We report on a robust prediction of heavy $K^*$ meson by solving the Faddeev equations with fixed-center approximation for the three-body $KD\bar{D}^*$ system. As the excited Kaon state, $K^*$ is an exotic hidden charm meson with $M-iΓ/2=4307\pm2-i9\pm2$ MeV and $I(J^P)=1/2(1^-)$. We further performed the evaluation of the decay width of $K^*(4307)$ to the open two-body channels. We expect that the above findings inspire an experimental investigation of this exotic $K^*$ meson and to study the so far unexplored heavy strange meson sector.
In this article, we study the mass spectrum of the scalar hidden charm and hidden bottom tetraquark states which consist of the axial-axial type and the vector-vector type diquark pairs with the QCD sum rules.
Two-body nonleptonic decays of charmed mesons are studied on the basis of a simple pole-dominance model involving the vector, pseudoscalar and axial-vector meson poles.
Two body nonleptonic weak decays of bottom mesons to a pseudoscalar meson and an axial-vector meson involving charmed states are studied using the non-relativistic quark model. We calculate the branching ratios of these decays by employing the factorization hypothesis. Obtained results are in good agreement with the existing experimental data. We also calculated the branching ratios in the light of heavy quark symmetry constraints and compared with the exiting theoretical analyses.
The chiral SU(3) Lagrangian with pseudoscalar and vector $D$ mesons and with the octet and decuplet baryons is considered. The leading two-body counter terms involving two baryon fields and two $D$ meson fields are constructed in the open-charm sector. There are 26 terms. A combined expansion in the inverse of the charm quark mass and in the inverse of the number of colors provides sum rules that reduce the number of free parameter down to 5 only. Our result shows the feasibility of a systematic computation of the open-charm baryon spectrum based on coupled-channel dynamics.
In this talk, we show our recent theoretical results for three-body systems in the charm sector which are made of three hadrons and contain one nucleon, one $D$ meson and in addition another meson, $\bar{D}$, $K$ or $\bar{K}$.
Studying the hidden-charm dipion decays of the charmoniumlike state Y(4360), we show that there exist charged charmoniumlike structures near $D\bar{D}^*$ and $D^*\bar{D}^*$ thresholds in the $J/ψπ^+$, $ψ(2S)π^+$ and $h_c(1P)π^+$ invariant mass spectra of the corresponding hidden-charm dipion decays of Y(4360) using the {\it{Initial Single Pion Emission} mechanism}. We suggest to do further experimental study on these predicted charged enhancement structures, especially by BESIII, Belle, and the forthcoming BelleII.
We present the formalism for the decay of dynamically generated scalar mesons with open- or hidden-charm and give results for the decay of D^*_{s0} (2317) to γD_s^* plus that of a hidden charm scalar meson state predicted by the theory around 3700 MeV decaying into γJ/ψ.
Using a constituent quark model we study the mass and decay channels of meson meson and meson baryon structures in the charm sector. We show that the $X(3872)$ and $X(3940)$ resonances can be described as mixed charmonium-molecular states with $J^{PC}=1^{++}$, whereas the $X(3915)$ and the $Y(3940)$ can be assigned to similar mixed states with $J^{PC}=0^{++}$. In the baryon spectrum we identify the $Λ^+_c(2940)$ as a $D^*N$ molecule with $(I)J^P=(0)3/2^-$ and the recently reported $X_c(3250)$ as a $D^*Δ$ resonance with $(I)J^P=(1)5/2^-$ or $(I)J^P=(2)3/2^-$.
Within the framework of heavy quark effective theory and chiral perturbation theory, masses and splittings of heavy charm mesons are studied. A mass formula is used for comprehensive analysis of low lying charm meson states.The variation of mass splittings and spin splittings with respect to various symmetry conserving and symmetry breaking parameters have also been focussed.
In this article, we perform a systematic study of the mass spectrum of the vector hidden charmed and bottomed tetraquark states using the QCD sum rules.
We present a $U(4)_R \times U(4)_L$ chirally symmetric model, which in addition to scalar and pseudoscalar mesons also includes vector and axial-vector mesons. A part from the three new parameters pertaining to the charm degree of freedom, the parameters of the model are fixed from the $N_f=3$ flavor sector. We calculate open charmed meson masses and the weak decay constants of nonstrange open charm $D$ and strange open charm $D_S$. We also evaluate the (OZI-dominant) strong decays of open charmed mesons. The results are turn out to be in quantitative agreement with experimental data.
