11

Поляризация Ламбда гиперонов в эксперименте ГЕРМЕС

С. Л. Белостоцкий

Семинар ОФВЭ 24.04.2012

2

EMC (1988) experiment and spin crisis

Deep Inelastic Scattering (DIS) of polarized muons on polarized target 0.12 0.09 0.14 1 !!!

Jaffe sum rule based on SU(3) f.s.and assumption of unpolarizedstrange sea (Δs=0 )

1 1

2 2z q gS G J J

quarks gluons orbital motion

to datesum rule

EMC, SMC, SLAC, HERMES, COMPASS, RHIC

exp theo

exp theo

exp theo

exp theo evol

u u 0.842 0.008 0.004

d d 0.427 0.008 0.004

s s 0.085 0.008 0.013

0.330 0.025 0.011 0.028

Hermes result

( s s 0)

u u 2F 0.928 d d F D 0.34

3F D 0.586 0

2

.08

3

Δu Δd Δs

p(uud) 0.84 -0.43 -0.09n(udd) -0.43 0.84 -0.09

Λ0(uds) -0.16 -0.16 0.64

Σ+(uus) 0.84 -0.09 -0.43

Σ0(uds) 0.375 0.375 -0.43

Σ-(dds) -0.09 0.84 -0.43

Ξ0(uss) -0.43 -0.09 0.84

Ξ-(dss) -0.09 -0.43 0.84

Lattice-QCD Δu=Δd=-0.02 Δs= 0.68 (±0.04)

Λ and other hyperon spin structure ? ?

Naïve CQM ΔΣ=1 Δu=Δd= 0 Δs= 1

∆Σ=0.32 F=0.47 D=0.81

Jaffe assumption (Δsproton=0) ΔΣ=0.586 Δu=Δd= -0.073 Δs= 0.732

Burkard & Jaffe from EMC result

ΔΣ=0.12 Δu=Δd= -0.23 Δs= 0.58 (±0.04)

4

Xp

e'

e

q

q

h

ad

ron

iza

tio

n

Spin transfer to Λ in DIS and Λ spin structure

DIS variables

LL LL,2 2

ff

2

f

2

(x, z) at Q Q

( D(y) 0.7 Q 2.41(

D

G

(x, z) D (z)

eV) for HERMES )

f ff

f f f

LL,f

F (D (z)

z) F (z)F (z)

F (z) F (z) F (z)

* LL ' LL 'L ' BD DP P P D(y)

In one-photon exchange mechanism

In LO QCD

2 2

2

Q (k k ')

E E ' yE

EQx z

2M

Here partial spin transfer

Linked to Λ spin structure in a modeldependent way, e.g. R.L.Jaffe PRD 1996

Reciprocity relation Gribov Lipatov PLB 37 1971

h hf fF (z) q (x)

5

HERA self-polarized positron beam (HERA shutdown in 2007)

Sokolov-Ternov effecttransverse polarization

spin rotatorslongitudinal polarization

40 50beamP %

27.6eE GeV

66

limited acceptance for Λ () hyperon detection(forward spectrometer) mostly current fragmentation

region XF positive

for Λ () produced within HERMES acceptance

decay kinematics is such that proton (anti proton)

is always leading particle

Λ and detection in HERMES experiment

-1.0 -0.5 0.0 0.5 1.0101

102

103

xF

0 5 10 15 200

1

2

3

4

5 protons pions

x105

p, GeV/c

*F

max

px in proton c.m. frame

p

7

V2

V1,

V1,e

p

e

beam

Λ and events selection

main bgr is π+ π- and K π pairs production; bgr supression cuts:• Leading rejection using threshold Cherenkov det. (1996-1997)

or RICH (1998-2007)• Vertex separation.Distance between V1 and V2 vertices > 5 cm

