LA FISICA DELLO SPIN CON ANTIPROTONI @ GSI

Caffè di Sezione INFN – Torino 05/07/2004

Mauro AnselminoMarco Maggiora

V. Abazov1, G. Alexeev1, M. Alexeev2, A. Amoroso2, N. Angelov1, M. Anselmino3, S. Baginyan1, F. Balestra2, V. A. Baranov1, Yu. Batusov1, I. Belolaptikov1, R. Bertini2, N. Bianchi11, A. Bianconi4, R. Birsa13, T. Blokhintseva1, A. Bonyushkina1, F. Bradamante13, A. Bressan13, M. P. Bussa2, V. Butenko1, M. Colantoni5, M. Corradini4, S. DallaTorre13, A. Demyanov1, O. Denisov2, E. De Sanctis11, P. DiNezza11, V. Drozdov1, J. Dupak9, G. Erusalimtsev1, L. Fava5, A. Ferrero2, L. Ferrero2, M. Finger6, M. Finger7, V. Frolov2, R. Garfagnini2, M. Giorgi13, O. Gorchakov1, A. Grasso2, V. Grebenyuk1, D. Hasch11, V. Ivanov1, A. Kalinin1, V. AKalinnikov1, Yu. Kharzheev1, N. V. Khomutov1, A. Kirilov1, E. Komissarov1, A. Kotzinian2, A. S. Korenchenko1, V. Kovalenko1, N. P. Kravchuk1, N. A. Kuchinski1, E. Lodi Rizzini4, V. Lyashenko1, V. Malyshev1, A. Maggiora2, M. Maggiora2, A. Martin13, Yu. Merekov1, A. S. Moiseenko1, V. Muccifora11, A. Olchevski1, V. Panyushkin1, D. Panzieri5, G. Piragino2, G. B. Pontecorvo1, A. Popov1, S. Porokhovoy1, V. Pryanichnikov1, M. Radici14, P. G. Ratcliffe12, M. P. Rekalo10, P. Rossi11, A. Rozhdestvensky1, N. Russakovich1, P. Schiavon13, O. Shevchenko1, A. Shishkin1, V. A. Sidorkin1, N. Skachkov1, M. Slunecka7, A. Srnka9, V. Tchalyshev1, F. Tessarotto13, E. Tomasi8, F. Tosello2, E. P. Velicheva1, L. Venturelli4, L. Vertogradov1, M. Virius9, G. Zosi2 and N. Zurlo4

ASSIA LOI

1Dzhelepov Laboratory of Nuclear Problems, JINR, Dubna, Russia2Dipartimento di Fisica ``A. Avogadro'' and INFN - Torino, Italy 3Dipartimento di Fisica Teorica and INFN - Torino, Italy 4Università and INFN, Brescia, Italy 5Universita' del Piemonte Orientale and INFN sez. di Torino - Italy6Czech Technical University , Prague, Czech Republic7Charles University, Prague, Czech Republic8DAPNIA,CEN Saclay, France9Inst. of Scientific Instruments Academy of Sciences,Brno, Czech Republic 10NSC Kharkov Physical Technical Institute, Kharkov, Ukraine 11Laboratori Nazionali Frascati, INFN, Italy12Università dell' Insubria,Como and INFN sez. Milano, Italy13University of Trieste and INFN Trieste, Italy14INFN sez. Pavia, Italy

Ma Bo-QiangDepartment of Physics, Beijing, P.R. China

Klaus Goeke, Andreas Metz, and Peter SchweitzerInstitut für Theoretische Physik II, Ruhr Universität Bochum, Germany

Jens Bisplinghoff, Paul-Dieter Eversheim, Frank Hinterberger, Ulf-G. Meißner, and Heiko RohdjeßHelmholtz-Institut für Strahlen- und Kernphysik, Bonn, Germany

Sergey Dymov, Natela Kadagidze, Vladimir Komarov, Anatoly Kulikov, Vladimir Kurbatov, Vladimir Leontiev, GogiMacharashvili, Sergey Merzliakov, Valerie Serdjuk, Sergey Trusov, Yuri Uzikov, Alexander Volkov, and Nikolai

ZhuravlevLaboratory of Nuclear Problems, Joint Institute for Nuclear Research, Dubna, Russia

Igor Savin, Vasily Krivokhizhin, Alexander Nagaytsev, Gennady Yarygin, Gleb Meshcheryakov, Binur Shaikhatdenov, Oleg Ivanov, Oleg Shevchenko, and Vladimir Peshekhonov

