INFN – Laboratori Nazionali di Frascati Probing strong interaction at BABAR (Form factors, decay parameters, ISR) Piero Patteri INFN – Laboratori Nazionali di Frascati On behalf of the BABAR Collaboration

Selected topics probing strong interaction High precision measurement of decay parameters Angular distribution of B →(cc)K* Exclusive (C=+1) final state e+e- ® r0r0 / fr0 Transition Form Factor h, h´ at Q2 = 112 GeV2 Initial State Radiation processes pp e+e- → g + p+p- p+p- p+p- e+e- ® g + 2(p+p-) p0p0 structures e+e- ® g + KKpp Measurements of J/Y and Y(2S) decay modes Essentially dealing with two processes: the Ds+ meson FF and the study of decay amplitude, including the angular analysis, of B > ccK Moriond, March 19, 2006 Piero Patteri - LNF, INFN

Amplitude measurements with angular analysis New result !! B → (cc) K* , (cc)=J/ψ, ψ(2S), χc1 Three amplitudes + two strong phases involved Amplitude factorization of hadronic current is effective… but corrections needed when heavy quarks in final states or color suppressed modes involved More precise measurement needed to understand non factorizable contributions and select FF models (Chen and Li, PRD 71(2005)114008) Moriond, March 19, 2006 Piero Patteri - LNF, INFN

Piero Patteri - LNF, INFN Summary of results for B → (cc) K* First consistent angular analysis of the 3 charmonia BABAR measurements:Decay amplitudes and phases for each (cc) Channel J/Y K* Y(2S) K* c1 K* A0 0.556±0.009±0.010 0.48±0.05±0.02 0.77±0.07±0.04 A‼ 0.211±0.010±0.006 0.22±0.06±0.02 0.20±0.07±0.04 A┴ 0.233±0.010±0.005 0.30±0.06±0.02 0.03±0.04±0.02 d‼ -2.93±0.08±0.04 -2.8±0.4±0.1 0.0±0.3±0.1 d┴ 2.91±0.05±0.03 2.8±0.3±0.1 ----- J/ψK*: good agreement with previous measurements Preliminary results compatible with previous ones with much better precision No direct CP-violating effects with improved precision 8 s effect on strong phase Factorization predicts 0 or p Moriond, March 19, 2006 Piero Patteri - LNF, INFN

Summary of results for B → (cc) K* (II) ψ(2S) K*: Some measurements performed for the first time good agreement with CLEO (only |A0|2 measurement) χc1K*: measurement mostly comes from K+π- Results compatible with Belle (only |A0|2 measurement) First full analysis !! Synoptic of BABAR B → (cc) K* Provide data for non-factorizable contribution studies Moriond, March 19, 2006 Piero Patteri - LNF, INFN

Exclusive (C=+1) final state e+e- ® r0r0 / fr0 First observation !! Opens a new full range of possible studies Searching for exotic states, rare processes... Selecting e+e- ® 4ch. Trk @ 10.58 GeV Clean p+p- p+p- and K+K-p+p- sample Clear r (and more) signal in m(p+p-) Clear f signal in m(K+K-) On-peak data Strong rr and rf correlation found… forbidden in usual 1 VP process ! Moriond, March 19, 2006 Piero Patteri - LNF, INFN

Testing TVPA (C=+1) hypothesis rr final status ® C=+1  2 photons process involved Two Virtual Photon Annihilation process large contribution proven by cm angular distribution of r and f helicity of final r, K transverse polarization of each VP data sample: 225 fb-1  1243+/-43 rr, 147+/-13 fr BABAR preliminary BABAR preliminary Cross section calculated at |cos q*|<0.8 Moriond, March 19, 2006 Piero Patteri - LNF, INFN

h, h´ Transition Form Factors at q2=112 GeV2 (1/2) New result !! Transition Form Factor of e+e- ® g* ® h,h’g predicted in pQCD in asymptotic limit, expected s ~ a few fb Depend on h,h’ mixing ® more theoretical input needed Previous measurements only up to q2=15 GeV2 BABAR measurement close to the asymptotic limit Tight event selection and background rejection exploiting ISR expertise e+e- ® hg ® 3pg e+e- ® h´g ® 2p3g e+e- ® h´g ® 5pg Moriond, March 19, 2006 Piero Patteri - LNF, INFN

Piero Patteri - LNF, INFN h, h´ TFF at q2=112 GeV2 (2/2) New result !! BABAR measurement (full dot) at are on the boundaries of theor.l prediction bands Measured ratio h´/h=1.10+/-0.17 not compatible with theorical range 1.6-2.3 Moriond, March 19, 2006 Piero Patteri - LNF, INFN

