Using 13.3 fb^-1 of e+e- collision data taken in the Upsilon(1S-4S) region
with the CLEO III detector at the CESR collider, a search has been made for the
new resonance Y(4260) recently reported by the BaBar Collaboration. The
production of Y(4260) in initial state radiation (ISR), and its decay into
pi+pi-J/psi are confirmed. A good quality fit to our data is obtained with a
single resonance. We determine M(Y(4260))=(4284+17-16(stat)+-4(syst)) MeV/c^2,
Gamma(Y(4260))=(73+39-25(stat)+-5(syst)) MeV/c^2, and
Gamma_ee(Y(4260))xBr(Y(4260)->pi+pi-J/psi)=(8.9+3.9-3.1(stat)+-1.9(syst))
eV/c^2.Comment: 8 pages postscript,also available through
  http://www.lns.cornell.edu/public/CLNS/2006/, Submitted to PRD (Rapid Comm.

A. J. Sadoff

A. Lincoln

A. Lopez

A. Ryd

A. Smith

A. Tomaradze

A. W. Scott

B. I. Eisenstein

B. Sanghi

B. W. Lang

B. Xin

C. Cawlfield

C. D. Jones

C. S. Park

C. Sedlack

D. Besson

D. Cinabro

D. Cronin-Hennessy

D. G. Cassel

D. H. Miller

D. Hertz

D. Kim

D. L. Hartill

D. L. Kreinick

D. M. Asner

D. Peterson

D. Riley

E. H. Thorndike

E. J. White

E. A. Kuraev

F. Yang

G. Bonvicini

G. S. Adams

G. S. Huang

G. Tatishvili

H. Mahlke-Krüger

H. Mendez

H. Muramatsu

H. Schwarthoff

H. Severini

H. Vogel

I. Danko

I. Karliner

I. P. J. Shipsey

J. Butt

J. C. Wang

J. Chen

J. E. Duboscq

J. Ernst

J. Hietala

J. Insler

J. Kandaswamy

J. L. Rosner

J. Li

J. Napolitano

J. P. Alexander

J. P. Cummings

J. Pivarski

J. R. Patterson

J. Ramirez

J. Wiss

J. Yelton

K. Berkelman

K. K. Seth

K. M. Ecklund

K. Randrianarivony

K. W. Edwards

K. Y. Gao

K. Zhang

L. Fields

L. Gibbons

M. Anderson

M. Artuso

M. Dubrovin

M. E. Watkins

M. R. Shepherd

M. Selen

M. Weinberger

N. E. Adam

N. Lowrey

N. Menaa

O. Aquines

P. Naik

P. Rubin

P. U. E. Onyisi

P. Zweber

Q. He

R. A. Briere

R. E. Mitchell

R. Ehrlich

R. Gray

R. Mountain

R. Patel

R. Poling

R. S. Galik

R. Sia

S. A. Dytman

S. B. Athar

S. Blusk

English

arXiv

T. E. Coan

Y. S. Gao

S. Nisar

T. Skwarnicki

S. Stone

S. E. Csorna

T. Ferguson

S. W. Gray

V. E. Kuznetsov

X. Shi

S. Stroiney

W. M. Sun

T. Wilksen

V. Potlia

T. K. Pedlar

Y. Kubota

T. Klein

S. Dobbs

Z. Metreveli

Crossref

Confirmation of the
                    
                      Y

Using 13.3 fb(-1) of e(+)e(-) collision data taken in the Upsilon(1S-4S) region with                 the CLEO III detector at the CESR collider, a search has been made for the new                 resonance Y(4260) recently reported by the BABAR Collaboration. The production of                 Y(4260) in initial state radiation (ISR), and its decay into pi(+)pi(-)J/psi, are                 confirmed. A good quality fit to our data is obtained with a single resonance. We                 determine M(Y(4260))=(4284(-16)(+17)(stat)+/- 4(syst)) MeV/c(2),                 Gamma(Y(4260))=(73(-25)(+39)(stat)+/- 5(syst)) MeV/c(2), and                 Gamma(ee)(Y(4260))xB(Y(4260)-\u3epi(+)pi(-)J/psi)=(8.9(-3.1)(+3.9)(stat)+/-                 1.8(syst)) eV/c(2)

He, Q.

