Isospin breaking effects in the X(3872) resonance

In this paper we study the effects of isospin breaking in the dynamical generation of the X(3872) state. We also calculate the ratio of the branching fractions of the $X$ decaying into $J/\psi$ with two and three pions, which has been measured experimentally to be close to unity. Together with the X(3872), of positive C-parity, we predict the existence of a negative C-parity state and we comment on which decay channel is more promising to observe this state.Comment: 10 pages, 6 figures, study on the line shape of the X(3872) adde

Radiative decays of the Y(3940), Z(3930) and the X(4160) as dynamically generated resonances

We study the radiative decay properties of the charmonium-like X, Y and Z mesons generated dynamically from vector meson-vector meson interaction in the framework of a unitarized hidden-gauge formalism. In the present work we calculate the one- and two-photon decay widths of the hidden-charm Y(3940), Z(3930) (or X(3915)) and X(4160) mesons in the framework of the vector meson dominance formalism. We obtain good agreement with experiment in case of the two photon width of the X(3915) which we associate with the $2^+$ resonance that we find at 3922 MeV.Comment: 13 pages, 3 figure

Further Theoretical Analysis on the K−3He→ΛpnK^{-} {}^{3} \text{He} \to \Lambda p n Reaction for the KˉNN\bar{K} N N Bound-State Search in the J-PARC E15 Experiment

Based on the scenario that a $\bar{K} N N$ bound state is generated and it eventually decays into $\Lambda p$, we calculate the cross section of the $K^{-} {}^{3} \text{He} \to \Lambda p n$ reaction, which was recently measured in the J-PARC E15 experiment. We find that the behavior of the calculated differential cross section $d ^{2} \sigma / d M_{\Lambda p} d q_{\Lambda p}$, where $M_{\Lambda p}$ and $q_{\Lambda p}$ are the $\Lambda p$ invariant mass and momentum transfer in the $(K^{-} , \, n)$ reaction in the laboratory frame, respectively, is consistent with the experiment. Furthermore, we can reproduce almost quantitatively the experimental data of the $\Lambda p$ invariant mass spectrum in the momentum transfer window $350 \text{ MeV} /c < q_{\Lambda p} < 650 \text{ MeV} /c$. These facts strongly suggest that the $\bar{K} N N$ bound state was indeed generated in the J-PARC E15 experiment.Comment: 4 pages, 4 EPS figures, talk given at the 8th International Conference on Quarks and Nuclear Physics (QNP2018), Tsukuba, Japan, 13-17 November, 201

Semileptonic decay of Bc−B^{-}_c into X(3930)X(3930), X(3940)X(3940), X(4160)X(4160)

We study the semileptonic decay of $B^{-}_c$ meson into $\bar{\nu} l^-$ and the isospin zero $X(3930)~(2^{++})$, $X(3940)~(0^{++})$, $X(4160)~(2^{++})$ resonances. We look at the reaction from the perspective that these resonaces appear as dynamically generated from the vector-vector interaction in the charm sector, and couple strongly to $D^{*}\bar{D^{*}}$ and $D^{*}_{s}\bar{D_{s}^{*}}$. We also look into the $B^{-}_c \rightarrow \bar{\nu}_{l} l^- D^{*}\bar{D^{*}}$ and $B^{-}_c \rightarrow \bar{\nu}_{l} l^- D^{*}_{s}\bar{D_{s}^{*}}$ reactions close to threshold and relate the $D^{*}\bar{D^{*}}$ and $D^{*}_{s}\bar{D_{s}^{*}}$ mass distribution to the rate of production of the $X$ resonances.Comment: 7 pages, 9 figure