Starting from the molecular picture for the  $$D_{s1}(2460)$$  <math> <mrow> <msub> <mi>D</mi> <mrow> <mi>s</mi> <mn>1</mn> </mrow> </msub> <mrow> <mo>(</mo> <mn>2460</mn> <mo>)</mo> </mrow> </mrow> </math>   and  $$D_{s1}(2536)$$  <math> <mrow> <msub> <mi>D</mi> <mrow> <mi>s</mi> <mn>1</mn> </mrow> </msub> <mrow> <mo>(</mo> <mn>2536</mn> <mo>)</mo> </mrow> </mrow> </math>   resonances, which are dynamically generated by the interaction of coupled channels, the most important of which are the  $$D^*K$$  <math> <mrow> <msup> <mi>D</mi> <mo>∗</mo> </msup> <mi>K</mi> </mrow> </math>   for the  $$D_{s1}(2460)$$  <math> <mrow> <msub> <mi>D</mi> <mrow> <mi>s</mi> <mn>1</mn> </mrow> </msub> <mrow> <mo>(</mo> <mn>2460</mn> <mo>)</mo> </mrow> </mrow> </math>   and  $$DK^*$$  <math> <mrow> <mi>D</mi> <msup> <mi>K</mi> <mo>∗</mo> </msup> </mrow> </math>   for the  $$D_{s1}(2536)$$  <math> <mrow> <msub> <mi>D</mi> <mrow> <mi>s</mi> <mn>1</mn> </mrow> </msub> <mrow> <mo>(</mo> <mn>2536</mn> <mo>)</mo> </mrow> </mrow> </math>  , we evaluate the ratio of decay widths for the  $$\bar{B}_s^0 \rightarrow D_{s1}(2460)^+ K^-$$  <math> <mrow> <msubsup> <mover> <mrow> <mi>B</mi> </mrow> <mrow> <mo>¯</mo> </mrow> </mover> <mi>s</mi> <mn>0</mn> </msubsup> <mo>→</mo> <msub> <mi>D</mi> <mrow> <mi>s</mi> <mn>1</mn> </mrow> </msub> <msup> <mrow> <mo>(</mo> <mn>2460</mn> <mo>)</mo> </mrow> <mo>+</mo> </msup> <msup> <mi>K</mi> <mo>-</mo> </msup> </mrow> </math>   and  $$\bar{B}_s^0 \rightarrow D_{s1}(2536)^+ K^-$$  <math> <mrow> <msubsup> <mover> <mrow> <mi>B</mi> </mrow> <mrow> <mo>¯</mo> </mrow> </mover> <mi>s</mi> <mn>0</mn> </msubsup> <mo>→</mo> <msub> <mi>D</mi> <mrow> <mi>s</mi> <mn>1</mn> </mrow> </msub> <msup> <mrow> <mo>(</mo> <mn>2536</mn> <mo>)</mo> </mrow> <mo>+</mo> </msup> <msup> <mi>K</mi> <mo>-</mo> </msup> </mrow> </math>   decays, the latter of which has been recently investigated by the LHCb collaboration, and we obtain a ratio of the order of unity. The present results should provide an incentive for the related decay into the  $$D_{s1}(2460)$$  <math> <mrow> <msub> <mi>D</mi> <mrow> <mi>s</mi> <mn>1</mn> </mrow> </msub> <mrow> <mo>(</mo> <mn>2460</mn> <mo>)</mo> </mrow> </mrow> </math>   resonance to be performed, which would provide valuable information on the nature of these two resonances.

China

Jia-Xin Lin

Hua-Xing Chen

Wei-Hong Liang

Chu-Wen Xiao

Spain

Eulogio Oset

$$\bar{B}_s^0 \rightarrow D_{s1}(2460)^+ K^-, D_{s1}(2536)^+ K^-$$  <math> <mrow> <msubsup> <mover> <mrow> <mi>B</mi> </mrow> <mrow> <mo>¯</mo> </mrow> </mover> <mi>s</mi> <mn>0</mn> </msubsup> <mo>→</mo> <msub> <mi>D</mi> <mrow> <mi>s</mi> <mn>1</mn> </mrow> </msub> <msup> <mrow> <mo>(</mo> <mn>2460</mn> <mo>)</mo> </mrow> <mo>+</mo> </msup> <msup> <mi>K</mi> <mo>-</mo> </msup> <mo>,</mo> <msub> <mi>D</mi> <mrow> <mi>s</mi> <mn>1</mn> </mrow> </msub> <msup> <mrow> <mo>(</mo> <mn>2536</mn> <mo>)</mo> </mrow> <mo>+</mo> </msup> <msup> <mi>K</mi> <mo>-</mo> </msup> </mrow> </math>   and the nature of the two  $$D_{s1}$$  <math> <msub> <mi>D</mi> <mrow> <mi>s</mi> <mn>1</mn> </mrow> </msub> </math>   resonances

