1. First Measurement of the Beam Normal Single Spin Asymmetry in Δ Resonance Production by Q-weak Nuruzzaman (https://userweb.jlab.org/~nur/)https://userweb.jlab.org/~nur/ for the Q-weak Collaboration

2. Outline CIPANP 2015 Nuruzzaman 2  Beam Normal Single Spin Asymmetry  Experimental apparatus  Overview of the dataset  Overview of analysis and preliminary result  Comparison with a theory calculation

3. Beam Normal Single Spin Asymmetry CIPANP 2015 Nuruzzaman 3 B n = σ − σ σ + σ Beam Normal Single Spin Asymmetries (B n ) are generated when transversely polarized electrons scatter from unpolarized targets B n is parity conserving and is time-reversal invariant spin UP spin DOWN

4. Beam Normal Single Spin Asymmetry CIPANP 2015 Nuruzzaman 3 B n = 2T 1 γ × Im T 2 γ |T 1 γ | σ − σ σ + σ = γ + γγ Beam Normal Single Spin Asymmetries (B n ) are generated when transversely polarized electrons scatter from unpolarized targets B n is parity conserving and is time-reversal invariant B n provides direct access to the imaginary part of the two-photon exchange amplitude B n arises from the interference of 2-photon exchange with 1-photon exchange in e-N scattering T 1 γ – amplitude for 1-photon exchange T 2 γ – amplitude for 2-photon exchange spin UP spin DOWN

5. Beam Normal Single Spin Asymmetry CIPANP 2015 Nuruzzaman 3 B n = 2T 1 γ × Im T 2 γ |T 1 γ | σ − σ σ + σ = T 1 γ – amplitude for 1-photon exchange T 2 γ – amplitude for 2-photon exchange Contains information about the Intermediate states of the nucleon γ + γγ Beam Normal Single Spin Asymmetries (B n ) are generated when transversely polarized electrons scatter from unpolarized targets B n is parity conserving and is time-reversal invariant B n provides direct access to the imaginary part of the two-photon exchange amplitude B n arises from the interference of 2-photon exchange with 1-photon exchange in e-N scattering spin UP spin DOWN

6. B n in the Production of the Δ Resonance CIPANP 2015 Nuruzzaman 4 Measuring B n in e + p e + Δ

7. B n in the Production of the Δ Resonance CIPANP 2015 Nuruzzaman 4 Proton EM FF well known. N→Δ EM transition FF fairly well known Unique tool to study  *ΔΔ form factors Potential to constrain charge radius and magnetic moment of Δ ! Physics Motivation: For p and Δ intermediate hadrons, vertices are known - except for  *ΔΔ electromagnetic (EM) vertex Measuring B n in e + p e + Δ More details by M. Dalton on Wed

8. Asymmetry Measurement CIPANP 2015 Nuruzzaman 5 Measured asymmetry M ( ϕ ) = N − N N + N e-e- proton θ K K'K' Detector S S B n is also known as transverse asymmetry Can be measured with a transversely polarized beam to determine the magnitude

9. Asymmetry Measurement CIPANP 2015 Nuruzzaman 5 Measured asymmetry M ( ϕ ) = N − N N + N = − B n S.n = B n S sin( ϕ - ϕ 0 ) = B n [P V cos( ϕ ) - P H sin( ϕ )] ∧ n = ∧ k × k’ |k × k’| Measured asymmetry has a small azimuthal dependence e-e- proton θ K K'K' Detector S S Horizontal: P H = S cos( ϕ 0 ) Vertical: P V = S sin( ϕ 0 ) B n is also known as transverse asymmetry Can be measured with a transversely polarized beam to determine the magnitude

10. Jefferson Lab and Q-weak Setup CIPANP 2015 Nuruzzaman 6 C A B D Q-weak experiment ran in Hall-C at the Thomas Jefferson National Laboratory in Newport News, Virginia from Jan 2010 – May 2012 Q-weak setup inside Hall-C (during construction) Aerial view of Jefferson Lab Transverse measurements were taken from 16 - 20 February, 2012

11. B n Measurement Using Q-weak Apparatus CIPANP 2015 Nuruzzaman 7 E beam = 1.16 GeV ~ 8.3° Q 2 = 0.021 (GeV/c) 2 ϕ coverage ~ 49% of 2π Current = 180 μA Polarization = 88% Kinematics

