Some Recent Results. Jack Ritchie University of Texas at Austin (representing the BABAR collaboration) Progress on Rare FCNC B decays

Transcription

1 Some Recent Resuts from AAR University of Texas at Austin (representing the AAR coaboration) Progress on Rare FCNC decays Miami 010

2 Outine I. The AAR Experiment II. Rare FCNC Decays i. b sγ ii. b dγ (incuding 0 γγ) iii. b s (where = e,μ,τ orν) III. Concusion Miami 010

3 e + e γ * production at PEP-II ϒ(4S) + ee Υ(4 S) ϒ(4S) decays 100% to (50% +, 50% 0 0 ) 1.10 Υ(1S) σ(e + e hadrons) (nb) 100 M Υ(S) AAR Dataset Υ(3S) Mass (GeV) threshod 10 M 460 M (430 fb 1 ) Υ(4S) Rich program incuding CPV, CKM parameters, rare decays, charm, τ decays, bottomonium, > 450 pubications so far Continuum (uʉ, dd, ss, cc, τ + τ ) events are backgrounds to most decay measurements. Miami 010 3

4 AAR at SLAC CM boost βγ GeV e, 3.1 GeV e T soenoid Siicon vertex tracker 5 ayer, doube-sided Drift chamber Tracking + de/dx 40 stereo ayers DIRC partice ID Quartz bars, PMTs CsI(T) caorimeter 6580 crystas Instrumented Fux Return Iron + resistive pate chambers and imited streamer tubes Miami 010 4

5 b sγ in the Standard Mode First penguin 1993 CLEO observation of K*γ Heavy-quark hadron duaity X sγ ) b sγ ) Theoreticay cean prediction in the Standard Mode Next-to-next-eading order (NNLO) cacuation (E γ > 1.6 GeV) Sma (7%) SM theory uncertainty constraint on New Physics E γ spectrum refects b quark s mass, Fermi motion and guon brem Input to shape function parameters for V ub from b u ν endpoint and used in extraction of V cb from b c ν X s γ ) = (3.15 ± 0.3) 10 t quark dominates 4 Misiak et a., PRL 98, 000(007) Miami 010 5

6 New Physics in b sγ Sensitive to new heavy partices in the oops charged Higgs, superpartners, etc Leading-order and next-to-eading order cacuations for many modes M H ± > 95 GeV Experiment vs theory F strong constraints on New Physics -Higgs doubet mode (type II); (as in MSSM) Haisch, arxiv: Miami 010 6

7 Experimenta Issues for X s γ Two experimenta techniques Fuy Incusive Ony ook at the γ from the signa decay Continuum rejection via event shape and either epton tag (rejection ~10 5 for.5% signa eff) or reconstructing the other E γ mb m m b s m b Semi-incusive (sum of excusive modes) Reconstruct many fina states (38 in AAR) Dominant systematic from the missing fraction ( 45%) Suppress backgnd with E γ min cut Compromise between experimenta vs theoretica uncertainties Fuy incusive, after continuum cuts AAR MC E min cut ackground must be subtracted. Miami 010 7

8 Experimenta Issues for X s γ Two experimenta techniques Fuy Incusive Ony ook at the γ from the signa decay Continuum rejection via event shape and either epton tag (rejection ~10 5 for.5% signa eff) or reconstructing the other Semi-incusive (sum of excusive modes) Reconstruct many fina states (38 in AAR) Dominant systematic from the missing fraction Suppress backgnd with E γ min cut Compromise between experimenta vs theoretica uncertainties E γ mb m m b s m AAR Preiminary bind signa region b Miami 010 8

9 Experimenta Status for X s γ Comparison of measurements extrapoated to E γ >1.6 GeV by the Heavy Favor Averaging Group. Updates are in progress for these aar measurements. Miami 010 9

10 Direct CP Vioation (A CP ) in X s γ A CP = Γ( Γ( X X s+ d s+ d γ ) Γ( γ ) + Γ( X X s + d s + d γ ) γ ) 0 A strong SM prediction, so a good NP test. Lepton tag reco AAR Preiminary Lepton tag ± ± optimized region.1<e γ <.8 GeV Miami

