0000000000800350
AUTHOR
Marina Nielsen
Weak decays of heavy hadrons into dynamically generated resonances
In this paper, we present a review of recent works on weak decay of heavy mesons and baryons with two mesons, or a meson and a baryon, interacting strongly in the final state. The aim is to learn about the interaction of hadrons and how some particular resonances are produced in the reactions. It is shown that these reactions have peculiar features and act as filters for some quantum numbers which allow to identify easily some resonances and learn about their nature. The combination of basic elements of the weak interaction with the framework of the chiral unitary approach allow for an interpretation of results of many reactions and add a novel information to different aspects of the hadron…
Ds0⁎±(2317)and KD scattering fromBs0decay
We study the B¯s0→Ds−(KD)+ weak decay, and look at the KD invariant mass distribution, for which we use recent lattice QCD results for the KD interaction from where the Ds0⁎(2317) resonance appears as a KD bound state. Since there are not yet experimental data on this reaction, in a second step we propose an analysis method to obtain information on the Ds0⁎(2317) resonance from the future experimental KD mass distribution in this decay. For this purpose, we generate synthetic data taking a few points from our theoretical distribution, to which we add a 5% or 10% error. With this analysis method, we prove that one can obtain from these “data” the existence of a bound KD state, the KD scatter…
Heavy quarkonium: progress, puzzles, and opportunities
A golden age for heavy quarkonium physics dawned a decade ago, initiated by the confluence of exciting advances in quantum chromodynamics (QCD) and an explosion of related experimental activity. The early years of this period were chronicled in the Quarkonium Working Group (QWG) CERN Yellow Report (YR) in 2004, which presented a comprehensive review of the status of the field at that time and provided specific recommendations for further progress. However, the broad spectrum of subsequent breakthroughs, surprises, and continuing puzzles could only be partially anticipated. Since the release of the YR, the BESII program concluded only to give birth to BESIII; the $B$-factories and CLEO-c flo…
Exploring the D* rho system within QCD sum rules
We present a study of the D* rho system made by using the method of QCD sum rules to determine the mass of possible resonances generated in the same system. Using isospin and spin projectors, we investigate the different configurations and obtain evidences for three D* mesons with isospin I = 1/2, spin S = 0, 1, 2 and with masses 2500 +/- 67, 2523 +/- 60, and 2439 +/- 119 MeV, respectively. The last state can be associated with D-2*(2460) ( spin 2) listed by the Particle Data Group, while one of the first two might be related to D* (2640), with unknown spin parity. In the case of I = 3/2 we also find evidences of three states with spin 0, 1, and 2, respectively, with masses 2467 +/- 82, 242…
Reanalysis of thee+e−→(D*D¯*)±π∓reaction and the claim for theZc(4025)resonance
In this paper we study the reaction ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{({D}^{*}{\overline{D}}^{*})}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\pi}}^{\ensuremath{\mp}}$ in which the BESIII collaboration has claimed the existence of a ${1}^{+}$ resonance, named ${Z}_{c}(4025)$, in the ${D}^{*}{\overline{D}}^{*}$ invariant mass spectrum with a mass around 4026 MeV and width close to 26 MeV . We determine the ${D}^{*}{\overline{D}}^{*}$ invariant mass distribution and find that although the explanation considered by the BESIII collaboration is plausible, there are others which are equally possible, like a ${2}^{+}$ resonance or a bound state. Even more, we find that the data …
Ds0⁎±(2317) and KD scattering from Bs0 decay
AbstractWe study the B¯s0→Ds−(KD)+ weak decay, and look at the KD invariant mass distribution, for which we use recent lattice QCD results for the KD interaction from where the Ds0⁎(2317) resonance appears as a KD bound state. Since there are not yet experimental data on this reaction, in a second step we propose an analysis method to obtain information on the Ds0⁎(2317) resonance from the future experimental KD mass distribution in this decay. For this purpose, we generate synthetic data taking a few points from our theoretical distribution, to which we add a 5% or 10% error. With this analysis method, we prove that one can obtain from these “data” the existence of a bound KD state, the KD…
The role of f0(1710) in the ϕω threshold peak of J/Ψ→γϕω
Abstract We study the process J / Ψ → γ ϕ ω , measured by the BES experiment, where a neat peak close to the ϕω threshold is observed and is associated to a scalar meson resonance around 1800 MeV. We make the observation that a scalar resonance coupling to ϕω unavoidably couples strongly to K K ¯ , but no trace of a peak is seen in the K K ¯ spectrum of the J / Ψ → γ K K ¯ at this energy. This serves us to rule out the interpretation of the observed peak as a signal of a new resonance. After this is done, a thorough study is performed on the production of a pair of vector mesons and how its interaction leads necessarily to a peak in the J / Ψ → γ ϕ ω reaction close to the ϕω threshold, due …
Study of the D*ρ system using QCD sum rules
In this talk I present a study of the $D^* \rho$ system made by using the method of QCD sum rules. Considering isospin and spin projectors, we investigate the different configurations and obtain three $D^*$ mesons with isospin $I=1/2$, spin $S=0$, $1$, $2$ and with masses $2500\pm 67$ MeV, $2523\pm60$ MeV, and $2439\pm119$ MeV, respectively. The last state can be related to $D^*_2(2460)$ (spin 2) listed by the Particle Data Group, while one of the first two might be associated with $D^*(2640)$, whose spin-parity is unknown. In the case of $I=3/2$ we also find evidences of three states with spin 0, 1 and 2, respectively, with masses $2467\pm82$ MeV, $2420\pm128$ MeV, and $2550\pm56$ MeV.
