36,821 research outputs found
Hadronic form factors and the secondary production cross section: an update
Improving previous calculations, we compute the cross section using the most complete effective lagrangians available. The
new crucial ingredients are the form factors on the charm meson vertices, which
are determined from QCD sum rules calculations. Some of them became available
only very recently and the last one, needed for our present purpose, is
calculated in this work.Comment: 12 pages, 9 eps figure
Does the production asymmetry decrease at large ?
We have applied the meson cloud model (MCM) to calculate the asymmetries in
and meson production in high energy -nucleus and
-nucleus collisions. We find a good agreement with recent data. Our
results suggest that the asymmetries may decrease at large .Comment: revised version with new figures and added references to appear in
Phys. Rev. Let
Looking for meson molecules in B decays
We discuss the possibility of observing a loosely bound molecular state in a
B three-body hadronic decay. In particular we use the QCD sum rule approach to
study a molecular current. We consider an isovector-scalar
molecular current and we use the two-point and
three-point functions to study the mass and decay width of such state. We
consider the contributions of condensates up to dimension six and we work at
leading order in . We obtain a mass around 1.1 GeV, consistent with a
loosely bound state, and a decay width
around 10 MeV.Comment: 7 pages, 8 figure
Investigating the tetraquark structure of the new mesons
Using the QCD sum rule approach we investigate the possible four-quark
structure of the recently observed mesons , firstly observed
by BaBaR, X(3872), firstly observed by BELLE and observed by
BELLE. We use diquark-antidiquark currents and work in full QCD, without
relying on expansion. Our results indicate that a four-quark structure
is acceptable for these mesons.Comment: 4 pages 1 eps figure, proceedings of the XVIII Workshop on Hadronic
Interactions (RETINHA-18) Sao Paulo-S
Fermionization, Number of Families
We investigate bosonization/fermionization for free massless fermions being
equivalent to free massless bosons with the purpose of checking and correcting
the old rule by Aratyn and one of us (H.B.F.N.) for the number of boson species
relative to the number of fermion species which is required to have
bosonization possible. An important application of such a counting of degrees
of freedom relation would be to invoke restrictions on the number of families
that could be possible under the assumption, that all the fermions in nature
are the result of fermionizing a system of boson species. Since a theory of
fundamental fermions can be accused for not being properly local because of
having anticommutativity at space like distances rather than commutation as is
more physically reasonable to require, it is in fact called for to have all
fermions arising from fermionization of bosons. To make a realistic scenario
with the fermions all coming from fermionizing some bosons we should still have
at least some not fermionized bosons and we are driven towards that being a
gravitational field, that is not fermionized. Essentially we reach the
spin-charge-families theory by one of us (N.S.M.B.) with the detail that the
number of fermion components and therefore of families get determined from what
possibilities for fermionization will finally turn out to exist. The
spin-charge-family theory has long been plagued by predicting 4 families rather
than the phenomenologically more favoured 3. Unfortunately we do not yet
understand well enough the unphysical negative norm square components in the
system of bosons that can fermionize in higher dimensions because we have no
working high dimensional case of fermionization. But suspecting they involve
gauge fields with complicated unphysical state systems the corrections from
such states could putatively improve the family number prediction.Comment: 30 pages, H.B. Nielsen presented the talk at Workshop
"What Comes Beyond the Standard Models", Bled, 09-17 of July, 201
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