Please use this identifier to cite or link to this item:
Title: Effective-theory description of heavy-flavored hadrons and their properties in a hot medium
Author: Montaña Faiget, Glòria
Director/Tutor: Ramos Gómez, Àngels
Tolós Rigueiro, Laura
Keywords: Interaccions d'hadrons
Teoria de camps (Física)
Hadron interactions
Field theory (Physics)
Issue Date: 8-Jul-2022
Publisher: Universitat de Barcelona
Abstract: [eng] For many decades after the conception of the quark model in 1964, and the development of quantum chromodynamics (QCD) a few years later as the theory governing the strong interaction between quarks and gluons, there was no experimental evidence of the existence of hadronic states beyond the quark-antiquark mesons and the three-quark baryons. In the last two decades, however, with the explosion of data in electron–positron and hadron colliders, many states have been observed that do not fit in this picture, especially in the heavy-flavor sector. Evidence of the existence of the so-called exotic hadrons has recently prompted a lot of activity in the field of hadron physics, with experimental programs in ongoing and upcoming facilities dedicated to the search for new exotic mesons and baryons, and many theoretical efforts trying to disentangle, for instance, compact multiquark structures from hadronic molecules. In this dissertation, we focus on recently seen exotic hadrons with heavy-quark content that may be understood as being generated dynamically from the hadron–hadron interaction. This interaction is derived from a suitable effective Lagrangian and properly unitarized in a full coupled-channel basis. In particular, we discuss the possible interpretation of some of the Ωc* excited states recently discovered at LHCb as being meson–baryon molecular states. We also discuss the dynamical generation of excited open-charm mesons from the scattering of pseudoscalar and vector charmed mesons off light mesons. We show that a double-pole structure is predicted for the D0*(2300) state, as well as for the D1(2430), within the molecular picture, while the Ds0*(2317) and the Ds1(2460) may be interpreted as molecular bound states. Extensions of these calculations to the bottom sector are also presented. Moreover, charmed hadrons are a promising probe of the quark-gluon plasma (QGP) phase that is expected to be created in heavy-ion collision experimental facilities. Charm and anticharm quarks are produced in the early stages of the collision and experience the whole evolution of the QGP, before hadronizing predominantly into open-charm mesons. To describe the experimental data, it is necessary to understand, from the theoretical side, the propagation of the D mesons in the hadronic phase and their interaction with the surrounding medium of light mesons. The approach that we employ in this thesis to study the thermal modification of open heavy-flavor mesons in a hot medium is based on the use of effective theories. By means of an extension to finite temperature of the unitarized effective interactions with the light mesons, we obtain the in-medium spectral properties of the D, D*, Ds, and Ds* ground-state mesons. We also analyze the temperature dependence of the masses and the decay widths of the dynamically generated states. Additionally, we provide results for the bottomed mesons by exploiting the heavy-quark flavor symmetry of the Lagrangian. In order to test the results of the thermal effective theory against lattice QCD calculations, we further employ the temperature-dependent scattering amplitudes and spectral functions to compute charm Euclidean correlators. The spectral properties of charmed mesons at finite temperature can be extracted from lattice QCD data of meson Euclidean correlators, yet relying on a priori assumptions about the shape of the spectral function. Hence, we compare both approaches at the level of Euclidean correlators and find that they compare reasonably well at temperatures below the QCD phase transition temperature. We also present calculations of off-shell transport coefficients in the hadronic phase, such as the drag force and the diffusion coefficients. Contrary to previous approaches in the literature, we implement in-medium scattering amplitudes and the thermal dependence of the heavy-meson spectral properties. The transport coefficients in the QGP phase have been recently computed with lattice QCD and extracted from Bayesian analyses of heavy-ion collision data. We observe a smooth matching with our results at the QCD phase transition temperature
[cat] La física hadrònica tal com l’entenem en l’actualitat es remunta a la concepció del model de quarks l’any 1964 i la formalització de la teoria de la cromodinàmica quàntica (QCD) uns anys més tard. Durant dècades no es va trobar evidència de l’existència d’hadrons amb una composició diferent de la dels mesons (quark-antiquark) i barions (tres quarks) ordinaris. Tanmateix, les regles de la QCD permeten altres combinacions més exòtiques. En el darrers vint anys, amb l’explosió de dades en experiments de col·lisions electró–positró i d’hadrons, s’han descobert diversos candidats a hadrons exòtics. En aquesta tesi doctoral s’estudien hadrons exòtics amb contingut pesant que han estat observats recentment: els estats excitats Ωc* i Ωb* en el sector bariònic, i els estats D0*(2300), D1(2430), Ds0*(2317) i Ds1(2460) en el sector mesònic, i que es poden descriure com estats hadrònics moleculars generats dinàmicament per la interacció hadró–hadró. Aquest interacció deriva d’un Lagrangià efectiu adequat i s’unitaritza en canals acoblats. D’altra banda, a altes energies té lloc una transició de fase de matèria hadrònica a una fase desconfinada coneguda amb el nom de plasma de quarks i gluons (QGP) i que només es pot trobar a temperatures i/o densitats bariòniques extremadament altes. Experimentalment, les condicions d’alta temperatura i baixa densitat bariònica necessàries per crear un QGP calent es poden aconseguir amb col·lisions d’ions pesants a altes energies. Els hadrons pesants permeten sondejar la formació de la fase de QGP. El treball presentat en aquesta memòria s’orienta a millorar la comprensió de la modificació de les propietats dels mesons amb sabor pesant en un medi calent mitjançant l’ús de teories efectives. A partir de l’extensió a temperatura finita de la interaccions efectives unitaritzades, s’obtenen les propietats en el medi dels mesons amb sabor pesant, tant dels de l’estat fonamental com dels estats generats dinàmicament. Els resultats de les amplituds de dispersió i de les funcions espectrals s’utilitzen per calcular correladors Euclidians i coeficients de transport en la fase hadrònica. Es troba un bon acord amb computacions de lattice QCD, així com amb coeficients de transport obtinguts a partir d’anàlisis Bayesians de dades de col·lisions d’ions pesants a la temperatura de transició de fase.
Appears in Collections:Tesis Doctorals - Departament - Física Quàntica i Astrofísica

Files in This Item:
File Description SizeFormat 
GMF_PhD_THESIS.pdf13.51 MBAdobe PDFView/Open

This item is licensed under a Creative Commons License Creative Commons