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Register a new userAnalysis of the $X(3842)$ as a D-wave charmonium meson
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In this article, we assign the newly reported state $X(3842)$ to be a D-wave $overline{c}c$ meson, and study its mass and decay constant with the QCD sum rules by considering the contributions of the vacuum condensates up to dimension-6 in the operator product expansion. The predicted mass $M_{X(3842)}=(3.844^{+0.0675}_{-0.0823}pm0.020)GeV$ is in agreement well with the experimental data $M_{X(3842)}=(3842.71pm0.16pm0.12)MeV$ from the LHCb collaboration. This result supports assigning $X(3842)$ to be a $1^{3}D_{3}$ charmonium meson. As the $1^{3}D_{3}$ $overline{c}c$ meson, its predicted strong decay width with the $^{3}P_{0}$ decay model is compatible with the experimental data.
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We study the semileptonic decays of $B_c$ meson to S-wave charmonium states in the framework of relativistic independent quark model based on an average flavor-independent confining potential $U(r)$ in the scalar-vector harmonic form $U(r)=frac{1}{2}(1+gamma^0)(ar^2+V_0)$, where ($a$, $V_0$) are the potential parameters.The form factors for $B_c^+to eta_c /psi e^+ u_e$ transitions are studied in the physical kinematic range. Our predicted branching ratios (BR) for transitions to ground state charmonia are found comparatively large $sim $ $10^{-2}$, compared to those for transitions to radially excited 2S and 3S states. Like all other mpdel predictions, our predicted BR are obtained in the hierarchy: BR($B_c^+to eta_c /psi (3S)$) $<$ BR($B_c^+to eta_c/ psi (2S)$) $<$ BR($B_c^+to eta_c /psi (1S)$). The longitudinal ($Gamma_L$) and transverse polarization ($Gamma_T$) for $B_c to psi(ns)$ decay modes are predicted in the small and large $q^2$ - region as well as in the whole physical region. The ratios for such transitions are obtained $frac {Gamma_L}{Gamma_T} < 1$ throughout the kinematic range which means the $B_c^+$ meson transitions to vector meson charmonium states take place predominantly in transverse polarization mode. The theoretical predictions on these transitions could be tested in the on-going and forthcoming experiments at LHCb.
A precision measurement of the mass difference between the $D^0$ and $D^{*0}$ mesons has been made using 316~pb$^{-1}$ of $e^{+}e^{-}$ annihilation data taken at $sqrt{s}=4170$~MeV using the CLEO-c detector. We obtain $Delta M equiv M(D^{*0})-M(D^0) =142.007pm0.015$(stat)~$pm$~0.014(syst)~MeV, as the average for the two decays, $D^0to K^-pi^+$ and $D^0to K^-pi^+pi^-pi^+$. The new measurement of $Delta M$ leads to $M(D^{*0})=2006.850pm0.049$~MeV, and the currently most precise measurement of the binding energy of the ``exotic meson X(3872) if interpreted as a $D^0D^{*0}$ hadronic molecule, $E_{b}(text{X}(3872))equiv M(D^0D^{*0})-M(text{X}(3872))=3pm192$ keV.
In this paper, we calculate the next-to-leading order (NLO) quantum chromodynamics (QCD) corrections to the exclusive processes $B_c^+to chi_{cJ}(h_c)pi^+$ in the framework of the nonrelativistic QCD (NRQCD) factorization formalism. The results show that NLO QCD corrections markedly enhance the branching ratios with $K$ factors of about 2.5. In combination with the study of $B_c^+to J/psipi^+$, we find that the NLO NRQCD prediction for the ratio of branching fractions $frac{mathcal{B}(B_c^+to chi_{c0}pi^+)}{mathcal{B}(B_c^+to J/psi pi^+)}$ is then compatible with the experimental measurement.
We report on some ideas concerning the nature of the X(3872) resonance and the need for approximately equal charged and neutral components of $D bar{D}^* +cc$. Then we discuss how some hidden charm states are obtained from the interaction between vector mesons with charm and can be associated to some of the charmonium-like X,Y,Z states. Finally we discuss how the nature of these states could be investigated through different types of radiative decay.
In this work, we calculate the amplitudes of the processes $cbar c({^3P_J}) rightarrow DD,DD^*, D^*D^* rightarrow cbar c({^3P_J})$ in the leading order of the nonrelativistic expansion. The imaginary parts of the amplitudes are corresponding to the branch decay widthes of the charmonium $cbar c({^3P_J}) rightarrow DD,DD^*, D^*D^*$ and the real parts are corresponding to the mass shifts of the charmonium $cbar c({^3P_J})$ due to these decay channels. After absorbing the polynomial contributions which are pure real and include the UV divergences, the ratios between the branch decay widthes and the corresponding mass shifts are only dependent on the center-of-mass energy. We find the decay widthes and the mass shifts of the $^3P_2$ states are exact zero in the leading order. The ratios between the branch decay widthes and the mass shifts for the $^3P_0, {^3P_1}$ states are larger than 5 when the center-of-mass energy is above the $DD,DD^*, D^*D^*$ threshold. The dependence of the mass shifts on the center-of-mass energy is nontrivial especially when the center-of-mass energy is below the threshold. The analytic results can be extended to the $b$ quark sector directly.
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