1. 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: Beane/Malheiro/McGovern/Phillips/VanKolck; Griesshammer/Hemmert/Hildebrandt/Pasquini/Phillips; Choudhury(Shukla)/Phillips. Choudhury(Shukla)/Nogga/Phillips

2. 31/08/2009FB19: Compton Scattering on Light Nuclei2 Compton Scattering  ~1Å  ~few fm  ~1 fm NEUTRON

3. 31/08/2009FB19: Compton Scattering on Light Nuclei3 Polarizabilities Spin-independent Spin-dependent

4. 31/08/2009FB19: Compton Scattering on Light Nuclei4 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,  PT is an effective tool

5. 31/08/2009FB19: Compton Scattering on Light Nuclei5 Ingredients- 1B mechanisms O(e 2 ): LO O(e 2 P): NLO Bernard, Kaiser, Meissner (1992) O(e 2 P 2 ): N 2 LO ( ,  J. McGovern (2001)

6. 31/08/2009FB19: Compton Scattering on Light Nuclei6 HB  PT for Compton Scattering on light Nuclei Chiral expansion for Naïve dimensional analysis-  P n for a vertex with n powers of p or m p  P -2 for pion propagator (1/(p 2 -m  2 ))  P -1 for nucleon propagator (1/(E-p 2 /2M))  P 4 for loop (loop integral)  P 3 for a two-body diagram (  3 (p 2 ’-p 2 ) absent) Wavefunction derived from chiral potential or from potential model

7. 31/08/2009FB19: Compton Scattering on Light Nuclei7 Ingredients- 2B mechanisms O(e 2 P 2 : N 2 LO) O(e 2 P: NLO) Beane, Malheiro, McGovern, Phillips, VanKolck (2003) Beane, Malheiro, Phillips, VanKolck (1999)

8. 31/08/2009FB19: Compton Scattering on Light Nuclei8 Unpolarized  d at O(e 2 P 2 ) Beane, Malheiro, McGovern, Phillips, VanKolck (2003)

9. 31/08/2009FB19: Compton Scattering on Light Nuclei9 Ingredients –  explicitly Small Scale Expansion (SSE) –  :  /   ~m  /    M  -M N ( ,  O(  3 ): NLO Alternative –  -counting: Hemmert, Holstein, Kambor (1997) + Knochlein (1998) Pascalutsa, Phillips (2003)

10. 31/08/2009FB19: Compton Scattering on Light Nuclei10 Ingredients – Low-energy resummation  d only: NLO: 1B 2B Griesshammer, Hemmert, Hildebrandt (2005)

11. 31/08/2009FB19: Compton Scattering on Light Nuclei11 Unpolarized  d at O(  3 )+Low-energy resumm. Griesshammer, Hemmert, Hildebrandt (2005)

12. 31/08/2009FB19: Compton Scattering on Light Nuclei12 Current Efforts: Polarized  d - O(  3 )+Low-energy resumm. Slide from H. Griesshammer Griesshammer, McGovern, Phillips, Shukla (2009)

13. 31/08/2009FB19: Compton Scattering on Light Nuclei13 Polarized  d - O(  3 )+Low-energy resumm.

14. 31/08/2009FB19: Compton Scattering on Light Nuclei14 Polarized  d - O(  3 )+Low-energy resumm.

15. 31/08/2009FB19: Compton Scattering on Light Nuclei15 Ongoing Efforts Comprehensive N 2 LO calculation with O(  4 ) effects and low-energy resummation. Map out all(?) possible observables in the entire kinematic range - would serve as a guide for future experiments (MAxLab, HI  S, MAMI).

16. 31/08/2009FB19: Compton Scattering on Light Nuclei16  3 He at O(e 2 P) at 120 MeV (cm) Choudhury, Nogga, Phillips PRL98 (2007) 232303

17. 31/08/2009FB19: Compton Scattering on Light Nuclei17

18. 31/08/2009FB19: Compton Scattering on Light Nuclei18

19. 31/08/2009FB19: Compton Scattering on Light Nuclei19 HI  S projection with polarized 3 He target Photon flux: 5*10 7 /s, target 1.0*10 22 /cm 2, 45% polarization 500 hours 16 NaI Slide from H.Gao

20. 31/08/2009FB19: Compton Scattering on Light Nuclei20 Summary & Future Direction Elastic scattering on A=2,3– “promising” avenue to extract neutron polarizabilities. We have taken the first step with  He-3 Delta degree of freedom Low-energy resumm. Comprehensive NNLO  d calculations in progress Waiting for experimental data!

21. 31/08/2009FB19: Compton Scattering on Light Nuclei21 O(Q 3 ) 1 2 3 p 12 q

22. 31/08/2009FB19: Compton Scattering on Light Nuclei22