The sensitivity of the charmonium and bottomonium spectroscopy to the short distance part of the interquark potential is critically re-examined using the latest data. We confirm that the data cannot accommodate a QCD scale parameter (Ʌ(_MS)) smaller than about 150 MeV, whereas we find no constraint on larger values of the scale parameter, contrary to a previous analysis. The effects of dynamical heavy quark masses in the loop correction to the perturbative potential is studied in detail and the effective four quark theory with a massive charmed quark is found to give an accurate description of the perturbative potential for quarkonia of mass up to about 250 GeV. Predictions for the heavy quarkonium system of toponium are found to be very sensitive to the behaviour of the short-distance region of the potential and it is argued that the experimental determination of the mass and e(^+)(^-) decay width of the 1S and 2S toponium resonances (of mass around 80 GeV) with accuracy anticipated at the forthcoming e(^+)e(^-) colliders should enable the QCD scale parameter to be determined to within ± 100 MeV. The hadronic decays of the lowest S- and P-wave states of charmonium and bottomonium are examined in the light of recent experimental determination. All but the individual P-wave decays in charmonium can be adequately accounted for using reasonable values of the strong coupling constant and we are led to believe that the discrepancy lies with wavefunction corrections.

Zugl.: Regensburg, Univ., Diss., 2010

Recentemente, a colaboração CDF encontrou evidência para uma nova ressonância do tipo do charmônio no espectro de massa invariante do decaimento $B^{\\pm} ightarrow K^{\\pm} J/\\psi \\phi$. Esta ressonância tem uma massa de $4274.4^{+8.4}_{-6.7} \\, \\mathrm(estat) \\, \\pm 1.9 (sist) \\, \\mathrm$ - recebendo, portanto, o nome de Y(4274) - e largura total de decaimento de $32.3^{+21.9}_{-15.3} \\, \\mathrm(estat) \\, \\pm 7.6 (sist) \\, \\mathrm$. A significância estatística para esta estrutura é cerca de 3.1 $\\sigma$. Usando as regras de soma da QCD e um modelo molecular similar a um modelo proposto anteriormente para explicar a estrutura das ressonâncias Y(3930) e Y(4140), estudamos o Y(4274) como a molécula hadrônica $D_ \\bar_s + h.c.$ com $J^=0^{-+}$, e seu possível parceiro molecular, a molécula $D_ \\bar + h.c.$. Obtivemos que $m_{D_ \\bar_} = (4.78 \\pm 0.54) \\, \\mathrm$, um resultado compatível, dentro da estimativa do erro, com a massa do Y(4274). Para seu parceiro molecular, temos que $m_{D_ \\bar} = (4.55 \\pm 0.49) \\, \\mathrm$. Os estados moleculares análogos do tipo do botomônio, $B_ \\bar_s + h.c.$ e $B_ \\bar+h.c.$, também foram estudados. / Recently, the CDF collaboration found evidence for a new charmonium-like resonance on the $B^{\\pm} ightarrow K^{\\pm} J/\\psi \\phi$ invariant mass spectrum. This resonance has a mass of $4274.4^{+8.4}_{-6.7} \\, \\mathrm(stat) \\, \\pm 1.9 (syst) \\, \\mathrm{MeV}$ - thus being named the Y(4274) resonance - and total decay width of $32.3^{+21.9}_{-15.3} \\, \\mathrm(stat) \\, \\pm 7.6 (syst) \\, \\mathrm{MeV}$. The statistical significance of this structure is approximately 3.1 $\\sigma$. Using the QCD sum rules and a molecular model similar to a model previously proposed to explain the strutcture of the Y(3930) and Y(4140) resonances, we studied the Y(4274) as the hadronic molecule $D_{s0} \\bar{D}_s + h.c.$ with $J^{PC}=0^{-+}$ and its molecular partner, the molecule $D_{0} \\bar{D} + h.c.$. We obtained that $m_{D_{s0} \\bar{D}_{s}} = (4.78 \\pm 0.54) \\, \\mathrm{GeV}$, a result that is compatible, within the error estimates, with the mass of Y(4274). For its molecular partner, we have that $m_{D_{0} \\bar{D}} = (4.55 \\pm 0.49) \\, \\mathrm{GeV}$. The analogous bottomonium-like molecular states, $B_{s0} \\bar{B}_s + h.c.$ e $B_{0} \\bar{B}+h.c.$, were also studied.