8

Λ, and Ks invariant mass distributions

1.08 1.10 1.12 1.14 1.160

2

4

6

8

10

12

14

16

N = 76281

= 1.92 MeV = 0.85

M(p,), GeV

x103

1,08 1,10 1,12 1,14 1,160,0

0,5

1,0

1,5

2,0

2,5

N = 11187

= 1.85 MeV = 0.85

x103

M(,), GeV

0,44 0,48 0,52 0,560

2

4

6

8

10

12 NKs

= 99034

= 5.44 MeV = 0.91

M(+, - ), GeV

x103

9

Important. Due to periodic beam polarization reversal

final date sample is practically helicity balanced , i.e

B

P(t)L(t)dt

L(t)dtP 0

Beam polarization periodic reversal helps to exclude acceptance effect

This essentially simplifies DLL extraction from the data

10

N2

i k1

N

B i1

ik

2

i

2

B

1D y cos cos

N

1P D y cos

N

P (t)L(t)dtP

L(t)dt

A

B

k2Bx

Lki

ik,y,z

Bi x, y,

PD A

1z

MC simulation of spectrometer acceptance is not needed, acceptance correction does not affect measured asymmetries. DLi

components are extracted using experimental data sample only !!

average over experimental data sample

For beam helicity balance case BP 0

0 0p B i

i x,y,zp p p

p

Li

p

dN dNdin rest frame

N(1 P k ) (1 P cos )

d d d

0.642 0.013 0.642 0.013

D����������������������������

Spectrometer acceptance results in strong distortion of decay angular distribution,intensive MC acceptance simulation (COMPSS)

-1,0 -0,5 0,0 0,5 1,00,0

0,5

1,0

1,5

2,0

2,5

'cos pL

unpolarized/ acceptancepolarized /acceptance

unpolarized/ 4πpolarized / 4π

Extraction of DLi components from experimental data sample

111111

Coordinate systems in Λ rest frame

All 3 components of spin transfer are extracted from the data in Λ hyperon rest frame using two coordinate system:

I. X,Y,Z with Z along virtual photon momentum

X’,Y’,Z’ with Z’ along Λ momentum (in lab frame)

II. Z and Z’ are used to be Longitudinal spin transfer axes

X and X’ transverse spin transfer axes

XY 'Y

'X

'Z

p*p

p

Z productionplane

LiD

ImportantY and Y’ components of spin transfer are compatible with zero due to parity conservation requirement

t arg et

lab* t arg et

* P X,

in rest frame p and p p

12

-0,3

-0,2

-0,1

0,1

0,2

0,3

-0,3 -0,2 -0,1 0,1 0,2 0,3

DLx

DLz

z axis along p

-0.3

-0.2

-0.1

0.1

0.2

0.3

-0.3 -0.2 -0.1 0.1 0.2 0.3

DLx

DLz

z axis along p

Results: Integrated spin transfer for Λ

12

0 016 0 0042 0 02

0 0037 0 0037 0 02

0 186 0 040 0 02

0 187 0 040 0 02

Lx stat syst

Ly stat syst

Lz stat syst

LL ' stat syst

D . . .

D . . .

D . . .

D . . .

0 133 0 0039 0 02

0 0037 0 0037 0 02

0 147 0 038 0 02

0 197 0 039 0 02

Lx stat syst

Ly stat syst

Lz stat syst

LL ' stat syst

D . . .

D . . .

D . . .

D . . .

2 2FQ 2.14(GeV) , y 0.64, x 0.073, z 0.43, x 0.30

Spin is transferred along virtual photon momentum

1313

0,0 0,2 0,4 0,6-0,6

-0,4

-0,2

0,0

0,2

0,4

0,6

0,8

L' = Z

xF

Lo

ng

itu

din

al D

LL

'

0,04 0,08 0,12 0,16 0,20-0,6

-0,4

-0,2

0,0

0,2

0,4

0,6

0,8

L' = ZLongitudin

al D

LL'

x

0,4 0,5 0,6 0,7 0,8 0,9-0,6

-0,4

-0,2

0,0

0,2

0,4

0,6

0,8

L' = Z

Lo

ng

itu

din

al D

LL

'

y

0,2 0,3 0,4 0,5 0,6 0,7-0,6

-0,4

-0,2

0,0

0,2

0,4

0,6

0,8

L' = Z

Lo

ng

itu

din

al D

LL

'

