Authors: Liu-Lin Wang, Xing-Meng Zhao, Xiao-Hai Liu, Mao-Jun Yan
Abstract:
We systematically investigate the -wave interactions between Nambu-Goldstone bosons (NGBs) and charmed mesons in the sector using the chiral unitary approach. The scattering amplitudes incorporate both the Weinberg-Tomozawa term and additional contributions from - and -channel exchanges of states predicted by the constituent quark model (CQM). Through analytic continuation of the unitarized amplitudes to the complex energy plane, we identify multiple poles corresponding to bound states and resonances. Our analysis reveals a rich spectrum of states across , and sectors, providing new insights into the nature of established resonances like and , while predicting several new states that could be observed in future experiments.# On Dispersive and Nondispersive K-matrix Formalisms
Authors: Nils Hüsken, Eric S. Swanson, Adam Szczepaniak
Abstract:
The modeling of coupled-channel effects has become increasingly important due to the availability of highly precise data for a large variety of hadronic (re)scattering processes. The K-matrix is a powerful, yet comparatively simple, method to describe scattering amplitudes, including coupled-channel effects, with the aim to interpret experimental data. Throughout the literature, a range of dispersive and nondispersive K-matrix methods are employed. Here, we compare the dispersive and nondispersive formulations in the context of the N/D method. It is shown that the methods are equivalent in the physical region under K-matrix reparameterization. Differences away from the physical region are examined. Applications to synthetic data are used to illustrate the effects of model choices concerning form factors and the application of dispersion relations, with the goal of clarifying best practices. We find no clear preference with regards to dispersive modeling. In contrast, we find that interpretational ambiguity of the bare model parameters -- and even of the form of the bare model -- is endemic, and recommend a thorough sampling of data and model spaces to assess conclusion robustness.
Authors: Feng-Kun Guo, Christoph Hanhart, Alexey Nefediev
Abstract:
Radiative decays of hadronic states provide an essential source of information that can facilitate deciphering their nature and properties. However, a lot of confusion concerning radiative decays of hadronic molecules and their interpretation can be found in the literature. In this paper, we briefly review several types of such decays and pinpoint similarities and essential differences between them. In particular, we emphasise the crucial role played by the hierarchy of the scales relevant to the studied system and the resulting necessity of employing an approach that considers them appropriately. We illustrate the situation with several instructive examples.
Authors: Qing-Yu Zhai, Dan-Yang Pang, Wen-Di Chen, O. A. Rubtsova, Rui-Rui Xu, Jun-Xu Lu, Haozhao Liang, Li-Sheng Geng
Abstract:
We revisit the neutron-deuteron scattering using the Wave-Packet Continuum Discretization (WPCD) method with the EKM chiral nuclear force at various chiral orders. We rederive the permutation operator and solve the Faddeev-AGS equations directly, without rewriting the initial Faddeev kernel and introducing pseudo-states, thereby rendering the approach easily extendable to a relativistic framework. We find that up to the next-to-next-to-next-to-leading order (NLO), although one can well describe the differential cross sections, one cannot resolve the long-standing puzzle, consistent with previous studies. The fact that the NLO chiral forces can well describe the phase shifts and the results obtained with the EKM and Idaho NLO chiral forces agree with each other underscores the need for further investigations to resolve the puzzle, e.g., considering three-body forces or relativistic effects.