We perform a theoretical study of the  $$J/\psi \rightarrow \omega (\phi ) K^* \bar{K} + c.c. \rightarrow \omega (\phi ) K^0 \pi ^+ K^-$$  <math> <mrow> <mi>J</mi> <mo>/</mo> <mi>ψ</mi> <mo>→</mo> <mi>ω</mi> <mrow> <mo>(</mo> <mi>ϕ</mi> <mo>)</mo> </mrow> <msup> <mi>K</mi> <mo>∗</mo> </msup> <mover> <mrow> <mi>K</mi> </mrow> <mrow> <mo>¯</mo> </mrow> </mover> <mo>+</mo> <mi>c</mi> <mo>.</mo> <mi>c</mi> <mo>.</mo> <mo>→</mo> <mi>ω</mi> <mrow> <mo>(</mo> <mi>ϕ</mi> <mo>)</mo> </mrow> <msup> <mi>K</mi> <mn>0</mn> </msup> <msup> <mi>π</mi> <mo>+</mo> </msup> <msup> <mi>K</mi> <mo>-</mo> </msup> </mrow> </math>   reactions with the assumption that the  $$f_1(1285)$$  <math> <mrow> <msub> <mi>f</mi> <mn>1</mn> </msub> <mrow> <mo>(</mo> <mn>1285</mn> <mo>)</mo> </mrow> </mrow> </math>   is dynamically generated from a single channel  $$K^* \bar{K} + c.c$$  <math> <mrow> <msup> <mi>K</mi> <mo>∗</mo> </msup> <mover> <mrow> <mi>K</mi> </mrow> <mrow> <mo>¯</mo> </mrow> </mover> <mo>+</mo> <mi>c</mi> <mo>.</mo> <mi>c</mi> </mrow> </math>   interaction in the chiral unitary approach. Two peaks in the  $$K^0 \pi ^+ K^-$$  <math> <mrow> <msup> <mi>K</mi> <mn>0</mn> </msup> <msup> <mi>π</mi> <mo>+</mo> </msup> <msup> <mi>K</mi> <mo>-</mo> </msup> </mrow> </math>   invariant mass distribution are observed, one clear peak locates at the  $$f_1(1285)$$  <math> <mrow> <msub> <mi>f</mi> <mn>1</mn> </msub> <mrow> <mo>(</mo> <mn>1285</mn> <mo>)</mo> </mrow> </mrow> </math>   nominal mass, the other peak locates at around  $$1420 \text {MeV}$$  <math> <mrow> <mn>1420</mn> <mtext>MeV</mtext> </mrow> </math>   with about  $$70 \text {MeV}$$  <math> <mrow> <mn>70</mn> <mtext>MeV</mtext> </mrow> </math>   width. We conclude that the former peak is associated with the  $$f_1(1285)$$  <math> <mrow> <msub> <mi>f</mi> <mn>1</mn> </msub> <mrow> <mo>(</mo> <mn>1285</mn> <mo>)</mo> </mrow> </mrow> </math>   and the latter peak is not a genuine resonance but a manifestation of the kinematic effect in the higher energy region caused by the  $$K^* \bar{K} + c.c.$$  <math> <mrow> <msup> <mi>K</mi> <mo>∗</mo> </msup> <mover> <mrow> <mi>K</mi> </mrow> <mrow> <mo>¯</mo> </mrow> </mover> <mo>+</mo> <mi>c</mi> <mo>.</mo> <mi>c</mi> <mo>.</mo> </mrow> </math>   decay mode of the  $$f_1(1285)$$  <math> <mrow> <msub> <mi>f</mi> <mn>1</mn> </msub> <mrow> <mo>(</mo> <mn>1285</mn> <mo>)</mo> </mrow> </mrow> </math>  .

