The BESIII experiment at the Beijing Electron Positron Collider (BEPCII) has accumulated the world's largest samples of direct $e^+e^-$ collisions in the $τ$-charm region. From the collected samples, which include $e^+e^-$ annihilations at $J/ψ$, $ψ'$, $ψ$(3770) peaks and in the region from 3.8$\,$GeV to 4.6$\,$GeV, BESIII has produced many new physics results in the spectroscopy, transitions, and decays of charmonium(-like) states. This talk will cover the latest results over a wide range of topics from radiative and hadronic transitions among charmonium states, as well as the productions and decays of the $XYZ$ states.
In recent years, lots of studies of charmonium decays have been performed at BESIII based on large data samples of $J/ψ$, $ψ(3686)$ and $ψ(3770)$. Recent results in searches for radiative transitions of $ψ(3770)$ and rare phenomena in charmonium decays, and studies of light hadrons structures and properties will be presented.
The recent measurement results of exotic charmonium-like states, the so called XYZ particles, at BESIII have been presented. I mainly discussed the charged Zc(3900) state, its neutral partner, and possible excited states.
We report the latest outcomes for the Charmonium system investigation on 226x10^6 J/Psi and 106x10^6 Psi' events collected with the BESIII detector at the BEPCII e+e- collider.
In 2009, the BESIII experiment has collected about 225M $\jpsi$ and 106M $\psip$ samples, both of which are the world largest on-peak charmonium production. Based on these dataset, BESIII has made great effort on the study of the charmonium decays, some important of which have been reviewed in this proceeding. In addition, a searching for new physics through the $CP/P$ violation process is reported.
In this talk, we will present the results on the charmonium spin singlet states below the open charm threshold, including h_c, η_c, and η_c(2S). The masses, widthes, and production rates of these states will be reported. The results are based on a data sample of 106 million ψ' events collected with the BESIII experiments at the BEPCII collider.
In the quark model, hadrons are dominantly bound states of quark-antiquark pairs (mesons) or three quarks (baryons), but QCD also allows hadronic states to be composed of more quarks bound together. Recently, BESIII, Belle and LHCb have confirmed the existence of four-quark and pentaquark candidates. These new states, along with experimentally observed resonances that do not fit well into the charmonium and bottomonium spectra, present challenges and opportunities for strong interaction theory. In this talk, I will review results on charmonium-like exotic quark states that have been observed b…
Despite the successes of the standard model, the non-perturbative dynamics of the strong interaction are not fully understood yet. Charmonium spectroscopy serves as an ideal tool to shed light on the dynamics of the strong interaction such as quark confinement and the generation of hadron masses. The BESIII collaboration studies extensively the strong interaction and various aspects that could shed light on physics beyond the standard model via copious e$^+$e$^-$ collisions at the BESIII/BEPCII facility in Beijing, China, in the charmonium mass regime. I present a few of the recent results wit…
Hadron spectroscopy is one of the most important physics goals of BESIII. BESIII brings great opportunities to study the XYZ states of charmonium by directly producing the Y states up to 4.6 GeV. High statistics of charmonium decays collected at BESIII provide an excellent place for hunting gluonic excitations and studying the excited baryons. Recent results of light hadron spectroscopy and charmonium spectroscopy from BESIII will be reported.
