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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
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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
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3 Physics in Collision, June 27-29, 2004, Youngjoon Kwon The major players in B physics
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4 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Clean environment of B-factories Energy difference: Beam-constrained mass:
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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)
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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
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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
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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!
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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
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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
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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
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12 Physics in Collision, June 27-29, 2004, Youngjoon Kwon )
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13 Physics in Collision, June 27-29, 2004, Youngjoon Kwon
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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+ 111119.6 K* 0 + 11.85 0.6512.7 +0+0 2 0.660.030.275.3 +0+0 2 1.710.0850.469.1 +0+0 2 2.90.1451.3526.4 W+W+ g W+W+ V * ub
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15 Physics in Collision, June 27-29, 2004, Youngjoon Kwon A CP in Belle result (152 million BB ) -
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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- 18.2 ± 0.813 – 19-9 ± 3 † -13 – -22+5 ± 10 K0p+K0p+ 19.6 ± 1.514 – 26-1 ± 6-0.6 – -1.50 ± 1 K+p0K+p0 12.8 ± 1.18 – 140 ± 7-10 – -17+7 ± 10 K0p0K0p0 11.2 ± 1.48 – 143 ± 37-3 ± 4 p+p-p+p- 4.55 ± 0.446 – 1116 – 30-6 ± 13 p+p0p+p0 5.3 ± 0.82.7 – 4.8-7 ± 140-2 ± 5 p0p0p0p0 1.90 ± 0.470.33 – 0.6545 ± 60
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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
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18 Physics in Collision, June 27-29, 2004, Youngjoon Kwon B (Belle)
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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 ± 5.8 31.7 ± 7.1 ± 6.7 -19 ± 23 ± 3 0 ± 22 ± 3 97 ± 7 ± 4 95 ± 11 ± 2 B + → ρ 0 K *+ 10.6 ± 3.0 ± 2.420 ± 32 ± 496 ± 15 ± 4 CP asymmetries are consistent with zero Longituidnal polarization is ~1 as expected CP even
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20 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Grossman-Quinn bound : Grossman Quinn bound PRD 58 (1998) 017504 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
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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 !
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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
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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!
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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?
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25 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Color-suppressed B decays
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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!
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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 (*)
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28 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Belle
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29 Physics in Collision, June 27-29, 2004, Youngjoon Kwon B K * angular distributions
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30 Physics in Collision, June 27-29, 2004, Youngjoon Kwon B K * angular distributions
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31 Physics in Collision, June 27-29, 2004, Youngjoon Kwon B K (*) summary ModeBF (10 -6 )A CP (%)Polarisation % K0 K0 7.6 ± 1.4 9.0 ± 2.2 K+ K+ 10.0 ± 1.0 9.4 ± 1.34 ± 9 1 ± 13 K* 0 11.2 ± 1.5 10.0 ± 1.84 ± 12 7 ± 1665 ± 7 43 ± 10 K* + 12.7 ± 2.4 6.7 ± 2.216 ± 17 -13 ± 31 46 ± 12 BaBar Belle New physics, in penguin? (Y. Grossman hep-ph/0310229) Or, something new to learn in phenomenology?
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32 Physics in Collision, June 27-29, 2004, Youngjoon Kwon BF(B ± K ± ) at CDF BR (B ± K ± ) / BR (B ± J/ K ± ) = 0.0068 ±0.0021 (stat.) ± 0.0007 (syst.) Using PDG 2002 for BR (B ± J/ K ± ): BR (B ± K ± ) = (6.9 ± 2.1 (stat.) ± 0.8 (syst.)) x 10 -6 powerful vertex trigger makes CDF a contender
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Electroweak Penguins First penguin observation CLEO, PRL 1993
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34 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Branching Fractions Branching Fractions (x 10 -6 )
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35 Physics in Collision, June 27-29, 2004, Youngjoon Kwon E spectrum in B X s
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36 Physics in Collision, June 27-29, 2004, Youngjoon Kwon E in B X s CLEO
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37 Physics in Collision, June 27-29, 2004, Youngjoon Kwon E in B X s (Belle)
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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
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CLEO Belle
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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
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41 Physics in Collision, June 27-29, 2004, Youngjoon Kwon CP asymmetry in B X s
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42 Physics in Collision, June 27-29, 2004, Youngjoon Kwon A CP (B X s Belle tagged as ambiguous
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43 Physics in Collision, June 27-29, 2004, Youngjoon Kwon A CP (B X s BaBar
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44 Physics in Collision, June 27-29, 2004, Youngjoon Kwon A CP (B Xs Summary
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45 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Exclusive: B K *
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46 Physics in Collision, June 27-29, 2004, Youngjoon Kwon B K* asymmetries CP asymmetrySM << 0.01 Isospin asymmetrySM << (5~10)%
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47 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Exclusive B X d
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48 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Exclusive B X d Standard Model predictions for BF’s Prior measurements (in 10 -6 ) Ali & Parkhomenko (2001) Bosch & Buchalla (2001) CLEO Belle BaBar
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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
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50 Physics in Collision, June 27-29, 2004, Youngjoon Kwon B X d fitting
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51 Physics in Collision, June 27-29, 2004, Youngjoon Kwon B X d fitting (projections)
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52 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Exclusive: B X d observed yield 280749197 signal yield 6.315.25.9 signal efficiency(%) 5.0 0.35.9 0.44.7 0.5 significance 3.5 incluing syst. err. Branching Fraction
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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
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54 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Inclusive
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55 Physics in Collision, June 27-29, 2004, Youngjoon Kwon
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56 Physics in Collision, June 27-29, 2004, Youngjoon Kwon 72 signal events 6.2 significance updated ( preliminary )
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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
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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
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59 Physics in Collision, June 27-29, 2004, Youngjoon Kwon B K (*) l + l update
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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]
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D sJ in B decays
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62 Physics in Collision, June 27-29, 2004, Youngjoon Kwon Observations of D sJ BaBar (Apr. 2003 PRL) –Discovery of a new resonance at 2317 MeV in CLEO (May 2003 PRD) –another resonance at 2459 MeV in
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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
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64 Physics in Collision, June 27-29, 2004, Youngjoon Kwon a potential model prediction Isgur & Wise PRL 66, 1130 (1991)
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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
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66 Physics in Collision, June 27-29, 2004, Youngjoon Kwon D sJ (2457) : new decays ( ) 1st observation J 0
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67 Physics in Collision, June 27-29, 2004, Youngjoon Kwon D sJ (2457) : new decays ( ) 1st observation J P 0 +
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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 10 -4 B(B D D sJ (2457)) x B(D sJ (2457) D s * ) = (17.8 4.2 5.3) x 10 -4 B(B D D sJ (2457)) x B(D sJ (2457) D s ) = (6.7 1.3 2.0) x 10 -4
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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
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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
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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
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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
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