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Register a new userA possible NN*(1440) quasi-molecular state
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Inspired by the recent observation of a narrow resonance-like structure around 2360 MeV in the p+n to d + pi 0 + pi 0 cross section, the possibility of forming a NN*(1440) quasi-molecular state is investigated by using a meson exchange model in which the pi, sigma, rho and omega exchanges in t- and u-channels are considered. By adopting the coupling constants extracted from the relevant NN scattering and N*(1440) decay data, it is found that a deuteron-like quasi-molecular state of NN*(1440) with a binding energy in the range of from 2 to 67MeV can be formed. Therefore, it is speculated that the observed structure around 2360 MeV might be or may have a large component of the NN*(1440) quasi-molecular state.
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The structure of Omega-pi state with isospin I=1 and spin-parity J^p=3/2^- are dynamically studied in both the chiral SU(3) quark model and the extended chiral SU(3) quark model by solving a resonating group method (RGM) equation. The model parameters are taken from our previous work, which gave a satisfactory description of the energies of the baryon ground states, the binding energy of the deuteron, the nucleon-nucleon (NN) scattering phase shifts, and the hyperon-nucleon (YN) cross sections. The calculated results show that the Omega-pi state has an attractive interaction, and in the extended chiral SU(3) quark model such an attraction can make for an Omega-pi quasi-bound state with the binding energy of about several MeV.
We study the photoproduction of the $N(1440)$ resonance in $gamma^*pto N^*$ process in quark models, where the $N(1440)$ takes different wave functions: first radial excitation of the nucleon imported from low-lying baryon mass spectrum calculations, a general radial excitation of the nucleon, and a $q^3$ state with positive parity. The comparison between the theoretical results and experimental data on the helicity amplitudes $A_{1/2}$ and $S_{1/2}$ and the analysis of the spatial wave function of the $N(1440)$ resonance reveal that the $N(1440)$ resonance is mainly the $q^3$ first radial excitation.
Assuming the newly observed $Z_c(3900)$ to be a molecular state of $Dbar D^*(D^{*} bar D)$, we calculate the partial widths of $Z_c(3900)to J/psi+pi;; psi+pi;; eta_c+rho$ and $Dbar D^*$ within the light front model (LFM). $Z_c(3900)to J/psi+pi$ is the channel by which $Z_c(3900)$ was observed, our calculation indicates that it is indeed one of the dominant modes whose width can be in the range of a few MeV depending on the model parameters. Similar to $Z_b$ and $Z_b$, Voloshin suggested that there should be a resonance $Z_c$ at 4030 MeV which can be a molecular state of $D^*bar D^*$. Then we go on calculating its decay rates to all the aforementioned final states and as well the $D^*bar D^*$. It is found that if $Z_c(3900)$ is a molecular state of ${1oversqrt 2}(Dbar D^*+D^*bar D)$, the partial width of $Z_c(3900)to Dbar D^*$ is rather small, but the rate of $Z_c(3900)topsi(2s)pi$ is even larger than $Z_c(3900)to J/psipi$. The implications are discussed and it is indicated that with the luminosity of BES and BELLE, the experiments may finally determine if $Z_c(3900)$ is a molecular state or a tetraquark.
Recently a vector charmonium-like state $Y(4626)$ was observed in the portal of $D^+_sD_{s1}(2536)^-$. It intrigues an active discussion on the structure of the resonance because it has obvious significance for gaining a better understanding on its hadronic structure with suitable inner constituents. It indeed concerns the general theoretical framework about possible structures of exotic states. Since the mass of $Y(4626)$ is slightly above the production threshold of $D^+_sbar D_{s1}(2536)^-$ whereas below that of $D^*_sbar D_{s1}(2536)$ with the same quark contents as that of $D^+_sbar D_{s1}(2536)^-$, it is natural to conjecture $Y(4626)$ to be a molecular state of $D^{*}_sbar D_{s1}(2536)$, as suggested in literature. Confirming or negating this allegation would shed light on the goal we concern. We calculate the mass spectrum of a system composed of a vector meson and an axial vector i.e. $D^*_sbar D_{s1}(2536)$ within the framework of the Bethe-Salpeter equations. Our numerical results show that the dimensionless parameter $lambda$ in the form factor which is phenomenologically introduced to every vertex, is far beyond the reasonable range for inducing an even very small binding energy $Delta E$. It implies that the $D^*_sbar D_{s1}(2536)$ system cannot exist in the nature as a hadronic molecule in this model, so that we may not think the resonance $Y(4626)$ to be a bound state of $D^*_sbar D_{s1}(2536)$, but something else, for example a tetraquark and etc.
We propose a quantum storage scheme independent of the current time-control schemes, and study a quantum data bus (transmission line resonator) in a hybrid system consisting of a circuit QED system integrated with a cold molecular ensemble. Here, an effective interaction between charge qubit and molecule is mediated by the off-resonate field in the data bus. Correspondingly, the charge state can be mapped into the collective quasi-spin state of the molecular ensemble via the standard dark state based adiabatic manipulation.
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