Using a data sample of 24.5 million psi(2S) the reactions psi(2S)->gamma chi_cJ, chi_cJ->gamma gamma have been studied for the first time to determine the two-photon widths of the chi_cJ states of charmonium in their decay into two photons. The measured quantities are B(psi(2S)->gamma chi_c0)xB(chi_c0->gamma gamma)=(2.22+-0.32+-0.10)x10^-5, and B(psi(2S)->gamma chi_c2)xB(chi_c2->gamma gamma)=(2.70+-0.28+-0.15)x10^-5. Using values for B(psi(2S)->gamma chi_c0,c2) and Γ(chi_c0,c2) from the literature the two-photon widths are derived to be Γ_{gamma gamma}(chi_c0)=(2.53+-0.37+-0.26) keV, Γ_{gamma gamma}(chi_c2)=(0.60+-0.06+-0.06) keV, and R=Γ_{gamma gamma}(chi_c2)/Γ_{gamma gamma}(chi_c0)= 0.237+-0.043+-0.034. The importance of the measurement of R is emphasized. For the forbidden transition, chi_c1->gamma gamma, an upper limit of Γ_{gamma gamma}(chi_c1)<0.03 keV is established.
New results of the Belle experiment at the KEKB asymmetric e^+e^- collider are presented, in particular (a) measurement of the mass and width of the $η_c$ and $η_c'$ in B meson decays, (b) measurement of the mass, width and quantum numbers of the X(3872) and (c) observation of the $χ_{c2}$ in $B$ meson decays.
Fermilab experiment E835 has done an extensive set of studies on charmonium triplet P states. The most precise measurements on mass and total width come indeed from charmonium spectroscopy by direct formation of $c\bar{c}$ states in $\bar{p}p$ annihilations. Results on both partial widths and higher multipoles radiative transitions $χ_{cJ} \to J/ψγ\to γe^+ e^-$ are given, together with the $γγ$ widths of $χ_{c0}$ and $χ_{c2}$. For the first time in hadronic charmonium production, hadronic annihilation channels ($π^0 π^0$ and $ηη$) have been clearly identified at the $χ_{c0}$ resonance.
Results are presented on Charmonium using data collected with the CLEO III and CLEO-c detectors at the Psi(2S) and Psi(3770). Measurements include, the first observation of the hc(1P1) state, the electronic widths of the J/Psi and Psi(2S), the two photon width of the Chic2 and hadronic decays of the Psi(2S).
Using the CLEO-II detector at the CESR $e^+e^-$ storage ring running at the center-of-mass energy around 10.6 GeV, we have studied exclusive production of charmonium states in two-photon collisions. Employing a dataset comprising 3.0 ${\rm fb}^{-1}$ we have searched for decays of the $η_c$, $χ_{c0}$ and $χ_{c2}$ mesons resulting in four charged hadrons. We report on the measurements of the cross sections and two-photon widths of these charmonium states.
Recent results from the CLEO experiment on decays and partial widths of various bottomonium and charmonium resonances are presented. New measurements of the di-electron partial widths for the 3 bound-state Upsilons and the J/psi are discussed. A determination of the total hadronic cross section for the psi(3770) is made, which solves a 20-year-old puzzle. The Y(4260) state is confirmed and its decay into 2 new modes is measured.
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.
We reconstruct the charmonium mesons J/psi, psi(2S) and chi_C1 using a sample of 8.46 x 10^6 B-anti-B events collected by the BABAR detector operating at e^+e^- center of mass energies near the Y(4S) resonance. By measuring rates relative to the branching fraction of the J/psi, we obtain preliminary inclusive B branching fractions of (0.25+/-0.02+/-0.02)% to the psi(2S) and (0.39+/-0.04+/-0.04)% to the chi_C1, and set a 90% confidence level limit of 0.24% on decays through the chi_C2.
