Quasi-free Cross Section Measurements at CLAS: D p - (p) D K + - PowerPoint PPT Presentation

Quasi-free Cross Section Measurements at CLAS: γ D à p π - (p) γ D à K + Σ *(1385) - (p) γ D à K*(892) 0 Λ (p) Paul Mattione, Carnegie Mellon University for the CLAS Collaboration supported by the DOE Office of Science Hadron 2013 November 5, 2013

2 Outline Introduction to N*’s × CLAS g13 experiment & analysis × Differential cross section measurements × γ D à p π - (p) × γ D à K*(892) 0 Λ (p) & γ D à K + Σ *(1385) - (p) × Comparison to ground state γ p à K + Λ & γ D à K + Σ - (p) × Summary & conclusions × Hadron 2013 Paul Mattione, Carnegie Mellon University November 5, 2013

3 Introduction to N*’s Hadron 2013 Paul Mattione, Carnegie Mellon University November 5, 2013

4 N* Resonance Spectrum (2012) Predicted N* spectrum × (Capstick, Isgur) [1] Quark model × PDG [3] changes since 2010: × 4 new PDG resonances × (vertical bars) 2 states upgraded to ***: × N(1900)[3/2] + , N(1875)[3/2] - Most searches: × Proton targets, non-strange × channels (e.g. π N) Legend Black: “Established” (4*, 3*) [3] Blue: Inconclusive (2*, 1*) [3] Red: Unobserved [3] [1, 2, 3] Hadron 2013 Paul Mattione, Carnegie Mellon University November 5, 2013

5 Searching for N* Resonances “Missing” N* resonances [1] × Wide, overlapping × Correlated quark-pair? [4] × N* decays: KY, K*Y , KY* × Couplings sizable vs. N π [3] × Sparse γ n data vs. γ p × Amplitudes (isospin) × No known γ n à K*(892) 0 Λ × cross section measurements Legend Black: “Established” (4*, 3*) [3] Blue: Inconclusive (2*, 1*) [3] Red: Unobserved [3] Cyan: γ N à à K*(892) Λ [5] [1, 2, 3] Hadron 2013 Paul Mattione, Carnegie Mellon University November 5, 2013

6 Searching for N* Resonances “Missing” N* resonances [1] × Wide, overlapping × Correlated quark-pair? [4] × N* decays: KY, K*Y , KY* × Couplings sizable vs. N π [3] × Sparse γ n data vs. γ p × Amplitudes (isospin) × LEPS γ n à K + Σ *(1385) - data × limited to low- θ [6] Legend Black: “Established” (4*, 3*) [3] Blue: Inconclusive (2*, 1*) [3] Red: Unobserved [3] Violet: γ N à à K Σ *(1385) [5] [1, 2, 3] Hadron 2013 Paul Mattione, Carnegie Mellon University November 5, 2013

7 CLAS g13 Experiment and Analysis Hadron 2013 Paul Mattione, Carnegie Mellon University November 5, 2013

JLab: CEBAF, CLAS, & g13 8 JLab CEBAF accelerator: up to 6 GeV e - [7] CLAS [8] × CLAS detector (Hall B) [8] × DC: Tracking, TOF: Timing × g13 experiment: 10/06 – 06/07, LD 2 target × → Analysis: E e- = 2.655 GeV, circularly × polarized γ ’s γ beam: radiator, γ tagger detects e - [9] × CEBAF [7] γ Tagger [9] Hadron 2013 Paul Mattione, Carnegie Mellon University November 5, 2013

9 Event Selection γ D à K*(892) 0 Λ (p) & γ D à K + Σ *(1385) - (p) × Final state: K + , π - , p , π - , (p) × Cuts: Λ , (p) masses × γ D à p π - (p): Cut on (p) mass × All: Select quasi-free events: × Cut missing momentum > 200 MeV/c × Still large rescattering effects for E γ > 1 GeV, θ < ~ 15° - 30° [10] × Λ (p) Hadron 2013 Paul Mattione, Carnegie Mellon University November 5, 2013

10 Dalitz Plots Yield: ~17000 K*(892) 0 Λ events, ~100000 K+ Σ *(1385) - events × K*(892) 0 à K+ π - Color scale changes with row Cut Σ * - in K* 0 analysis (dominates) Don’t cut K* 0 in Σ * - analysis: - Potential interference < systematics Σ *(1385) - à Λπ - Hadron 2013 Paul Mattione, Carnegie Mellon University November 5, 2013

11 Differential Cross Section Measurements Hadron 2013 Paul Mattione, Carnegie Mellon University November 5, 2013

γ D à p π - (p) Cross Section 12 CLAS g13: Preliminary, high statistics: ~300 million events in ~9000 bins: × 10- & 20-MeV-wide bins from 0.56 < E γ (GeV) < 2.52 × Significant increase in statistics: CLAS g10 [11] had ~3000 bins × Compared to CLAS g10 [11] , SAID CM12 [12] , BnGa12-1 [13] × Statistical uncertainties only (g10 pre-FSI correction) × Legend Black: CLAS g13 Red: CLAS g10 [11] Blue: SAID CM12 [12] Green: BnGa12-1 [13] Hadron 2013 Paul Mattione, Carnegie Mellon University November 5, 2013

γ D à p π - (p) Cross Section 13 Overall good matching between g10 & g13, need more acceptance studies × Data will improve: × Understanding of N* couplings to neutron in π N × Understanding of rescattering: working with Igor Strakovsky (GWU) × Legend Black: CLAS g13 Red: CLAS g10 [11] Blue: SAID CM12 [12] Green: BnGa12-1 [13] Hadron 2013 Paul Mattione, Carnegie Mellon University November 5, 2013