Piero Patteri - LNF, INFN f D(S) – Previous measurements and theory additional slide evocated by introductory talk this morning ! fDs = 266 ± 32 MeV World av. From CLEO-c (BR absolute, tagged events) fD+ = 223 ± 17 +(+ 3,- 4) MeV First fDs meas. from BABAR 230.2 fb-1 on/off Y(4S) f Ds+ = 279 ± 17 ± 6 ± 19 MeV From these measurements fDs/fD = 1.25 ± 0.14 consistent with lattice calculation fDs/fD = 1.24 ± 0.07 Moriond, March 19, 2006 Piero Patteri - LNF, INFN

Initial State Radiation at BABAR: motivations and peculiarities Hadrons e+ e- ISR processes studied at B-factory yield the same observables as e+e- experiments at lower energy as a by product of operation at Y(4S). ISR equivalent luminosity 1.6 pb-1/100MeV (2GeVcm) @ 100fb-1 [Y(4S)cm] experimentally measured from topology: “hard” g + 2 charged tracks + m-ID Strong point in favor of ISR technique: weak mass and angular dependence of e DM ~1 MeV and e 0 at two-body threshold BABAR 89.3 fb-1 Moriond, March 19, 2006 Piero Patteri - LNF, INFN

e+e-→pp : the cross section New intriguing results !! e+e-→pp : the cross section Cross section parametrized by smooth (?) Electric (GE) and Magnetic (GM) Form Factors No simple theoretical interpretation of the sharp drops at 2.25 GeV, 3.0 GeV BABAR preliminary BABAR preliminary Only BABAR data collected consistently with the same detector in the range 1.875-4.5 GeV data sample: 240 fb-1 (1999-2004)

e+e-→pp : angular distribution BABAR preliminary 1.877<mpp<1.950 GeV 1.950<mpp<2.025 GeV MC histograms show separate contribution from GE (red curve) and GM (blue curve) Observed maximum at m  2 GeV/c2 (GE dominance just after threshold) evident disagreement w.r.t. previous data from PS170 experiment at Lear 2.025<mpp<2.100 GeV 2.100<mpp<2.200 GeV 2.200<mpp<2.400 GeV 2.400<mpp<3.000 GeV BABAR preliminary Moriond, March 19, 2006 Piero Patteri - LNF, INFN

Effective pp time-like form factor No old analysis disentangling GE,GM contribution due to low statistics GE = GM at Q2=4Mp2 by analyticity or s-wave dominance at threshold As in previous experiments, FF calculated assuming everywhere GE = GM Measurements very near threshold only from LEAR and BABAR Consistent observations of a steep rise toward the pp threshold BABAR preliminary BABAR preliminary Moriond, March 19, 2006 Piero Patteri - LNF, INFN

Piero Patteri - LNF, INFN BABAR data enlightening the 6 p landscape from threshold up to 4.5 GeV ! ISR photon + 6 charged hadrons 1C fit in 6p hypothesis. Cut at c2<20 ISR photon + 4 h± + 5g (Eg(ISR)>3GeV) Kaon veto applied to all charged tracks 5C fit (constrain p0 masses) BABAR preliminary BABAR preliminary Structure around 1.9 GeV, already seen by DM2 and FOCUS experiments Total systematic error ~8-10% main contribution from background subtraction (~5%) A lot of other channels under study looking for substructures (e.g. in KKpp) Moriond, March 19, 2006 Piero Patteri - LNF, INFN

Fit of e+e- ® 6p cross sections e+e- ® 3(p+p-) e+e- ® 2(p+p-) p0p0 BABAR preliminary BABAR preliminary Dip of cross section near 1.9 GeV is confirmed, but wider than in FOCUS (diffractive photoproduction) FOCUS: PL B514, 240 (2001) M = 1910  10 MeV G = 37  13 MeV M(GeV/c2) G(GeV) phase BABAR 3(p+p-) 1.88 ± 0.03 0.13 ± 0.03 20 ± 40 BABAR 2(p+p-)p0p0 1.86 ± 0.02 0.16 ± 0.02 -3 ± 15 FOCUS 3(p+p-) 1.91 ± 0.01 0.037 ± 0.013 10 ± 30 Moriond, March 19, 2006 Piero Patteri - LNF, INFN

