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1 Resolving B-CP puzzles in QCD factorization - An overview of charmless hadronic B decays - Hai-Yang Cheng Academia Sinica Based on 3 papers with Chun-Khiang Chua B-CP puzzles in QCDF B u,d decays B (K,K *,K 0 *,K 2 * )( , ’) May 6, 2010 at NTHU
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Day in the life – The Emperor’s Tea : Murayama
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3 Direct CP asymmetries =A CP (K - ) – A CP (K - ) K - K - K *0 K - A CP (%)-9.8 +1.2 -1.1 38 614.8 2.8 -37 9 19 5 37 11 -13 4 S 8.5 6.3 5.3 4.1 3.8 3.4 3.3 K* - K - K - A CP (%) -18 7 15 6 5.0 2.5 -13 7 43 +25 -24 11 6 S 2.6 2.5 2.0 1.9 1.8 CDF: A CP (B s K + )=0.39 0.17 (2.3 )
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4 In heavy quark limit, decay amplitude is factorizable, expressed in terms of form factors and decay constants. Encounter several difficulties: Rate deficit puzzle: BFs are too small for penguin-dominated PP,VP,VV modes and for tree-dominated decays , CP puzzle: CP asymmetries for K - , K *- , K - , are wrong in signs Polarization puzzle: f T in penguin-dominated B VV decays is too small 1/m b power corrections !
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5 A(B 0 K - + ) u a 1 + c (a 4 c +r a 6 c ) Theory Expt Br 13.1x10 -6 (19.4 0.6)x10 -6 A CP 0.04 -0.098 +0.012 -0.011 Im 4 c 0.013 wrong sign for A CP penguin annihilation charming penguin, FSI penguin annihilation 1/m b corrections 4c4c
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6 has endpoint divergence: X A and X A 2 with X A 1 0 dy/y Adjust and to fit BRs and A CP 1.10, -50 o Im( c + c ) -0.039 Beneke, Buchalla, Neubert, Sachrajda
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77 New CP puzzles K - K - K *0 K - A CP (%)-9.8 +1.2 -1.1 38 614.8 2.8 -37 9 19 5 37 11 -13 4 S 8.5 6.3 5.3 4.1 3.8 3.4 3.3 m b 3.3 PA ( 1.9) K* - K - K - A CP (%) -18 7 15 65.0 2.5 -13 7 43 +25 -24 11 6 S 2.6 2.5 2.0 1.9 1.8 m b PA Penguin annihilation solves CP puzzles for K - , ,…, but in the meantime introduces new CP puzzles for K - , K *0 , … Also true in SCET with penguin annihilation replaced by charming penguin
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All “problematic” modes receive contributions from c’=C’+P’ EW. T’ a 1, C’ a 2, P’ EW (-a 7 +a 9 ), P’ c EW (a 10 +r a 8 ), t’=T+P’ c EW A K puzzle is resolved, provided c’/t’ ~ 1.3-1.4 with a large negative phase (naively, |c’/t’| 0.9) a large complex C’ or P’ EW A K 0 if c’ is negligible Large complex C’: Charng, Li, Mishima; Kim, Oh, Yu; Gronau, Rosner; … Large complex P’ EW needs New Physics for new strong & weak phases Yoshikawa; Buras et al.; Baek, London; G. Hou et al.; Soni et al.; Khalil et al.
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9 Power corrections have been systematically studied by Beneke, Neubert: S2, S4 Ciuchini et al., 0801.0341 Duraisamy & Kagan, 0812.3162 Li & Mishima, 0901.1272 The two distinct scenarios can be tested in tree-dominated modes where P EW <<C. CP puzzles of , & large rates of , cannot be explained by a large P EW
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10 a 2 a 2 [1+ C exp(i C )] C 1.3, C -70 o for PP modes a 2 (K ) 0.51exp(-i58 o ) Two possible sources: spectator interactions NNLO calculations of V 2 & H 2 are now available Real part of a 2 comes from H and imaginary part from vertex a 2 ( ) 0.33 - 0.09i =0.34 exp(-i15 o ) for = 250 MeV a 2 (K ) 0.51exp(-i58 o ) = 4.9 & -77 o [Bell, Pilipp] final-state rescattering [ C.K. Chua] Neubert: In the presence of soft FSIs, there is no color suppression of C w.r.t. T
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11 K - K - K *0 K - A CP (%)-9.8 +1.2 -1.1 38 6 14.8 2.8 -37 9 19 5 37 11 -13 4 S 8.5 6.3 5.3 4.1 3.8 3.4 3.3 m b 3.3 PA ( 1.9) large complex a 2 K* - K - K - A CP (%) -18 7 15 6 5.0 2.5 -13 7 43 +25 -24 11 6 S 2.6 2.5 2.0 1.9 1.8 m b PA large complex a 2 All new CP puzzles are resolved !
