arXiv subjects

A. Cieply

Publications and source records attributed to A. Cieply.

14 recordsLinked to original sources

arXiv2023

Constraining the chirally motivated $πΣ$-$\bar{K}N$ models with the $πΣ$ photoproduction mass spectra

The paper presents a first time attempt on a combined fit of the $K^{-}p$ low-energy data and the $πΣ$ photoproduction mass spectra, performed without fixing the meson-baryon rescattering amplitudes to a specific $πΣ- \bar{K}N$ coupled channels model obtained from fitting exclusively the $K^{-}p$ data. The formalism adopted to describe the photoproduction process is based on chiral perturbation theory and employs a limited number of free parameters. The achieved description of the photoproduction mass distributions is not quite satisfactory, leaving a room for improving the photo-kernel construction, but still provides additional constraints on the positions of the $Λ(1405)$ poles. In particular, the presented models tend to limit the mass of the lower pole and yield a larger width of the $\bar{K}N$ related pole at a higher mass.

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arXiv2017

Eta-mesic nuclei

In this contribution we report on theoretical studies of $η$ nuclear quasi-bound states in few- and many-body systems performed recently by the Jerusalem-Prague Collaboration [1-5]. Underlying energy-dependent $ηN$ interactions are derived from coupled-channel models that incorporate the $N^*(1535)$ resonance. The role of self-consistent treatment of the strong energy dependence of subthreshold $ηN$ amplitudes is discussed. Quite large downward energy shift together with rapid decrease of the $ηN$ amplitudes below threshold result in relatively small binding energies and widths of the calculated $η$ nuclear bound states. We argue that the subthreshold behavior of $ηN$ scattering amplitudes is crucial to conclude whether $η$ nuclear states exist, in which nuclei the $η$ meson could be bound and if the corresponding widths are small enough to allow detection of these $η$ nuclear states in experiment.

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arXiv2013

Chirally motivated separable potential model for $ηN$ amplitudes

We analyze the $ηN$ interaction using a coupled channel separable potential model that implements the chiral symmetry. The model predicts an $ηN$ stattering length $\Re a_{ηN} \approx 0.7$ fm and in-medium subthreshold attraction most likely sufficient to generate $η$-nuclear bound states. The energy dependence of the $ηN$ amplitude and pole content of the model are discussed. An idea of the same origin of the baryon resonances $N^{\star}(1535)$ and $N^{\star}(1650)$ is presented.

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arXiv2012

Chirally motivated $\bar{K}N$ amplitudes for in-medium applications

A new fit of a chirally motivated coupled-channels model for meson-baryon interactions is presented including the recent SIDDHARTA data on the 1s level characteristics of kaonic hydrogen. The kaon-nucleon amplitudes generated by the model are fully consistent with our earlier studies. We argue that a sharp increase of the real part of the in-medium $K^{-}p$ amplitude at subthreshold energies provides a link between the shallow $\bar{K}$-nuclear optical potentials obtained microscopically from threshold $\bar{K}N$ interactions and the phenomenological deep ones deduced from kaonic atoms data. The impact on the $A$-dependence of the $Λ$-hypernuclear formation rates measured in reactions with stopped kaons is discussed too.

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arXiv2011

Energy dependence of $\bar{K}N$ interaction in nuclear medium

When the $\bar{K}N$ system is submerged in nuclear medium the $\bar{K}N$ scattering amplitude and the final state branching ratios exhibit a strong energy dependence when going to energies below the $\bar{K}N$ threshold. A sharp increase of $\bar{K}N$ attraction below the $\bar{K}N$ threshold provides a link between shallow $\bar{K}$-nuclear potentials based on the chiral $\bar{K}N$ amplitude evaluated at threshold and the deep phenomenological optical potentials obtained in fits to kaonic atoms data. We show the energy dependence of the in-medium $K^{-}p$ amplitude and demonstrate the impact of energy dependent branching ratios on the $Λ$-hypernuclear production rates. \keywords{kaon-nucleon amplitude \and nuclear medium \and hypernuclei

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arXiv2010

Chiral model for $\bar{K}N$ interactions and its pole content

We use chirally motivated effective meson-baryon potentials to describe the low energy $\bar{K}N$ data including the characteristics of kaonic hydrogen. Our results are examined in comparison with other approaches based on the unitarity and dispersion relation for the inverse of the T-matrix. We demonstrate that the movements of the poles generated by the model upon varying the model parameters can serve as a tool to get additional insights on the dynamics of the strongly coupled $πΣ$-$\bar{K}N$ system.