An update is given of the determination of leptonic decay constants of charm and beauty mesons in the framework of relativistic Hilbert moments and Laplace transform QCD sum rules.
An outstanding mystery of charmonium physics is why the J/ψdecays prominently to pseudoscalar plus vector meson channels, such as J/ψ-> ρπand J/ψ-> K^*K, whereas the ψ'(2S) does not. We show that such decays of J/ψand their suppression for ψ'(2S) follow naturally from the existence of intrinsic charm |qbar q cbar c> Fock components of the light vector mesons.
Fragmentation functions for heavy-light mesons, like the charmed D, D^* mesons, are proposed. They rest on next-to-leading QCD Perturbative Fragmentation Functions for heavy quarks, with the addition of a non-perturbative term describing phenomenologically the quark --> meson transition. The cross section for production of large p_T D, D^* mesons at the Tevatron is evaluated in this framework.
The hadroproduction of charmed mesons is discussed within the framework of the modified Quark-Gluon String model (QGSM) taking into account the decays of corresponding $S$--wave resonances like $D^*$. It is shown that the estimate of the $c\bar{c}$--pair contribution to the quark sea of colliding hadrons strongly depends on the parametrization of the function of the leading light quark fragmentation into charmed mesons. A description of the existing experimental data on inclusive spectra and asymmetries of leading and nonleading $D$ - and $D^*$ - meson production in $ πp$ -, $p p$ - and $Σp$ -…
Masses of open- and hidden-charm tetra-quark scalar mesons are studied in a new approach. As the result, newly estimated masses of hidden-charm sector are significantly lower than our earier ones by a naive quark counting. In particular, our new result on the non-strange iso-triplet scalar mesons should be compared with the experiment that an indication of tiny eta pi peak around 3.2 GeV has been observed, while no signal in the eta_c pi channel.
The possibility of using charm meson physics to test the Standard Model (SM) is reviewed. In the case of $D^0-\bar{D}^0$ mixing, the SM contributions are carefully considered and the existence of a window for the observation of new physics is discussed. Some examples of extensions of the SM giving large mixing signals are presented. Finally, some distinctive aspects of CP violation and rare decays in charm mesons are discussed.
The masses of the excited heavy tetraquarks with hidden charm are calculated within the relativistic diquark-antidiquark picture. The dynamics of the light quark in a heavy-light diquark is treated completely relativistically. The diquark structure is taken into account by calculating the diquark-gluon form factor. New experimental data on charmonium-like states above open charm threshold are discussed. The obtained results indicate that X(3872), Y(4260), Y(4360), Z(4248), Z(4433) and Y(4660) could be tetraquark states with hidden charm.
Predictions of two channels in the three-bod decays of the charmed mesons are made within the heavy hadron chiral perturbation theory. There still exists the problem that the theoretical expectation is too small compared to the experimental data.
It is suggested that the recently observed enhancement of the relative yield in $e^+e^-$ annihilation of states with hidden charm and hidden strangeness above 4.43\,GeV is associated with the $S$ wave production of the charmed strange meson pairs $D_{s0}(2317) \bar D_s^* + {\rm c.c.}$ and $D_{s1}^*(2460) \bar D_s+ {\rm c.c.}$. This mechanism implies a pattern of breaking of the Heavy Quark Spin Symmetry (HQSS) that can be tested in the final channels such as $η_c(1S) ϕ$, $h_c(1P) η$, $h_c(1P) η' $ produced in the same energy range.
