Observation of a Broad Structure in the ${\pi }^{+}{\pi }^{-}J/\psi$ Mass Spectrum around 4.26 GeV/$c^2$

Abstract

We study initial-state radiation events, $e^{+}{e}^{-}\to {\gamma }_{ISR}{\pi }^{+}{\pi }^{-}J/\psi$, with data collected with the BaBar detector. We observe an accumulation of events near 4.26 GeV/$c^2$ in the invariant-mass spectrum of ${\pi }^{+}{\pi }^{-}J/\psi$. Fits of the mass spectrum indicate that a broad resonance with a mass of about 4.26 GeV/$c^2$ is required to describe the observed structure. The presence of additional narrow resonances cannot be excluded. The fitted width of the broad resonance is 50 to 90 MeV/$c^2$, depending on the fit hypothesis.

7 pages, 3 postscript figues, 0 tables submitted to Physics Review Letter

References in corpus (14)

• Big Bang Nucleosynthesis (in "The Review of Particle Properties" 2004)
• Observation of a narrow charmonium-like state in exclusive B+ -> K+ pi+pi- J/psi decays
• Observation of a New Narrow Charmonium State in Exclusive B+-->K+ pi+pi- J/psi Decays
• The BABAR Detector
• Observation of the Narrow State $X(3872)\to J/\psi {\pi }^{+}{\pi }^{-}$ in $\bar{p}p$ Collisions at $\sqrt{s}=1.96 \TeV$
• Observation and Properties of the X(3872) Decaying to J/psi pi+ pi- in p-p(bar) Collisions at sqrt(s) = 1.96 TeV
• Study of the B- --> J/psi K- pi+ pi- Decay and Measurement of the B- --> X(3872) K- Branching Fraction
• Observation of a near-threshold omega-J/psi mass enhancement in exclusive B-->K omega J/psi decays
• Measurement of Double Charmonium Production in $e^{+}{e}^{-}$ Annihilations at $\sqrt{s}=10.6$ GeV
• Study of double charmonium production in e^+ e^- annihilation at \sqrt{s} ~ 10.6 GeV
• The $\epem\toπ^+π^-π^+π^-$, $K^{+}{K}^{-}{\pi }^{+}{\pi }^{-}$, and $K^{+}{K}^{-}{K}^{+}{K}^{-}$ Cross Sections at Center-of-Mass Energies 0.5--4.5 \gev Measured with Initial-State Radiation
• Production of Prompt Charmonia in $e^{+}{e}^{-}$ Annihilation at $\sqrt{s}\approx 10.6$ GeV
• Evidence of psi(3770) non-DD-bar Decay to J/psi pi+pi-
• Measurement of $J/\psi$ production in continuum $e^{+}{e}^{-}$ annihilations near $\sqrt{s}=10.6$ GeV

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• The XYZs of Charmonium at BES
• Reanalysis of the $e^{+}{e}^{-}\to (D^{\ast }{\bar{D}}^{\ast }{)}^{\pm }{\pi }^{\mp }$ reaction and the claim for the $Z_c(4025)$ resonance
• Production of hadron pairs in electron-positron annihilation near the K(+)K(-), D-Dbar, B-Bbar and Lambda(c)(+)-Lambda(c)(-) thresholds
• Observation of $e^{+}{e}^{-}\to \eta h_c$ at center-of-mass energies from 4.085 to 4.600 GeV
• Disentangling the role of the $Y(4260)$ in $e^{+}{e}^{-}\to D^{\ast }{\bar{D}}^{\ast }$ and $D_s^{\ast }{\bar{D}}_s^{\ast }$ via line shape studies
• Initial State Radiation: A success story
• Hidden-charm Hexaquarks from Lattice QCD
• Understanding the newly observed Y(4008) by Belle
• Dynamics of hadron strong production and decay
• Measurements of the branching fractions of ${\eta }_c\to K^{+}{K}^{-}{\pi }^0$, $K_S^0{K}^{\pm }{\pi }^{\mp }$,$2({\pi }^{+}{\pi }^{-}{\pi }^0)$, and $p\bar{p}$
• Search for charmonium and charmonium-like states in ${\rm Y}(1S)$ radiative decays
• The interplay between compact and molecular structures in tetraquarks
• Measurements of $e^{+}{e}^{-}\to K_S^0{K}^{\pm }{\pi }^{\mp }{\pi }^0$ and $K_S^0{K}^{\pm }{\pi }^{\mp }\eta$ at center-of-mass energies from $3.90$ to $4.60\mathrm{GeV}$
• Open charm hadron spectroscopy at B-factories