Based on the data samples collected at the energies of $J/ψ$, $ψ(3686)$, $ψ(3770)$ and $ψ(4040)$ resonances with the BESIII detector at the BEPCII storage ring, we present charmonium decays in two aspects. One is the search for baryonic decays of $ψ(3770)$ and $ψ(4040)$, including $Λ\barΛπ^+π^-$, $Λ\barΛπ^0$, $Λ\barΛη$, $Σ^+ \barΣ^-$, $Σ^0 \barΣ^0$, $Ξ^-\barΞ^+$ and $Ξ^0\barΞ^0$. None are observed, and upper limits are set at the 90% confidence level. The other is the light hadron spectroscopy from charmonium radiative decays, including the spin-parity analysis of the $p\bar p$ mass-threshold …
With about 12 fb$^{-1}$ collected XYZ data sets, BESIII continues the exploration of the exotic charmonium-like states. In this talk, recent results on the measurements of the spin-parity determination of $Z_{\rm c}(3900)$, as well as on line-shapes of $e^+e^- \rightarrow J/ψ\,ππ, h_{\rm c}ππ, ψ(2S)\,π^0π^0/π^+π^-$, and $π^+ D^0 D^{*-}$ from open charm are discussed. Also, the recent observation of $e^+ e^- \rightarrow ϕχ_{c1/2}$ at $\sqrt(s)=4.6$ GeV is reported.
Results based on 106 M $ψ'$ events and about 226 M $J/ψ$ events acquired with the BESIII detector at BEPCII are reported, including a confirmation of the BESII $p\bar{p}$ threshold enhancement in $J/ψ\to γp\bar{p}$, branching ratios for $χ_{cJ} \to π^0 π^0$ and $ηη$, and first measurements of the branching ratios for $ψ' \to π^0 h_c$ and $h_c \to γη_c$, as well as measurements of the mass and width of the $h_c$. Also reported are first observations of the two photon process $ψ' \to γγJ/ψ$ and $f_0(980) - a_0(980)$ mixing.
Charmonium is a bound state of a charmed quark and a charmed antiquark, and a charmoniumlike state is a resonant structure that contains a charmed quark and antiquark pair but has properties that are incompatible with a conventional charmonium state. While operating at center-of-mass energies from 2 to 4.9 GeV, the BESIII experiment can access a wide mass range of charmonium and charmoniumlike states, and has contributed significantly in this field. We review BESIII results involving conventional charmonium states, including the first observation of M1 transition $ψ(3686) \to γη_c(2S)$ and the…
We present a selection of recent results from the BESIII collaboration, including both charmonium and $D$ meson physics. We first discuss the observation of a charged, charmonium-like state, the $Z_c(3900)$. Conventional charmonium topics include a search for lepton flavor violation, studies of $χ_{cJ} \to γγ$ decays, and mass and width determinations for the $h_c$, $η_c(1S)$, and $η_c(2S)$. We finish with results on the decay constant $f_D$ from $D^+ \to μ^+ ν$ and on form-factors in $D^0 \to K^- e^+ ν, π^- e^+ ν$.
Charmonium spectroscopy provides strong guidelines to effective field theories, thereby gaining insight into quark confinement and the generation of hadron masses. Hadronic transitions between charmonium states have been measured with unprecedented high precision with the BESIII spectrometer at IHEP Beijing, China. We present systematic studies of isospin-violating decays in charmonium, such as $ψ' \rightarrow π^{0} J/ψ$, $ψ' \rightarrow π^{0} h_{c}$, $e^{+}e^{-} \rightarrow π^{0} J/ψ$ at $\sqrt{s}=$ 4.009 GeV, and their improved measurements of their branching fractions.
