The LHCb Collaboration announced two pentaquark-like structures in the $J/\psi p$ invariant mass distribution. We show that the current information on the narrow structure at 4.45 GeV is compatible with kinematical effects of the rescattering from ${\chi }_{c1}p$ to $J/\psi p$: First, it is located exactly at the ${\chi }_{c1}p$ threshold. Second, the mass of the four-star well-established $\mathrm{\Lambda }(1890)$ is such that a leading Landau singularity from a triangle diagram can coincidentally appear at the ${\chi }_{c1}p$ threshold, and third, there is a narrow structure at the ${\chi }_{c1}p$ threshold but not at the ${\chi }_{c0}p$ and ${\chi }_{c2}p$ thresholds. In order to check whether that structure corresponds to a real exotic resonance, one can measure the process ${\mathrm{\Lambda }}_b^0\to K^{-}{\chi }_{c1}p$. If the $P_c(4450)$ structure exists in the ${\chi }_{c1}p$ invariant mass distribution as well, then the structure cannot be just a kinematical effect but is a real resonance; otherwise, one cannot conclude that $P_c(4450)$ is another exotic hadron. In addition, it is also worthwhile to measure the decay $\mathrm{\Upsilon }(1S)\to J/\psi p\overline{p}$: a narrow structure at 4.45 GeV but not at the ${\chi }_{c0}p$ and ${\chi }_{c2}p$ thresholds would exclude the possibility of a pure kinematical effect.

We calculate the $CP$-averaged branching ratios and $CP$-violating asymmetries of a number of two-body charmless hadronic decays ${\overline{B}}_s^0\to PP$, $PV$, $VV$ in the perturbative QCD (pQCD) approach to leading order in ${\alpha }_s$ (here $P$ and $V$ denote light pseudoscalar and vector mesons, respectively). The mixing-induced $CP$ violation parameters are also calculated for these decays. We also predict the polarization fractions of $B_s\to VV$ decays and find that the transverse polarizations are enhanced in some penguin-dominated decays such as ${\overline{B}}_s^0\to K^{*}{\overline{K}}^{*}$, $K^{*}\rho$. Some of the predictions worked out here can already be confronted with the recently available data from the CDF Collaboration on the branching ratios for the decays ${\overline{B}}_s^0\to K^{+}{\pi }^{-}$, ${\overline{B}}_s^0\to K^{+}{K}^{-}$ and the $CP$ asymmetry in the decay ${\overline{B}}_s^0\to K^{+}{\pi }^{-}$, and are found to be in agreement within the current errors. A large number of predictions for the branching ratios, $CP$ asymmetries, and vector-meson polarizations in ${\overline{B}}_s^0$ decays, presented in this paper and compared with the already existing results in other theoretical frameworks, will be put to stringent experimental tests in forthcoming experiments at Fermilab, CERN LHC, and Super $B$ factories.

In the covariant light-front quark model, we investigate the form factors of $B_c$ decays into $D$, $D^{*}$, $D_s$, $D_s^{*}$, ${\eta }_c$, $J/\psi$, $B$, $B^{*}$, $B_s$, and $B_s^{*}$ mesons. The form factors in the spacelike region are directly evaluated. To extrapolate the form factors to the physical region, we fit the form factors by adopting a suitable three-parameter form. At the maximally recoiling point, $b\to u$, $d$, and $s$ transition form factors are smaller than $b\to c$ and $c\to d$, $s$ form factors, while the $b\to u$, $d$, $s$, and $c$ form factors at the zero-recoiling point are close to each other. In the fitting procedure, we find that parameters in $A_2^{B_c{B}^{*}}$ and $A_2^{B_c{B}_s^{*}}$ strongly depend on decay constants of $B^{*}$ and $B_s^{*}$ mesons. Fortunately, semileptonic and nonleptonic $B_c$ decays are not sensitive to these two form factors. We also investigate branching fractions, polarizations of the semileptonic $B_c$ decays. $B_c\to ({\eta }_c,J/\psi )l\nu$ and $B_c\to (B_s,B_s^{*})l\nu$ decays have much larger branching fractions than $B_c\to (D,D^{*},B,B^{*})l\nu$. For the three kinds of $B_c\to Vl\nu$ decays, longitudinal contributions are comparable with the transverse contributions. These predictions will be tested on the ongoing and forthcoming hadron colliders.

Very recently, the LHCb collaboration has observed in the final state $$\Lambda _c^+ K^-\pi ^+\pi ^+$$Λc+K-π+π+ a resonant structure that is identified as the doubly charmed baryon $$\Xi _{cc}^{++}$$Ξ

Motivated by the recent LHCb observation of doubly charmed baryon $$\Xi _{cc}^{++}$$Ξcc++ in the $$\Lambda _c^+ K^-\pi ^+\pi ^+$$Λc+K-π+π+ final state, we analyze the weak decays of doubly heavy baryo