12. B n Measurement Using Q-weak Apparatus CIPANP 2015 Nuruzzaman 7 E beam = 1.16 GeV ~ 8.3° Q 2 = 0.021 (GeV/c) 2 ϕ coverage ~ 49% of 2π Current = 180 μA Polarization = 88% Kinematics

13. B n Measurement Using Q-weak Apparatus CIPANP 2015 Nuruzzaman 7 3 7 51 2 4 8 6 ϕ  (octant # − 1) x 45 o E beam = 1.16 GeV ~ 8.3° Q 2 = 0.021 (GeV/c) 2 ϕ coverage ~ 49% of 2π Current = 180 μA Polarization = 88% Kinematics

14. Transverse Dataset CIPANP 2015 Nuruzzaman 8 Δ peak Simulation at E = 1.16 GeV elastic peak Toroidal magnet spectrometer current [A] Data on 3 types of targets Hydrogen Aluminum Carbon Transverse polarization: Horizontal Vertical

15. Transverse Dataset CIPANP 2015 Nuruzzaman 8 Data on 3 types of targets Hydrogen Aluminum Carbon Transverse polarization: Horizontal Vertical Δ peak This talk: Inelastic e-p scattering with a Δ(1232) final state at E = 1.16 GeV Simulation at E = 1.16 GeV elastic peak Toroidal magnet spectrometer current [A]

16. Transverse Dataset CIPANP 2015 Nuruzzaman 8 Data on both side of the inelastic peak were taken to study the elastic dilution Δ peak This talk: Inelastic e-p scattering with a Δ(1232) final state at E = 1.16 GeV Simulation at E = 1.16 GeV elastic peak Toroidal magnet spectrometer current [A] Data on 3 types of targets Hydrogen Aluminum Carbon Transverse polarization: Horizontal Vertical

17. Transverse Dataset CIPANP 2015 Nuruzzaman 8 Δ peak Other datasets: in the →Δ region (Al, C) in the →Δ region (H 2, 0.877 GeV) elastic scattering (H 2, Al, C) elastic Møller scattering (H 2 ) in the DIS region (3.3 GeV) in pion photoproduction This talk: Inelastic e-p scattering with a Δ(1232) final state at E = 1.16 GeV Simulation at E = 1.16 GeV elastic peak Data on both side of the inelastic peak were taken to study the elastic dilution Toroidal magnet spectrometer current [A] Data on 3 types of targets Hydrogen Aluminum Carbon Transverse polarization: Horizontal Vertical

18. Asymmetries from Main Detector Signals CIPANP 2015 Nuruzzaman 9 Not corrected for False beam asymmetries Polarization Backgrounds R L raw = L + R 2 ~0.6 V Right PMT Left PMT e-e- Integrating signal

19. Correction for False Beam Asymmetries CIPANP 2015 Nuruzzaman 10 Correcting for the helicity correlated changes in beam position, angle and energy using linear regression T i = X, X´, Y, Y´ & E reg = raw - ∂ raw ∂T i ∆T i ∑ i Not corrected for Polarization Backgrounds

20. Correction for False Beam Asymmetries CIPANP 2015 Nuruzzaman 10 Correcting for the helicity correlated changes in beam position, angle and energy using linear regression T i = X, X´, Y, Y´ & E reg = raw - ∂ raw ∂T i ∆T i ∑ i ∆X ∂ raw ∂X Not corrected for Polarization Backgrounds 0° 45° 90° 135° 180° 225° 270° 315° example: ~2hr measurement

21. Correction for False Beam Asymmetries CIPANP 2015 Nuruzzaman 10 Correcting for the helicity correlated changes in beam position, angle and energy using linear regression reg = raw - ∂ raw ∂T i ∆T i ∑ i Not corrected for Polarization Backgrounds Small corrections (<1%), compared to the size of the asymmetry example: ~2hr measurement

22. Regressed Transverse Asymmetries 11 Nuruzzaman CIPANP 2015 Fit function for horizontal: reg H sin( ϕ )  Regressed asymmetries  Not corrected for polarization and backgrounds 0° 45° 90° 135° 180° 225° 270° 315°