Laboratory of Particle Physics, Joint Institute for Nuclear Research, Dubna, Russia

Wolfgang Eyrich, Andro Kacharava, Bernhard Krauss, Albert Lehmann, David Reggiani, Klaus Rith, Ralf Seidel, Erhard Steffens, Friedrich Stinzing, Phil Tait, and Sergey Yaschenko

Physikalisches Institut, Universität Erlangen-Nürnberg, Germany

Guiseppe Ciullo, Marco Contalbrigo, Marco Capiluppi, Paola Ferretti-Dalpiaz, Alessandro Drago, Paolo Lenisa, Michelle Stancari, and Marco Statera

Instituto Nationale di Fisica Nucleare, Ferrara, Italy

Nicola Bianchi, Enzo De Sanctis, Pasquale Di Nezza, Delia Hasch, Valeria Muccifora, Karapet Oganessyan, and Patrizia Rossi

Instituto Nationale di Fisica Nucleare, Frascati, Italy

PAX LOI

Stanislav Belostotski, Oleg Grebenyuk, Kirill Grigoriev, Peter Kravtsov, Anton Izotov, Anton Jgoun, Sergey Manaenkov, Maxim Mikirtytchiants, Oleg Miklukho, Yuriy Naryshkin, Alexandre Vassiliev, and Andrey Zhdanov

Petersburg Nuclear Physics Institute, Gatchina, Russia

Dirk RyckboschDepartment of Subatomic and Radiation Physics, University of Gent, Belgium

David Chiladze, Ralf Engels, Olaf Felden, Johann Haidenbauer, Christoph Hanhart, Andreas Lehrach, Bernd Lorentz, Nikolai Nikolaev, Siegfried Krewald, Sig Martin, Dieter Prasuhn, Frank Rathmann, Hellmut Seyfarth, Alexander

Sibirtsev, and Hans StröherForschungszentrum Jülich, Institut für Kernphysik Jülich, Germany

Ashot Gasparyan, Vera Grishina, and Leonid KondratyukInstitute for Theoretical and Experimental Physics, Moscow, Russia

Alexandre Bagoulia, Evgeny Devitsin, Valentin Kozlov, Adel Terkulov, and Mikhail ZavertiaevLebedev Physical Institute, Moscow, Russia

N.I. Belikov, B.V. Chuyko, Yu.V. Kharlov, V.A. Korotkov, V.A. Medvedev, A.I. Mysnik, A.F. Prudkoglyad, P.A. Semenov, S.M. Troshin, and M.N. Ukhanov

High Energy Physics Institute, Protvino, Russia

Mikheil Nioradze, and Mirian TabidzeHigh Energy Physics Institute, Tbilisi State University, Tbilisi, Georgia

Mauro Anselmino, Vincenzo Barone, Mariaelena Boglione, and Alexei ProkudinDipartimento di Fisica Teorica, Universita di Torino and INFN, Torino, Italy

Norayr Akopov, R. Avagyan, A. Avetisyan, S. Taroian, G. Elbakyan, H. Marukyan, and Z. HakopovYerevan Physics Institute, Yerevan, Armenia

PAX LOI (continued)

Introduction

• SIS300 @ GSI:• HESR @ GSI:• ASSIA: from SIS300 to fixed target or HESR collider• PAX: HESR to fixed target

• A complete description of nucleonic structure requires:

@ leading twist and @ NLO

• Physics objectives:� Drell-Yan di-lepton production

� spin observables in hadron production

� electromagnetic form factors

� proton and gluon distribution functions

� quark fragmentation functions

( )fm104�GeV/c40,) p ( p 2pP −↑ ⋅=≥

GeV/c15 ,) p ( p Pp≤↑

) p ( p ↑ p↑

p↑

=

=

=

f1

h1T

g1L g1T =

f1T =

h1 =

h1T =h1L =

S = kx +k TTquark p

Pp P

f1, g1 studied for decades: h1 essentially unknown

)kx,(fkd)x(f T1T2

1 �=

Twist-2 PDFs

�T-dependent Parton Distributions

h1,

ULT

f1

g1

,

Chiralityeven odd

Twist-2

Distribution functions

h1

⊥

h1L

⊥

h1T

⊥f 1T

⊥ g1T

����������������������� ����� �����������������

Status from literature

Transversity h1 still unmeasured and poorly modeledA review in Barone, Drago, Ratcliffe, Phys. Rep. 359 (2002) 1

