1. Hadron structure study in forthcoming Drell-Yan experiments
Oleg Denisov
CERN/INFN sez. di Torino
07/04/2020
Oleg Denisov

2. Outline Drell-Yan kinematics Unpolarised Drell-Yan
Single (Transverse) polarised Drell-Yan
Double polarised Drell-Yan
J/Psi production and J/Psi <-> DY duality
Access to GPDs?
Some indications to the future Drell-Yan experiments
Future Drell-Yan experiments:
Fixed target experiments (COMPASS, E906, J-Park)
Collider experiments (RHIC, NICA SPD (Dubna), PAX (GSI)
Some conclusions
07/04/2020
Oleg Denisov

3. Drell-Yan Kinematics (collinear case)
S.Melis -> COMPASS
07/04/2020
Oleg Denisov

4. Drell-Yan Kinematics (transverse motion)
07/04/2020
Oleg Denisov

5. Unpolirised Drell-Yan angular distributions
07/04/2020
Oleg Denisov

6. Unpolarised Drell-Yan angular distributions: Lam-Tung sum rule violation
07/04/2020
Oleg Denisov

7. Unpolarised Drell-Yan angular distributions: Boer-Mulders function (cos(2ϕ) modulations)
07/04/2020
Oleg Denisov

8. Drell-Yan cross section
07/04/2020
Oleg Denisov

9. Single polarised Drell-Yan: cross section
07/04/2020
Oleg Denisov

10. Single polarised Drell-Yan: cross section
07/04/2020
Oleg Denisov

11. Sivers effect SIDIS <->DY
A. Schafer – Mainz’09
J.C. Collins, Phys. Lett. B536 (2002) 43
Special thanks to A.V.Efremov
J. Collins, talk at LIGHT CONE 2008

12. Double polarised Drell-Yan: direct access to Transversity
M.Nekipelov -> PAX
Feasibility study is underway, polarised antiprotons(>20%) - not at all trivial issue
07/04/2020
Oleg Denisov

13. J/Y – Drell-Yan duality I
J/Y – DY duality  close analogy between Drell-Yan and J/Y production mechanism:
Occurs when the gluon-gluon fusion mechanism of the J/Y production is dominated by the quark-quark fusion mechanism
We can expect that the duality is valid in the COMPASS cinematic range
Key issue for the applicability of the J/Y signal for the study of hadron spin structure
J/Y production mechanism by itself is an important issue
  J/ substitution
07/04/2020
Oleg Denisov

14. Experiment: Only 2 points.
Therefore test DY and J/Y duality is of crucial importance in polarized case!
Transversity and Boer-Mulders PDFs from J/Y production with low s (duality model)
N. Anselmino, V. Barone, A. Drago, N. Nikolaev, Phys. Lett. B594 (2004) 1997
V. Barone, Z. Lu, B. Ma, Eur. Phys. J. C49 (2007) 967
A. Sissakian, O. Shevchenko, O. Ivanov, JETP Lett 86 (2007) 751
Ratios of cross­sections calculated with two models in comparison with the experimental data. Solid line corresponds to the ``duality'' model. Dashed line corresponds to the ``gluon evaporation'' model Dot­dashed line corresponds to ``gluon evaporation'' model without gluon contribution.
Tests on the models for unpolarized J/Y production (gluon evaporation, NRQCD, ...)
- COMPASS
- NICA 14

15. Drell-Yan processes and access to GPDs
Very preliminary – feasibility is under discussion now, some indications:
O.Teryaev: Drell-Yan pair production in the pion-nucleon collisions for large xF (the region whose exploration is favourable in COMPASS kinematics) is sensitive to such an important and hot ingredient of pion structure as its light-cone distribution (DA). In other words in this kinematic range pion participate in the interaction coherently (as pion) rather then by only one of its quark.
References:
A.P.Bakulev, S.V.Mikhailov and N.G.Stefanis, Phys.Lett.B 508, 279 (2001)
A.Brandenburg, S.J.Brodsky, V.V.Khoze and D.Mueller, Phys.Rev.Lett. 73, 939 (1994)
A.Brandenburg, D.Mueller and O.V.Teryaev, Phys.Rev.D 53, 6180 (1996)
B.Pire, O.Teryaev: Semiexclusive DY – crucial test of the GPDs universality (time-like process contrary to the Deep Inelastic scattering)
Reference:
B.Pire, L. Szymanowski, arXiv: v1 [hep-ph] 8 May 2009
07/04/2020
Oleg Denisov

16. GPD’s universality test ?
07/04/2020
Oleg Denisov

17. Semiexclusive Drell-Yan?
In the COMPASS case the (semi)exclusivity is provided by a simple cut on missing mass
07/04/2020
Oleg Denisov

18. Some indications for the future Drell-Yan experiments
TMD PDFs – ALL are sizable in the valence quark region
Sivers effect in Drell-Yan processes.
M. Anselmino, M. Boglione U. D'Alesio, S. Melis, F. Murgia, A. Prokudin 
Published in Phys.Rev.D79:054010, 2009
07/04/2020
Oleg Denisov

