In 2003 the Belle collaboration announced the discovery of the X(3872) particle. This was confirmed shortly thereafter by the CDF, D0 and BaBar collaborations, and later by the LHCb collaboration. Based on the decay modes that have been observed to date, it is clear that this particle is a hadron, that is, a composite particle that experiences the strong nuclear force. The X(3872) was found within a family of well understood hadrons called charmonia. Interestingly, it is quite difficult to interpret the X(3872) as a charmonium state. For this reason it has been widely speculated that the X(3872) cannot be understood in terms of the quark model, unlike the vast majority of hadrons observed to date. Such hitherto unobserved particles are called exotic hadrons. Since the discovery of the X(3872), many similarly anomalous charmonium-like particles have been discovered. As would be expected, some unanticipated hadrons have also been found in the closely related bottomonium spectrum. These particles are collectively referred to as heavy quarkonium-like. Evidence is growing that at least some of these particles are exotic hadrons. If confirmed, this would have dramatic implications for our understanding of the strong nuclear force. A major experimental and theoretical effort is now underway in the field of hadron spectroscopy to determine the identities of the heavy quarkonium-like states. In order to investigate the possibility that some of these states could be exotic hadrons, theoretical calculations are needed to firmly establish their properties. One of the main arguments for the existence of exotic hadrons is that they are predicted by the fundamental theory of the strong interaction, Quantum Chromodynamics (QCD). Therefore it is desirable to predict the properties of exotic hadrons using a theoretical approach that is firmly based in QCD. One such method is QCD sum rules (QSR). The research presented here uses the QSR technique to study exotic hadrons. There are several themes in this work. First is the use of QSR to predict the masses of exotic hadrons that may exist among the heavy quarkonium-like states. The second theme is the application of sophisticated loop integration methods in order to obtain more complete theoretical results. These in turn can be extended to higher orders in the perturbative expansion in order to predict the properties of exotic hadrons more accurately. The third theme involves developing a renormalization methodology for these higher order calculations. This research has implications for the Y(3940), X(3872), Zc(3895), Yb(10890), Zb(10610) and Zb(10650) particles, thereby contributing to the ongoing effort to understand these and other heavy quarkonium-like states.

Neste trabalho usamos as regras de soma da QCD para calcular as massas e constantes de acoplamento ou decaimento dos estados exóticos theta+(1540) e cascata--(1862) (pentaquarks), dos mesons escalares charmosos DsJ+(2317), D0(2308) e D0(2405) e do meson axial X(3872). Os mesons foram também tratados como estados exóticos de quatro quarks (tetraquarks). Dois métodos de regra de soma foram aplicados e uma atenção especial foi dada aos limites de validade e incertezas da regra de soma. Em todos os casos encontramos resultados compatíveis com os dados experimentais existentes, mas no caso dos pentaquarks e dos mesons escalares as regras de soma têm algumas de suas condições violadas, levantando a questão sobre a existência das ressonâncias na forma em que foram propostas. Fizemos também uma previsão para um méson axial Xb, que é uma expansão para o setor botônico do modelo assumido para o X(3872). / In this work the QCD Sum Rules have been used to obtain masses and coupling or decay constants of the theta+(1540) and cascade--(1862) pentaquarks, the DsJ+(2317), D0(2308) and D0(2405) charmed scalar mesons and the X(3872) axial meson. The mesons have been treated as 4-quark exotic states (tetraquarks). Two sum rules methods have been used with special attention given to the limits and uncertainties of the sum rules. Results consistent with experimental data have been found in all cases, but some of the sum rules constraints have been violated in the calculation of the pentaquarks and scalar mesons, leaving questions about the existence of the states as they have been built here. A prediction was also made for the mass of a state expanding the model used for X(3872) to the botton sector, named Xb.

Neste trabalho usamos as regras de soma da QCD para calcular as massas e constantes de acoplamento ou decaimento dos estados exóticos theta+(1540) e cascata--(1862) (pentaquarks), dos mesons escalares charmosos DsJ+(2317), D0(2308) e D0(2405) e do meson axial X(3872). Os mesons foram também tratados como estados exóticos de quatro quarks (tetraquarks). Dois métodos de regra de soma foram aplicados e uma atenção especial foi dada aos limites de validade e incertezas da regra de soma. Em todos os casos encontramos resultados compatíveis com os dados experimentais existentes, mas no caso dos pentaquarks e dos mesons escalares as regras de soma têm algumas de suas condições violadas, levantando a questão sobre a existência das ressonâncias na forma em que foram propostas. Fizemos também uma previsão para um méson axial Xb, que é uma expansão para o setor botônico do modelo assumido para o X(3872). / In this work the QCD Sum Rules have been used to obtain masses and coupling or decay constants of the theta+(1540) and cascade--(1862) pentaquarks, the DsJ+(2317), D0(2308) and D0(2405) charmed scalar mesons and the X(3872) axial meson. The mesons have been treated as 4-quark exotic states (tetraquarks). Two sum rules methods have been used with special attention given to the limits and uncertainties of the sum rules. Results consistent with experimental data have been found in all cases, but some of the sum rules constraints have been violated in the calculation of the pentaquarks and scalar mesons, leaving questions about the existence of the states as they have been built here. A prediction was also made for the mass of a state expanding the model used for X(3872) to the botton sector, named Xb.

