Search

In view of the recent discovery of $T_{cc}$, which can be described as a $DD^*$ molecular state, we perform a study of the $KDD^*$ system, and its extension to studying $KD^*D^*$, where $D^*D^*$ is bound as a spin 1 $T_{cc}$-like state, to search for the possible existence of exotic mesons with the open flavors $ccs$ being part of their quark configuration. Considering the additional attractive interactions present in the $KD$ and $KD^*$ subsystems, where the states $D^*_{s0}(2317)$ and $D_{s1}(2460)$ are generated, we solve the Faddeev equations considering the fixed-center approximation for the mentioned three-body systems and find the existence of two doubly charmed $K^*$-like mesons, $K_{cc}^*(4309)$ and $K_{cc}^*(4449)$, with quantum numbers $I(J^P)=1/2\,(1^-)$. Considering the respective three-body thresholds of the two systems, both $K_{cc}$-states are bound by around $60$ MeV. An experimental confirmation will bring evidence for the existence of a degree of exoticity beyond charm +2., Comment: 8 pages, 5 figures, 1 table

The femtoscopic $\phi N$ correlation function is studied within a hadronic effective Lagrangian approach with coupled channels, based on hidden local symmetry. The results are compared with the data recently reported by the ALICE collaboration. We find that the correlation function has very different features for the $\phi N$ system in the spin 1/2 and 3/2 configurations, with the spin-averaged combination matching well with the experimental data. A strong attraction, leading to the formation of a $\phi N$ bound state or a very prominent cusp is found in the spin 3/2 case. The correlation function for spin 1/2, on the other hand, is strongly impacted by the negative parity $N^*(1895)$ nucleon resonance., Comment: Updated version with some typos corrected and new references added

We discuss that some light baryon resonances exhibit properties which cannot be described when attributing a three-valence quark structure to them. Besides pointing out the hadron resonances which clearly require description beyond the quark model, we focus on the third $s_{11},~ N^*$ state and its decay to final states consisting of the lightest hyperon resonances which have a partial width comparable to that for the decay to $\pi N$. Such properties of the mentioned nucleon resonance get manifested in the cross sections and other observables related to processes producing the lightest hyperon resonances. We show that all these findings arise from the strong association of the baryon resonances to the dynamics among the ground-state hadrons., Comment: Proceedings for the XLV Symposium on Nuclear Physics, held in Cocoyoc, Morelos, Mexico

We summarize the results we obtained for the partial decay widths of $\phi(2170)$ into two-body final states formed by a $\bar K$ and a Kaonic resonance, like $K(1460)$, $K_1(1270)$, as well as to final states constituted by a $\phi$ and an $\eta/\eta^\prime$ mesons. The results obtained are compared with the values extracted from experimental data on the corresponding branching ratios, which were determined by the BESIII collaboration. A reasonable agreement is found, which together with the previous reproduction of the mass, width, and cross section for the process $e^+ e^-\to \phi f_0$ strongly indicates the molecular nature of $\phi(2170)$ as a $\phi K\bar K$ system., Comment: Contribution to the proceedings of the XLV Symposium on Nuclear Physics, 8-11 January 2024, M\'exico

In view of the renewing experimental interest for searching strangeness $+1$ baryons at J-PARC, we study the existence of light baryon resonances with strangeness +1 generated in the $K$-$(N^*/\Delta^*)$ system, where $N^*$ represents either $N^*(1535)$/$N^*(1650)$/$N^*(1700)$, and $\Delta^*$ corresponds to $\Delta(1620)$. The description of the properties of the aforementioned states requires considering the dynamics involved in the coupled pseudoscalar-baryon and vector-baryon systems with strangeness $S=0$ in the s-wave. For the purpose of our current study, we consider the pseudoscalar-baryon (PB) and vector-baryon channels (VB) to which the mentioned $N^*$ and $\Delta^*$ resonances couple and solve the Faddeev equations for the coupled channel system $K$-$\text{PB}$, $K$-$\text{VB}$, with all interactions being in the s-wave. Despite some strong attraction present in two of the subsystems, we do not find clear evidence supporting the formation of strangeness +1 states, with spin-parity $J^P=1/2^+$, in the energy region $2000-2200$ MeV. However, the case of spin-parity $J^P=3/2^+$ seems more promising, showing the formation of a resonance with a mass around 2167 MeV, with a width of 90-100 MeV. We suggest that a signal of such a state could be found in processes with final states like $KN$, $K^*(892) N$.

We present a coupled channel treatment of meson-meson dynamics, for systems with spin-parity $1^+$, and determine the corresponding amplitudes by solving the Bethe-Salpeter equations, which lead to the generation of two axial resonances when mesons are considered as the degrees of freedom in the model. One of them is narrow and has properties in good agreement with those of $D_1(2420)$. The other pole is wider, but its real and imaginary parts do not match well with the mass and width of $D_1(2430)$. The situation improves when a bare quark-model state is included, indicating that the dynamics at the quark level as well as among hadrons can describe the two states simultaneously. Further, we discuss that there exists a divergence in the value of the $D^*\pi$ scattering length determined through data coming from lattice QCD calculations and from heavy ion collisions. Such different values can be accommodated in the model by making small changes in the parameters while producing two poles having properties compatible with the two lightest $D_1$ states. With these results, we proceed to calculate the correlation function for the $D^{*+(0)}\pi^{0(+)}$ system for different sizes of the source. We discuss which scenarios can be useful to shed some light on the issue., Comment: Version accepted for publication