11 b dγ Suppressed w.r.t. b sγ by V td /V ts ( 0.04) Sensitivity to New Physics via oops CKM suppression may not hod Compementary to s and d mixing for determining V td /V ts Less precise, but Possibe different sensitivity to New Physics in box (mixing) vs radiative penguin diagrams. V td /V ts determination can be based on excusive ratio Depends on ratio of form factors Ratio of incusive rates is theoreticay ceaner AAR has recenty reported a semi-incusive measurement ρ γ ) K * γ ) Miami

12 Seven modes with one π K X d/s γ Pus CC states M ES ΔE = = E E * * beam E * beam p * Signa peaks at M ES = M ΔE = 0 Hadronic mass bins: GeV (a ρ,ω; K*) GeV (nonresonant) sγ Continuum rejection via event shape (neura net) 99% rejection with good signa eff ( 5%) Extract signas via -d maximum ikeihood fits Correct for missing modes Simpe in ow-mass bin; mosty missing K 0 modes Fragmentation mode for highmass (dominant systematic error) 4.8σ dγ Miami < M X <.0 GeV 1

13 X d/s γ Resuts Correct to fu M x range using Kagan-Neubert spectrum (ratio insensitive) Convert to V td /V ts using method of Ai et a, Phys Lett 49, 87(1998) V td / V ts = ± 0.0(stat) ± 0.04(syst) ± 0.00(th) arxiv: Miami

14 Search for 0 γγ Annihiation penguin Leading order Standard Mode cacuation 0 γγ ) = ( ) Possibe enhancement from New Physics in oop Never observed, best prior imit from ee New AAR search based on 430 fb 1 (fu dataset) Simpe signature, but significant backgrounds from π 0 and η decays in continuum events 10 8 osch and uchaa, JHEP 008:054(00) 0 7 γγ ) < (90% CL) PRD 73,051107(006) Miami

15 0 γγ ackground Rejection Most rejection from ikeihood ratios (π 0,η)and neura net Event shape inputs m γγ and E γ inputs LR = P ( m P, E sig γγ bkg γ ( m γγ, E ) + P bkg γ ) ( m γγ, E γ ) Net rejection ~10 3 for cuts with 7% signa efficiency Miami

16 AAR Preiminary 0 γγ Resuts N signa = events (1.9σ) 0.30 ΔE 0.13 GeV Set imit by integrating ikeihood function to 90% smeared by 1% systematic error M ES > 5.7 GeV 90% CL upper imit Miami

17 C C eff C 7 eff 9 eff 10 vector axia vector b s + More compex than b s γ - W-box and Z-penguin ampitudes important -cc resonances in diepton spectrum (removed by cuts on M ) More observabes q = M - diepton mass spectrum ( ) - forward backward asymmetry (A F ) - New Physics may induce arge effects in these observabes Standard Mode estimates made at NNLO - Reiabe for incusive b s + - Form factor uncertainties affect excusive processes = e,μ Miami

18 b s + = e,μ eff C 7 H χ uà,cà,tà More compex than b s γ - W-box and Z-penguin ampitudes important -cc resonances in diepton spectrum (removed by cuts on M ) C C eff 9 eff 10 vector axia vector H H uà,cà,tà χ uà,cà,tà χ + More observabes q = M - diepton mass spectrum ( ) - forward backward asymmetry (A F ) - New Physics may induce arge effects in these observabes Standard Mode estimates made at NNLO - Reiabe for incusive b s + - Form factor uncertainties affect excusive processes Miami

19 b s + Experimenta Issues = e,μ Fuy incusive measurements not possibe Semi-incusive anaysis via sum of excusive states (K + +nπ) Excusive K + and K* + easier, but invove form factors Interference from K ( ) J/ψ and K ( ) ψ(s) Remove with cuts on + mass Provide important contro sampes (same topoogy, known Fs) Main backgrounds from and D semieptonic decays Suppress using event shape, vertex info, missing energy kg from Dπ (D K ( ) π ) + π μ mis-id Veto K ( ) π mass cose to D Extract signa with maximum ikeihood fits X s + J/ψ ψ(s) AAR 349 fb -1 K* + 0.1< q < 6.5 GeV / b Miami q m

