Neutrino masses from lepton and quark mass relations and neutrino oscillations

Determining the absolute masses of neutrinos is of fundamental importance in particle physics, nuclear physics, and astrophysics. We conjecture that intrinsic mass relations exist between leptons and quarks. Using these relations and neutrino oscillation data, we show that the inverted neutrino mass hierarchy is strongly disfavored and estimate the absolute neutrino masses to be m_{1}=0.21^{+1.70}_{-0.21} \times 10^{-4} {eV}, m_{2}=(8.7 \pm 0.1) \times 10^{-3} {eV}, and m_{3}=(4.9 \pm 0.1) \times 10^{-2} {eV}.Comment: 4 pages, 1 figure; minor corrections, reference list updated; accepted for publication in Phys Rev

Applications of Symmetry Breaking in Determining PDFs of the Nucleon

Studying the possible breaking of various parton model symmetries by the parton distribution functions of the nucleon can provide important information for the non-perturbative structure of hadrons and the strong interaction. We review theoretical calculations for the breaking of flavor symmetry, quark-antiquark symmetry and charge symmetry in the unpolarized and polarized nucleons using the meson cloud model. We report an estimation for the total distribution of strange and antistrange quarks in the nucleon by combining theoretical calculations of SU(3) flavor symmetry breaking with light antiquark distributions obtained from global analysis of available experimental data.Comment: 8 pages, 4 figures, LaTeX, talk presented at Pacific Spin 2011 (June 20-24, 2011, Cairns, Australia), to appear in the conference proceedings (AIP

The flavour asymmetry of polarized anti-quarks in the nucleon

We present a study of the flavour asymmetry of polarized anti-quarks in the nucleon using the meson cloud model. We include contributions both from the vector mesons and the interference terms of pseudoscalar and vector mesons. Employing the bag model, we first give the polarized valence quark distribution of the $\rho$ meson and the interference distributions. Our calculations show that the interference effect mildly increases the prediction for \Delta \dbar(x)-\Delta \ubar(x) at intermediate $x$ region. We also discuss the contribution of `Pauli blocking' to the asymmetry.Comment: 22 pages, LaTex, 5 PS figures. Version to appear in Eur. Phys. J. C. An appendix is added for expressions for the helicity dependent fluctuation functions. An error in the programme for fluctuation function f_{(\pi\rho)\Delta /N} is corrected, which increases numerical results by about 10%. Unchanged conclusion

Determination of the η\eta-η′\eta^\prime mixing angle

We extract $\eta$-$\eta^\prime$ mixing angle and the ratios of decay constants of light pseudoscalar mesons $\pi^0$, $\eta$ and $\eta^\prime$ using recently available BaBar measurements on $\eta$-photon and $\eta^\prime$-photon transition form factors and more accurate experimental data for the masses and two-photon decay widths of the light pseduoscalar mesons.Comment: 5 pages, revtex, no figures, accepted for publication as a Brief Report in Physical Review

Twist-3 contribution to the pion electromagnetic form factor

Non-leading contribution to the pion electromagnetic form factor which comes from the pion twist-3 wave function is analyzed in the modified hard scattering approach (MHSA) proposed by Li and Sterman. This contribution is enhanced significantly due to bound state effect (the twist-3 wave function is independent of the fractional momentum carried by the parton and has a large factor $\sim m_\pi^2/m_0$ with $m_\pi$ being the pion meson mass and $m_0$ being the mean u- and d-quark masses). Consequently, although it is suppressed by the factor $1/Q^2$, the twist-3 contribution is comparable with and even larger than the leading twist (twist-2) contribution at intermediate energy region of $Q^2$ being $2 \sim 40 {GeV}^2$.Comment: 10 pages, 2 fgures, latex. More discussions on the Sudakov effect added, references added. To appear in European Physical Journal C (Zeitschrift fur Physik C

The flavour asymmetry and quark-antiquark asymmetry in the Σ+\Sigma^+-sea

The sea quark content of the $\Sigma^+$ baryon is investigated using light-cone baryon-meson fluctuation model suggested by Brodsky and Ma. It is found that the $\Sigma^+$ sea is flavour asymmetric (\dbar > \ubar > \sbar) and quark-antiquark asymmetric (q \not= \qbar). Our prediction for the flavour asymmetry, \dbar > \ubar > \sbar, is significantly different from the SU(3) prediction (\dbar < \ubar < \sbar), while our prediction for the $d$-\dbar asymmetry is consistent with the SU(3) prediction.Comment: RevTex, 12 pages, 4 Postscript figures. The effects from the input parton distribution evolution are discussed. Conclusions remain. Version to appear in Phys. Lett.