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Madrid, April 27, 2009 Aram Kotzinian 1 Longitudinal target polarization dependence of Λ polarization and polarized strangeness PDF Λ polarization Unpolarized target Strangeness distribution in nucleon Polarized target Polarized strangeness in polarized nucleon Conclusions Aram Kotzinian CEA-Saclay, IRFU/Service de Physique Nucléaire, 91191 Gif-sur-Yvette, France On leave in absence from YerPhI, Armenia and JINR, Russia DIS 2009, 26-30 April 2009, Madrid

1 Madrid, April 27, 2009 Aram Kotzinian Longitudinal target polarization dependence of polarization and polarized strangeness PDF polarization Unpolarized

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3 Madrid, April 27, 2009 Aram Kotzinian Intrinsic Strangeness Model (ISM) for Λ polarization P u (ud) 0 s s - Λ μ μ′μ′ R qq

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Page 1: 1 Madrid, April 27, 2009 Aram Kotzinian Longitudinal target polarization dependence of  polarization and polarized strangeness PDF  polarization Unpolarized

Madrid, April 27, 2009 Aram Kotzinian 1

Longitudinal target polarization dependence of Λ polarization and polarized strangeness PDF

Λ polarizationUnpolarized target

Strangeness distribution in nucleon

Polarized targetPolarized strangeness in polarized nucleon

Conclusions

Aram KotzinianCEA-Saclay, IRFU/Service de Physique Nucléaire, 91191 Gif-sur-Yvette, France

On leave in absence from YerPhI, Armenia and JINR, Russia

DIS 2009, 26-30 April 2009, Madrid

Page 2: 1 Madrid, April 27, 2009 Aram Kotzinian Longitudinal target polarization dependence of  polarization and polarized strangeness PDF  polarization Unpolarized

Madrid, April 27, 2009 Aram Kotzinian 2

Simple model: LO, independent fragmentationfor current fragmentation region

0TP

2

,0 2

( ) ( )( )

( ) ( )B

q qq

P Bq q

q

e q x D zP P D y P

e q x D z

2

(6) Model for spin transfer in fragmentation:

only ( )

( ) ( )1 ( ) ( )9 : ( , )

( ) ( ) ( )

0,

s s

s

q

s

x sB q q

D z D z

s x D zPS F x zD y P e q

SU

D z

x D z

Fraction of events with hard scattering off s-bar

(s-bar purity)

Page 3: 1 Madrid, April 27, 2009 Aram Kotzinian Longitudinal target polarization dependence of  polarization and polarized strangeness PDF  polarization Unpolarized

Madrid, April 27, 2009 Aram Kotzinian 3

Intrinsic Strangeness Model (ISM) for Λ polarization

P

u

(ud)0

ss-

Λ

μ

μ′

Rqq<Rq: spin transfer from intrinsic

strangeness and polarized diquark via heavier hyperons

P

u

(ud)0

Λ

μ

μ′

Rq<Rqq: spin transfer only

from final quark

J.Ellis,M.Karliner,D.Kharzeev,M.G.Sapozhnikov, 1995J.Ellis, D.Kharzeev, A.K., 1996

J. Ellis, A. K. & D. Naumov, 2002

TFR

CFR

Page 4: 1 Madrid, April 27, 2009 Aram Kotzinian Longitudinal target polarization dependence of  polarization and polarized strangeness PDF  polarization Unpolarized

Madrid, April 27, 2009 Aram Kotzinian 4

Spin transfer in SIDIS

Spin transferfrom qq side

Spin transferfrom q side

Page 5: 1 Madrid, April 27, 2009 Aram Kotzinian Longitudinal target polarization dependence of  polarization and polarized strangeness PDF  polarization Unpolarized

Madrid, April 27, 2009 Aram Kotzinian 5

NOMAD data

Page 6: 1 Madrid, April 27, 2009 Aram Kotzinian Longitudinal target polarization dependence of  polarization and polarized strangeness PDF  polarization Unpolarized