Insler, J.

Muramatsu, H.

Park, C. S.

Thorndike, E. H.

Yang, F.

Coan, T. E.

Gao, Y. S.

Artuso, M.

Blusk, S.

Butt, J.

Li, J.

Menaa, N.

Mountain, R.

Nisar, S.

Randrianarivony, K.

Sia, R.

Skwarnicki, T.

Stone, S.

Wang, J. C.

Zhang, K.

Csorna, S. E.

Bonvicini, G.

Cinabro, D.

Dubrovin, M.

Lincoln, A.

Asner, D. M.

Edwards, K. W.

Briere, R. A.

Chen, J.

Ferguson, T.

Tatishvili, G.

Vogel, H.

Watkins, M. E.

Rosner, J. L.

Adam, N. E.

Alexander, J. P.

Berkelman, K.

Cassel, D. G.

Duboscq, J. E.

Ecklund, K. M.

Ehrlich, R.

Fields, L.

Galik, R. S.

Gibbons, L.

Gray, R.

Gray, S. W.

Hartill, D. L.

Hertz, D.

Jones, C. D.

Kandaswamy, J.

Kreinick, D. L.

Kuznetsov, V. E.

Mahlke-Kruger, H.

Onyisi, P. U. E.

Patterson, J. R.

Peterson, D.

Pivarski, J.

Riley, D.

Ryd, A.

Sadoff, A. J.

Schwarthoff, H.

Shi, X.

Stroiney, S.

Sun, W. M.

Wilksen, T.

Weinberger, M.

Athar, S. B.

Patel, R.

Potlia, V.

Yelton, J.

Rubin, P.

Cawlfield, C.

Eisenstein, B. I.

Karliner, I.

Kim, D.

Lowrey, N.