23. Regressed Transverse Asymmetries 11 Nuruzzaman CIPANP 2015 Fit function for horizontal: reg H sin( ϕ ) vertical: reg V cos( ϕ ) ~90 o phase offset  Regressed asymmetries  Not corrected for polarization and backgrounds 0° 45° 90° 135° 180° 225° 270° 315°

24. Regressed Transverse Asymmetries 12 Nuruzzaman CIPANP 2015 reg = 5.1 ± 0.4 (stat) ppm Measured asymmetry  Error weighted (H and V) regressed asym.  Corrected for detector acceptance  Not corrected for polarization and backgrounds

25. Summary of Uncertainties on reg 13 Nuruzzaman CIPANP 2015 dominated by statistics systematics are under control  Error weighted (H and V) regressed asym.  Corrected for detector acceptance  Not corrected for polarization and backgrounds reg = 5.1 ± 0.4 (stat) ± 0.1 (sys) ppm Measured asymmetry

26. Extraction of Physics Asymmetry 14 Nuruzzaman CIPANP 2015 Beam Normal Single Spin Asymmetry

27. Extraction of Physics Asymmetry 14 Nuruzzaman CIPANP 2015 Beam Normal Single Spin Asymmetry Extracting B n from the experimental measured asymmetry by  removing false asymmetries  reg = raw - ∂ raw ∂T i ∆T i, cor. for det. acpt. ∑ i

28. Extraction of Physics Asymmetry 14 Nuruzzaman CIPANP 2015 Beam Normal Single Spin Asymmetry Extracting B n from the experimental measured asymmetry by  removing false asymmetries  correcting for the beam polarization  reg = raw - ∂ raw ∂T i ∆T i, cor. for det. acpt. ∑ i

29. Extraction of Physics Asymmetry 14 Nuruzzaman CIPANP 2015 Beam Normal Single Spin Asymmetry Extracting B n from the experimental measured asymmetry by  removing false asymmetries  correcting for the beam polarization  removing background asymmetries B bi = Background asymmetries f bi = dilution factors   reg = raw - ∂ raw ∂T i ∆T i, cor. for det. acpt. ∑ i Al : aluminum window backgrounds BB : scattering from the beamline QTor: neutral particles in the magnet acpt. el : elastic radiative tail

30. Extraction of Physics Asymmetry 14 Nuruzzaman CIPANP 2015 Beam Normal Single Spin Asymmetry Extracting B n from the experimental measured asymmetry by  removing false asymmetries  correcting for the beam polarization  removing background asymmetries  correcting for radiative tails and other kinematic correction Al : aluminum window backgrounds BB : scattering from the beamline QTor: neutral particles in the magnet acpt. el : elastic radiative tail B bi = Background asymmetries f bi = dilution factors   M kin = kinematic correction  reg = raw - ∂ raw ∂T i ∆T i, cor. for det. acpt. ∑ i

31. Extraction of Physics Asymmetry and Uncertainties 15 Nuruzzaman CIPANP 2015 Beam Normal Single Spin Asymmetry at kinematics = 1.16 GeV = 1.2 GeV = 8.3° = 0.021 GeV 2 ~ 38% measurement of beam normal single asymmetry in Δ resonance production B n = 43 ± 16 ppm Preliminary

32. Summary of Uncertainties 16 Nuruzzaman CIPANP 2015 Beam Normal Single Spin Asymmetry Summary of Uncertainties B n = 43 ± 16 ppm Preliminary

33. Summary of Uncertainties 16 Nuruzzaman CIPANP 2015 Beam Normal Single Spin Asymmetry B n = 43 ± 16 ppm Summary of Uncertainties Preliminary

34. Summary of Uncertainties 16 Nuruzzaman CIPANP 2015 Beam Normal Single Spin Asymmetry B n = 43 ± 16 ppm Summary of Uncertainties Preliminary

35. Summary of Uncertainties 16 Nuruzzaman CIPANP 2015 Beam Normal Single Spin Asymmetry B n = 43 ± 16 ppm Summary of Uncertainties Preliminary

36. Summary of Uncertainties 16 Nuruzzaman CIPANP 2015 Beam Normal Single Spin Asymmetry B n = 43 ± 16 ppm Summary of Uncertainties Preliminary