Madrid, April 27, 2009 Aram Kotzinian 6

Λ polarization

P

u

ss-μ

μ′

Rqq<Rq: spin transfer only

from intrinsic strangeness

Λ P

u

(ud)0

Λ

μ

μ′

Rq<Rqq: spin transfer only

from final quark

J.Ellis, A.K., D.Naumov and M.Sapozhnikov

EPJ.C52:283-294,2007

Page 7: 1 Madrid, April 27, 2009 Aram Kotzinian Longitudinal target polarization dependence of  polarization and polarized strangeness PDF  polarization Unpolarized

Madrid, April 27, 2009 Aram Kotzinian 7

NOMAD tuning usedBest description with SU(6)

model for spin transfer. polarization = s(x) filter

Unpolarized target

LEPTO MCs-bar purity

SU(6), CTEQ5L

Page 8: 1 Madrid, April 27, 2009 Aram Kotzinian Longitudinal target polarization dependence of  polarization and polarized strangeness PDF  polarization Unpolarized

Madrid, April 27, 2009 Aram Kotzinian 8

Quark type fraction in anti-Lambda production

( ) 0.15 0.2for x 0.1

sF x

LEPTO MC with CTEQ5L

and COMPASS cuts

In contrast to K production asymmetry,

here mainly s-bar contributes to

and P P

ud s

s

s

s

s

su

u

u

u

u

d

d

dd

d

Page 9: 1 Madrid, April 27, 2009 Aram Kotzinian Longitudinal target polarization dependence of  polarization and polarized strangeness PDF  polarization Unpolarized

Madrid, April 27, 2009 Aram Kotzinian 9

PDFs

2 22.5 (GeV/c)Q

Page 10: 1 Madrid, April 27, 2009 Aram Kotzinian Longitudinal target polarization dependence of  polarization and polarized strangeness PDF  polarization Unpolarized

Madrid, April 27, 2009 Aram Kotzinian 10

Hyperon production x-section and polarizationfor polarized beam and target

,

,

1

1

B

B

T

T

P B T

B B T TP

T

P

P

B

P P

P S P SPP P

Target polarization sign is written explicitlyBeam polarization contains sign

From general considerations for double and triple longitudinal polarization observables:

Triple-spin effect

Page 11: 1 Madrid, April 27, 2009 Aram Kotzinian Longitudinal target polarization dependence of  polarization and polarized strangeness PDF  polarization Unpolarized

Madrid, April 27, 2009 Aram Kotzinian 11

Polarization Asymmetry ( )P

A x

, ,

, ,

1:2:

B B

B

T

T B

T

T

P PP P

P PP P

P P P

P P P

( )( ) :( )P

P xA xP x

Polarization asymmetry

Page 12: 1 Madrid, April 27, 2009 Aram Kotzinian Longitudinal target polarization dependence of  polarization and polarized strangeness PDF  polarization Unpolarized

Madrid, April 27, 2009 Aram Kotzinian 12

Factorized LO QCD parton model2

,2

( )( ) ( ) ( )( )

( )1 ( ) ( ) ( )( )

B T

q B T qq

P P

q B T qq

q xe D y P fP q x D zq x

Pq xe D y P fP q x D z

q x

0.2 Deuteron0.14 Proton

effT T

forP fP

for

( )( ) 0.5 0.85, 0.5( )

( )( ) 0.85 0.8 0.2 0.5 0.068( )B T

q xD yq x

q xD y P fPq x

We can neglect

pol.dep. part in denom.

