1,349 research outputs found
Constituent Quarks and the Spin of the Proton
The constituent quarks are interpreted as bound states, which have an
internal structure. The quark distributions of the proton are related to those
of the constituent quarks. The experiments support this hypothesis. Likewise
the spin structure of the proton is related to the spin structure of the
constituent quarks. We find that about 30% of the spin of a constituent quark
is given by the valence quark, and 70% are provided by the gluons.Comment: 8 page
Quark masses and mixings in the RS1 model with a condensing 4th generation
We study the hierarchy of quark masses and mixings in a model based on a
5-dimensional spacetime with constant curvature of Randall-Sundrum type with
two branes, where the Electroweak Symmetry Breaking is caused dynamically by
the condensation of a 4th generation of quarks, due to underlying physics from
the 5D bulk and the first KK gluons. We first study the hierarchy of quark
masses and mixings that can be obtained from purely adjusting the profile
localizations, finding that realistic masses are not reproduced unless non
trivial hierarchies of underlying 4-fermion interactions from the bulk are
included. Then we study global U(1) symmetries that can be imposed in order to
obtain non-symmetric modified Fritzsch-like textures in the mass matrices that
reproduce reasonably well quark masses and CKM mixings.Comment: Minor changes. Version accepted for publication in JHE
The scalar glueball spectrum
We discuss scenarios for scalar glueballs using arguments based on sum rules,
spectral decomposition, the approximation, the scales of the
strong interaction and the topology of the flux tubes. We analyze the
phenomenological support of those scenarios and their observational
implications. Our investigations hint a rich low lying glueball spectrum.Comment: 11 pages: New title, figure, table and a more detailed comparison
with experiment
Nearly Bi-Maximal Neutrino Mixing, Muon g-2 Anomaly and Lepton-Flavor-Violating Processes
We interpret the newly observed muon g-2 anomaly in the framework of a
leptonic Higgs doublet model with nearly degenerate neutrino masses and nearly
bi-maximal neutrino mixing. Useful constraints are obtained on the rates of
lepton-flavor-violating rare decays ,
and as well as the - conversion ratio .
We find that , and
depend crucially on possible non-zero but samll values of the
neutrino mixing matrix element , and they are also sensitive to the
Dirac-type CP-violating phase. In particular, we show that , and are approximately in the ratio if is much larger than , and in the
ratio if is much lower than , where and are the corresponding mass-squared
differences of atmospheric and solar neutrino oscillations.Comment: LaTex 6 pages (2 PS figures). Phys. Rev. D (in printing
The Spin Content of the Nucleon
The fraction of the nucleon spin that is carried by the quarks, , is computed in lattice QCD with dynamical staggered fermions. We
obtain the value .Comment: (contribution to Lattice 1992), 4 pages + 1 encapsulated postscript
figure, HLRZ 92-81 (In the earlier version the topological charge density was
incorrectly normalized. ERRARE HUMANUM EST!
Hierarchy and Up-Down Parallelism of Quark Mass Matrices
In view of the quark mass hierarchy and in the assumption of the up-down
parallelism, we derive two phenomenologically-favored patterns of Hermitian
quark mass matrices from the quark flavor mixing matrix. We compare one of them
with two existing {\it Anstze} proposed by Rosner and Worah and by
Roberts {\it et al}, and find that only the latter is consistent with the
present experimental data.Comment: RevTex 9 pages. Accepted for publication in Phys. Rev.
Deep inelastic scattering and factorization in the 't Hooft Model
We study in detail deep inelastic scattering in the 't Hooft model. We are
able to analytically check current conservation and to obtain analytic
expressions for the matrix elements with relative precision O(1/Q^2) for 1-x >>
\beta^2/Q^2. This allows us to compute the electron-meson differential cross
section and its moments with 1/Q^2 precision. For the former we find maximal
violations of quark-hadron duality, as it is expected for a large N_c analysis.
For the latter we find violations of the operator product expansion at
next-to-leading order in the 1/Q^2 expansion.Comment: 55 pages, 16 figure
Embedding Phenomenological Quark-Lepton Mass Matrices into SU(5) Gauge Models
We construct phenomenological quark-lepton mass matrices based on S
permutation symmetry in a manner fully compatible with SU(5) grand unification.
The Higgs particles we need are {\bf 5}, {\bf 45} and their conjugates. The
model gives a charge 1/3 quark vs charged lepton mass relation, and also a
good fit to mass-mixing relations for the quark sector, as well as an
attractive mixing pattern for the lepton sector, explaining a large mixing
angle between and , and either large or small
mixing angle, depending on the choice of couplings, consistent
with the currently accepted solutions to the solar neutrino problem.Comment: 12 pages, LaTex file, no figure
RSFQ devices with selective dissipation for quantum information processing
We study the possibility to use frequency dependent damping in RSFQ circuits
as means to reduce dissipation and consequent decoherence in RSFQ/qubit
circuits. We show that stable RSFQ operation can be achieved by shunting the
Josephson junctions with an circuit instead of a plain resistor. We derive
criteria for the stability of such an arrangement, and discuss the effect on
decoherence and the optimisation issues. We also design a simple flux generator
aimed at manipulating flux qubits
Almost Maximal Lepton Mixing with Large T Violation in Neutrino Oscillations and Neutrinoless Double Beta Decay
We point out two simple but instructive possibilities to construct the
charged lepton and neutrino mass matrices, from which the nearly bi-maximal
neutrino mixing with large T violation can naturally emerge. The two lepton
mixing scenarios are compatible very well with current experimental data on
solar and atmospheric neutrino oscillations, and one of them may lead to an
observable T-violating asymmetry between \nu_\mu --> \nu_e and \nu_e -->
\nu_\mu transitions in the long-baseline neutrino oscillation experiments.
Their implications on the neutrinoless double beta decay are also discussed.Comment: RevTex 15 pages (2 PS figures
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