z

Results: Dependences on kinematic variables for Λ hyperon

1414

0,04 0,08 0,12 0,16 0,20-0,6

-0,4

-0,2

0,0

0,2

0,4

0,6

0,8

hh Ks

x

D Lz

0,4 0,5 0,6 0,7 0,8 0,9-0,6

-0,4

-0,2

0,0

0,2

0,4

0,6

0,8 hh Ks

y

D Lz

-0,1 0,0 0,1 0,2 0,3 0,4 0,5 0,6-0,6

-0,4

-0,2

0,0

0,2

0,4

0,6

0,8 hh Ks

xF

D Lz

0,2 0,3 0,4 0,5 0,6 0,7-0,6

-0,4

-0,2

0,0

0,2

0,4

0,6

0,8 hh Ks

zD Lz

0.017 0.006

0.015 0.006

0.012 0.006

hhLx

hhLy

hhLz

D

D

D

0.019 0.030

0.015 0.031

-0.001 0.033

KsLx

KsLy

KsLz

D

D

D

False asymmetry control using h+h- and KS

15

LL ' LL ',f ff

D D

LL,f fD q

0.0 0.1 0.2 0.30.0

0.2

0.4

0.6

0.8

1.0

u d s

Pu

riti

es

x 0.08 0.16 0.24-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8 CQM Bu./Jaf SU(3) Lattice QCD

x

D L

L

15

Constituent quark model (CQM) u=d=0, s=1

Burkard/Jaffe u=d=-0.23, s=0.58

SU(3) flavor symmetry u=d=-0.09, s=0.47

Lattice QCD u=d=-0.02, s=0.68

Simple estimation of spin transfer to Λ

R.L. Jaffe PRD 54, (1996), C. Boros et al PRD 61, (2000),Ashery&Lipkin PLB 469 (1993), B.Q.Ma et al PLB 477

1616

-0,8 -0,4 0,0 0,4-1,5

-1,0

-0,5

0,0

0,5

HERMES (L' = Z) NOMAD (L' = Z)E665 (L' = Z')COMPASS (L' = Z)

xF

Lo

ng

itu

din

al D

LL

'

Longitudinal spin transfer to Λ world data

1717

-0,4 -0,2 0,0 0,2 0,4 0,6

-0,5

0,0

0,5

1,0

1,5HERMES (L' = X) NOMAD (L' = X)

xF

Tra

ns

ve

rse

D L

L'

-0,4 -0,2 0,0 0,2 0,4 0,6

-0,5

0,0

0,5

1,0

1,5HERMES (L' = Z) HERMES (L' = Z') NOMAD (L' = Z)E665 (L' = Z')COMPASS (L' = Z)

xF

Lo

ng

itu

din

al

D LL

'

Longitudinal and transverse spin transfer to world data

1818

Overview of Lambda physics at HERMES

DIS regime

•Spin transfer coefficient DLL from polarized beam in semi inclusive Λ and production •Multiplicity and fragmentation function u-quark to Λ Quasi real (inclusive) photoproduction

•Spin transfer coefficient KLL from polarized target to Λ or •Spin transfer coefficient DLL from polarized beam to Λ or •Transverse Λ and polarization, A-dependence of Λ polarization

2 2Q 0.8(GeV)

2Q 0

e and Λ () detected incoincidence

e not detected, Λ () detectedinclusively

3N 80 10

6N 0.5 10

Published:Measurement of longitudinal spin transfer to Lambda hyperons in deep inelastic lepton scattering.Phys.Rev.D64:112005,2001.Longitudinal Spin Transfer to the Lambda Hyperon in Semi-Inclusive Deep-Inelastic Scattering.Phys.Rev.D74:072004,2006.Transverse Polarization of Lambda and anti-Lambda Hyperons in Quasireal Photoproduction.Phys.Rev.D76:092008,2007.

PhD thesis 7

Conference proceedings about 25

To be published :Draft 88. Final paper on DLLDraft 83. A-dependens of transverseLambda polarization

1919

BACKUP SLIDES

20

Purity distributions within HERMES acceptance

'

'

2f ' f f

f f2ff . ff '

f '

e q (x)F (z)(x, z) 1

e q (x)F (z)

LL LL,f

L

ff

1

ff 0

L LL,f

D (x, z) D (z)

D (z) D (z)

(x, z)

(x, z)dx

Calculated using LUND MCPurity and partial spin transfer

2121

0 14 0 11 0 02

0 05 0 10 0 02

0 05 0 10 0 02

0 15 0 11 0 02

Lx stat syst

Ly stat syst

Lz stat syst

LL ' stat syst

D . . .

