Outline THE EXOTIC Y STATES. UPDATE OF THE π + π - ψ(2s) ISR ANALYSIS AT BABAR

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2 Outline THE EXOTIC Y STATES UPDATE OF THE π + π - J/ψ ISR ANALYSIS AT BABAR Context New π + π - J/ψ results Analysis of π + π - in π + π - J/ψ Suary UPDATE OF THE π + π - ψ(s) ISR ANALYSIS AT BABAR Context New π + π - ψ(s) results Analysis of π + π - in π + π - ψ(s) Suary

3 The exotic Y states 3 Exotic charoniu- like states above open- char threshold Need no introduc,on here! Focus priarily on the Y candidates: J PC = 1 Production technique Pseudo- direct produc,on in ISR events Look at strong decay odes strongly suppressed for charoniu above threshold [such as Y π + π - J/ψ] Previous BaBar analyses using the ISR ethod discovered the Y(460) and Y(435) but were based on par,al datasets Re- analyze in ISR odes with full BaBar dataset Y(4660) Y(435) Y(460) Y(4008)

4 Update of the π + π - J/ψ ISR analysis at BaBar PRD-RC 86, (01)

5 The π + π - J/ψ ode in ISR 5 Radiative Return technique ee collider opera,ng at higher resonances ISR events lower CM energy of ee collision Direct produc,on of J PC = 1 states Exis,ng data provide effec,ve scan of energies at charoniu levels Explicit reconstruc,on of ISR photon not necessary ISR production in charoniu region Direct produc,on of any J PC = 1 state X Plausible X decay odes include X π + π - J/ψ If X is charoniu, this ode is highly suppressed above the open- char threshold: e + e γ ISR X X π + π - J/ψ J/ψ l + l Exo,c state enhanceents seen in this ode Reains one of the ost frui\ul analysis odes

6 Context: previous π + π - J/ψ results 6 33fb -1 BaBar: Y(460) observation PRL 95, (005) 8σ enhanceent with ISR ethod Y (460) Y (460) = (459 ± 8 = (88 ± ) MeV ) MeV / c

7 Context: previous π + π - J/ψ results 7 33fb -1 CLEO III 13.3fb -1 BaBar: Y(460) observation PRL 95, (005) 8σ enhanceent with ISR ethod CLEO: Y(460) confiration CLEO III: ISR ethod [pictured] PRD 74, (R) (006) CLEO- c: scan/direct produc,on PRL 96, (006) π 0 π 0 ode iplies 0 isospin Y (460) = (459 ± ) MeV / c Y (460) = (484 ± ) MeV / c Y (460) = (88 ± ) MeV Y (460) = (73 ± ) MeV

8 Context: previous π + π - J/ψ results 8 33fb -1 CLEO III 13.3fb fb -1 BaBar: Y(460) observation PRL 95, (005) 8σ enhanceent with ISR ethod Y (460) Y (460) = (459 ± 8 = (88 ± ) MeV / c ) MeV CLEO: Y(460) confiration CLEO III: ISR ethod [pictured] PRD 74, (R) (006) CLEO- c: scan/direct produc,on PRL 96, (006) π 0 π 0 ode iplies 0 isospin Y (460) Y (460) = (484 ± 4 = (73 ± ) MeV ) MeV / c Belle: Y(460) + Y(4008) ISR ethod PRD 99, (007) Second enhanceent Y(4008) Y (460) Y (460) Y (4008) Y (4008) = (447 ± ) MeV / c = (108± 19 ± 10) MeV = (4008 ± = (6 ± 44 ± 87) MeV ) MeV / c

9 Context: previous π + π - J/ψ results 9 33fb -1 CLEO III 13.3fb fb -1 BaBar: Y(460) observation PRL 95, (005) 8σ enhanceent with ISR ethod Y (460) Y (460) = (459 ± 8 = (88 ± ) MeV / c ) MeV CLEO: Y(460) confiration CLEO III: ISR ethod [pictured] PRD 74, (R) (006) CLEO- c: scan/direct produc,on PRL 96, (006) π 0 π 0 ode iplies 0 isospin Y (460) Y (460) = (484 ± 4 = (73 ± ) MeV ) MeV / c Belle: Y(460) + Y(4008) ISR ethod PRD 99, (007) Second enhanceent Y(4008) Y (460) Y (460) Y (4008) Y (4008) = (447 ± ) MeV / c = (108± 19 ± 10) MeV = (4008 ± = (6 ± 44 ± 87) MeV ) MeV / c

10 New π + π - J/ψ results 10 π + π - J/ψ invariant ass plot [right] Clear Y(460) peak Background [yellow] is interpolated fro J/ψ sidebands in (l + l ) distribu,on Where is the Y(4008)? What is the enhanceent at the low end? Y(460) results consistent with Belle 454fb -1 Y (460) Y (460) Y (4008) Y (4008) Belle 007 BaBar 01 = (447 ± ) MeV / c = (108± 19 ± 10) MeV = (4008 ± = (6 ± 44 ± 87) MeV ) MeV / c Y (460) Y (460) = (444 ± 5 ± 4) MeV = ( ± 7) MeV / c 548fb -1

11 The excess 11 Could it be fro the ψ(s) peak? Below ~3800MeV, the huge peak fro ψ(s) π + π - J/ψ doinates; perhaps the excess is stray wing events fro this process Use [corrected] MC to odel contribu,on to (π + π - J/ψ ) in the Y(460) window [Top] MC/data correspondence in ψ(s) region, background- subtracted [Boho] MC/data up to 4GeV ψ(s) tail appears to odel data in high- E tail correctly, but disagreeent in low- E region iplies nonresonant contribu,on Extrapola,on of BW lineshape to signal region is problea,c Con=nuu contribu=on to cross sec=on sees to be issing

12 Analysis of π + π - in π + π - J/ψ 1 What is the π + π - ass structure in Y(460) π + π - J/ψ? Width indicates strong decay Y(460) has I(J PC )=0(1 - - ), sae as J/ψ; π + π - syste ust have 0(0 ++ ) or 0( ++ ) Select Y(460) peak: 4.15 < (π + π - J/ψ) < 4.45 GeV/c Background- subtracted (π + π - ) distribu,on shows peak just below f 0 (980) [0(0 ++ )] Odd- looking peak resebles interference effect?

