1 / 31

NuTeV Anomaly & Strange-Antistrange Asymmetric Sea

NuTeV Anomaly & Strange-Antistrange Asymmetric Sea. Bo-Qiang Ma Department of Physics, Peking University August 16, 200 4, talk at ICHEP04, Beijing. ?. In collaboration with Yong Ding PLB590(2004)216 hep-ph/0405178. Outline. The NuTeV anamoly and Paschos-Wolfenstein relation

maude
Download Presentation

NuTeV Anomaly & Strange-Antistrange Asymmetric Sea

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. NuTeV Anomaly & Strange-Antistrange Asymmetric Sea Bo-Qiang Ma Department of Physics, Peking University August 16, 2004, talk at ICHEP04, Beijing ? In collaboration with Yong Ding PLB590(2004)216 hep-ph/0405178

  2. Outline • The NuTeV anamoly and Paschos-Wolfenstein relation • A brief review on strange-antistrange asymmetry of the nucleon sea • The strange-antistrange asymmetry in the light-cone baryon-meson fluctuation mdel • Summary

  3. Weinberg Angle from Nuetrino DIS: NuTeV Anamoly • NuTeV Collaboration reported result, PRL88(02)091802 • Other electroweak processes • The three standard deviations could be an indication of new physics beyond standard model if it cannot be explained in conventional physics

  4. The Paschos-Wolfenstein relation • The assumptions for the P-W relationship a isoscalar target b charge symmetry c symmetric strange and antistrange distributions

  5. Non-isoscalar target correction a neutron excess correction(p<n) (S. Kumano(PRD66:111301,2002), the correction issmall; S. A. Kulagin(PRD67:091301,2003), gave the correction is-0.004; S. Davidsonet. al(JHEP,0202: 037,2002), no exactly correction.) b nuclear shadowing and anti-shadowing effect (S. Kuvalenko, I. Schmit and J.J,Yang (杨建军）(PLB546:68,2002), gave the correction changes its sign from-0.00098to 0.00178; J. W, QiuandI. Vitev(hep-ph/0401062), providing2%for the discrepancy) c EMC effect

  6. Charge symmetry violation Perturbative method a quark model (E. Sather, (PLB274:433,1992)) obtained the correction is -0.002, which could reduce the discrepancy40%) b twist two valence parton distributions (J. T. Londergan and A. W. Thomas, (PLB558:132,2003;PRD 67:111901, 2003)) obtained the result should remove roughly one-third of the discrepancy)

  7. c comparing the structure functions (C. Boros, J. T. LonderganandA. W. Thomas (PRL81:4075,1998;PRD59:074021,1999) thought the CSV in the nucleon seais predominant andmuch larger than the valence quarks) d other calculations about CSV (B. Q. Ma (PLB274:111,1992); C. J. BeneshandT. Goldman (PRC55:441,1997) R. M. DavidsonandM. Burkardt (PLB403:134,1997); C. J. BeneshandJ. T. Londergan (PRC58:1218,1998) C. Boros,et. al (PLB468:161,1999) )

  8. non-perturbative method meson cloud model F. G. Cao(曹福广)and A. I. Signal (PRC62:015203,2000), found the CSV in both the valence quark distribution and the nucleon sea are smaller (below 1%) than most quark model predictions (2%-10%) and did not give the correction to the discrepancy

  9. Asymmetric strange-antistrange sea quark distributions meson cloud model:F. G. CaoandA.I. Signal, PLB559(03)229 it is concluded that the asymmetry of the strange and anti-strange issmalland could not affectthe discrepancy

  10. The Strange-Antistrange Asymmetry The strange quark and antiquark distributions are symmetric at leading-orders of perturbative QCD However, it has been argued that there is strange-antistrange distribution asymmetry in pQCD evolution at three-loops from non-vanishing up and down quark valence densities. hep-ph/0404240, S.Catani et al.

  11. Strange-Antistrange Asymmetryfrom Non-Perturbative Sources • Meson Cloud Model A.I. Signal and A.W. Thomas, PLB191(87)205 • Chiral Field M. Burkardt and J. Warr, PRD45(92)958 • Baryon-Meson Fluctuation S.J. Brodsky and B.-Q. Ma, PLB381(96)317

  12. Mechanism for S-Sbar asymmetry _ \ s(x)=s(x)

  13. Strange-Antistrange Asymmetry in phenomenological analyses • V. Barone et al. Global Analysis, EPJC12(00)243 • NuTeV dimuon analysis, hep-ex/0405037 • CTEQ Global Analysis, F. Olnesset. al (hep-ph/0312323), With large uncertainties

  14. A brief comment More precision determinations of strange-antistrange asymmetry should be performed or some sensitive quantities should be used to measure the strangeness asymmetry

  15. Modified P-W relationship • The cross section for neutrino-nucleon DIS a for neutral current interaction

  16. b for charged current interaction • The structure functions of neutral current

  17. The structure functions of charged current

  18. - • The modified P-W relation

  19. Strange-antistrange asymmetry • In light-cone baryon-meson fluctuation model • The dominant baryon-meson configuration for s-sbar

  20. Mechanism for S-Sbar asymmetry

  21. Proton wave functions

  22. The momentum distributions

  23. The probabilities

  24. The probabilities for meson-baryon fluctuation • General case • Our case Brodsky & Ma, PLB381(96)317 Ma, Schmidt, Yang, EPJA12(01)353

  25. The distributions for

  26. The results for • For Gaussian wave function • For power law wave function However, we have also very large Qv (around a factor of 3 larger) in our model calculation, so the ratio of S‾/Qv is reasonable

  27. The results • For Gaussian wave function the discrepancy from 0.005 to 0.0033(0.0009) • For power law wave function the discrepancy from 0.005 to 0.0036(0.0016) Remove the discrepancy 30%-80% between NuTev and other values of Weinberg angle

  28. s(x)/sbar(x) asymmetry s(x)/sbar(x) could be compatible with data by by including some intrinsic strange sea contributions CCFR and NuTeV experimental analyses break net zero strangeness

  29. A Further Chiral Quark Model Study • A further study by using chiral quark model also shows that this strange-antistrange asymmetry has a significant contribution to the Paschos-Wolfenstein relation and can explain the anomaly without sensitivity to input parameters.

  30. Summary • Checked the influence due to strange-antistrange asymmetry and derived the modified Paschos-Wolfenstein relation • Conclude that the correction due to the strange-antistrange asymmetry might be important to explain the NuTeV anamoly

More Related