 ∂tu = − i ∂xj (ajk(x, t, u, ū,∇u,∇ū)∂xku) +~b1(x, t, u, ū,∇u,∇ū) · ∇u+~b2(x, t, u, ū,∇u,∇ū) · ∇ū + c1(x, t, u, ū)u+ c2(x, t, u, ū)ū+ f(x, t), where x ∈ R, t > 0, and A = (ajk(·))j,k=1,..,n is a real, symmetric matrix. Our aim is to study the existence, uniqueness and regularity of local solutions to the initial value problem (IVP) associated to the equation (1.1). In the case where A = (ajk(·...

We use the meson cloud model of the nucleon to calculate distribution functions for (d̄− ū) and d̄/ū in the proton. Including the effect of the omega meson cloud, with a coupling constant g ω/4π ≈ 8, allows a reasonably good description of the data. There has been considerable interest in the flavor dependence of the proton’s quark distributions. About ten years ago, the NMC measurement of the in...

In this paper, one-dimensional (1D) nonlinear Schrödinger equation iut − uxx +mu+ g(u, ū) ū = 0, with Periodic Boundary Conditions is considered; m / ∈ 1 12Z is a real parameter and the nonlinearity g(u, ū)= ∑ j,l,j+l 4 ajlu j ū , aj l = alj ∈ R, a22 = 0 is a real analytic function in a neighborhood of the origin. The KAM machinery is adapted to fit the above equation so as to construct small-a...

The existence of a shallow or virtual tetraquark state, c c ū d̄, is discussed. Using the putative masses for the doubly charmed baryons (c c u/c c d) from SELEX, the mass of the c c ū d̄ state is estimated to be about 3.9GeV , only slightly above the DD threshold. The experimental signatures for various c c ū d̄ masses are also discussed. Typeset using REVTEX 1

The existence of a shallow or virtual tetraquark state, c c ū d̄, is discussed. Using the putative masses for the doubly charmed baryons (c c u/c c d) from SELEX, the mass of the c c ū d̄ state is estimated to be about 3.9GeV , only slightly above the DD threshold. The experimental signatures for various c c ū d̄ masses are also discussed. Typeset using REVTEX 1

ū The co-occurrence of psychotic symptoms such as delusions and formal thought disorder points towards the existence of a psychiatric disease. ū Comorbid negative symptoms suggest a schizophrenia spectrum disorder. ū Age of onset can be a coarse but valuable indicator for distinguishing between hallucinations occurring in the context of neurological and psychiatric disorders. The former are ass...

The flavor asymmetry of the polarized light sea, ∆ū −∆d̄, discriminates between different model calculations of helicity densities. We show that the chiral chromodielectric model, differently from models based on a 1/Nc expansion, predicts a small value for this asymmetry, what seems in agreement with preliminary HERMES data. 1. Following the discovery that the quark contribution to the spin of ...

We examine the space-time properties of the distributions of (d̄− ū) and d̄/ū in the proton. The difference of the antiquark distributions shows the expected peak at the approximate pion Compton wavelength and is supportive of the thesis that the meson cloud of the nucleon is at the origin of the asymmetry of (d̄ − ū), with the pion cloud playing a dominant role. The partonic distribution function...

We study the possible flavour asymmetry, ū 6= d̄, of the light quark sea distributions of the proton. We discuss the information that is at present available from data on deep-inelastic lepton-nucleon scattering and from DrellYan production on various nuclear targets. We show that the ratio of dilepton yields on hydrogen and deuterium targets is very sensitive to ū − d̄. The increased precision o...