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Introduction to Charge Symmetry Breaking

Introduction to Charge Symmetry Breaking. Introduction What do we know? Remarks on computing cross sections for  0 production. G. A. Miller, UW. Charge Symmetry: QCD if m d =m u , L invariant under u $ d. Isospin invariance [H,T i ]=0, charge independence, CS does NOT imply CI.

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Introduction to Charge Symmetry Breaking

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  1. Introduction to Charge Symmetry Breaking • Introduction • What do we know? • Remarks on computing cross sections for 0 production G. A. Miller, UW

  2. Charge Symmetry: QCD if md=mu, L invariant under u$ d Isospin invariance [H,Ti]=0, charge independence, CS does NOT imply CI

  3. Example- CS holds, charge dependent strong force • m(+)>m(0) , electromagnetic • causes charge dependence of 1S0 scattering lengths • no isospin mixing

  4. Example:CIB is not CSB • CI !(pd!3He0)/(pd !3H+)=1/2 • NOT related by CS • Isospin CG gives 1/2 • deviation caused by isospin mixing • near  threshold- strong  N! N contributes, not ! mixing

  5. Example –proton, neutron proton (u,u,d) neutron (d,d,u) mp=938.3, mn=939.6 MeV If mp=mn, CS,mp<mn, CSB CS pretty good, CSB accounts for mn>mp (mp-mn)Coul¼ 0.8 MeV>0 md-mu>0.8 +1.3 MeV

  6. Miller,Nefkens, Slaus 1990

  7. All CSB arises from md>mu & electromagnetic effects– Miller, Nefkens, Slaus, 1990 All CIB (that is not CSB) is dominated by fundamental electromagnetism (?) CSB studies quark effects in hadronic and nuclear physics

  8. Importance of md-mu • >0, p, H stable, heavy nuclei exist • too large, mn >mp + Binding energy, bound n’s decay, no heavy nuclei • too large, Delta world: m(++)<mp, • <0 p decays, H not stable • Existence of neutrons close enough to proton mass to be stable in nuclei a requirement for life to exist, Agrawal et al(98)

  9. Importance of md-mu • >0, influences extraction of sin2W from neutrino-nucleus scattering • ¼0, to extract strangeness form factors of nucleon from parity violating electron scattering

  10. Outline of remainder Old stuff- NN scattering, nuclear binding energy differences comments on pn! d0 dd!4He0

  11. NN force classification-Henley Miller 1977 Coulomb:VC(1,2)=(e2/4r12)[1+(3(1)+3(2))+3(1)3(2)] I: ISOSCALAR : a +b 1¢2 II:maintain CS, violate CI, charge dep. 3(1)3(2) = 1(pp,nn) or -1 (pn) III: break CS AND CI: (3(1)+3(2)) IV: mixes isospin

  12. VIV»(3(1)-3(2)) • (3(1)-3(2)) |T=0,Tz=0i=2|T=1,Tz=0i isospin mixing • VIV=e(3(1)-3(2))((1)-(2))¢L +f((1)£(2))3((1)£(2))¢ L • magnetic force between p and n is Class IV, current of moving proton int’s with n mag moment • spin flip 3P0!1 P0 TRIUMF, IUCF expts

  13. CLASS III: Miller, Nefkens, Slaus 1990 meson exchange vs EFT? md-mu

  14. Search for class IV forces A -see next slide

  15. ant Where is EFT?

  16. A=3 binding energy difference • B(3He)-B(3H)=764 keV • Electromagnetic effects-model independent, Friar trick use measure form factors EM= 693 § 20 keV, missing 70 • verified in three body calcs • Coon-Barrett - mixing NN, good a, get 80§ 10 keV • Machleidt- Muther TPEP-CSB, good a get 80 keV • good a get 80 keV

  17. Summary of NN CSB meson exchange Where is EFT?

  18. old strong int. calc.

  19. np! d0Theory Requirements • reproduce angular distribution of strong cross section, magnitude • use csb mechanisms consistent with NN csb, cib and  N csb, cib, Gardestig talk

  20. Bacher 14pb Gardestig, Nogga, Fonseca, van Kolck, Horowitz, Hanhart , Niskanen plane wave, simple wave function,  = 23 pb

  21. Initial state interactions • Initial state OPEP, + • HUGE, need to cancel Nogga, Fonseca

  22. plane wave, Gaussian w.f.photon in NNLO, LO not included23 pb vs 14 pb et al

  23. Initial state LO dipole  exchange  3P0 d*(T=1,L=1,S=1), d*d OAM=0,  emission makes dd component of He, estimate using Gaussian wf

  24. Theory requirements: dd!4He0 • start with good strong, csb np! d0 • good wave functions, initial state interactions-strong and electromagnetic • great starts have been made

  25. Suggested plans: dd!4He0 • Stage I: Publish existing calculations, Nogga, Fonseca, Gardestig talks, HUGE  • LO photon exchange absent now, no need to reproduce data • present results in terms of input parameters, do exercises w. params • Stage II: include LO photon exchange, Fonseca

  26. Much to do, let’s do as much as possible here

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