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Mitglied der Helmholtz-Gemeinschaft The Hadron Physics Program at COSY-ANKE : selected results June 26, 2013 | Andro Kacharava (JCHP/IKP, FZ-Jülich) Baryons2013.

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Presentation on theme: "Mitglied der Helmholtz-Gemeinschaft The Hadron Physics Program at COSY-ANKE : selected results June 26, 2013 | Andro Kacharava (JCHP/IKP, FZ-Jülich) Baryons2013."— Presentation transcript:

1 Mitglied der Helmholtz-Gemeinschaft The Hadron Physics Program at COSY-ANKE : selected results June 26, 2013 | Andro Kacharava (JCHP/IKP, FZ-Jülich) Baryons2013 International Conference on the Structure of Baryons June 24 th – 28 th 2013, Glasgow

2 Outline Introduction Overview of the program Experimental facilities (COSY, ANKE) SPIN physics program: selected results Nucleon-Nucleon scattering Pion production Hyperon-Nucleon interaction Future measurements

3 Introduction: Program overview Goal: Study of 3-body final states aiming to extract basic spin-dependent two-body scattering information Tools: Hadronic probes (p,d) Double polarization (beam and target) Topics: 1. NN scattering pp- and np-amplitudes, nuclear forces 2. Meson production NNπ amplitudes (PWA), ChPT 3. Strangeness production YN interaction, N scattering lengths COSY proposal #152 ArXiv:nucl-ex/0511028

4 Energy range: 0.045 – 2.8 GeV (p) 0.023 – 2.3 GeV (d) Max. momentum ~ 3.7 GeV/c Energy variation (ramping mode) Electron and Stochastic cooling Internal and external beams High polarization (p,d) Spin manipulation Hadronic probes: protons, deuterons Polarization: beam and targets COSY (COoler SYnchrotron) at Jülich (Germany) Introduction: COSY storage ring

5 ANKE TOF WASA Introduction: COSY overview Hadron physics with hadronic probes Experimental set-ups: ANKE WASA EDM (BNL/JEDI) PAX TOF (ext.) PAX EDM … the machine for hadron spin physics

6 PIT ANKE STT Apparatus: ANKE spectrometer Main features: Excellent Kaon identification (Positive and Negative) Low energy proton (spectator) detection (STT) Di-proton ({pp} s ) selection (by FD) Polarized (unpolarized) dense targets Main features: Excellent Kaon identification (Positive and Negative) Low energy proton (spectator) detection (STT) Di-proton ({pp} s ) selection (by FD) Polarized (unpolarized) dense targets S. Barsov et al., NIM A 462, 364 (1997)

7 Polarized Internal Target (PIT): Polarised H (D) gas (ABS) in the cell Q y = 0, -1, +1, high degree >90% Density 10 13 cm -2 Storage cell: 20 x 15 x 390 mm 3 Lamb-shift Polarimeter Polarized Internal Target (PIT): Polarised H (D) gas (ABS) in the cell Q y = 0, -1, +1, high degree >90% Density 10 13 cm -2 Storage cell: 20 x 15 x 390 mm 3 Lamb-shift Polarimeter Apparatus: PIT at ANKE COSY beam M. Mikirtychiants et al., NIM A 721, 83 (2013)

8 Description of nucleon-nucleon interaction requires precise data for Phase Shift Analysis (PSA) COSY-EDDA collaboration produced wealth of data (35°<θ p <90°) for pp elastic scattering Large impact on PSA > 0.5 GeV: Significantly reduced ambiguities in I=1 phase shifts No exp. data at smaller angles (θ p <35°) above T p =1.0 GeV A y (pp) d /d (pp) ANKE EDDA NN scattering: Motivation (pp) F. Bauer et al., PRL 90, 142301 (2003) M. Altmeier et al., PRL 85, 1819 (2000)

9 R. Arndt: Gross misconception within the community that np amplitudes are known up to a couple of GeV. np data above 800 MeV is a DESERT for experimentalists. A yy (np) d /d (np) ANKE np forward np charge-exchange ANKE np forward np charge-exchange ANKE is able to provide the experimental data for both: pp and np systems and improve our understanding of NN interaction NN scattering: Motivation (np)

