1,982 research outputs found
Calculations of nuclear quasi-bound states based on chiral meson-baryon amplitudes
In-medium scattering amplitudes developed within a new chirally
motivated coupled-channel model due to Cieply and Smejkal that fits the recent
SIDDHARTA kaonic hydrogen 1s level shift and width are used to construct
nuclear potentials for calculations of nuclear quasi-bound states. The
strong energy and density dependence of scattering amplitudes at and near
threshold leads to potential depths MeV.
Self-consistent calculations of all nuclear quasi-bound states, including
excited states, are reported. Model dependence, polarization effects, the role
of p-wave interactions, and two-nucleon absorption modes
are discussed. The absorption widths are comparable or even
larger than the corresponding binding energies for all nuclear
quasi-bound states, exceeding considerably the level spacing. This discourages
search for nuclear quasi-bound states in any but lightest nuclear
systems.Comment: 12 pages, 11 figure
Congruence from the Operator's Point of View: Compositionality Requirements on Process Semantics
One of the basic sanity properties of a behavioural semantics is that it
constitutes a congruence with respect to standard process operators. This issue
has been traditionally addressed by the development of rule formats for
transition system specifications that define process algebras. In this paper we
suggest a novel, orthogonal approach. Namely, we focus on a number of process
operators, and for each of them attempt to find the widest possible class of
congruences. To this end, we impose restrictions on sublanguages of
Hennessy-Milner logic, so that a semantics whose modal characterization
satisfies a given criterion is guaranteed to be a congruence with respect to
the operator in question. We investigate action prefix, alternative
composition, two restriction operators, and parallel composition.Comment: In Proceedings SOS 2010, arXiv:1008.190
Effects of the (1405) on the Structure of Multi-Antikaonic Nuclei
The effects of the (1405) () on the structure of the
multi-antikaonic nucleus (MKN), in which several mesons are embedded to
form deeply bound states, are considered based on chiral symmetry combined with
a relativistic mean-field theory. It is shown that additional attraction
resulting from the pole has a sizable contribution to not only
the density profiles for the nucleons and mesons but also the ground
state energy of the mesons and binding energy of the MKN as the number of
the embedded mesons increases.Comment: 4 pages, 3 figures, Talk presented at the 10th International
Conference on Hypernuclear and Strange Particle Physics (Hyp-X), Tokai,
Japan, Sept. 14-18, 2009. To be published in Nucl. Phys.
Charge symmetry breaking in light hypernuclei
Charge symmetry breaking (CSB) is particularly strong in the A=4 mirror
hypernuclei H--He. Recent four-body no-core shell
model calculations that confront this CSB by introducing -
mixing to leading-order chiral effective field theory hyperon-nucleon
potentials are reviewed, and a shell-model approach to CSB in p-shell
hypernuclei is outlined.Comment: presented by A. Gal at the 12th International Seminar on Nuclear
Physics, Sant'Angelo d'Ischia, May 15-19 2017; prepared for J. Phys. Conf.;
v2 -- slightly expanded versio
Zielonka's Recursive Algorithm: dull, weak and solitaire games and tighter bounds
Dull, weak and nested solitaire games are important classes of parity games,
capturing, among others, alternation-free mu-calculus and ECTL* model checking
problems. These classes can be solved in polynomial time using dedicated
algorithms. We investigate the complexity of Zielonka's Recursive algorithm for
solving these special games, showing that the algorithm runs in O(d (n + m)) on
weak games, and, somewhat surprisingly, that it requires exponential time to
solve dull games and (nested) solitaire games. For the latter classes, we
provide a family of games G, allowing us to establish a lower bound of 2^(n/3).
We show that an optimisation of Zielonka's algorithm permits solving games from
all three classes in polynomial time. Moreover, we show that there is a family
of (non-special) games M that permits us to establish a lower bound of 2^(n/3),
improving on the previous lower bound for the algorithm.Comment: In Proceedings GandALF 2013, arXiv:1307.416
Ab initio nuclear response functions for dark matter searches
We study the process of dark matter particles scattering off He with
nuclear wave functions computed using an ab initio many-body framework. We
employ realistic nuclear interactions from chiral effective field theory at
next-to-next-to-leading order (NNLO) and develop an ab initio scheme to compute
a general set of different nuclear response functions. In particular, we then
perform an accompanying uncertainty quantification on these quantities and
study error propagation to physical observables. We find a rich structure of
allowed nuclear responses with significant uncertainties for certain
spin-dependent interactions. The approach and results that are presented in
this Paper establish a new framework for nuclear structure calculations and
uncertainty quantification in the context of direct and (certain) indirect
searches for dark matter.Comment: version accepted for publication in Phys. Rev. D; figures revised
(incl. corrected labels); discussion of results extende
Strategy Derivation for Small Progress Measures
Small Progress Measures is one of the most efficient parity game solving
algorithms. The original algorithm provides the full solution (winning regions
and strategies) in
time, and requires a re-run of the algorithm on one of the winning regions. We
provide a novel operational interpretation of progress measures, and modify the
algorithm so that it derives the winning strategies for both players in one
pass. This reduces the upper bound on strategy derivation for SPM to .Comment: polished the tex
Chirally motivated K^- nuclear potentials
In-medium subthreshold KbarN scattering amplitudes calculated within a
chirally motivated meson-baryon coupled-channel model are used self
consistently to confront K^- atom data across the periodic table. Substantially
deeper K^- nuclear potentials are obtained compared to the shallow potentials
derived in some approaches from threshold amplitudes, with Re V_{chiral} =
-(85+/-5) MeV at nuclear matter density. When KbarNN contributions are
incorporated phenomenologically, a very deep K^- nuclear potential results, Re
V_{chiral+phen.} = -(180+/-5) MeV, in agreement with density dependent
potentials obtained in purely phenomenological fits to the data. Self
consistent dynamical calculations of K^- nuclear quasibound states are reported
and discussed.Comment: extended discussion, unchanged results and conclusions, accepted by
PL
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