Feasibility Studies of Nucleon Structure Observables at PANDA at FAIR

Transcription

1 Feasibility Studies of Nucleon Structure Observables at PANDA at FAIR Alaa Dbeyssi On behalf of the PANDA collaboration Dileton Productions with Meson and Antiroton Beams ECT* Trento, 9 November 017 Helmhol' Institute Mainz Johannes- Gutenberg University Mainz

2 Outline Facility for Antiroton and Ion Research (FAIR) PANDA exeriment and hysics rogram Study of the nucleon structure at PANDA Electromagnetic form factors FFs Transition distribution amlitudes TDAs Generalized distribution amlitudes GDAs Transverse momentum deendence TMD-PDFs PANDA sectrometer and hases

3 Facility for Antiroton and Ion Research - FAIR (Darmstadt/Germany) APPA ions, antirotons PANDA antiroton beams Darmstadt, Germany CBM relativistic nuclear collisions NUSTAR radioactive ion beams 3

4 Facility for Antiroton and Ion Research - FAIR High Energy Storage Ring Antiroton beam:1.5 GeV/c 15 GeV/c 9 GeV rotons High Resolution (HR) Mode L= cm -1 s -1 o Electron cooling Δ/ High Luminosity (HL) Mode o L= 10 3 cm -1 s -1 o Stochastic cooling Δ/ 10-4 Internal target (bar-, bar-a): cluster jet / ellet target; high density 4x10 15 cm - 4

5 FAIR-HESR (Start version) Modularised Start Version (MSV) L ~ cm -1 s -1 and Δ/ ~ GeV rotons RESR will not be resent and its work will be done in the HESR The intensity in the HESR in the MSV0-3 is limited to bars due to the cooling and injection efficiencies RESR 5

6 The PANDA exeriment at FAIR antiproton ANnihilation at DArmstadt Hadron Sectroscoy and dynamics Charmonium Light mesons Gluonic exitations Oen charm (Multi) strange baryons Nucleon structure Hyernuclear hysics Threshold Hadrons in the nuclear medium s = [ ] GeV ArXiV:

7 Study of the Nucleon Structure at PANDA Crossing Symmetry Proton Electromagnetic Form Factors (FFs) Generalized Distribution Amlitudes (GDAs) Transverse Momentum Deendent Parton Distribution Functions (TMD-PDFs) Transition Distribution Amlitudes (TDAs) 7

8 Electromagnetic Form Factors of the Proton ScaRering Annihilation:Time- Like region π 0 e - FFs are real Sace- Like region 0 Unhysical region e + e π 0 e + e + FFs are comlex _ e + q Electric G E and magnetic G M roton FFs are analytical functions of the momentum transfer squared q Playground for theory and exeriment: - at low q, robe the size of the nucleus, - at high q, test QCD scaling 8

9 Electromagnetic Form Factors of the Proton F 1 10 G E = G M 1 10 A. Bianconi, E. Tomasi-Gustafsson Phys. Rev. Lett. 114,3301 (015) BaBar 013 Data 3 10 e + e PRL 114 (015) q [GeV ] No individual determination of G E and G M Stee behavior of the effective FF (G eff ) at threshold Structures aeared in BaBar data (PRD 87 (013) 09005)? 9

10 World data on the time- like roton form factor ratio R= G E / G M R 3.5 BaBar LEAR FENICE+DM E835 BESIII e + e BaBar (SLAC): Ø data collection over wide energy range e + PS 170 (LEAR): Ø data collection at low energies 1.5 CMD-3 Data from BaBar & LEAR show different trends e + BESIII: Ø Measurement at different energies Ø Uncertainties comarable to revious exeriments q [(GeV/c) BaBar: Phys. Rev. D LEAR: Nucl.Phys.J., B411: BESIII: arxiv: CMD- 3: arxiv: v (015) CMD- 3 (VEPP000 collider, BINP): Ø Energy scan s =1 GeV Ø Uncertaincy comarable to the measurement by BaBar 10

11 World data on the time- like roton form factor ratio R= G E / G M R BaBar LEAR FENICE+DM E835 BESIII CMD-3 e + e BaBar (SLAC): Ø data collection over wide energy range e + PS 170 (LEAR): Ø data collection at low energies Data from BaBar & LEAR show different trends e + BESIII: Ø Measurement at different energies Ø Uncertainties comarable to revious exeriments CMD- 3 (VEPP000 collider, BINP): q [(GeV/c) ] Ø Energy scan s =1 GeV PANDA: Measurement over wide range Ø Uncertaincy comarable to BaBar: Phys. Rev. D Test of theoretical models of q with high recision LEAR: Nucl.Phys.J., B411: measurement by BaBar & redictions! BESIII: arxiv: CMD- 3: arxiv: v (015) 11