• Global coupled-channel analysis of $e^{+}{e}^{-}\to c\bar{c}$ processes in $\sqrt{s}=3.75-4.7$ GeV
• Measurement of $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{D}^{+}{D}^{-}$ cross sections at center-of-mass energies from 4.190 to 4.946 GeV
• Understanding the cross section of $e^{+}{e}^{-}\to \eta J/\psi$ process via nonrelativistic QCD
• Mapping a new cluster of charmoniumlike structures at $e^{+}{e}^{-}$ collisions
• Four-quark structure of the excited states of heavy mesons
• Charmonium spectrum with a Dirac potential model in the momentum space
• Study on possible molecular states composed of ${\Lambda }_c\bar{D}$ (${\Lambda }_{b}B$) and ${\Sigma }_c\bar{D}$ (${\Sigma }_{b}B$) within the Bethe-Salpeter framework
• Predicted $\Lambda \bar{\Lambda }$ and ${\Xi }^{-}{\bar{\Xi }}^{+}$ decay modes of the charmoniumlike $Y(4230)$
• Possible Molecular States Composed of Doubly Charmed Baryons with Couple-channel Effect
• Spectroscopy of Mesons with Heavy Quarks
• Physics Accomplishments and Future Prospects of the BES Experiments at the BEPC Collider
• Instanton effects on the heavy-quark static potential
• The recoil correction and spin-orbit force for the possible $B^{\ast }{\bar{B}}^{\ast }$ and $D^{\ast }{\bar{D}}^{\ast }$ states
• Measurement of the cross section of $e^{+}{e}^{-}\to {\Xi }^{-}{\bar{\Xi }}^{+}$ at center-of-mass energies between 3.510 and 4.843 GeV
• $Y(4626)$ in a chiral constituent quark model
• Measurement of cross sections for $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}$ at center-of-mass energies from 3.80 to 4.60 GeV
• Toward $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}$ annihilation inspired by higher $\rho$ mesonic states around 2.2 GeV
• Observation of $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}\psi (3770)$ and $D_1(2420{)}^0{\bar{D}}^0+c.c.$
• Reconciling the X(2240) with the Y(2175)
• Search for new decay modes of the ${\psi }_2(3823)$ and the process $e^{+}{e}^{-}\to {\pi }^0{\pi }^0{\psi }_2(3823)$
• Observation of $e^{+}{e}^{-}\to \varphi {\chi }_{c1}$ and $\varphi {\chi }_{c2}$ at $\sqrt{s}$=4.600 GeV
• Charmonium: Conventional and $XYZ$ States in a Relativistic Screened Potential Model
• Colloquium: Hadron Production in Open-charm Meson Pair at $e^{+}{e}^{-}$ Collider
• Evidence for $e^{+}{e}^{-}\to \gamma {\chi }_{c1,2}$ at center-of-mass energies from 4.009 to 4.360 GeV
• $Qq\bar{Q}{\bar{q}}^{\prime }$ States in Chiral SU(3) Quark Model
• Measurement of $e^{+}{e}^{-}\to \eta J/\psi$ Cross Section from $\sqrt{s}=$ 3.808 GeV to 4.951 GeV
• Cross section measurements of the $e^{+}{e}^{-}\to D^{\ast +}{D}^{\ast -}$ and $e^{+}{e}^{-}\to D^{\ast +}{D}^{-}$ processes at center-of-mass energies from 4.085 to 4.600 GeV
• Exotic Hadrons from Scattering in the Diabatic Dynamical Diquark Model
• Estimating decay rate of $X^{\pm }(5568)\to B_s{\pi }^{\pm }$ while assuming them to be molecular states
• Studying the $D_{1}D$ molecule in the Bethe-Salpeter equation approach
• Hadronic Molecular States Composed of Spin-$\frac{3}{2}$ Singly Charmed Baryons
• The electromagnetic decays of $X(3823)$ as the ${\psi }_2(1^3{D}_2)$ state and its radial excited states
• Charmonium possibility of X(3872)
• Search for the isospin violating decay $Y(4260)\to J/\psi \eta {\pi }^0$
• How higher charmonia shape the puzzling data of the $e^{+}{e}^{-}\to \eta J/\psi$ cross section
• A novel explanation of charmonium-like structure in $e^{+}{e}^{-}\to \psi (2S){\pi }^{+}{\pi }^{-}$
