1,029 research outputs found
Comments on "Angular Momentum Transport in Quasi-Keplerian Accretion Disks"
Subramanian, Pujari and Becker (2004) claim that the correct expression for
the angular momentum transport in an accretion disc, which is proportional to
dOmega/dR, can be derived on the basis of the analysis of the epicyclic motion
of gas parcels in adjacent eddies in the disc. We study their argument and show
that their derivation contains several fundamental errors: 1) the biased choice
of the desired formula from an infinite number of formulae; 2) the biased
choice of parcel trajectories; and 3) confusion regarding the reference frames.
Following 1) we could derive, for example, a (invalid) formula in which the
angular momentum transport is proportional to dv_phi/dR, and from 2) we could
even prove that the angular momentum transport is either inward or null. We
present the correct approach to the problem of angular momentum transport in an
accretion disc in terms of mean free path theory.Comment: 9 pages, 2 figures, to appear in Prog. Theor. Phys. Vol.113, No.6,
200
On Kinetic Theory Viscosity in a Rotating Gas
Clarke and Pringle (2004) derived a proper viscosity formula in a rotating
gas by applying mean free path theory. We study their argument in detail and
show that their result can be derived with a much simpler calculational
procedure and physically clearer picture.Comment: 7 pages, 1 figure; Prog. Theor. Phys. Vol. 112, No.
Invariant Regularization of Supersymmetric Chiral Gauge Theory
We formulate a manifestly supersymmetric gauge covariant regularization of
supersymmetric chiral gauge theories. In our scheme, the effective action in
the superfield background field method above one-loop is always supersymmetric
and gauge invariant. The gauge anomaly has a covariant form and can emerge only
in one-loop diagrams with all the external lines being the background gauge
superfield. We also present several illustrative applications in the one-loop
approximation: the self-energy part of the chiral multiplet and of the gauge
multiplet; the super-chiral anomaly and the superconformal anomaly; as the
corresponding anomalous commutators, the Konishi anomaly and an anomalous
supersymmetric transformation law of the supercurrent (the ``central
extension'' of N=1 supersymmetry algebra) and of the R-current.Comment: 43 pages, PHYZZX. Final version to appear in Prog. Theor. Phy
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