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

Introduction • SIS300 @ GSI:

• A complete description of nucleonic structure requires:@ leading twist and @ NLO

Physics objectives:

proton and gluon distribution functions

quark fragmentation functions

Drell-Yan di-lepton production

Single spin asymmetries

Spin observables in , production

Time like electromagnetic form factors

GeV/c40,p Pp

f1, g1 studied for decades: h1 essentially unknown

)kx,(fkd)x(f T1T2

1

Twist-2 PDFs

κT-dependent Parton Distributions

Distribution functions

Chirality

even odd

Twist-2

U

L

T

f1

g1

, h1,

h1

h1L

h1T

f 1T

g1T

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 Xμμpp

p

q2P

Mx

1

2

1

xxx 21F

q2P

Mx

2

2

2

s

Mxxτ

2

21

0QM 22

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

plane plane

*γp

*γ

Scaling:

Full x1,x2 range .

needed

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

Drell-Yan Di-Lepton Production Xμμpp

a 2

aa2

a1

a2a

212

2

F2

2

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

1

s9M

π4α

dxdM

σd

0,1τ

s

1

dxτd

σd

F

2

Gev/c 40pBEAM

1

Xμμppnb 0.3σ

Drell Yan Asymmetries — Unpolarised beam and target

θcos2φsin

2

νθcosφμsinθλcos1

3λ

1

4π

3

dΩ

dσ

σ

1 222

NLO pQCD: λ 1, 0, υ 0Experimental data [1]: υ 30 %

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

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

cos2φ contribution to angular distribution provide:

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

)κ,(xh )κ(xh 211

22,1

Di-Lepton Rest Frame

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

Angular distribution in CS frame

E615 @ Fermilab

-N +-X @ 252 GeV/c

-0.6 < cos < 0.6

4 < M < 8.5 GeV/c2

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

Drell-Yan Asymmetries — Unpolarised beam, polarised target

)φθsin(φsinSρθcos2φsin

2

νθcos1

dΩ

dσ

σ

11S

21T

22

a 2a

11a

12a

a 2a11

a122

a11

a11

2a

22

S1TT )(x)f(xfe

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

Q

M

θcos1

)φθsin(φ2sin2SA 1

λ 1, 0

Even unpolarised beam isa powerful tool to investigate

кT dependence of QDF

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

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 )()(

)()(

θcos1

θcos2φsin

xfxfexhxheA

a 2

a

11

a

1

2

a

a 2

a

11

a

L2

a

T21

a

1

2

a

22LT )()(

)()(1-)()(

Q

M

θcos1

cosφ 2sin2θ

xfxfexhxhxxgxxge

A

To be corrected for:

NH3 polarised target:TB PfP

1

60.1717

3f

0.85PT

Beam and Target

ASSIA

?

?

Beam and Target

SIS 100 Tm

SIS 300 Tm

U: 35 AGeV

p: 90 GeV

Key features:Generation of intense, high-quality secondary beams of rare isotopes and antiprotons.Two rings: simultaneous beams.

Sketch of the apparatus

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

+ larger detectors with dead central area

Experimental setup

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 → Id

• beam vacuum pipe along the apparatus

/sp101.5 7

μm 70σ

mm 1.5σ , 2MeV/c 2.5σ

cm 1 mm 2σ

Beam and Target

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

17

3f 85.0PT

1231723 sm105.1105.11061017

3L

sp102 7

Alternative GSI solution

• 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 collider polarised p and beams p

s

GeV/c15 Pp

Fermilab E866

800 GeV/c

30

456080

no K-factor, continuum contribution only

∫dM2 between 6 and 16 = (2.6, 7.8, 13, 20) 10-7 GeV-2

Phase space for Drell-Yan processes

30 GeV/c

15 GeV/c

40 GeV/c

= const: hyperbolaexF = const: diagonal

PANDA

ASSIA

A. Bianconi (ASSIA col.)

REQUIREMENTS FOR THE DRELL-YAN MODEL

Here, as well as in the parton model, Impulse approximation is required

dilepton mass M² large, s very large, but M² /s finite

“If we want to find processes which satisfy the kinematical constraints allowing application of the impulse approximation we need look for interactions at high energies s which absorb or produce a lepton system of huge mass M² such that the ratio M² /s is finite“.

S.D. Drell and T.-M. Yan Phys. Rev. Lett. 25 (1970) 316

Therefore s must be of the order of 100, that is T ≥ 40 GeV for M² in the `safe` region. No data below T= 30 GeV

Other possibility: the collider mode luminosity?