$D_{sJ}(2700)$ and other puzzling states in charm spectroscopy

Recent issues in open and hidden charm spectroscopy

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).

通过非淬火粲偶素谱学对$R$值数据的重新分析澄清$\psi(4160)$令人困惑的质量位移

Clarifying the puzzling mass shift of the $ψ(4160)$ via a reanalysis of $R$-value data with unquenched charmonium spectroscopy

通过非淬火粲偶素谱重新分析BESII R值数据，证明ψ(4160)质量无需上移，4.19 GeV增强源于邻近态相干，并给出64个等价解及其现象学评估。

Speculations in hadron spectroscopy

A selected survey is presented of the recent progress in hadron spectroscopy. This includes spin-singlet charmonium states, excitations of charmonium and open-charm mesons, double-charm baryons, and pentaquark candidates. Models proposing exotic bound states or resonances are reviewed. The sector of exotic mesons with two heavy quarks appears as particularly promising.

Puzzles in charm spectroscopy

We briefly analyze aspects of open and hidden charm resonances, discussing in particular the mesons $D_{sJ}(2860)$ and X(3872).

Spectroscopy of di-meson bound states in charm and beauty sector

Using the Woods Saxon plus Coulomb type of interaction between two hadron molecules, we have calculated the binding energies and masses of the tetraquark states such as $D\bar{D}$, $D\bar{D}^*$, $D^*\bar{D}^*$, $D^+\bar{D}^*$ in the charm sector and $B\bar{B}$, $B^*\bar{B}^*$, $B\bar{B}^*$ in the bottom sector.

New open and hidden charm spectroscopy

Many new results on open and hidden charm spectroscopy have been obtained recently. We present a short review of the experimental findings in the meson sector, of the theoretical interpretations and of the open problems, with a discussion on the possibility that some mesons are not quark-antiquark states.

Study of charmonium-like and fully-charm tetraquark spectroscopy

The masses of tetraquark states of all $qc\bar q \bar c$ and $cc\bar c \bar c$ quark configurations are evaluated in a constituent quark model, where the Cornell-like potential and one-gluon exchange spin-spin coupling are employed. All model parameters are predetermined by comparing the theoretical and experimental masses of light, charmed and bottom mesons. The theoretical predictions of the charmoniumlike tetraquarks are compared with the observed $XYZ$ states, and one tentative assignment is suggested. The work suggests that the $X(6900)$ observed by LHCb is likely to be the first radial e…

The charmonium and bottomonium mass spectroscopy with a simple approximaton of the kinetic term

In this paper we propose a particular description of meson spectroscopy, with emphasis in heavy bound states like charmonia and bottomonia, after working on the main aspects of the construction of an effective potential model. We use the prerogatives from ``soft QCD'' to determine the effective potential terms, establishing the asymptotic Coulomb term from one gluon exchange approximation. At the same time, a linear confinement term is introduced in agreement with QCD and phenomenological prescription. The main aspect of this work is the simplification in the calculation, consequence of a prec…

Spectroscopy of excited charmed mesons

We derive mass formulas for the $P$-wave orbitally excited $D^*_{0(s)}$, $D^\prime_{1(s)}$, $D_{1(s)}$, and $D^*_{2(s)}$ heavy charmed mesons including all effects from one-loop corrections that contribute at leading order in chiral expansion. In our formalism, the effects to first order in $m_q$, where $m_q$ is the light quark mass, and to first order in $m^{-1}_c$, where $m_c$ is the charm quark mass, and $m_q/m_c$ terms are considered. The experimental and lattice QCD results on the charmed meson spectra are employed to fix the large number of counterterms appearing in the effective chiral …

Mesons with Beauty and Charm: Spectroscopy

Applying knowledge of the interaction between heavy quarks derived from the study of $c\overline{c}$ and $b\overline{b}$ bound states, we calculate the spectrum of $c\overline{b}$ mesons. We compute transition rates for the electromagnetic and hadronic cascades that lead from excited states to the $^1\text{S}_0$ ground state, and briefly consider the prospects for experimental observation of the spectrum.