Leading $\Lambda$ (LL) production in $ep$ collisions at high energies is investigated using the color dipole formalism and taking into account the nonlinear QCD effects. In particular, the impact of the absorptive effects on the LL spectra are estimated considering the kinematical range that will be probed by the Electron Ion Collider (EIC) and by the Large Hadron electron Collider (LHeC). Our results indicate that the LL spectrum is strongly suppressed at small photon virtualities. These results suggest that absorptive effects are not negligible and should be taken into account in order to extract the kaon structure function from data on leading $\Lambda$ production., Comment: 9 pages, 5 figures. arXiv admin note: substantial text overlap with arXiv:2011.09515

In this work we calculate the decay widths of $\phi(2170)$ to $\phi\eta$ and $\phi\eta^\prime$ by considering $\phi(2170)$ as a $\phi K\bar K$ state, with $K\bar K$ clustering as $f_0(980)$. These decay widths have been recently determined by the BESIII, BaBar and Belle collaborations with the aim of unraveling the nature of $\phi(2170)$. By analyzing the data on the cross sections of the process $e^+e^-\to\phi\eta$, two solutions were found by the BESIII collaboration with the same $\chi^2/n.d.f$, mass and width for $\phi(2170)$. However, different values for $\mathcal{B}^{\phi(2170)}_{\phi\eta}\Gamma^{\phi(2170)}_{e^+e^-}$ were obtained: $0.24^{+0.12}_{-0.07}$ eV (solution I) and $10.11^{+3.87}_{-3.13}$ eV (solution II). In case of $\mathcal{B}^{\phi(2170)}_{\phi\eta^\prime}\Gamma^{\phi(2170)}_{e^+e^-}$, a value of $7.1\pm 0.7\pm 0.7$ was determined by the BESIII collaboration from fits to the data on the cross section of $e^+e^-\to\phi\eta^\prime$. The Belle collaboration has also determined $\mathcal{B}^{\phi(2170)}_{\phi\eta}\Gamma^{\phi(2170)}_{e^+e^-}$ more recently, although the statistical significance related to the signal of $\phi(2170)$ in the data is low. We calculate the decay widths of $\phi(2170)$ to $\phi\eta$ and $\phi\eta^\prime$, and compare their ratio $\Gamma^{\phi(2170)}_{\phi \eta}/\Gamma^{\phi(2170)}_{\phi \eta^\prime}$ with the one determined by using the above mentioned experimental data. Considering the theoretical and experimental uncertainties, the lower limit of our theoretical result ($\simeq 2.6$) is close to the upper value obtained ($\simeq 2$) by using the solution II of BESIII for $\mathcal{B}^{\phi(2170)}_{\phi\eta}\Gamma^{\phi(2170)}_{e^+e^-}$, as well as to the upper limit found ($\simeq 2.8$) when considering the solutions III and IV of the Belle collaboration for $\mathcal{B}^{\phi(2170)}_{\phi\eta}\Gamma^{\phi(2170)}_{e^+e^-}$., Comment: Published version; new calculations added

We consider different phase spaces for the Toda flows and the less familiar SVD flows. For the Toda flow, we handle symmetric and non-symmetric matrices with real simple eigenvalues, possibly with a given profile. Profiles encode, for example, band matrices and Hessenberg matrices. For the SVD flow, we assume simplicity of the singular values. In all cases, an open cover is constructed, as are corresponding charts to Euclidean space. The charts linearize the flows, converting it into a linear differential system with constant coefficients and diagonal matrix. A variant construction transform the flows into uniform straight line motion. Since limit points belong to the phase space, asymptotic behavior becomes a local issue. The constructions rely only on basic facts of linear algebra, making no use of symplectic geometry., Comment: 25 pages, 2 figures

In this work we present an attempt to describe the $X_1(2900)$ found by the LHCb collaboration, in the experimental data on the invariant mass spectrum of $ D^-K^+$, as a three-meson molecular state of the $K\rho\bar D$ system. We discuss that the interactions in all the subsystems are attractive in nature, with the $\rho \bar D$ interaction generating $\bar D_1(2420)$ and the $K \rho$ resonating as $K_1(1270)$. We find that the system can form a three-body state but with a mass higher than that of $X_1(2900)$. We investigate the $K \rho D$ system too, finding that the three-body dynamics generates an isoscalar state, which can be related to $D_{s1}^*(2860)$, and an exotic isovector state. This latter state has a mass similar to that of the $X_0(2900)$ and $X_1(2900)$ states found by LHCb, but a very small width ($\sim 7.4 \pm 0.9$ MeV) and necessarily requires more than two quarks to describe its properties. We hope that our findings will encourage experimental investigations of the isovector $K \rho D$ state. Finally, in the pursuit of finding a description for $X_1(2900)$, we study the $\pi\bar K^* D^*$ system where $ \bar K^*D^*$ forms $0^+$, $1^+$ and $2^+$ states. We do not find a state which can be associated with $X_1(2900)$.