Heidelberg, Univ., Diplomarb., 2002.

Recentemente, a colaboração CDF encontrou evidência para uma nova ressonância do tipo do charmônio no espectro de massa invariante do decaimento $B^{\\pm} ightarrow K^{\\pm} J/\\psi \\phi$. Esta ressonância tem uma massa de $4274.4^{+8.4}_{-6.7} \\, \\mathrm(estat) \\, \\pm 1.9 (sist) \\, \\mathrm$ - recebendo, portanto, o nome de Y(4274) - e largura total de decaimento de $32.3^{+21.9}_{-15.3} \\, \\mathrm(estat) \\, \\pm 7.6 (sist) \\, \\mathrm$. A significância estatística para esta estrutura é cerca de 3.1 $\\sigma$. Usando as regras de soma da QCD e um modelo molecular similar a um modelo proposto anteriormente para explicar a estrutura das ressonâncias Y(3930) e Y(4140), estudamos o Y(4274) como a molécula hadrônica $D_ \\bar_s + h.c.$ com $J^=0^{-+}$, e seu possível parceiro molecular, a molécula $D_ \\bar + h.c.$. Obtivemos que $m_{D_ \\bar_} = (4.78 \\pm 0.54) \\, \\mathrm$, um resultado compatível, dentro da estimativa do erro, com a massa do Y(4274). Para seu parceiro molecular, temos que $m_{D_ \\bar} = (4.55 \\pm 0.49) \\, \\mathrm$. Os estados moleculares análogos do tipo do botomônio, $B_ \\bar_s + h.c.$ e $B_ \\bar+h.c.$, também foram estudados. / Recently, the CDF collaboration found evidence for a new charmonium-like resonance on the $B^{\\pm} ightarrow K^{\\pm} J/\\psi \\phi$ invariant mass spectrum. This resonance has a mass of $4274.4^{+8.4}_{-6.7} \\, \\mathrm(stat) \\, \\pm 1.9 (syst) \\, \\mathrm{MeV}$ - thus being named the Y(4274) resonance - and total decay width of $32.3^{+21.9}_{-15.3} \\, \\mathrm(stat) \\, \\pm 7.6 (syst) \\, \\mathrm{MeV}$. The statistical significance of this structure is approximately 3.1 $\\sigma$. Using the QCD sum rules and a molecular model similar to a model previously proposed to explain the strutcture of the Y(3930) and Y(4140) resonances, we studied the Y(4274) as the hadronic molecule $D_{s0} \\bar{D}_s + h.c.$ with $J^{PC}=0^{-+}$ and its molecular partner, the molecule $D_{0} \\bar{D} + h.c.$. We obtained that $m_{D_{s0} \\bar{D}_{s}} = (4.78 \\pm 0.54) \\, \\mathrm{GeV}$, a result that is compatible, within the error estimates, with the mass of Y(4274). For its molecular partner, we have that $m_{D_{0} \\bar{D}} = (4.55 \\pm 0.49) \\, \\mathrm{GeV}$. The analogous bottomonium-like molecular states, $B_{s0} \\bar{B}_s + h.c.$ e $B_{0} \\bar{B}+h.c.$, were also studied.

A gauged SU(4) flavor symmetric hadronic Lagrangian with empirical hadron masses is constructed to study charmonium absorption and charmed hadron production in hadronic reactions. For the coupling constants, empirical values are used if available. Otherwise, they are determined from known coupling constants using the SU(4) relations. To take into account the finite sizes of hadrons, form factors are introduced at strong interaction vertices with empirical cutoff parameters. For J/ψabsorption by nucleons, we have included both two-and three-body final states and find that with a cutoff parameter of 1 GeV at interaction vertices involving charm hadrons, the cross section is at most 5 mb and is consistent with that extracted from J/ψproduction from both photo-and proton-nucleus reactions. We have also evaluated the cross sections for charmed hadron production from pion and rho meson interactions with nucleons. With the same cutoff parameter of 1 GeV at interaction vertices, we find that these cross sections have values of a few tenths of mb and are dominated bythe s-channel nucleon pole diagram. For charmed hadron production from proton-proton reactions, their cross sections including bothtwo-andthree-body final states are about 1 batcenter-of-mass energyof 11.5 GeV, which is comparable to the measured inclusive cross section in these reactions.Including photon as a U(1) gauge particle, we have extended the model to study charmed hadron production in photon-proton reactions with both two-and three-body final states included. For form factors, an overall one is introduced in each processin order to maintain the gauge invariance of the total amplitude. Fitting the cutoff parameter in the form factor to the measured total cross section for charmed hadron production in photon-proton reactions at a center-of-mass energy of 6 GeV, the ratio of the cross sections for two-body and three-body final states is consistent with available experimental data.This result is further compared with predictions from the leading-order perturbative QCD calculation. Knowledge of the cross sections for charmonium absorption byhadrons and for charmed hadron production in hadronic reactions is essential for understanding charm production in heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC), where a quark-gluon plasma is expected to be formed during the initial hot dense stage.

