Spectroscopy of hadrons with b quarks. Rick Van Kooten Indiana University (Representing [mostly] the CDF & DØ Collaborations)

Transcription

1 Spectroscopy of hadrons with quarks Rick Van Kooten Indiana University (Representing [mostly] the CDF & DØ Collaorations)

2 Motivation Why BHadron Spectroscopy? Heavy quark hadrons are the "hydrogen atom" of QCD, and hadrons offer the heaviest quarks in ound systems Very sensitive tests of potential models, HQET, and all regimes of QCD in general, including lattice gauge calculations Why at the Tevatron? Produce heavier states not accessile anywhere else: Complementary to B factories...

3 Motivation Why BHadron Spectroscopy? Heavy quark hadrons are the "hydrogen atom" of QCD, and hadrons offer the heaviest quarks in ound systems Very sensitive tests of potential models, HQET, and all regimes of QCD in general, including lattice gauge calculations Outline: Heavy Mesons Heavy Baryons Talks earlier in conf Complementary to B factories ut for completeness...

4 + B B Mass Difference entries / (.15 GeV/c) Proes size of Coulom contriutions to the quark structure of mesons Predictions ~uncertain since contriutions from quarkmass difference m(d) m(u) and from Coulom effects have similar magnitudes and opposite signs BABAR entries / (.15 GeV/c) 1 1 arxiv: (this week) 1 pure signal signal with radiation BB ackground qq ackground p(m + m K + ) (GeV/c) p(m + m K + p ) (GeV/c) Compare the two reconstructed momentum distriutions PDG 7 World Average

5 B Meson c Unique in that it contains two different heavy quarks Decays: via quark via c quark annihilation Expected to have lifetime ~1/3 of other hadrons (decay length cuts not as effective at reducing ackgrounds) Optimize selection critera on control channel similar cuts on, take enough data... Entries per.5 MeV/c Num(Bu): 197±15 Mass: ±.1 MeV/c s: 1.8 ±.1 CDF Preliminary M(J/y K ± ) (GeV/c ) CDF Numer of Events / 3 MeV/c 7 1 D, L=1.3 f DØ M(J/y K ) (GeV/c ) first evidence, ut poor mass measurement trigger, mass const.

6 Entries per 1 MeV/c 5 5 B Meson c arxiv:71.156, sumitted to PRL CDF Mass(J/yp) GeV/c >8s Comparison to predictions: DØ DØ ) Events / ( 4 MeV/c arxiv:8.458, sumitted to PRL DØ 1 DØ, 1.3 f >5s Invariant Mass (GeV/c ) M(mmp) [GeV/c ] CDF Different models Experimental measurements now smaller undertainty than uncertainties on theoretical predictions

7 d, s Spectroscopy Hydrogen atom of strongly interacting systems Q q (+ gluon degrees of freedom, "rown muck") ) Mass (GeV/c P J B u,d, (s) q Oritally Excited B Mesons L = 1 s Q j j = s + L J = + q j q j q q = 1/ J =, 1 = 3/ J = 1, Collectively referred to as: j =1/ j =1/ =3/ q L= L= B B1 B 1 B Swave p Wide g q B u,d, (s) j q + Dwave p Narrow p Threshold B, B' 1 B, B 1 B B, B' s B B J B s J s s1 B B s1, s foridden y conservation of parity and angular momentum ut first aout that g...

8 B s State E (GeV).5 CLEO 13 candidates.5.5 Phys. Rev. Lett. 96, 151 (6) 4 Events/(.5 MeV/c ) M c (B s candidate) (GeV/c ) 3 1 M c (GeV/c ) 5.5 Belle (a) arxiv:hepex/613 () DE (GeV) Running at the, utilize the eamconstrained invariant mass peak positions for and Similarly, Belle 1.8s higher My average (including CUSB measurement) s s

9 B States Numer of Events / 1 MeV/c DØ >7s Phys. Rev. Lett. 99, 171 (7 ) Missing g D, L=1.3 f M(B p ) M(B ) (GeV/c + ) Reconstruct then add a pion Do not reconstruct (~3k) First time these states were separated

10 B States Candidates per 5 MeV/c Kinematic Threshold CDF CDF II Preliminary CDF Note 8945 L ~ 1.5 f Total Fit B 1 Æ B p Æ B p Q = m(bp) m(b) m p (GeV/c ) B B Æ Bp B s1 Æ B Bs K Æ BK Background 1 Reconstruct CDF adds: (~5k) (~37k) (~1k) then add a pion (clear peaking structure in each of these 3 channels)

11 Numer of Events / 3 MeV/c DØ B States s 1 D, L=1.3 f >5s Phys. Rev. Lett. 1, 8 (8) Reconstruct add a kaon instead of pion Numer of Events / 3 MeV/c M(B K ) M(B ) M(K ) (MeV/c ) 14 1 D, L=1.3 f ? M(B K ) M(B ) M(K ) (MeV/c ) Try fitting for ; statistical significance is less than 3s. Hence with the current data, the existence of a state can e neither confirmed nor excluded. This close to threshold, would expect heavy (factor ~.74) phasespace suppression

12 B States s Candidates per 1.5 MeV/c 1 1 CDF arxiv: B s candidates with B s candidates with Reconstruct CDF adds: then add a kaon (instead of a pion) (two peaks in each of these two channels) Comined 4 (c) First evidence of narrow state m(b K )m(b )M K [MeV/c ]