10 dp observables: d /d, T 20, T 22, C N,N np observables: A y, A yy, C yy, C xy,y quasi-free dp{pp} S (0 0 )+n pd{pp} S (180 0 )+n p n d n p p sp p D deuteron beam: deuteron target: np system: different isospin channel via Charge-Exchange deuteron breakup: NN scattering: Measurements at ANKE E pp < 3 MeV, {pp} s Transition from d (pp) 1 S 0 : pn np spin flip np spin-dependent ampl.s: 2222 2220,,,, TT dq d

11 dσ/dΩ at 8 beam energies: Tp = 1.0, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8 Precision measurements: Luminosity by Schottky technique ~ 2% Absolute cross section ~ 5% Details: Stein et al., PR ST-AB 11, (2008) T p = 1.0 GeV T p = 2.0 GeV T p = 2.8 GeV SAID ANKE Preliminary SAID ANKE NN scattering: pp elastic

12 ANKE exp., April 2013, on-line (fast) analysis Ay for pp elastic (ANKE) at 6 beam energies: T p = 0.8, 1.6, 1.8, 2.0, 2.2, 2.4 FD and STT detection system is used; Analysis in progress... Beam polarization from EDDA 50 to 65% ( Preliminary ) SAID ANKE NN scattering: pp elastic (A y ) ANKE data shows different shape compared with SAID predictions at higher energies ! T p = 0.8 GeV T p = 2.0 GeV Preliminary SAID ANKE + ANKE SAID ANKE + ANKE

13 A xx (T 22 ) T d = 1.2 GeV A yy (T 20 ) T n = 600 MeV SAID np amplitudes Di-proton program: {pp} in 1 S 0 state Deuteron breakup: dp {pp} s n (polarized beam) np-data at T d = 1.2 GeV: Proof of method ! theory: Impulse approximation with current SAID input [DB&CW, NPA 467, 575, (1987)] Achievements: Method works at T d = 1.2 GeV Application to higher energies T d =1.6, 1.8, 2.27 GeV (for an angular range up to θ c.m. < 35 0 ) NN scattering: np system D.Chiladze et al. EPJA 40, 23 (2009) Goal: deduce the energy dependence of the spin-dependent np-elastic amplitudes

14 T d = 1.6 GeV (800 MeV/A) T d = 1.8 GeV (900 MeV/A) T d = 2.27 GeV (1135 MeV/A) reduced by 25% NN scattering: np system (dσ/dq, A ii ) D.Mchedlish. et al., EPJA 49, 49 (2013) SAID ANKE dp {pp} s n

15 Di-proton system, E pp < 3 MeV New: measurements for C x,x and C y,y dp {pp} s n T d = 1.2 GeV T d = 2.27 GeV T d = 1.2 GeV T d = 2.27 GeV Problem with reduced by 25% NN scattering: np system (A y, C i,i ) D.Mchedlish. et al., EPJ A 49, 49 (2013) Challenge: put info (about np spin-dependent amplitudes) into the SAID program !

16 0 n D. Mchedlishvili et al., arXiv:nucl-ex/1305.54 n 0 Di-proton program: {pp} in 1 S 0 state (E pp < 3 MeV) deuteron breakup: dp {pp} s 0 (polarized) spin transfer in the process: np p 0 first measurement (at 2.3 GeV) ! significant differences ( 0 and n): - relative sign of A´s interchanged - A´s ~ 0 for low momentum transfer T d = 2.3 GeV dp {pp} s +X NN scattering: np with Δ-isobar

17 T d = 1.6 GeV T d = 1.8 GeV T d = 2.27 GeV Direct mechanism: isobar direct production by the one pion exchange Exchange mechanism: isobar excites inside the projectile deuteron 1.Pion-nucleon are from different vertices 2.I=1/2 and I=3/2 both are allowed NN scattering: np pΔ 0 channel Mchedlishvili et al., arXiv:nucl-ex/1305.54 Direct one-pion-exchange model for np p 0 works fine for high Mx; Search for other mechanisms that might dominate near N thresh.; Further theory work is needed ! dp {pp} s +X

