267 research outputs found
Charged Randall-Sundrum black holes and N=4 super Yang-Mills in AdS(2)xS(2)
We obtain some exact results for black holes in the Randall-Sundrum model
with a single brane. We consider an extreme black hole charged with respect to
a Maxwell field on the brane. The near-horizon geometry is determined. The
induced metric on the brane and the black hole entropy are compared with the
predictions of 4d General Relativity. There is good agreement for large black
holes, with calculable subleading corrections. As a separate application, the
bulk solution provides a gravitational dual for (strongly coupled, large N) N=4
SYM in AdS(2)xS(2) for arbitrary relative size of AdS(2) and S(2).Comment: 13 page
The Impact of a Very Weak and Thin Upper Asthenosphere on Subduction Motions
Recent geophysical observations report the presence of a very weak and thin upperasthenosphere underneath subducting oceanic plates at convergent margins. Along these margins, trenchmigrations are significantly slower than plate convergence rates. We use numerical models to assess therole of a weak upper asthenospheric layer on plate and trench motions. We show that the presence of thislayer alone can enhance an advancing trend for the motion of the plate and hamper trench retreat. Thismechanism provides a novel and alternative explanation for the slow rates of trench migration andfast-moving plates observed globally at natural subduction zones
Complex Regge poles in the cut j plane: Pion-nucleon charge-exchange scattering
The structure of the pole-cut combination in πN charge-exchange scattering for t<~0 is represented by a pair of complex poles. Excellent fits to the πN charge-exchange differential cross section, polarization, and total cross-section difference σt(π-p)-σt(π+p) are obtained for the two examples considered, Imα=gsqrt[-t] and Imα=g. The phases of the residues are allowed to vary and a zero in ImA′(-) (the "crossover" zero) is obtained
Model of the Quark Mixing Matrix
The structure of the Cabibbo-Kobayashi-Maskawa (CKM) matrix is analyzed from
the standpoint of a composite model. A model is constructed with three families
of quarks, by taking tensor products of sufficient numbers of spin-1/2
representations and imagining the dominant terms in the mass matrix to arise
from spin-spin interactions. Generic results then obtained include the familiar
relation , and a less frequently
seen relation . The magnitudes of
and come out naturally to be of the right order. The phase in
the CKM matrix can be put in by hand, but its origin remains obscure.Comment: Presented by Mihir P. Worah at DPF 92 Meeting, Fermilab, November,
1992. 3 pages, LaTeX fil
On dynamics of fermion generations
The hierarchy of fermion masses and EW symmetry breaking without elementary
Higgs is studied on the basis of strong gauge field distributions governing the
EW dynamics. The mechanism of symmetry breaking due to quark bilinears
condensation is generalized to the case, when higher field correlators are
present in the EW vacuum. Resulting wave functional yields several minima of
quark bilinears, giving masses of three (or more) generations. Mixing is
suggested to be due to kink solutions of the same wave functional. For a
special form of this mixing ("coherent mixing") a realistic hierarhy of masses
and of CKM coefficients is obtained and arguments in favor of the fourth
generation are given. Possible important role of topological charges for CP
violating phases and small masses of the first generation is stressed.Comment: 31 pages, typos corrected, references adde
Test of the Dimopouos-Hall-Raby Ansatz for Fermion Mass Matrices
By evolution of fermion mass matrices of the Fritzsch and the Georgi-Jarlskog
forms from the supersymmetric grand unified scale, DHR obtained predictions for
the quark masses and mixings. Using Monte Carlo methods we test these
predictions against the latest determinations of the mixings, the CP-violating
parameter epsilon_K and the B_d^0--Bbar_d^0 mixing parameter r_d. The
acceptable solutions closely specify the quark masses and mixings, but lie at
the edges of allowed regions at 90% confidence level.Comment: 11 pages, 1 figure (not included
Neutrino masses from universal Fermion mixing
If three right-handed neutrinos are added to the Standard Model, then, for
the three known generations, there are six quarks and six leptons. It is then
natural to assume that the symmetry considerations that have been applied to
the quark matrices are also valid for the lepton mass matrices. Under this
assumption, the solar and atmospheric neutrino data can be used to determine
the individual neutrino masses. Using the \chi^2 fit, it is found that the mass
of the lightest neutrino is (2-5)\times10^{-3} eV, that of the next heavier
neutrino is (10-13)\times10^{-3} eV, while the mass of the heaviest neutrino is
(52-54)\times10^{-3} eV.Comment: 27 pages, LaTeX, including several figure
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