Quark-meson coupling model with constituent quarks: Exchange and pionic effects
The binding energy of nuclear matter including exchange and pionic effects is calculated in a quark-meson coupling model with massive constituent quarks. As in the case with elementary nucleons in QHD, exchange effects are repulsive. However, the coupling of the mesons directly to the quarks in the nucleons introduces a new effect on the exchange energies that provides an extra repulsive contribution to the binding energy. Pionic effects are not small. Implications of such effects on observables are discussed.
Prediction of anI=1DD¯*state and relationship to the claimedZc(3900),Zc(3885)
We study here the interaction of $D{\overline{D}}^{*}$ in the isospin $I=1$ channel in light of recent theoretical advances that allow us to combine elements of the local hidden gauge approach with heavy quark spin symmetry. We find that the exchange of light $q\overline{q}$ is Okubo-Zweig-Iizuka (OZI) suppressed and thus we concentrate on the exchange of heavy vectors and of two pion exchange. The latter is found to be small compared to the exchange of heavy vectors, which then determines the strength of the interaction. A barely $D{\overline{D}}^{*}$ bound state decaying into ${\ensuremath{\eta}}_{c}\ensuremath{\rho}$ and $\ensuremath{\pi}J/\ensuremath{\psi}$ is found. At the same time we…
$D_{s0}^{\ast\pm}(2317)$ and $KD$ scattering from $B^0_s$ decay
We study the $\bar{B}_s^0\to D_s^-(DK)^+$ weak decay, and look at the $DK$ invariant mass distribution with the aim of obtaining relevant information on the nature of the $D_{s0}^{\ast+}(2317)$ resonance. We make a simulation of the experiment using the actual mass of the $D_{s0}^{\ast+}(2317)$ resonance and recent lattice QCD relevant parameters of the $KD$ scattering amplitude. We then solve the inverse problem of obtaining the $KD$ amplitude from these synthetic data, to which we have added a 5\% or 10\% error. We prove that one can obtain from these "data" the existence of a bound $KD$ state, the $KD$ scattering length and effective range, and most importantly, the $KD$ probability in t…
Pentaquark decay width in QCD sum rules
In a diquark-diquark-antiquark picture of the pentaquark we study the decay $\Theta \rightarrow K^{+} n$ within the framework of QCD sum rules. After evaluation of the relevant three-point function, we extract the coupling $g_{\Theta nK}$ which is directly related to the pentaquark width. Restricting the decay diagrams to those with color exchange between the meson-like and baryon-like clusters reduces the coupling constant by a factor of four. Whereas a small decay width might be possible for a positive parity pentaquark, it seems difficult to explain the measured width for a pentaquark with negative parity.
The <FONT FACE=Symbol>d</font> Expansion and the Principle of Minimal Sensitivity
The d-expansion is a nonperturbative approach for field theoretic models wich combines the techniques of perturbation theory and the variational principle. Different ways of implemeting the principle of minimal sensitivity to the d-expansion produce in general different results for observables. For illustration we use the Nambu- Jona-Lasinio model for chiral symmetry restoration at finite density and compare results with those obtained with the Hartree-Fock approximation.