Recent results obtained from the BES psi(2S) data are summarized, including the measurement of the branching ratio of the J/psi to leptons, B(J/psi -> l^+ l^-) = 5.87 +/- 0.04 +/- 0.09, many psi(2S) and chi_c branching ratios, information on the rho-pi puzzle, and measurements of the mass of the chi_c0, m(chi_c0) = 3414.1 +/- 0.6 +/- 0.8 MeV, and the eta_c, m(eta_c) = 2975.8 +/- 3.9 +/- 1.2 MeV.
At CLEO, the charmonium singlet states eta_c(2 1S0) and h_c(1 1P1) have been firmly identified and a long standing discrepancy for Gamma_(gamma gamma)(chi_c2) has been resolved.
Recent results on charmonia decays at BES/BEPC are reported, including the observation of psi'-->K_S K_L, psi'--> Vector + Tensor for the measurement of the relative phase between the strong and electromagnetic decays of psi' and a test of the pQCD ``12% rule'' between psi' and J/psi decays; the study of psi'--> gamma gamma J/psi for the determination of psi'--> pi^0 J/psi, eta J/psi, gamma chi_c1 and gamma chi_c2 decay branching fractions; the test of the color-octet mechanism via chi_cJ--> p \bar{p} and chi_cJ--> Λ\barΛ; and a search for the CP violating process psi' and J/psi--> K_S K_S.
The resonance parameters of the excited psi-family resonances, namely the psi(4040), psi(4160), and psi(4415), were determined by fitting the R-values measured by experiments. It is found that the previously reported leptonic partial widths of these states were merely one possible solutions among a four-fold ambiguity. By fitting the most precise experimental data on the R-values measured by the BES collaboration, this work presents all four sets of solutions. These results may affect the interpretation of the charmonium and charmonium-like states above 4GeV/c^2.
We report the results of a search for a charmonium-like state produced in the process gamma gamma --> omega J/psi in the 3.9-4.2 GeV/c^2 mass region. We observe a significant enhancement, which is well-described by a resonant shape with mass M = (3915 +/- 3 +/- 2) MeV/c^2 and total width Gamma = (17 +/- 10 +/- 3) MeV. This enhancement may be related to one or more of the three charmonium-like states so far reported in the 3.90-3.95 GeV/c^2 mass region.
We have studied the $^3P_J$ ($χ_c)$ states of charmonium in formation by antiproton-proton annihilations in experiment E835 at the Fermilab Antiproton Source. We report new measurements of the mass, width, and $B(χ_{cJ} \to \bar{p} p) \times Γ(χ_{cJ} \to J/ψ+ anything)$ for the $χ_{c1}$ and $χ_{c2}$ by means of the inclusive reaction $\bar{p}p \to χ_{cJ} \to J/ψ+ anything \to (e^{+}e^{-}) +anything $. Using the subsample of events where $χ_{cJ} \to γ+ J/ψ\to γ+ (e^{+}e^{-}) $ is fully reconstructed, we derive $B(χ_{cJ} \to \bar p p)\times Γ(χ_{cJ} \to J/ψ+ γ) $. We summarize the results of the…
We present new precision measurements of the psi(2S) total and partial widths from excitation curves obtained in antiproton-proton annihilations by Fermilab experiment E835 at the Antiproton Accumulator in the year 2000. A new technique of complementary scans was developed to study narrow resonances with stochastically cooled antiproton beams. The technique relies on precise revolution-frequency and orbit-length measurements, while making the analysis of the excitation curve almost independent of machine lattice parameters. We study the psi(2S) meson through the processes pbar p -> e+ e- and p…
In this talk, we present the recent results on charmonium decays from the BES experiment at the BEPC collider. The analyses are based on a 14 million psi(2S) events data sample. We report results on leptonic decays, hadronic decays, and radiative decays of psi(2S), as well as hadronic decays of chi_cJ states and rare or forbidden decays of J/psi.
