54 research outputs found
Power Counting and Wilsonian Renormalization in Nuclear Effective Field Theory
Effective field theories are the most general tool for the description of low
energy phenomena. They are universal and systematic: they can be formulated for
any low energy systems we can think of and offer a clear guide on how to
calculate predictions with reliable error estimates, a feature that is called
power counting. These properties can be easily understood in Wilsonian
renormalization, in which effective field theories are the low energy
renormalization group evolution of a more fundamental ---perhaps unknown or
unsolvable--- high energy theory. In nuclear physics they provide the
possibility of a theoretically sound derivation of nuclear forces without
having to solve quantum chromodynamics explicitly. However there is the problem
of how to organize calculations within nuclear effective field theory: the
traditional knowledge about power counting is perturbative but nuclear physics
is not. Yet power counting can be derived in Wilsonian renormalization and
there is already a fairly good understanding of how to apply these ideas to
non-perturbative phenomena and in particular to nuclear physics. Here we review
a few of these ideas, explain power counting in two-nucleon scattering and
reactions with external probes and hint at how to extend the present analysis
beyond the two-body problem.Comment: Contribution to the IJMPE special issue on "Effective Field Theories
in Nuclear Physics". This update includes the corrections and changes of the
published versio
Heavy hadron molecules in effective field theory: the emergence of exotic nuclear landscapes
Heavy hadron molecules were first theorized from a crude analogy with the
deuteron and the nuclear forces binding it, a conjecture which was proven to be
on the right track after the discovery of the . However, this analogy
with nuclear physics has not been seriously exploited beyond a few calculations
in the two- and three-body sectors, leaving a great number of possible
theoretical consequences unexplored. Here we show that nuclear and heavy hadron
effective field theories are formally identical: using a suitable notation,
there is no formal difference between these two effective field theories. For
this, instead of using the standard heavy superfield notation, we have written
the heavy hadron interactions directly in terms of the light quark degrees of
freedom. We give a few examples of how to exploit this analogy, e.g. the
calculation of the two-pion exchange diagrams. Yet the most relevant
application of the present idea is the conjecture of exotic nuclear landscapes,
i.e. the possibility of few heavy hadron bound states with characteristics
similar to those of the standard nuclei.Comment: Prepared for the special issue of "The tower of effective (field)
theories and the emergence of nuclear phenomena"; 14 pages, 3 tables and 2
figures; corresponds with published versio
Heavy Baryon-Antibaryon Molecules in Effective Field Theory
We discuss the effective field theory description of bound states composed of
a heavy baryon and antibaryon. This framework is a variation of the ones
already developed for heavy meson-antimeson states to describe the or
the and resonances. We consider the case of heavy baryons for which
the light quark pair is in S-wave and we explore how heavy quark spin symmetry
constrains the heavy baryon-antibaryon potential. The one pion exchange
potential mediates the low energy dynamics of this system. We determine the
relative importance of pion exchanges, in particular the tensor force. We find
that in general pion exchanges are probably non-perturbative for the , and
systems, while for the , and
cases they are perturbative If we assume that the
contact-range couplings of the effective field theory are saturated by the
exchange of vector mesons, we can estimate for which quantum numbers it is more
probable to find a heavy baryonium state. The most probable candidates to form
bound states are the isoscalar , , and
and the isovector and
systems, both in the hidden-charm and hidden-bottom sectors. Their
doubly-charmed and -bottom counterparts (, , ) are also good candidates
for binding.Comment: 38 pages, 1 figure, 12 tables; extended discussion on the most
probable molecular heavy baryon-antibaryon states to bind; corresponds to
published versio
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