12 Time- like electromagnetic roton form PANDA: The goals Ø Ø Form factor measurements different final states: l + l (l = µ, e) Ø Ø Ø Ø First time measurement with muons in final state Study of radiative corrections Consistency check of roton form factor data Test of leton universality Possibility to access the relative hase of roton time- like form factors: l + l in the Born aroximation: Ø Unolarized cross section - > access to G E & G M Ø Polarization observables - > access to relative hase G E G M *: Single sin olarization observable " dσ % $ ' # dω& 0 * A 1,y sinθim( G M G E ) Ø A. Z. Dubnickova, S. Dubnicka & M.P. Rekalo Nuovo Cim. A109 (1996) Ø Develoment of a transverse olarized target for PANDA in Mainz 1

13 Time- like electromagnetic roton form PANDA: The goals Ø Access the unhysical region (R= G E / G M and relative hase between G E and G M ) : π 0 e + e Ø M. P. Rekalo, Sov. J. Nucl. Phys. 1 (1965) 760 Ø C. Adamuscin, E.A. Kuraev, E. Tomasi- Gustafsson and F.E. Maas, Phys. Rev. C 75, (007) Ø Feasibility studies by J. Boucher, M. C. Mora- Esi; PhD thesis Ø Measurement of time- like roton form factors over wide range of PANDA Ø Study the asymtotic behavior of the form factors Ø Strong hadronic background, mainly σ ( π + π ) σ ( l + l ) $ % & ' Good background rejection necessary π + π, π + π π 0 Ø E.W. Singh et al.: EPJA5, 35 (016) Feasibility studies needed for both signal channels! 13

14 Feasibility studies: time- like roton form PANDA Simulation & Analysis: Background studies π + π π + π beam = 1.7 GeV/c Ø New event generator develoed by Mainz grou (M. Zambrana et al.) Ø Based on two different arametrizations π beam = 5.0 GeV/c θ CM P beam = 6.1 GeV/c π + σ ( π + π ) σ ( l + l ) [ ] cosθ CM Ø Background rejection ~10-8 needed: Pollution < 1% Ø J. Van de Wiele and S. Ong: EPJA46, (010) Ø M. Sudol et al.: EPJA44, 373 (010) Ø E.W. Singh et al.: EPJA5, 35 (016) 14

15 Feasibility studies: time- like roton form PANDA Monte Carlo Simulation Studies l + l (l = e,µ) π + π Standard chain Simulation & Analysis with PANDARoot: Event generation Digitization Reconstruction Particle Identification Event Analysis beam [GeV/c] s [GeV] Event selection: Ø Preselection: One ositive and one negative article er event Ø Cuts on kinematical variables: Production angles (back- to- back in center- of- mass system), & Invariant Mass. Ø Signal/Background searation based on: Ø For e + e - : Different subdetector information like Electromagnetic Calorimeter, Straw Tube Tracker etc. contribute to article identification Ø For µμ + µμ - : Boosted Decision trees + cuts Detector information MAINLY from Muon Range System 15

16 A) Feasibility studies: time- like roton form PANDA for e + e Ø Study of recision for G E & G M, the form factor ratio R & effective form factor Ø Study of the systematic effects : generator model, fluctuations and fit function Ø Method I: event generator based on hysical cross section & exected events are simulated Ø Method II: 10 6 events + flat Phase Sace (PHSP) event generator + weighting 16

17 A) Feasibility studies: time- like roton form PANDA Signal efficiency & Background rejection Method I e + e e + e Signal: Ø Zichichi cross section 1 + PHOTOS Ø Assuming R = G E G M =1 Ø s [GeV ]: 5.4, 7.3, 8., 11.1, 1.9, 13.9 Ø Additional samles for signal efficiency determination ~10 6 events Ø High signal efficiencies between 39% and 51% π + π Background: Ø New event s = 5.4, 8., and 13.9 [GeV ] Ø 10 8 events at each energy oint Ø Background rejection ~ 10-8 Signal ollution < 1% Efficiency corrected events cosθ 0.8 Ø Extraction of FF s & R± R from efficiency corrected signal distribution Ø Time- integrated cross section of { - 1 1) A. Zichichi, S. M. Berman, N. Cabibbo, R. GaRo, Nuovo Cim. 4, (196)