The cross sections for e+e- to pi+pi-J/psi, pi+pi-psi(2S), K+K-J/psi, DDbar, DDbar pi, D*Dbar, and D*D*bar are measured using data sample collected on or near the Upsilon(4S) resonance with the Belle detector at KEKB. A peak near 4.25 GeV/c^2, corresponding to the so called Y(4260), is observed in pi+pi-J/psi final state. In addition, there is another cluster of events at around 4.05 GeV/c^2. Two resonant structures are observed in the pi+pi-psi(2S) invariant mass distribution, one at 4361+-9+-9 MeV/c^2 with a width of 74+-15+-10 MeV/c^2, and another at 4664+-11+-5 MeV/c^2 with a width of 48+-…
Experimental measurements of decay branching fractions of semitaunic and semimuonic $B_c$ into $J/ψ$ has challenged the lepton flavor universality in standard model with about two standard deviations. In this paper, we first investigate the unitary constraint on form factors of $B_c$ meson into $S$-wave and $P$-wave charmonium. Such constraint leads to the exploration of the $R_{J/ψ}$ and other ratios $R_{η_c}$, $R_{h_c}$, and $R_{χ_{cJ}}$ in a model-independent way. These results together with future experimental measurements can be used to explore the lepton flavor universality in a more sys…
Using substantially larger data samples collected by the CLEO III detector, we report on new measurements of the decays of Upsilon(1S) to charmonium final states, including J/Psi, psi(2S), and chi_cJ. The latter two are first observations of these decays. We measure the branching fractions as follows: B(Y(1S)--> J/Psi+X)=(6.4+-0.4+-0.6)x10^-4, B(Y(1S)--> psi(2S)+X)/B(Y(1S)--> J/Psi+X)=0.41+-0.11+-0.08, B(Y(1S)--> chi_c1+X)/B(Y(1S)--> J/Psi+X)=0.35+-0.08+-0.06, B(Y(1S)--> chi_c2+X)/B(Y(1S)--> J/Psi+X)=0.52+-0.12+-0.09, and B(Y(1S)--> chi_c0+X)/B(Y(1S)--> J/Psi+X)<7.4% at 90% confidence level. W…
We report measurements of charmonium resonances (J/Psi, Psi(2S),Chi_c1) using about 25 fb^-1 of data collected by the BABAR detector around the Upsilon(4S) resonance. We present measurements of inclusive charmonium production of charmonium in B decays and from the continuum, as well as exclusive branching ratios of B mesons into charmonium final states. We present also a measurement of the B0 -> K*0 gamma branching ratio and a search for the decay B0 -> gamma gamma.
The di-electron widths of $ψ(4040)$, $ψ(4160)$, and $ψ(4415)$, and their ratios are shown to be in good agreement with experiment, if in all cases the $S-D$ mixing with a large mixing angle $θ\approx 34^\circ$ is taken. Arguments are presented why continuum states give small contributions to the wave functions at the origin. We find that the Y(4360) resonance, considered as a pure $3 {}^3D_1$ state, would have very small di-electron width, $Γ_{ee}(Y(4360))=0.060$ keV. On the contrary, for large mixing between the $4 {}^3S_1$ and $3 {}^3D_1$ states with the mixing angle $θ=34.8^\circ$, $Γ_{ee}(…
In the present work, we study the OZI-allowed three body open flavor decay properties of higher vector charmonium and bottomonium states with an extended quark pair creation model. For the bottomonium system, we get that (i) the $BBπ$ and $B^*B^*π$ partial decay widths of the $Υ(5S)$ state are consistent with the experiment, and the $BB^*π$ partial decay width of the $Υ(5S)$ state is smaller but very close to the Belle's experiment. Meanwhile, (ii) the $BB^*π$ and $B^*B^*π$ decay widths of $Υ(11020)$ can reachs $2\sim3$ MeV. In addition, (iii) for the most of higher vector charmonium states, t…
This review briefly outlines recent experimental results from the charmonium system. These include new measurements of the M1 radiative transition rates $B(ψ(1S,2S)\toγη_c(1S))$; new insights into the mass of the $η_c(1S)$; the observation of $J/ψ(1S)$ decays to three photons; new measurements of the two-photon widths of the $χ_{cJ}(1P)$; the observation of radiative decays of the $χ_{cj}(1P)$ to light quarks; a precise measurement of the $h_c(1P)$ mass; and an update on properties of the $η_c(2S)$. Each result adds piecemeal to our understanding of the strong force.