We present here recent results on the investigations of the mass spectrum (S-states and P-states), decay constants, decay widths and life time of the D, $D_s$,and $B_c$mesons within the framework of phenomenological potential models.We also present the binding energy and the masses of the di-meson molecular systems with one or more charm meson combinations. Many of the newly found experimental open charm states are identified with the orbital excitations of the conventional open charm mesons while others like X(3872), Y(3930), $D_{sJ}$(2632, 2700) \emph{etc.}, are identified as molecular like …
In this paper, we calculate the strong decays of $2^+$ heavy-light states, namely, the charmed $D^*_2(2460)^0$ meson and the charm-strange $D^*_{s2}(2573)^+$ meson. The method we adopt is the reduction formula, PCAC relation and low energy theorem, following which, the transition amplitudes are calculated. The wave functions of the heavy mesons involved are achieved by solving the instantaneous Bethe-Salpeter equation. As the OZI-allowed two-body strong decays give the dominant contribution, they can be used to estimate to total widths of mesons. Our results are: $Γ[D^*_2(2460)^0]=51.3$ MeV an…
In this study, the properties of the $J^{PC}=1^{++}$ hidden charm poles are analyzed under the variation of the bare 2P charmonium mass within the effective field theory proposed in Ref.[1]. The main focus of the current work is on the pole trajectory of the $χ_{c1}(2P)$ charmonium dressed by the $D \bar{D}^*$ meson loops. It is shown that the trajectories of the pole change radically for values of the bare charmonium mass above a certain value and also depending on how close the pole is to the threshold.
We investigate the masses of the pseudoscalar ($D$($D^0$, $D^+$), $\bar{D}$($\bar{D^0}$, $D^-$) and vector open charm mesons ($D^*$($D^{*0}$, $D^{*+}$), ${\bar{D}}^*$(${\bar{D}}^{*0}$, $D^{*-}$) as well as the pseudoscalar ($η_c(1S)$, $η_c(2S)$) and the vector charmonium states ($J/ψ$, $ψ(2S)$, $ψ(1D)$) in the asymmetric hot strange hadronic medium in the presence of strong magnetic fields. In the magnetized medium, the mass modification of open charm mesons due to their interactions with baryons and the scalar fields ($σ$, $ζ$, and $δ$) are investigated in a chiral effective model. Moreover, …
Non-strange and strange pentaquaks with hidden charm are considered as diquark-diquark-antiquark composite systems. Spin and isospin content of such exotic states is discussed and masses are evaluated.
The relativistic four-quark equations are found in the framework of coupled-channel formalism. The dynamical mixing of the meson-meson states with the four-quark states is considered. The four-quark amplitudes of the tetraquarks with hidden charm including u, d, s and charmed quarks are constructed. The poles of these amplitudes determine the masses and widths of tetraquarks.
In this presentation I explain our framework for dynamically generating resonances from the meson meson interaction. Our model generates many poles in the T-matrix which are associated with known states, while at the same time new states are predicted.
Using the experimental data on pentaquarks with a hidden charm, new upper limits on the intrinsic charm in the proton are obtained, possible shapes of heavy quark distributions inside the proton are discussed.
We compare the predictions of the collinear parton model and the k_T-factorization approach in JΨand D^\star meson photoproduction at HERA energies. It is shown that obtained in the both approaches D^\star meson spectra over p_T and ηas well as JΨmeson p_T- and z-spectra are very different. The predictions obtained in the k_T-factorization approach are agree with the experimental data well. We also predict the nontrivial p_T-dependence of the the spin parameter $α(p_T) in the JΨphotoproduction.
We have applied the Meson Cloud Model (MCM) to calculate the charm and strange antiquark distribution in the nucleon. The resulting distribution, in the case of charm, is very similar to the intrinsic charm momentum distribution in the nucleon. This seems to corroborate the hypothesis that the intrinsic charm is in the cloud and, at the same time, explains why other calculations with the MCM involving strange quark distributions fail in reproducing the low x region data. From the intrinsic strange distribution in the nucleon we have extracted the strangeness radius of the nucleon, which is in …
We enlarge the so-called extended linear Sigma model (eLSM) by including the charm quark according to the global $U(4)_r\times U(4)_l$ chiral symmetry. In the eLSM, besides scalar and pseudoscalar mesons, also vector and axial-vector mesons are present. Almost all the parameters of the model were fixed in a previous study of mesons below 2 GeV. In the extension to the four-flavor case, only three additional parameters (all of them related to the bare mass of the charm quark) appear. We compute the (OZI-dominant) strong decays of open charmed mesons. The results are compatible with the experime…
In the wake of recent measurements of ratios of semileptonic branching fractions: ${\cal R}_{J/ψ}, {\cal R}_D$ and ${\cal R}_{D^*}$ reported by the LHCb, BELLE and HFLAV Collaborations, we calculate invariant form factors for the exclusive semileptonic $B_c$-meson decays to radially excited charmonium and charm meson states in the full kinematical region within the framework of relativistic independent quark (RIQ)model. We evaluate the lepton mass effect in the decay processes induced by $b\to c,u$ transition at the quark level. Our predictions on branching fractions for $B_c\to η_c/ψ(nS)$ are…
We provide results for the open-flavor strong decays of open-charm ($D$ and $D_{\rm s}$) and open-bottom ($B$, $B_{\rm s}$ and $B_{\rm c}$) mesons. The decays are calculated in a modified version of the $^3P_0$ pair-creation model, assuming harmonic oscillator wave functions. The spectra of open-charm and open-bottom mesons used in the calculations are computed within Godfrey and Isgur's relativized quark model. Quantum number assignments are also provided. Our results are compared with the existing experimental data.