20 b s + ranching Fraction Summary = e,μ Good agreement between experiment and Standard Mode theory Experimenta errors smaer than theory errors for excusive modes With current statistics, a F vs q measurements consistent with SM Semi-incusive measurements not updated to fu datasets (yet) Miami 010 0

21 A F in b s + Lepton forward backward asymmetry (A F ) backward forward θ μ μ + Lepton pair CM A q 1 d ) = d d cos θ sng(cos θ ) dq d cos θ F ( dq Sensitive to interference effects due to New Physics that might not affect Fs - e.g., reative signs of Wison coefficients A F C 7 = C 7 (SM) Standard Mode C 7 = C 7 (SM) C 9 C 10 = C 9 C 10 (SM) C 9 C 10 = C 9 C 10 (SM) Miami 010 1

22 A F in K* + Lepton forward backward asymmetry (A F ) backward forward θ μ μ + Lepton pair CM A q 1 d ) = d d cos θ sng(cos θ ) dq d cos θ F ( dq 0.1< q < 6.5 GeV q >10.4 GeV A F determined from ML fit - Aong with K poarization (F L ) - Fit vaidation with K J/ψ and K ψ(s) AAR 349 fb -1 Miami 010

23 A F Measurements in K* + - ee 605 fb -1 AAR 349 fb -1 C 7 = C 7 (SM) Standard Mode q (GeV /c ) Experiments are consistent Consistent with SM Tend to be high at ow q AAR resut wi be updated to fu data + other improvements Ceary need higher statistics Miami 010 3

24 Search for KνÅ Standard Mode branching fraction 4 x 10 6 Sensitive to mutipe New Physics scenarios Significant enhancements possibe (MSSM, unpartices, extra dimn); Yamada, PRD 77,01405; Aiev JHEP 07:07; Coangeo PRD 73, New search using fu aar dataset Reconstruct tag in D ( ) ν K ± or K s Decision trees for bkgnd rejection Missing energy, event info kinematics, Tag info 6 (38) inputs for K + (K 0 ) mode Miami 010 4

25 Search for KνÅ SM from uchaa et a, PRD 63, (001) N sig at SM F.9 ± ± 0.1 AAR preiminary + + K νν ) < x10 5 AAR preiminary 0 0 K ν ν ) < x10 4 Miami 010 5

26 First Search for Kτ + τ J/ψ ψ(s) q > = ( pυ ptag p K ) 0.6mb τ eνν τ μνν τ πν Hewett, PRD 53,4964(1996) SM rate inaccessibe, but X s =K 50% NP may enhance, (m τ /m μ ) =80 Hier, PRD 70, (004) Important to identify experimenta issues/prospects for future expts AAR Preiminary (43 fb 1 ) ackground est Observe 47 events with 65±7 est bkg 3 charged tracks (1K ± ) + missing energy Miami K τ τ ) < % CL 3

27 Summary/Concusions There has been ots of progress, and continues to be ots of activity, in the study of rare FCNC decays The fow of resuts from AAR (and ee) wi continue as fina anayses are competed over the next year or two. These processes are important Reiabe Standard Mode cacuations possibe Sensitive to New Physics through oops No current resut is inconsistent with the SM Severa key measurements are statisticay imited, so a compete study of these processes wi require much arger data sampes. Miami 010 7

28 ackup/extra Sides Miami 010 8

29 Isospin Asymmetry A I = 0 0 K K (*)0 (*)0 + + τ 0 ) τ + τ 0 ) + τ + ± ± K K (*) ± (*) ± + + ) ) Fedman and Matias, JHEP 0301,074(003) Expected near 0 for a q Measurements Consistent with 0 at high q Favor ess than 0 at ow q ee.σ beow 0 AAR 3.9σ beow 0 Miami 010 9

30 Direct CP Asymmetry A I = K K (*) (*) + + ) ) + K K (*) (*) + + ) ) Test for direct CP vioation; ess than 1% in Standard Mode Miami

31 Lepton Favor Asymmetry K K + μ μ ) + e e ) (*) R K (*) = (*) 1 in SM (for K* if q >0.1 GeV) Enhanced in modes with two-higgs doubets, incuding SUSY with a neutra Higgs at arge tan β Miami