PhysicsPhysics Research PublicationsPurdue University Year Confirmation of the Y(4260) resonanceproduction in initial state radiationQ. He, J. Insler, H. Muramatsu, C. S. Park, E. H. Thorndike, F. Yang, T. E.Coan, Y. S. Gao, M. Artuso, S. Blusk, J. Butt, J. Li, N. Menaa, R. Mountain,S. Nisar, K. Randrianarivony, R. Sia, T. Skwarnicki, S. Stone, J. C. Wang, K.Zhang, S. E. Csorna, G. Bonvicini, D. Cinabro, M. Dubrovin, A. Lincoln, D.M. Asner, K. W. Edwards, R. A. Briere, J. Chen, T. Ferguson, G. Tatishvili, H.Vogel, M. E. Watkins, J. L. Rosner, N. E. Adam, J. P. Alexander, K. Berkelman,D. G. Cassel, J. E. Duboscq, K. M. Ecklund, R. Ehrlich, L. Fields, R. S. Galik,L. Gibbons, R. Gray, S. W. Gray, D. L. Hartill, D. Hertz, C. D. Jones, J.Kandaswamy, D. L. Kreinick, V. E. Kuznetsov, H. Mahlke-Kruger, P. U. E.Onyisi, J. R. Patterson, D. Peterson, J. Pivarski, D. Riley, A. Ryd, A. J. Sadoff,H. Schwarthoff, X. Shi, S. Stroiney, W. M. Sun, T. Wilksen, M. Weinberger, S.B. Athar, R. Patel, V. Potlia, J. Yelton, P. Rubin, C. Cawlfield, B. I. Eisenstein,I. Karliner, D. Kim, N. Lowrey, P. Naik, C. Sedlack, M. Selen, E. J. White, J.Wiss, R. E. Mitchell, M. R. Shepherd, D. Besson, T. K. Pedlar, D. Cronin-Hennessy, K. Y. Gao, J. Hietala, Y. Kubota, T. Klein, B. W. Lang, R. Poling,A. W. Scott, A. Smith, P. Zweber, S. Dobbs, Z. Metreveli, K. K. Seth, A.Tomaradze, J. Ernst, H. Severini, S. A. Dytman, W. Love, V. Savinov, O.Aquines, Z. Li, A. Lopez, S. Mehrabyan, H. Mendez, J. Ramirez, G. S. Huang,D. H. Miller, V. Pavlunin, B. Sanghi, I. P. J. Shipsey, B. Xin, G. S. Adams, M.Anderson, J. P. Cummings, I. Danko, and J. NapolitanoThis paper is posted at Purdue e-Pubs.http://docs.lib.purdue.edu/physics articles/264Confirmation of the Y4260 resonance production in initial state radiationQ. He,1 J. Insler,1 H. Muramatsu,1 C. S. Park,1 E. H. Thorndike,1 F. Yang,1 T. E. Coan,2 Y. S. Gao,2 M. Artuso,3 S. Blusk,3J. Butt,3 J. Li,3 N. Menaa,3 R. Mountain,3 S. Nisar,3 K. Randrianarivony,3 R. Sia,3 T. Skwarnicki,3 S. Stone,3 J. C. Wang,3K. Zhang,3 S. E. Csorna,4 G. Bonvicini,5 D. Cinabro,5 M. Dubrovin,5 A. Lincoln,5 D. M. Asner,6 K. W. Edwards,6R. A. Briere,7 J. Chen,7 T. Ferguson,7 G. Tatishvili,7 H. Vogel,7 M. E. Watkins,7 J. L. Rosner,8 N. E. Adam,9J. P. Alexander,9 K. Berkelman,9 D. G. Cassel,9 J. E. Duboscq,9 K. M. Ecklund,9 R. Ehrlich,9 L. Fields,9 R. S. Galik,9L. Gibbons,9 R. Gray,9 S. W. Gray,9 D. L. Hartill,9 D. Hertz,9 C. D. Jones,9 J. Kandaswamy,9 D. L. Kreinick,9V. E. Kuznetsov,9 H. Mahlke-Krüger,9 P. U. E. Onyisi,9 J. R. Patterson,9 D. Peterson,9 J. Pivarski,9 D. Riley,9 A. Ryd,9A. J. Sadoff,9 H. Schwarthoff,9 X. Shi,9 S. Stroiney,9 W. M. Sun,9 T. Wilksen,9 M. Weinberger,9 S. B. Athar,10 R. Patel,10V. Potlia,10 J. Yelton,10 P. Rubin,11 C. Cawlfield,12 B. I. Eisenstein,12 I. Karliner,12 D. Kim,12 N. Lowrey,12 P. Naik,12C. Sedlack,12 M. Selen,12 E. J. White,12 J. Wiss,12 R. E. Mitchell,13 M. R. Shepherd,13 D. Besson,14 T. K. Pedlar,15D. Cronin-Hennessy,16 K. Y. Gao,16 J. Hietala,16 Y. Kubota,16 T. Klein,16 B. W. Lang,16 R. Poling,16 A. W. Scott,16A. Smith,16 P. Zweber,16 S. Dobbs,17 Z. Metreveli,17 K. K. Seth,17 A. Tomaradze,17 J. Ernst,18 H. Severini,19S. A. Dytman,20 W. Love,20 V. Savinov,20 O. Aquines,21 Z. Li,21 A. Lopez,21 S. Mehrabyan,21 H. Mendez,21 J. Ramirez,21G. S. Huang,22 D. H. Miller,22 V. Pavlunin,22 B. Sanghi,22 I. P. J. Shipsey,22 B. Xin,22 G. S. Adams,23 M. Anderson,23J. P. Cummings,23 I. Danko,23 and J. Napolitano23(CLEO Collaboration)1University of Rochester, Rochester, New York 14627, USA2Southern Methodist University, Dallas, Texas 75275, USA3Syracuse University, Syracuse, New York 13244, USA4Vanderbilt University, Nashville, Tennessee 37235, USA5Wayne State University, Detroit, Michigan 48202, USA6Carleton University, Ottawa, Ontario, Canada