19. Some indications for the future Drell-Yan experiments
Safe region: 4. < M < 9. Gev/c2
07/04/2020
Oleg Denisov

20. Some indications for the future Drell-Yan experiments
High luminosity (DY Cross Section is a fractions of nanobarns) and large angular acceptance, better pion or antiproton beams (valence anti-quark)
Sufficiently high energy to access ‘safe’ of background free Mll range ( 4 GeV/c < Mll < 9 GeV/c)
Good acceptance in the valence quark range xB > 0.05 and kinematic range: τ = xAxB = M2/s > 0.1
Polarised Drell-Yan:
Good factor of merit (Fm), which can be represented as a product of the luminosity and beam (target) polarisation (dilution factor) (Fm~ L × Pbeam (f))
07/04/2020
Oleg Denisov

21. Future Drell-Yan experiment
Fixed target experiments (COMPASS, E906, J-Park) characterised by:
Very high luminosity (>1033 cm-2s-1)
Only muon in the final state (hadron absorber has to be used because of the ‘all forward’ geometry and high luminosity)
Light unpolarised targets (liquid hydrogen and deuterium) and solid state polirised targets (NH3, 6LD)
Pion, proton and (probably) antiproton (COMPASS) beams
Collider experiments (RHIC, NICA SPD, PAX)
Moderate luminosity
High universality (not only TMD PDFs, J/Psi and related aspect but also formfactors, various hard processes – not a topic of this talk)
07/04/2020
Oleg Denisov

22. COMPASS experiment at CERN
07/04/2020
Oleg Denisov

23. Why Drell-Yan @ COMPASS
Large angular acceptance spectrometer
SPS M2 secondary beams with the intensity up to 6x107 particles per second
Large acceptance COMPASS Superconducting Toroidal Magnet
Transversely polarized solid state proton target with a large relaxation time and high polarization, when going to spin frozen mode;
a detection system designed to stand relatively high particle fluxes;
a Data Acquisition System (DAQ) that can handle large amounts of data at large trigger rates;
The dedicated muon trigger system
For the moment we consider two step DY program:
The program with high intensity pion beam
The program with Radio Frequency separated antiproton beam
07/04/2020
Oleg Denisov

24. DY cross section and acceptance @ COMPASS
C.Quintans -> COMPASS
07/04/2020
Oleg Denisov

25. DY acceptance @ COMPASS
Pure u-dominance
region
Prediction for Sivers function as a function of x, COMPASS acceptance in xp and acceptance coverage xπ.vs.xp
07/04/2020
Oleg Denisov

26. Access to the TMD PDFs @ COMPASS
07/04/2020
Oleg Denisov

27. Feasibility test @ COMPASS
07/04/2020
Oleg Denisov

28. Pt range covered by COMPASS
COMPASS Pt coverage
Previous experiments:
07/04/2020
Oleg Denisov

29. Sivers and expected statistical error @ COMPASS
07/04/2020
Oleg Denisov

30. COMPASS: Summary
Pion and, later, antiproton beams ( GeV), Drell-Yan process dominated by the contribution from the valence quarks (both beam and target), τ = x1x2 = Q2/s ≅ 0.05÷0.3
Solid state polarised targets, NH3 and 6LD, in case of hydrogen target – pure u-dominance
Statistical error on single spin asymmetries is on the level 1÷2%
LoI already submitted to CERN SPSC, ‘go ahead’ for full proposal is obtained
Start date ≥ 2012
07/04/2020
Oleg Denisov

31. Other fixed target experiments: E906 and J-Park
Luminosity ~ 1033 cm-2s-1
Beam energy – 120 GeV
Start dates > 2010
Unpolirised
Proton beam only
07/04/2020
Oleg Denisov

32. unique possibilities for the spin program:
NICA Facility at JINR Dubna
NICA could provide
unique possibilities for the spin program:
High energy proton
and deuteron beams
2. High luminosity ( > см-2с-1 for proton beam)
3. High polarization (>50% )
4. Spin rotation L/T
5. High precision of polarization measurements
6. 4  geometry detector
7. Possibility to change beams energy with ~1 GeV step
SPD
Source of Polarized Ions (CIPIOS based) for Nuclotron-M / NICA complex
will provide  d (p) /pulse
A.Nagaytsev -> NICA SPD 32 32

33. Polarized proton beams parameters @ NICA
Energy, GeV 5 12
Proton number per bunch
6E10
1.5E10
Rms relative momentum spread
10E-3
Rms bunch length, m
1.7
0.8
Rms (unnormalized) emittance, mmmrad
0.24
0.027
Beta-function in the IP, m
0.5
Lasslet tune shift
0.0074
0.0033
Beam-beam parameter
0.005
Number of bunches 10
Luminosity, cm-2∙s-1
1.1E30 33 33