D . . .

D . . .

D . . .

-0.3

-0.2

-0.1

0.1

-0.1 0.1 0.2 0.3

DLx

DLz

z axis along p

-0,3

-0,2

-0,1

0,1

-0,1 0,1 0,2 0,3

DL

Lx

DL

Lz

z axis along pL

'

-0.07 0.10 0.02

0.05 0.10 0.02

0.13 0.09 0.02

0.15 0.10 0.02

Lx stat syst

Ly stat syst

Lz stat syst

LL stat syst

D

D

D

D

Results: Integrated spin transfer for

2 2FQ 1.98(GeV) , y 0.71, x 0.059, z 0.37, x 0.25

2222

0.0 0.2 0.4 0.6-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

hhK

S

D L

L'

xF

0.00 0.05 0.10 0.15 0.20-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

hhK

S

D L

L'

x

0.4 0.5 0.6 0.7 0.8 0.9-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

hhK

S

y

D L

L'

0.18 0.36 0.54-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

hhK

S

D L

L'

z

' 0.021 0.006hhLLD

' 0.023 0.054KsLLD

False asymmetry control using h+h- and KS

23

Multiplicity distribution and fragmentation function

Multiplicity z-distribution Fragmentation function u→Λ

* *

*

( ) ( )u dD z D z

E mz

Belostotski “Strangeness polarization…” Trento, Oct.2008

2( )( )

( ) ( ) ( , ) { } ( )( )

1 { } ( ) 1

qqq q q

q qe

q qq q

n zN zn z n z D z Q Pu z

N n z

Pu z

24

Hyperon Decay mode, %

Hyperonyield

AntihyperonYield

1116 p 63.9 386000 72000

1193 100 19000 5200

1321 99 2500 650

1393 88 5700 820

1388 88 6300 1200

Contribution to Parent particles Λ production (%)

String(direct) 40

18

and

4

38

Λ() from hyperon (anti-hyperon) decays (quasi-real photoproduction regime)

Belostotski “Strangeness polarization…” Trento, Oct.2008

25

-1.0 -0.5 0.0 0.5 1.0101

102

103

xF

XF distributions (semi-inclusive DIS)

Pythia MC for Λ Experiment for Λ and

HERMES is a forward spectrometer pΛ(min)~1 GeV

Belostotski “Strangeness polarization…” Trento, Oct.2008

26

Summary of HERMES data-taking with polarized targets

year type target polar. %

1995 3He 461996 H 76 1997 H 851998 D 861999 D 832000 D 84.5

1994 HERMES test RUN

1995-2000 HERMES RUN I

Beam pol. =51%

Lumi H,D pol=259 pb-1

Lumi unpol = 593 pb-1

(H,D, 3He, 4He, 14N, 20Ne and 84Kr)

2001-2002 HERA lumi upgrade

2002-2007 HERMES RUN II

Longitudinal polarization

Transverse polarizationyears type polar.%2002-2005 H 78

2006-2007 unpol (RD)Beam pol. =36%Lumi H pol=161 pb-1Lumi unpol ~ 530 pb-1 Belostotski “Strangeness polarization…” Trento, Oct.2008

2727

Angular distribution of decay protons in

Λ rest frame

-1,0 -0,5 0,0 0,5 1,00,0

0,5

1,0

1,5

2,0

2,5

'cos pL

Distorted by spectrometer acceptance

May in principle be calculated using MC

difficulty to avoid false asymmetry induced by MC

acceptance simulation

0LL ' pBeam

p p

dNdN(1 P D k )

d d

0.642 0.013

����������������������������

0

p

0pL '

p

for 4 acceptance

for restrict

dNconst

d

dN cos

d

ed acceptance

depends on

PB=DLL’=1PB=0

28

results15 6.e p X at E GeV

inclusively detected

nP

��������������

Lower ς (lower t) higher Λ polarization

Phys Rev. D 2007 (RUN I)

Belostotski “Strangeness polarization…” Trento, Oct.2008

29

Transverse Lambda polarization A/Z dependence

30

low mass spin 1/2(3/2) baryon 8-et (10-et) can be built using various combination of

u, d, s quarks within

SU(3)_flavor

symmetry model

●

●

●

●

●

●

Magnetic moments of baryons well described, e.g.

