1 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Rare B decays Introduction Hadronic two-body states - non-factorizable processes Radiative & EW penguins Special subject: B  D sJ X Youngjoon Kwon Yonsei University Overview

2 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Physics Goals in B-factories  Establish CP violation in B decays and over-constrain the SM picture of CP violation –any inconsistency?  Measure fundamental parameters of SM –10 ( out of 18, not counting neutrino masses, yet ) parameters are related with quark flavors –Belle, in particular, measures CKM triangle parameters; angles & sides  Search for rare/forbidden decays and explore new physics effects

3 Physics in Collision, June 27-29, 2004, Youngjoon Kwon The major players in B physics

4 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Clean environment of B-factories Energy difference: Beam-constrained mass: 

5 Physics in Collision, June 27-29, 2004, Youngjoon Kwon B-factory with a clean initial state n Kinematically clean environment of B production and decays n Provides an excellent laboratory to search for new particles & measure their properties –For example,B  K X(3872), K  c (2S)

6 Physics in Collision, June 27-29, 2004, Youngjoon Kwon “Rare B decays” n b  c W* is the dominant B decay process n others are suppressed due to –CKM suppression: b  u –Loop effect (“penguin”): b  s, b  d W+W+ g W+W+ V * ub

7 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Motivation for Rare B decays n SM is a very good approximation to reality. i.e., for most processes n Need to consider processes where is small in order to be sensitive to new physics. –e.g. processes dominated by penguin loops n Compare Nature (exp.) with SM prediction for those sensitive processes n Find New Physics or learn new lessons

8 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Where to look for – two starting points CPV in  Ks –Do we understand penguins? Radiative, EW BF, A CP     as an ingredient for   (  ) –Do we understand the strong- interaction part? QCDF, pQCD Color-suppressed modes Let’s start with charmless 2-meson modes and see what we can learn!

9 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Charmless 2-meson final states n Observables –BF –A CP –polarization, etc. n Experimental concerns –continuum background –hadron ID: Cherenkov + dE/dx + TOF n on interpretation –isospin, SU(3) –Final state re-scattering

10 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Discrimination of and Continuum Combine into a Fisher (or NN) Signal u,d,s,c background Fisher Discriminant Arbitrary Units Monte Carlo B produced (almost) at rest in Y(4S) frame Isotropic B Jetty Continuum

11 Physics in Collision, June 27-29, 2004, Youngjoon Kwon n cleanest modes n Both tree & penguin processes  can lead to direct CPV may provide some info. on  2 (  ) &  3 (  ) but complicated, due to hadronic effects W V ub W t g s

12 Physics in Collision, June 27-29, 2004, Youngjoon Kwon )

13 Physics in Collision, June 27-29, 2004, Youngjoon Kwon

14 Physics in Collision, June 27-29, 2004, Youngjoon Kwon T/P ratio? K0p+K0p+ p+p0p+p0 ModeCKM(f decay ) 2 RatioExp RatioBF (10 -6 ) K0+K0 K* 0  +0+ +0+ +0+ W+W+ g W+W+ V * ub

15 Physics in Collision, June 27-29, 2004, Youngjoon Kwon A CP in Belle result (152 million BB ) -

16 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Comparison w/ theory: BF & Acp ModeBF Exp (10 -6 ) BF pQCD (10 -6 ) A CP Expt (%) A CP pQCD (%) A CP QCDF (%) K+p-K+p ± – 19-9 ± 3 † -13 – ± 10 K0p+K0p ± – 26-1 ± – ± 1 K+p0K+p ± 1.18 – 140 ± 7-10 – ± 10 K0p0K0p ± 1.48 – 143 ± 37-3 ± 4 p+p-p+p ± – 1116 – 30-6 ± 13 p+p0p+p0 5.3 ± – ± ± 5 p0p0p0p ± – ± 60

17 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Longitudinal pol. in B → V V f L =  L /  100% Pol  CP even Expect: f L ~ 1 – O(M 2 V /M 2 B ) B 0   +  - N S = 93 ±22±9 BaBar [> 5  ] Cos(  1 ) M ES  

18 Physics in Collision, June 27-29, 2004, Youngjoon Kwon B      (Belle)

19 Physics in Collision, June 27-29, 2004, Youngjoon Kwon B →  and  K * [BaBar & Belle] (Errors approximated) BF (10 -6 )A CP %Long. Poln % B 0 → ρ 0 ρ 0 < 2.1 (90 % CL) B 0 → ρ + ρ - 27 ± 7 ± 699 ± 7 ± 3 B + → ρ + ρ 0 Belle 22.5 ± 5.7 ± ± 7.1 ± ± 23 ± 3 0 ± 22 ± 3 97 ± 7 ± 4 95 ± 11 ± 2 B + → ρ 0 K * ± 3.0 ± ± 32 ± 496 ± 15 ± 4 CP asymmetries are consistent with zero Longituidnal polarization is ~1 as expected  CP even

20 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Grossman-Quinn bound : Grossman Quinn bound PRD 58 (1998) BF give model-independent limits to the CP angle  |  -  Eff | < 50 o (  ) and < 20 o (  ) at 90% CL  +  - is dominantly longitudinal polarised, CP-even final state

21 Physics in Collision, June 27-29, 2004, Youngjoon Kwon A concern on G-Q bound from modifications from final-state interactions non-resonant background Let’s consider a few decay modes potentially sensitive to FSI !