In this work, we outline the findings of our recent study of the properties of $N^*(1895)$ and its consequential impacts on the cross sections of the photoproduction of $\Lambda(1405)$. Further, we discuss the possibility of the existence of an isovector state, with the mass similar to $\Lambda(1405)$, which we refer to as $\Sigma(1400)$. With the idea of motivating experimental investigations of $\Sigma(1400)$, we have studied its photoproduction process and determined the respective cross sections and polarization observables. We have studied also the coupling of $N^*(1895)$ to $K\Sigma(1400)$ and found that it gives an important contribution to the cross sections near the threshold. In the process, we have determined the branching ratios of the decay of $N^*(1895)$, to the final states involving $\Lambda(1405)$ and $\Sigma(1400)$, to be in the range of 6-7 MeV. Our findings can motivate consideration of alternative processes in partial wave analyses of experimental data, when studying the properties of $N^*(1895)$., Comment: Proceedings for the 4th Jagiellonian Symposium on Advances in Particle Physics and Medicine, organised by the Jagiellonian University in Krakow, with the address and acknowledgments updated for one of the authors

In these proceedings we present our recent results on the study of the process $\gamma d \to \pi^0 \eta d$, where the existence of a dibaryon in the $\eta d$ invariant mass distribution has been recently claimed. As we will show, many of the relevant aspects observed in the experiment, as the shift of the $\eta d$ and $\pi d$ invariant mass distributions with respect to phase space can be described with our model, where no dibaryon is formed. Instead, we consider the interaction of the $\gamma$ with the nucleons forming the deuteron to proceed through $\gamma N \to \Delta(1700)\to \eta \Delta(1232) \to \eta \pi^0 N$, followed by the rescattering of the $\pi$ and $\eta$ with the other nucleon of the deuteron. Theoretical uncertainties related to different parameterizations of the deuteron wave function are investigated, Comment: Contribution to the proceedings of the 4th Jagiellonian Symposium on Advances in Particle Physics and Medicine, 10-15 July 2022. arXiv admin note: text overlap with arXiv:2205.00948

In this work we investigate the possibility of the formation of states from the dynamics involved in the $D^*D^*D^*$ system by considering that two $D^*$'s generate a $J^P=1^+$ bound state, with isospin 0, which has been predicted in an earlier theoretical work. We solve the Faddeev equations for this system within the fixed center approximation and find the existence of $J^P=0^-$, $1^-$ and $2^-$ states with charm $3$, isospin $1/2$, masses $\sim 6000$ MeV, which are manifestly exotic hadrons, i.e., with a multiquark inner structure.

In this talk we present a summary of our latest results on the investigation of three-body systems with explicit/hidden charm and with explicit/hidden strangeness. To be more concrete, in case of explicit strangeness quantum number, we pay attention on the $K D D $ and $K D\bar D^*$ systems, where, in the former, a charm $+2$, isospin $1/2$ and strangeness $+1$ state is obtained with a mass around 4140 MeV, while in the latter, a $K^*$ state, with hidden charm, and a mass close to 4307 MeV is found. In case of hidden strangeness, the $DK\bar K$ system is studied, while in the hidden charm and no strangeness quantum numbers sector, the $ND\bar D^*$ system is investigated. In the former a meson $D$ with mass around 2900 MeV is found to be generated, while in the latter several $N^*$ and $\Delta^*$ states with hidden charm are obtained with masses about $4600$ MeV. All these states constitute predictions of our model and future experimental confirmation of them would be relevant to elucidate the properties of the strong interaction in the presence of heavy quarks., Comment: XV International Workshop on Hadron Physics (XV Hadron Physics), 13 -17 September 2021, S\~ao Jos\'e dos Campos, Brazil

We have done a theoretical study of the $\gamma d \to \pi^0 \eta d$ reaction starting with a realistic model for the $\gamma N \to \pi^0 \eta N$ reaction that reproduces cross sections and polarization observables at low energies and involves the $\gamma N \to \Delta(1700)\to \eta \Delta(1232) \to \eta \pi^0 N$ process. For the coherent reaction in the deuteron we considered the impulse approximation together with the rescattering of the pions and the $\eta$ on a different nucleon than the one where they are produced. We found this second mechanism very important since it helps share between two nucleons the otherwise large momentum transfer of the reaction. Other contributions to the $\gamma d\to\pi^0\eta d$ reaction, involving the $\gamma N\to \pi^\pm\pi^0 N^\prime$ process, followed by the rescattering of the $\pi^\pm$ with another nucleon to give $\eta$ and a nucleon, have also been included. We find a natural explanation, tied to the dynamics of our model, for the shift of the $\eta-d$ mass distribution to lower invariant masses, and of the $\pi^0-d$ mass distribution to larger invariant masses, compared to a phase space calculation. We also study theoretical uncertainties related to the large momenta of the deuteron wave function involved in the process as well as to the couplings present in the model. Striking differences are found with the experimental angular distribution and further theoretical investigations might be necessary., Comment: Published version

We prove that a Poisson structure on a projective toric variety which is invariant by the torus action and whose symplectic leaves are the torus orbits is not exact. This is deduced from a geometric criterion for non-exactness of Poisson structures with a finite number of symplectic leaves.

