Showing papers by "Xiang Liu published in 2009"

X(3872) and Other Possible Heavy Molecular States

Abstract: We perform a systematic study of the possible molecular states composed of a pair of heavy mesons such as $D\bar{D}$ , $D^{\ast}\bar{D}$ , $D^{\ast}\bar{D}^{\ast}$ in the framework of the meson exchange model. The exchanged mesons include the pseudoscalar, scalar and vector mesons. Through our investigation, we find the following results. (1) The structure X(3764) is not a molecular state. (2) There exists strong attraction in the range r<1 fm for the $D^{*}\bar{D}^{*}$ system with J=0,1. If future experiments confirm Z +(4051) as a loosely bound molecular state, its quantum number is probably J P =0+. Its partner state Φ **0 may be searched for in the π 0 χ c1 channel. (3) Vector meson exchange provides strong attraction in the $D^{\ast}\bar{D}$ channel together with pion exchange. A bound state solution may exist with a reasonable cutoff parameter Λ∼1.4 GeV. X(3872) may be accommodated as a molecular state dynamically although drawing a very definite conclusion needs further investigation. (4) The $B^{\ast}\bar{B}$ molecular state may exist.

Y ( 4143 ) is probably a molecular partner of Y ( 3930 )

Abstract: After discussing the various possible interpretations of the $Y(4143)$ signal observed by the CDF collaboration in the $J/\ensuremath{\psi}\ensuremath{\phi}$ mode, we tend to conclude that $Y(4143)$ is probably a ${D}_{s}^{*}{\overline{D}}_{s}^{*}$ molecular state with ${J}^{PC}={0}^{++}$ or ${2}^{++}$ while $Y(3930)$ is its ${D}^{*}{\overline{D}}^{*}$ molecular partner as predicted in our previous work [X. Liu, Z. G. Luo, Y. R. Liu, and Shi-Lin Zhu, Eur. Phys. J. C 61, 411 (2009)]. Both the hidden-charm and open-charm two-body decays occur through the rescattering of the vector components within the molecular states while the three- and four-body open-charm decay modes are forbidden kinematically. Hence, their widths are narrow naturally. CDF, BABAR and Belle collaborations may have discovered heavy molecular states already. We urge experimentalists to measure their quantum numbers and explore their radiative decay modes in the future.

Newly observed D(sJ)(3040) and the radial excitations of P-wave charmed-strange mesons

Abstract: Inspired by the newly observed D{sub sJ}(3040){sup +} state, in this work we systemically study the two-body strong decays of P-wave charmed-strange mesons with the first radial excitation. Under the assignment of 1{sup +}(j{sup P}=(1/2){sup +}), i.e. the first radial excitation of D{sub s1}(2460){sup +}, we find that the width of D{sub sJ}(3040){sup +} is close to the lower limit of the BABAR measurement. This indicates that it is reasonable to interpret D{sub sJ}(3040){sup +} as the first radial excitation of D{sub s1}(2460){sup +}. Our calculation further predicts that 0{sup -}+1{sup -} channels, e.g., D{sup +}K*{sup 0}, D{sup 0}K*{sup +}, and D{sub s}{sup +}{phi}, are important for the search for D{sub sJ}(3040){sup +}. To help future experiments find the remaining three P-wave charmed-strange mesons with the first radial excitation, we present the predictions for the strong decays of these three P-wave charmed-strange mesons.

B(s1)(5830) and B*(s2)(5840)