2

Why Drell Yan?Asymmetries depend on PD only (SIDIS�convolution with QFF)

Why ?Each valence quark can contribuite to the diagram

Kinematics

Drell-Yan Di-Lepton Production X��pp −+→

p

q2PM

x1

2

1 •=

xxx 21F−=

q2PM

x2

2

2 •=

sM

xx�2

21 ==

0QM 22 >=λλ

plenty of (single) spin effects3 planes: plane to polarisation vectors

planeplane

⊥*�p −

*�−+λλ

Scaling:

Full x1,x2 range .

needed

[1] Anassontzis et al., Phys. Rew. D38 (1988) 1377

Drell-Yan Di-Lepton Production X��pp −+→

[ ]� ++

=a 2

aa2

a1

a2a

212

2

F2

2

)(x(x1)ff)(x)f(xfexx

1s9M�4�

dxdMd

[ ]0,1�∈�

s1

dx�dd

F

2

∝

Gev/c 40pBEAM ≥ρ

[ ]1X��pp

nb 0.3 ≈−+→

Phase space for Drell-Yan processes

30 GeV/c

15 GeV/c

40 GeV/c

τ = const: hyperbolaexF = const: diagonal

PANDA

ASSIA

Uncorrelated quark helicities access chirally-odd functions

TRANSVERSITY

Drell-Yan Asymmetries — Polarised beam and target

�

Ideal because:

• h1 not to be unfolded with fragmentation functions

• chirally odd functionsnot suppressed (like in DIS)

Drell-Yan Asymmetries — Polarised beam and target

��

=a 2

a

11

a

1

2

a

a 2

a

11

a

1

2

a

LL)()(

)()(

xfxfexgxge

A��

+=

a 2

a

11

a

1

2

a

a 2

a

11

a

1

2

a2

2

TT )()(

)()(

cos1cos2�sin

xfxfexhxheA

�

� ����

�

+=

a 2

a

11

a

1

2

a

a 2

a

11

a

L2

a

T21

a

1

2

a

22LT )()(

)()(1-)()(

Q

Mcos1

cos� 2sin2

xfxfexhxhxxgxxge

A

To be corrected for:

NH3 polarised target:TB PfP

1

60.17173

f ==

0.85PT≈

RICH energies: small x1 and/or x2

evolution much slower[1] than �q(x,Q2) and q(x,Q2) at small x

ATT @ RICH very small, smaller would help[1]

Drell-Yan Asymmetries — Polarised beam and target

GeV 100s = 100M2 = -210� ≤

)Q(x,h 2a1

s

[1]Barone, Colarco and Drago, PRD56 (1997) 527.

220 GeV 0.23Q =

22 GeV 25Q =

ATT still small @ large and M2 due to slow evolution of

Large ATT expected[1] for and M2 not too large and � not too small

Drell-Yan Asymmetries — Polarised beam and target

)Q(x,h 2a1s

[1]M. Anselmino et al.,hep-ph/0403114

2GeV 30s =

2GeV 45s =

[ ]

[ ] �

�

�

�≈

+

+=

q2

p1

p2q

q2

p1q1

p1q

2q

TT x large

q2

p1

p2

p1

p2q

q2

p1q1

pq12

pq11

p1q

2q

TTTT )x(q)x(qe

)x(h)x(hea

)x(q)x(q)x(q)x(qe

)x(h)x(h)x(h)x(heaA

( )220

20

201q

[1] GeV/c 23.0Q @ )Qx,(q)Qx,(h Assuming =∆=

s

HESR:

ATT direct accessto valence quark h1

)x(h )x(h 21q11q VV×

0.3 M M

GeV 4530s 2J

2

2max

≥≥

÷=

Ψτ

Drell Yan Asymmetries — Unpolarised beam and target

��

���

++++

= cos2�sin2

cos��sin�cos13�

14�3

d�d

1 222

NLO pQCD: � ∼ 1, µ ∼ 0, � ∼ 0Experimental data [1]: � ∼ 30 %

[1] J.S.Conway et al., Phys. Rev. D39(1989)92.

� involves transverse spin effects at leading twist [2]:

cos2� contribution to angular distribution provide:

[2] D. Boer et al., Phys. Rev. D60(1999)014012.

