Pentaquark Searches and DsJ Studies in BaBar The 32nd International Conference on High Energy Physics Beijing August 16-22 Pentaquark Searches and DsJ Studies in BaBar Update on DsJ Masses Inclusive Search for qs+(1540) Inclusive Searches for X5(1860) states Inclusive Search for Possible N5, S5 Pentaquarks Search for q*++(~1600) in B+ppK+ Decays 10-0631 10-0632 10-0970 Valerie Halyo (SLAC) Representing the BaBar Collaboration 1/18/2019

The BaBar Experiment e+e-  hadrons Detector optimized for B physics Excellent tracking Excellent particle identification Excellent g, p0 detection Data: ~90% @ =10.58 U(4s) ~10% @ =10.54 qq 244 fb-1 recorded so far 256M B decays 510M uds events 317M cc events 1/18/2019

Particle Identification dE/dx from Drift Chamber Cherenkov angle from DIRC Distinguishing between p, p/m, K 1/18/2019

DsJ Event selection Identify DsK+K-p+ along with any number of p+, p0, g Kaon identification Vertex fit (c2 probability > 1%) Consistent with production at the interaction region Eg >100 MeV p* (momentum in center of mass) larger than 2.5 GeV See also talk by Mat Charles (Heavy Quarks, Wed. Aug 18 HQ(5) 11-0630) 1/18/2019 m(K+ K- p+) GeV/c2

Ds and Neutrals 1/18/2019

Ds and Neutrals Limits on have large uncertainties due to overlapping reflections 1/18/2019

Ds and Neutrals Measure DsJ reflection yield Establish decay mode 2-dimensional likelihood fit on projection Sideband Sideband Signal Region Signal Region Sideband Sideband Ds+p0g Invariant Mass GeV/c2 Ds+g Invariant Mass GeV/c2 Ds+p0 Invariant Mass GeV/c2 1/18/2019

Ds and Charged Search for DsJ(2317) Partners Neutral D+sJp- system Ds+p+p- Invariant Mass GeV/c2 Preliminary Results From 3 modes Double Charged D+sJp+ system Ds+p+/- Invariant Mass GeV/c2 No signals evident No evidence for 2317Ds+p+p- 1/18/2019

Motivation for Pentaquark Searches Claims of Exotic Narrow Baryons q+(ududs): LEPS+CLAS+others m=1542 5 MeV/c2 G< 21 MeV/c2 X--(dsdsu): NA49 m=1862 2 MeV/c2 G< 18 MeV/c2 qc0(ududc): H1 m=3099 6 MeV/c2 G < 28 MeV/c2 If pentaquark production is the same as other baryon production then we expect: ~ 8x10-4 qs+ per event ~ 4x10-5 X5-- per event 1/18/2019

The BaBar Search Strategy Pentaquark theory expects q5s+, X5 to be members of the 105+85 Dedicated searches for claimed states, q5s+, X5--, X50, q5c0 Inclusive searches for other states in the 105+85 Specific searches for selected states from other multiplets :q*++ 5 1/18/2019

Search for q5+(1540)p Ks0 No Signal of q5+ Lc+(2285) 1540 Clean Ks0 p+p- reconstruction using geometrical cuts Clean protons using dE/dx and Cherenkov angle Clear Lc+ sample with 52000 events No structure near 1540 MeV/c2 No narrow structure except Lc+ Many additional/different cuts tried; same results 1/18/2019

Lc+  p Ks0 Control Sample Fit signal in bins of p* Check mass scale Shape of resolution function same as simulation Width of resolution function same Yield consistent with expectations (Efficiency ~30%) Now fit for q5+: P-wave Breit-Wigner signal x Fthreshold resolution function Resolution ~2 MeV/c2 due to proximity to threshold Assume G=8 MeV/c2 best experimental upper limit Assume G=1 MeV/c2 very narrow state MC simulation of mass resolution tracks data very well. 1/18/2019

q+ Cross Section and Upper Limit Model independent limits on the total production cross section @ 95% C.L. : = 1 G = 8 MeV/c2 < 182.8 < 363.1 fb < 5.4x10-5 < 10.7x10-5 per qq event < 17.9x10-5 < 35.0x10-5 per U(4s) Fitted yields consistent with zero We derived @ 95% C.L. a model independent cross section upper limit as a function of momentum 1/18/2019

