Calculations of K−K^- nuclear quasi-bound states based on chiral meson-baryon amplitudes

In-medium ${\bar K}N$ 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 $K^-$ nuclear potentials for calculations of $K^-$ nuclear quasi-bound states. The strong energy and density dependence of scattering amplitudes at and near threshold leads to $K^-$ potential depths $-Re V_K \approx 80 -120$ MeV. Self-consistent calculations of all $K^-$ nuclear quasi-bound states, including excited states, are reported. Model dependence, polarization effects, the role of p-wave interactions, and two-nucleon $K^-NN\rightarrow YN$ absorption modes are discussed. The $K^-$ absorption widths $\Gamma_K$ are comparable or even larger than the corresponding binding energies $B_K$ for all $K^-$ nuclear quasi-bound states, exceeding considerably the level spacing. This discourages search for $K^-$ 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 Λ\Lambda(1405) on the Structure of Multi-Antikaonic Nuclei

The effects of the $\Lambda$(1405) ($\Lambda^\ast$) on the structure of the multi-antikaonic nucleus (MKN), in which several $K^-$ 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 $\Lambda^\ast$ pole has a sizable contribution to not only the density profiles for the nucleons and $K^-$ mesons but also the ground state energy of the $K^-$ mesons and binding energy of the MKN as the number of the embedded $K^-$ 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 Λ\Lambda hypernuclei

Charge symmetry breaking (CSB) is particularly strong in the A=4 mirror hypernuclei $_{\Lambda}^4$H--$_{\Lambda}^4$He. Recent four-body no-core shell model calculations that confront this CSB by introducing $\Lambda$-$\Sigma^0$ mixing to leading-order chiral effective field theory hyperon-nucleon potentials are reviewed, and a shell-model approach to CSB in p-shell $\Lambda$ 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 $^{3,4}$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 $O(dm \cdot (n/\lceil d / 2 \rceil)^{\lceil d/2 \rceil})$ 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 $O(dm \cdot (n/\lfloor d / 2 \rfloor)^{\lfloor d/2 \rfloor})$.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