18 A) Feasibility studies: time- like roton form PANDA Statistical and total uncertainty on R, G E and G M Results Statistical relative uncertainty v G E / G E : 0.9% - 48% v G M / G M : 0.4% - 9.4% v R/R : 1.3% - 56% Ø The recisions obtained at 5.4 GeV and 8. GeV are comatible between Method I & II R e + e 3.5 L= fb -1 BaBar LEAR FENICE+DM E835 BESIII CMD-3 PANDA Method I PANDA Method II Ø Systematic uncertainties are considered from luminosity measurement & background contamination Total relative uncertainty v G E / G E :.% - 48% v G M / G M : 3.5% - 9.7% v R/R : 3.3% - 57% s [GeV ] Ø E.W. Singh et al.: EPJA5, 35 (016) 18

19 B) Feasibility studies: time- like roton form PANDA for µ + µ Study of the statistical error on R, G E & G M 19

20 B) Feasibility studies: time- like roton form PANDA Statistical error on R = G E / G M µ + µ Signal: µ + µ Ø Follows hysical cross section Ø Assuming Analysis : Boosted Decision Trees & Cuts R = G E G M =1 Ø s [GeV ]: 5.4 (5.1, 6.8, 8.) Ø Additional samles for signal efficiency determination ~10 7 events counts Generated events Efficiency corrected events Fit function ~ dσ/dcosθ cosθ 0.8 Ø Signal efficiency ~ 1% π + π Background: Ø New event s [GeV ]: 5.4 (5.1, 6.8, 8.) Ø Two samles each for studying background rejection and effects of background subtraction, 10 8 events at each energy oint cos( CM ) Ø Background rejection factor ~ 10-6 Ø Background subtraction removes ion background contamination Ø Extraction of FF s & R± R from efficiency corrected signal distribution Ø Time- integrated cross section of { - 1 0

21 Feasibility studies: time- like roton form PANDA Statistical error on R, G E & G M µ + µ World data on R = G E / G M R BaBar LEAR FENICE+DM E835 BESIII CMD-3 PANDA sim muon L= fb -1 Precision on R, G E & G M [GeV/c] 1.7 R/R 5.1% G E / G E 8.6% G M / G M 4.1% - PRELIMINARY s [GeV ] 1

22 Transition Distribution Amlitudes

23 Nucleon to meson TDAs New class of non-erturbative structure functions Occur in collinear factorization descrition of various hard exclusive rocesses Are indeendent of reaction tye, s and q Give information on ionic comonents of the nucleon wave-function 3

24 Nucleon to meson TDAs at PANDA γ * π 0 > e + e π 0 ( this rocess never been measured) Hard scale: large q ~s t is small (forward kinematics) u is small (backward kinematics) J. P. Lansberg et al., Phys Rev D 76, 11150(R) (007) Feasibility studies of measuring γ * π 0 > e + e π 0 at PANDA Luminosity= u - 1 π + π π 0 Background suression of the [σ(π + π - π 0 )/σ(e + e - π 0 )~10 6 ]: s = 5 GeV : at low q ( at high q ) s = 10 GeV : at low q ( at high q ) Eur.Phys.J. A51 (015) 8, 107 4

25 Nucleon to meson TDAs at PANDA dσ dq ~ 1 Fit measured cross section and measure scaling comonent A (A=5) (q ) 5 à Test QCD factorization L= fb -1 Δσ /σ ~ 1% L= fb -1 Δσ /σ ~ 4% Eur.Phys.J. A51 (015) 8, 107 5

26 Nucleon to meson TDAs at PANDA J /ψπ 0 > e + e π 0 t is small (forward kinematics) u is small (backward kinematics) B. Pire et al., Phys. LeR. B (013) High signal cross section Large q fixed to Q = M J/ψ = 9.6GeV (factorization theorem is likely reached) Reduces uncertainty on DAs by using the data on the J /ψ > artial decay modes Comlementary measurements: test of universality of TDAs by comaring to γ * π 0 > e + e π 0 at different q 6

27 counts LAB Nucleon to meson TDAs at PANDA = 5.5 GeV/c counts LAB J /ψπ 0 > e + e π 0 = 8.0 GeV/c counts LAB = 1.0 GeV/c Validity ranges of the TDA model: t is small (forward kin.) 00 Fwd. Kin Bwd. Kin θ LAB [deg] θ LAB [deg] θ LAB [deg] u is small (backward kin.) Background final states: Three ion roduction: π + π - π 0 (B/S~ ) Multiion final states (N>3): π 0 π 0 π + π -, π 0 π + π - π + π - π 0 (B/S~3-15) Dielectron continuum :γ π 0 - >e + e - π 0 Annihilation into π 0 π 0 J/ψ Hadronic decays of J/ψ Phys. Rev. D 95, (017) 7

