310 research outputs found
Introduction to effective Lagrangians for QCD
A brief introduction to the effective Lagrangian treatment of QCD (in the
sense of using fields representing physical particles rather than quarks and
gluons) will be given. The historical evolution of the subject will be
discussed. Some background material related to a recent model for Gamma Ray
Bursters will be given. Finally, some recent work on low energy strong
interactions will be mentioned.Comment: 12 pages, 2 figures, talk at "Compact stars in the QCD phase
diagram", Copenhagen, Aug. 15-18, 200
Remark on the Potential Function of the Linear Sigma Model
It is shown that the potential functions for the ordinary linear sigma model
can be divided into two topographically different types depending on whether
the quantity is greater than or less than nine.
Since the Wigner-Weyl mode (R=1) and the Nambu-Goldstone mode (
belong to different regions, we speculate that this classification may provide
a generalization to the broken symmetry situation, which could be convenient
for roughly characterizing different possible applications of the model. It is
noted that a more complicated potential does not so much change this picture as
add different new regions.Comment: 26 pages, 11 figures (gzipped
Toy Model for Breaking Super Gauge Theories at the Effective Lagrangian Level
We propose a toy model to illustrate how the effective Lagrangian for super
QCD might go over to the one for ordinary QCD by a mechanism whereby the
gluinos and squarks in the fundamental theory decouple below a given
supersymmetry breaking scale . The implementation of this approach involves
a suitable choice of possible supersymmetry breaking terms. An amusing feature
of the model is the emergence of the ordinary QCD degrees of freedom which were
hidden in the auxiliary fields of the supersymmetric effective Lagrangian.Comment: 21 pages (ReVTeX), 1 PostScript Figur
Neutrinos with velocities greater than c ?
A possible explanation of the results of the OPERA experiment is presented.
Assuming that the usual value of c should be interpreted as the velocity of
light in dark matter, we call the "true" velocity of light in vacuum, .
Then the OPERA neutrinos can be faster than c but slower than . We also
discuss the relationship between and neutrino masses.Comment: 5 pages, 1 figure, additional references adde
Absolute neutrino masses
We discuss the possibility of using experiments timing the propagation of
neutrino beams over large distances to help determine the absolute masses of
the three neutrinos.Comment: 3 pages, 2 figure
Nonperturbative Results for Yang-Mills Theories
Some non perturbative aspects of the pure SU(3) Yang-Mills theory are
investigated assuming a specific form of the beta function, based on a recent
modification by Ryttov and Sannino of the known one for supersymmetric gauge
theories. The characteristic feature is a pole at a particular value of the
coupling constant, g. First it is noted, using dimensional analysis, that
physical quantities behave smoothly as one travels from one side of the pole to
the other. Then it is argued that the form of the integrated beta function
g(m), where m is the mass scale, determines the mass gap of the theory.
Assuming the usual QCD value one finds it to be 1.67 GeV, which is in
surprisingly good agreement with a quenched lattice calculation. A similar
calculation is made for the supersymmetric Yang-Mills theory where the
corresponding beta function is considered to be exact.Comment: RevTeX, 2colmuns, 6 pages and 7 figure
Two or Four: A Hint from Scalar Mesons in Radiative phi Decays ?
In this write-up, we summarize our recent analysis of radiative decays
involving light scalar mesons. Our analysis using the vector meson dominance
model at tree level indicates that it may be difficult to distinguish
picture and picture for the light scalar nonet.
Our result on the process of shows that the
derivative-type interaction reproduces experimental data below
950 GeV well, but gives a poor fit above 950 GeV, i.e., in the energy region
around the mass of , but that the discrepancy can be compensated by
the effect of the loop.Comment: Talk given by M. Harada at Yukawa International Seminar (YKIS) 2006
``New Frontiers in QCD -Exotic Hadrons and Hadronic Matter-'
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