21 research outputs found
Chiral Symmetry Breaking in Quenched Massive Strong-Coupling QED
We present results from a study of subtractive renormalization of the fermion
propagator Dyson-Schwinger equation (DSE) in massive strong-coupling quenched
QED. Results are compared for three different fermion-photon proper vertex
{\it Ans\"{a}tze\/}: bare , minimal Ball-Chiu, and
Curtis-Pennington. The procedure is straightforward to implement and
numerically stable. This is the first study in which this technique is used and
it should prove useful in future DSE studies, whenever renormalization is
required in numerical work.Comment: REVTEX 3.0, 15 pages plus 7 uuencoded PostScript figure
Numerical Study of Hawking Radiation Photosphere Formation around Microscopic Black Holes
Heckler has recently argued that the Hawking radiation emitted from
microscopic black holes has sufficiently strong interactions above a certain
critical temperature that it forms a photosphere, analogous to that of the sun.
In this case, the visible radiation is much cooler than the central temperature
at the Schwarzschild radius, in contrast to the naive expectation for the
observable spectrum. We investigate these ideas more quantitatively by solving
the Boltzmann equation using the test particle method. We confirm that at least
two kinds of photospheres may form: a quark-gluon plasma for black holes of
mass M_{BH} < 5 times 10^{14} g and an electron-positron-photon plasma for
M_{BH} < 2 times 10^{12} g. The QCD photosphere extends from the black hole
horizon to a distance of 0.2--4.0 fm for 10^9 g < M_{BH} < 5 10^{14} g, at
which point quarks and gluons with average energy of order \Lambda_{QCD}
hadronize. The QED photosphere starts at a distance of approximately 700 black
hole radii and dissipates at about 400 fm, where the average energy of the
emitted electrons, positrons and photons is inversely proportional to the black
hole temperature, and significantly higher than was found by Heckler. The
consequences of these photospheres for the cosmic diffuse gamma ray and
antiproton backgrounds are discussed: bounds on the black hole contribution to
the density of the universe are slightly weakened.Comment: 25 pages, Latex, 33 figures ; some incorrect references fixe
Dynamical Left-Right Symmetry Breaking
We study a left--right symmetric model which contains only elementary gauge
boson and fermion fields and no scalars. The phenomenologically required
symmetry breaking emerges dynamically leading to a composite Higgs sector with
a renormalizable effective Lagrangian. We discuss the pattern of symmetry
breaking and phenomenological consequences of this scenario. It is shown that a
viable top quark mass can be achieved for the ratio of the VEVs of the
bi--doublet =~ 1.3--4. For a theoretically
plausible choice of the parameters the right--handed scale can be as low as
; in this case one expects several intermediate and low--scale
scalars in addition to the \SM Higgs boson. These may lead to observable lepton
flavour violation effects including decay with the rate close
to its present experimental upper bound.Comment: 51 pages, LaTeX and uuencoded, packed Postscript figures. The
complete paper, including figures, is also available via WWW at
http://www.cip.physik.tu-muenchen.de/tumphy/d/T30d/PAPERS/
TUM-HEP-222-95.ps.g