In this work we study the implications of light-quark pionic matter at finite temperatures on the properties of open and hidden charm mesons. The meson-meson interactions are described by means of a chiral unitary approach accounting for coupled channels effects. The in-medium Lippmann-Schwinger Equations, which consider the change in self-energy that the mesons acquire from interacting with the surrounding pionic matter, are solved self-consistently, and the spectral functions of the mesons in the hot pion bath are obtained. It is observed that the charmed mesons develop a quite substantial p…
We present a detailed investigation on the intrinsic charm content in a light meson within the 't Hooft model, namely, the two-dimensional QCD in large $N_c$ limit. The intrinsic charm parton distribution function (PDF) of a light meson, which first arises at order $N_c^{-1}$, is explicitly expressed in terms of the 't Hooft wave functions of the light meson and an infinite towers of excited charmed mesons. We also derive the functional forms from the two-dimensional counterparts of the meson cloud model (MCM) and Brodsky-Hoyer-Peterson-Sakai (BHPS) model. We then make a quantitative compariso…
We analyze charm meson semileptonic $D \to V l ν_l$ and $D\to P l ν_l$ and nonleptonic $D \to P V$, $D \to PP$ and $D \to VV$ decays within a model which combines the heavy quark effective Lagrangian and chiral perturbation theory.
I present a brief review of results obtained both in open and hidden charm spectroscopy, discussing the interpretation of $D_{sJ}(2860)$, $D_{sJ}(2700)$ and X(3872).
In the pole-dominance model for the two-body nonleptonic decays of charmed mesons $D \rightarrow PV$ and $D \rightarrow VV$, it is shown that the contributions of the intermediate pseudoscalar and the axial-vector meson poles cancel each other in the annihilation diagrams in the chiral limit. In the same limit, the annihilation diagrams for the $D \rightarrow PP$ decays vanish independently.
We discuss recent theoretical developments in the context of charmed exotics with special emphasis on hadronic molecules. Especially we discuss, how these could be identified from experimental as well as lattice QCD observables.
We present predictions for the inclusive production of charmed hadrons at the CERN LHC in the general-mass variable-flavor-number scheme at next-to-leading order. Detailed numerical results are compared to data where available, or presented in a way to ease future comparisons with experimental results. We also point out that measurements at large rapidity have the potential to pin down models of intrinsic charm.
If the recently-discovered charmonium state X(3870) is a loosely-bound molecule of the charm mesons D^0 and \bar D^{*0} or \bar D^0 and D^{*0}, it can be produced in e^+ e^- annihilation at the Υ(4S) resonance by the coalescence of charm mesons produced in the decays of B^+ and B^- mesons. Remarkably, in the case of 2-body decays of the B mesons, the leading contribution to the coalescence probability depends only on hadron masses and on the width and branching fractions of the B meson. As the binding energy E_b of the molecule goes to zero, the coalescence probability scales as E_b^{1/2} log(…
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.
The scattering cross sections of charm mesons with hadrons such as the pion, rho meson, and nucleon are studied in an effective Lagrangian. In heavy ion collisions, rescattering of produced charm mesons by hadrons affects the invariant mass spectra of both charm meson pairs and dileptons resulting from their decays. These effects are estimated for heavy ion collisions at SPS energies and are found to be significant.