K1S 5B67Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA8Enrico Fermi Institute, University of Chicago, Chicago, Illinois 60637, USA9Cornell University, Ithaca, New York 1485310University of Florida, Gainesville, Florida 32611, USA11George Mason University, Fairfax, Virginia 22030, USA12University of Illinois, Urbana-Champaign, Illinois 61801, USA13Indiana University, Bloomington, Indiana 47405, USA14University of Kansas, Lawrence, Kansas 66045, USA15Luther College, Decorah, Iowa 52101, USA16University of Minnesota, Minneapolis, Minnesota 55455, USA17Northwestern University, Evanston, Illinois 60208, USA18State University of New York at Albany, Albany, New York 12222, USA19University of Oklahoma, Norman, Oklahoma 73019, USA20University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA21University of Puerto Rico, Mayaguez, Puerto Rico 0068122Purdue University, West Lafayette, Indiana 47907, USA23Rensselaer Polytechnic Institute, Troy, New York 12180, USA(Received 25 October 2006; published 20 November 2006)Using 13:3 fb1 of ee collision data taken in the 1S 4S region with the CLEO III detector atthe CESR collider, a search has been made for the new resonance Y4260 recently reported by the BABARCollaboration. The production of Y4260 in initial state radiation (ISR), and its decay into J= , areconfirmed. A good quality fit to our data is obtained with a single resonance. We determine MY4260 42841716stat  4syst MeV=c2, Y4260  733925stat  5syst MeV=c2, and eeY4260 BY4260 ! J=   8:93:93:1stat  1:8syst eV=c2.DOI: 10.1103/PhysRevD.74.091104 PACS numbers: 14.40.Gx, 13.25.Gv, 13.66.BcThe BABAR Collaboration [1] has reported the observa-tion of a broad structure in the J= mass spectrumaround 4:26 GeV=c2 in initial state radiation (ISR) events,ee ! ISRJ= . Data with a total luminosity of233 fb1 were taken at and near the peak of the 4Sresonance. The enhancement, labeled Y4260, was fittedPHYSICAL REVIEW D 74, 091104(R) (2006)RAPID COMMUNICATIONS1550-7998=2006=74(9)=091104(5) 091104-1 © 2006 The American Physical Societyas a single resonance with a signal/background ratio ofapproximately 2=1, number of events NY  125 13,mass MY  4259 8stat26syst MeV=c2, widthY  88 23stat64syst MeV=c2, and eeY BY ! J=   5:5 1:0stat0:80:7syst eV=c2.The observation of Y4260 in ISR leads to the conclusionthat it is a vector with JPC  1, with additional evidenceprovided by the observation that the dipion mass spectrumpeaks at high mass, consistent with a S-wave phase spacemodel. Recently, BABAR has reported that no evidence forY4260 excitation is found in the reaction ee !ISRp p, and obtained a ratio which is equivalent to a90% confidence limit of eeY BY ! p p<0:72 eV=c2 [2]. In the reaction B ! J= K theyreport a 3:1 resonance signal and establish a 95% con-fidence limit of B ! YK BY ! J= <255 eV=c2 [3]. None of the theoretical calculations ofcharmonium spectra predict a vector state near4260 MeV=c2, and the measurements of the parameterR  hadrons= actually show a dip in thisregion, which is quite well fitted with the known charmo-nium vectors [4]. These facts make Y4260 an unexpectedand provocative resonance, and many theoretical modelshave been proposed to explain its nature [5,6]. This alsomakes it extremely important to make an independentexperimental confirmation of the Y4260 resonance andits parameters. This paper reports on just such aconfirmation.In a recent measurement of direct ee annihilation atsp 4040, 4160, and 4260 MeV=c2, CLEO [7] has con-firmed the existence of an enhancement in the J= cross section at 4260 MeV=c2 by measuring a cross sec-tion consistent with the peak cross section reported byBABAR. Similar enhancements were observed in00J= and KKJ= . However, because the near-peak Y4260 data were limited to a single energy point,the