954 research outputs found
Nutev anomaly & strange-antistrange asymmetry
No full textThe 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 meson-baryon model and the chiral quark model, and show that a significant part of the NuTeV anomaly can be explained by the strange-antistrange asymmetry.Physics, Particles & FieldsCPCI-S(ISTP)
NuTeV anomaly versus strange-antistrange asymmetry
No full textWe 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/(s) over bar asymmetry are compatible with the NuTeV data by including some additional symmetric s/(s) over bar quark contribution.Physics, NuclearPhysics, Particles & FieldsSCI(E)CPCI-S(ISTP)
Unified parametrization of quark and lepton mixing matrices
No full textWe present a unified parametrization of quark and lepton mixing matrices. By using some simple relations between the mixing angles of quarks and leptons, i.e., the quark-lepton complementarity, we parametrize the lepton mixing matrix with the Wolfenstein parameters lambda and A of the quark mixing matrix. It is shown that the Wolfenstein parameter lambda can measure both the deviation of the quark mixing matrix from the unit matrix, and the deviation of the lepton mixing matrix from the exactly bimaximal mixing pattern.Astronomy & AstrophysicsPhysics, Particles & FieldsSCI(E)0ARTICLE9null7
Parity of antidecuplet baryons reexamined from chiral soliton models
No full textWe recalculate masses and widths of antidecuplet baryons in the case of positive parity from chiral soliton models, provided that the member Xi(3/2) of the antidecuplet has a mass 1.86 GeV, as reported recently. Calculations show that there are no convincing candidates for the nonexotic members of the antidecuplet available in the baryon listings. Up to the leading order of m(s) and 1/N-c, the width formula for the decay of the antidecuplet baryons to the octet depends only on SU(3) symmetry model independently, except the coupling constant. Similarly, we give a width formula for the decay of negative parity baryons belonging to certain SU(3) baryon multiplets by pure symmetry consideration. By this formula, we find that if we have an antidecuplet with negative parity and that the masses are the same as those given by chiral soltion models, the identification of N(1650) as N-(10) over bar are inconsistent with experiments for N(1650)-->Npi while the widths agree with other two decay channels involving strangeness. And Sigma(1750) seems to be a reasonable candidate for Sigma((10) over bar).Astronomy & AstrophysicsPhysics, Particles & FieldsSCI(E)5ARTICLE9null7
Detection of cosmic neutrino clustering by cosmic ray spectra
No full textWe propose a method to investigate the scenario that cosmic relic neutrinos are highly clustered around stars and galaxies, or dark-matter clusters, rather than uniformly distributed in the universe. Such a scenario can be detected or constrained by the interaction of high-energy cosmic ray protons and nuclei with the cosmic neutrinos. There should be an observable signature in the energy spectra of cosmic ray protons and nuclei for a neutrino clustering factor beyond 10(13). We provide a relation on the signature onset positions between proton and nuclei spectra, and discuss possible support from existing experiments. It is also suggested that the relative abundance of cosmic ray nuclei may detect or constrain the cosmic neutrinos with smaller clustering.Physics, MultidisciplinarySCI(E)EI5ARTICLEnull
Fragmentation functions of mesons in the Field-Feynman model
No full textThe fragmentation functions of the pion with distinction between D-u(pi+), D-d(pi+), and D-s(pi+) are studied in the Field-Feynman recursive model, by taking into account the flavor structure in the excitation of quark-antiquark pairs by the initial quarks. The obtained analytical results are compatible with the available empirical results. The framework is also extended to predict the fragmentation functions of the kaon with distinction between D-(s) over bar(K+)(z), D-u(K+)(z), D-s(K+)(z), and D-d(K+)(z). This work gives a significant modification of the original model, and the predictions can be tested by future experiments on the fragmentation functions of the kaon.Physics, Particles & FieldsSCI(E)0ARTICLE2207-2123
Nonzero transversity distribution of the pion in a quark-spectator-antiquark model
No full textWe calculate the nonzero (naive) T-odd transverse momentum dependent transversity distribution h(1)(perpendicular to)(x,k(perpendicular to)(2)) of the pion in a quark-spectator-antiquark model. The final-state interaction is modeled by the approximation of one gluon exchange between the quark and the antiquark spectator. Using our model result we estimate the unsuppressed cos2phi azimuthal asymmetry in unpolarized pi(-)p Drell-Yan process. We find that the transverse momentum dependence of h(1)(perpendicular to)(x,k(perpendicular to)(2)) of the pion is the same as that of h(1)(perpendicular to)(x,k(perpendicular to)(2)) of the proton calculated from the quark-scalar-diquark model, although the x dependencies of them are different from each other. This suggests a connection between cos2phi asymmetries in Drell-Yan processes with different initial hadrons.Astronomy & AstrophysicsPhysics, Particles & FieldsSCI(E)30ARTICLE9null7
Decay probability ratio of pentaquark Theta(+) state
No full textThe pentaquark state of Theta(+)(uudd (s) over bar) has been observed to decay with two decay modes: Theta(+) --> nK(+) and Theta(+) --> pK(0). The decay probability ratio of the two decay modes is studied with general symmetry consideration of isospin, spin and parity. We arrive at a result of the ratio Gamma(Theta(+)-->nK(+))/<(&UGamma;(&UTheta;+ &RARR; pK(0)))over bar> = (alpha - beta)(2)/<((&alpha; + &beta;)(2))over bar> (k(1/)(k(2)) over bar (2L+1) which is valid for the Theta(+) state to be a pure isoscalar or isovector state, or an isoscalar and isovector mixing state, or an isotensor state with mixture of isoscalar and isovector components with coefficients alpha and beta. The dependence on spin and parity of the pentaquark Theta(+) state is found to be small due to small difference between the center-of-mass decay momenta k(1) and k(2) of the two decay modes. We also provide an analysis on the constraint of the isospin of Theta(+) from the absence of a peak in the pK(+) invariant mass distribution in the gammap --> pK(+)K(-) process. Future experimental results about the decay probability ratio may provide information about the properties of the pentaquark Theta(+) state.Physics, NuclearPhysics, Particles & FieldsPhysics, MathematicalSCI(E)0ARTICLE302289-22971
Photon-meson transition form factors of light pseudoscalar mesons
No full textThe photon-meson transition form factors of light pseudoscalar mesons pi(0), eta, and eta' are systematically calculated in a light-cone framework, which is applicable as a light-cone quark model at low Q(2) and is also physically in accordance with the light-cone perturbative quantum chromodynamics approach at large Q(2). The calculated results agree with the available experimental data at high-energy scale. We also predict the low Q(2) behaviors of the photon-meson transition form factors of pi(0), eta, and eta', which are measurable in the e+A(Nucleus)-->e+A+M process via the Primakoff effect at JLab and DESY.Astronomy & AstrophysicsPhysics, Particles & FieldsSCI(E)0ARTICLE1null7
THE PROTON SPIN AND THE WIGNER ROTATION
No full textIt is shown that in both the gluonic and strange sea explanations of the Ellis-Jaffe sum rule violation discovered by the European Muon Collaboration (EMC), the spin of the proton, when viewed in its rest reference frame, could be fully provided by quarks and antiquarks within a simple quark model picture, taken into account the relativistic effect from the Wigner rotation.Physics, Particles & FieldsSCI(E)83ARTICLE3479-4825
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