22 Physics in Collision, June 27-29, 2004, Youngjoon Kwon n Not directly accessible through the spectator process n Sensitive to W-exchange, or final state rescattering  potential for generating large theory uncertainty in extracting CKM angle  3 from hadronic B decays n Wide range of predictions: (0.3 ~ 6)x10 -5

23 Physics in Collision, June 27-29, 2004, Youngjoon Kwon BF is consistent with p-QCD calculation, but in the upper edge of prediction Similar FSI amplitudes – enhanced by (uu)/(ss) – should exist for color-suppressed modes such as D 0  0, etc. 6.4  significance!

24 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Color-suppressed B decays consistently larger than the factorization model FSI re-scattering / W-exchange?

25 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Color-suppressed B decays

26 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Where to look for – two starting points CPV in  Ks –Do we understand penguins? Radiative & EW BF, A CP     as an ingredient for   (  ) –Do we understand the strong-interaction part? QCDF, pQCD Color-suppressed modes Now, let’s move on to look at the situation in the penguin sector!

27 Physics in Collision, June 27-29, 2004, Youngjoon Kwon B   K (*) Dominated by a single process (penguin)  Expect similar BF for all modes Note: BF(B  + ) < 4x10 -7 [90% CL] If large, it might indicate a large FSI Longitudinal polarisation (expected) ~1 q q s s uu B +,0  K (*)

28 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Belle

29 Physics in Collision, June 27-29, 2004, Youngjoon Kwon B   K * angular distributions

30 Physics in Collision, June 27-29, 2004, Youngjoon Kwon B   K * angular distributions

31 Physics in Collision, June 27-29, 2004, Youngjoon Kwon B   K (*) summary ModeBF (10 -6 )A CP (%)Polarisation %  K0 K0 7.6 ± ± 2.2  K+ K ± ± 1.34 ± 9 1 ± 13  K* ± ± 1.84 ± 12 7 ± 1665 ± 7 43 ± 10  K* ± ± ± ± ± 12 BaBar Belle New physics, in penguin? (Y. Grossman hep-ph/ ) Or, something new to learn in phenomenology?

32 Physics in Collision, June 27-29, 2004, Youngjoon Kwon BF(B ±  K ± ) at CDF BR (B ±   K ± ) / BR (B ±  J/  K ± ) = ± (stat.) ± (syst.) Using PDG 2002 for BR (B ±  J/  K ± ): BR (B ±   K ± ) = (6.9 ± 2.1 (stat.) ± 0.8 (syst.)) x powerful vertex trigger makes CDF a contender

Electroweak Penguins First penguin observation CLEO, PRL 1993

34 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Branching Fractions Branching Fractions (x )

35 Physics in Collision, June 27-29, 2004, Youngjoon Kwon E  spectrum in B  X s 

36 Physics in Collision, June 27-29, 2004, Youngjoon Kwon E  in B  X s   CLEO 

37 Physics in Collision, June 27-29, 2004, Youngjoon Kwon E  in B  X s  (Belle)

38 Physics in Collision, June 27-29, 2004, Youngjoon Kwon E  in B  X s  (Belle) Signal selection is optimized for max. significance in 1.8 ~ 1.9 GeV

CLEO Belle

40 Physics in Collision, June 27-29, 2004, Youngjoon Kwon CP asymmetry in B  X s  CP asymmetry is expexted to be small (<1%) in SM some non-SM models allow large (~10%) A CP without changing the BF possible contamination from X d  (A CP can be large)  but negligible in our measurement

41 Physics in Collision, June 27-29, 2004, Youngjoon Kwon CP asymmetry in B  X s 

42 Physics in Collision, June 27-29, 2004, Youngjoon Kwon A CP (B  X s  Belle tagged as ambiguous

43 Physics in Collision, June 27-29, 2004, Youngjoon Kwon A CP (B  X s  BaBar

44 Physics in Collision, June 27-29, 2004, Youngjoon Kwon A CP (B  Xs  Summary

45 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Exclusive: B  K * 

46 Physics in Collision, June 27-29, 2004, Youngjoon Kwon B  K*  asymmetries CP asymmetrySM << 0.01 Isospin asymmetrySM << (5~10)%

47 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Exclusive B  X d 

48 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Exclusive B  X d  Standard Model predictions for BF’s Prior measurements (in ) Ali & Parkhomenko (2001) Bosch & Buchalla (2001) CLEO Belle BaBar

49 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Excl. B  X d  unbinned 2D max. likelihood fit to  E and M bc Fit region: |  E| < 0.3 GeV 5.2 < M bc < 5.3 GeV