14 γ D à K + Σ *(1385) - (p) Cross Section Data: LEPS [6] , Preliminary CLAS g13, Oh et. al model [14] : × CLAS g13: ~100000 events, no systematic errors, ~ -0.5 < cos( θ ) < 0.75 × Oh, et. al model: Effective Lagrangians × Dominated by t-channel K + and K* + , some N*’s and Δ *’s included × Legend Black: CLAS g13 (preliminary) Red: LEPS [6] Blue: Oh, et. al Model [14] Hadron 2013 Paul Mattione, Carnegie Mellon University November 5, 2013

15 γ D à K + Σ *(1385) - (p) Cross Section t-channel dominated × g13 & LEPS close, model significantly lower × Disagreement with prediction: perhaps t-channel modeling × Legend Black: CLAS g13 (preliminary) Red: LEPS [6] Blue: Oh, et. al Model [14] Hadron 2013 Paul Mattione, Carnegie Mellon University November 5, 2013

16 γ D à K*(892) 0 Λ (p) Cross Section Data: Preliminary CLAS g13 (~12000 events, no systematic errors) × S.-H. Kim, et. al model [15] : Effective Lagrangians × K 0 t-channel exchange dominates, N[3/2-](2080) is dominant N* × Legend Black: CLAS g13 Red: Kim et. al w. N*’s [15] Blue: Kim et. al w/o N*’s [15] Hadron 2013 Paul Mattione, Carnegie Mellon University November 5, 2013

17 γ D à K*(892) 0 Λ (p) Cross Section t-channel dominated × Disagreement with prediction: perhaps t-channel modeling × Possible small K*(892) 0 Σ 0 background leakage, need to investigate × Legend Black: CLAS g13 Red: Kim et. al w. N*’s [15] Blue: Kim et. al w/o N*’s [15] Hadron 2013 Paul Mattione, Carnegie Mellon University November 5, 2013

γ D à K*(892) 0 Λ (p) vs. γ p à K + Λ 18 ~Comparison vs. ground state [16] ( γ D à K 0 Λ (p) being analyzed): × Similar at Mid- θ × Rescattering through π N: ~20% effect on K Λ [17] × K* Λ sizable vs. K Λ : N* coupled-channels analyses × Legend Black: g13 γ D à K*(892) 0 Λ (p) Red: CLAS g11 γ p à K + Λ [16] Hadron 2013 Paul Mattione, Carnegie Mellon University November 5, 2013

19 γ D à K + Σ *(1385) - (p) vs. γ D à K + Σ - (p) Scale comparison vs. ground state × Similar scale in most regions × K Σ *(1385): N* coupled-channels analyses × Legend Black: g13 γ D à K + Σ *(1385) - (p) Red: LEPS γ n à K + Σ *(1385) - [6] Blue: CLAS g10 γ n à K + Σ - [18] Hadron 2013 Paul Mattione, Carnegie Mellon University November 5, 2013

20 Summary & Conclusions Hadron 2013 Paul Mattione, Carnegie Mellon University November 5, 2013

21 Summary & Conclusions N* spectrum: Strong force and hadronic structure × Role of quark correlations: limit N* spectrum × Search in KY, K*Y, and KY* channels × Preliminary quasi-free cross sections: × γ D à p π - (p), γ D à K*(892) 0 Λ (p), & γ D à K + Σ *(1385) - (p) × N* couplings, greater understanding of interactions × High-statistics γ D à p π - (p) data: study rescattering × K*Y & KY* sizable vs. KY: include in coupled-channels analyses × These results will be published after systematic studies are × performed, and will contribute to the search for the N* resonances. Hadron 2013 Paul Mattione, Carnegie Mellon University November 5, 2013

22 References [1] S. Capstick and N. Isgur, Phys. Rev. D 34 , 2809 (1986). [2] W. Roberts, http://www.physics.fsu.edu/users/roberts/roberts_hadrons.html [3] K. Nakamura et al. (The Particle Data Group), J. Phys. G 37 , 075021 (2010). [4] E. Santopinto, Phys. Rev. C 72 , 022201(R) (2005). [5] S. Capstick and W. Roberts, Phys. Rev. D 58 , 074011 (1998). [6] K. Hicks et al. (The LEPS Collaboration), arXiv:0812.0771 [nucl-ex] (2008). [7] C. W. Leemann, D.R. Douglas, G.A. Krafft, Annu. Rev. Nucl. Part. Sci. 51 , 413 (2001). [8] B. A. Mecking et al. (The CLAS Collaboration), Nucl. Instr. and Meth. A 503 , 513 (2003). [9] D. I. Sober et al. (The CLAS Collaboration), Nucl. Instr. and Meth. A 440 , 263 (2000). [10] V. E. Tarasov et al. , Phys. Rev. C 84 , 035203 (2011). [11] W. Chen et al. (The CLAS Collaboration), Phys. Rev. Lett. 103, 012301 (2009). [12] CNS DAC Services (SAID Program), http://gwdac.phys.gwu.edu/ [13] Bonn Gatchina Partial Wave Analysis, http://pwa.hiskp.uni-bonn.de/ [14] Y. Oh, C. M. Ko, K. Nakayama, Phys. Rev. C 77 , 045204 (2008). [15] S.-H. Kim, S.-i. Nam, Y. Oh, H.-C. Kim, Phys. Rev. D 84 , 114023 (2011). [16] M. E. McCracken et al . (The CLAS Collaboration), Phys. Rev. C 81 , 025201 (2010). [17] W-T. Chiang, F. Tabakin, T.-S. H. Lee, and B. Saghai, Phys. Lett. B 517 , 101 (2001). [18] S. Anefalos Pereira et al. (The CLAS Collaboration), Phys. Lett. B 688 , 289 (2010). Hadron 2013 Paul Mattione, Carnegie Mellon University November 5, 2013