It implies that in nCQM

Naïve Constituent Quark Model nCQM

3131

Longitudinal Polarization of the Lambda in Deep Inelastic Scattering of Polarized Positrons from Nucleons G. Schnell Ph.D. Thesis, New Mexico State University, May 1999Messungen zum Spintransfer bei Lambda0-Produktion im polarisierter Lepton-Nukleon Streuung im HERMES-Experiment S. Bernreuther Dissertation, Friedrich-Alexander-Universitaet Erlangen-NuernbergInvestigation of Lambda-hyperon production in deep inelastic positron nucleon scattering in the HERMES experiment Y. Naryshkin Dissertation, Gatchina 2001Lambda Hyperon Production Mechanisms and Longitudinal Spin Transfer at HERMES H.C. Chiang Senior Thesis, University of Illinois at Urbana-Champaign, Sep 2002Measurement of the Transverse Spin Polarization of the Lambda in Quasi-Real Photoproduction and Electroproduction at HERMES PDF format A.E. Andrus Ph.D. thesis, University of Illinois at Urbana-Champaign, May 2006Quasi-real photo-production of hyperons and their impact on the Lambda polarization measurements PDF format A.J. Reischl PhD thesis University of Amsterdam, April 2007The polarization of Lambda hyperons in quasi-real photoproduction PDF format M. Demey PhD thesis University of Amsterdam, March 2007Hyperon production at the HERMES experiment PDF format C. Bonomo Ph.D. thesis, Universita' degli Studi di Catania, Feb 2007

