1,775 research outputs found
An inspection on the Borel masses relation used in QCD sum rules
In this work, we studied the Borel masses relation used in QCDSR
calculations. These masses are the parameters of the Borel transform used when
the three point function is calculated. We analised an usual and a more general
linear relations. We concluded that a general linear relation between these
masses provides the best results regarding the standard deviation.Comment: 6 pages, 2 figures, Prepared for 11th Hadron Physic
vertex from QCD sum rules
The form factors and the coupling constant of the vertex are
calculated using the QCD sum rules method. Three point correlation functions
are computed considering both and mesons off-shell and, after an
extrapolation of the QCDSR results, we obtain the coupling constant of the
vertex. We study the uncertainties in our result by calculating a third form
factor obtained when the is the off-shell meson, considering other
acceptable structures and computing the variations of the sum rules'
parameters. The form factors obtained have different behaviors but their
simultaneous extrapolations reach to the same value of the coupling constant
. We compare our result with other theoretical
estimates.Comment: 11 pages, 11 figure
A QCD sum rules calculation of the strong coupling constant
In this work, we calculate the form factors and the coupling constant of the
strange-charmed vertex in the framework of the QCD sum rules
by studying their three-point correlation functions. All the possible off-shell
cases are considered, , and , resulting in three different
form factors. These form factors are extrapolated to the pole of their
respective off-shell mesons, giving the same coupling constant for the process.
Our final result for the coupling constant is .Comment: 17 pages, 4 figure
Violation and persistence of the K-quantum number in warm rotating nuclei
The validity of the K-quantum number in rapidly rotating warm nuclei is
investigated as a function of thermal excitation energy U and angular momentum
I, for the rare-earth nucleus 163Er. The quantal eigenstates are described with
a shell model which combines a cranked Nilsson mean-field and a residual
two-body interaction, together with a term which takes into account the angular
momentum carried by the K-quantum number in an approximate way. K-mixing is
produced by the interplay of the Coriolis interaction and the residual
interaction; it is weak in the region of the discrete rotational bands (U
\lesim 1MeV), but it gradually increases until the limit of complete violation
of the K-quantum number is approached around U \sim 2 - 2.5 MeV. The calculated
matrix elements between bands having different K-quantum numbers decrease
exponentially as a function of , in qualitative agreement with recent
data.Comment: 29 pages, 7 figure
Coupling of Transport and Chemical Processes in Catalytic Combustion
Catalytic combustors have demonstrated the ability to operate efficiently over a much wider range of fuel air ratios than are imposed by the flammability limits of conventional combustors. Extensive commercial use however needs the following: (1) the design of a catalyst with low ignition temperature and high temperature stability, (2) reducing fatigue due to thermal stresses during transient operation, and (3) the development of mathematical models that can be used as design optimization tools to isolate promising operating ranges for the numerous operating parameters. The current program of research involves the development of a two dimensional transient catalytic combustion model and the development of a new catalyst with low temperature light-off and high temperature stablity characteristics
The B_{s0} meson and the B_{s0}B K coupling from QCD sum rules
We evaluate the mass of the scalar meson and the coupling constant
in the vertex in the framework of QCD sum rules. We consider the
as a tetraquark state to evaluate its mass. We get m_{B_s0}=(6.04\pm
0.08) \GeV, which is bigger than predictions supposing it as a
state or a bound state with . To evaluate the coupling we use the three point correlation functions of the vertex,
considering as a normal state. The obtained coupling
constant is: g_{B_{s0} B K} =(16.3 \pm 3.2) \GeV. This number is in agreement
with light-cone QCD sum rules calculation. We have also compared the decay
width of the \BS\to BK process considering the \BS to be a state
and a molecular state. The width obtained for the molecular state is
twice as big as the width obtained for the state. Therefore, we
conclude that with the knowledge of the mass and the decay width of the \BS
meson, one can discriminate between the different theoretical proposals for its
structure.Comment: revised version to appear in Phys. Rev.
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