28 eff. corr. yield 3 10 LAB = 5.5 GeV/c 1.5 ("small t") 1 Nucleon to meson TDAs at PANDA eff. corr. yield 3 10 LAB = 8.0 GeV/c ("small t") J /ψπ 0 > e + e π 0 eff. corr. yield 3 10 LAB = 1.0 GeV/c 1.5 ("small t") 1 Fit funtion: B (1+ Acos e θ + J/ψ ) 0.5 A = 1.1 ± 0.9 Eff. corrected yield Background 0.5 A = 1.00 ± 0. Eff. corrected yield Background 0.5 A = 0.74 ± 0.7 Eff. corrected yield Background eff. corr. yield cos(θ) 3 10 LAB = 5.5 GeV/c 1.5 ("small u") A = 1.19 ± 0.8 Eff. corrected yield Background eff. corr. yield cos(θ) 3 10 LAB = 8.0 GeV/c ("small u") 1.5 A = 0.75 ± 0.30 Eff. corrected yield Background eff. corr. yield cos(θ) L= fb -1 Δσ (t,u) /σ (t,u) ~ 5% 10% 3 10 = 1.0 GeV/c 1.5 LAB ("small u") A = 1.77 ± 1.57 Eff. corrected yield Background Phys. Rev. D 95, (017) cos(θ) cos(θ) cos(θ) 8

29 Generalized Distribution Amlitudes 9

30 Hard exclusive rocesses at PANDA- GDAs γ γ bar γγ γ γ large hoton transverse momentum (hard scale) GDA γ GP D QCD factorization γ Wide Angle Comton Scattering Generalized Parton Distributions GPDs Time-Like Wide Angle Comton Scattering Generalized Distribution Amlitudes GPDs GDAs can be measured at PANDA with the hard exclusive electromagnetic rocesses: bar γγ, γμ (Μ=π 0,,η,ρ 0,φ) PANDA measurements are comlementary to the results from the deely virtual Comton scattering (DVCS), the deely virtual meson roduction (DVMP), the time-like Comton scattering using real hoton beams, and leton-air roduction with meson beams. 30

31 Feasibility studies for GDAs measurement at PANDA 4 different CM energies Main background channels: π 0 π 0 π 0 γ (for both signals) (for signal1: ) PANDA Physics Performance Reort arxiv: Preliminary studies π 0 γ π 0 π 0 γγ S/B~1 (5% signal efficiency) S/B~ (50% signal efficiency) 31

32 Transverse Momentum deendence - Parton Distribution Functions 3

33 Drell- Yan at PANDA e e X SIDIS q l + X q l TMD PDF TMD-PDFs are convoluted with the fragmentation functions h X Direct access to TMD-PDFs Test of Universality and the QCD TMD factorization 33

34 Drell- Yan at PANDA: TMD- PANDA energy range u to s~30 GeV : access to a unique kinematic region where valence quark effects dominate In bar annihilation each valence quark can contribute to the DY diagram Asymmetry measurements: Transversity Sivers Boer-Mulders (BM) Unolarized Drell Yan A cosϕ h 1 Single-olarized Drell Yan A sin(ϕ±ϕs) h 1, h 1T, f 1T ϕ : angle between hadron and leton lanes ϕ s : angle between hadron sin and leton lane 34

35 Feasibility measurement of Drell Yan rocesses at PANDA Monte-Carlo simulations: Signal: µ + µ X µ + µ X Unolarized DY Single-olarized DY Main background: n(π + π )X, required rejection factor ~10 7 s=30 GeV and 1.5 M γ *.5 (large cross section) Number of simulated events N~ Preliminary studies PANDA Physics Performance Reort arxiv: q T GeV/c q T 3 GeV/c x : the longitudinal momentum of the hadronic robe q T : transverse momentum of the muon air A. Bianconi event generator Phys. Rev. D 71, (005) 35

36 Feasibility measurement of Drell Yan rocesses at PANDA Monte-Carlo simulations: Signal: µ + µ X µ + µ X Unolarized DY Single-olarized DY Main background: n(π + π )X, required rejection factor ~10 7 s=30 GeV and 1.5 M γ *.5 (non resonance region, large cross section) Number of simulated events N~ Preliminary studies PANDA Physics Performance Reort arxiv: Accetance, efficiency corrections, background rejection are still under 1 q T GeV/c investigation: exectation: ~ DY/month q T 3 GeV/c Few months of data taking (L= cm - s -1 ): recise measurements of the azimuthal asymmetries are ossible x Feasibility : the longitudinal studies momentum for measuring of the Drell hadronic Yan rocesses robe at PANDA are ongoing q T : transverse momentum of the muon air 36

