Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userDecay behaviors of the $P_c$ hadronic molecules
117
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
In this proceeding, we present our recent work on decay behaviors of the $P_c$ hadronic molecules, which can help to disentangle the nature of the two $P_c$ pentaquark-like structures. The results turn out that the relative ratio of the decays of $P^+_c(4380)$ to $bar{D}^* Lambda_c$ and $J/psi p$ is very different for $P_c$ being a $bar D^*Sigma_c$ or $bar DSigma_c^*$ bound state with $J^P=frac{3}{2}^-$. And from the total decay width, we find that $P_c(4380)$ being a $bar DSigma_c^*$ molecule state with $J^P=frac{3}{2}^-$ and $P_c(4450)$ being a $bar D^*Sigma_c$ molecule state with $J^P=frac{5}{2}^+$ is more favorable to the experimental data.
rate research
Read More
The $P_c(4380)$ and $P_c(4450)$ states observed recently by LHCb experiment were proposed to be either $bar{D} Sigma_c^*$ or $bar{D}^* Sigma_c$ S-wave bound states of spin parity $J^P={frac32}^-$. We analyze the decay behaviors of such two types of hadronic molecules within the effective Lagrangian framework. With branching ratios of ten possible decay channels calculated, it is found that the two types of hadronic molecules have distinguishable decay patterns. While the $bar{D} Sigma_c^*$ molecule decays dominantly to $bar{D}^* Lambda_c$ channel with a branching ratio by 2 orders of magnitude larger than to $bar{D}Lambda_c$, the $bar{D}^* Sigma_c$ molecule decays to these two channels with a difference of less than a factor of 2. Our results show that the total decay width of $P_c(4380)$ as the spin-parity-${frac32}^-$ $bar{D} Sigma_c^*$ molecule is about a factor of 2 larger than the corresponding value for the $bar{D}^* Sigma_c$ molecule. It suggests that the assignment of $bar{D} Sigma_c^*$ molecule for $P_c(4380)$ is more favorable than the $bar{D}^* Sigma_c$ molecule. In addition, $P_c(4450)$ seems to be a $bar{D}^* Sigma_c$ molecule with $J^P={frac52}^+$ in our scheme. Based on these partial decay widths of $P_c(4380)$, we estimate the cross sections for the reactions $gamma p to J/psi p $ and $ pi pto J/psi p $ through the s-channel $P_c(4380)$ state. The forthcoming $gamma p$ experiment at JLAB and $pi p$ experiment at JPARC should be able to pin down the nature of these $P_c$ states.
In a chromomagnetic model, we analyse the properties of the newly observed $P_c(4457)^+$, $P_c(4440)^+$, and $P_c(4312)^+$ states. We estimate the masses of the $(uud)_{8_c}(cbar{c})_{8_c}$ and $(uds)_{8_c}(cbar{c})_{8_c}$ pentaquark states by considering the isospin breaking effects. Their values are determined by calculating mass distances from the $Sigma_c^{++}D^-$ and $Xi_c^{prime+}D^-$ thresholds, respectively. It is found that the isospin breaking effects on the spectrum are small. From the uncertainty consideration and the rearrangement decay properties in a simple model, we find that it is possible to assign the $P_c(4457)^+$, $P_c(4440)^+$, and $P_c(4312)^+$ as $J^P=3/2^-$, $1/2^-$, and $3/2^-$ pentaquark states, respectively. The assignment in the molecule picture can be different, in particular for the $P_c(4312)^+$. The information from open-charm channels, e.g. ${cal B}[P_ctoSigma_c^{++}D^-]/{cal B}[P_cto J/psi p]$, will play an important role in distinguishing the inner structures of the $P_c$ states. Discussions and predictions based on the calculations are also given.
The 2015 LHCb discovery of a structure (denoted by $P_c^+$) decaying in $J/psi ,p$ and conjectured to be a penta-quark state, has triggered a renewed interest in the question of possible existence of multi-quark states not predicted by the naive quark model. In this talk we present some considerations on $P_c$ photo-production experiments, aimed at testing its multi-quark interpretation in the framework of a 40-years-old string-junction picture that allows a unified description of baryons, tetra-, and penta-quark states.
There are eighteen possibly existing $D^{(*)} bar D^{(*)}$, $D^{(*)} bar K^{(*)}$, and $D^{(*)} D_s^{(*)-}$ hadronic molecular states. We construct their corresponding interpolating currents, and calculate their masses and decay constants using QCD sum rules. Based on these results, we calculate their relative production rates in $B$ and $B^*$ decays through the current algebra, and calculate their relative branching ratios through the Fierz rearrangement, as summarized in Table III. Our results support the interpretations of the $X(3872)$, $Z_c(3900)$, $Z_c(4020)$, and $X_0(2900)$ as the molecular states $D bar D^*$ of $J^{PC} = 1^{++}$, $D bar D^*$ of $J^{PC} = 1^{+-}$, $D^* bar D^*$ of $J^{PC} = 1^{+-}$, and $D^* bar K^*$ of $J^P = 0^{+}$, respectively. Our results also suggest that the $Z_{cs}(3985)$, $Z_{cs}(4000)$, and $Z_{cs}(4220)$ are strange partners of the $X(3872)$, $Z_c(3900)$, and $Z_c(4020)$, respectively. In the calculations we estimate the lifetime of a weakly-coupled composite particle $A = |BCrangle$ to be $1/t_A approx 1/t_B + 1/t_C + Gamma_{A to BC} + cdots$, with $cdots$ partial widths of other possible decay channels.
We study the newly reported hidden-charm pentaquark candidates $P_c(4312)$, $P_c(4440)$ and $P_c(4457)$ from the LHCb Collaboration, in the framework of the effective-range expansion and resonance compositeness relations. The scattering lengths and effective ranges from the $S$-wave $Sigma_cbar{D}$ and $Sigma_cbar{D}^*$ scattering are calculated by using the experimental results of the masses and widths of the $P_c(4312)$, $P_c(4440)$ and $P_c(4457)$. Then we calculate the couplings between the $J/psi p,,Sigma_cbar{D}$ channels and the pentaquark candidate $P_c(4312)$, with which we further estimate the probabilities of finding the $J/psi p$ and $Sigma_cbar{D}$ components inside $P_c(4312)$. The partial decay widths and compositeness coefficients are calculated for the $P_c(4440)$ and $P_c(4457)$ states by including the $J/psi p$ and $Sigma_cbar{D}^*$ channels. Similar studies are also carried out for the three $P_c$ states by including the $Lambda_cbar{D}^{*}$ and $Sigma_cbar{D}^{(*)}$ channels.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