With the ability to run above 4~GeV, the BESIII experiment located in the Beijing Electron Positron Collider (BEPCII), has becoming a pioneer in searching and studying charmoniumlike states ($XYZ$ particles). In 2013, BESIII Collaboration discovered a charged charmoniumlike state $Z_c(3900)$, which is confirmed immediately experimentally, and provides the best candidate for a four quark state by now. Continuous studies by BESIII Collaboration show new decay behavior of $Z_c(3900)$, and there are possible partner particle $Z_c(4020)/Z_c(4025)$ existing. By scanning above 4~GeV, BESIII also reve…
The recent results on Charmonium and Charmonium-like states at BESIII are reviewed, including the observation of $\rm Z_{cs}(3985)$ state, the study of the new decay modes of $ψ_2(3823)$ state, observation of resonance structure in $\rm e^+e^- \to π^+π^-ψ_2(3823)$ process, the study of the $\rm e^+e^- \to K^+K^-J/ψ$ process, cross section measurement of $\rm e^+e^- \to ωπ^0$ and $ωη$ process, branching fraction measurement of $ψ(3686)\to\barΣ^0Λ+ c.c.$ process. Decay channels for $χ_{cJ} \to Λ\barΛ$, $χ_{cJ} \to Λ\barΛη$, $ψ(3686) \to Λ\barΛω$ and $η_c(2S)\to3(π^+π^-)$ are also discussed. The …
The BESIII Experiment at the Beijing Electron Positron Collider (BEPCII) collected large data samples for electron-positron collisions with center-of-mass above 4 GeV. The analysis of these samples has resulted in a number of surprising discoveries, such as the discoveries of the electrically charged $\mathrm{Z_c}$ structures, which, if resonant, cannot be accommodated in the traditional charm quark and anti-charm quark picture of charmonium. In this talk, we will review the current status of the analyses of the exotic states, as well as a number of other interesting features in the new BESIII…
Recently, LHCb experiment announced a 3.5$σ$ evidence for direct CP violation in $D^0$ decay by looking at the difference between $A_{CP}(D^0\rightarrow K^+K^-)$ and $A_{CP}(D^0\rightarrow π^+π^-)$. This is the first evidence of CP violation in charm system, which may indicate new physics beyond the Standard Model. Motivated by this measurement, we review rare processes in charmonium decay, especially, the weak decay, $C$ or $P$ violated decay and lepton flavor violated decays. In case the new physics appears in charm sector, these rare decays of charmonium states will provide opportunity to s…
A selection of results from electron-positron collisions at BESIII are reviewed. The results presented here illustrate the wide range of physics topics that can be studied using the Beijing Electron Positron Collider~(BEPC). At low collision energies, the cross section for $e^+e^-\to π^+π^-$ provides much-needed input into theoretical calculations of the anomalous magnetic moment of the muon, and the reaction $e^+e^-\to p\bar{p}$ provides access to the electromagnetic form factors of the proton. In the charmonium region, a large sample of $ψ^\prime$ decays can be used to measure new decay mode…
Based on $ψ(3686)$ decays of 106 million, the 1.31 billion J/psi events and a data sample of $ψ(3770)$ with $2.9~fb^{-1}$ integrated luminosity, many analyses are performed. Exclusively baryonic decays of the $ψ(3770)$, the radiative transition $ψ(3770)\toγη_c(2S)$, the $ψ(3770)$ transition to $χ_{cJ}$, isospin violation decay $χ_{c0,2}\toπ^0η_c$, the $C-$parity violation decays $J/ψ\toγγ,γϕ$ are searched for, but no significant signals are observed, and upper limits are set for these decays. The decays of $ψ(3770)\toγχ_{c1}$ and $J/ψ\toπ^0ϕ$ signals are observed. These measurements provide mo…
With its unique data samples at energies of 3.8--4.6 GeV, the BESIII experiment made a significant contribution to the study of charmonium and charmonium-like states, i.e., the XYZ states. We review the results for observations of the Zc(3900) and Zc(4020) states, the X(3872) in e+e- annihilation, and charmonium psi(1^3D_2) state, as well as measurements of the cross-sections of omega chi_cJ and eta J/psi, and the search for e+e- to gamma chi_cJ and gamma Y(4140). We also present data from BESIII that may further strengthen the study of the XYZ and conventional charmonium states, and discuss p…
Several states that couple to one light-meson and a heavy-charmonium are recently reported, including the $Z_c(3900)$ and $Z_c(4020)$. These states cannot be interpreted within the constituent quark-model of mesons, and are good candidates for a new form of quark matter, four-quark matter. A review of recent results on new charmonium-like states studied at BESIII is presented.