• Search for resonances decaying to eta_c pi+ pi- in two-photon interactions
• Spectrum of the molecular hexaquarks
• Eight very excited spectra and one possible axion in SU(3) lattice gauge theory
• $K^0\Lambda$ and $D^{-}{\Lambda }_c^{+}$ production induced by pion beams off the nucleon
• Detecting the polarization in ${\chi }_{cJ}\to \varphi \varphi$ decays to probe hadronic loop effect
• Measurement of $e^{+}{e}^{-}\to \gamma {\chi }_{c0,c1,c2}$ cross sections at center-of-mass energies between 3.77 and 4.60 GeV
• Instanton effects on charmonium states
• Probing double hadron resonances by the complex scaling method
• Evidence for $e^{+}{e}^{-}\to \gamma {\eta }_c(1S)$ at center-of-mass energies between 4.01 and 4.60 GeV
• The strong vertices of charmed mesons $D$, $D^{\ast }$ and charmonia $J/\psi$, ${\eta }_c$
• Precision measurements of ${\sigma }_B(e^{+}{e}^{-}\to K_S^0{K}^{\pm }{\pi }^{\mp })$ at center-of-mass energies between 3.8 and 4.6 GeV
• Heavy Hadron Spectroscopy
• Measurements of Born Cross Sections of $e^{+}{e}^{-}\to D_s^{\ast +}{D}_{sJ}^{-}+c.c.$
• Improved Measurement of Branching Fractions for pipi Transitions among Upsilon(nS)States
• New Studies of XYZ States at PANDA
• Measurement of the Born Cross Sections for $e^{+}{e}^{-}\to D_s^{+}{D}_{s1}(2460{)}^{-}+c.c.$ and $e^{+}{e}^{-}\to D_s^{\ast +}{D}_{s1}(2460{)}^{-}+c.c.$
• Observation of di-structures in $e^{+}{e}^{-}\to J/\psi \mathrm{X}$ at center-of-mass energies around 3.773 GeV
• Properties of $Z_c(3900)$ tetraquark in a cold nuclear matter
• QCD Exotics
• First measurement of $e^{+}{e}^{-}\to p{K}_S^0\bar{n}{K}^{-}+c.c.$ above open charm threshold
• Study of $e^{+}{e}^{-}\to D^{+}{D}^{-}{\pi }^{+}{\pi }^{-}$ at center-of-mass energies from 4.36 to 4.60 GeV
• Regge Trajectories of Exotic Hadrons in the Flux Tube Model
• Observation of $e^{+}{e}^{-}\to D_s^{+}\overline{D}{}^{(\ast )0}{K}^{-}$ and study of the $P$-wave $D_s$ mesons
• Radial Regge trajectories for higher $\psi (nS)$ and $\psi (nD)$ states
• Study of $e^{+}{e}^{-}\to 2(p\bar{p})$ at center-of-mass energies between 4.0 and 4.6 GeV
• Measurement of $e^{+}{e}^{-}\to \gamma {\chi }_{cJ}$ via initial state radiation at Belle
• Measurement of $e^{+}{e}^{-}\to \Lambda \bar{\Lambda }\eta$ from 3.5106 to 4.6988 GeV and study of $\Lambda \bar{\Lambda }$ mass threshold enhancement
• Search for $XYZ$ states in ${\rm Y}(1S)$ inclusive decays
• Measurements of $e^{+}{e}^{-}\to {\eta }_{\mathrm{c}}{\pi }^{+}{\pi }^{-}{\pi }^0$, ${\eta }_{\mathrm{c}}{\pi }^{+}{\pi }^{-}$ and ${\eta }_{\mathrm{c}}{\pi }^0\gamma$ at $\sqrt{s}$ from 4.18 to 4.60\,GeV, and search for a $Z_{\mathrm{c}}$ state close to the $D\bar{D}$ threshold decaying to ${\eta }_{\mathrm{c}}\pi$ at $\sqrt{s}$ = 4.23 GeV
• Three body open flavor decays of higher charmonium and bottomonium
• Hybrid meson masses and the correlated Gaussian basis
• $B^{(\ast )}{\bar{B}}^{(\ast )}$ intermediate state contribution to ${\rm Y}(4S,5S)\to {\eta }_b+\gamma$ radiative decay
• Perspectives and Outlook from HEP Window on the Universe
• Search for the $B\to Y(4260)K,Y(4260)\to J/\psi {\pi }^{+}{\pi }^{-}$ decays
• QCD string in excited heavy-light mesons and heavy-quark hybrids
• Systematics of fully heavy dibaryons
• Possible Molecular Explanation for the Resonance $Y(4500)$
• New Spectroscopy with PANDA at FAIR: X, Y, Z and the F-wave Charmonium States
• How can $X^{\pm }(5568)$ escape detection?
