Leonid Gladilin (Moscow State University)

XXII International Workshop on HEP and QFT QFTHEP 2015, 24.06-01.07 2015, Samara
Outline : Introduction f(cHc) and f(bHc) at LEP
Eur. Phys. J. C75 (2015) 19 arXiv:1404.388

Hints for non-universality of fragm. Fractions

Summary


Fragmentation Functions and Fragmentation Fractions

Fragmentation Functions are strongly model dependent

Fragmentation Fractions are less model dependent, often assumed to be universal

f(cD), f(bB), f(bD) = f(bB)*BR(BD)
needed for normalisation of pQCD predictions
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Fragmentation fractions of c and b quarks into charmed hadrons at LEP
Eur. Phys. J. C75 (2015) 19 arXiv:1404.388

[6] PDG 2014. [7] Belle (2014) : B(c+ pK-+) = 6.84 ± 0.24 +0.21-0.27 % [8] CLEO (2000) : B(c+ pK-+) = 5.0 ± 0.5 ± 1.2 % In PDG 2014, B(c+ pK-+) = 5.0 ± 1.3 % (indirect, with large uncertainty due to model dependence

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LEP measurements of charm fragmentation fractions
ALEPH, DELPHI and OPAL rate measurements:

( ALEPH rate measurement)
Rc = 0.1723 (SM calculation) DELPHI and OPAL double-tag measurements:

( DELPHI double-tag measurement) ( OPAL double-tag measurement) Correct all results with latest branching fractions
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Charm fragmentation fractions
All LEP results:

Experiments are in fair agreement

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LEP measurements of bottom fragmentation fractions
ALEPH, DELPHI and OPAL rate measurements:

Rb = 0.21579 (SM calculation)

OPAL double-tag measurement:

( OPAL double-tag measurement) Correct all results with latest branching fractions
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Bottom fragmentation fractions
All LEP results:

Experiments are in fair agreement

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LEP fragmentation fractions
Weighted mean taking correlations into account:

Eur. Phys. J. C75 (2015) 19 arXiv:1404.388

1st uncert. - stat.&syst., 2nd uncert. - branching fractions f(cD0) + f(cD+) + f(cDs+) +f(cc+) = f(bD0) + f(bD+) + f(bDs+) +f(bc+) = Too low?

Important to measure fragmentation fractions to c+, c0 and c0.
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Hints for non-universality of fragmentation fractions
In previous averaging of f(cHc) (arXiv:hep-ex/9912064), LEP and B-fabric measurements were combined It is not done in the new averaging, because f(bHc) are certainly different at LEP and at s ~ 10 GeV f(cHc) show hints of non-universality as well: At LEP, f(cD*+) > f(cD+) At 10 GeV, f(cD*+) < f(cD+) Belle

Due to, in particular, exclusive production channels, e.g.:

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Hints for non-universality of fragmentation fractions
f(bb) demonstrates pT dependance at low pT: LHCb, arXiv:1111.2357 (for pT < 14 GeV):

Important to measure f(bb) in central LHC range (ATLAS, CMS)

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Summary
Averaging of LEP f(cHc) and f(bHc) measurements performed They are intended for normalisation of MC and analytical predictions

w.d. f(cHc) and w.d. f(bHc) look somewhat too low Important to measure fragmentation fractions to c+, c0 and There are hints for non-universality of fragmentation fractions Important to measure f(bb) at ATLAS and CMS

0 c

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