The $$\pi f_0(500)$$ decay of the $$a_1(1260)$$

We evaluate the $$a_1(1260) \rightarrow \pi \sigma (f_0(500))$$ a 1 ( 1260 ) → π σ ( f 0 ( 500 ) ) decay width from the perspective that the $$a_1(1260)$$ a 1 ( 1260 ) resonance is dynamically generated from the pseudoscalar–vector interaction and the $$\sigma $$ σ arises from the pseudoscalar–pseudoscalar interaction. A triangle mechanism with $$a_1(1260) \rightarrow \rho \pi $$ a 1 ( 1260 ) → ρ π followed by $$\rho \rightarrow \pi \pi $$ ρ → π π and a fusion of two pions within the loop to produce the $$\sigma $$ σ provides the mechanism for this decay under these assumptions for the nature of the two resonances. We obtain widths of the order of 13–22 MeV. Present experimental results differ substantially from each other, suggesting that extra efforts should be devoted to the precise extraction of this important partial decay width, which should provide valuable information on the nature of the axial vector and scalar meson resonances and help clarify the role of the $$\pi \sigma $$ π σ channel in recent lattice QCD calculations of the $$a_1$$ a 1 .

Strong decays of the newly $$P_{cs}(4459)$$ as a strange hidden-charm $$\Xi _c{\bar{D}}^*$$ molecule

In our former work [arXiv:2011.07214], the $$P_{cs}(4459)$$ P cs ( 4459 ) observed by the LHCb Collaboration can be explained as a coupled strange hidden-charm $$\Xi _c{\bar{D}}^*/\Xi _c^*{\bar{D}}/\Xi _c'{\bar{D}}^*/\Xi _c^*{\bar{D}}^*$$ Ξ c D ¯ ∗ / Ξ c ∗ D ¯ / Ξ c ′ D ¯ ∗ / Ξ c ∗ D ¯ ∗ molecule with $$I(J^P)=0(3/2^-)$$ I ( J P ) = 0 ( 3 / 2 - ) . Here, we further discuss the two-body strong decay behaviors of the $$P_{cs}(4459)$$ P cs ( 4459 ) in the meson-baryon molecular scenario by input the former obtained bound solutions. Our results support the $$P_{cs}(4459)$$ P cs ( 4459 ) as the strange hidden-charm $$\Xi _c{\bar{D}}^*$$ Ξ c D ¯ ∗ molecule with $$I(J^P)=0(3/2^-)$$ I ( J P ) = 0 ( 3 / 2 - ) . The relative decay ratio between $$\Lambda _cD_s^*$$ Λ c D s ∗ and $$J/\psi \Lambda $$ J / ψ Λ is around 10, where the partial decay width for the $$\Lambda _cD_s^*$$ Λ c D s ∗ channel is around 0.6 to 2.0 MeV.

Strong decays of the $$\varXi (1620)^0$$ as a $$\varLambda {\bar{K}}$$ and $$\varSigma {\bar{K}}$$ molecule

In this work, we study the strong decays of the newly observed $$\varXi (1620)^0$$ Ξ ( 1620 ) 0 assuming that it is a meson-baryon molecular state of $$\varLambda {\bar{K}}$$ Λ K ¯ and $$\varSigma {\bar{K}}$$ Σ K ¯ . We consider four possible spin-parity assignments $$J^P=1/2^{\pm }$$ J P = 1 / 2 ± and $$3/2^{\pm }$$ 3 / 2 ± for the $$\varXi (1620)^0$$ Ξ ( 1620 ) 0 , and evaluate its partial decay width into $$\varXi \pi $$ Ξ π and $$\varXi \pi \pi $$ Ξ π π via hadronic loops with the help of effective Lagrangians. In comparison with the Belle data, the calculated decay width favors the spin-party assignment $$1/2^-$$ 1 / 2 - while the other spin-parity assignments do not yield a decay width consistent with data in the molecule picture. We find that about 52–68% of the total width comes from the $${\bar{K}}\varLambda $$ K ¯ Λ channel, while the rest is provided by the $${\bar{K}}\varSigma $$ K ¯ Σ channel. As a result, both channels are important in explaining the strong decay of the $$\varXi (1620)^0$$ Ξ ( 1620 ) 0 . In addition, the transition $$\varXi (1620)^0\rightarrow \pi \varXi $$ Ξ ( 1620 ) 0 → π Ξ is the main decay channel in the $$J^{P}=1/2^{-}$$ J P = 1 / 2 - case, which almost saturates the total width. These information are helpful to further understand the nature of the $$\varXi (1620)^0$$ Ξ ( 1620 ) 0 .

Comment on the X(3915) nonstandard hadron candidate

I review the experimental evidence for the X(3915), the candidate nonstandard meson associated with ωJ/ψ resonance-like peaks in B → KωJ/ψ and γγ → ωJ/ψ near M(ωJ/ψ) = 3920 MeV, and address the conjecture that it can be identified as the χ′c2, the radial excitation of the χc2 charmonium state. Since the partial decay width for B → KX(3915) is at least an order-of-magnitude higher than that for B → Kχc2, its assignment as the χ’c2 is dubious.

Searching for new physics in semi-leptonic baryon decays

We propose two different and complementary observables for singling out possible signals of physics beyond the Standard Model (SM) in the semi-leptonic decays [Formula: see text], both with the [Formula: see text] lepton and with a light lepton. The two observables are the partial decay width and a T-odd asymmetry, whose respective sensitivities to scalar and/or pseudo-scalar coupling are calculated as functions of the parameters characterizing new physics (NP). Two different form factors are used. Three particular cases are discussed and analyzed in detail.

MEASUREMENT OF THE TWO-PHOTON DECAY WIDTH OF THE INTERMEDIATE MASS HIGGS BOSONS IN A PHOTON-PHOTON COLLIDER

The feasibility of a measurement of the partial decay width of the intermediate-mass Higgs boson(MH=120 GeV ) into two photons at a photon-photon collider is studied by a simulation. It is found that the two-photon decay width can be measured with the statistical error of 7.6% with the integrated luminosity of 10fb-1. We also discussed a possibility toward further improvement with sophisticated b-quark tagging technique.