mass and width of Y4260 could not be determined. Inthis paper, we present the results of the ISR production ofY4260 in 13:3 fb1 of ee data taken in the 1S–4Sregion with the CLEO detector at CESR, the ee colliderat Cornell University. Although our integrated luminosityis considerably less than that used by BABAR, the lowbackground in our measurement enables us to make astatistically significant confirmation of Y4260, and anindependent determination of its mass and width.The data used in the present investigations consist of1.40, 1.77, 1.60, and 8:57 fb1 taken at and in the vicinityof the 1S, 2S, 3S, and 4S resonances, re-spectively. The CLEO detector in its CLEO III [8] con-figuration was used to detect final state particles. Thereaction studied was ee ! ISRJ= ; J= ! ee; :The four charged particles in the final state,  andll, were detected. It was required that both electrons, orat least one muon be identified in the barrel or end capregions of the detector. The energy E deposited in thecalorimeter, and the momentum p measured by the track-ing chamber, were used to form E=p. It was required thatfor electrons 0:85<E=p< 1:1, and for muons E=p< 0:3.Electron candidates were required to have specific ioniza-tion energy loss, dE=dx, in the drift chamber consistentwith the electron hypothesis within 3. For muons apenetration depth of 	 3 hadronic interaction lengths inthe muon chambers was required. Pions were identifiedusing both the dE=dx information from the drift chamberand the information from the Ring Imaging Cherenkov(RICH) detector. The four charged particles were requiredto have net charge equal to zero. Further, very looserequirements were used, namely, total energy <6:5 GeV,total transverse momentum, pT < 3:5 GeV=c, and totalenergy of showers not matched with charged particles,Eneut < 5 GeV. Lepton pairs were accepted in the rangejMll MJ= j  50 MeV=c2. The event selectioncriteria were optimized by using GEANT-based [9]Y4260 ISR signal Monte Carlo and J= side band yieldas background, to maximize S2=S B, where S and Brefer to the signal and background event counts, respec-tively. The sideband was defined as 2.7 to 3:5 GeV=c2,excluding the region 2.9 to 3:2 GeV=c2.The ISR events were identified by constructing the massof the missing particle as M2miss  2Ebeam  EJ= 2  pJ= 2:The resulting M2miss distributions are shown in Fig. 1. Thepeaks centered at M2miss  0 correspond to the missing ISRphoton and have little background under them. Above thepeak in the spectrum for J= ! ~~, the backgroundincreases rapidly because of misidentified pions. We con-sider events with jM2missj< 1:7 GeV2=c4 for J= ! ee,and events with jM2missj< 1:0 GeV2=c4 for J= !~~, as ISR events. In order to improve the massresolution, these events were fitted with the lepton tracksconstrained to a common vertex, and the dilepton massconstrained to the J= mass, 3097 MeV=c2. The distribu-tions for the 2 of the vertex and J= mass constraints,lepton and pion momenta, transverse momentum, andneutral energy for these selected events were found to bein good agreement with the corresponding distributions forthe  2S ISR signal Monte Carlo (more than 95% of theISR events come from  2S). In Fig. 2 we show theMJ=  distributions for these events for J= !ee and . Both plots show clear enhancementsaround 4260 MeV=c2, with very little background. Thisbackground is found to be in good agreement with thatdetermined from the sidebands of J= .The mass resolution was determined by fitting the ISRsignal Monte Carlo distributions for MJ=  for 2S and Y4260, assuming zero intrinsic width forboth. The instrumental resolution, full-width at half-Q. HE et al. PHYSICAL REVIEW D 74, 091104(R) (2006)RAPID COMMUNICATIONS091104-2maximum, was thus determined to be 8:2 MeV=c2 for 2S and 10:6 MeV=c2 for