Jia-Ting Li

$$\varvec{J/\psi }$$  <math> <mrow> <mi>J</mi> <mo>/</mo> <mi>ψ</mi> </mrow> </math>   decays into  $$\omega (\phi ) f_1(1285)$$  <math> <mrow> <mi>ω</mi> <mrow> <mo>(</mo> <mi>ϕ</mi> <mo>)</mo> </mrow> <msub> <mi>f</mi> <mn>1</mn> </msub> <mrow> <mo>(</mo> <mn>1285</mn> <mo>)</mo> </mrow> </mrow> </math>   and  $$\omega (\phi ) ``f_1(1420)$$  <math> <mrow> <mi>ω</mi> <mrow> <mo>(</mo> <mi>ϕ</mi> <mo>)</mo> </mrow> <mo>`</mo> <mo>`</mo> <msub> <mi>f</mi> <mn>1</mn> </msub> <mrow> <mo>(</mo> <mn>1420</mn> <mo>)</mo> </mrow> </mrow> </math>  ”

We study the   $\bar B_s^0 \to J/\psi f_0(980)$   and   $\bar B_s^0 \to J/\psi f_0(980)$   reactions, and pay attention to the different sources of isospin violation and mixing of   $\bar B_s^0 \to J/\psi f_0(980)$   and   $\bar B_s^0 \to J/\psi f_0(980)$   resonances where these resonances are dynamically generated from meson–meson interactions. We find that the main cause of isospin violation is isospin breaking in the meson–meson transition T matrices, and the other source is that the loops involving kaons in the production mechanism do not cancel due to the different masses of charged and neutral kaons. We obtain a branching ratio for   $\bar B_s^0 \to J/\psi f_0(980)$   production of the order of   $\bar B_s^0 \to J/\psi f_0(980)$  . Future experiments can address this problem, and the production rate and shape of the   $\bar B_s^0 \to J/\psi f_0(980)$   mass distribution will definitely help to better understand the nature of scalar resonances.

Gong-Jie Zhang

E. Oset

The Decay and the Mixing  

We perform a study of the  $$D_s^+ \rightarrow a_0(980)(f_0(980)) e^+ \nu _e$$  <math> <mrow> <msubsup> <mi>D</mi> <mi>s</mi> <mo>+</mo> </msubsup> <mo>→</mo> <msub> <mi>a</mi> <mn>0</mn> </msub> <mrow> <mo>(</mo> <mn>980</mn> <mo>)</mo> </mrow> <mrow> <mo>(</mo> <msub> <mi>f</mi> <mn>0</mn> </msub> <mrow> <mo>(</mo> <mn>980</mn> <mo>)</mo> </mrow> <mo>)</mo> </mrow> <msup> <mi>e</mi> <mo>+</mo> </msup> <msub> <mi>ν</mi> <mi>e</mi> </msub> </mrow> </math>   reactions investigating the different sources of isospin violation which make the production of the  $$a_0(980)$$  <math> <mrow> <msub> <mi>a</mi> <mn>0</mn> </msub> <mrow> <mo>(</mo> <mn>980</mn> <mo>)</mo> </mrow> </mrow> </math>   possible. We find that loops involving kaons in the production mechanism provide a source of isospin violation since they do not cancel due to the different mass of charged and neutral kaons, but we also find that the main source comes from the breaking of isospin in the meson-meson transition T matrices, which contain information on the nature of the low lying scalar mesons. The reaction is thus very sensitive to the nature of the  $$a_0(980)$$  <math> <mrow> <msub> <mi>a</mi> <mn>0</mn> </msub> <mrow> <mo>(</mo> <mn>980</mn> <mo>)</mo> </mrow> </mrow> </math>   and  $$f_0(980)$$  <math> <mrow> <msub> <mi>f</mi> <mn>0</mn> </msub> <mrow> <mo>(</mo> <mn>980</mn> <mo>)</mo> </mrow> </mrow> </math>   resonances. Our results are consistent with the present upper bound for  $$a_0(980)$$  <math> <mrow> <msub> <mi>a</mi> <mn>0</mn> </msub> <mrow> <mo>(</mo> <mn>980</mn> <mo>)</mo> </mrow> </mrow> </math>   production and only a factor three smaller, indicating that future runs with more statistics should find actual numbers for this reaction from where we can learn more about the origin of the scalar resonances and their nature.

Sheng-Juan Jiang

The  $$D_s^+ \rightarrow a_0(980) e^+ \nu _e$$  <math> <mrow> <msubsup> <mi>D</mi> <mi>s</mi> <mo>+</mo> </msubsup> <mo>→</mo> <msub> <mi>a</mi> <mn>0</mn> </msub> <mrow> <mo>(</mo> <mn>980</mn> <mo>)</mo> </mrow> <msup> <mi>e</mi> <mo>+</mo> </msup> <msub> <mi>ν</mi> <mi>e</mi> </msub> </mrow> </math>   reaction and the  $$a_0(980)-f_0(980)$$  <math> <mrow> <msub> <mi>a</mi> <mn>0</mn> </msub> <mrow> <mo>(</mo> <mn>980</mn> <mo>)</mo> </mrow> <mo>-</mo> <msub> <mi>f</mi> <mn>0</mn> </msub> <mrow> <mo>(</mo> <mn>980</mn> <mo>)</mo> </mrow> </mrow> </math>   mixing