Mesons with Beauty and Charm: New Horizons in Spectroscopy

The $B_c ^+$ family of $(c\bar{b})$ mesons with beauty and charm is of special interest among heavy quarkonium systems. The $B_c ^+$ mesons are intermediate between $(c\bar{c})$ and $(b\bar{b})$ states both in mass and size, so many features of the $(c\bar{b})$ spectrum can be inferred from what we know of the charmonium and bottomonium systems. The unequal quark masses mean that the dynamics may be richer than a simple interpolation would imply, in part because the charmed quark moves faster in $B_c$ than in the $J/ψ$. Close examination of the $B_c ^+$ spectrum can test our understanding of t…

Heavy-light charm mesons spectroscopy and decay widths

We present the mass formula for heavy-light charm meson for one loop, using heavy quark effective theory. Formulating an effective Lagrangian, the masses of the ground state heavy mesons have been studied in the heavy quark limit including leading corrections from finite heavy quark masses and nonzero light quark masses using a constrained fit for the eight equation having eleven parameters including three coupling constants g, h and g'. Masses determined from this approach is fitted to the experimentally known decay widths to estimate the strong coupling constants, showing a better match with…

New Charm Spectroscopy: Insights from Theory

We discuss several new observations of mesons with open charm. In particular, we consider $D_{sJ}(2317)$ and $D_{sJ}(2460)$ and compare their isospin violating decays into $D^{(*)}_s π$ to the radiative decays analysed using light-cone QCD sum rules. The results support the interpretation of these two mesons as ordinary $c{\bar s}$ states. In the case of $D_{sJ}(2860)$ and $D_{sJ}(2710)$ we compute the strong decays in the heavy quark limit. Comparison of the results with recent measurements of the BaBar Collaboration leads to identify $D_{sJ}(2710)$ with the first radial excitation of $D_s^*$…

Spectroscopy of all charm tetraquark states

The mass spectra of all-charm tetraquark states with the [cc][$\bar{c}\bar{c}$] quark configuration are investigated. The coulomb plus linear potential is used in conjunction with the relativistic mass correction term $\mathcal{O}(\frac{1}{m})$. To determine the fitting parameters for all-charm tetraquarks states [cc][$\bar{c}\bar{c}$], we first calculate the mass spectra of charmonia [c$\bar{c}$] and its decay constants ($f^{2}_{P/V}$). We estimated the masses of the tetraquark states in their ground and radially excited states. For mass spectra of tetraquark states, we also included spin-spi…

Charmonium Spectroscopy from Lattice QCD

I give a short review of the current status of lattice QCD calculations of the spectrum of charmonium.

On the hidden charm state at 3872 MeV

We discuss some puzzling aspects of the narrow hidden charm resonance that was recently discovered by the Belle Collaboration at mass 3872 MeV. In order to determine its quantum numbers, a crucial piece of information is the spin of the dipion in the decay final state pi^+pi^-J/psi. We give the angular distributions and correlations of the final particles in the decay which will give this information about the nature of this resonance.

Spectroscopy of the All-Charm Tetraquark

We use a non-relativistic model to study the mass spectroscopy of a tetraquark composed by $c \, \bar{c} \, c \, \bar{c}$ quarks in the diquark-antidiquark picture. By numerically solving the Schrödinger equation with a Cornell-inspired potential, we separate the four-body problem into three two-body problems. Spin-dependent terms (spin-spin, spin-orbit and tensor) are used to describe the splitting structure of the $c\bar{c}$ spectrum and are also extended to the interaction between diquarks. Recent experimental data on charmonium states are used to fix the parameters of the model and a satis…

Hadron spectroscopy from strangeness to charm and beauty

Quarks of different flavors have different masses, which will cause breaking of flavor symmetries of QCD. Flavor symmetries and their breaking in hadron spectroscopy play important role for understanding the internal structures of hadrons. Hadron spectroscopy with strangeness reveals the importance of unquenched quark dynamics. Systematic study of hadron spectroscopy with strange, charm and beauty quarks would be very revealing and essential for understanding the internal structure of hadrons and its underlying quark dynamics.