Un des buts de l'expérience R704 est l'étude des états $\chi_1$ et $\chi_2$ du charmonium $(c\bar{c)}$ dans leur annihilation J/$\psi$ + photon. Ces états sont formés par interaction d'un jet moléculaire d'hydrogène sur un faisceau refroidi d'antiprotons. L'importance du bruit de fond hadronique conduit à ne s'intéresser qu'aux états finaux électromagnétiques. L'appareillage de détection est essentiellement constitué de deux bras symétriques non magnétiques en deux parties. La première s'intéresse seulement aux particules chargées : mesure de leur direction (chambres à fils scintillateurs) et identification des électrons (Cerenkov). La deuxième forme un calorimètre mesurant la position et l'énergie des photons et électrons (sandwiches plomb-scintillateur chambres proportionnelles à lecture cathodique et mur de verre au plomb). L'analyse des données est fondée sur la reconnaissance d'une paire d'électrons provenant d'un $\Psi$, puis la recherche du photon associé, déduit de la reconstruction de la cinématique de la désintégration du $\chi$. Un ensemble de 32 et 55 événements répondent à ses critères ont été isolés, respectivement pour le \chi_1$ et $\chi_2$, avec un bruit de fond négligeable, permettant d'extraire les valeurs de la masse, la largeur et le rapport de branchement $p\bar{p}$. Ces résultats sont comparés aux prévisions théoriques des modèles inspirés de la chromodynamique quantique (QCD) : les masses sont bien décrites par les méthodes de potentiel et de règles de somme (avec une incertitude de l'ordre de 10 MeV). Les prévisions sur les largeurs (calculées à l'ordre 0 de QCD) ne donnent que l'ordre de grandeur de nos résultats alors que celles concernant les rapports de branchement sont en bon accord avec nos mesures.

A gauged SU(4) flavor symmetric hadronic Lagrangian with empirical hadron masses is constructed to study charmonium absorption and charmed hadron production in hadronic reactions. For the coupling constants, empirical values are used if available. Otherwise, they are determined from known coupling constants using the SU(4) relations. To take into account the finite sizes of hadrons, form factors are introduced at strong interaction vertices with empirical cutoff parameters. For J/ψabsorption by nucleons, we have included both two-and three-body final states and find that with a cutoff parameter of 1 GeV at interaction vertices involving charm hadrons, the cross section is at most 5 mb and is consistent with that extracted from J/ψproduction from both photo-and proton-nucleus reactions. We have also evaluated the cross sections for charmed hadron production from pion and rho meson interactions with nucleons. With the same cutoff parameter of 1 GeV at interaction vertices, we find that these cross sections have values of a few tenths of mb and are dominated bythe s-channel nucleon pole diagram. For charmed hadron production from proton-proton reactions, their cross sections including bothtwo-andthree-body final states are about 1 batcenter-of-mass energyof 11.5 GeV, which is comparable to the measured inclusive cross section in these reactions.Including photon as a U(1) gauge particle, we have extended the model to study charmed hadron production in photon-proton reactions with both two-and three-body final states included. For form factors, an overall one is introduced in each processin order to maintain the gauge invariance of the total amplitude. Fitting the cutoff parameter in the form factor to the measured total cross section for charmed hadron production in photon-proton reactions at a center-of-mass energy of 6 GeV, the ratio of the cross sections for two-body and three-body final states is consistent with available experimental data.This result is further compared with predictions from the leading-order perturbative QCD calculation. Knowledge of the cross sections for charmonium absorption byhadrons and for charmed hadron production in hadronic reactions is essential for understanding charm production in heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC), where a quark-gluon plasma is expected to be formed during the initial hot dense stage.

No description available.

No description available.