37. Summary of Uncertainties 16 Nuruzzaman CIPANP 2015 Beam Normal Single Spin Asymmetry Biggest contribution is from elastic radiative tail B n = 43 ± 16 ppm Summary of Uncertainties Preliminary

38. Elastic Radiative Tail CIPANP 2015 Nuruzzaman 17 Preliminary BNSSA in elastic e-p scattering using Q-weak apparatus is B n el = -5.35 ± 0.07 (stat) ± 0.15 (sys) ppm at kinematics = 1.16 GeV = 7.9° = 0.025 GeV 2 Background Corrections Elastic radiative tail Beam Normal Single Spin Asymmetry At similar kinematics reg in has opposite sign to the reg el B n in is much larger than the absolute value B n el Asymmetry

39. Elastic Radiative Tail CIPANP 2015 Nuruzzaman 17 B el = -5.1 ± 0.5 ppm  Scaled elastic asym. (B n el ~√Q 2 ) to inelastic kinematics, additional 10% uncertainty for scaling Preliminary BNSSA in elastic e-p scattering using Q-weak apparatus is B n el = -5.35 ± 0.07 (stat) ± 0.15 (sys) ppm at kinematics = 1.16 GeV = 7.9° = 0.025 GeV 2 Background Corrections Elastic radiative tail Beam Normal Single Spin Asymmetry At similar kinematics reg in has opposite sign to the reg el B n in is much larger than the absolute value B n el Asymmetry Background asymmetry from elastics

40. Elastic Radiative Tail CIPANP 2015 Nuruzzaman 18 Background Corrections Elastic radiative tail Beam Normal Single Spin Asymmetry Δ peak B el = -5.1 ± 0.5 ppm Dilution elastic peak Toroidal magnet spectrometer current [A]

41. Elastic Radiative Tail CIPANP 2015 Nuruzzaman 18 f el = 0.70 ± 0.07 Background Corrections Elastic radiative tail Beam Normal Single Spin Asymmetry This prelim. analysis takes10% additional uncertainty due to discrepancy between data and simulation (incomplete) Residual = (data – sim.) data B el = -5.1 ± 0.5 ppm Dilution elastic peak Δ peak elastic peak Δ peak Toroidal magnet spectrometer current [A]

42. Asymmetry is Diluted by Elastic Radiative Tail CIPANP 2015 Nuruzzaman 19 Simplifying* the extraction equation (* for illustrative purposes) 0.214×43 ppm = 9.2 ppm ≈ (5.1/0.875) - 0.70×(-5.1) - 0.3 = 5.8 - (-3.6) - 0.3 ppm

43. Asymmetry is Diluted by Elastic Radiative Tail CIPANP 2015 Nuruzzaman 19 Simplifying* the extraction equation (* for illustrative purposes) 0.214×43 ppm = 9.2 ppm ≈ (5.1/0.875) - 0.70×(-5.1) - 0.3 = 5.8 - (-3.6) - 0.3 ppm

44. Asymmetry is Diluted by Elastic Radiative Tail CIPANP 2015 Nuruzzaman 19 Plot to illustrate the dependence of B n on f el Simplifying* the extraction equation (* for illustrative purposes) 0.214×43 ppm = 9.2 ppm ≈ (5.1/0.875) - 0.70×(-5.1) - 0.3 = 5.8 - (-3.6) - 0.3 ppm

45. Asymmetry is Diluted by Elastic Radiative Tail CIPANP 2015 Nuruzzaman 19 The extraction of B n depends strongly on the elastic dilution Careful study is ongoing to reduce uncertainty in f el Plot to illustrate the dependence of B n on f el Simplifying* the extraction equation (* for illustrative purposes) 0.214×43 ppm = 9.2 ppm ≈ (5.1/0.875) - 0.70×(-5.1) - 0.3 = 5.8 - (-3.6) - 0.3 ppm

46. Comparison of B n to Theory Calculation 20 Nuruzzaman CIPANP 2015 sensitive to γ *ΔΔ form factors In the calculation there is lattice QCD parameterizations for γ *ΔΔ form factors which are not so well known large asymmetries in the forward region

47. Comparison of B n to Theory Calculation 20 Nuruzzaman CIPANP 2015 sensitive to γ *ΔΔ form factors Q-weak transverse dataset along with world data has potential to constrain models and study charge radius and magnetic moment of Δ Measured B n agrees with theoretical calculation