Open charm hadron spectroscopy at B-factories

Open charm hadrons are excellent probe to study the dynamics of quarks and gluons inside hadrons. Because the mass of a charm quark is heavier than $Λ_{QCD}$, the so called heavy quark symmetry emerges in the hadron containing a charm quark and plays a central role in the classification and constraining the interactions. Belle and BaBar, which are B-factory experiments, have made significant advances in the field of open charm hadron spectroscopy in these 15 years. In this article, experimental advances on both open charm mesons and baryons by B-factory experiments are reviewed. Finally, the p…

Charmonium spectroscopy and mixing with light quark and open charm states from nF=2 lattice QCD

We study the charmonium spectrum including higher spin and gluonic excitations. We determine an upper limit on the mixing of the eta_c ground state with light pseudoscalar flavour-singlet mesons and investigate the mixing of charmonia near open charm thresholds with pairs of (excited) D and anti-D mesons. For charm and light valence quarks and nF=2 sea quarks, we employ the non-perturbatively improved Sheikholeslami-Wohlert (clover) action. Excited states are accessed using the variational technique, starting from a basis of suitably optimised operators. For some aspects of this study, the use…

从能谱和磁矩探测隐藏charm五夸克的自旋宇称结构

Probing the spin parity structure of hidden charm pentaquarks from spectroscopy and magnetic moments

通过能谱和磁矩研究隐藏charm五夸克的自旋宇称结构，利用重子介子分子框架确定其JP分配并验证磁矩作为量子数识别的可观测量。

Open charm meson spectroscopy: Where to place the latest piece of the puzzle

We discuss how to classify the $c{\bar s}$ meson $D_{sJ}(3040)$ recently discovered by the BaBar Collaboration. We consider four possible assignments, together with signatures useful to distinguish among them.

重味系统中的奇特强子谱学

Exotic Hadron Spectroscopy in Heavy-Flavor Systems

本文综述了重味强子谱学中发现的各类奇特强子态，包括隐藏粲五夸克态、带电类粲偶素结构、重夸克偶素-重夸克偶素系统中的共振态、双重重四夸克态和开味四夸克态，并讨论了这些态的系统性特征。

Excited spectroscopy of mesons containing charm quarks from lattice QCD

We present highly excited spectra of charmonium, charm-light and charm-strange mesons using the dynamical anisotropic lattices of the Hadron Spectrum Collaboration. The use of novel techniques has allowed us to extract these spectra with a high degree of statistical precision, while also enabling us to observe states as high as spin-4, states with exotic quantum numbers and candidate gluonic excitations. We discuss the phenomenology of these spectra, and also present preliminary results of Dπ scattering considering only the lowest partial wave in the isospin-3/2 channel.

Charm physics: theoretical review

We review recent developments in charm physics, focusing on the physics of charmed mesons. We discuss charm spectroscopy, decay constants, as well as searches for new physics with charmed mesons. We discuss D0-anti-D0 mixing and CP-violation in charm decays. We also present the modified Nelson plot of charm mixing predictions.

Charmonium Physics at a Tau-Charm Factory

This talk summarizes the status of the charmonium system, with particular emphasis on outstanding problems in QCD spectroscopy which a tau-charm factory can address.

Charmed meson spectroscopy on the lattice

We present a calculation of the spectrum of low-lying D and D_s mesons calculated on 2+1 flavor configurations with Clover-Wilson quarks generated by the PACS-CS collaboration. S- and P-wave states are explored for pion masses down to 156MeV, including some excited states. As a benchmark, a calculation of the low-lying charmonium spectrum is performed. While the charmonium results agree favorably with experiment, noticeable differences remain for charmed mesons in channels where resonances close to multi-particle thresholds exist.

A Cicerone for the physics of charm, Part I: production, spectroscopy, lifetimes

This is part I of a two-part review of charm physics. After briefly recapitulating the history of the charm quantum number we sketch the experimental environments and instruments employed to study the behaviour of charm hadrons and then describe the theoretical tools for treating charm dynamics. After discussing a wide range of inclusive production processes we analyze the spectroscopy of hadrons with hidden and open charm and the weak lifetimes of charm mesons and baryons. In part II we shall address exclusive charm decays, $D^0 - \bar D^0$ oscillations and CP violation. This review is meant …

类粲素介子、含粲重轻介子、AdS/QCD 与构型熵的光谱学

Spectroscopy of charmonium-like mesons, heavy-light mesons with charm, AdS/QCD, and configurational entropy

本文利用四味 AdS/QCD 模型结合构型熵，研究四类粲介子族，预测未探索重粲介子共振态质量谱并识别 PDG 中的新态。

Perspectives on Tau-Charm Factory Physics

The Tau-Charm Factory combines the optimum conditions to perform a high-precision investigation of the $τ$ and $ν_τ$ leptons, the $c$ quark, and light-quark, glueball and hybrid spectroscopy. An overview of the broad physics program that this facility will address is presented.