e+e- → g + p+p- p+p- p+p-, g + p+p- p+p- p0p0 Only r found in 6 ch p Rich resonance structures in 4 ch p + 2 p0: h,w®p+p-p0 f0®p+p- f2(1270)/f0(1370)®p0p0 ? J/y® 2(p+p-) p0p0 new results !! data sample: 240 fb-1 (1999-2004) Data MC w r± Excellent sample at J/Y too ISR photon + 6 charged p h BABAR preliminary J/Y BABAR preliminary f0® p0p0 r0 Moriond, March 19, 2006 Piero Patteri - LNF, INFN

e+e- ® 2(p+p-) p0p0 structures clear w(p+p-p0) peaks in 3p mass distribution invariant mass recoiling on w®p+p-p0 w BABAR preliminary BABAR preliminary s(e+e- ® wh) (nb) Observed e+e- ® w(p+p-p0) h(p+p-p0) F(s) = 2-body P-wave phase-space Fit to a resonance shape: Found: f(1680)→wh ? BABAR preliminary J/y®wh could be PDG f(1680)? m = 1680 ± 20 MeV G0 = 150 ± 50 MeV s0 = 3.08±0.33 nb m = 1669 ± 8 MeV G0 = 123 ± 14 MeV Moriond, March 19, 2006 Piero Patteri - LNF, INFN

Improved e+e- ® KKpp with ISR Increased statistics: allows search for quasi-2-body substructures No point to point systematics and overall down 20% ® 8% Some structure expected: e+e- ® f f0 above 2000 MeV e+e- ® f f2 above 2250 MeV e+e- ® ff 0 ® K+K-p0p0 observed Mass dependance under study Additional substructures under study BABAR preliminary Moriond, March 19, 2006 Piero Patteri - LNF, INFN

Piero Patteri - LNF, INFN J/y and y(2S) decays Mode BaBar BF PDG 2004 J/y ® p+p-p0 (2.18±0.19)% (1.50±0.20)% J/y ® p+p-p+p- (3.61±0.26±0.26)´10-3 (4.0±1.0)´10-3 J/y ® K+K-p+p- (6.09±0.50±0.53)´10-3 (7.2±2.3)´10-3 J/y ® 2K+2K- (6.7 ±1.0±1.1)´10-4 --------- J/y ® 3p+3p- (4.40±0.29±0.29)´10-3 (4.0±2.0)´10-3 J/y ® 2p+2p-p0p0 (1.65±0.10±0.18)´10-2 ---------- J/y ® wh (1.47±0.41±0.15)´10-3 (1.58±0.16)´10-3 J/y ® K+K-2p+2p- (5.09 ±0.42±0.35)´10-3 (3.1±1.3)´10-3 J/y ® f2p+2p- (1.77 ±0.35±0.12)´10-3 (1.60±0.32)´10-3 J/y ® pp (2.22 ±0.16)´10-3 (2.17 ±0.08)´10-3 BES (2.10±0.12)% We actually measure BF(J/y→f)xGee Branching fractions are extracted taking Gee= (5.40±0.18) keV [PDG] NEW ! NEW ! Mode BaBar BF PDG 2004 y(2S) ® 2p+2p-p0p0 (5.3±1.6±0.6)´10-3 -------- y(2S) ® K+K-2p+2p- (2.1 ±1.0±0.2)´10-3 y(2S) ® pp (3.3 ±0.9)´10-4 (2.36 ±0.24)´10-4 NEW ! NEW ! Moriond, March 19, 2006 Piero Patteri - LNF, INFN

Piero Patteri - LNF, INFN Conclusions First measurement of e+e- producing C=+1 final states by TVPA Measurements on amplitude/phase of B → (cc) K* to test factorization correction Measurement of Transition Form Factor of e+e- → hg, h´g at q2=112 GeV2 ISR proven excellent tool to study multihadronic production < 3 GeV some advantages (2-body at th., smooth e vs. Ecm) wrt symmetric collider Best measurements of e+e- → pp Intriguing results (GE/GM>1, stepwise cross section) Confirmation of a dip in e+e- → 6 p channels at ~2 Mp Observation of e+e- → quasi 2-body final states (wh, ff0 ) e+e- → wh predominantly from a resonance at 1680 MeV (maybe a f recurrence ?) Moriond, March 19, 2006 Piero Patteri - LNF, INFN

