Hadronic resonances enhanced by thresholds

We present a neat example of a meson--baryon system where the vicinity of two different thresholds enhances the binding of a hadronic resonance, a pentaquark. As a consequence the pattern of states may change when moving among different flavor sectors, what poses a warning on naive extrapolations to heavy flavor sectors based on systematic expansions. For this purpose we simultaneously analyze the $N\bar D$ and $NB$ two-hadron systems looking for possible bound states or resonances. When a resonance is controlled by a coupled-channel effect, going to a different flavor sector may enhance or diminish the binding. This effect may, for example, generate significant differences between the charmonium and bottomonium spectra above open-flavor thresholds or pentaquark states in the open-charm and open-bottom sectors.Comment: 12 pages, 5 figures. To be published in Phys. Lett.

Too many X′sX's, Y′sY's and Z′sZ's?

A large number of new states have been reported during the last few years in charmonium spectroscopy above the charmed meson production threshold. They have been called $X's$, $Y's$, and $Z's$. We reflect on the influence of thresholds on heavy meson spectroscopy comparing different flavor sectors and quantum numbers. The validity of a quark-model picture above open-flavor thresholds would severely restrict the number of channels that may lodge meson-meson molecules.Comment: 8 pages, 5 figure

ΛNN\Lambda NN and ΣNN\Sigma NN systems at threshold: II. The effect of D waves

Using the two-body interactions obtained from a chiral constituent quark model we study all $\Lambda NN$ and $\Sigma NN$ states with I=0,1,2 and J=1/2,3/2 at threshold, taking into account all three-body configurations with S and D wave components. We constrain further the limits for the $\Lambda N$ spin-triplet scattering length a_{1/2,1}. Using the hypertriton binding energy we find a narrow interval for the possible values of the $\Lambda N$ spin-singlet scattering length a_{1/2,0}. We found that the $\Sigma NN$ system has a quasibound state in the (I,J) = (1,1/2) channel very near threshold with a width of about 2.1 MeV.Comment: 19 pages, 4 tables, 6 figures. Accepted for publication in Phys. Rev.

Unraveling the pattern of the XYZ mesons

We present a plausible mechanism for the origin of the XYZ mesons in the heavy meson spectra within a standard quark-model picture. We discuss the conditions required for the existence of four-quark bound states or resonances contributing to the heavy meson spectra, being either compact or molecular. We concentrate on charmonium and bottomonium spectra, where several new states, difficult to understand as simple quark-antiquark pairs, have been reported by different experimental collaborations. The pivotal role played by entangled meson-meson thresholds is emphasized

Problem malo tijela u kvark-modelskoj strukturi hadrona

We discuss recent results of hadron spectroscopy and hadron-hadron interaction within a quark model framework. New experimental data could be pointing out to the role played by higher-order Fock space components on low-energy observables. Our aim is to obtain a coherent description of the low-energy hadron phenomenology to constrain QCD phenomenological models and try to learn about low-energy realizations of the theory. This long-range effort is based in adapting few-body techniques to study many-quark systems.Raspravljamo nove ishode hadronske spektroskopije i međudjelovanja hadronhadron u okviru kvarkovskog modela. Novi eksperimentalni podaci možda ukazuju na ulogu Fockovih prostornih komponenti višeg reda za nisko-energijske mjerne veličine. Naš je cilj postići usklađen opis nisko-energijske hadronske fenomenologije radi probira fenomenoloških modela QCD i pokušaj da se više dozna o nisko-energijskim teorijama. Taj se dugotrajni rad zasniva na primjeni tehnika malo tijela u proučavanju sustava mnogo kvarkova

Problem malo tijela u kvark-modelskoj strukturi hadrona

We discuss recent results of hadron spectroscopy and hadron-hadron interaction within a quark model framework. New experimental data could be pointing out to the role played by higher-order Fock space components on low-energy observables. Our aim is to obtain a coherent description of the low-energy hadron phenomenology to constrain QCD phenomenological models and try to learn about low-energy realizations of the theory. This long-range effort is based in adapting few-body techniques to study many-quark systems.Raspravljamo nove ishode hadronske spektroskopije i međudjelovanja hadronhadron u okviru kvarkovskog modela. Novi eksperimentalni podaci možda ukazuju na ulogu Fockovih prostornih komponenti višeg reda za nisko-energijske mjerne veličine. Naš je cilj postići usklađen opis nisko-energijske hadronske fenomenologije radi probira fenomenoloških modela QCD i pokušaj da se više dozna o nisko-energijskim teorijama. Taj se dugotrajni rad zasniva na primjeni tehnika malo tijela u proučavanju sustava mnogo kvarkova

COVID-19 Digital Vaccination Passport Based on Blockchain with Its Own Cryptocurrency as a Reward and Mobile App for Its Use

Presented at the 4th XoveTIC Conference, A Coruña, Spain, 7–8 October 2021.[Abstract] Due to the recent outbreak of the COVID-19 pandemic, everybody’s lives have changed dramatically and society went through new stages accompanied by new needs. This article details a solution for one of these needs, since it provides a system of digital certificates for the secure storage and sharing of medical data related to COVID-19, with the goal of demonstrating immunity or lack of viral infection in a unequivocal, unbreakable and secure way. The proposed system is based on Blockchain and its inherent benefits, developing also a decentralized, mobile and multiplatform app for its use and an incentive system with a customized cryptocurrency in order to reward the users who use it