Spectroscopy of Doubly-Charmed Baryons in Lattice QCD

We present results for masses of spin-1/2 and spin-3/2 double-charm baryons in quenched lattice QCD, from an exploratory study using a non-perturbatively improved clover action at beta=6.2. We have studied local operators and we observe, after appropriate projections, a good signal for the ground states. We also present results for single-charmed baryons and spin-splittings for both double- and single-charmed states.

稀有粲衰变中的级联拓扑及其对CP破坏的启示

Cascade topologies in rare charm decays and implications for CP violation

针对粲介子强子衰变中CP破坏的理论计算不足问题，研究了$D^0\to a_1(1260)^+(\to ρ(770)^0π^+)\\,π^-$级联拓扑对稀有衰变分支比及$D^0\toπ^+π^-$衰变CP不对称性的潜在贡献。

Double Charm Physics

We review the weak-decay and spectroscopy properties of baryons with two charmed quarks. We also present the convergent speculations on exotic mesons $(QQ\bar{q}\bar{q})$ with two heavy quarks and two light antiquarks.

(A Few) Recent Developments in Hadron Spectroscopy

Recent years have seen rapid developments in our knowledge and understanding of meson spectroscopy, especially in the charm quark sectors. In my invited overview I discussed some of these recent new developments, including theoretical developments, new production mechanisms such as B decays and double charmonium production, and the discovery of several of the many new candidates for excited charmonia, charm meson molecules, and hybrid (excited glue) mesons, in both charmonium and light quark sectors. In this writeup, due to length constraints I will restrict my discussion to a few examples of …

Latest Developments in Heavy Meson Spectroscopy

I discuss developments in heavy meson spectroscopy. In particular, I consider the system of $c{\bar s}$ mesons and the puzzling state X(3872), with focus on the strategies for their classification.

New Spectroscopy of Heavy Mesons

I discuss the most recently discovered open charm mesons, both with and without strangeness. By exploiting the heavy quark limit, strong decay widths of such mesons are computed. Comparison between theoretical predictions and experimental measurements are useful to assign the right quantum numbers to such states. As for hidden charm mesons, I consider the case of X(3872). Analysis of its radiative decays to $J/ψγ$ and $ψ(2S) γ$ shows the plausibility of the identification with $χ_{c1}(2P)$.

Spectroscopy of $\mathbf{B_c}$ mesons and the possibility of finding exotic $\mathbf{B_c}$-like structures

The bottom-charmed ($B_c$) mesons are more stable than their charmonium ($c\bar c$) and bottomium ($b\bar b$) partners because they cannot annihilate into gluons. However, the low production cross-sections and signal-to-background ratios avoided until now their clear identification. The recent experimental results reported by CMS and LHCb at CERN open the possibility of having a $B_c$ spectrum as complete as the ones of charmonium and bottomonium. Motivated by this expectation, we compute bottom-charmed meson masses in the region energies in which decay meson-meson thresholds are opened, looki…

CMS合作组观测到的四粲夸克物质：高精度强子谱学发展的见证

Four-Charm-Quark Matter from the CMS Collaboration as a Witness of the Development of High-Precision Hadron Spectroscopy

CMS合作组在双J/ψ不变质量谱中观测到X(6600)、X(6900)及7134 MeV新结构，为四粲夸克物质研究提供关键证据，标志着高精度强子谱学的显著进展。

Strong decays analysis of excited nonstrange charmed mesons: Implications for spectroscopy