18 high mass region: 1.19 < M X < 1.35 GeV/c 2 Differences: Signs are flipped for all T d A xx and A yy are small at q t =0 Data will provide further impetus to the construction of more refined npp 0 models ! next step: pd {pp} s X measur. at higher proton energies dp{pp} s n at T d = 1.2 GeV dp{pp} s 0 COMPARE ! NN scattering: np pΔ 0 channel

19 Extension of ChPT to the NNNNπ process A full data set of all observables in pp {pp} s 0 and np {pp} s Extract the relevant PW amplitudes and test the ChPT predictions ( is in a p-wave, initial & final NN-pairs in S-wave, di-proton {pp} s in 1 S 0 state) pp {pp} s 0 includes 3 P 0 1 S 0 s, 3 P 2 1 S 0 d and 3 F 2 1 S 0 d np {pp} s adds 3 S 1 1 S 0 p and 3 D 1 1 S 0 p p-wave amp.s (M p S, M p D ) give access to the 4Nπ contact operator, controlled by the Low Energy Constant (LEC) d 3N scattering NN NN LEC d connects different low-energy reactions: ppde + ν, pdpd, γdnnπ + Final goal is to establish that the same LEC controls NNNNπ ! Pion production: Physics case V. Baru et al., PRC 85, (2009) A. Filin et al., PLB 681, (2009)

20 dσ/dΩ and A y in pp{pp} s π 0 Near threshold at Tp=353 MeV Pion production: π 0 channel D. Tsirkov et al., PLB 712, 370 (2012) A y is large due to s-d interference ! ANKE CELSIUS well represented by retaining only pion s and d waves, no evidence for high PWs; assuming coupling between NN-channels and invoking Watson theorem allows to estimate corresponding amplitudes with their phases: M s P, M d P and M d F

21 dσ/dΩ and A y in pn{pp} s π - T p =353 MeV H. Hahn et al., PRL 82 (1999) F. Duncan et al., PRL 80 (1998) Pion production: π channel S. Dymov et al., PLB 712, 375 (2012) ANKE TRIUMF both observables are described in terms of s-, p-, and d- wave pion amplitudes; an amplitude analysis of the combined data sets allowed to obtain: M s P, M d P, M d F, M p S, M p D --- best fit global fit

22 A x,z measurement in: pp{pp} s π 0 will test the PWA assumptions pn{pp} s π - will choose between the solutions All Observables in np{pp} s π - (ANKE data) Pion production: π channel S. Dymov et al, Acc. in PRC, arXiv:nucl-ex/1304.36 A x,x and A y,y in np{pp} s π - (T p =353 MeV) A y,y 1 conservation laws Data will allow a robust PW decomposition for both channels and determine relevant pion p -wave production strength making contact with ChPT theory ! 1 2 3

23 pp pK + Λ pp pK + Σ 0 without FSI (....) with Yp FSI ( ) T. Roźek et al., PLB 643, 251 (2006) Importance of Final State Interaction of p system Incoherent sum of 3 S 1 and 1 S 0 FSI with unknown relative strengths Spin dependence of FSI is unknown leaves too much ambiguity in the theor. modeling No direct measurements exist ! Strangeness: YN interaction p p K + Y N (mostly COSY data)

24 Separation of spin-singlet (a s ) and triplet (a t ) Λp production amplitudes and final state interactions through the measurement of: pp K + (Λp) spin correlation C NN Separation of spin-singlet (a s ) and triplet (a t ) Λp production amplitudes and final state interactions through the measurement of: pp K + (Λp) spin correlation C NN Strangeness: Spin-singlet/triplet Λp interaction Experimental information: Some data on low energy (spin-averaged) Λp total elastic cross sections; Binding energies of hypernuclei suggest spin singlet force a s is more attractive than a t ; Λp FSI in K - d π (Λp) is sensitive to S-wave spin-triplet; FSI of pp K + (Λp) is unknown mixture of a s and a t ; Precise (inclusive) measurements carried out at SATURNE and HIRES/COSY; HIRES: global fit of all relevant data gave best fit with purely singlet (Λp) amplitude Better to measure in a single experiment ! COSY proposal #219 (2013)

