Searcharxiv⌕ Search

arXiv subjects

Mario Sanchez Sanchez

Publications and source records attributed to Mario Sanchez Sanchez.

3 recordsLinked to original sources
arXiv2019

Emergence of a complete heavy-quark spin symmetry multiplet: seven molecular pentaquarks in light of the latest LHCb analysis

A recent analysis by the LHCb collaboration suggests the existence of three narrow pentaquark-like states --- the $P_c(4312)$,$P_c(4440)$ and $P_c(4457)$ --- instead of just one in the previous analysis (the $P_c(4450)$). The closeness of the $P_c(4312)$ to the $\bar{D} Σ_c$ threshold and the $P_c(4440)$/$P_c(4457)$ to the $\bar{D}^* Σ_c$ one suggests a molecular interpretation of these resonances. We show that these three pentaquark-like resonances can be naturally accommodated in a contact-range effective field theory description that incorporates heavy-quark spin symmetry. This description leads to the prediction of all the seven possible S-wave heavy antimeson-baryon molecules (that is, there should be four additional molecular pentaquarks in addition to the $P_c(4312)$, $P_c(4440)$ and $P_c(4457)$), providing the first example of a heavy-quark spin symmetry molecular multiplet that is complete. If this is confirmed, it will not only give us an impressive example of the application of heavy-quark symmetries and effective field theories in hadron physics: it will also uncover a clear and powerful ordering principle for the molecular spectrum, reminiscent of the SU(3)-flavor multiplets to which the light hadron spectrum conforms.

hep-ph↗
arXiv2018

Heavy-Quark Symmetry Partners of the Pc(4450) Pentaquark

The spectrum of heavy-hadron molecules is constrained by heavy-quark symmetry in its different manifestations. Heavy-quark spin symmetry for instance connects the properties of the ground and excited states of heavy hadrons, while heavy-antiquark-diquark symmetry connects the properties of heavy antimesons ($\bar{D}$, $\bar{D}^*$) and doubly heavy baryons ($Ξ_{cc}$, $Ξ_{cc}^*$). A prediction of these symmetries is that if the $P_c(4450)$ is indeed a $\bar{D}^* Σ_c$ bound state, then there should be a series of $\bar{D}^* Σ_c^*$, $Ξ_{cc} Σ_c$, $Ξ_{cc}^* Σ_c$, $Ξ_{cc} Σ_c^*$ and $Ξ_{cc}^* Σ_c^*$ partners. The concrete application of heavy-quark spin symmetry indicates that, if the $P_c(4450)$ is a $\frac{3}{2}^{-}$ $\bar{D}^* Σ_c$ molecule, the existence of a $\frac{5}{2}^{-}$ $\bar{D}^* Σ_c^*$ partner with similar binding energy --- which we call $P_c(4515)$, given its expected mass --- is likely. Conversely, the application of heavy-antiquark-diquark symmetry indicates that the $0^+$ $Ξ_{cc} Σ_c$, $1^+$ $Ξ_{cc} Σ_c^*$, $2^+$ $Ξ_{cc}^* Σ_c$ and $3^+$ $Ξ_{cc}^* Σ_c^*$ molecules are likely to bind too, with binding energies in the $20-30\,{\rm MeV}$ range.

hep-ph↗
arXiv2018

Exotic Doubly Charmed Ds0*(2317)D and Ds1*(2460)D* Molecules

The $D_{s0}^*(2317) D$ and $D_{s1}^*(2460) D^*$ heavy meson systems can exchange a kaon that is emitted in S-wave owing to the opposite intrinsic parity of the $D_{s0}^*$($D_{s1}^*$) and $D$($D^*$) mesons. As a consequence of the mass difference of the $D_{s0}^*$($D_{s1}^*$) and $D$($D^*$) mesons, the range of the kaon exchange potential will be significantly longer than expected, corresponding to an effective mass of about $200\,{\rm MeV}$. The potential will be very strong: the strength of the interaction is proportional to $(m_{D_{s0}} - m_D)^2 / f_π^2$ and $(m_{D_{s1}} - m_{D^*})^2 / f_π^2$. This combination of range and strength almost guarantees the existence of $D_{s0}^*(2317) D$ and $D_{s1}^*(2460) D^*$ bound states with $J^P = 0^{-}$ and $J^P = 0^{-}, 2^{-}$ respectively. Concrete calculations indicate a binding energy of $5-15\,{\rm MeV}$ independently of $J^P$. The $D_{s0}^*(2317) D$ and $D_{s1}^*(2460) D^*$ molecules have manifestly exotic flavour quantum numbers: $C=2$, $S=1$ and $I=1/2$. We expect the existence of bottom counterparts composed of the $B B_{s0}$ and $B^* B_{s1}^*$ mesons, which will be more bound and have a richer spectrum that might include a shallow P-wave state and an excited S-wave state.

hep-ph↗