BaBar s Contributions. Veronique Ziegler Jefferson Lab

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1 BaBar s Contributions Veronique Ziegler Jefferson Lab

2 BaBar last day of running charm light quark heavy quark 2

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4 _ Before 2003, 4 cs mesons known 2 S-wave mesons, D s (J P = 0 ) and D s (1 ) 2 P-wave mesons, D s1 (2536) (1 + ) and D s2 (2573) (2 + ) Potential model mass predictions were in good agreement with the measured masses. BaBar discovery of two new states in 2003 D s0 (2317) + D s + π 0 D s1 (2460) + D s + π 0 Phys.Rev.Lett (2003) with masses well below those predicted by existing potential models and this led to search for alternate interpretations 4 BaBar discovery of the D sj (2860) D sj (2860) + D 0 K + D sj (2860) + D + K S and another structure in the 2.7 GeV/c 2 mass region Phys.Rev.Lett (2006) adding yet another component to the complex D sj spectroscopy picture

5 BaBar as a Charm Baryon Factory 5 Access to rare decay modes & High precision studies of charm baryon properties...

6 Phys.Rev.D72:052006,2005 PDG Using low Q-value modes L c LK Q S K evts MeV/c 2 First Observation PDG L c Q K 0 S K evts MeV/c 2 m( L ) 0 c LK S K ( stat) 0.144( syst) 2 MeV/c m( L ) 0 0 c K S K ( stat) 0.126( syst) 2 MeV/c Combined measurement m( L c ) MeV/c PDG 2004 : MeV/c Baryon (decaying to a L c+ ) masses estimated as mass differences w.r.t. the L c+ with PDG L c + mass added more precise L c+ mass measurement affects these baryon mass measurements 6

7 Production from B decays (+some continuum) Continuum production 7

8 Study of baryon production in B decays Substantial B meson decay to X c 0,+ First observations of these decays Branching Fractions & cross section measurements efficiency-corrected background-subtracted X c BF measurement (Phys. Rev. D 78, (2008)) indicates 3-body final state favored in agreement with the predictions of Hou and Soni (Phys. Rev. Lett. 86, 4247 (2001)) Spin measurement possibilities (Phys. Rev. D 78, (2008)) _ Use of B - L c+ p p - to get mass, width and spin of c (2455) distribution favors spin 1/2 [solid line] over spin 3/2 [dotted curve] 8

9 Precision mass and width measurements on excited charm cascades Observation of the X c (2980) +,0 and X c (3077) +,0 & evidence for the X c (3055) + and the X c (3123) + First observation of the excited singly charmed baryon W c (css) in the radiative decay W c W c 0 g First observation of a charm baryons decaying to a charm meson First observation of the L c (2880) + in D 0 p decay Discovery of a new state at m = MeV/c 2 9

10 From charm baryon decays 10

11 PRL 97, (2006) 11

12 Analysis of L c+ X - p + K + to obtain X(1530) spin information Only obvious structure: X (1530) 0 X - p + Rectangular Dalitz plot L c+ signal region Note: m 2 (X - K + ) depends linearly on cosq X 12

13 Analysis of L c+ X - p + K + to obtain X(1530) spin information L c+ signal region uncorrected X(1530) unweighted 0 efficiency-corrected unweighted m(x - p+) distribution in data Efficiency-corrected P 4 Moment Dist. w j = (7/ 2) P 4 (cosq) from L c+ signal region Spin 5/2 Test P L moments (L 6) give no signal Efficiency-corrected P 2 Moment Dist. w j = 10 P 2 (cosq) wfrom j = 10 L c+ Psignal 2 (cosq) region Spin 3/2 Test spin 3/2 clearly established spin 5/2 ruled out analysis by establishing J=3/2 also established positive parity (i.e. P-wave) 13

14 L K S cosq L a 0 (980) + Accumulation of events in K S K + near threshold evidence of a 0 (980) + For the X(1690) 0 we obtain: m = ± 0.9(stat)± 0.8(syst) MeV/c 2 G = (stat)± 0.4(syst) MeV J =1/2 favored Background-subtracted, efficiency-corrected data Integrated signal function smeared by mass resolution [Histogram] Signal function with no resolution smearing A(a 0 (980) 2 contribution A(X(1690) 2 contribution Interference term contribution For J(X[1690]) = 1/2 14 X(1690) 0 14 m(l K S ) (GeV/c 2 )