Usamos as regras de soma da QCD para obter a massa dos pentaquarks \" \'teta\' POT.+\"(1540) e \"\'ksi\' POT.--\" (1862), a largura de decaimento da \"\'teta\' POT.+\" e a constante de acoplamento e fator de forma presentes no vertice J/ \'psi\' \"DD POT.*\". No estudo dos pentaquarks, usamos dois tipos de campos interpolantes contendo dois diquarks altamente correlacionados. Obtemos as massas consistentes com os dados experimentais, porém esta regra de soma têm uma grande contribuição do contínuo e a OPE não é muito boa. Obtivemos uma largura de decaimento compatível com os valores experimentais desde que sejam subtraídos diagramas que representam a \" \'teta\' POT.+\" como um estado ligado K - n. No estudo do vértice vertice J/ \'psi\' \"DD POT.*\" calculamos o fator de forma e a constante de acoplamento, considerando três casos: D off-shell, \"D POT.*\" off-shell e J/ \'psi\' off-shell. A constante de acoplamento é a mesma nesses três casos, porém o fator de forma depende da escolha da partícula off-shell, onde para a J/ \'psi\' off-shell o fator de forma é bem mais duro que o fator de forma obtido para os outros casos. Também comparamos os nossos resultados com outros métodos: o modelo de quark méson constituintes e o modelo de quarks relativísticos constituintes / We use the QCD sum rules to obtain the masses of the pentaquarks _+(1540) and _−−(1862), _+ decay width and the coupling constant and the form factor for the J/ DD* vertex.In the study of the pentaquarks, we use two kinds of interpolating fields, containing two highly correlated diquarks. We get the masses in a good agreement with the experimental value, but this sum rule has a large continuuum contribution and the OPE convergence is not so good. We get the decay width compatible with the experimental value, since we subtract the diagrams that represent _+ as a K − n bound state. In the study of J/ DD* vertex, we calculate the form factor and the coupling constant considering three cases: D off-shell, D* off-shell and J/ off-shell. The coupling constant is the same in those three cases, however the form factor depends on the choice of the particle off-shell, where for the J/ off-shell the form factor is much harder than the form factor obtained for the other cases. We also compare our results with other methods: the constituent quark meson model and the relativistic constituent quark model.

Usamos as regras de soma da QCD para obter a massa dos pentaquarks \" \'teta\' POT.+\"(1540) e \"\'ksi\' POT.--\" (1862), a largura de decaimento da \"\'teta\' POT.+\" e a constante de acoplamento e fator de forma presentes no vertice J/ \'psi\' \"DD POT.*\". No estudo dos pentaquarks, usamos dois tipos de campos interpolantes contendo dois diquarks altamente correlacionados. Obtemos as massas consistentes com os dados experimentais, porém esta regra de soma têm uma grande contribuição do contínuo e a OPE não é muito boa. Obtivemos uma largura de decaimento compatível com os valores experimentais desde que sejam subtraídos diagramas que representam a \" \'teta\' POT.+\" como um estado ligado K - n. No estudo do vértice vertice J/ \'psi\' \"DD POT.*\" calculamos o fator de forma e a constante de acoplamento, considerando três casos: D off-shell, \"D POT.*\" off-shell e J/ \'psi\' off-shell. A constante de acoplamento é a mesma nesses três casos, porém o fator de forma depende da escolha da partícula off-shell, onde para a J/ \'psi\' off-shell o fator de forma é bem mais duro que o fator de forma obtido para os outros casos. Também comparamos os nossos resultados com outros métodos: o modelo de quark méson constituintes e o modelo de quarks relativísticos constituintes / We use the QCD sum rules to obtain the masses of the pentaquarks _+(1540) and _−−(1862), _+ decay width and the coupling constant and the form factor for the J/ DD* vertex.In the study of the pentaquarks, we use two kinds of interpolating fields, containing two highly correlated diquarks. We get the masses in a good agreement with the experimental value, but this sum rule has a large continuuum contribution and the OPE convergence is not so good. We get the decay width compatible with the experimental value, since we subtract the diagrams that represent _+ as a K − n bound state. In the study of J/ DD* vertex, we calculate the form factor and the coupling constant considering three cases: D off-shell, D* off-shell and J/ off-shell. The coupling constant is the same in those three cases, however the form factor depends on the choice of the particle off-shell, where for the J/ off-shell the form factor is much harder than the form factor obtained for the other cases. We also compare our results with other methods: the constituent quark meson model and the relativistic constituent quark model.