Abstract: In this paper we investigate the strong decays of the two newly observed bottom-strange mesons ${B}_{s1}(5830)$ and ${B}_{s2}^{*}(5840)$ in the framework of the quark pair creation model. The two-body strong decay widths of ${B}_{s1}(5830{)}^{0}\ensuremath{\rightarrow}{B}^{*+}{K}^{\ensuremath{-}}$ and ${B}_{s2}^{*}(5840{)}^{0}\ensuremath{\rightarrow}{B}^{+}{K}^{\ensuremath{-}}$, ${B}^{*+}{K}^{\ensuremath{-}}$ are calculated by considering ${B}_{s1}(5830)$ to be a mixture between $|^{1}P_{1}⟩$ and $|^{3}P_{1}⟩$ states, and ${B}_{s2}^{*}(5840)$ to be a $|^{3}P_{2}⟩$ state. The double pion decay of ${B}_{s1}(5830)$ and ${B}_{s2}^{*}(5840)$ is supposed to occur via the intermediate state $\ensuremath{\sigma}$ and ${f}_{0}(980)$. Although the double pion decay widths of ${B}_{s1}(5830)$ and ${B}_{s2}^{*}(5840)$ are smaller than the two-body strong decay widths of ${B}_{s1}(5830)$ and ${B}_{s2}^{*}(5840)$, one suggests future experiments to search the double pion decays of ${B}_{s1}(5830)$ and ${B}_{s2}^{*}(5840)$ due to their sizable decay widths.

Light pseudoscalar meson and heavy meson scattering lengths

Abstract: We have performed a systematical calculation of the pion ($\ensuremath{\pi}$, $K$, $\ensuremath{\eta}$) and heavy pseudoscalar meson $S$-wave scattering lengths up to $\mathcal{O}({p}^{3})$ in the chiral perturbation theory in the heavy quark symmetry limit. With the three scattering lengths from the lattice simulations as input we estimate the unknown low-energy constants. Then we predict all the other unmeasured scattering lengths. The analytical expressions and predictions may be helpful to future investigations. Especially we note that the $DK$ scattering length is positive. Therefore their interaction is attractive, which helps to lower the mass of the bare charm-strange scalar state in the quark model through the couple-channel effect.

Bs1(5830)andBs2*(5840)

Abstract: In this paper we investigate the strong decays of the two newly observed bottom-strange mesons ${B}_{s1}(5830)$ and ${B}_{s2}^{*}(5840)$ in the framework of the quark pair creation model The two-body strong decay widths of ${B}_{s1}(5830{)}^{0}\ensuremath{\rightarrow}{B}^{*+}{K}^{\ensuremath{-}}$ and ${B}_{s2}^{*}(5840{)}^{0}\ensuremath{\rightarrow}{B}^{+}{K}^{\ensuremath{-}}$, ${B}^{*+}{K}^{\ensuremath{-}}$ are calculated by considering ${B}_{s1}(5830)$ to be a mixture between $|^{1}P_{1}⟩$ and $|^{3}P_{1}⟩$ states, and ${B}_{s2}^{*}(5840)$ to be a $|^{3}P_{2}⟩$ state The double pion decay of ${B}_{s1}(5830)$ and ${B}_{s2}^{*}(5840)$ is supposed to occur via the intermediate state $\ensuremath{\sigma}$ and ${f}_{0}(980)$ Although the double pion decay widths of ${B}_{s1}(5830)$ and ${B}_{s2}^{*}(5840)$ are smaller than the two-body strong decay widths of ${B}_{s1}(5830)$ and ${B}_{s2}^{*}(5840)$, one suggests future experiments to search the double pion decays of ${B}_{s1}(5830)$ and ${B}_{s2}^{*}(5840)$ due to their sizable decay widths

Line shape of the radiative open-charm decay of Y(4140) and Y(3930)

Abstract: In this work, we study the radiative open-charm decays $Y(4140)\ensuremath{\rightarrow}{D}_{s}^{*+}{D}_{s}^{\ensuremath{-}}\ensuremath{\gamma}$ and $Y(3930)\ensuremath{\rightarrow}{D}^{*+}{D}^{\ensuremath{-}}\ensuremath{\gamma}$ under the assignments of ${D}_{s}^{*}{\overline{D}}_{s}^{*}$ and ${D}^{*}{\overline{D}}^{*}$ as molecular states for $Y(4140)$ and $Y(3930)$, respectively. Based on our numerical result, we propose the experimental measurement of the photon spectrum of $Y(4140)\ensuremath{\rightarrow}{D}_{s}^{*+}{D}_{s}^{\ensuremath{-}}\ensuremath{\gamma}$, ${D}_{s}^{+}{D}_{s}^{*\ensuremath{-}}\ensuremath{\gamma}$ and $Y(3930)\ensuremath{\rightarrow}{D}^{*0}{\overline{D}}^{0}\ensuremath{\gamma}$, ${D}^{0}{\overline{D}}^{*0}\ensuremath{\gamma}$, ${D}^{*+}{D}^{\ensuremath{-}}\ensuremath{\gamma}$, ${D}^{+}{D}^{*\ensuremath{-}}\ensuremath{\gamma}$ can further test the molecular assignment for $Y(4140)$ and $Y(3930)$.