34. NICA Spin Physics Detector (SPD)
SPD Group at JINR is working on the preparation of the spin physics program (LoI) for NICA to operate with polarized beams of light nucleus.
Studies of DY processes
Studies of J/Y production processes
Studies of elastic reactions
Polarimetry
Spin effects in one and two hadron production processes
Spin effects in photoproduction
Spin effects in various exclusive reactions
Spectroscopy of quarkonia with any available decay
modes
Diffractive processes
Hidden color in light nuclei
Color transparency
and others
(studies of unpolarized pp reactions:
direct photons, z-scaling etc) 34

35. Preliminary estimations of the Drell-Yan processes feasibility
NICA SPD - feasibility
Preliminary estimations of the Drell-Yan processes feasibility
DY cross sections (nb) in comparison with PAX (GSI,FAIR) and possibility to increase the statistics (month of data taking) 35

36. ACCESS to TMD PDFs – statistical errors estimare (very preliminary)
The set of original software packages (MC simulation, generator etc.) were developed for the feasibility studies of DY polarized processes (to be published)
The SSA asymmetries.
Top:access to transversity and Boer-Mulders PDFs (Sissakian, Shevchenko, Nagaytsev,PRD 72 (2005), EPJ C46 (2006))
Bottom: access to Sivers PDFs (Efremov,… PLB 612(2005), PRD 73(2006));
All SSA are estimated for 100 K DY events 36

37. Side view of the NICA SPD experimental set-up: for µ+µ- pairs
- Toroid magnet system
Silicon or MicroMega (Vertex)
Drift chambers (DC)
- EM Calorimeter (EMC)
Range System (RS)
JINR contribution on RS for PANDA
(G.Alexeev et al. Private commun.)
Trigger counters
EndCap detectors with RS,
tracking system and HCal/EMC
Range System
End Cap
EM Calorimeter
Sizes:
Inner barrel length: 160 cm
EMC ( ~ 50 cm):
inner radius: 52 cm
DC1 + Hod1: 102 cm
RS: 10 layers(3 cm Fe + 2 cm MDC)
inner rad: 120 cm
outer rad: 170 cm
Toroid Magnet
DC and Trigger
Vertex System 37

38. NICA SPD muon Range System
3 GeV muon
10 GeV pion shower
RS is accepted as main detector of Muon System for PANDA
(G.Alexeev et al. Private commun.)
RS can be used as:
1. Muon Filter
2. PID for protons and pions
3. To reduce background from muons produced by pion decays
4. Hadron Calorimeter with energy resolution ~ 100/sqrt(E)
Minor:
- Multiple Scattering
- Problem with PID for particles with momenta less than 1 GeV
Hardware tests RS+EMC at Nuclotron-M(JINR) or SPS(CERN)
Eπ=0.5 GeV
Muon energy, angle and
correlation distributions 38

39. Other Collider experiments
L ≈ 1031 cm-2s-1 (polarized pp)
s = 200 GeV
pp collision
x1x2 = 4×10-4 ÷ 1×10-2
201?
L = cm-2 s-1
S = 30 GeV2
ppbar collisions, e+e- final state
x1x2 = 0.2 ÷ 0.4
YEAR 202?

40. Drell-Yan experiments in the two next decades
European line:
COMPASS: pion beams ( GeV) on polarised solid state targets (NH3 and 6LD) (>2012)
NICA SPD: proton-proton (polarised) collider (>2014)
COMPASS: antiproton beam (~100 GeV) on polarised solid state targets (NH3 and 6LD) (>2015)
PAX (GSI) polarised proton – polarised antiproton collider (>2020, if feasibility is proved)
American-Japanese line:
RHIC: polarised proton-proton collisions, √s = 200GeV
E906: proton beam(120 GeV) on unpolarised 1H, 2H, and nuclear targets (>2010)
J-Park: proton beam (30 GeV) on unpolarised target (>2010)
J-Park: polarised proton beam on (un)polarised target (>20??)

41. Some conclusions
Next decade looks very promising for the new Drell-Yan experiments – a lot of activity in the field
The new generation of the polarised Drell-Yan programs will contribute in decisive way into our understanding of the hadron structure
Access to the valence quarks contributions as well as high luminosity seems to be an important prerequisits to the successful Drell-Yan experiment

42. Spares

43. 07/04/2020
Oleg Denisov

44. DUMP Momentum selection E.g. a system with two cavities: L RF2 RF1
WHAT ABOUT A RF SEPARATEDp BEAM ???
First and very preliminary thoughts, guided by
recent studies for P326
CKM studies by J.Doornbos/TRIUMF, e.g.
E.g. a system with two cavities: L
RF1
RF2
DUMP
DUMP
Momentum
selection
Choose e.g. DFpp
DF = 2p (L f / c) (b1-1 – b2-1) with b1-1 – b2-1 = (m12-m22)/2p2
L.Gatignon,
Preliminary rate estimates for RF separated antiproton beams

45. COMPASS wrt past DY experiments
07/04/2020
Oleg Denisov

46. Boer-Mulders in unpolarised DY at COMPASS
Flavor separation of the Boer-Mulders function from unpolarized pi- p and pi- D Drell-Yan processes.
Zhun Lu, Bo-Qiang Ma, I. Schmidt Phys.Lett.B639: ,2006
07/04/2020
Oleg Denisov