50 Physics in Collision, June 27-29, 2004, Youngjoon Kwon B  X d  fitting

51 Physics in Collision, June 27-29, 2004, Youngjoon Kwon B  X d  fitting (projections)

52 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Exclusive: B  X d  observed yield signal yield signal efficiency(%) 5.0    0.5 significance 3.5  incluing syst. err. Branching Fraction

53 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Semileptonic Penguins penguins ( , Z) and W-box contribute n sensitive to C 9, C 10 & sgn(C 7 ) ( |C 7 | from b  s  ) n rich structure –q 2 distribution –Forward-Backward asymmetry

54 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Inclusive

55 Physics in Collision, June 27-29, 2004, Youngjoon Kwon

56 Physics in Collision, June 27-29, 2004, Youngjoon Kwon 72 signal events 6.2  significance updated ( preliminary )

57 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Main features of Result is consistent with SM for both X s e + e  & X s  +   –BF, m(l + l  ), m(X s ) –Kaon yield in m(X s ) & exclusive B  Kl + l  n Will remain interesting with even more statistics –BF is sensitive to Wilson coefficients C 7, C 9 & C 10 –Detailed internal distributions m(l + l  ), A FB are sensitive to new physics

58 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Exclusive B  K (*) l + l  first observed by Belle in 2001 (29/fb) first >3  evidence by BaBar (81/fb) first observed by Belle in 2003 (140/fb)  Main backgrounds  B  J/  K (*), etc.  veto! B  K *   conversion), B  K *    m(e  e  ) > 0.14 GeV combinatorial from semileptonic, continuum B  K (*)      fake  

59 Physics in Collision, June 27-29, 2004, Youngjoon Kwon B  K (*) l + l  update

60 Physics in Collision, June 27-29, 2004, Youngjoon Kwon B  K (*) l + l -  is assumed to compensate for q 2 =0 pole for K * e  e  factor 0.75 & SM values from Ali, et al. [caution] available SM predicted values vary by factor ~2 [Note]

D sJ in B decays

62 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Observations of D sJ BaBar (Apr  PRL) –Discovery of a new resonance at 2317 MeV in CLEO (May 2003  PRD) –another resonance at 2459 MeV in

63 Physics in Collision, June 27-29, 2004, Youngjoon Kwon What’s so strange …? n Surprisingly low mass compared to the potential model expectations –below D (*) K threshold => narrow! n The masses are practically equal to those of similar states in the cu system: n Observed in the isospin-violating mode  Need to determine the quantum #’s and the BF’s

64 Physics in Collision, June 27-29, 2004, Youngjoon Kwon a potential model prediction Isgur & Wise PRL 66, 1130 (1991)

65 Physics in Collision, June 27-29, 2004, Youngjoon Kwon on the other hand... Prior to the D sJ observations, there were theoretical papers that suggested: –Nowak, Rho, & Zahed, PRD 48, 4370 (1993) –Bardeen & Hill, PRD 49, 409 (1994) In the HQ limit, the j=1/2, 0+, 1+ states could be thought of as the chiral partners of Ds and Ds*  the masses could be light

66 Physics in Collision, June 27-29, 2004, Youngjoon Kwon D sJ (2457) : new decays ( ) 1st observation  J  0

67 Physics in Collision, June 27-29, 2004, Youngjoon Kwon D sJ (2457) : new decays ( ) 1st observation  J P  0 +

68 Physics in Collision, June 27-29, 2004, Youngjoon Kwon B  D D sJ (2317) D sJ (2317)  D s   B  D D sJ (2457) D sJ (2457)  D* s   B  D D sJ (2457) D sJ (2457)  D s  D sJ production in B decays B(B  D D sJ (2317)) x B(D sJ (2317)  D s   ) = (8.5  2.0  2.6)x B(B  D D sJ (2457)) x B(D sJ (2457)  D s *   ) = (17.8  4.2  5.3) x B(B  D D sJ (2457)) x B(D sJ (2457)  D s  ) = (6.7  1.3  2.0) x 10 -4

69 Physics in Collision, June 27-29, 2004, Youngjoon Kwon D sJ (2457)  D s  decay 0.55  0.13  0.08 (continuum) 0.38  0.11  0.04 (B decays) Consistent with 1 + hypothesis, 0 +, 2 + are excluded in B  DD sJ decays

70 Physics in Collision, June 27-29, 2004, Youngjoon Kwon spin-parity of D sJ (2317) B  DD sJ is observed high J is not likely All evidence favors J P = 0 + assignment

71 Physics in Collision, June 27-29, 2004, Youngjoon Kwon spin-parity of D sJ (2457) B  DD sJ is observed high J is not likely All evidence favors J P = 1 + assignment

72 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Summary Physics in the B-factories is getting really interesting!! Rare B decays are excellent places to search for new physics and/or learn new things  A CP (B 0  K  )=-0.09  0.03  B(B 0   )=(1.9  0.5)x10-6  f L (B   K*)~0.5 « 1  color-suppressed decays Great progresses in the EW penguin processes  Precise BF, A CP & E  in B  X s   B  K (*) l + l - established; X s l + l - improved Discover/understand new states : D sJ spin-parity