No Arabic abstract
Charmed dibaryon states with the spin-parity $J^{pi}=0^+$, $1^+$, and $2^+$are predicted for the two-body $Y_cN$ ($=Lambda_c$, $Sigma_c$, or $Sigma^*_c$) systems. We employ the complex scaling method for the coupled channel Hamiltonian with the $Y_cN$-CTNN potentials, which were proposed in our previous study. We find four sharp resonance states near the $Sigma_c N$ and $Sigma^*_c N$ thresholds. From the analysis of the binding energies of partial channel systems, we conclude that these resonance states are Feshbach resonances. We compare the results with the $Y_c N$ resonance states in the heavy quark limit, where the $Sigma_c N$ and $Sigma^*_c N$ thresholds are degenerate, and find that they form two pairs of the heavy-quark doublets in agreement with the heavy quark spin symmetry.
We study charmed baryon resonances that are generated dynamically from a coupled-channel unitary approach that implements heavy-quark symmetry. Some states can already be identified with experimental observations, such as $Lambda_c(2595)$, $Lambda_c(2660)$, $Sigma_c(2902)$ or $Lambda_c(2941)$, while others need a compilation of more experimental data as well as an extension of the model to include higher order contributions. We also compare our model to previous SU(4) schemes.
We determine the hard-loop resummed propagator in an anisotropic QCD plasma in general covariant gauges and define a potential between heavy quarks from the Fourier transform of its static limit. We find that there is stronger attraction on distance scales on the order of the inverse Debye mass for quark pairs aligned along the direction of anisotropy than for transverse alignment.
We suggest that the recently observed charmed scalar mesons $D_0^{0}(2308)$ (BELLE) and $D_0^{0,+}(2405)$ (FOCUS) are considered as different resonances. Using the QCD sum rule approach we investigate the possible four-quark structure of these mesons and also of the very narrow $D_{sJ}^{+}(2317)$, firstly observed by BABAR. We use diquak-antidiquark currents and work to the order of $m_s$ in full QCD, without relying on $1/m_c$ expansion. Our results indicate that a four-quark structure is acceptable for the resonances observed by BELLE and BABAR: $D_0^{0}(2308)$ and $D_{sJ}^{+}(2317)$ respectively, but not for the resonances observed by FOCUS: $D_0^{0,+}(2405)$.
Heavy-flavour quarks are predominantly produced in hard scatterings on a short time-scale and traverse the medium interacting with its constituents, thus they are one of the effective probes of the transport properties of the medium formed in relativistic heavy ion collisions. On the other hand, the thermal production of heavy-flavour quarks in quark-gluon plasma (QGP) is itself of interest. In this report, the production and elliptic flow of the prompt charmed mesons $D^0$, $D^+$, $D^{*+}$ and $J/psi$ in PbPb collisions at the center-of-mass energy 2.76 TeV per nucleon pair are described in the framework of two-component HYDJET++ model. The model combines thermal and pQCD production mechanisms. The spectra and elliptic flow of charmed mesons are presented, the results are compared with LHC data.
We look for $DeltaDelta$ and $NDelta$ resonances by calculating $NN$ scattering phase shifts of two interacting baryon clusters of quarks with explicit coupling to these dibaryon channels. Two phenomenological nonrelativistic chiral quark models giving similar low-energy $NN$ properties are found to give significantly different dibaryon resonance structures. In the chiral quark model (ChQM), the dibaryon system does not resonate in the $NN$ $S$-waves, in agreement with the experimental SP07 $NN$ partial-wave scattering amplitudes. In the quark delocalization and color screening model (QDCSM), the $S$-wave NN resonances disappear when the nucleon size $b$ falls below 0.53 fm. Both quark models give an $IJ^P = 03^+$ $DeltaDelta$ resonance. At $b=0.52 $fm, the value favored by baryon spectrum, the resonance mass is 2390 (2420) MeV for the ChQM with quadratic (linear) confinement, and 2360 MeV for the QDCSM. Accessible from the $^3D_3^{NN}$ channel, this resonance is a promising candidate for the known isoscalar ABC structure seen more clearly in the $pn$$to $$dpipi$ production cross section at 2410 MeV in the recent preliminary data reported by the CELSIUS-WASA Collaboration. In the isovector dibaryon sector, our quark models give a bound or almost bound $^5S_2^{DeltaDelta}$ state that can give rise to a $^1D_2^{NN}$ resonance. None of the quark models used has bound $NDelta$ $P$-states that might generate odd-parity resonances.