12 pages, 12 figures. To appear in International Journal of Modern Physics: Conference Series for The XXXIII international symposium on Physics in Collision, Beijing, P. R. China from 03 - 07 September 2013
In this report I review some results on the charmonium and light hadron spectroscopy mainly from BESIII and Belle experiments. For the charmonium, the contents include the observation of $ψ(4040)/ψ(4160) \to η\jpsi$, the measurements of the $η_c/η_c(2S)$ resonance parameters and their decays, the evidence of the $ψ_2(1^3D_2)$ state in the $χ_{c1}γ$ mass spectrum. For the light hadron spectroscopy, the contents include the $X(1835)$ research in $e^+e^- \to \jpsi + X(1835)$ and $γγ\to η' π^+ π^-$ processes, and the analysis of the $ηη$, $ωϕ$, $ϕϕ$ and $ωω$ mass spectra in low mass region.
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.
During the last few years there has been a renaissance in charm and charmonium spectroscopy with higher precision measurements at the $ψ^{'}$ and $ψ(3770)$ coming from BESII and CLEOc and many new discoveries coming from B-factories. In this paper, I review some new results on "classical" charmonium and $e^+ e^- \to$ hadrons using B-factory Initial State Radiation and two photon events.
In this talk, I review the recent experimental developments on charmonium. These mainly include the precision measurements of spin-singlet states $\etac$, $\etac(2S)$, $h_c$, studies of the charmonium-like states X(3872) and the $Y$ states. Charmonium transitions and decays are also discussed.
Charmonium spectroscopy gained renewed interest after the discovery in 2003 of the unpredicted X(3872) charmonium-like state, above the $D\overline{D}$ threshold. To date many charmonium-like states above the $D\overline{D}$ threshold have been claimed. Some of these states do not easily fit the conventional charmonium picture. In this article we review recent experimental results in this field, reported by the BaBar and Belle Collaborations.
The charmonium-like states, Y(4260), Y(4350), produced via initial state radiation, as well as the X(3872), and Y(3940), produced in B meson decays from the BABAR B-factory are reviewed. These mesons do not seem consistent with conventional charmonium models, and several alternate hypotheses have been proposed to explain these new discoveries.
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.
Over the past few years, there has been a lot of progress in the areas of charm and charmonium spectroscopy, in large part due to the very large data samples being accumulated at the e+e- B-Factories. In this presentation I will focus on results in three areas: the X/Y/Z charmonium-candidate states, the D_sJ charmed-strange mesons, and newly-discovered charmed baryons. Note the absence of a section on pentaquarks: all B-Factory searches for pentaquarks, charmed or otherwise, have not yielded any observation of such states.
In this talk, we review the recent experimental developments on charmonium and charm spectroscopy base on the data samples taken by the BESIII, Belle, LHCb and CMS experiments. We concentrate on the resonant parameter measurement of $χ_{cJ}$, $η_{c}$, $η_{c}(2S)$, observation of $ψ(1^{3}D_{3})$ candidate and alternative $χ_{c0}(2P)$ candidate, observation of excited $B_{c}$ states, $Ξ(2930)$ states, excited $Ω_{c}$ states and doubly charm baryon, and the study of $Λ_{c}^{*}$ states.
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.
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.
Identification of charmonium states at hadron colliders has mostly been limited to leptonic decays of the J/ψ. In this paper we present and algorithm to identify hadronic decays of charmonium states (J/ψ, ψ(2S), χ_{c0,1,2}) which make up the large majority of all decays. The algorithm is able to identify hadronic $J/ψ$ decays with an efficiency of 36\% while suppressing a background of quark and gluon jets by a factor 100.
Since 2003 several states in the charmonium mass region were discovered. While in the conventional c c-bar spectrum some states are missing, the number of states observed up to now is larger than empty spaces in the c c-bar spectrum. This, together with other difficulties to explain observed states as a c c-bar mesons triggered discussions on a possible exotic interpretations. In this proceedings we present current experimental status from B-factories of the so called X, Y and Z states.