Unexpected properties of recently discovered mesons DsJ(2317) and DsJ(2460) have caused an excitement in the high energy community. These mesons are under experimental study in BaBar, Belle and CLEO. The experimental data on these mesons is quite limited at the moment, but it is expected to be improved in the following years. The unexpected properties of these mesons, such as the low mass, and small width, have caused speculations about their structure. Various models have been proposed which go beyond the simple quark-antiquark picture of the mesons, such as a meson molecule, or a four-quark state. Therefore, understanding the underlying structure of these mesons can reveal a deeper understanding of QCD. In this thesis, the strong decay of the DsJ(2317) meson, DsJ(2317)--&gt / Dspi0, is studied using three-point QCD Sum Rules method in the conventional cs framework. DsJ(2317) -&gt / Dspi0 decay violates isospin symmetry. Therefore, this decay is studied as a two stage process / an isospin conserving DsJ(2317) --&gt / Ds eta decay followed by the conversion of eta into a pi0 due to isospin violation.

The recently discovered DsJ(2317) and DsJ(2460) mesons had stimulated many theoretical and experimental studies due to their unexpected properties. In this thesis, we make a review of the predictions on the properties of these mesons using the quark model and QCD Sum Rules. We studied different models about the structure of these mesons, which are suggested because of their unexpected properties. Moreover, using the quark model which implies that the structure of DsJ meson as cs and QCD Sum Rules method, we investigated the semileptonic decay DsJ(2317)--&gt / D0 l nu.

Quantum Chromodynamics(QCD) is part of the Standard Model(SM) that describes the interaction of fundamental particles. In QCD, due to the fact that strong coupling constant is large at low energies, perturbative approaches do not work. For this reason, non-perturbative approaches have to be used for studying the properties of hadrons. Among several non-perturbative approaches, QCD sum rules is one of the reliable methods which is applied to understand the properties of hadrons and their interactions. In this thesis, the semileptonic rare decays of $B$ meson to $K_{1}(1270)$ and $K_{1} (1400)$ are analyzed in the framework of three point QCD sum rules approach. The $Brightarrow K_{1} (1270,1400) ell^+ ell^-$ decays are significant flavor changing neutral current (FCNC) decays of the $B$ meson, since FCNC processes are forbidden at tree level at SM. These decays are sensitive to the new physics beyond SM. The radiative $Brightarrow K_{1}(1270) gamma$ decay is observed experimentally. Although semileptonic $Bto K_1(1270,1400)$ decays are still not observed, they are expected to be observed at future B factories. These decays happens at the quark level with $brightarrow s ell^+ ell^- $ transition, providing new opportunities for calculating CKM matrix elements: $V_{tb}$ and $V_{ts}$. Applying three point QCD sum rules to $Brightarrow K_{1} (1270,1400) ell^+ ell^-$ decays is tricky, due to the fact that the $K_{1} (1270)$ and $K_{1} (1400)$ states are the mixtures of ideal $^{3}P_{1}(K_{1}^{A})$ and $^{1}P_{1}(K_{1}^{B})$ orbital angular momentum states. First, by taking axial vector and tensor current definitions for $K_1$ mesons, the transition form factors of $Brightarrow K_{1A} ell^+ ell^-$ and $Brightarrow K_{1B} ell^+ ell^-$ are calculated. Then using the definitions for $K_1$ mixing, the transition form factors of $Brightarrow K_{1} (1270,1400) ell^+ ell^-$ decays are obtained. The results of these form factors are used to estimate the branching ratio of $B$ meson into $K_1(1270)$ and $K_1(1400)$. The results obtained for form factors and branching fractions are also compared with the ones in the literature.