25 Strangeness: Spin-singlet/triplet Λp interaction Further information: COSY-TOF has clearly shown dominance of N* prodiction in pp K + (Λp): suggests S-wave final state dominance; In the near-threshold region there are two pp K + (Λp) final S-wave production amplitudes: Μ 1 = [ W 1,s η f p ε i + i W 1,t p (ε i X ε f )] f i The unpolarized cross section is proportional to: I ( pp K + Λp) = ¼ (| W 1,s | 2 + 2 |W 1,t | 2 ) The spin-correlation picks out purely the singlet: I ( pp K + Λp) C NN ( pp K + Λp) = ¼ | W 1,s | 2 The ratio of spin-triplet to spin-singlet production is fixed completely by spin-correlation: [ 1 - C NN ( pp K + Λp) ] / 2C NN = | W 1,t | 2 / | W 1,s | 2 The first aim of exp.: what fraction of the production is associated with spin-singlet and triplet (Λp) ? There will be a tremendous enhancement near Λp threshold due to very strong FSI ! S. Abd El-Samad et al., PLB 688, 142 (2010) G. Fäldt and C. Wilkin, EPJ A 24, 431 (2005) A.Gasparyan et al., PRC 69, 034006 (2004)

26 Strangeness: Spin dependence of the p force Each of the W 1,t and W 1,s will have own FSI factor, depending on spin-triplet/singlet scattering lenghts ; We want to measure C NN as a function of the kaon momentum in the region of Λp final state interaction peak; Simple π + ρ exchange model near threshold suggests that singlet production is 5 times stronger than triplet will give globally C NN 0.84. ANKE has considarable experience in detecting K + p correlations and able to measure such an observable ! G. Fäldt and C. Wilkin, EPJ A 24, 431 (2005 ) HIRES/COSY …. phase-space combined fit …. spin aver. par. combined fit PLB 687, 31 (2010)

27 Double polarization: (i) pn np (spin observables) (ii) np {pp} s - (A xz parameter) (iii) pp K + p (C NN coefficient) All experiments are approved and scheduled for 2013/14 ! Future measurements: ANKE experiments

28 COSY - unique opportunities for hadron physics with polarized hadronic probes (beam & target) – High precision + Spin ANKE state-of-the art facility to investigate a broad and exciting field of physics Physics: NN interaction, ChPT, FSI – selected examples and further plans at ANKE New opportunities to explore longitudinal polarization using Siberian Snake at COSY Summary

29 The END Many thanks to the conference organizers !

30 Spare slides

31 Strangeness: K + K - pair production at ANKE Q.I. Ye et al., PRC 87, 065303 (2013) Production of kaon pairs below the and above φ-threshold can be understood in terms of pp & Kp FSI The shapes of Kp and Kpp invariant masses are strongly influenced by the K - p interaction ! R Kp shows preference for low values of M Kp It has been suggested (CW) this may connected with the production of the excited hyperon assuming the decay N* K + The strength of the KN intercation important element in the iterpretation of possible kaon nuclear systems, such as deeply bound K - pp states. pp ppK + K - K+p K+p K + pp Y. Maeda et al., PRC 77, 015294 (2008 ) C. Wilkin, Acta. Phys. Polon. Suppl. 2, 89 (2009) K-p K-p K - pp R Kp R Kpp

32 Physics at COSY using longitudinally polarized beams: Snake Concept Should allow for flexible use at two locations Fast ramping (< 30s) Cryogen-free system B dl (Tm) pn{pp} s π - at 353 MeV3.329 PAX at COSY 140 MeV1.994 BUP at COSY 30-50 MeV1.165 T max at COSY 2.88 GeV13.887 ANKE-location 180 o EDDA PAX-location

33 ANKE Silicon Tracking Telescopes:


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