15 X c (3123) X c (3077) X c (3055) L c(2940) X c (2980) Insight into charm baryon production Measurements of charm baryon spin from exclusive B decay processes Insight into light quark spectroscopy from hyperon resonances produced in charm baryon decay L c(2880) L c(2625) L c(2393) c (2800) c (2520) X c (2815) X c (2790) X c (2645) Xc W c 0 W c X c L c 15

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17 PRL 33, 1406 (1974) charmonium Discovery of a narrow width state with mass 3.1 GeV and BNL by SLAC pn e + e - X e + e - hadrons BNL J J/ψ resonance SLAC ψ(3100) PRL 33, 1404 (1974) discovery of the charm quark, J/y was the first observed cc bound state 17

18 B cc K() decay Initial state radiation J PC = Two-photon collision Double charmonium production C= +, J= 0, 2 Recoil against J/y C = + 18

19 All charmonium production mechanisms seen at BaBar The X(3872): a charmonium-like state in B ± K ± J/ψ p p - decays (PRD77, (2008)) opened the door to exotic meson interpretations BaBar pins down C-parity (+) from observation of the X in J/y g and excludes the isovector hypothesis from lack of evidence for a charged partner BaBar discovers the Y(4260) in ISR: e + e - g ISR Y(4260) J/ψ p p - decays and the subsequently the Y(4350) in e + e - g ISR Y(4350) ψ(2s) p p - (PRL95, (2006)) Improbable interpretation of both states as charmonium Y(4260) J/ψ p p - Also significant BaBar contributions to charmonium states seen in double charmonium production & 2 photon collisions (e.g. gg h c K + K - p 0,h [PRD 89, (2014)) 19

20 bottomonium observed bb bound state CUSB Collaboration 20 20

21 21 Opened the door over 30 years of discoveries in the Bottomonium Sector!

22 22 The Search for the h b at BaBar

23 The h b (1S) discovered in Y(3S) data and confirmed in Y(2S) data h b h b BF measurements: B((3S) gh b (1S)) = (5.1 ± 0.7) 10-4 B((2S) gh b (1S)) = (3.9 ± 1.5) 10-4 Compatible with predictions S. Godfrey, J.L. Rosner PRD (2001) Combined values of mass and HF splitting: m hb (1S) = ± 2.8 MeV/c 2 (G hb (1S) 10 MeV) (m (1S) m hb (1S)) = 69.3 ± 2.8 MeV/c 2 23

24 Detailed studies of bottomonium transitions from (3S) events using g e + e - conversions Resolution dominated Small Doppler broadening ( 2P) g (2S) bj 24

25 Evidence for the h b (1P) in the decay (3S) p o h b background-subtracted result: h b signal region uncertainty from background fit Phys.Rev. D84 (2011) ± 2813 signal events M(h b ) = 9902±4 ±2 MeV/c 2 (C.G.= ±0.27 MeV/c 2 ) 25

26 The h b (1P) and h b (2P) seen by Belle in e + e - p p - transitions at the (5S) Phys.Rev.Lett. 108, (2012) p p - recoil mass spectrum h b (1P) h b (2P) Measured h b (1,2P) mass values consistent with predictions BaBar h b (1P) mass measurement consistent with Belle s 26 Observed h b production rate enhancement may be indicative of exotic process violating HQ spin-flip suppression

27 Spectroscopy at J-Lab with 12 GeV Unique photo-production research opportunities to identify exotics by amplitude analyses of final states hadron spectroscopy by coherent bremsstrahlung production in Hall D and by tagged (quasi-)real photoproduction in Hall B to yield complementary results Many new results from the LHC spectroscopy of X, Y, Z states, bottomonium spectroscopy heavy flavor baryon data, COMPASS hadron program is to study the light-quark hadron spectrum, and in particular, to search for evidence of hybrids and glueballs (COMPASS confirms previous Brookhaven discovery of the π 1 (1600) 1 -+ wave in rp). BESIII continues to make detailed explorations of the region just above the charmonium threshold. BaBar continues to produce interesting results such as the analysis of B J/ψ f K [hep-ex , recently accepted in PRD] that shows an interesting structure in m(j/ψ f) 27