The strong decays of $D_1(2420)^0$, $D_2^*(2460)^0$, $D_2^*(2460)^+$, $D_2^*(2460)^-$, $D(2550)^0$, $D_J^*(2600)^0$, $D(2740)^0$, $D_3^*(2750)^0$, $D_3^*(2750)^+$, $D_3^*(2750)^-$, $D_J(3000)^0$, $D{_{J}^*}(3000)^0$ and $D_2^*(3000)^0$ resonance states are analyzed in the heavy quark mass limit of Heavy Quark Effective Theory (HQET). The individual decay rates and the branching ratios among the strong decays determine their spin and parity. From such states the Regge trajectories are constructed in $(J, M^2)$ and $(n_r, M^2)$ planes and further predict the masses of higher excited states (1$^1…

Open-charm meson spectroscopy

We present a theoretical framework that accounts for the new $D_J$ and $D_{sJ}$ mesons measured in the open-charm sector. These resonances are properly described if considered as a mixture of conventional $P-$wave quark-antiquark states and four-quark components. The narrowest states are basically $P-$wave quark-antiquark mesons, while the dominantly four-quark states are shifted above the corresponding two-meson threshold, being broad resonances. We study the electromagnetic decay widths as basic tools to scrutiny their nature. The proposed explanation incorporates in a natural way the most r…

Charmed baryon in a string model

Charm spectroscopy has studied under a string model. Charmed baryons are composed of diquark and charm quark which are connected by a constant tension. In a diquark picture, the quantum numbers $J^P$ of confirmed baryons are well assigned. We give energy predictions for the first and second orbital excitations. We see some correspondences with the experimental data. Meanwhile, we have obtained diquark masses in the background of charm quark which satisfy a splitting relation based on spin-spin interaction.

New meson spectroscopy with open charm and beauty

All the available experimental information on open charm and beauty mesons is used to classify the observed states in heavy quark doublets. The masses of some of the still unobserved states are predicted, in particular in the beauty sector. Adopting an effective Lagrangian approach based on the heavy quark and chiral symmetry, individual decay rates and ratios of branching fractions are computed, with results useful to assign the quantum numbers to recently observed charmed states which still need to be properly classified. Implications and predictions for the corresponding beauty mesons are p…

New Spectroscopy with PANDA at FAIR: X, Y, Z and the F-wave Charmonium States

Charm and charmonium physics have gained renewed interest in the past decade. Recent spectroscopic observations strongly motivate these studies. Among the several possible reactions, measurements in proton-antiproton annihilation play an important role, complementary to the studies performed at B-factories. The fixed target PANDA experiment at FAIR (Darmstadt, Germany) will investigate fundamental questions of hadron and nuclear physics in the interactions of antiprotons with nucleons and nuclei. With reaction rates as large as 2*10^7 interactions/s, and a mass resolution 20 times better as co…

Spectroscopy of the hidden-charm $[qc][\bar q \bar c]$ and $[sc][\bar s \bar c]$ tetraquarks

We calculate the spectrum of $q\bar q c \bar c$ and $s\bar s c \bar c$ tetraquarks, where $q$, $s$ and $c$ stand for light ($u,d$), strange and charm quarks, respectively, in a relativized diquark model, characterized by one-gluon-exchange (OGE) plus confining potential. In the diquark model, a $q\bar q c \bar c$ ($s\bar s c \bar c$) tetraquark configuration is made up of a heavy-light diquark, $q c$ ($sc$), and anti-diquark, $\bar q \bar c$ ($\bar s \bar c$). According to our results, 13 charmonium-like observed states can be accommodated in the tetraquark picture, both in the hidden-charm ($…

Spectroscopy of Mesons with Heavy Quarks

I will give a concise overview of mesons with heavy quarks including p-wave charmed mesons and charmonium (or charmonium-like) states such as X(3872), Y(4260), X(3940), Y(3940), Z(3930) etc. The effect from the nearby S-wave open channels on the quark model spectrum is emphasized.