13 B Summary (s) Theory: 1. Matsuki et al., hepph/6519. Eert et al., PRD 57, 5663; 3. Eichen et al., PRL 71, 4116 Phys. Rev. Lett. 99, 171 (7) CDF Pulic Note 8945 CDF(prel). DØ Theory p CDF Note p CDF Note Mass (MeV) Phys. Rev. Lett. 1, 8 (8) Phys. Rev. Lett. 11, 8 (8) Predicted from DØ threshold 1, Mass (MeV)

14 New Flavored Baryons J =3/ Baryons S S J =1/ Baryons X dd ud uu ds us X W ss X dds n dss X d u s W udd uds L,S uud L,S uss X X p uus S + S D S X ddd dds S X W W d u s S ud dd X ds us D ss W udd uds S dss uss sss X uu X D + W X uud uus S + uuu S + D ++ Until recently, ground state was the only directly oserved aryon More statistics, look for other aryon states

15 S Heavy Baryon L= "atomic" system, heavy quark and light diquark : : : uu dd ud q q spin: spin1: tough at Tevatron 3/ + : : qq Predictions from HQET,Lattice QCD, potential models, sum rules: 1/ + : Diquark spin alignment Hyperfine mass splitting Isospin (u, d diff.)

16 S Heavy Baryon p Form a large optimized sample of Strong decay p± K Candidates per MeV/c CDF PRL 99, 1 (7) 1.1 f 1 PV Total Fit Partiallyreconstructed L Fullyreconstructed B Partiallyreconstructed B Cominatorial Data L N( ) = 318 ± L c p m(l c ) GeV/c L L c p Then add a pion Estimate ackgrounds: with random hadronization tracks (89%) other hadrons (~7%) cominatorics (~3%) Fit for Q values and no. of events p +

17 S Heavy Baryon Candidates per 5 MeV/c CDF Data Total Fit Background S S + S S Candidates / (1 MeV/c Candidates / (1 MeV/c PRL 99, 1 (7) 8 ) 6 4 ) Constrain Two peaks for each charge, 5.s significance w.r.t. no signal Use CDF II measurement of to get asolute masses: Q = m(l p) ) m(l ) m p (MeV/c )

18 S Heavy Baryon Splittings? Diquark spin alignment Hyperfine mass splitting Isospin (u, d diff.) PRL 99, 1 (7) Speaker's calc.

19 S Heavy Baryon Splittings? Diquark spin alignment (Isospin averaged) [1] Hyperfine mass splitting Isospin (u, d diff.) [] PRL 99, 1 (7) [1] Karliner, Lipkin, hepph/3743, PLB 6 (8) 539 [1] Karliner, Lipkin, arxiv:

20 X Heavy Baryon "Strangely Beautiful Baryon" "Triple Scoop Baryon" Quark content: : su : sd CDF, DØ CDF Decays weakly, dominated y quark Lifetime should e comparale to other hadrons DELPHI measured from excess of events Dimuons! ct ~ 5 cm CDF uses silicononly tracking for charged X (first time at a hadron collider) Challenging for track reco. DØ reprocesses tracks using special settings to improve effic. of highimpact parameter tracks CDF vertexing software needed modifications

21 X Heavy Baryon "Strangely Beautiful Baryon" "Triple Scoop Baryon" Quark content: : su : sd CDF, DØ CDF Decays weakly, dominated y quark Lifetime should e comparale to other hadrons DELPHI measured from excess of events Dimuons! ct ~ 5 cm CDF uses silicononly tracking for charged X Candidates / 1 MeV/c 3 1 CDF 1 L~1.9f yield=3,5±34 M=(1,31.37±.4)MeV/c M(Lp ) [GeV/c ] Events/(. GeV) DØ 1 D, 1.3 f rightsign wrongsign (a) M(Lp) [GeV]

22 X Heavy Baryon "Strangely Beautiful Baryon" "Triple Scoop Baryon" Selection: cuts on momenta, vertex quality, decay length DØ: ased on wrongsign data, signal MC CDF: use as control sample, replace K with X CDF DØ m m cm X L + m L vtx p1 1 cm p p m J/y L X + p + p + p Run 179, Event 55788, M(X ) = GeV

23 ) Candidates / (15 MeV/c X Heavy Baryon PRL 99, 5 (7) CDF 7.7s PRL 99, 151 (7) 5.5s 5.4 yield=17.5±4.3 M=(5,79.9±.5)MeV/c M(J/yX ) 1 D, 1.3 f Data Fit L~1.9f [GeV/c ] M(X ) (GeV/c ) CDF DØ DØ: many checks that no signal in wrongsign com., sideands, sideands CDF also has signal in channel DØ: lifetime consistent with expectations: Events/(.5 cm) DØ, 1.3 f Data signal Data sideand MC signal + data kgd Proper decay length (cm)

24 X Heavy Baryon X Mass DØ PRL99, 51 (7) CDF PRL99, 5 (7) Theory prediction Jenkins PRD54,4515 Karliner et al hepph/ m(x ) [GeV/c ]

25 Conclusions & Prospects Renaissance of spectroscopy (and properties) as new heavy states continue to e discovered Match of data to theory predictions for most B mesons is good; less so for the oritally excited B and B states Excellent datatheory agreement for new heavy aryons Providing useful input and comparisons to potential models, HQET, lattice gauge calculations, other QCD models: outstanding prospects for continued precision predictions (e.g., inputs for ) Next good experimental prospects? Possiility of s among others... Tevatron doing very well, expect to at least doule 1 our dataset to ~6 8 f y the end of running in 9 1

26 Conclusions & Prospects Having troule finding new names for new states (X, Y, Z...?)? MILLION