Despite the successes of the standard model, the non-perturbative dynamics of the strong interaction are not fully understood yet. Charmonium spectroscopy serves as an ideal tool to shed light on the dynamics of the strong interaction such as quark confinement and the generation of hadron masses. The BESIII collaboration studies extensively the strong interaction and various aspects that could shed light on physics beyond the standard model via copious e$^+$e$^-$ collisions at the BESIII/BEPCII facility in Beijing, China, in the charmonium mass regime. We present a few of the recent results wi…
The BESIII experiment at BEPCII at IHEP in Beijing/China has collected the world largest data sets in the $τ$-charm region and it is well suited to cover a rich hadron physics programme, including charmonium and open-charm spectroscopy, $R$-scan or electromagnetic form factor measurements, and many more. In particular, the unique data sets between 3.8 and 4.6\,GeV allow for discoveries and precision measurements of the interesting charmonium-like (exotic) `XYZ' states. The recently published precision cross-section measurement for $Y$ states is discussed as well as the first observation of the…
A brief review of experimental results on charmonium and charmonium-like hadron spectroscopy at B-factories is presented. A special focus is put on recent results of eta_c and eta_c(2S) study, X(3872) radiative decays, omega J/psi final state study and search for charmonium production in radiative Upsilon decays.
The latest results of CMS in the area of exotic quarkonium decays will be presented: observation of a peaking structure in $J/ψΦ$ mass spectrum in the decay $B^\pm \rightarrow J/ψΦK^\pm$, search for new bottomonium states in $Υ(1\mathrm{S})π^+π^-$ mass spectrum, measurement of prompt $J/ψ$ pair production.
We report some recent results on charmonium spectroscopy and hadron spectroscopy from BESIII experiment, including the measurements of the masses and widths of $h_c$, $η_c$, $η_c(2S)$ and some new resonances around 2 GeV. The results are based on a data sample of 106 million $ψ^\prime$ events and 226 million J/$ψ$ events collected with the BESIII detector at the BEPCII collider.
Many unexpected charmonium-like states have recently been observed above the $D\overline{D}$ threshold, which features can't be explained by the conventional quark models. These states are known as XYZ mesons. The study of the radiative transition among these states can provide the important features of XYZ states. This study has recently been performed by the BESIII using the large data samples collected at different center-of-mass energies above 3.8 GeV. This report summarizes the recent results of XYZ radiative transitions at BESIII.
Stimulated by the recent BESIII observation of a new resonance in $e^+ e^- \to ωχ_{c0}$ and by the fact that this state is consistent with our predicted $ψ(4S)$, in this work we estimate the meson loop contribution to $ψ(4S) \to ωχ_{c0}$. The evaluation indicates that our theoretical estimate can overlap with the experimental data in a reasonable parameter range. This fact shows that introduction of the missing higher charmonium $ψ(4S)$ provides a possible explanation to the recent BESIII observation. The upper limit of a branching ratio of $ψ(4S) \to ηJ/ψ$ is also predicted as $1.9 \times 10^…
The B factories provide a unique playground for studying the properties of conventional and exotic charmonium states. We present recent results in initial state radiation and two-photon fusion, obtained using the full data set collected by the BaBar experiment. Amongst BaBar 's harvest presented in this talk, the determination of the quantum numbers of the X(3915) resonance, a body of concording evidence pointing to JPC = 1++ for the X(3872), and updates on the family of the Y resonance to the full integrated luminosity.
The recent results on charmonium and charmoniumlike states from Belle experiment are reviewed. We summarise searches in $B$ decays for possible $X$-like states in final states containing $η_c$. The new measurement of $e^+e^-\toπ^+π^-ψ(2S)$ improves the determination of the properties of $Y(4360)$ and $Y(4660)$. The fits including $Y(4260)$ are performed. Evidence for a charged charmoniumlike structure at $4.05~{\rm GeV}/c^2$ is observed in the $π^{\pm}ψ(2S)$ intermediate state in the $Y(4360)$ decays. Belle also updates the measurement on $e^+e^-\to KKJ/ψ$ via initial state radiation using the…
At present very large data samples in the energy region of 2.0-4.6 GeV were accumulated by the BESIII detector, which is operated in the upgraded Beijing electron positron collider (BEPCII). These data samples provide an unprecedented opportunity in the study of light hadron spectra and charmonium(-like) decays. We review some experimental analyses related to isospin violations at BESIII in this proceeding, which can be classify into three categories: isospin violating processes with a $f_0(980)$ or $a^0_0(980)$ production, isospin violating processes with baryon final states, and isospin viol…
We present the most recent results from the BESIII experiment. This review covers the studies of charmonium decays, light hadron spectroscopy and charm physics. Especially, the prospects for weak decays of charm mesons are addressed at the BESIII.