In this talk I review the findings of our recent works where we have studied the decay of $N^*(1895)$ and the implications of such properties on the photoproduction of light hyperons. I discuss that meson-baryon interactions play an essential role in describing the nature of $N^*(1895)$ and report the details of our investigation of its decays to different meson-baryon systems and to final states involving $\Lambda(1405)$ and a proposed $\Sigma(1400)$. We find that the width of $N^*(1895)$ gets important contributions from the decay to light hyperon resonances. Such an information can be used to look for alternative processes to study $N^*(1895)$ in experimental data., Comment: Hadron 2021 conference proceedings

We study the interaction of the doubly bottom systems $BB$, $B^* B$, $B_s B$, $B_s^* B$, $B^* B^*$, $B^* B_s$, $B^*B_s^*$, $B_s B_s$, $B_s B_s^*$, $B_s^* B_s^*$ by means of vector meson exchange with Lagrangians from an extension of the local hidden gauge approach. The full s-wave scattering matrix is obtained implementing unitarity in coupled channels by means of the Bethe-Salpeter equation. We find poles below the channel thresholds for the attractively interacting channels $B^* B$ in $I=0$, $B^*_s B-B^*B_s$ in $I=\frac{1}{2}$, $B^* B^*$ in $I=0$, and $B^*_s B^*$ in $I=\frac{1}{2}$, all of them with $J^P=1^+$. For these cases the widths are evaluated identifyng the dominant source of imaginary part. We find binding energies of the order of $10-20$ MeV, and the widths vary much from one system to the other: of the order of 10-100 eV for the $B^* B$ system and $B^*_s B-B^*B_s$, about $6$ MeV for the $B^* B^*$ system and of the order of $0.5$ MeV for the $B^*_s B^*$ system., Comment: 23 pages, 10 figures

In this talk we discuss the formation of exotic hadrons with hidden charm arising from three-body interactions. To be more specific, in the strangeness sector, we predict the existence of a mesonic state, $K^*(4307)$, which is dynamically generated from the three-body interactions of the $KD\bar{D}^*$ system, has mass around $4307$ MeV and quantum numbers $I(J^P) = 1/2\,(1^-)$. In the baryonic sector, we predict the existence of $N^*$ states, which are generated from the three-body interactions of the $ND\bar{D}^*$ system, with masses around $4400\sim 4600$ MeV, widths of $2\sim 20$ MeV and positive parity., Comment: Proceedings HADRON 2021

In this talk we show our recent results on the decay widths of $\phi(2170)$ to final states formed by an anti-Kaon and a Kaonic resonance, in particular, $K(1460)$, $K_1(1270)$ and $K_1(1400)$, considering a molecular description for $\phi(2170)$. Branching fraction ratios are obtained and compared with the recent results found by the BESIII collaboration, finding compatible results., Comment: Proceedings prepared for HADRON2021

We study the decay properties of a $D(2900)$ state, with spin-parity $0^-$, whose existence was proposed in an earlier study of the $D K\bar K$ and coupled channel system. It was found in the former work that a $D$-meson appears with a mass of about 2900 MeV from the three-body dynamics while the charmless subsystem of the pseudoscalar mesons forms the $f_0(980)$ resonance. Motivated by the recent experimental investigations of $D$-mesons around 3000 MeV, we now study the two-body decays of $D(2900)$. We find that the nature of the said state sets the main decay channels to be $D^*\pi$, $D^{*}_s \bar K$ and $D^*_{s0}(2317)\bar K$. It turns out that decay width to the last one is the largest, making the $D^*_{s0}(2317)\bar K$ system to be the most favorable one to look for a signal of $D(2900)$. We compare the decay properties of our state with those of the $D$-meson states, proposed within quark models, near 3000 MeV. We hope that our findings and discussions can be useful for the future experimental investigations of charm mesons around 3000 MeV.

We discuss a system of third order PDEs for strictly convex smooth functions on domains of Euclidean space. We argue that it may be understood as a closure of sorts of the first order prolongation of a family of second order PDEs. We describe explicitly its real analytic solutions and all the solutions which satisfy a genericity condition; we also describe a family of non-generic solutions which has an application to Poisson geometry and Kahler structures on toric varieties. Our methods are geometric: we use the theory of Hessian metrics and symmetric spaces to link the analysis of the system of PDEs with properties of the manifold of matrices with orthogonal columns.

This work presents twelve fine-tuned deep learning architectures to solve the bacterial classification problem over the Digital Image of Bacterial Species Dataset. The base architectures were mainly published as mobile or efficient solutions to the ImageNet challenge, and all experiments presented in this work consisted of making several modifications to the original designs, in order to make them able to solve the bacterial classification problem by using fine-tuning and transfer learning techniques. This work also proposes a novel data augmentation technique for this dataset, which is based on the idea of artificial zooming, strongly increasing the performance of every tested architecture, even doubling it in some cases. In order to get robust and complete evaluations, all experiments were performed with 10-fold cross-validation and evaluated with five different metrics: top-1 and top-5 accuracy, precision, recall, and F1 score. This paper presents a complete comparison of the twelve different architectures, cross-validated with the original and the augmented version of the dataset, the results are also compared with several literature methods. Overall, eight of the eleven architectures surpassed the 0.95 scores in top-1 accuracy with our data augmentation method, being 0.9738 the highest top-1 accuracy. The impact of the data augmentation technique is reported with relative improvement scores., Comment: 22 pages, 2 figures, 5 tables. Submitted to Multimedia Tools and Applications, issue 1218 - Engineering Tools and Applications in Medical Imaging (currently in reviewing process)