We review some recent developments in charm meson physics. In particular, we discuss theoretical predictions and experimental measurements of charmed meson decays to leptonic, semileptonic, and hadronic final states and implications of such measurements to searches for new physics. We discuss D0-anti-D0-mixing and CP-violation in charm, and discuss future experimental prospects and theoretical challenges in this area.
We investigate the in-medium masses of open charm mesons ($D$($D^0$, $D^+$), $\bar{D}$($\bar{D^0}$, $D^-$), $D_s$(${D_{s}}^+$, ${D_{s}}^-$)) and charmonium states ($J/ψ$, $ψ(3686)$, $ψ(3770)$, $χ_{c0}$, $χ_{c2}$) in strongly magnetized isospin asymmetric strange hadronic matter using a chiral effective model. In the presence of the magnetic field, the number density and scalar density of charged baryons have contributions from Landau energy levels. The mass modifications of open charm mesons arise due to their interactions with nucleons, hyperons, and the scalar fields (the non-strange field $…
Theoretical predictions of cross sections and properties of the $J/ψ$-meson production in association with an open charm hadron and formation of two open charm hadrons from two $c\bar{c}$ pairs in the LHC conditions are presented. Processes in both single and in double parton scattering mechanisms are included into consideration. Special attention is paid to the kinematic limits of the LHCb detector for which comparison with the newest experimental data is carried out.
We study the so-called extended linear sigma model for the case of four quark flavors. This model is based on global chiral symmetry and dilatation invariance and includes, besides scalar and pseudoscalar mesons, vector and axial-vector mesons. Most of the parameters of the model have been determined in previous work by fitting properties of mesons with three quark flavors. Only three new parameters, all related to the current charm quark mass, appear when introducing charmed mesons. Surprisingly, within the accuracy expected from our approach, the masses of open charmed mesons turn out to be …
A way of circumventing the gauge and infrared problems with effective Wilson coefficients is shown. Implications of experimentally measured charmless $B$ decays are discussed.
Mixing and CP violation in charm meson decays provide a unique probe of possible physics beyond the standard model. In this paper, we give a brief review of the current measurements from the BABAR experiment.
In this paper, we perform a combined study of $2S$ and $1D$ open-charm mesons with natural spin-parity. Our results indicate that $D^*_1(2600)/D^*_{s1}(2700)$ and $D^*_1(2760)/D^*_{s1}(2860)$ are predominantly the $2^3S_1$ and $1^3D_1$ charmed/charmed-strange mesons, respectively, while $D_3^*(2760)/D_{s3}^*(2860)$ can be regarded as the $1^3D_3$ charmed/charmed-strange mesons. In addition, some typical ratios of partial widths of the discussed natural states are predicted, by which future experiments can test these assignments, especially for the $2S$-$1D$ mixing scheme existing in $D^*_1(260…
Chiral thermodynamics of charmed mesons is formulated at finite temperature within a $2+1+1$-flavored effective Lagrangian incorporating heavy quark symmetry. The charmed-meson mean fields act as an extra source which breaks the chiral symmetry explicitly. This leads to effective interactions between the light and heavy-light mesons, which intrinsically depend on temperature. Effective masses of the scalar and pseudoscalar charmed-mesons tend to approach each other as increasing temperature, so that the splitting between the chiral partners is reduced. These chiral splittings are shown to be l…
In this talk we summarize our latest results on the study of three-body systems with explicit/hidden charm and with strangeness. In particular, we focus on the $K D D $ and $K D\bar D^*$ systems, where a charm $+2$, isospin $1/2$ and strangeness $+1$ state is found with a mass around 4140 MeV in the former and a $K^*$ state, with hidden charm, at a mass around 4307 MeV is obtained in the latter. Both states are predictions of our model and the experimental confirmation of them would be important to understand the properties of the strong interaction in the presence of heavy quarks.
We determine the strong couplings of three mesons that involve, at least, one $η_c$ or $J/ψ$ meson, within the framework of a constituent-quark model by means of relativistic dispersion formulations. For strong couplings of $J/ψ$ mesons to two charmed mesons, our approach leads to predictions roughly twice as large as those arising from QCD sum rules.