Piero Patteri - LNF, INFN Analysis strategy Events selection: all particles detected inside a fiducial volume p/K/p discrimination using track energy loss and Cherenkov angle kinematic fit requiring: p and E conservation , mass constraint for each p0 candidate fit c2 used to select signal events and background subtraction Monte Carlo simulations used for detector acceptances, selection efficiencies and estimates of different background sources: ISR generators based on: H.Czyz et al, Eur. Phys. J. C 35(2004)527 multiple ISR soft photons: M.Caffo et al, N. C. 110A(1997)515 final state radiation: (PHOTOS) E. Barberio et al, Comp. Phys Comm. 66(1991)115 event selection for p+ p- p0 final state Moriond, March 19, 2006 Piero Patteri - LNF, INFN

Piero Patteri - LNF, INFN ISR cross section ISR Cross Section ( Born approximation for sf ) f can be a hadronic state or m+m- f c.m. energy of the radiated photon “radiator function at lowest order” photon tagging acceptance at BABAR: ~15% cross section for final state f (normalized to mmg final state) detection efficiencies corrections for final state radiation “effective c.m. energy squared” ISR equivalent luminosity Moriond, March 19, 2006 Piero Patteri - LNF, INFN

Effective form factor (another view) Steep behaviour at threshold also seen in other processes, with different quantum numbers Effective Form Factor mpp Distribution from B→ppK Arbitrary Units arbitrary units BES BaBar Possible interpretations: Tail of narrow resonances below threshold (Baryonium ?) Underestimation of the Coulomb correction factor (measure nn) ? BABAR preliminary mpp [GeV/c2] Moriond, March 19, 2006 Piero Patteri - LNF, INFN

ISR equivalent luminosity BABAR 89.3 fb-1 experimentally measured from topology: “hard” g + 2 charged tracks + m-ID equivalent e+e- luminosity 0.7 pb-1/0.1GeV @ Mmm = 1 GeV 3.6 pb-1/0.1GeV @ Mmm = 4 GeV statistically very competitive sample uniform data all-over the energy range - no systematics from point-to-point normalization limits of ISR techniques: resolution on invariant mass: (limits the width of the narrowest resonances which can be measured) J/y mass after fit s ~ 8 MeV/c2 a 1C kinematics fit (E and p conservation) improve the mass resolution (sJ/y ~ 16 MeV/c2 before fit) Moriond, March 19, 2006 GeV/c2 Piero Patteri - LNF, INFN

Amplitude measurements with angular analysis B → (cc) K* (cc)=J/ψ, ψ(2S), χc1 New result !! A tool to test factorization which: Describes meson decays assuming Decay matrix element = product of two ind. currents Factorization needs correction when Heavy quarks in final states Color suppressed modes Moriond, March 19, 2006 Piero Patteri - LNF, INFN

Piero Patteri - LNF, INFN Analysis overview Look for Ds*+ → g Ds+ → g mn signal events recoiling against fully reconstructed D0, D+ and DS+ i.e. tag event Clean sample (B → X (cc) rejected by kinematic limit) n momentum from pmiss Combine m+nm → Ds+ + g→ Ds* Essentialy it a measurement of BR od Ds -> mn /Ds ->phi pi. Events with muon recoiling against a fully reconstracted D Moriond, March 19, 2006 Piero Patteri - LNF, INFN

f Ds from Ds*+ → g Ds+ → m nm New result !! f Ds from Ds*+ → g Ds+ → m nm Decay constant is the key to calculate meson annihilation diagram in the framework of SM. Know at 1% level for light mesons Now better defined from lattice calculations then by experiments Low BR for heavy mesons due to <M> t/m/e = 10/1/2•10-5 due to helicity and PS Best experimentally accessible heavy meson pure leptonic decay channel Ds+ → m+ nm Decay parameter is the key to describe meson fenomenology in the framework of SM. Know at 1% level for light mesons... And better defined from lattice calculation then by experiment. The BR depends on opposing factors (Cabibbo suppressed in B or D to mu) Ds >mu nu best process available with closed kinematics. Moriond, March 19, 2006 Piero Patteri - LNF, INFN

Exclusive (C=+1) final state e+e- ® r0r0 / fr0 First observation !! Searching for exotic states, rare processes... Selecting e+e- ® 4ch. Trk @ 10.58 GeV Clean p+p- p+p- and K+K-p+p- sample Clear r (and more) signal in m(p+p-) Clear f signal in m(K+K-) On-peak data Moriond, March 19, 2006 Piero Patteri - LNF, INFN

Amplitude measurements with angular analysis (II) BABAR measurements: Decay amplitudes and phases Three channels each (cc) No FF model can account for every aspect, e.g. More precise measurement needed to understand non factorizable contributions and select FF model (Chen and Li, PRD 71(2005)114008) Moriond, March 19, 2006 Piero Patteri - LNF, INFN