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Compton Scattering on Light Nuclei (A=2,3) Deepshikha Shukla UNC-Chapel Hill

Compton Scattering on Light Nuclei (A=2,3) Deepshikha Shukla UNC-Chapel Hill. Collaborators: H. Griesshammer ( George Washington U .), J. McGovern ( U. Manchester ), D. Phillips ( Ohio U .) Previous Work:

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Compton Scattering on Light Nuclei (A=2,3) Deepshikha Shukla UNC-Chapel Hill

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  1. Compton Scattering on Light Nuclei (A=2,3)Deepshikha ShuklaUNC-Chapel Hill Collaborators: H. Griesshammer (George Washington U.), J.McGovern (U. Manchester), D. Phillips (Ohio U.) Previous Work: Beane/Malheiro/McGovern/Phillips/VanKolck; Griesshammer/Hemmert/Hildebrandt/Pasquini/Phillips; Choudhury(Shukla)/Phillips. Choudhury(Shukla)/Nogga/Phillips

  2. NEUTRON l~1Å l~few fm l~1 fm Compton Scattering FB19: Compton Scattering on Light Nuclei

  3. Spin-independent Spin-dependent Polarizabilities FB19: Compton Scattering on Light Nuclei

  4. Light Nuclei (?) • A=2,3: Access Neutron polarizabilities • Not charged • No ‘free neutron’ targets • Computable problem • Ongoing and planned experiments for both processes • At these energies, cPT is an effective tool FB19: Compton Scattering on Light Nuclei

  5. O(e2P2): N2LO J. McGovern (2001) (da, db) Ingredients- 1B mechanisms O(e2): LO Bernard, Kaiser, Meissner (1992) O(e2P): NLO FB19: Compton Scattering on Light Nuclei

  6. HBcPT for Compton Scattering on light Nuclei • Chiral expansion for • Naïve dimensional analysis- • Pn for a vertex with n powers of p or mp • P-2 for pion propagator (1/(p2-mp2)) • P-1 for nucleon propagator (1/(E-p2/2M)) • P4 for loop (loop integral) • P3 for a two-body diagram (d3(p2’-p2) absent) • Wavefunction derived from chiral potential or from potential model FB19: Compton Scattering on Light Nuclei

  7. Ingredients- 2B mechanisms O(e2P: NLO) Beane, Malheiro, Phillips, VanKolck (1999) O(e2P2: N2LO) Beane, Malheiro, McGovern, Phillips, VanKolck (2003) FB19: Compton Scattering on Light Nuclei

  8. Unpolarized gd at O(e2P2) Beane, Malheiro, McGovern, Phillips, VanKolck (2003) FB19: Compton Scattering on Light Nuclei

  9. Ingredients – D explicitly Small Scale Expansion (SSE) – e: D/Lc~mp/Lc; D = MD-MN Hemmert, Holstein, Kambor (1997) + Knochlein (1998) O(e3): NLO (da, db) Alternative – d-counting: Pascalutsa, Phillips (2003) FB19: Compton Scattering on Light Nuclei

  10. Ingredients – Low-energy resummation Griesshammer, Hemmert, Hildebrandt (2005) gd only: 1B NLO: 2B FB19: Compton Scattering on Light Nuclei

  11. Unpolarized gd at O(e3)+Low-energy resumm. Griesshammer, Hemmert, Hildebrandt (2005) FB19: Compton Scattering on Light Nuclei

  12. Current Efforts: Polarized gd - O(e3 )+Low-energy resumm. Griesshammer, McGovern, Phillips, Shukla (2009) Slide from H. Griesshammer FB19: Compton Scattering on Light Nuclei

  13. Polarized gd - O(e3 )+Low-energy resumm. FB19: Compton Scattering on Light Nuclei

  14. Polarized gd - O(e3 )+Low-energy resumm. FB19: Compton Scattering on Light Nuclei

  15. Ongoing Efforts • Comprehensive N2LO calculation with O(d4) effects and low-energy resummation. • Map out all(?) possible observables in the entire kinematic range - would serve as a guide for future experiments (MAxLab, HIgS, MAMI). FB19: Compton Scattering on Light Nuclei

  16. g3He at O(e2P) at 120 MeV (cm) Choudhury, Nogga, Phillips PRL98 (2007) 232303 FB19: Compton Scattering on Light Nuclei

  17. FB19: Compton Scattering on Light Nuclei

  18. FB19: Compton Scattering on Light Nuclei

  19. HIS projection with polarized 3He target Slide from H.Gao 16 NaI Photon flux: 5*107/s, target 1.0*1022/cm2, 45% polarization 500 hours FB19: Compton Scattering on Light Nuclei

  20. Summary & Future Direction • Elastic scattering on A=2,3– “promising” avenue to extract neutron polarizabilities. • We have taken the first step with gHe-3 • Delta degree of freedom • Low-energy resumm. • Comprehensive NNLO gd calculations in progress • Waiting for experimental data! FB19: Compton Scattering on Light Nuclei

  21. 2 p12 q 1 3 O(Q3) O(Q3) FB19: Compton Scattering on Light Nuclei

  22. FB19: Compton Scattering on Light Nuclei

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