13 Analysis of π + π - in π + π - J/ψ 13 Angular distribution Define θ π as the angle between the π + and the recoil J/ψ both in the dipion rest frae [below] cos θ π plot fihed with S- wave distribu,on (blue line) Consistent with S- wave hypothesis (χ /NDF = 1.3/9, probability = 19.7%) Consistent with f 0 (980)

14 Analysis of π + π - in π + π - J/ψ Model π + π - ass distribution Peak ight be caused by interference between a resonant aplitude describing the f 0 (980) and π + π - con,nuu Take ass dependence of f 0 (980) aplitude and phase fro previous BaBar analysis Add nonresonant polynoial aplitude o,vated by a QCD ul,pole expansion In fit, allow rela,ve strength and phase of coponents to vary Resultant fit [BOTTOM] requires soe f 0 (980) contribu,on but it is not the doinant source of the peak qualita=vely consistent with BES results [PRD 79, (009)] 14 + B( Y(460) J ψ f0 (980), f0(980) π π ) = (17 ± 13)% + B( Y(460) π π J ψ )

15 Suary of π + π - J/ψ 15 Y(460) ass/width Y (460) Y (460) = (444 ± 5 ± 4) MeV = ( ± 7) MeV / c 454fb -1 No evidence for Y(4008) Cross- section enhanceent at low energies that is not fully explained Soe f 0 (980) coponent in Y(460) π + π - J/ ψ decays present

16 Update of the π + π - ψ(s) ISR analysis at BaBar arxiv:

17 The π + π - ψ(s) ode in ISR 17 ISR production in charoniu region Analogous to π + π - J/ψ with X π + π - ψ(s) Plausible access to other exo,c states Main decay ode: e + e γ ISR X X π + π - ψ(s) ψ(s) π + π - J/ψ J/ψ l + l Addi,onal ode: e + e γ ISR X X π + π - ψ(s) ψ(s) l + l

18 Context: previous π + π - ψ(s) results 18 98fb fb -1 BaBar: Y(4350) observation Search for Y(460) Poor atch to Y(460) lineshape [dashed] Instead, Y(435) observed PRL 98, 1001 (007) Y (435) Y (435) = (434 ± 4) MeV / c = (17 ± 33) MeV Belle: Y(4350) + Y(4660) PRD 99, (007) Y (435) Y (435) Y (4660) Y (4660) = (4361± 9 ± 9) MeV / c = (74 ± 15 ± 10) MeV = (4664 ± 11± 5) MeV / c = (48 ± 15 ± 3) MeV

19 Context: previous π + π - ψ(s) results 19 98fb fb -1 BaBar: Y(4350) observation PRL 98, 1001 (007) ISR ethod Poor atch to Y(460) [dashed] Y (435) Y (435) = (434 ± 4) MeV = (17 ± 33) MeV / c Belle: Y(4350) + Y(4660) PRD 99, (007) Y (435) Y (435) Y (4660) Y (4660) = (4361± 9 ± 9) MeV / c = (74 ± 15 ± 10) MeV = (4664 ± 11± 5) MeV / c = (48 ± 15 ± 3) MeV

20 New π + π - ψ(s) results 0 ψ(s) π + π - J/ψ [top] [added Υ(,3S) runs] Very sall background fro ψ(s) sidebands Y(4660) confired Overlapping peaks have iden,cal PC; interference ters do not cancel in ass projec,on Branching frac,on easureent depends on interference assup,on: construc=ve and destruc=ve 50fb -1 ψ(s) l + l - [botto] More data Much ore background [supports Y(4660) but does not iprove ass or width easureents]

21 Y(4360) π + π - ψ(s) 1 π + π - Invariant ass plot [below] Very low sta,s,cs 41 events GeV region of the (π + π - ψ(s)) distribu,on Blue histogra is MC es,a,on given resonance at 4.36GeV based on phase space No conclusive disagreeent [siilar to Belle findings]?

22 Y(4660) π + π - ψ(s) π + π - Invariant ass plot [below] Very low sta,s,cs 4 events GeV region of the (π + π - ψ(s)) distribu,on Blue histogra is MC es,a,on given resonance at 4.66GeV based on phase space Possible f 0 (980) contribu=on?

23 π + π - ψ(s) suary 3 BaBar/Belle Y(4360) seen with siilar ass/width to Belle confira,on Y(4660) confired with consistent ass/width Invariant ass spectra are very siilar [top] Cobined spectru [boho]: 1.ab - 1! Huge datasets required to get substan,ally beher results fro ISR ethod Y (435) Y (435) Y (4660) Y (4660) Belle 007 BaBar 01 = (4361± 9 ± 9) MeV / c = (74 ± 15 ± 10) MeV = (4664 ± 11± 5) MeV / c = (48 ± 15 ± 3) MeV Y Decays Nothing conclusive fro Y(4360) Y(4660) ay have an f 0 (980) contribu,on Y (435) Y (435) Y (4660) Y (4660) = (4340 ± 16 ± 9) MeV / c = (94 ± 3 ± 13) MeV = (4669 ± 1± 3) MeV / c = (104 ± 48 ± 10) MeV