48. 0° 45° 90° 135° 180° 225° 270° 315° Summary CIPANP 2015 Nuruzzaman 21 Q-weak has measured B n in the N-to-Δ transition on H 2 43 ± 16 ppm = 1.16 GeV, = 1.2 GeV, = 8.3°, = 0.021 GeV 2 preliminary result shows agreement with a theoretical calculation physics implications of the model needs investigation sensitive to γ *ΔΔ form factors working towards the improvement in systematic uncertainty Data for B n at low Q 2 in elastic and inelastic scattering with a Δ(1232) final state from several targets and energy are available. looking for model predictions ! Q-weak transverse dataset along with world data has potential to constrain models and study charge radius and magnetic moment of Δ Δ peak Toroidal magnet spectrometer current [A] elastic peak

49. Acknowledgement CIPANP 2015 Nuruzzaman 22 Q-weak Collaboration Special thanks to Babara Pasquini for providing theory predictions at Q-weak kinematics D.S. Armstrong, A. Asaturyan, T. Averett, J. Balewski, J. Beaufait, R.S. Beminiwattha, J. Benesch, F. Benmokhtar, J. Birchall, R.D. Carlini 1, J.C. Cornejo, S. Covrig, M.M. Dalton, C.A. Davis, W. Deconinck, J. Diefenbach, K. Dow, J.F. Dowd, J.A. Dunne, D. Dutta, W.S. Duvall, M. Elaasar, W.R. Falk, J.M. Finn 1, T. Forest, D. Gaskell, M.T.W. Gericke, J. Grames, V.M. Gray, K. Grimm, F. Guo, J.R. Hoskins, K. Johnston, D. Jones, M. Jones, R. Jones, M. Kargiantoulakis, P.M. King, E. Korkmaz, S. Kowalski 1, J. Leacock, J. Leckey, A.R. Lee, J.H. Lee, L. Lee, S. MacEwan, D. Mack, J.A. Magee, R. Mahurin, J. Mammei, J. Martin, M.J. McHugh, J. Mei, R. Michaels, A. Micherdzinska, K.E. Myers, A. Mkrtchyan, H. Mkrtchyan, A. Narayan, L.Z. Ndukum, V. Nelyubin, Nuruzzaman, W.T.H van Oers, A.K. Opper, S.A. Page 1, J. Pan, K. Paschke, S.K. Phillips, M.L. Pitt, M. Poelker, J.F. Rajotte, W.D. Ramsay, J. Roche, B. Sawatzky,T. Seva, M.H. Shabestari, R. Silwal, N. Simicevic, G.R. Smith 2, P. Solvignon, D.T. Spayde, A. Subedi, R. Subedi, R. Suleiman, V. Tadevosyan, W.A. Tobias, V. Tvaskis, B. Waidyawansa, P. Wang, S.P. Wells, S.A. Wood, S. Yang, R.D. Young, S. Zhamkochyan 1 Spokespersons 2 Project Manager Grad Students

50. CIPANP 2015 Nuruzzaman 23 Backup Slides

51. Δ Elastic Form Factors CIPANP 2015 Nuruzzaman There are 4 elastic form factors (spin 3/2) G E0 (Q 2 ), G M1 (Q 2 ), G E2 (Q 2 ), G M3 (Q 2 ) J. Segovia et. al. arXiv:1308.5225 (2013) Q 2 = 0 define dimensionless multipole moments G E0 (0) = e Δ charge G M1 (0) ∝ μ Δ magnetic moment G E2 (0) ∝ D Δ dipole moment G M3 (0) ∝ O Δ octopole moment

52. Summary of Measurements CIPANP 2015 Nuruzzaman N + π N + 2π D 13 F 15... PVA4 Q-weak SOLID Higher beam energies allow more intermediate states

53. Two Photon Exchange CIPANP 2015 Nuruzzaman Form factors: Δ p, Δ, X p e-e- e-e- γγ p p γ Δ p γ X p γ + + + Δ p γ Δ Δ γ + + FF TFF Don’t know This measurement will help Δ p, Δ, X p e-e- e-e- γγ p(n) π0(π+)π0(π+) Don’t know X Δ γ