We report the recent evidence for a new narrow structure, Y(4140), decaying to the $J/ψϕ$ final state, in exclusive $B^+\to J/ψϕK^+$ decays in a data sample corresponding to an integrated luminosity of 2.7 \ifb collected at the CDF II detector. This narrow structure with its mass well above open charm pairs is unlikely to be a candidate for a conventional charmonium state. From a study of the X(3872) mass and width based on the world's largest sample of $X(3872)\to J/ψπ^+π^-$ decays, we find that our X(3872) signal is consistent with a single state, and leads to the most precise measurement of…
With the help of the largest data samples of $J/ψ$ and $ψ(2S)$ events ever produced in $e^+e^-$ annihilations, the three singlet charmonium states, $η_c(1S)$, $η_c(2S)$ and $h_c(1P)$, have been extensively studied at the BESIII experiment. In this review, a survey on the most recent results, including a series of precision measurements and observations of their new decay modes, is presented, which indicates the further investigations on their decays are needed to understand their decay mechanisms and have precision tests of the theoretical models. At present, about eight times larger data samp…
In this paper, we present a new experimental progress in brief on the recent observation of the charged charmonium-like state Z_c(4020)^{+/-} states and its iso-spin partner Z_c(4020)^{0} in pi pi hc process at the BESIII experiment. The charged Z_{c}(4020) is its decay into π^{+/-} hc final state, and carries electric charge, thus it contains at least four quarks. The observation of both charge and neutral state makes Z_{c}(4020) the first iso-spin triplet Z_{c} state observed in experiment.
School of Physical Science and Technology, Lanzhou University（兰州大学物理科学与技术学院）；Frontiers Science Center for Rare Isotopes, Lanzhou University（兰州大学稀有同位素前沿科学中心）
Since few years, a new family of exotic states has been appearing above the open-heavy meson thresholds: the so-called $XYZ$ states. BESIII at the BEPCII $e^+e^-$ collider plays a unique role in the study of those particles in the charmonium sector. Changing the beam energy, BESIII can collect large data samples by means of scans of the resonant region, accessing directly to all vector states. As part of a larger upgrade program, BESIII has planned to increase the center of mass energy to reach $4.7$ GeV: this will allow BESIII to investigate the nature of the $Y(4660)$, that was at first obse…
The Beijing Spectrometer (BESIII) collaboration uses $e^+e^-$ collisions in the tau-charm energy region to study a broad spectrum of topics. These include studies of light mesons and light baryons, studies of charmonium, including exotic mesons and baryons containing charmonium, studies of charmed mesons and baryons, studies of QCD and tau physics, as well as searches for new physics. The following is a Snowmass white paper that outlines the BESIII accomplishments and potential in each of these areas.
One of the most intriguing puzzles in hadron spectroscopy are the numerous charmonium-like states observed in the last decade, including charged states that are manifestly exotic. The $BABAR$ and Belle experiments have extensively studied those in B meson decays, initial state radiation processes and two photon reactions. We can question what we have understood after 11 year search in this field, and try to combine results to conclude on what these new unpredicted resonant states are, and how they can be accommodated in the theory. Big effort has been made from theoretical and experimental poi…
There are many exotic properties of the charmonium and charmoniumlike states above $D\bar{D}$ threshold. The recent experimental results from BaBar and Belle on the new and conventional charmonium states are reviewed in this talk.
