Laurent Locatelli

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b bbar asymmetry analysis in q qbar -gt Z0 -gt
b bbar and production cross-sections with Pythia
6.325 analysis
Laurent Locatelli Laurent.Locatelli_at_epfl.ch LHCb
CERN Jets Working Group 26th January 2006
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b bbar asymmetry analysis in q qbar -gt Z0 -gt
b bbar
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Interaction Lagrangian between quarks and Z0
b
bbar
t
Z0
qbar
q
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Probability that the Z0 spin is in the same
direction than the parent and/or children quark
(for down and up quarks).
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Probability that the b quark coming from the Z0
is emitted forward knowing that the Z0 parent
quark is emitted forward (for d and u flavours).
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Z0 production analysis Proportion of Z0 parent
quark emitted forward and backward per flavour
type.
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Probability that the Z0 spin is emitted forward
and backward for down and up flavour types Z0
parent quarks.
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Probability that the b quark coming from the Z0
is emitted forward and backward for down and up
flavour types Z0 parent quarks.
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(No Transcript)
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Production cross-sections with Pythia 6.325
analysis
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LHCb standard Pythia settings
Selected sub-processes MSEL 0 MSUB(11) 1
f f' -gt f f'
(QCD) MSUB(12) 1 f fbar
-gt f' fbar' MSUB(13) 1 f
fbar -gt g g MSUB(28) 1
f g -gt f g MSUB(53) 1
g g -gt f fbar MSUB(68) 1
g g -gt g g MSUB(86) 1
g g -gt J/Psi g MSUB(87) 1
g g -gt Chi0c g MSUB(88) 1
g g -gt Chi1c g MSUB(89) 1
g g -gt Chi2c g MSUB(91) 1
Elastic scattering MSUB(92)
1 Single diffraction
(XB) MSUB(93) 1 Single
diffraction (AX) MSUB(94) 1
Double diffraction MSUB(95) 1
Low-pT scattering MSUB(106) 1
g g -gt J/Psi gamma MSUB(107) 1
g gamma -gt J/Psi g MSUB(108) 1
gamma gamma -gt J/Psi gamma
MSTP(2) 2 2nd order
calculation of alpha_s at hard interaction MSTP(33
) 3 alpha_s(Q2) -gt
alpha_s(KQ2) where K is PARP(33) MSTP(51)
19170 CTEQ4L in LHAPDF library (4032
in PDFLIB) MSTP(52) 2 Use
external LHAPDF library MSTP(82) 3
Turning off multiple interactions MSTP(128)
2 PARP(67) 1.0 Pythia default
value PARP(82) 3.47 PARP(85) 0.33
Pythia default value PARP(86) 0.66
Pythia default value PARP(89) 14000.0 PARP(90)
0.174 PARP(91) 1.0 Pythia
default value PARJ(13) 0.750 PARJ(14)
0.162 PARJ(15) 0.018 PARJ(16) 0.054 PARJ(17)
0.090
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Absolute cross sections
generated
sigma mb
tried
11 f f' -gt f f' (QCD) 124939 0
1.286D01 12 f fbar -gt f' fbar' 89
0 9.162D-03 13 f fbar -gt g
g 93 0 9.574D-03 28 f g -gt f
g 110695 0 1.140D01 53 g g
-gt f fbar 7118
0 7.328D-01 68 g g -gt g g 288547
0 2.970D01 86 g g -gt J/Psi g 570
2286 5.668D-02 87 g g -gt chi_0c
g 4838 31843 5.003D-01 88 g g
-gt chi_1c g 1229
14175 1.256D-01 89 g g -gt chi_2c g 5259
36701 5.336D-01 91 Elastic
scattering 216250 216250 2.221D01 92
Single diffractive (XB) 70115
70115 7.151D00 93 Single diffractive
(AX) 69129 69129 7.151D00 94 Double
diffractive 101114 102080 1.019D01 95
Low-pT scattering 0
544047 0.000D00 106 g g -gt J/Psi
gamma 15 38 1.343D-03 Total
100000 116145921 1.026D02
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V. Vagnoni's absolute cross sections
sigma mb
11 f f -gt f f (QCD) 12.37 12 f fbar -gt
f fbar 0.0092 13 f fbar -gt g
g 0.0080 28 f g -gt f g 11.20 53 g g
-gt f fbar 0.75 68 g g -gt g g 30.39 86
g g -gt J/Psi g 0.066 87 g g -gt chi_0c
g 0.61 88 g g -gt chi_1c g 0.15 89 g g
-gt chi_2c g 0.66 91 Elastic
scattering 22.21 92 Single diffractive
(XB) 7.151 93 Single diffractive (AX) 7.151
94 Double diffractive 10.2 106 g g -gt J/Psi
gamma 0.00096 TOT 102.9