Contribution of final-state interaction to the branching ratio of B→ J/ ψ D

Abstract: To test the validity of perturbative QCD (pQCD) and investigate its range of application, one should look for a suitable process. B→J/ψD is a promising candidate. The linear momentum of the products is relatively small, so that there may exist a region where exchanged gluons are soft and the perturbative treatment may fail, so that the non-perturbative effect would be significant. We attribute such non-perturbative QCD effects to the long-distance final-state interaction (FSI) which is estimated in this work. We find that the contribution from the FSI to the branching ratio is indeed sizable and may span the rather wide range of 10−6∼10−5 and cover a region where the pQCD prediction is of the same order. A more accurate measurement of its branching ratio may provide important information about the application region of pQCD and help to clarify the picture of inelastic rescattering (i.e. FSI), which is generally believed to play an important role in B decays.

Discovery potential for charmoniumlike state Y(3940) by the meson photoproduction

Abstract: In this work, we investigate the discovery potential for $Y(3940)$ by the photoproduction process $\ensuremath{\gamma}p\ensuremath{\rightarrow}Y(3940)p$ The numerical result shows that the upper (lower) limit of the total cross section for $\ensuremath{\gamma}p\ensuremath{\rightarrow}Y(3940)p$ is up to the order of 1 nb ($01\text{ }\text{ }\ensuremath{\mu}\mathrm{b}$) Additionally, the background analysis and the Dalitz plot relevant to the production of $Y(3940)$ are studied The Dalitz plot analysis of $Y(3940)$ production indicates that the $Y(3940)$ signal can be distinguished from the background clearly The lower limit of the number of events of $Y(3940)$ reaches up to $10/002\text{ }\text{ }{\mathrm{GeV}}^{2}$ for $1\ifmmode\times\else\texttimes\fi{}{10}^{9}$ collisions of $\ensuremath{\gamma}p$ by studying the invariant mass spectrum of $J/\ensuremath{\psi}\ensuremath{\omega}$ An experimental search for $Y(3940)$ by the meson photoproduction is suggested

Charm physics —— A field full of challenges and opportunities

Abstract: In this review, we discuss some interesting issues in charm physics, which is full of puzzles and challenges. So far in this field, there exist many problems which have not obtained satisfactory answers yet as more unexpected phenomena Continue to be observed at the current facilities of high energy physics. Charm physics may become an ideal place for searching new resonances and studying non-perturbative QCD effects, moreover it is probably an area for exploring new physics beyond the Standard Model. More data will be available at the BE-SIII, B-factories, LHC and even the future ILC, which may open a wide window to a better understanding of its nature.

Semileptonic decays of Bs1, Bs2*, Bs0 and Bs1′

Abstract: Stimulated by recent observations of the excited bottom–strange mesons Bs1 and Bs2*, we calculate the semileptonic decays \(B_{s0},\,B_{s1}^{\prime},\,B_{s1},\,B_{s2}^{*}\to [D_{s}(1968),\linebreak D_{s}^{*}(2112),\,D_{sJ}(2317),\,D_{sJ}(2460)]\ell\bar{ u}\) , which is relevant for the exploration of the potential of searching these semileptonic decays in experiment.

Semileptonic decays of B s1 , B { /s2 * }, B s0 and B s1 '

Abstract: Stimulated by recent observations of the excited bottom–strange mesons B s1 and B 2 * , we calculate the semileptonic decays $B_{s0},\,B_{s1}^{\prime},\,B_{s1},\,B_{s2}^{*}\to [D_{s}(1968),\linebreak D_{s}^{*}(2112),\,D_{sJ}(2317),\,D_{sJ}(2460)]\ell\bar{ u}$ , which is relevant for the exploration of the potential of searching these semileptonic decays in experiment.