BESIII had collected large data samples on $J/ψ$ and $ψ^\prime$ peaks during the first run in 2009. From 2010 to 2011, about 2.9 fb$^{-1}$ integrated luminosity were obtained on the peak of $ψ(3770)$ for open charm physics. We review recent results on charmonium decays and hadron spectroscopy. The prospects on open charm physics are also discussed.
Light hadron spectroscopy plays an important role in understanding the decay dynamics of unconventional hadronic states, such as strangeonium and glueballs. BESIII provides an ideal avenue to search for these exotic states thanks to a huge amount of data recorded at various energy points in the tau-charm mass region including J/psi resonance. This report summarizes recent results of the BESIII experiment related to the glueballs and strangeonium-like states.
We review recent results on charmonium-like exotic states from the Belle experiment. The two-photon process $γγ\to ϕ\jpsi$ is measured to search for Y(4140). No signal for the $Y(4140) \to ϕ\jpsi$ is observed. But a narrow peak with a significance of 3.2$σ$ deviations including systematic uncertainty is observed at 4350.6 MeV/$c^2$ that we named X(4350). We also search for charmonium-like states, including X(3872), Y(4140), X(3915) and X(4350), in $Υ(1S)$ and $Υ(2S)$ radiative decays. No significant signal of any charmonium-like state is observed. The processes $γγ\to VV$ ($V=ω$ or $ϕ$) are al…
Search for Charmonium(-like) states decaying into the $Ω^-\barΩ^+$ final states
School of Physical Science and Technology, Lanzhou University（兰州大学物理科学与技术学院）；Frontiers Science Center for Rare Isotopes, Lanzhou University（兰州大学稀有同位素前沿科学中心）
Tests of CP symmetry in entangled hyperon anti-hyperon pairs at BESIII
Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）；University of Chinese Academy of Sciences（中国科学院大学）；Uppsala University（乌普萨拉大学）；National Centre for Nuclear Research（波兰国家核子研究中心）；INFN Sezione di Perugia（意大利国家核物理研究院佩鲁加分部）；Università di Perugia（佩鲁贾大学）；Lanzhou University（兰州大学）；Institute of Physics, Henan Academy of Sciences（河南省科学院物理研究所）
We review selected lattice results on the charmonium spectrum and first attempts to search for the existence of exotic states. The hadro-quarkonium model was proposed to interpret some of the exotic states as a quarkonium core inside a hadron. We present a lattice study of the hadro-quarkonium model in the limit of static quarks. The charm quark decouples in low energy observables and binding energies of charmonium. In a model calculation we are able to evaluate the corrections to decoupling of the charm quark in the continuum.
I will report on the recent LHCb results on the evidence for the decay $X(3872)\rightarrowψ(2S) γ$, and on the improved measurement of the mass and width of the $Z(4430)^-$, the determination of its quantum numbers and the observation of its resonant character.
A number of charmonium-(bottmonium-)like states have been observed in $B$-factory experiments. Recently the BESIII experiment has joined this search with a unique data sample collected at the different center of mass energies ranging from 3.9 GeV to 4.42 GeV in which they found new charmonium-like states with non-zero electric charge. We review the status of experimental searchs for quarkomonium-like states and also other types of non-$q\bar{q}$ meson or non-$qqq$ baryons that are predicted by QCD-motivated models. We mainly focus on results from the $B$-factories and BESIII.
Charmonium, the spectroscopy of c\bar{c} mesons, has recently enjoyed a renaissance with the discovery of several missing states and a number of unexpected charmonium-like resonances. The discovery of these new states has been made possible by the extremely large data samples made available by the B-factories at the Stanford Linear Accelerator Center and at KEK in Japan, and at the CESR e^+e^- collider at Cornell. Conventional c\bar{c} states are well described by quark potential models. However, many of these newly discovered charmonium-like mesons do not seem to fit into the conventional c\b…
