Collins fragmentation in Kaon prodution

Francesca Giordano

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Kinematics

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Francesca Giordano

Why do the ordering of couples differ in phi0 and phi1+phi2?

�12 /X

q,q

H?1,q(z1)H

?1,q(z2) cos(�1 + �2)

�0 /X

q,q

cos(2�0)F [(2h · kT1h · kT2 � kT1 · kT2)

H?1,q(z1)H

?1,q(z2)]

F [X] =X

qq

Zd2kT1d

2kT2 �2(kT1 + kT2 � qT)X

phi1+phi2 cross-section:

phi0 cross-section:

Different transverse momentum convolutions in the cross sections!

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Why do the ordering of couples differ in phi0 and phi1+phi2?

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phi0phi12 z1

z2

pt0

qTqT

pt1

pt2

z1

z2

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phi0phi12

0.49 0.42

Re-running asymmetries cutting at 0.5: are the phi0 and phi12 more similar?

z1

z2

z1

z2

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Linear fit

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phi12

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Average kinematics phi12z1

z2

pt1

pt2

qT

Small differences..

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phi0

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Average kinematics phi0

phi0 method

z2

pt0

qT

z1

Small differences..

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Jets versus Thrust

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Data with jets, R=1, energy>=2.75GeV

qT

Phi0 pipi pik

kkThrustJets

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Data with jets, R=1, energy>=2.75GeV

qT

Phi0

jet-selected hadron sample

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pipi

z1

z2

pt0

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qT qT

pik

z1

z2

pt0

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qT qT

kk

z1

z2

pt0

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qT qT

Data with jets, R=1, energy>=2.75GeV

qT

Phi12

ThrustJets

pipi pik

kk

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Data with jets, R=1, energy>=2.75GeV

qT

Phi12

jet-selected hadron sample

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T distribution

jet-selected hadron sample

Thrust-selected hadron sample

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pipi z1

z2

pt1

pt2

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qT

qT

pik z1

z2

pt2

pt1

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qT

qT

kk z1

z2

pt2

pt1

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qT

qT

Backup

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phi0 vs phi12

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Francesca Giordano

phi1+phi2 asymmetriespion-pion => non-zero

asymmetries, increase with z1,z2

pion-kaon => asymmetries compatible with zero

kaon-kaon => non-zero asymmetries, increase with z1,z2

smaller in size wrt pion-pion

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Francesca Giordano

phi0 asymmetries

pion-pion => non-zero asymmetries, increase with z1,z2

pion-kaon => asymmetries compatible with zero

kaon-kaon => non-zero asymmetries, increase with z1,z2

similar size of pion-pion

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Francesca Giordano

phi1+phi2 asymmetriesIndeed the pT dependence of the asymmetries is different between pions and kaons

phi1+phi2 asymmetries

These results can help extracting information on the different pT of pions and kaons!

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