• Gluonic Hidden-charm Tetraquark States
• Observation of B${}^0$ $\to$ $\psi$(2S)K${}_{\mathrm{S}}^0{\pi }^{+}{\pi }^{-}$ and B${}_{\mathrm{S}}^0$ $\to$ $\psi$(2S)K${}_{\mathrm{S}}^0$ decays
• Gluons, Light and Heavy Quarks in the Instanton Vacuum
• Systematic study of pentaquark states: $qqq-q\bar{q}$ configuration
• Resonance parameters of the vector charmoniumlike state $G(3900)$
• Hyperspherical-coordinate approach to the spectra and decay widths of hybrid quarkonia
• Search for B+ -> J/psi eta' K+ and B0 -> J/psi eta' Ks0 Decays
• Study of $e^{+}{e}^{-}\to \eta \varphi$ via Initial State Radiation at Belle
• The unquenched quark model
• First Observation of a Three-Resonance Structure in $e^{+}{e}^{-}\to$Nonopen Charm Hadrons
• Reevaluating the $\psi (4160)$ Resonance Parameter Using $B^{+}\to K^{+}{\mu }^{+}{\mu }^{-}$ Data in the Context of Unquenched Charmonium Spectroscopy
• The ground states and first radial excitations of the vector tetraquark states with explicit P-waves via the QCD sum rules
• Two-Loop QCD Renormalization and Anomalous Dimension of the Scalar Diquark Operator
• The XYZ mesons: what they aren't
• The spectrum of charmonium in the Resonance-Spectrum Expansion
• A study of meson-meson potential in the chiral quark model
• Heavy Quarkonium Physics from Effective Field Theories
• Charmonium production in e+e- to ψ+ X(c\bar c) and e+e- to D*D_J
• Cross section measurements of $e^{+}{e}^{-}\to \Phi K^{+}{K}^{-}$ and $e^{+}{e}^{-}\to \Phi K_S^0{K}_S^0$ at center-of-mass energies between 3.7730 GeV and 4.7008 GeV
• Light meson emissions of the selected charmonium-like states within compact tetraquark configurations
• Recent BES Results on Hadron Spectroscopy
• Investigating different structures for the $X(3872)$
• Schottky Anomaly and Hadronic Spectrum
• Towards Meson Spectroscopy Instead of Bump Hunting
• Masses and decays of the bottom-charm hybrid meson $c\bar{b}g$
• Cross sections of e+e- --> gamma VV and e+e- --> gamma gamma V
• R-Matrix Calculations for Few-Quark Bound States
• Analysis of bound and resonant states of doubly heavy tetraquarks with spin $J\le 2$
• The possible $B\pi$ molecular state and its radiative decay
• Towards a Theoretical Understanding of the XYZ Mesons from QCD
• Measurement of Born cross section of $e^{+}{e}^{-}\to {\Sigma }^0{\bar{\Sigma }}^0$ at $\sqrt{s}=3.50-4.95$ GeV
• Exotic c c-bar Mesons
• New charmonium-like states
• B Factories
• Cross section measurement of $e^{+}{e}^{-}\to \eta \psi (2S)$ and search for $e^{+}{e}^{-}\to \eta \tilde{X}(3872)$
• Search for $\psi (4S)\to \eta J/\psi$ in $B^\pm \ra ηJ/ψK^\pm$ and $e^{+}{e}^{-}\to \eta J/\psi$ processes
• Hadronic Physics and Exotics
• Coupled-channel study of $4S$-$3D$ mixing dynamics in $\psi (4220)$ and $\psi (4380)$
• Search for the reaction $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{\chi }_{cJ}$ and a charmonium-like structure decaying to ${\chi }_{cJ}{\pi }^{\pm }$ between 4.18 and 4.60 GeV
