Search for R-parity violating Supersymmetric effects in the neutron beta decay

1. Search for R-parity violatingSupersymmetric effectsin the neutron beta decay N.Yamanaka (Osaka University) In collaboration with T. Sato (Osaka univ.), T. Kubota (Osaka univ.) 2009年8月12日 at KEK arXiv:0908.1007 [hep-ph]

2. Contents • Introduction • Neutron beta decay • MSSM and R-parity violation • Neutron Beta decay within RPVMSSM • Analysis • Summary

3. Introduction

4. Go beyond the Standard Model Standard Model: • Gauge group SU(3)C×SU(2)L×U(1)Y • 3 generations • 1 Higgs SU(2)L doublet gauge boson Higgs boson lepton quark Reasons to go beyond the SM: • Hierarchy problems • Particle-antiparticle asymmetry (too many particles!) • No candidates of Dark Matter in SM • Evidence of neutrino oscillations (1998 ～) …

5. Approach to New Physics High energy approach: Energy above the new physics threshold ⇒ create new particles Ex: LHC (CERN) Low energy approach: Very accurate experiments are now possible: ⇒ Observe the small discrepancy from SM by precise measurements of low energy phenomena ⇒ Search for New physics beyond SM • Groups: • J-PARC • LANSCE • PSI • ILL • … • Phenomena: • EDMs • Decay phenomena • Muon g-2 • … Neutron beta decay

6. d u e- d u ~ dR ~ eL - - ne ne e- New physics from beta decay Neutron beta decay may involve many New Physics Minimal supersymmetric standard model (MSSM) R-parity violating MSSM Left-Right symmetric model Charged Higgs exchange Leptoquark exchange …

7. Object Recently, • Measurement of R coefficient of the neutron beta decay (Kozela et al. (PSI), Phys.Rev.Lett.102, 2009) • Bound on Fierz interference term of the beta decay (Hardy & Towner, Phys. Rev. C 79, 055502, 2009) R-parity violating MSSM contributes to the scalarinteraction at the tree level !! ⇒ Both give scalar interaction of the neutron beta decay Object: Investigate RPVMSSM contribution to the neutron beta decay.

8. Neutron beta decay

9. n p W e- n p V-A interaction: Standard Model Scalar interaction: Exotic! e- ~ eL - - ne ne Neutron beta decay Process: (～100%) Transition: Interaction Hamiltonian:

10. Angular correlations Angular dependence of the beta decay Decay distribution: (no polarization) (neutron polarization) (e- polarization) (neutron&e- polarization) neutrino momentum & e- polarization: ⇒ new terms!! Jackson, Treiman, Wyld, Nucl. Phys. 4, 206 (1957)

11. MSSM and R-parity violation

12. ⇔ particles s-particles Supersymmetry ⇔ Symmetry between boson & fermion: ⇒ Each particle has a “super-partner” fermion boson Why SUSY? • SUSY cancels power divergences (Fine tuning) • SUSY can break the EW symmetry • Accurate GUT at 1016GeV • Dark matter, etc. … Minimal Supersymmetric Standard Model (MSSM): ⇒ Gauge invariant, renormalizable, R-parity conserving ⇒ Phenomenological extension of the SM!!

13. d u ~ eL R-parity violation R parity: ⇒Conservation of baryon and lepton number in MSSM. RPVMSSM: Add R-parity violating interactions to the MSSM □R parity violating lagrangian: L or B violating

14. Neutron beta decaywithin RPVMSSM

15. Steps of calculation Plan: Beta decay within R parity violating MSSM Neutron Beta decay effective interaction Angular correlation (coefficients)

16. d u Yukawa interaction!! ~ eL RPV lagrangian & limits RPV lagrangian: ~ ~ Barger, Giudice, Han, Phys. Rev. D409, 2987 (1989) Barbier et al., Phys. Rept. 420, 1 (2005) Faessler, Kovalenko, Simkovic, Phys. Rev. D58, 115004 (1998) […] : sfermion mass in unit of 100 GeV

17. d u W e- d u e- d u ~ dR ~ eL - - - ne ne ne e- Neutron beta decay withR-parity violation SM contribution: Selectron exchange diagram: Down squark exchange diagram: Absorbed in Vud⇒ Neglect

18. Effective interaction Effective interaction constructed from quark amplitude: (pseudoscalar interaction neglected due to non-relativistic approx) Vector, axial and scalar constants: (CVC assertion) (Experiment) (Our work)

19. Result • Approx. used: • Static approx. of nucleon • Scalar & V-A interference only • O(me/MN) neglected

21. Analysis

22. Survey of superallowed Fermi transition Test of CVC with 20 superallowed 0+→0+ beta decay. CVC assertion ⇒ Vector interaction not renormalized Ft identical in nuclear medium for 0+→0+ transition Test of CVC: Corrected Ft value (isospin symmetry breaking correction and radiative corrections) In 0+→0+ transition, effect of (real part of) scalar interaction shows up in Fierz interference term Fierz interference term ⇒ limit to Re(Cs) !! J.C. Hardy, I.S. Towner, Phys. Rev. C79, 055502 (2009)

23. R coefficient R correlation: Sensitive to the imaginary part of Cs Experimental status: Rexp = 0.008 ± 0.011 ± 0.005 Kozela et al.(PSI), PRL102 (2009) SM: RSM≦ 10-14 Herczeg, Phys. Rev. D56 (1997) Final state interaction: Rfsi = 0.00086 × me/pe Jackson, Treiman, Wyld, Nucl. Phys. 4, 206 (1957) 10-4 10-2 10-14 SM FSI RPV Exp

24. New bounds Current limit: (plot with all mSUSY= 100 GeV)

25. Summary We have investigated the R-parity violating contribution to the neutron beta decay. The following new constraints were established:

26. Future prospects D coefficient: V-A only (SM) 0 Fsi O(10-5) RPVMSSM 0 (tree level, O(me/mn) contribution neglected !) d u W _ ne e- L, S, T, U, W coefficients: Zero in V-A only (SM), but RPV contributions exist S,T,U,W are direct probe of the real part of scalar interaction!! Loop contribution: Non-scalar interactions at the one-loop level. ⇒ Possibility of large contribution to some angular correlations?