Nesta tese, discutimos em detalhes a técnica das Regras de Soma da QCD (RSQCD) e suas aplicações em sistemas hadrônicos situados na região de massa do charmônio. Em particular, calculamos a massa, as constantes de decaimento e acoplamento, bem como a largura de decaimento dos estados $Y(4260)$,$Y(3940)$ e $Z_c^+(3900)$. Além disso, consideramos a existência do parceiro estranho deste último, o $Z^+_{cs}(3970)$, e calculamos sua largura de decaimento de modo a prever seu valor em futuros experimentos. Usamos modelos ditos exóticos para descrever tais estados. Para o $Y(4260)$ e o $Y(3940)$ usamos correntes de mistura charmônio - tetraquarks. Para os estados carregados usamos uma corrente de tetraquarks. Como resultado das aplicações das RSQCD nesses sistemas, obtivemos valores de massa e largura compatíveis com os valores experimentais medidos pelas colaborações BESIII, Belle, Babar e CLEO-c. Dessa forma, podemos afirmar que os modelos utilizados fornecem uma boa interpretação para esses estados. Investigamos também, aplicando técnicas de teorias efetivas, os estados carregados $Z^+_c(4025)$ e novamente o $Z_c^+(3900)$, além dos estados no setor do bottom $Z^+_b(10610)$ e $Z_b^+(10650)$. Usamos as Lagrangianas da Simetria Oculta de Calibre Local (HGS) e também as regras da Simetria de Spin do Quark Pesado (HQSS) para determinarmos as interações $D\\bar{D}^*$, $D^*\\bar{D}^*$, $B\\bar{B}^*$ e $B^*\\bar{B}^*$ via troca de mésons vetoriais pesados e devido à troca de dois píons correlacionados e não correlacionados entre si. Determinamos o potencial para cada interação e, com isso, procuramos por pólos na solução da matriz $T$ na equação de Bethe-Salpeter, cujo kernel é dado pelo potencial. Como resultado desses estudos, obtivemos para as interações no setor do charme, estados ligados cuja massa e largura estão em razoável acordo com os estados carregados $Z^+_c(4025)$ e $Z_c^+(3900)$. Para as interações no setor do bottom, obtemos um estado fracamente ligado próximo do limiar de massa $B\\bar{B}^*$ cuja largura e massa são compatíveis com a estrutura $Z_b^+(10610)$ observada pela Colaboração Belle. Obtivemos um cusp no limiar de massa $B^*\\bar{B}^*$ próximo do valor da estrutura $Z_b^ (10650)$ / In this thesis, we discuss in details the QCD Sum Rules (QCDSR) technique and its application to the study of hadronic systems situated in the charmonium mass region. In particular, we applied QCDSR to calculate hadronic properties such as the mass, the coupling contants as well as the total decay width of the $Y(4260)$, $Y(3940)$ and $Z_c^+(3900)$ charmoniumlike states. We have also predicted the decay width of the strange partner of the $Z_c^+(3900)$, called $Z_{cs}^+(3970)$, to be searched in future experiments. In order to describe these states, we used exotic models. For $Y(4260)$ and $Y(3940)$ states we used mixed charmonium-tetraquarks interpolating currents. For the charged states we used tetraquark currents. As a result of the application of QCDSR to these systems, we obtained masses and decay widths in good agreement with the experimental values measured by BESIII, Babar, and CLEO-c collaborations. Therefore, the currents we used within QCDSR approach provide a good interpretation for these states. Furthermore, applying effective field theories techniques, we also investigated the charged states $Z_c^+(4025)$ and $Z_c^+(3900)$, in addition to $Z^+_b(10610)$ and $Z_b^+(10650)$ in the bottom sector. Specifically, we used hidden local symmetry Lagrangians (HGS) together with heavy quark spin symmetry rules (HQSS) in order to study the interactions $D\\bar{D}^*$, $D^*\\bar{D}^*$, $B\\bar{B}^*$ and $B^*\\bar{B}^*$ by means of the heavy vector exchange and also from the exchange of two pions, interacting and noninteracting among themselves. We obtained the potencial for each interaction, then we used them as a kernel of the Bethe-Salpeter equation in order to look for poles in the $T$-matrix. Our aim was to relate these poles with the charmoniumlike states of interest. As a result, in the charm sector, we obtained bound states whoses masses and widths are in a good agreement with the charged states we have studied. With respect to the bottom sector, we have found a loosely bound state very close to the $B\\bar{B}^*$ threshold with mass and width compatible with the structure $Z_b(10610)$ observed by Belle colaboration. We have obtained a cusp in the $B^*\\bar{B}^*$ threshold very close to the mass of the $Z_b^+(10650)$ state.

For the anti-charmed pentaquark state with and without strangeness a QCD sum rule analysis, which is one of the nonperturbative approaches, is presented. For this purpose we employ pentaquark currents with and without strangeness, with two different current for each case. To refine the sum rules we also consider the DN continuum contribution in our analysis since this procedure is important to identify the signal of the pentaquark state. While the sum rules for most of the currents are either non-convergent or dominated by the DN continuum, the one for the non-strange pentaquark current composed of two diquarks and an antiquark, is convergent and has a structure consistent with a positive parity pentaquark state after subtracting out the DN continuum contribution. Arguments are presented on the similarity between the result of the present analysis and that based on the constituent quark models, which predict more stable pentaquark states when the antiquark is heavy.