In this work we study the formation of $N^*$'s as a consequence of the dynamics involved in the $ND\bar D^*-N\bar D D^*$ system when the $D\bar D^*-\bar D D^*$ subsystem generates $X(3872)$ in isospin 0 and $Z_c(3900)$ in isospin 1. States with isospin $I=1/2$ and mass in the energy region $4400-4600$ MeV are found to arise with spin-parity $J^P=1/2^+$ and $3/2^+$, leading to predictions in this way of the existence of $N^*$ resonances with hidden charm and a three-body nature. We also discuss the possibility of the existence of $\Delta_c$ states, i.e., $\Delta$'s with hidden charm., Comment: Published version

We study the photoproduction of the $\Lambda(1405)$ and $\Sigma(1400)$ hyperon resonances, the latter of which is not a well established state. We evaluate the $s$-, $t$- and $u$-channel diagrams in the Born approximation by employing the effective Lagrangians. A new ingredient is the inclusion of a nucleon resonance $N^*(1895)$ that is dynamically generated with predictions for its coupling to the $K\Lambda(1405)$ and $K\Sigma(1400)$ channels. To extend the applicability of the model to energies beyond the threshold region, we consider a Regge model for the $t$-channel $K$- and $K^*$-exchanges. Our results are in good agreement with the CLAS data available on $\Lambda(1405)$, while for $\Sigma(1400)$ we predict observables for its production. We also provide polarization observables for both hyperon productions, which can be useful in future experimental investigations. The present study provides new information on the nucleon resonance $N^*(1895)$ which can be an alternative source for generating the hyperon resonances $\Lambda(1405)$ and $\Sigma(1400)$., Comment: 13 pages, 9 figures

In this work we study the strong decays of $\phi(2170)$ to final states involving the kaonic resonances $K(1460)$, $K_1(1270)$ and $K_1(1400)$, on which experimental data have recently been extracted by the BESIII Collaboration. The formalism developed here is based on interpreting $\phi(2170)$ and $K(1460)$ as states arising from three-hadron dynamics, which is inspired by our earlier works. For $K_1(1270)$ and $K_1(1400)$ we investigate different descriptions, such as a mixture of states belonging to the nonet of axial resonances, or the former one as a state originating from the vector-pseudoscalar dynamics. The ratios among the partial widths of $K^+(1460)K^-$, $K^+_1(1400)K^-$ and $K^+_1(1270)K^-$ obtained are compatible with the experimental results, reinforcing the three-body nature of $\phi(2170)$. Within our formalism, we can also explain the suppressed decay of $\phi(2170)$ to $K^*(892) \bar K^*(892)$, as found by the BESIII Collaboration. Furthermore, our results can be useful in clarifying the properties of $K(1460)$, $K_1(1270)$ and $K_1(1400)$ when higher statistics data would be available.

We analyze \emph{submersions with Poisson fibres}. These are submersions whose total space carries a Poisson structure, on which the ambient Poisson structure pulls back, as a Dirac structure, to Poisson structures on each individual fibre. Our ``Poisson-Dirac viewpoint'' is prompted by natural examples of Poisson submersions with Poisson fibers -- in toric geometry and Poisson-Lie groups -- whose analysis was not possible using the existing tools in the Poisson literature. The first part of the paper studies the Poisson-Dirac perspective of inducing Poisson structures on submanifolds. This is a rich landscape, in which subtle behaviours abound -- as illustrated by a surprising ``jumping phenomenon'' concerning the complex relation between the induced and the ambient symplectic foliations, which we discovered here. These pathologies, however, are absent from the well-behaved and abundant class of \emph{coregular} submanifolds, with which we are mostly concerned here. The second part of the paper studies Poisson submersions with Poisson fibres -- the natural Poisson generalization of flat symplectic bundles. These Poisson submersions have coregular Poisson-Dirac fibres, and behave functorially with respect to such submanifolds. We discuss the subtle collective behavior of the Poisson fibers of such Poisson fibrations, and explain their relation to pencils of Poisson structures. The third and final part applies the theory developed to Poisson submersions with Poisson fibres which arise in Lie theory. We also show that such submersions are a convenient setting for the associated bundle construction, and we illustrate this by producing new Poisson structures with a finite number of symplectic leaves. Some of the points in the paper being fairly new, we illustrate the many fine issues that appear with an abundance of (counter-)examples., Comment: To appear in Revista Matematica Iberoamericana

The nature of nucleon resonances is still being debated, while much experimental data are accumulated. In this work, we focus on the negative parity resonance $N^*(1895)$ which is located in the scattering region of various meson-baryon coupled channels, and such dynamics can be crucial in understanding its properties. To test the relevance of such hadron dynamics, we investigate the decay properties of $N^*(1895)$ in detail. We examine how a two pole nature of $N^*(1895)$ is compatible with its observed decay properties. Moreover, we find that the resonance decays into final states involving $\Lambda(1405)$ and $\Sigma(1400)$, where the latter is not yet observed experimentally. Such decay processes can be useful to study the properties of the aforementioned hyperon resonances.