• Three-body strong decays of the $Y(4230)$ via the light-cone QCD sum rules
• PHOKHARA, the radiative return and the $(g-2{)}_{\mu }$ puzzle
• Correction to the energy spectrum of ${}^1{S}_0$ heavy quarkonia due to two-gluon annihilation effect
• Search for light tetraquark states in ${\rm Y}(1S)$ and ${\rm Y}(2S)$ decays
• $D$ wave charmonia
• Measurement of $e^{+}{e}^{-}\to \varphi {\eta }^{\prime }$ cross sections at center-of-mass energies between 3.508 and 4.600 GeV
• Doubly-charmed pentaquark states in a mass splitting model
• Light hadron, Charmonium(-like) and Bottomonium(-like) states
• Looking for a vector charmonium-like state $Y$ in $e^{+}{e}^{-}\to \bar{D}{D}_1(2420)+c.c.$
• Baryons and baryoniums in the perspective of QCD sum rules
• Hadron and Quarkmonium Exotica
• Prospects for observing the missing $2D$ and $1F$ charmonium states around 4 GeV
• Line-shape analysis of charmonium resonances
• Hidden and open charm at Belle (and elsewhere)
• Charm and Charmonium Spectroscopy
• Improved description of e^+e^- \to p\bar{p}π^0 cross section line shape and more stringent constraints on ψ(3770) and ψ(4230) \to p\bar{p}π^0
• Photo- and Electron-Production of Mesons on Nucleons and Nuclei
• Heavy Quarkonium Spectroscopy
• Observation of the first iso-spin Charmonium-like State $Z_c(4020)$ }
• Search for $e^{+}{e}^{-}\to \varphi {\chi }_{c0}$ and $\varphi {\eta }_{c2}(1D)$ at center-of-mass energies from 4.47 to 4.95 GeV
• The Physics of Charm: Recent Experimental Results
• Searches for, and Properties of, New Charmonium-like States
• Recent results from Lattice QCD
• Meson scattering and tetraquarks in two-dimensional QCD
• Pinpointing Physical Solutions in Y(4230) Decays
• Systematic study of exotic $1^{-+}$ tetraquark spectroscopy
• Search for the $Y(2175)$ in the photoproduction cross section measurement of $\gamma p\to \varphi {\pi }^{+}{\pi }^{-}p$ at GlueX
• Exotic hadrons associated with $b$-quark
• Charm cross-section and charmonium(like) states in e+e- annihilation with Belle
• X, Y and Z States
• Cross section measurement of $e^{+}{e}^{-}\to {\pi }^0{\pi }^0\psi (3686)$ from $\sqrt{s}=$ 4.008 GeV to 4.951 GeV
• 16th International Conference in Quantum ChromoDynamics: Charmonium-like states at BaBar
• Recent Results on Charmonium Decays at CLEO-c
• Possible ${\bar{D}}^{(\ast )}{\Xi }_{cc}^{(\ast )}$ and ${\Xi }_{cc}^{(\ast )}{\Xi }_{cc}^{(\ast )}$ molecules as superflavor partners of $T_{cc}$
• Mass-Spectroscopy of [$bb][\bar{b}\bar{b}$] and [$bq][\bar{b}\bar{q}$] tetraquark states in a diquark-antidiquark formalism
• X, Y, Z Search at Belle II
• The SuperB Physics Programme
• Summary of Experimental Meson Physics
• Study of $e^{+}{e}^{-}\to h^{+}{h}^{-}J/\psi (h=\pi ,K,p)$ via initial-state radiation at Belle~II
• Signatures of Exotic Hadrons