ISM expression is more complicated, but results are almost unchanged

Page 13: 1 Madrid, April 27, 2009 Aram Kotzinian Longitudinal target polarization dependence of  polarization and polarized strangeness PDF  polarization Unpolarized

Madrid, April 27, 2009 Aram Kotzinian 13

2 2

( ) ( )( ) ( ) ( )( ) 2

1 1( ) ( ) ( ) ( )( )9 9( ) , 2( )( ) ( ) ( ) ( )

( )1, for COMP

( )( )

2

ASS Deuteron target

( )(

( )

)

2

s s

B Tq q q q

B BP

T

q q

T

T

P

B

D y P D y Ps x P x A xs x fP fPP

s x D z s x D zs xP D y P P fPs xe q x D z e q x D z

D

P xA

y P

x COMPASSP x

x

fP

( )( )s x

s x

in LO QCD parton SU(6) model ( )P

A x

Page 14: 1 Madrid, April 27, 2009 Aram Kotzinian Longitudinal target polarization dependence of  polarization and polarized strangeness PDF  polarization Unpolarized

Madrid, April 27, 2009 Aram Kotzinian 14

ISM calculations using LEPTO

,

2

( )

2

( )

2

( , ,...) ( , ,...)( , ,...)

( , ,...)

( )( , ,...) ( ) ( ) ( )( )

( )( , ,...) ( ) ( ) ( )( )

( , ,...)

B T

q qq

q qq

q F qq FP P F

F

q F q B T q qq R R

qq F q B T q sqq R R

F q

N x x N x xP x x

N x x

q xN x x e D y P fP q x D z Sq x

q xN x x e D y P fP q x D z cq x

N x x e

( )1 ( ) ( ) ( )( )B T q

q

q xD y P fP q x D zq x

Separately calculate numerator and denominator by reweighting each generated event

Nomad settings and sq sqc cSymbolic notations: Lund Model is realization of Fracture Functions.

Spin transfer via heavy hyperons is taken into account.

Page 15: 1 Madrid, April 27, 2009 Aram Kotzinian Longitudinal target polarization dependence of  polarization and polarized strangeness PDF  polarization Unpolarized

Madrid, April 27, 2009 Aram Kotzinian 15

Two inputs for Pq=Δq/q

DSSV+MRST022008

GRSV+GRV2000sP

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Madrid, April 27, 2009 Aram Kotzinian 16

COMPASS cuts

Q2 > 1 (GeV/c)2; 0.2 < y <0.9Primary vertex: -100 < z < 100 or -30 < z < 30 (cm)

Decay vertex: 35 < zdec < 140 (cm)

Vertexes colinearity cut: θcol = 0.01

Decay particles momentum: p > 1 GeV/c

Feynman variable: 0.05 < xF < 0.5

Λ rest frame decay angle cut: cos(θ*) < 0.6

Page 17: 1 Madrid, April 27, 2009 Aram Kotzinian Longitudinal target polarization dependence of  polarization and polarized strangeness PDF  polarization Unpolarized

Madrid, April 27, 2009 Aram Kotzinian 17

Dependence on pol. PDFs

To verify sign change of Δsmeasure in two bins of x: x < 0.03 and 0.03 <x

Page 18: 1 Madrid, April 27, 2009 Aram Kotzinian Longitudinal target polarization dependence of  polarization and polarized strangeness PDF  polarization Unpolarized

Madrid, April 27, 2009 Aram Kotzinian 18

COMPASS preliminary

TP

TP

Sing change of ΔP corresponds to DSSV PDFs

Page 19: 1 Madrid, April 27, 2009 Aram Kotzinian Longitudinal target polarization dependence of  polarization and polarized strangeness PDF  polarization Unpolarized

Madrid, April 27, 2009 Aram Kotzinian 19

Conclusions(Anti)Lambda polarization measurements in SIDIS of polarized leptons off unpolarized and polarized targets can shed light unpolarized and polarized s-bar distributions in nucleon

(Anti)Lambda polarization on unpolarized target strongly depends on strangeness PDFPolarization asymmetry strongly depends on strangeness polarization shape

(Anti)Lambda polarization in SIDIS is well suited filter for nucleon strangeness study