We present a work which is meant to inspire the few-body practitioners to venture into the study of new, more exotic, systems and to hadron physicists, working mostly on two-body problems, to move in the direction of studying related few-body systems. For this purpose we devote the discussions in the introduction to show how the input two-body amplitudes can be easily obtained using techniques of the chiral unitary theory, or its extensions to the heavy quark sector. We then briefly explain how these amplitudes can be used to solve the Faddeev equations or a simpler version obtained by treating the three-body scattering as that of a particle on a fixed center. Further, we give some examples of the results obtained by studying systems involving mesons. We have also addressed the field of many meson systems, which is currently almost unexplored, but for which we envisage a bright future. Finally, we give a complete list of works dealing with unconventional few-body systems involving one or several mesons, summarizing in this way the findings on the topic, and providing a motivation for those willing to investigate such systems., Comment: paper commissioned for the special issue "New Trends in Hadron Physics: a Few-Body Perspective" of Few Body Systems

This paper describes two real analytic symplectomorphisms defined on appropriate dense open subsets of any coadjoint orbit of a compact semisimple Lie algebra. The first symplectomorphism sends the open dense subset to a bounded subset of a standard cotangent bundle. The second symplectomorphism has target a bounded subset of a hyperbolic coadjoint orbit of an associated non-compact semi-simple Lie algebra. Therefore, coadjoint orbits of compact Lie algebras are symplectic compactifications of domains of cotangent bundles, and are in symplectic duality with hyperbolic orbits of non-compact semisimple Lie algebras., Comment: Cross-reference and typos corrected

We report on a robust prediction of heavy $K^*$ meson by solving the Faddeev equations with fixed-center approximation for the three-body $KD\bar{D}^*$ system. As the excited Kaon state, $K^*$ is an exotic hidden charm meson with $M-i\Gamma/2=4307\pm2-i9\pm2$ MeV and $I(J^P)=1/2(1^-)$. We further performed the evaluation of the decay width of $K^*(4307)$ to the open two-body channels. We expect that the above findings inspire an experimental investigation of this exotic $K^*$ meson and to study the so far unexplored heavy strange meson sector., Comment: Proceeding Hadron 2019, Guilin, China, 16-21 August 2019

In this work we extend our formalism to study meson-baryon interactions by including $s$- and $u$-channel diagrams for pseudoscalar-baryon systems. We study the coupled systems with strangeness $-1$ and focus on studying the isospin-1 resonance(s), especially in the energy region around 1400 MeV. By constraining the model parameters to fit the cross section data available on several processes involving relevant channels, we find resonances in the isoscalar as well as the isovector sector in the energy region around 1400 MeV., Comment: Contribution to the Hadron 2019 conference proceedings

In this work we study the production of $K^*(4307)$ in $B$ decays by determining the $J/\psi\pi^{+(0)}K^{0}$ and $J/\psi \pi^- K^+$ invariant mass distributions of the processes $B^+\to J/\psi \pi^+\pi^0 K^0$ and $B^+\to J/\psi \pi^+\pi^- K^+$, respectively. Such $K^*(4307)$ has been recently predicted as a three-body state originated from the dynamics involved in the $K D\bar D^*$ system, with the $KD$ subsystem forming the $D^{*}_{s0}(2317)$ in isospin 0, and the $D\bar D^*$ subsystem generating the $X(3872)$ in isospin 0 and the $Z_c(3900)$ in isospin 1. The hidden charm content of $K^*(4307)$ favors its decay to a state like $J/\psi\pi K$ and the study of $B$-decays with these particles in their final states can constitute a way of finding experimental evidences for such an exotic vector meson, whose width, in spite of its large mass, is still quite narrow (around 18 MeV).

In this talk we summarize our latest results on the study of three-body systems with explicit/hidden charm and with strangeness. In particular, we focus on the $K D D $ and $K D\bar D^*$ systems, where a charm $+2$, isospin $1/2$ and strangeness $+1$ state is found with a mass around 4140 MeV in the former and a $K^*$ state, with hidden charm, at a mass around 4307 MeV is obtained in the latter. Both states are predictions of our model and the experimental confirmation of them would be important to understand the properties of the strong interaction in the presence of heavy quarks., Comment: Proceeding Hadron 2019, Guilin, China, 16-21 August 2019

Nowadays, it is generally accepted that the $DK$ interaction in isospin zero is strongly attractive and the $D_{s0}^*(2317)$ can be described as a $DK$ molecular state. Recent studies show that the three-body $DDK$ system binds as well with a binding energy about 60$\sim$70 MeV. The $DDK$ bound state has isospin $1/2$ and spin-parity $0^-$. If discovered either experimentally or in lattice QCD, it will not only provide further support on the molecular nature of the $D_{s0}^*(2317)$, but also provide a way to understand other exotic hadrons expected to be of molecular nature. In the present work, we study its two-body strong decay widths via triangle diagrams. We find that the partial decay width into $DD_s\pi$ is at the order of $2\sim3$ MeV, which seems to be within the reach of the current experiments such as BelleII. As a result, we strongly recommend this decay channel of the $DDK$ bound state to be searched for experimentally., Comment: 6 pages, 4 figures