In this talk, I review the recent experimental results on charmonium spectroscopy from BESIII, Belle, BaBar and CLEOc. Below the open-charm threshold, the masses and widths of spin-singlet states eta_c, eta_c(2S), h_c are measured with high precision. Above the threshold, chi_{c2}(2P) is identified in the process gamma gamma -> chi_{c2}(2P) -> gamma D bar{D}; Evidence of X(3823) is found in the M(chi_{c1} gamma) invariant-mass distribution for B -> gamma chi_{c1} K decays, the measured properties are consistent with the missing psi_2(1^{2}D_2) state.
The bottomonium and charmonium systems have long proved to be a rich source of QCD physics. Recent CLEO contributions in three disparate areas are presented: (1) the study of quark and gluon hadronization using $Υ$ decays; (2) the interpretation of heavy charmonium states, including non-$c\bar{c}$ candidates; and (3) the exploration of light quark physics using the decays of narrow charmonium states as a well-controlled source of light quark hadrons.
We report measurements of the branching fractions for the decays B->D_s1(2536)+ anti-D(*), where anti-D(*) is anti-D0, D- or D*-, and study of B->X(3872) K with X(3872) decaying to D*0 anti-D0 using a sample of 657 million B anti-B pairs recorded at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.
Belle and BaBar experiments at the KEKB and PEP-II B-factories provide also an excellent environment for spectroscopy studies. In this report we present recent results in the field of charmonium spectroscopy, focusing on new charmonium-like states observed in B decays, and on $J^{PC}=1^{--}$ resonances created in $e^+ e^-$ annihilation through the photon radiative return.
Hadron physics represents the study of strongly interacting matter in all its manifestations and the understanding of its properties and interactions. The interest on this field has been revitalized by the discovery of new light hadrons, charmonium- and bottomonium-like states. I review the most recent experimental results from different experiments.
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…
Studies of charmonium properties and production mechanism started with the discovery of $J/ψ$ meson. Since more than 40 years the charmonium production mechanism is still not entirely understood. Following the era of investigations at $e^+e^-$ machines, nowadays, charmonium states are copiously produced at hadron colliders, that allows systematic studies of their resonance parameters, production observables and decays. Despite large production rates, many charmonium states are barely studied due to the complications of their reconstruction against a large background level. The LHCb experiment …
I present preliminary results on the search for $h_c$ in its $η_cγ$ and $J/ψπ^0$ decay modes. We observe an excess of η_cγ$ events near 3526 MeV that has a probability ${\cal P} \sim 0.001$ to arise from background fluctations. The resonance parameters are $M=3525.8 \pm 0.2 \pm 0.2 $MeV, $Γ\leq$ 1 MeV, and $10.6\pm 3.7\pm3.4(br) < Γ_{\bar{p}p}B_{η_cγ} < 12.8\pm 4.8\pm4.5(br) $eV. We find no event excess within the search region in the $J/ψπ^0$ mode.
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…
We report recent results on the charmonium and charmoniumlike states based on a large data sample recorded at the $Υ(4S)$ and $Υ(5S)$ resonances with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider.
The beauty hadron decays is unique laboratory to study charmonium and charmonium-like states, such as the $χ_{c1}(3872)$ meson, other exotic states and the tensor D-wave $ψ_2(3823$) states. However the nature of many exotic charmonium-like candidates are still unknown. The most recent LHCb results related to b-hadron decays to charmonium states and obtained using large data samples collected during the Run 1 and Run 2 periods are presented. This includes the most precise determination of the mass and width of the $χ_{c1}(3872)$ state using the $B^{+} \to J/ψπ^{+}π^{-}K^{+}$ decays, observation…
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 …
At CLEO, charmonium spectroscopy is pursued both thorugh e+e- annihilation data taken in the Upsilon region and more recently at psi(2S). A nmber of first observations (eta_c', h_c, pi and K form factors) have been made, and numerous high precision measurements have been made in radiative and hadronic decays of charmonium resonances. A brief report of these contributions is presented.
BaBar and Belle have recently revived the interest in charmonium spectroscopy, discovering many unexpected resonances. In this review, I'll focus mostly on the states found in B decays and double $\ccbar$. A better understanding of their production mechanism can help to discriminate among models, confirm tentative $J^{PC}$ assignments, and clarify the overall picture.
We see copious production of charmed hadrons in the early LHCb data. The status and plans for charm production studies at LHCb are discussed, and preliminary signals are shown.