)�,(xh )�(xh 211

22,1 ⊥

⊥⊥

⊥ ′×

Di-Lepton Rest Frame

Conway et al, Phys. Rew. D39 (1989) 92

Angular distribution in CS frame

E615 @ Fermilab

π-N → µ+µ-X @ 252 GeV/c

-0.6 < cosϑ < 0.64 < M < 8.5 GeV/c2

• cut on PT selects asymmetry• 30% asymmetry observed for π-

Angular distributions for Angular distributions for and and ππ-- —— π-N, N @ 125 GeV/cp p

E537 @ FermilabAnassontzis et al., Phys. Rew. D38 (1988) 1377

•ϑϑϑϑ

σσσσcosdd vs ϑϑϑϑcos

• ϕϕϕϕσσσσ

dd

vs ϕϕϕϕ

p

p−−−−�

−−−−�

Drell-Yan Asymmetries — Unpolarised beam, polarised target

��

���

+−+++∝ Λ)�sin(�sinS�cos2�sin2

cos1d�d

11S

21T

22

[ ]�

� ⊥⊥ ++

−=

a 2a

11a

12a

a 2a11

a122

a11

a11

2a

22S

1TT )(x)f(xfe

)(x)h(xhx)(x)f(xfxe

Q

Mcos1

)�sin(�2sin2SA 1

� ∼ 1, µ ∼ 0

Even unpolarised beam isa powerful tool to investigate�T dependence of QDF

D. Boer et al., Phys. Rev. D60(1999)014012.

vector couplings

same spinor structure

Drell-Yan Di-Lepton Production X���

Jpp −+→→

v�uM1

u�v �

2�v�ug

MMM1

u�vg �Vl

J2J

2�V

q

ΨΨΓ+− i

aa*�

TT

J

TT=Ψ

)x(u)x(u)x(h)x(h

a)x(q)x(qg

)x(h)x(hg

21

21u11u

x, xlarge TT

q 21Vq

q 21q11qVqJ

TT21

A ≈=��

Ψ

Measure ATT in J/� resonance

region in reactions

Cross section large enough in this region

~ 160 ev/day , <x>�0.4

2

1u

TT

TT

2J

F u(x))x(h

aA

s

M x, 0x

�

� �

�≅�≅≅ Ψ

↑↑pp

contrib.) (cont. GeV 10 6.9dMdMd

scm 10 1.5 GeV 45s 16

6

2-7-22

-1 -2312

� ≅

==

σL

( )( )days 240 %90P %5P

NPP

1� 11%�

pp

ppATT

≅≅

���

����

=≅

�������������� ���������� ���

Hyperon production Spin Asymmetries

Λ production in unpolarised pp-collision:

Several theoretical models:• Static SU(6) + spin dependence in parton fragmentation/recombination [1-3]

• pQCD spin and transverse momentum of hadrons in fragmentation [4]

[1] T.A.DeGrand et al.,Phys. Rev D23 (1981) 1227.[2] B. Andersoon et al., Phys. Lett. B85 (1979) 417. [3] W.G.D.Dharmaratna, Phys. Rev. D41 (1990) 1731.[4] M. Anselmino et al.,Phys. Rev. D63 (2001) 054029.

�)(N�)(N�)(N-�)(N

cosP1

AB

N↓↑

↓↑

+=

( ) ( )[ ]�cosAP1P�cosAP1P�cos2P

1D NBNB

BNN −−+= ↓Λ↑Λ

Analysing power

Depolarisation

Key to distinguish between these models

Data available for DNN:

3.67 GeV/c DNN < 0

13.3 -18.5 GeV/c DNN ~ 0

200 GeV/c DNN > 0

DNN @ 40 GeV/c MISSING

Hyperon production Spin Asymmetries

Polarised target: .

Transverse target polarisation

Existing data: PS185 (LEAR) [2]

[1] K.D. Paschke et al., Phys. Lett. B495 (2000) 49.[2] PS185 Collaboration, K.D: Paschke et al., Nucl. Phys. A692 (2001) 55.

��pp +→↑

[1] complete determination of the spin structure of reaction

Models account correctly for cross sections.

Models do not account for or .