Y4260. The data for  2Sand Y4260 enhancements were each fitted with a constantbackground plus the peak shape determined by theMonte Carlo simulation convoluted with the single reso-nance relativistic Breit-Wigner function which includes thephase space factor. The mass, width, peak area, and thebackground were kept free in the fits. The fit for the  2Speak returned N 2S  285 17 counts andM 2S  3685:70 0:24 MeV=c2, which comparesfavorably with the known mass, M 2S  3686:0930:034 MeV=c2 [10]. The fit for the Y4260 enhancementis illustrated in Fig. 3. It results in MY4260 42841716 MeV=c2 and Y4260  733925 MeV=c2.The number of counts in the fitted resonance isNY4260  13:64:73:9. The fit with a single Breit-Wigner has 2=d:o:f:  1:00, a confidence level of 52%,and a significance of 5:4. The significance level for theresonance was obtained as  2 lnL0=Lmaxp, whereLmax is the maximum likelihood value for the fit withresonance, and L0 is the likelihood value for the fit withoutresonance.The systematic errors in our measurements ofMY4260 and Y4260 are much smaller than thestatistical errors. An estimate of the systematic error inour mass measurement for Y4260 is provided by our FIG. 2 (color online). Event distributions after kinematic fit-ting for the invariant mass MJ= , with J= ! eeand . Evidence for the production of Y4260 is present inboth distributions. FIG. 3 (color online). The MJ=  distribution for thesum of J= ! ee and J= ! . The dotted line de-notes the fitted background, and the solid curve denotes the fitwith a single resonance. The semilog plot in the insert illustratesthe  2S excitation in the extended mass region. FIG. 1 (color online). Distributions of data events (points) forM2miss, as defined in the text. The peaks centered at M2miss  0and bounded by the dashed lines correspond to the missing ISRphotons. The shaded histograms show  2S ISR signalMonte Carlo predictions normalized to the peak counts.CONFIRMATION OF THE Y4260 RESONANCE . . . PHYSICAL REVIEW D 74, 091104(R) (2006)RAPID COMMUNICATIONS091104-3result for M 2S. As mentioned earlier, our measuredmass M 2S differs from its known value by only0:4 0:2 MeV=c2. Additional contributions to the sys-tematic uncertainty in MY4260 and Y4260 wereestimated by fitting the Y4260 peak in the data by varyingby 50% the resolution width returned by our ISRMonte Carlo sample. We have also studied the effect ofvariations in event selection cuts (M2miss, pT , Eneut, 2 forvertex and MJ=  constraints, lepton identification crite-ria), and variations in peak shape and background parame-terization. The maximum variation found was4 MeV=c2in MY4260 and 5 MeV=c2 in Y4260, which wetherefore assign as systematic uncertainties.Thus our final results for the mass and width are MY4260  42841716stat  4syst MeV=c2;Y4260  733925stat  5syst MeV=c2:The quantity eeY BY ! J=  is related tothe observed counts NY as eeY BY ! J=  NY=BJ= ! llL Y  ISRY;where L is the integrated luminosity, Y is the efficiencydetermined by the ISR signal Monte Carlo, and ISRY isthe value of the ISR cross section per keV=c2 of di-electronwidth calculated using the theoretical formalism of Kuraevand Fadin [11].From our sample of  2S ISR events, for whichee 2S B 2S ! J=  is known [10], wefind that our ISR signal Monte Carlo efficiency  2S isoverestimated by a factor of 1.5. We attribute this to thefact that because of the extreme forward nature of the ISRevents the geometrical acceptance of our detector(j cosj< 0:93) allows us to accept only approximately15% of the phase space for  2S, and we become ex-tremely sensitive to the Monte Carlo modeling of the ISRproduction mechanism. For Y4260 events the geometri-cal acceptance of our detector is larger, approximately30%, and we therefore expect that the Monte Carlo deter-mined efficiency