The Phantom of the OPERA: Superluminal Neutrinos

This report presents a brief review on the experimental measurements of the muon neutrino velocities from the OPERA, Fermilab and MINOS experiments and that of the (anti)-electron neutrino velocities from the supernova SN1987A, and consequently on the theoretical attempts to attribute the data as signals for superluminality of neutrinos. Different scenarios on how to understand and treat the background fields in the effective field theory frameworks are pointed out. Challenges on interpreting the OPERA result as a signal of neutrino superluminality are briefly reviewed and discussed. It is also pointed out that a covariant picture of Lorentz violation may avoid the refutation on the OPERA experiment.Comment: 10 latex pages. Final version for journal publicatio

NuTeV Anomaly & Strange-Antistrange Asymmetry

The NuTeV Collaboration reported a value of $\sin^{2}\theta_{w}$ measured in neutrino-nucleon deep inelastic scattering, and found that the value is three standard deviations from the world average value of other electroweak measurements. If this result cannot be explained within conventional physics, it must imply some novel physics beyond the standard model. We report the correction from the asymmetric strange-antistrange sea by using both the light-cone baryon-meson fluctuation model and the chiral quark model, and show that a significant part of the NuTeV anomaly can be explained by the strange-antistrange asymmetry.Comment: 4 pages, 2 figures. Talk at ICHEP04, August 16-22, 2004, Beijing, Chin

The x-Dependent Helicity Distributions for Valence Quarks in Nucleons

We derive simple relations between the polarized and unpolarized valence quark distributions in a light-cone SU(6) quark-spectator model for nucleons. The explicit x-dependent Wigner rotation effect for the light-flavor quarks is calculated. It is shown that the mass difference between the scalar and vector spectators could reproduce the up and down valence quark asymmetry that accounts for the observed ratio $F_2^{n}/F_2^{p}$. The proton, neutron, and deuteron polarization asymmetries, $A_1^p$, $A_1^n$, and $A_1^d$, are in agreement with the available data by taking into account the Wigner rotation effect. The calculated $x$-dependent helicity distributions of the up and down valence quarks are compared with the recent results from semi-inclusive hadron asymmetries in polarized deep inelastic scattering by the Spin Muon Collaboration.Comment: 20 pages, latex, with 4 postscript figures, to be published in Phys.Lett.B, small corrections to reference

NuTeV Anomaly Versus Strange-Antistrange Asymmetry

We report the correction from the asymmetric strange-antistrange sea of the nucleon by using both the light-cone baryon-meson fluctuation model and the chiral quark model, and show that a significant part of the NuTeV anomaly can be explained by the strange-antistrange asymmetry. We also show that the calculated $s/\bar{s}$ asymmetry are compatible with the NuTeV data by including some additional symmetric $s/\bar{s}$ quark contribution.Comment: 4 Latex pages, 1 figure, talk presented at International Conference on QCD and Hadronic Physics, Beijing, China, June 16-20, 200

Effect due to compositeness of nucleons in deep inelastic lepton nucleus scattering

The off-shell behaviors of bound nucleons in deep inelastic lepton nucleus scattering are discussed in two scenarios with the basic constituents chosen to be baryon-mesons and quark-gluons respectively in light-cone formalism. It is found that when taking into account the effect due to internal quark structure of nucleons, the derived scaling variable for bound nucleons and the calculated nuclear structure functions are different from those in considering the baryon-mesons as the effective elementary constituents. This implies that the pure baryon-meson descriptions of nuclei give the inaccurate off-shell behavior of the bound nucleon structure function, thereby the quark-gluons seem to be the most appropriate degrees of freedom for nuclear descriptions. It is also shown that the EMC effect cannot be explained by nuclear binding effect from a sound theoretical basis.Comment: 18 LaTex pages, 4 figures (not included), to be published in Int.J.Mod Phys.