We introduce an atlas adapted to the Toda flow on the manifold of full flags of any non-compact real semisimple Lie algebra, and on its Hessenberg-type submanifolds. In our local coordinates the Toda flow becomes linear. We use these new coordinates to show that the Toda flow on the manifold of full flags is Morse-Smale, which generalizes the main result of \cite{CSS1} to arbitrary non-compact real semisimple Lie algebras. As a byproduct we describe new features of classical constructions in matrix theory., Comment: Changes regarding the different manifolds associated to Hessenberg-type data and modifications in the presentation

In a recent theoretical work, Phys. Lett. B785, 112 (2018), we proposed that a $K^*$ resonance with hidden charm content arises from the $KD\bar D^*$ dynamics, where the $D\bar D^*$ system is treated as a $Z_c(3900)$ or $X(3872)$. With the motivation of determining its further properties, which can be observed in experiments, we now present a calculation of the decay processes of this $K^*$, namely $K^*(4307)$, to two-body channels. Particularly, we consider the decay channels $J/\psi K^*(892)$, $\bar{D}D_s$, $\bar{D}D_s^*$ and $\bar{D}^* D_s^*$. The mechanisms of the decay to these channels involve triangular loops and are a consequence of the internal structure of the state. Thus, the values found for the decay widths of the proposed $K^*(4307)$ are related to its nature and should be valuable for carrying on an experimental study of the $K^*(4307)$. A $K^*$ state with such a mass (in the charmonium region) and quantum numbers is a clear manifestation of an exotic meson, since, having hidden charm (i.e., a $c\bar c$ pair), its mass and quantum numbers can not be explained within a quark-antiquark description., Comment: Published version

In the past decade, due to the experimental observation of many charmonium-like states, there has been a revival of hadron spectroscopy. In particular, the experimental observation of charged charmonium-like, $Z_c$ states, and bottomonium-like, $Z_b$ states, represents a challenge since they can not be accommodated within the naive quark model. These charged states are good candidates of either tetraquark or molecular states and their observation motivated a vigorous theoretical activity. This is a rapidly evolving field with enormous amount of new experimental information. In this work, we review the current experimental progress and investigate various theoretical interpretations of these candidates of the multiquark states. The present review is written from the perspective of the QCD sum rules approach, where we present the main steps of concrete calculations and compare the results with other approaches and with experimental data., Comment: 90 pages, 27 figures; to be published in Journal of Physics G

We study hyperon resonances by solving coupled channel scattering equations. The coupled systems include pseudoscalar- and vector-baryon channels. The parameters of the model are restricted by making a $\chi^2$-fit to the cross section data on processes: $K^- p \to K^- p$, $K^- p \to \bar K^0 n$, $K^- p \to \eta \Lambda$, $K^- p \to \pi^0 \Lambda$, $K^- p \to \pi^0 \Sigma^0$, $K^- p \to \pi^\pm \Sigma^\mp$. Data on the energy level shift and width of the $1s$ state of the kaonic hydrogen, as well as some cross-section ratios near the threshold are also considered in the fit. Two types of fits are found as a result. In both cases, the properties of $\Lambda(1405)$ are well reproduced. In addition to this, a $\Sigma$ state is also found with mass around 1400 MeV. Cross sections, obtained with one of the two fits, are found to stay close to the data at energies away from the thresholds too, and as a result resonances with higher masses have also been studied., Comment: Published version in Physics. Rev. C

We study the $DDK$ system in a coupled channel approach, by including $DD_s\eta$ and $DD_s\pi$, and find that the dynamics involved in the system forms a bound state with isospin $1/2$ and mass $4140$ MeV when one of the $DK$ pair is resonating in isospin 0, forming the $D^*_{s0}(2317)$. The state can be interpreted as a $DD^*_{s0}(2317)$ molecule like state with exotic quantum numbers: doubly charged, doubly charmed, and with single strangeness., Comment: Published version

Inspired by the recent discovery of the pentaquark states $P_c(4450)$ and $P_c(4380)$, which can be viewed as excited nucleon states with hidden charm, we study the three-body interaction of a kaon and a pair of $D\bar{D}^*$ in isospin 0 and 1. We show that the two body interactions stringently constrained by the existence of the $D_{s0}^*(2317)$, $D^*_{s1}(2460)$, $X(3872)$, and $Z_c(3900)$, which are widely believed to contain large $DK$, $D^* K$, and $D\bar{D}^*$ components, inevitably lead to the existence of a heavy $K^*$ meson with hidden charm. Concrete coupled channel three-body calculations yield its mass and width as $(4307\pm 2)- i (9\pm 2)$ MeV with $I(J^P)=1/2(1^-)$. This state, if found experimentally, definitely cannot be accommodated in a $q\bar{q}$ picture, and therefore presents a clear case of an exotic hadron., Comment: updated version

In this talk I present the formalism we have used to analyze Lattice data on two meson systems by means of effective field theories. In particular I present the results obtained from a reanalysis of the lattice data on the $KD^{(*)}$ systems, where the states $D^*_{s0}(2317)$ and $D^*_{s1}(2460)$ are found as bound states of $KD$ and $KD^*$, respectively. We confirm the presence of such states in the lattice data and determine the contribution of the $KD$ channel in the wave function of $D^*_{s0}(2317)$ and that of $KD^*$ in the wave function of $D^*_{s1}(2460)$. Our findings indicate a large meson-meson component in the two cases., Comment: Proceedings Light Cone 2017