for the Y4260 events is more accuratethan that for the  2S events. We estimate the appropriateefficiency correction for the Y4260 events to be between1.0 and 1.5, and we assume it to be 1:25 0:25. This is thedominant systematic uncertainty in our measurement ofeeY BY ! J= . Systematic uncertainties inluminosity, ISR, and BJ= ! ll are much smaller.To further minimize the systematic uncertainty in ourdetermination of eeY BY ! J=  we imposethe additional requirement for its estimate that at least onelepton from the J= decay have j cosj< 0:7. As a result,the data were refitted for the Y4260 resonance. The fitreturned NY  8:13:62:9 with a 2=d:o:f:  0:98. WithISRY  6:26 pb=keV, and Y  11:5%=1:250:25, our final result is eeY BY ! J=  8:93:93:1stat  1:8syst eV=c2:This is consistent with the BABAR result.Figure 4 shows that the dipion mass of the Y4260events is enhanced at high mass, as predicted byMonte Carlo generated distribution based on a phase spacemodel modified by rescattering of pions which are in arelative S state [12].In summary, we have confirmed BABAR’s observation ofa new resonance, Y4260, produced in initial state radia-tion. We obtain resonance parameters in agreement withtheirs. A good quality fit to our data is obtained with asingle resonance. The observation of Y4260 productionin ISR and the S-wave phase space distribution of thedipion mass confirm that JPCY4260  1 [1,7]. Thevarious theoretical models proposed for Y4260 have beendiscussed in detail in reviews by Eichten, Lane and Quigg[5], and Swanson [6], but no clear understanding of thenature of Y4260 exists at present. A dedicated resonancescan and good measurements of various decays of Y4260are needed to discriminate among the different theoreticalmodels.We gratefully acknowledge the effort of the CESR staffin providing us with excellent luminosity and runningconditions. D. Cronin-Hennessy and A. Ryd thank theA. P. Sloan Foundation. This work was supported by theNational Science Foundation, the U.S. Department ofEnergy, and the Natural Sciences and EngineeringResearch Council of Canada. FIG. 4 (color online). Dipion mass distribution for data events(points). The shaded histogram is the Monte Carlo prediction forM based on a S-wave phase space model. Neither thedata nor the Monte Carlo distributions have been corrected forthe experimental efficiency.Q. HE et al. PHYSICAL REVIEW D 74, 091104(R) (2006)RAPID COMMUNICATIONS091104-4[1] B. Aubert et al. (BABAR Collaboration), Phys. Rev. Lett.95, 142001 (2005).[2] B. Aubert et al. (BABAR Collaboration), Phys. Rev. D 73,012005 (2006).[3] B. Aubert et al. (BABAR Collaboration), Phys. Rev. D 73,011101 (2006).[4] K. K. Seth, Phys. Rev. D 72, 017501 (2005).[5] E. J. Eichten, K. Lane, and C. Quigg, Phys. Rev. D 73,014014 (2006).[6] E. Swanson, Phys. Rep. 429, 243 (2006).[7] T. E. Coan et al. (CLEO Collaboration), Phys. Rev. Lett.96, 162003 (2006).[8] Y. Kubota et al. (CLEO Collaboration), Nucl. Instrum.Methods Phys. Res., Sect. A 320, 66 (1992); M. Artusoet al., Nucl. Instrum. Methods Phys. Res., Sect. A 554, 147(2005); D. Peterson et al., Nucl. Instrum. Methods Phys.Res., Sect. A 478, 142 (2002).[9] R. Brun et al., GEANT, Report No. 3.15, CERN, ReportNo. #DD/EE/84-1, 1987 (unpublished).[10] W. -M. Yao et al. (Particle Data Group), J. Phys. G 33, 1(2006).[11] E. A. Kuraev and V. S. Fadin, Sov. J. Nucl. Phys. 41, 466(1985).[12] L. S. Brown and R. N. Cahn, Phys. Rev. Lett. 35, 1 (1975).CONFIRMATION OF THE Y4260 RESONANCE . . . PHYSICAL REVIEW D 74, 091104(R) (2006)RAPID COMMUNICATIONS091104-5

Confirmation of the Y(4260) resonance production in initial state radiation

Confirmation of the Y(4260) Resonance Production in ISR

Confirmation of the Y(4260) Resonance Production in ISR

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