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arXiv2010

Separable potential model for $K^{-}N$ interactions at low energies

The effective separable meson-baryon potentials are constructed to match the equivalent chiral amplitudes up to the second order in external meson momenta. We fit the model parameters (low energy constants) to the threshold and low energy $K^{-}p$ data. In the process, the $K^{-}$-proton bound state problem is solved exactly in the momentum space and the 1s level characteristics of the kaonic hydrogen are computed simultaneously with the available low energy $K^{-}p$ cross sections. The model is also used to describe the $πΣ$ mass spectrum and the energy dependence of the $K^{-}n$ amplitude.

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arXiv2010

Lambda-hypernuclear production in stopped (K-,pion) reactions reexamined

DWIA calculations of Lambda-hypernuclear production rates in stopped K- reactions on several p-shell targets used recently in experiments by the FINUDA Collaboration are reported. Chirally motivated K- + N -> pion + Lambda in-medium transition amplitudes are employed and the sensitivity of the calculated rates to the initial K- atomic wavefunctions and final pion distorted waves is studied. The calculated rates are compared with measured rates, wherever available, confirming earlier observations that (i) the calculated rates are generally lower than the measured rates, and (ii) the deeper the K- nuclear potential, the worse is the discrepancy. The A dependence of the calculated 1s Lambda hypernuclear production rates is discussed for the first time, providing a useful tool in resolving the issue of depth of the K- nuclear potential near threshold.

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arXiv2008

Kaonic hydrogen versus the $K^{-}p$ low energy data

We present an exact solution to the $K^{-}$-proton bound state problem formulated in the momentum space. The 1s level characteristics of the kaonic hydrogen are computed simultaneously with the available low energy $K^{-}p$ data. In the strong interaction sector the meson-baryon interactions are described by means of an effective (chirally motivated) separable potential and its parameters are fitted to the experimental data.

hep-ph↗

arXiv2007

Multichannel chiral approach for kaonic hydrogen

We present an exact solution to the $K^{-}$-proton bound state problem formulated in the momentum space. The 1s level characteristics of the kaonic hydrogen are described together with the available low energy $\bar{K}N$ data.

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arXiv2004

Baryonic Decays of Charmonium - a Window on Internal Baryon Structure

The baryonic decays of $J/ ψ$ provide a new way to study the internal structure of baryons. A simple diquark model applied to the calculation of the $\bar{B}B$ decay cross-sections is compared with the ordinary constituent quark model. Various models also give different predictions for the rates involving the $N^{\ast}(1440)$ resonance in the final state.

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arXiv2003

Diquark model for $J/ ψ$ baryonic decays

The baryonic decays of $J/ ψ$ provide a new way to study the internal structure of baryons. We apply a simple diquark model to the calculation of the decay cross-sections for the reactions $J/ ψ\longrightarrow \bar{p}p$, $\bar pN^*(1440)$, $\bar{N}^{\ast}N^{\ast}$, $\barΛΛ$ and $\barΣ^0Σ^0$. The results are different from those given by the ordinary constituent quark model. Hence these reactions may provide a new check of two different pictures for the baryons.

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arXiv2001

Study of chirally motivated low-energy $K^-$ optical potentials

The $K^-$ optical potential in the nuclear medium is evaluated self consistently from a free-space $K^-N$ $t$ matrix constructed within a coupled-channel chiral approach to the low-energy $\bar K N$ data. The chiral-model parameters are fitted to a select subset of the low-energy data {\it plus} the $K^-$ atomic data throughout the periodic table. The resulting attractive $K^-$ optical potentials are relatively `shallow', with central depth of the real part about 55 MeV, for a fairly reasonable reproduction of the atomic data with $χ^2 / N \approx 2.2$. Relatively `deep' attractive potentials of depth about 180 MeV, which result in other phenomenological approaches with $χ^2 / N \approx 1.5$, are ruled out within chirally motivated models. Different physical data input is required to distinguish between shallow and deep $K^-$ optical potentials. The ($K^{-}_{\rm stop},π$) reaction could provide such a test, with exclusive rates differing by over a factor of three for the two classes of potentials. Finally, forward ($K^-,p$) differential cross sections for the production of relatively narrow deeply bound $K^-$ {\it nuclear} states are evaluated for deep $K^-$ optical potentials, yielding values considerably lower than those estimated before.

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arXiv1999

$K^-$ - nucleus relativistic mean field potentials consistent with kaonic atoms

$K^-$ atomic data are used to test several models of the $K^-$ nucleus interaction. The t($ρ$)$ρ$ optical potential, due to coupled channel models incorporating the $Λ$(1405) dynamics, fails to reproduce these data. A standard relativistic mean field (RMF) potential, disregarding the $Λ$(1405) dynamics at low densities, also fails. The only successful model is a hybrid of a theoretically motivated RMF approach in the nuclear interior and a completely phenomenological density dependent potential, which respects the low density theorem in the nuclear surface region. This best-fit $K^-$ optical potential is found to be strongly attractive, with a depth of 180 \pm 20 MeV at the nuclear interior, in agreement with previous phenomenological analyses.

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