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.
The review on experimental results on charmonium and charmonium-like spectroscopy from B-factories is presented. Main theoretical interpretations, such as conventional charmonium, molecular state, hybrids, tetraquarks and others are discussed.
We review recent charmonium and bottomonium spectroscopy results from the B-factories Belle and \babar. A particular focus is given to the new $η_{c}(1S)$ and $η_{c}(2S)$ measurement and to the radiative transitions from $Υ(2S)$ and $Υ(3S)$ with converted photons.
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.
The open charm effects via intermediate hadron loop transitions seem to play a crucial role in the understanding of several existing "puzzles" in charmonium exclusive decays, such as the $ψ(3770)$ non-$D\bar{D}$ decays, and "$ρπ$ puzzle" etc. In the charmonium energy region, non-perturbative mechanisms could be still sizeable, and as a consequence the intermediate hadron loop transitions also provide a mechanism for the helicity-selection-rule (HSR) violation. We report our recent progress on those existing puzzles.
The Belle II experiment at the SuperKEKB energy-asymmetric $e^+e^-$ collider is an upgrade of the B factory facility at KEK in Tsukuba, Japan. The experiment began operation in 2019 and aims to record a factor of 50 times more data than its predecessor. Belle II is uniquely capable of studying the so-called "XYZ" particles: heavy exotic hadrons consisting of more than three quarks. First discovered by Belle, these now number in the dozens, and represent the emergence of a new category within quantum chromodynamics. We present recent results obtained from Belle II data, and the future prospects…
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…
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.
We have performed a systematic study of J/$ψ$ and $ψ$(2S) production in p--p collisions at different Large Hadron Collider (LHC) energies and at different rapidities using the leading order non-relativistic quantum chromodynamics model of heavy quarkonium production. We have included the contributions from hiher excited states decaying to J$ψ$ . The calculated values have been compared with the available data from the four experiments at LHC, namely ALICE, ATLAS, CMS and LHCb. In the case of ALICE, inclusive J/$ψ$ and $ψ$(2S) cross-sections have been calculated by including the feed-down from …
We investigate the inclusive production of prompt J/psi mesons in polarized hadron-hadron, photon-hadron, and photon-photon collisions in the factorization formalism of nonrelativistic quantum chromodynamics (NRQCD) providing all contributing partonic cross sections in analytic form. In the case of photoproduction, we also include the resolved-photon contributions. We present numerical results appropriate for BNL RHIC-Spin, the approved SLAC fixed-target experiment E161, and the e^+e^- and gamma gamma modes of TESLA. Specifically, we assess the feasibility to access the spin-dependent parton d…
We present a method for the measurement of parameters of elastic and inelastic interactions of charmonium with hadrons. In this technique, we use femtoscopic analysis of charmonium-hadron correlations at low relative momentum and the Lednicky-Lyuboshitz analytical model to extract the interaction parameters. We argue that such a study is already feasible in the LHCb experiment at the LHC, and we discuss the prospects for studies in the STAR at RHIC and other experiments at the LHC.
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.
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.
We suggest the ratio of the $ψ''(3770)/ψ'(3686)$ production cross sections as an unambiguous probe of the dominance of hard, point-like physics in charmonium production. If hard physics dominates the charmonium production the ratio : ${σ(ψ'')\overσ(ψ')}\approx {Γ(ψ''\to l^+l^-)\over Γ(ψ'\to l^+l^-)} \approx 0.1$ is independent of the process. We argue that since the dominant $D\bar D$ decay mode of the $ψ''$-meson can be detected with a high efficiency at the current facilities the effective counting rate for the $ψ''$ production should be comparable to that of the $ψ'$ and hence it could be o…
The spectrum of hadrons is important for understanding the confinement of quantum chromodynamics. Many new puzzles arose since 2003 due to the abundance of experimental discoveries with the $XYZ$ structures in the heavy quarkonium mass region being the outstanding examples. Hadronic resonances correspond to poles of the $S$-matrix, which has other types of singularities such as the triangle singularity due to the simultaneous on-shellness of three intermediate particles. Here we briefly discuss a few possible manifestations of triangle singularities in the $XYZ$ physics, paying particular atte…
