Spectroscopy Today BaBar’s Contributions Veronique Ziegler Jefferson Lab

Highlights from BaBar * charm * light quark * heavy quark Spectroscopy BaBar last day of running Highlights from BaBar * charm * light quark * heavy quark Spectroscopy

Charm spectroscopy

The DsJ States Discoveries _ Before 2003, 4 cs mesons known 2 S-wave mesons, Ds (JP = 0−) and Ds∗ (1−) 2 P-wave mesons, Ds1(2536) (1+) and Ds2(2573) (2+) Potential model mass predictions were in good agreement with the measured masses. BaBar discovery of two new states in 2003 Ds0∗(2317)+ → Ds+ π0 Ds1 (2460)+ → Ds*+ π0 with masses well below those predicted by existing potential models and this led to search for alternate interpretations BaBar discovery of the DsJ∗(2860) DsJ*(2860)+ → D0 K+ DsJ*(2860)+ → D+ KS and another structure in the 2.7 GeV/c2 mass region adding yet another component to the complex DsJ spectroscopy picture… Phys.Rev.Lett. 90 242001 (2003) 754 citations Phys.Rev.Lett. 97 222001 (2006) 146 citations

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

A Precision Measurement of the Lc+ Mass Using low Q-value modes Phys.Rev.D72:052006,2005 First Observation PDG PDG Baryon (decaying to a Lc+) masses estimated as mass differences w.r.t. the Lc+ with PDG Lc+ mass added  more precise Lc+ mass measurement affects these baryon mass measurements

Charm Baryon Production at the U(4S) Resonance Typical c.m. momentum (p*) distribution Production from B decays (+some continuum) Continuum production

Production from B decays Study of baryon production in B decays Substantial B meson decay to Xc* 0,+ First observations of these decays Branching Fractions & cross section measurements BF measurement (Phys. Rev. D 78, 112003(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, 112003(2008)) Use of B-  Lc+ p p- to get mass, width and spin of Sc(2455) distribution favors spin 1/2 [solid line] over spin 3/2 [dotted curve] efficiency-corrected background-subtracted _

Production from continuum Precision mass and width measurements on excited charm cascades Observation of the Xc(2980)+,0 and Xc(3077)+,0 & evidence for the Xc(3055)+ and the Xc(3123)+ First observation of the excited singly charmed baryon 􏰛􏰟Wc*(css) in the radiative decay Wc*  􏰛Wc0 g􏰩 First observation of a charm baryons decaying to a charm meson First observation of the Lc(2880)+ in D0p decay Discovery of a new state at m = 2939.8 MeV/c2

Light Quark Spectroscopy From charm baryon decays

Spin measurement of W- from Xc0 → W- K+, W- → L K- decays PRL 97, 112001(2006)

Analysis of Lc+ → X- p+ K+ to obtain X(1530) spin information Only obvious structure: X (1530)0 → X- p+ Lc+ signal region Rectangular Dalitz plot Note: m2(X- K+) depends linearly on cosqX

Analysis of Lc+ → X- p+ K+ to obtain X(1530) spin information unweighted uncorrected Lc+ signal region Efficiency-corrected P4 Moment Dist. X(1530)0 wj = (7/ √2) P4(cosq) from Lc+ signal region efficiency-corrected unweighted m(X- p+) distribution in data Spin 5/2 Test PL moments (L ≥ 6) give no signal wj = √10 P2(cosq) Efficiency-corrected P2 Moment Dist.  spin 3/2 clearly established  spin 5/2 ruled out wj = √10 P2(cosq) from Lc+ signal region Spin 3/2 Test analysis by establishing J=3/2 also established positive parity (i.e. P-wave)

Dalitz Plot for Lc+ → L KS K+ Accumulation of events in KSK+ near threshold  evidence of a0(980)+ Background-subtracted, efficiency-corrected data ― Integrated signal function smeared by mass resolution [Histogram] ― Signal function with no resolution smearing ― |A(a0(980)|2 contribution ― |A(X(1690)|2 contribution ― Interference term contribution a0(980)+ For J(X[1690]) = 1/2 cosqL 14 X(1690)0 m(L KS) (GeV/c2)

BaBar’s contributions to charm baryon spectroscopy 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

Quarkonium spectroscopy

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

Charmonium Production Mechanisms B → cc K(*) decay Initial state radiation JPC = 1- - Two-photon collision Double charmonium production C= +, J= 0, 2 Recoil against J/y  C = +

All charmonium production mechanisms seen at BaBar The X(3872): a charmonium-like state in B± → K± J/ψ p+p- decays (PRD77, 111101(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- → gISR Y(4260) → J/ψ p+p- decays and the subsequently the Y(4350) in e+e- → gISR Y(4350) → ψ(2S) p+p- (PRL95, 142001(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 → hc → K+ K- p0,h [PRD 89, 112004 (2014))

The discovery of bottomonium observed bb bound state CUSB Collaboration 20

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

The Search for the hb at BaBar

The hb(1S) discovered in Y(3S) data and confirmed in Y(2S) data BF measurements: B((3S)  ghb(1S)) = (5.1 ± 0.7)  10-4 B((2S)  ghb(1S)) = (3.9 ± 1.5)  10- 4 Compatible with predictions Combined values of mass and HF splitting: mhb(1S) = 9390.9 ± 2.8 MeV/c2 (Ghb(1S)  10 MeV) (m(1S) – mhb(1S)) = 69.3 ± 2.8 MeV/c2 hb hb S. Godfrey, J.L. Rosner PRD 64 074011 (2001)

Detailed studies of bottomonium transitions from U(3S) events using g→e+e- conversions Resolution dominated Small Doppler broadening

Evidence for the hb(1P) in the decay U(3S) pohb background-subtracted result: hb signal region uncertainty from background fit 10814± 2813 signal events M(hb) = 9902±4 ±2 MeV/c2 (C.G.=9899.87±0.27 MeV/c2 ) Phys.Rev. D84 (2011) 091101

The hb(1P) and hb(2P) seen by Belle in e+e-→ p+p- transitions at the U(5S) Phys.Rev.Lett. 108, 032001 (2012) p+p- recoil mass spectrum hb(2P) hb(1P) Measured hb(1,2P) mass values consistent with predictions BaBar hb(1P) mass measurement consistent with Belle’s Observed hb production rate enhancement may be indicative of exotic process violating HQ spin-flip suppression 26

Future directions 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 π1(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 1407.7244, recently accepted in PRD] that shows an interesting structure in m(J/ψ f)… 27