52 research outputs found
The Isgur-Wise function in a relativistic model for system
We use the Dirac equation with a ``(asymptotically free) Coulomb + (Lorentz
scalar) linear '' potential to estimate the light quark wavefunction for mesons in the limit . We use these wavefunctions to
calculate the Isgur-Wise function for orbital and radial
ground states in the phenomenologically interesting range . We find a simple expression for the zero-recoil slope, , where is the energy eigenvalue
of the light quark, which can be identified with the parameter
of the Heavy Quark Effective Theory. This result implies an upper bound of
for the slope . Also, because for a very light quark the size of the meson is determined mainly by the
``confining'' term in the potential , the shape of
is seen to be mostly sensitive to the dimensionless
ratio . We present results for the ranges of
parameters , and
light quark masses and compare to existing
experimental data and other theoretical estimates. Fits to the data give:
,
and [ARGUS
'93]; , and
[CLEO '93]; ${\bar\Lambda_{u,d}}^2/Comment: 22 pages, Latex, 4 figures (not included) available by fax or via
email upon reques
Radiative Decay in the Light Cone QCD Approach
We calculate to the leading twist 2 accuracy the rate for the decay using the light cone QCD sume rules. We find . The results are used
to test the applicability of the constituent quark model approximation to the
same process.The latter estimate is proportional to , where is the "constituent quark mass", indicating
that the process is of long distance type. We find that the two approaches
yield similar results for the rate with the choice . This indicates that the constituent quark model may be used for estimates of
the radiative "annihilation" contribution to this and other radiative decays.
We point out that this decay may be useful for the measurement of .Comment: latex, 14 pages, one figure is available upon reques
Flavour Universal Dynamical Electroweak Symmetry Breaking
The top condensate see-saw mechanism of Dobrescu and Hill allows electroweak
symmetry to be broken while deferring the problem of flavour to an electroweak
singlet, massive sector. We provide an extended version of the singlet sector
that naturally accommodates realistic masses for all the standard model
fermions, which play an equal role in breaking electroweak symmetry. The models
result in a relatively light composite Higgs sector with masses typically in
the range of (400-700)~GeV. In more complete models the dynamics will
presumably be driven by a broken gauged family or flavour symmetry group. As an
example of the higher scale dynamics a fully dynamical model of the quark
sector with a GIM mechanism is presented, based on an earlier top condensation
model of King using broken family gauge symmetry interactions (that model was
itself based on a technicolour model of Georgi). The crucial extra ingredient
is a reinterpretation of the condensates that form when several gauge groups
become strong close to the same scale. A related technicolour model of Randall
which naturally includes the leptons too may also be adapted to this scenario.
We discuss the low energy constraints on the massive gauge bosons and scalars
of these models as well as their phenomenology at the TeV scale.Comment: 22 pages, 3 fig
An Interactive Approach Based on Alternative Achievement Scale and Alternative Comprehensive Scale for Multiple Attribute Decision Making under Linguistic Environment
The aim of this paper is to develop an interactive approach for multiple attribute decision making with incomplete
weight information under linguistic environment. Some of the concepts are defined, such as the distance between
two 2-tuple linguistic variables, the expectation level of alternative, the achievement scale, the alternative
comprehensive scale under linguistic environment. Based on these concepts, we establish some linear programming
models, through which the decision maker interacts with the analyst. Furthermore, we establish a practical
interactive approach for selecting the most desirable alternative(s). The interactive process can be realized by
giving and revising the achievement scale and comprehensive scale of alternatives till the achievement scale and
the comprehensive scale are achieved to the decision maker’s request. Finally, an illustrative example is also given.The author is very grateful to the associated editor and two anonymous referees for their insightful and constructive comments and suggestions that have led to an improved version of this paper. This work was partly supported by the National Natural Science Foundation of China (No. 90924027, No. 71101043), National Basic Research Program of China (973 Program, No. 2010C B951104), Key Program of National Social Science Foundation of China (No. 10AJY005), College Philosophy and Social Science Research Project of Jiangsu Province under Grant 2011SJD630007.Xu, Y.; Wang, H.; Palacios Marqués, D. (2013). An Interactive Approach Based on Alternative Achievement Scale and Alternative Comprehensive Scale for Multiple Attribute Decision Making under Linguistic Environment. International Journal of Computational Intelligence Systems. 6(1):87-95. https://doi.org/10.1080/18756891.2013.756226S87956
An Extended Technicolor Model With QCD-like Symmetry Breaking
We present a one-doublet extended technicolor model, with all fermions in
fundamental representations. The bare lagrangian has no explicit mass terms but
generates masses through gauge symmetry breaking by purely QCD-like dynamics.
The model generates three families of quarks and leptons and can accommodate
the observed third family mass spectrum (including a large top mass and light
neutrinos). In addition, we show how the model may be extended to incorporate a
top color driven top mass without the need for a strong U(1) interaction. We
discuss the compatiblity of the model with experimental constraints and its
possible predicitive power with respect to first and second family masses.Comment: 25 pages, latex, 7 figure
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