NEW DATA NEEDED

�

NND �

NNK

Transverse Single Spin Asymmetries

↓↑

↓↑

−−=

dddd

AN �Xpp →↑ �Xpp →↑

• π Production @ large xF originate from valence quark:π+: AN > 0 ; π-: AN < 0 Correlated with expected u and d-quark polarisation

• AN similar for ranging from 6.6 up to 200 GeV

AN related to fundamental properties of quark distribution/fragmentation

New experiment with polarised nucleon target, and in a new kinematical region:

• new data available

• vs

• DY-SSA (AT) possible only @ RICH, p�p-scattering:

@ smaller s >> @ large s

p

�Xpp N,A

→↑

DYpp

DYpp

s

�Xpp N,A

→↑

����� ππππ� ��

E704 Tevatron FNAL 200GeV/c

Electromagnetic form-factors

FF in TL region ( ) related to nucleon structure

New information with respect to SL FF (eN-scattering)

TL - FF:

:

• low statistic• no polarisation phenomena

−+→ ��pp •

• analysing powerd�d

alternative way to FF

−+→ eepp

angular distribution separation of electric and magnetic FFanalysing power transverse polarisation of target p� leads

to non zero analysing power

Different prediction for models well reproducing SL data

Beam and Target

����������

����������

����� ��

������ ��

������������ � ����� ����� �� ������������������� �������� �������������� ��� ������ �� � ���� ����� ���� �������� �

Beam and Target

HESR:

Excellent but do not fit key requirement:

E > 40 GeV

PANDA:

4

1232

p

10p�p

scm102L

GeV5.14E

−

−−

±≤

⋅≤

=

design not compatible with polarised target

SIS300:• , slow extraction

• , largely enough

• accumulation rate• injection/extraction efficiency ~ 0.9

GeV40Ep ≥4102p

�p −⋅≈

sp105.1 7⋅/hp107 10⋅

Beam and Target - ASSIA

NH3 10g/cm3 : 2 x 10cm cells with opposite polarisation

GSI modifications:• extraction SIS100 � SIS300 or injection CR � SIS300

• slow extraction SIS300 � beamline adapted to

• experimental area adapted to handle expected radiation from

GeV40Ep ≥

173

f = 85.0PT ≈

1231723 sm105.1105.110610173

L −−⋅=⋅⋅⋅⋅⋅=

sp102 7⋅

Beam and Target - ASSIA

TARGET COMPASS likeTransverse and longitudinal polarisation

BEAM high luminosity and intensity Eventually polarised -beam from SIS300

UNIQUE TOOL TO INVESTIGATENUCLEON STRUCTURE

pp

Alternative GSI solution - ASSIA

• Luminosity comparable to external target � KEY IUSSUE • dilution factor f~1• difficult to achieve polarisation Pp ~ 0.85• required achievable with present HESR performances

(15 GeV/c)• only transverse asymmetries can be measured• p�-beam required polarisation proton source and acceleration scheme preserving polarisation

• no additional beam extraction lines needed• EXPERIMENTAL SETUP COMPLETELY DIFFERENT

HESR colliderpolarised p and beamsp

s

GeV/c15 Pp ≥

Experimental setup - ASSIA

Possible setup scheme similar to the COMPASS first spectrometer

• SM1 magnet ( 1Tm, stands )

• GEM,MICROMEGA detetors smaller angle

• MWPC, STRAW detectors larger angle

• expected resolution

• vertex resolution

• HODOSCOPEs � Trigger

• sandwiches iron plates, Iarocci tubes, scintillator slabs� µId

• beam vacuum pipe along the apparatus

/sp101.5 7⋅

�m 70 ≤

mm 1.5 ≤ΛΛ, 2MeV/c 2.5 ≈

cm 1 mm 2 ÷=

Sketch of the apparatus - ASSIA

MINIDC : drift type detectors like GEMs and µMEGADC : small drift type high spatial resolution detectors

+ larger detectors with dead central area

POLARISED INTERNAL TARGET “A LA HERMES”

Detector

Beam

TargetSource

Polarimeter

Storage Cell

Beam and Target - PAX

Hidrogen/Deuterium

Longitudinal Polarisation: P � 0.85

Transverse Polarisation: P � 0.80

Sketch of the apparatus - PAX

Forward detector(±8o acceptance) a la HERMES

• Identify unambiguously leading particles

• Measure precisely their momenta

Central Large Acceptance Detector a la E835

• Measure angles and energies of medium energy electromagnetic particles

Main goal: spin physics nucleon structureDY di-lepton production distribution functionsSpin observables in hadron production fragmentationElectromagnetic form factors

Ideal tools: polarised beam, polarised nucleon target

Key issue: in CM frame to span large x1,x2 domain

Summary

s

Slow extraction from SIS300

polarised target, both PL and PT

HESR (collider)

no diluition factor

pp −

MORE WORK, SIMULATIONS NEEDEDDISCUSSION WITH GSI MANAGEMENT:

• what is feasable• physics iussues

p