We report on exclusive decays of B mesons into final states containing charmonium using data collected with the BABAR detector at the PEP-II storage rings. The charmonium states considered here are J/psi, psi(2S), and chi_C1. Branching fractions for several exclusive final states, a measurement of the decay amplitudes for the B0 --> J/psi K* decay, and measurements of the B0 and B+ masses are presented. All of the results we present here are preliminary.
Using 22.7 million BBbar events recorded with the BABAR detector, the inclusive branching fractions for the production of J/psi, psi(2S) and Chi_c in B decays are presented. Combining the charmonium state with a K+-, K0, K*+-, K*0 or neutral pion, B decays are reconstructed exlusively and branching fractions are determined. A preliminary study is also presented fot the B --> eta_c K decay mode.
We report on a search for new resonant states in the process gamma gamma --> D Dbar. A candidate C-even charmonium state is observed in the vicinity of 3.93 GeV/c^2. The production rate and the angular distribution in the gamma gamma center-of-mass frame suggest that this state is the previously unobserved chi'_(c2), the 2^3P_2 charmonium state.
We report preliminary results on the measurement of branching fractions of exclusive decays of neutral and charged B mesons into two-body final states containing a charmonium state and a light strange meson. The charmonium mesons considered are J/psi, psi(2S) and chic_c1, and the light mesons are either K or K*. We use a sample of about 124 million BBbar events collected with the BABAR detector at the PEP-II storage ring at the Stanford Linear Accelerator Center.
The $1^1D_2 (c\bar c)$ state is the ground state of spin-singlet D-wave charmonia. Although it has not been found yet, the experimental data accumulate rapidly. This charmonium attracts more and more attention, especially when the BaBar Collaboration finds that the X(3872) particle has negative parity. In this paper we calculate the double-gamma and double-gluon annihilation processes of $^1D_2$ charmonia and bottomonia by using the instantaneous Bethe-Salpeter method. We find the relativistic corrections make the decay widths of $1^1D_2 (c\bar c)$ 2$\sim$5 times smaller than the non-relativis…
Measurements of branching fractions for nine different final states, based on a data sample of approximately 4 million psi(2S) events collected with the BESI detector at the BEPC, are reported. Using the same event sample, radiative decays of the psi (2S) into pi pi, K K-bar and eta eta final states have been measured. Cross sections for e e -> e e, hadrons, pi pi J/psi, and mu mu have been measured in the vicinity of the psi(2S) resonance using the BESII detector. The psi(2S) total width; partial widths to hadrons, pi pi J/psi and muons; and corresponding branching fractions have been determi…
Recent results from BES and CLEOc experiments on charmonium decays using J/psi, psi' and psi'' data samples collected in e+e- annihilation are reviewed, including the measurement of the relative phase between strong and electromagnetic decays of psi', the study of the ``rho pi puzzle'' in J/psi and psi' decays, and the search for the non-DDbar decays of psi''. The decays of chi_cJ produced in psi' radiative transition are also reviewed. These new results shed light on the understanding of QCD.
We report measurements of branching fractions and charge asymmetries of exclusive decays of neutral and charged B mesons into two-body final states containing a charmonium state and a light strange meson. The charmonium mesons considered are J/Psi, Psi(2S) and Chi_c1, and the light meson is either K or K*. We use a sample of about 124 million BBbar events collected with the BABAR detector at the PEP-II storage ring at the Stanford Linear Accelerator Center.
We report on a search for the production of new resonance states in the process gamma gamma-->D Dbar. A candidate C-even charmonium state is observed in the vicinity of 3.93 GeV/c^2. The production rate and the angular distribution in the gamma gamma center-of-mass frame suggest that this state is the previously unobserved chi_{c2}', the 2 ^3P_2 charmonium state.
We report a new analysis of double charmonium production in e+ e- annihilation using a data sample collected by the Belle experiment. We confirm our previous observation of the processes e+ e- -> J/psi eta_c (chi_c0, eta_c(2S)) and perform an angular analysis for these processes. Processes of the type e+ e- -> psi(2S) (c cbar)_resonant are observed for the first time. We also observe a new charmonium state - X(3940), produced in the process e+ e- -> J/psi X(3940).