54. Why B n =0 at θ =0 ? CIPANP 2015 Nuruzzaman σ − σ ∝ 2m e Q εLεL ε (1-ε) = 2m e Q Q ν (1-ε) 1/2 Q ν = 2m e ν (1-ε) ν el = 0.013 ν in = 0.348 ν min = 300 MeV + K. E. Private communication with Carl Carlson (1-ε) = ε(1/ε-1) ε -1 = 1+ 2 ν2ν2 Q2Q2 1+ tan 2 θeθe 2 = 2ε ν2ν2 Q2Q2 1+ tan 2 θeθe 2 B n = 2T 1γ × Im T 2γ |T 1γ | σ − σ σ + σ = ν = K  P K is the average incoming four-momenta of the electron P is the average outgoing four-momenta of the proton = ν2ν2 Q2Q2 1+ tan 2 θeθe 2 ν 4m e ε

55. Regression Scheme Dependence CIPANP 2015 Nuruzzaman Horizontal transverse Corrections were small (0.15% <<10% stat error) Vertical transverse Corrections were small (1.7% <<18% stat error) Regression scheme dependence is ~ 0.005 ppm (0.1%) Horizontal Vertical

56. Regression Scheme Dependence CIPANP 2015 Nuruzzaman Horizontal transverse Corrections were small (0.15% <<10% stat error) Vertical transverse Corrections were small (1.7% <<18% stat error) Regression scheme dependence is ~ 0.005 ppm (0.1%)

57. Summary of Uncertainties on reg reg = 5.07 ± 0.44 (stat) ± 0.08 (sys) ppm Nuruzzaman CIPANP 2015 uncertainty is dominated by statistics All other systematics are under control corrected for detector acceptance Measured asymmetry

58. Fit Scheme Dependence CIPANP 2015 Nuruzzaman Horizontal Transverse Vertical Transverse Fit Function reg H [ppm] reg H (n) – reg H (1) [ppm] 1 reg H sin( ϕ + ϕ 0 ) + C 5.343±0.5320.000 2 reg H sin( ϕ + ϕ 0 ) 5.344±0.532+0.001 3 reg H sin( ϕ ) + C 5.303±0.533−0.040 4 reg H sin( ϕ ) 5.304±0.533−0.039 Fit Function reg V [ppm] reg V (n) – reg V (1) [ppm] 1 reg V cos ( ϕ + ϕ 0 ) + C 4.525±0.8060.000 2 reg V cos( ϕ + ϕ 0 ) 4.510±0.806−0.015 3 reg V cos ( ϕ ) + C 4.458±0.807−0.067 4 reg V cos ( ϕ ) 4.442±0.807−0.083 Small fit scheme dependence for horizontal transverse, slightly higher for vertical transverse. Probably low statistics! The PV contamination to the transverse asymmetry is buried under this uncertainty. Fit scheme dependence is ~0.05 ppm (1.0%) C = A PV + background

59. Detector Acceptance Correction Nuruzzaman CIPANP 2015 A single detector measures the average asymmetry over 49% of azimuth Transverse measurement uses octant asymmetries and need to correct for the octant coverage cos ϕ = cos ϕ 0 sin Δ ϕ ΔϕΔϕ 1/M ϕ reg = M ϕ in reg Detector Acceptance Correction reg = 5.1 ppm

60. Cancellation of HCBA with IHWP CIPANP 2015 Nuruzzaman An Insertable Half Wave Plate (IHWP) can flip the electron spin. Inserting IHWP: sign of some helicity correlated (HC) false asymmetries remains unchanged Horizontal Transverse cancellation of HC false asym. Fit function: reg IN/OUT sin( ϕ ) physics asym. changes sign

61. Regression Corrections CIPANP 2015 Nuruzzaman Small corrections, compared to the size of the asymmetry Corrections: ∂ raw ∂T i ∆T i

62. Correction for False Beam Asymmetries CIPANP 2015 Nuruzzaman Not corrected for Polarization Backgrounds Correcting for the helicity correlated changes in beam position, angle and energy using linear regression T i = X, X´, Y, Y´ & E reg = raw - ∂ raw ∂T i ∆T i ∑ i

63. CIPANP 2015 Nuruzzaman