New hadrons BaBar Maurizio Lo Vetere University of Genova & INFN Representing the Collaboration Particles and Nuclei International Conference October 24-28, 2005 (PANIC05)

Outline of the talk Charmonium spectroscopy –X(3870) –Y(4260) D s spectroscopy –D * sJ (2317) –D sJ (2460) –D sJ (2632) Charmed barions –  c + –  c

Charmonium spectrum States below open charm threshold well known and in agreement with potential models Most states above open charm threshold are missing. Those known have quantum numbers J PC =1 - - because are produced through virtual  in e + e - annihilation Other kind of states are possible (DD* molecules, diquark-antidiquark, hybrids)  cc  cJ hchc c’c’ ’’ DD New states discovered at B factories. Among others: X(3872), Y(4260). DD*

The X(3872) observation BABAR PRD 71, (2005) D0 PRL 93, (2004) CDF PRL 93, (2004) BELLE PRL 92, (2003) Discovered by Belle (1) in B  KX, X  J/   +  - (compatible with J/   0 ) M X = ± 0.5 MeV/c 2 slightly above D 0 D* 0 threshold  X <2.3 MeV/c 2 at 90%CL; J PC =1 ++ favoured (2) (1) PRL 91, ; (2) hep-ex/

What is the X(3872)? B  (cc)K is a typical B decay mode Isospin violating decay into J/   would be against charmonium hypothesis No state predicted at this mass Exactly at DD* threshold Possible interpretations Charmonium (1)(2) D 0 -D 0* molecule (3)(4) Diquark-antidiquark state (5) others… Need experimental result to test models: Quantum numbers, decay modes, possible charged partners (1) Barnes et all., PRD 69, (2004) (2) Eichten et all., PRD 69, (2004) (3) Swanson, PLB 588, 189 (2004) (4) Tornqvist, PLB 590, 209 (2004) (5) Maiani et all., PRD 71, (2005)

B  X(3872)K, X(3872)  J/   +  - B ±  X(3872)K ± B 0  X(3872)K s Babar preliminary 2.5  6.1  211 fb -1 More data needed to discriminate between models hep-ex/ If X(3872) is a charmonium state models predict similar production rates in B 0 and B + decays; If X(3872) is a DD* molecule, models (1) predict suppression in B 0 decays; If X(3872) is a tetra-quark: states produced in B 0 e B + decays differ and it is expected  m ~ (7 ± 2) MeV/c 2 (2) (1) Braaten and Kusunoki, PRD 71, (2005); (2) Maiani et all., PRD 71, (2005).

Search for X(3872) charged partners B 0  X - (J/  -  0 )K + B -  X - (J/  -  0 )K s PRD 71, (2005) 212 fb -1 No charged partner observed Isovectors C.L Isospin multiplet predicted by molecolar models: BR(B  X - K) ~ 2 BR(B  X 0 K) Search for B  X(3872)K, X  J/  82 fb -1 PRL 93, m(J/  ) GeV/c 2 ’’ Some models (1) predict large branching ratios (1) PLB 574, 210 No signal observed

Recoil B Inclusive charmonia in B decay B ±  X CC K ± High mass states:  c1,  ’,  ’’ and  c ’ seen Babar preliminary Recoil Mass 210 fb -1 Novel variation on the recoil technique Measurement of the K ± momentum spectrum in B center-of-mass frame No signal is observed for B +  X(3872)K + : BR(B +  X(3872)K + ) < 3.2   BR(X(3872)  J/  +  – ) >4.2%, 90% C.L. No signal is observed for charged partners in B0  X(3872) + K - : BR(B 0  X (3872) + K - )<5·10-4 at 90% C.L. Reconstructed B Y(4S) K±K± X

The Y(4260) observation No X(3872) evidence. No  (4040),  (4160),  (4415). Observed (>8  ) a broad structure Y(4260): N = 125 ± 23 M = 4259 ± MeV/c 2  = 88 ± MeV/c 2  (Y  e + e - ) · BR(Y  J/  +  - )=5.5± eV/c 2 J PC =1 -- Impossible to distinguish between 1 or more resonances. hep-ex/ Babar preliminary e + e -   ISR J/  l  l   +  fb -1  may go undetected

Search for Y(4260) in B decay Babar preliminary hep-ex/ fb -1 B ±  Y(4260)K ± ;Y(4260)  J/   +  - Excess of event observed at 4260 MeV M,  fixed to the ISR analysis values N = 128 ± 42 events Significance: 3.1  BR(B -  YK - )·BR(Y  J/  +  ) = (2.0±0.7±0.2)×10 -5 R measurements compatibility GeV  (e + e -  Y(4260)  J/   +  - )  (e + e -  hadrons) ~4% BR(Y  J/   +  -) must be high despite state above D(*)D(*) threshold

Charmonium summary X(3872) (1) –Observed in neutral and charged B decay: B  X(3872)K, X(3872)->J/  +  - –BR( X(3872)->J/  +  - 90% C.L. –No isovector charged partners observed –No X(3872)->J/  decay observed –Not seen in ISR events Y(4260) consistent with assignment J P =1 -- : –recently observed by Babar in ISR events –evidence for B ± -> Y(4260)K ± decay –statistic doesn’t allow to distinguish between one or more state hypotheses Further investigations are needed to understand the nature of these states. (1) BELLE favuor J P =1 + assignement.