Based on 14 million psi(2S) and 58 million J/psi events collected by the BESII detector, the leptonic decay of psi(2S) into $τ^+τ^-$, psi(2S) multi-body decays, chi_cJ decays, and J/psi hadronic decays are studied, and the branching fractions of these decays are reported. These results may shed light on the understanding of QCD.
We report branching fraction measurements for exclusive decays of charged and neutral B mesons into two-body final states containing a charmonium meson. We use a sample of 22.72 +/- 0.36 million B anti-B events collected between October 1999 and October 2000 with the BABAR detector at the PEP-II storage rings at the Stanford Linear Accelerator Center. The charmonium mesons considered here are J/psi, psi(2S), and chi_c1, and the light meson in the decay is either a K, K^*, or pi^0.
Since the discovery of the X(3872) in 2003 the B-factory experiments BaBar and Belle have been driving forces in the spectroscopy of new charmonium-like states. In this article the latest results on the decays X(3872) -> D0 D*0bar and X(3872) -> psi gamma, where psi stands for J/psi or psi(2S), are presented and analyses of Z(4430)+ -> psi pi+ and Z(4050/4250)+ -> chi_c1 pi+ are discussed.
Using 8.5M B-anti-B events recorded by the BABAR detector the yield of inclusive J/psi, the branching ratios of psi(2S) and chi_C1 are presented. Combining the charmonium state with either a K+,KS, K*+ or K*0 exclusive B decays are reconstructed and their branching ratios determined. Using the fully reconstructed decays, both the B0 and B+ masses and their difference is measured. Finally the contributions of CP even and odd amplitudes in the decay B to J/psi K* are determined from an angular analysis.
Using the QCD sum rules approach we study the mass and decay width of the channel $J/ψ+ ω$ for the $Y(3940)$ state. We assume that it can be described by a mixed charmonium-molecule scalar state, $(χ_{c0})-(D^\ast D^\ast)$ current, with $J^{PC} = 0^{++}$ quantum numbers. For the mixing angle $(76.0 \pm 5.0)^0$, we obtain the value $M = (3.95 \pm 0.11)$ GeV for the mass, which is in good agreement with the experimental mass of the $Y(3940)$ state. For the decay width into the channel $Y \rightarrow J/ψ+ ω$, we find the value $Γ_Y = (1.7 \pm 0.6)$ MeV, which is also compatible with the experimen…
Coupled-channel effects due to coupling of charmonia to the charmed and anticharmed mesons are of current interest in heavy quarkonium physics. However, the effects have not been unambiguously established. In this paper, a clean method is proposed in order to examine the coupled-channel effects in charmonium transitions. We show that the hindered M1 radiative transitions from the 2P to 1P charmonia are suitable for this purpose. We suggest to measure one or more of the ratios Gamma(h_c'-->chi_{cJ} gamma)/Gamma(chi_{cJ}'-->chi_{cJ} pi^0) and Gamma(chi_{cJ}'-->h_c gamma)/Gamma(chi_{cJ}'-->chi_{c…
The vector and pseudoscalar decay constants are calculated in the framework of the Field Correlator Method. Di-electron widths: $Γ_{ee}(J/ψ)=5.41$ keV, $Γ_{ee}(ψ'(3686))=2.47$ keV, $Γ_{ee}(ψ''(3770))=0.248$ keV, in good agreement with experiment, are obtained with the same coupling, $α_s=0.165$, in QCD radiative corrections. We show that the larger $α_s=0.191\pm 0.004$ is needed to reach agreement with experiment for $Γ_{γγ}(η_c)=7.22$ keV, $Γ_{γγ} (χ(^3P_0))=3.3$ keV, $Γ_{γγ}(χ(^3P_2))= 0.54$ keV, and also for $Γ(J/ψ\to 3g)=59.5$ keV, $Γ(J/ψ\to γ2g)=5.7$ keV. Meanwhile even larger $α_s=0.238$…