PhD theses on lambda physics at HERMES

3232

14th International Conference on Particles and Nuclei (PANIC 96) May 22 - 28, 1996 .......... Williamsburg, USA S. Belostotski - hadron spectroscopyResults on Lambda0 Production at HERMES P. Chumney 2nd Topical Work on Deep Inelastic Scattering off Polarized Targets: Theory Meets Experiment (SPIN 97), Zeuthen, Germany, Sep 1 - 5, 1997 Lambda Production at HERMES P. Chumney 7th International Conference on Mesons and Light Nuclei, Pruhonice, Prague, Czech Republic, Aug 31 - Sep 4, 1998Study of Strange Particle Production in HERMES Experiment S.L. Belostotski 13th International Symposium on High Energy Spin Physics (SPIN 98), Protvino, Russia, Sep 8 - 12, 1998Strange Particle Production and Polarization of Lambda Hyperons in the HERMES Experiment S. Belostotski 7th International Work on Deep Inelastic Scattering and QCD (DIS 99), Zeuthen, Germany, Apr 19 - 23, 1999Lambda Polarization Measured at HERMES and Lambda Spin Structure S. Belostotski International Work on Symmetry and Spin (PRAHA-SPIN 99), Prague, Czech Republic, Sep 5 - 12, 1999Fragmentation Function of Up Quark to Lambda Measured in the HERMES Experiment S. Belostotski, O. Grebenyuk, Y. Naryshkin Workshop on the physics problems of Nucleon Structure and Meson Spectroscopy, Dubna, Russia, Oct 9 - 15, 2000Longitudinal Lambda Polarization Measured at HERMES O. Grebenyuk 9th International Work on Deep Inelastic Scattering and QCD (DIS 2001), Bologna, Italy, Apr 27 - May 1, 2001Longitudinal spin transfer to the Lambda hyperon in lepto-production S. Belostotski IX Workshop on High Energy Spin Physics, Dubna, Russia, Aug 2 - 7, 2001Transverse polarization of Lambda hyperons produced inclusively in eN-scattering at HERMES S. Belostotski and O. Grebenyuk IX Workshop on High Energy Spin Physics, Dubna, Russia, Aug 2 - 7, 2001Transverse Polarization of Lambda and Lambda-bar Produced Inclusively in eN Scattering at HERMES O. Grebenyuk 10th International Workshop on Deep Inelastic Scattering and QCD (DIS 2002), Cracow, Poland, Apr 30 - May 4, 2002Transverse Polarisation of Lambda and Lambda Hyperons in Quasi-Real Photon Nucleon A. Brüll 15th International Spin Physics Symposium (SPIN02), Brookhaven National Lab, NY, USA, Sep 9 - 14, 200210th International Workshop on Deep Inelastic Scattering and QCD (DIS 2002) Apr 30 - May 4, 2002 .......... Cracow, Poland Y. Naryshkin – Study of Lambda hyperon production and longitudinal spin transfer in the HERMES ExperimentMESON2004 Workshop Jun 4 - 8, 2004 .......... Krakow, Poland Y. Naryshkin - Hyperon production at HERMESHyperon Production at HERMES S. Belostotski 16th International Spin Physics Symposium (SPIN04), Trieste, Italy, Oct 10 - 16, 2004 INFO: Proc. of the 16th Int. Spin Physics Symposium (SPIN), Trieste/I (2005) World Scientific p.400Topical Aspects of Hyperon physics S. Belostotski ASI Summer School in Hadron Physics, St. Andrews, Scotland, UK, Aug 22 - Sep 29, 2004 INFO: Proc. of 58th Scottish Universities Summer School in Physics (SUSSP58): A NATO Advanced Study Institute and EU Hadron Physics 13 Summer Institute, St. Andrews, Scotland IOP PublishingMeasurement of longitudinal spin transfer to the Lambda0-hyperon at HERMES Yu. Naryshkin 7th International Conference on Hyperons, Charm and Beauty Hadrons (BEACH 2006), Lancaster University, Lancaster, United Kingdom, Jul 2 - 8, 2006 INFO: Nuclear Physics B 167 110-113Measurement of Transverse Lambda Polarization in Quasi-Real Photoproduction at HERMES Yu. Naryshkin 15th International Workshop on Deep Inelastic Scattering and QCD (DIS 2007), Munich, Germany, Apr 16 - 20, 2007 INFO: Proc. of 15th Int. Workshop on Deep-Inelastic Scattering and Related Subjects (DIS07), Sep. 2007. doi:10.3360/dis.2007.95Lambda and antiLambda polarization and spin transfer in photoproduction at HERMES format D. Veretennikov 12th Workshop on High Energy Spin Physics (DSPIN-07), Dubna, Russia, Sep 3 - 7, 2007 INFO: Proceedings of XII Advanced Research Workshop on High Energy Spin Physics (DSPIN-07), JINR(2008), p381SPIN TRANSFER COEFFICIENT KLL IN Lambda PHOTOPRODUCTION AT HERMES′ D. Veretennikov 16th International Workshop on Deep Inelastic Scattering and QCD (DIS 2008), London, UK, Apr 7 - 11, 2008 INFO: Proc. of XVI International Workshop on Deep-Inelastic Scattering and Related Subjects (DIS'08), Sept 2008. doi:10.3360/dis.2008.212Polarization Effects in Lambda and Anti-Lambda Production at Hermes *PDF format S.Belostotski 18th International Spin Physics Symposium (SPIN 2008), Charlottesville, VA, USA, Oct 6 - 11, 2008 INFO: To be published by AIPEuropean Nuclear Physics Conference (ENPC09) Mar 16 - 20, 2009 .......... Bochum, GermanyY. Naryshkin - A-dependence of lambda polarisationPhysics at HERMES *PDF format Yu. Naryshkin XIII Workshop on High Energy Spin Physics (DSPIN09), Dubna, Russia, Sep 1 - 5, 2009Lambda polarization at HERMES *PDF format Yu. Naryshkin BEACH'10: 9th International Conference On Hyperons, Charm And Beauty Hadrons, Perugia, Italy, Jun 21 - 26, 201019th International Spin Physics Symposium (SPIN 2010) Sep 27 - Oct 2, 2010 .......... Juelich, GermanyYuri N. - Transverse Lambda polarisation19th International Spin Physics Symposium (SPIN 2010) Sep 27 - Oct 2, 2010 .......... Juelich, Germany Denis V. - long. Lambda polarisation 20th International Spin Physics Symposium (SPIN 2010) April 2011, Newport news Virginia, USA S.Belostotski Spin transfer in DIS