New charmed mesons Four states known before B-factories data D s (1968) +, D s *(2112) +, D s1 (2536) +, D s2 *(2573) + in good agreement with theoretical predictions. Two new states discovered by BABAR (1) and CLEO (2) : D sJ *(2317) + (into D s +  0 ), D sJ (2460) + (into D s * +  0 ). Missing 0 +,1 + states? Masses significantly lower than predictions. Isospin violation decay. SELEX (3) claims a state at M= 2632 MeV decaying into D s +  and D 0 K +. (1) PRL 90, ; (2) PRD 68, ; (3) PRL 93, Other possible interpretations? tetraquark (4) or molecules (5). (4) PRD 71, ; (5) PRD 68, Quantum numbers needed

D sJ * (2317)  D s  0 and D sJ (2460)  D s *  0 Ds*ɣDs*ɣDs*ɣDs*ɣ D sJ * (2317) D sJ (2460)  D s * (D s ɣ)  0 D sJ (2460) m(D sJ * (2317))=  0.3(stat.)  0.9(syst.) MeV/c 2  0.9(syst.) MeV/c 2 (below D (*) K threshold) 123 fb -1 hep-ex/ m(D sJ (2460))=  1.3(stat.)  1.2(syst.) MeV/c 2  1.2(syst.) MeV/c 2 (below D * K threshold) D sJ (2460) D sJ * (2317) ɣ D s * ɣɣ High D s * sideband Low D s * sideband

More D sj (*) decay modes Search for radiative and dipion transitions in order to confirm or rule out some of these hypotheses D sJ (2460) D sJ * (2317) D s1 (2536) D sJ (2460) Reflections: D sJ * (2317)  D s  0 ( ɣɣ) D sJ (2460)  D s  0 ( ɣɣ ) ɣ D s +  +  - (J P =0 -,1 ,2  …) D s + ɣ (J P =1 ,2 ,…) Absence consistent with J P =0 + ; allowed for all other natural parity D sJ (2460)  D s ɣ excludes J P =O ± 123 fb -1 hep-ex/

Search for B  D (*) D sJ (*)+ 113 fb -1 hep-ex/ Side bands m(D sJ (*) ) fit results  h helicity angle for D sJ (2460)  D s . Solid line expectation for J=1, dotted line expectation for J=2. Compatible with predictions from: Bardeen et all., Phys.Rev. D68, (2003) J=1 good agreement J=2 excluded

Search for D sJ (*) isovector partners 123 fb -1 hep-ex/ D sJ * (2317) 0 D sJ * (2317) ++ Some authors * have discussed the possibility of a four quark content in D sJ states in order to explain the low mass of these states  T. Barnes, F.E.Close and H.J.Lipkin, Phys. Rev., D68, (2003)  H. J. Lipkin, Phys. Lett. B580, 50(2004)  T.E. Browder, S. Pakvasa, and A. A. Petrov, Phys. Lett. B578, 365(2004) BaBar sees no evidence for D sJ (2317) 0  D s +  - or D sJ (2317) ++  D s +  +

Search for D sJ (2632)  D s ,D 0 K +,D*K s BaBar sees no evidence for D sJ (2632)  D s , D 0 K +, D* + K s 125 fb -1 hep-ex/ D s +   (1020)  +, K * (892) 0 K + D s +   (1020)  +, K * (892) 0 K +   ɣɣ where   ɣɣ where ɣ  0  ɣɣ ɣ  0  ɣɣ ɣ  D s *+  D s + ɣ ɣ  D s *+  D s + ɣ

D sJ mesons summary D sJ * (2317) + consistent with assignment J P =0 + : –observed in D s *  0 system –not seen in D s *  or D s *  +  - D sJ * (2460) + consistent with assignment J P =1 + : –observed in D s *  0, D s + , D s *  +  - –helicity in B  D D sJ (2460) + decays consistent No evidence for isovector D sJ * (2317) + partners No evidence for D sJ * (2460) + state Evidence so far points out that D sJ may be interpreted as two ordinary cs mesons; yet the low mass of the D sJ states has still to be understood.

Backups

BaBar detector SVT: 97% efficiency – 20  m z resol SVT+DCH:  (p t )/p t =0.13%·p t +0.45% EMC:  (E)/E=2.32%·E -1/ % 1m

Experimental technique C=+1 C=-1