The recently BaBar results raise the possibility that X(3872) has negative parity. This makes people reconsider assigning X(3872) to the $1{^1D_2}(c\bar c)$ state. In this paper we give a general form of the wave function of $2^{-+}$ mesons. By solving the instantaneous Bethe-Salpeter equation, we get the mass spectrum and corresponding wave functions. We calculate electromagnetic decay widths of the first $2^{-+}$ state which we assume to be the X(3872) particle. The results are $Γ(2^{-+}(3872)\rightarrow J/ψγ) = 1.59^{+0.53}_{-0.42}$ keV, $Γ(2^{-+}(3872)\rightarrow ψ(2S)γ) = 2.87^{+1.46}_{-0…
In this work, we investigate the decay widths and the line shapes of the open-charm radiative and pionic decays of Y(4274) with the $D_s\bar{D}_{s0}(2317)$ molecular charmonium assignment. Our calculation indicates that the decay widths of $Y(4274)\to D^{+}_{s}D^{*-}_{s}γ$ and $Y(4274)\to D^+_{s}D^-_{s}π^0$ can reach up to 0.05 keV and 0.75 keV, respectively. In addition, the result of the line shape of the photon spectrum of $Y(4274)\to D_s^+ {D}_s^{*-} γ$ shows that there exists a very sharp peak near the large end point of photon energy. The line shape of the pion spectrum of $Y(4274)\to D_…
Within the framework of nonrelativistic QCD (NRQCD) factorization, we calculate the next-to-leading-order (NLO) perturbative corrections to the radiative decay $Υ\to η_c(χ_{cJ})+γ$. Both the helicity amplitudes and the helicity decay widths are obtained. It is the first computation for the processes involving both bottomonium and charmonium at two-loop accuracy. By employing the Cheng-Wu theorem, we are able to convert most of complex-valued master integrals (MIs) into real-valued MIs, which makes the numerical integration much efficient. Our results indicate the $\mathcal{O}(α_s)$ corrections…
We have fully reconstructed decays of both B0 and B- Mesons into final states containing either D, D*, D**, Psi, Psi', or Chi_{c1} mesons. This allows us to obtain new results on many physics topics including branching ratios, tests of the factorization hypothesis, color suppression, resonant substructure, and the B- - B0 mass difference.
Inspired by the recent observations of the vector charmonium-like states at BES III Collaboration and $ψ(3842)$ at LHCb Collaboration, we comb the $D$ wave charmonium state in the present work. We first evaluate the possibility of $Y(4320)$ as $ψ(3^3D_1)$ by investigating its open charm decays in quark-pair creation model and we find the width of $Y(4320)$ can be reproduced in a reasonable parameter range. Moreover, we take $ψ(3770)$, $ψ(4160)$ and $Y(4320)$ as the scale of $1D$, $2D$ and $3D$ charmonia to estimate the open charm decays of other $D$ wave charmonia. The total and partial widths…
Thermal Hilbert moment QCD sum rules are used to obtain the temperature dependence of the hadronic parameters of charmonium in the vector channel, i.e. the $J$ / $ψ$ resonance mass, coupling (leptonic decay constant), total width, and continuum threshold. The continuum threshold $s_0$, which signals the end of the resonance region and the onset of perturbative QCD (PQCD), behaves as in all other hadronic channels, i.e. it decreases with increasing temperature until it reaches the PQCD threshold $s_0 = 4 m_Q^2$, with $m_Q$ the charm quark mass, at $T\simeq 1.22 T_c$. The rest of the hadronic pa…
By analyzing existing data on pseudoscalar charmonium decays, we obtain the ratio of the branching fractions of $η_c(2S)$ and $η_c$ decays into ten different final states with light hadrons. For the first time, we test the two existing theoretical predictions of these decays, and find that the experimental data are significantly different from both of them. The lack of observation of any decay mode with higher rate in $η_c(2S)$ than in $η_c$ decays suggests very unusual decay dynamics in pseudoscalar charmonium decays to be identified. We also report the first model-independent evaluation of t…