Search for X5--X-p- and X50X-p+ IP We look for inclusive production of : Geometrical selection of two displaced vertices Loose particle ID Select masses near the nominal L0 and X- masses Control particles: X*0(1530)X-p+, Xc(2470) X-p+ 1/18/2019

X-p-, X-p+ Invariant Mass 95% C.L. U.L. on X-- prod. cross section: < 33.7 fb < 1.0x10-5 per qq < 3.2x10-5 per U(4s) (G = 18 MeV/c2) No Signal of X5-- ~5K events ~2K events No Signal of X50 1/18/2019

Search for X50 L0 Ks0 No Signal of X50 Analysis method similar to above Xc0 L0Ks0 seen, ~2K events No Signal of X50 95% C.L. U.L. on X50 production cross-section x BF : < 82.8 fb G=1MeV/c2 <204.7 fb G=18MeV/c2 < 1/18/2019

Search for X- L0 K- No Signal of X5- L0 selection as above Combine with identified K- Control particle W-, ~8K events No Signal of X5- 95% C.L. U.L. on production cross-section x BF : < 83.6 fb G=1MeV/c2 <181.0 fb G=18MeV/c2 1/18/2019

Additional Searches Also S0K+, S0K-, S0Ks0 N5+(uudss)L0K+ N50(uddss)L0Ks S5+(uudss)pKs Also S0K+, S0K-, S0Ks0 No unexpected narrow structure M(p Ks) in [1.60 – 1.8 ] GeV/c2 1/18/2019

Results in perspective Assume pentaquarks have J= ½ BF(q+p Ks0) = 25% BF(X5-- X-p-) = 50% BF for X5-, X50 very unclear Limits are below expectations for baryons: q5+ by a factor of 8-15 X-- by a factor of 4-6 1/18/2019

Exclusive Search for q*++ (pK+) Prediction for a q*++(uuuds) pentaquark I=1, I3=1 m(q*++) = [1.43—1.7] GeV/c2 G = [37—80] MeV/c2 We searched in the exclusive B+q*++ppK+p decay. 81 fb-1 data sample was used; 89M BB events “Standard” B decay analysis used, (see talks in CP-violation, Heavy Quark sessions) 1/18/2019

BppK+ Measurement BF(BppK+) = (6.7 0.9(stat.) 0.6(syst.))x10-6 5.276 < mES < 5.286 GeV DE < 29 MeV 212 events in the signal region ~68 events have charmonium decays to pp ~40 background events BF(BppK+) = (6.7 0.9(stat.) 0.6(syst.))x10-6 1/18/2019

Upper Limit on q*++ BF(B+q*++(pK+)p) < 1.49x10-7 @ 90% C.L. Projection on pK+ axis Events outside the Charmonium region Events in the Charmonium region No entries for m q*++ < 1850 MeV/c2 BF(B+q*++(pK+)p) < 1.49x10-7 @ 90% C.L. 1/18/2019

Summary Improved measurements of DsJ*(2317), DsJ(2460), DsI(2536) masses. Many L0, X-, X*0, -, Xc0, Lc+ baryons found in our data. No signal for any pentaquark seen: Production of q+(1540), X--(1860) well below ordinary baryons of similar mass. No narrow peaks for hypothetical 105+85 states in several search modes. No signal for the hypothetical q*++pK+; BF(B+q*++ppK+p) < 1.5x10-7 @ 90% C.L. 1/18/2019