arXiv subjects

A. Martinez Torres

Publications and source records attributed to A. Martinez Torres.

At least 37 records · Page 2Linked to original sources

arXiv2022

Exotic heavy hadrons with a three-body nature

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 $Δ^*$ 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.

hep-ph↗

arXiv2021

Photoproduction of $Λ^$ and $Σ^$ resonances with $J^P=1/2^-$ off the proton

We study the photoproduction of the $Λ(1405)$ and $Σ(1400)$ 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 $KΛ(1405)$ and $KΣ(1400)$ 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 $Λ(1405)$, while for $Σ(1400)$ 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 $Λ(1405)$ and $Σ(1400)$.

hep-ph↗

arXiv2020

Partial decay widths of $ϕ(2170)$ to kaonic resonances

In this work we study the strong decays of $ϕ(2170)$ 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 $ϕ(2170)$ 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 $ϕ(2170)$. Within our formalism, we can also explain the suppressed decay of $ϕ(2170)$ 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.

hep-ph↗

arXiv2020

Decay properties of $N^*(1895)$

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 $Λ(1405)$ and $Σ(1400)$, where the latter is not yet observed experimentally. Such decay processes can be useful to study the properties of the aforementioned hyperon resonances.

hep-ph↗

arXiv2020

Few-body systems consisting of mesons

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.

nucl-th↗

arXiv2020

Hyperon resonances and meson-baryon interactions in isospin 1

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.

hep-ph↗

arXiv2019

Heavy $K^*(4307)$ meson with hidden charm

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 $M-iΓ/2=4307\pm2-i9\pm2$ 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.

hep-ph↗

arXiv2019

Production of the (predicted) $K^*(4307)$ in $B$ decays

In this work we study the production of $K^*(4307)$ in $B$ decays by determining the $J/ψπ^{+(0)}K^{0}$ and $J/ψπ^- K^+$ invariant mass distributions of the processes $B^+\to J/ψπ^+π^0 K^0$ and $B^+\to J/ψπ^+π^- K^+$, 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 $J/ψπK$ 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).

hep-ph↗

arXiv2019

Multiple charm and hidden charm mesons with strangeness

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.

hep-ph↗

arXiv2019

On the two-body decay processes of the predicted three-body $K^*(4307)$ resonance

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 $J/ψK^*(892)$, $\bar{D}D_s$, $\bar{D}D_s^*$ 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.

hep-ph↗

arXiv2019

QCD Sum Rules Approach to the $X,~Y$ and $Z$ States

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.

hep-ph↗

arXiv2019

Bound state formation in the $DDK$ system

We study the $DDK$ system in a coupled channel approach, by including $DD_sη$ and $DD_sπ$, 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.

hep-ph↗

arXiv2018

$K^*$ mesons with hidden charm arising from $KX(3872)$ and $KZ_c(3900)$ dynamics

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.

hep-ph↗

arXiv2018

Effective Field Theories in a Finite Volume

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.

hep-lat↗

arXiv2017

An analysis of the Lattice QCD spectra for $D^_{s0}(2317)$ and $D^_{s1}(2460)$

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.

hep-lat↗

arXiv2017

On the absorption and production cross sections of $K$ and $K^*$

We have computed the isospin and spin averaged cross sections of the processes $πK^*\to ρK$ and $ρK^*\to πK$, which are crucial in the determination of the abundances of $K^*$ and $K$ in heavy ion collisions. Improving previous calculations, we have considered several mechanisms which were missing, such as the exchange of axial and vector resonances ($K_1(1270)$, $K^*_2(1430)$, $h_1(1170)$, etc...) and also other processes such as $πK^*\to ωK, ϕK$ and $ωK^*,\,ϕK^*\to πK$. We find that some of these mechanisms give important contributions to the cross section. Our results also suggest that, in a hadron gas, $K^*$ production might be more important than its absorption.

hep-ph↗

arXiv2016

X, Y and Z States

Many new states in the charmonium mass region were recently discovered by BaBar, Belle, CLEO-c, CDF, D0, BESIII, LHCb and CMS Collaborations. We use the QCD Sum Rule approach to study the possible structure of some of these states.

hep-ph↗

arXiv2016

$X(3872)$ production and absorption in a hot hadron gas

We calculate the time evolution of the $X(3872)$ abundance in the hot hadron gas produced in the late stage of heavy ion collisions. We use effective field Lagrangians to obtain the production and dissociation cross sections of $X(3872)$. In this evaluation we include diagrams involving the anomalous couplings $πD^*\bar{D}^*$ and $X \bar{D}^{\ast} D^{\ast}$ and also the couplings of the $X(3872)$ with charged $D$ and $D^*$ mesons. With these new terms the $X(3872)$ interaction cross sections are much larger than those found in previous works. Using these cross sections as input in rate equations, we conclude that during the expansion and cooling of the hadronic gas, the number of $X(3872)$, originally produced at the end of the mixed QGP/hadron gas phase, is reduced by a factor of 4.

hep-ph↗