In relativistic heavy ion collisions, after the quark gluon plasma (QGP) phase there is a hadron gas (HG) phase. In both phases $J/\psi$ may be formed and destroyed. In this note we study the $J/\psi$ interactions with other mesons in the hadron gas phase. Making use of effective field Lagrangians we obtain the cross sections for the production and absorption processes. With respect to the existing calculations, the improvements introduced here are the inclusion of $K$ and $K^*$'s in the effective Lagrangian approach and the inclusion of processes involving the new exotic charmonium states $Z_c(3900)$ and $Z_c(4025)$. We conclude that the interactions between $J/\psi$ and all the considered mesons reduce the original $J/\psi$ abundance ( determined at the end of the quark gluon plasma phase ) by 20 \% and 24 \% in RHIC and LHC collisions respectively. Consequently, any really significant change in the $J/\psi$ abundance comes from dissociation and regeneration processes in the QGP phase., Comment: 4 pages, 2 figures. Contribution to the Proceedings of the XIV HADRON PHYSICS, 2018, MARCH 18-23, FLORIANOPOLIS, BRAZIL

In this manuscript we discuss the results of our recent study on $\Xi$ resonances. We have studied meson-baryon interaction with strangeness $-2$ by solving scattering equations in a coupled channel approach and found that the dynamics gives rise to the development of two poles in the complex plane close to the real axis. The corresponding narrow states have isospin half and spin half in one case and spin 3/2 in the other case. We find that the properties of the isospin and spin 1/2 state are strikingly similar to $\Xi(1690)$, while the state with spin 3/2 can be related to $\Xi(2120)$. We find that our results on $\Xi(1690)$ are in good agreement with the data available from the BELLE and BABAR Collaborations. Our formalism consists of treating pseudoscalar-baryon and vector-baryon channels on an equal footing. Since the thresholds of such channels are distributed over a relatively larger energy range, we obtain all interaction kernels needed to solve the Bethe-Salpeter equation without resorting to any nonrelativistic approximation even though the amplitudes are calculated at low energies., Comment: Conference proceedings for Hadron 2017 (Salamanca, Spain)

In this talk I present the results obtained using effective field theories in a finite volume from a reanalysis of lattice data on the $KD^{(*)}$ systems, where bound states of $KD$ and $KD^*$ are found and associated with the states $D^*_{s0}(2317)$ and $D^*_{s1}(2460)$, respectively. We confirm the presence of such states on the lattice data and determine the weight of the $KD$ channel in the wave function of $D^*_{s0}(2317)$ and that of $KD^*$ in the wave function of $D^*_{s1}(2460)$. Our results indicate a large meson-meson component in both cases., Comment: Conference Proceedings, Hadron 2017, Salamanca, Spain

In heavy ion collisions after the quark-gluon plasma there is a hadronic gas phase. Using effective Lagrangians we study the interactions of charmed mesons which lead to $J/\psi$ production and absorption in this gas. We update and extend previous calculations introducing strange meson interactions and also including the interactions mediated by the recently measured exotic charmonium resonances $Z(3900)$ and $Z(4025)$. These resonances open new reaction channels for the $J/\psi$, which could potentially lead to changes in its multiplicity. We compute the $J/\psi$ production cross section in processes such as $D_{(s)}^{(*)} + \bar{D}^{(*)} \to J/\psi + (\pi, \rho, K, K^{\ast})$ and also the $J/\psi$ absorption cross section in the corresponding inverse processes. Using the obtained cross sections as input to solve the rate equation, we conclude that the interactions in the hadron gas phase do not significantly affect the $J/\Psi$ abundance. In other words, there is neither a charmonium suppression nor charmonium regeneration from light mesons in the hadronic phase., Comment: Corrections in the text and in the references, 14 pages 6 figures

Let $G$ be a compact connected semisimple Lie group with Lie algebra $\mathfrak{g}$. Let $\mathcal{O}\subset\mathfrak{g}^*$ be a coadjoint orbit. The action of $G$ on $\mathcal{O}$ induces a morphism $\rho:G\to \mathrm{Homeo}(\mathcal{O})$. We prove that the induced map $\pi_1(\rho):\pi_1(G)\to\pi_1(\mathrm{Homeo}(\mathcal{O}))$ is injective. This strengthens a theorem of McDuff and Tolman (conjectured by Weinstein in 1989) according to which the analogous map $G\to\mathrm{Ham}(\mathcal{O})$ is injective on fundamental groups, where $\mathrm{Ham}(\mathcal{O})$ is the group of Hamiltonian diffeomorphisms of the standard symplectic structure on $\mathcal{O}$. To prove our theorem we associate to every nontrivial element of $\pi_1(G)$ a bundle over $S^2$ with fiber $\mathcal{O}$, using the standard patching construction. We then prove that the resulting bundle is topologically nontrivial by studying its cohomology. For this, we prove that it suffices to consider the case in which $G$ is simple and $\mathcal{O}$ is a minimal orbit, and then we prove our result for simple $G$ and minimal orbit $\mathcal{O}$ in a case by case analysis; the proof for the exceptional groups $E_6$ and $E_7$ relies on computer calculations, while all the other ones are addressed by hand. A basic tool in some of our computations is a generalization of Chevalley's formula to bundles of coadjoint orbits over $S^2$ that we prove in this paper.