Excited and exotic charmonium spectroscopy from lattice QCD

We present a spectrum of highly excited charmonium mesons up to around 4.5 GeV calculated using dynamical lattice QCD. Employing novel computational techniques and the variational method with a large basis of carefully constructed operators, we extract and reliably identify the continuum spin of an extensive set of excited states, states with exotic quantum numbers (0+-, 1-+, 2+-) and states with high spin. Calculations are performed on two lattice volumes with pion mass approximately 400 MeV and the mass determinations have high statistical precision even for excited states. We discuss the re…

Charm Decays and Spectroscopy at BABAR

We present searches for rare charm decays of the form $X_c^+ \to h^{\pm} \ell^{\mp} \ell^{(')^+}$, where $X_c^+$ is a charm hadron either $D^+$, $D_s^+$, or $Λ_c^+$, and $\ell^{(')^{\pm}}$ is an electron or muon. These modes are based on 384 $fb^{-1}$ of $e^+ e^-$ annihilation data collected at the $Υ(4S)$ resonance with the BABAR detector at the SLAC National Accelerator Laboratory. We also present the flavor-changing neutral-current decays $D^0 \to e^+e^-$, $D^0 \to μ^+ μ^-$, and $D^0 \to e^{\pm} μ^{\mp}$ that corresponds to an integrated luminosity of 468 $fb^{-1}$ of data. The decay $D^0 \…

D and D_s meson spectroscopy

Results are presented for the low-lying spectrum of D and D_s mesons calculated in lattice QCD using 2+1 flavor Clover-Wilson configurations made available by the PACS-CS collaboration. For the heavy quark, the Fermilab method is employed. The main focus is S- and P-wave states of charmed and charmed-strange mesons, where previous lattice QCD results have been mostly from quenched calculations. In addition to the ground states, some excited states are extracted. To check the method, calculations of the charmonium spectrum are also carried out. For charmonium, the low-lying spectrum agrees favo…

Excited spectroscopy of charmed mesons from lattice QCD

We present spectra of highly excited D and Ds mesons up to around 3.8 GeV determined using dynamical lattice QCD. We employ novel computational techniques and the variational method with a large basis of carefully constructed operators in order to extract and reliably identify the continuum spin of an extensive set of excited states. These include states with high spin and states identified as having an explicit gluonic contribution. Calculations were performed on two volumes, both with a pion mass of approximately 400 MeV, achieving a high statistical precision for both ground and excited sta…

在未淬火粲偶素谱学背景下利用$B^+\to K^+μ^+μ^-$数据重新评估$ψ(4160)$共振参数

Reevaluating the $ψ(4160)$ Resonance Parameter Using $B^+\to K^+μ^+μ^-$ Data in the Context of Unquenched Charmonium Spectroscopy

针对$ψ(4160)$测量质量偏高的问题，本研究基于未淬火粲偶素谱，利用$B^+\to K^+μ^+μ^-$数据重测其质量为4145.76±4.48 MeV，修正了此前的高估结果，对强子谱学和新物理寻找有重要意义。

Evidence for further charmonium vector resonances

We discuss the shape of threshold signals in production cross sections of the reaction e+ + e- --> D* + antiD*, at the opening of the D(s)* antiD(s)* and Lambda(c)+ Lambda(c)- channels. Furthermore, evidence for the 3D, 5S, 4D, 6S, 5D, 7S, 6D, and 8S charmonium vector resonances is presented, on the basis of data recently published by the BaBar Collaboration. Central masses and resonance widths are estimated. Confirmation of these resonances would be a huge step in lifting the precision level of hadron spectroscopy towards that of atomic spectroscopy, with far-reaching consequences for theory.

Charmed baryons on the lattice

We discuss the significance of charm baryon spectroscopy in hadron physics and review the recent developments of the spectra of charmed baryons in lattice calculations. Special emphasis is given on the recent studies of highly excited charm baryon states. Recent precision lattice measurements of the low lying charm and bottom baryons are also reviewed.

Multiquark contributions to charm baryon spectroscopy

We study possible multiquark contributions to the charm baryon spectrum by considering higher order Fock space components. For this purpose we perform two different calculations. In a first approach we do a coupled-channel calculation of the $ND$ system looking for molecular states. In a second step we allow for the coupling to a heavy baryon--light meson two-hadron system looking for compact exotic five--quark structures. Both calculations have been done within the framework of a chiral constituent quark model. The model, tuned in the description of the baryon and meson spectra as well as the…

Physics of tau and charm

The physics of tau and charm started in early 70's after J/$ψ$ and $τ$ were discovered. Since then several dedicated accelerators and experiments were built with increasing luminosities and studies on light hadron spectroscopy, charmonium, electroweak and QCD were never interupted. New interests and surprises are not rare in this area. With the newly built BEPCII/BESIII, an even brighter future is foreseen.