37 Detector requirements from hysics case 4π accetance Momentum resolution: 1% central tracker in magnetic field Photon detection: 1 MeV - 10 GeV high dynamic range good energy resolution Particle identification: γ, e, µ, π, K, Cherenkov detector time of flight, de/dx, muon counter Dislaced vertex info cτ = 317 µm for D± γβ Cross section for electromagnetic Processes 37

38 The PANDA detector (start/full setu) 38

39 The PANDA hases 39

40 Summary Proton form factors can be measured at PANDA in the time- like region and over a large kinematical region through: e + e µ + µ e + e π 0 PANDA will rovide valuable measurements for the test of universality of TDAs through: γ * π 0 > e + e π 0 J /ψπ 0 > e + e π 0 PANDA exeriment will rovide a comlementary study of the nucleon structure with the hard inclusive and exclusive rocesses: Generalized Distribution Amlitudes (GDAs), (TMD) Parton Distribution Functions, and Transition Distribution Amlitudes (TDAs) Ø Physics Performance Reort for PANDA: Strong Interaction Studies with Antirotons, arxiv: Ø [PANDA Collaboration], Phys. Rev. D 95, (017) Ø [PANDA Collaboration], Eur. Phys. J. A 5, 35 (016) Ø [PANDA Collaboration], Eur. Phys. J. A 51, 107 (015) 40

41 Back- u slides 41

42 Feasibility studies: time- like roton form PANDA Conclusion B) Feasibility studies for the signal reaction µ + µ Ø Monte Carlo simulation & analysis for signal and main background channel = 1.7 GeV/c a recision on µ + µ π + π Ø R of 5.1%, Ø G M of 4.1% & G E of 8.6% could be achieved L= fb -1 Ø Comlete study for the muonic channel for beam momenta of 1.5, 1.7,.5 and 3.3 GeV/c currently under review Ø Phase- 1 simulations (reduced luminosity & reduced PANDA detector setu) lanned The time- like electromagnetic roton form factors and their ratio R= G E / G M can be PANDA with unrecedented statistical accuracy 4

43 Time- like electromagnetic roton form PANDA: The goals Ø Differential cross section 1 of signal reaction l + l l = µ, e Access to the time- like, electromagnetic form factors of the roton, G E and G M : dσ β l G M d cosθ CM β s $ &(1+ 4m l & % s ' + β l cos θ CM )+ R τ (1 β cos θ l CM )) ) ( Ø High luminosity: Measurement of signal angular distribution Ø Searate determination of G E, G M over a large kinematical region in the time- like region Ø High recision measurement of the ratio R = G E / G M at PANDA as well as the roton effective form factor F σ tot R = G E G M 1) A. Zichichi, S. M. Berman, N. Cabibbo, R. GaRo, Nuovo Cim. 4, (196)

44 Electromagnetic Form Factors of the Proton Ø Describe the internal structure and dynamics of the roton Ø Hadronic current µ J had (q =! ) = (!) j µ () = e u(!) Γ µ (q) u() Ø Hadronic vertex can be arametrized in terms of Dirac and Pauli Form Factors F 1 & F : Γ µ = F 1 (q ) γ µ + iσ µν q ν M F (q ) Ø F 1 and F are real functions of q SPACE- LIKE region Real FFs e- Sca ering e e q < 0 ` γ µ ` g (q) Γ µ (q) 0 q Ø Sachs Form Factors G E (q ) = F 1 (q ) + q 4m G M (q ) = F 1 (q ) + F (q ), F (q ), G E (0) =1 G M (0) = µ Ø In the Breit frame q = (0, q) and in non relativistic aroach, the FF s reresent the Fourier transforms of electric charge and magnetization satial distribution of the nucleon 44

45 Nucleon to meson TDAs at PANDA J /ψπ 0 > e + e π 0 ] dσ J/ψ-π 0/du[b/GeV LAB = GeV/c Eff. corrected MC TDA model u[gev ] ] dσ J/ψ-π 0/du[b/GeV LAB = 8.0 GeV/c Eff. corrected MC TDA model u[gev ] ] dσ J/ψ-π 0/du[b/GeV LAB = 1.0 GeV/c 00 Eff. corrected MC 180 TDA model u[gev ] ] dσ J/ψ-π 0/dt[b/GeV 300 Eff. corrected MC LAB = GeV/c TDA model t[gev ] ] dσ J/ψ-π 0/dt[b/GeV LAB = 8.0 GeV/c Eff. corrected MC TDA model t[gev ] ] dσ J/ψ-π 0/dt[b/GeV LAB = 1.0 GeV/c Eff. corrected MC TDA model t[gev ] 45