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12 B - K - A(B 0 K - + ) = A K ( pu 1 + 4 p + 3 p )= t’+p’ 2 A(B - K - 0 ) = A K ( pu 1 + 4 p + 3 p )+A K ( pu 2 +3/2 3,EW p )= t’+p’+c’ m b penguin ann large complex a 2 Expt A CP (K- )(%) 7.3 -5.5 4.9 +5.9 -5.8 5.0 2.5 A K (%) 3.3 1.9 12.3 +3.0 -4.8 14.8 2.8 In absence of C’ and P’ EW, K - and K - have similar CP violation = a 1, = a 2 arg(a 2 )=-58 o
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13 Br(B PP) Large K ’ rates are naturally accounted for in QCDF partial NLO A =1.10 A = -50 o C =1.3 C = -70 o
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14 B K (*) K ’ In q & s flavor basis ( q =(uu+dd)/√2, s =ss) =39.3 BRs in units of 10 -6 Interference between (b) & (c) K ’ K For K *, (b) is governed by a 4 -r a 6, (c) by a 4 ; a 4, a 6 are negative and |a 4 |< |a 6 |; chiral factor r is of order unity additional sign difference between (b) & (c) for K * (‘)
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15 A CP (B PP)(%) Several SCET predictions are in conflict with experiment
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16 B 0 K 0 A(B - K 0 - ) = A K ( 4 p + 3 p ) = p’ 2 A(B 0 K 0 0 ) = A K (- 4 p - 3 p ) + A K ( pu 2 + pc 3/2 3,EW c ) = -p’+c’ In absence of C’ and P’ EW, K 0 and K 0 have similar CP violation CP violation of both K 0 & K 0 is naively expected to be very small A’ K =A CP (K 0 ) – A CP (K 0 ) = 2sin Imr C +… - A K m b penguin ann large complex a 2 Expt A CP (K 0 )(%) -4.0 0.75 -10.6 +6.2 -5.7 -1 10 A’ K (%) -4.7 0.57 -11.0 +6.1 -5.7 -- BaBar: -0.13 0.13 0.03, Belle: 0.14 0.13 0.06 for A CP (K 0 ) A CP (K 0 )= -0.15 0.04 A CP (K 0 )=-0.073 0.041 An observation of A CP (K 0 ) - (0.10 0.15) power corrections to c’ Toplogical quark diagram approach A CP (K 0 )= -0.08 -0.12
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17 B - K - Destructive interference penguin amp is comparable to tree amp more sizable CP asymmetry in K than K ’ Although f c =-2 MeV is very small compared to f q = 107 MeV, f s = -112 MeV, it is CKM enhanced by V cb V cs * /(V ub V us * ) m b penguin annlarge complex a 2 (w/o charm) large complex a 2 (with charm) Expt A CP (K - )(%) -23.3 12.7 -2.0 -14.5 -37 9 A CP ( )(%) -11.4 11.4 -5.0 -13 7 Charm content of plays a crucial role for ACP(K - ), but not for A CP ( ) Prediction of A CP (K - ) still falls short of data
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18 pQCD prediction is very sensitive to m qq, mass of q A CP (K - ) = 0.0562, 0.0588, -0.3064 for m qq = 0.14, 0.18, 0.22 GeV Two issues: (i) with anomaly: (ii) stability w.r.t. m qq Akeroyd,Chen,Geng Xiao et al. (0807.4265) reply on NLO corrections to get a correct sign: A CP (K - )= 0.093 to LO, (-11.7 +8.4 -11.4 )% at NLO 1). If NLO effects flip the sign of A CP, pQCD calculations should be done consistently to NLO 2). Missing parts of NLO: hard spectator & weak annihilation
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19 Time-dependent CP asymmetries: S B PP QCDF prediction for S( ) agrees well with data S( ’K S ) is theoretically very clean in QCDF & SCET but not so in pQCD Around 2005, CCS and Beneke got S( ’K S ) 0.74 in QCDF. Why 0.67 this time ?
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20 sin2 extracted from charmonium data is 0.725 circ 2005, and 0.672 0.023 today. It is more sensible to consider the difference S f = - f S f - sin2 S f = 2|r f |cos2 sin cos f with r f =( u A f u )/( c A f c ) small and could be + or – S Ks positive
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21 B VV decays Branching fractions tree-dominated decays: VV>PV>VP>PP (due to f V > f P ) penguin-dominated decays: PP>PV~VV>VP (due to amplitudes a 4 +r P a 6, a 4 +r V a 6, a 4 -r P a 6, a 4 +r V a 6 Polarization puzzle in charmless B→VV decays Why is f T so sizable ~ 0.5 in B → K * Á decays ? In transversity basis
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22 A 00 >> A -- >> A ++
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23 B → K * Á ® 3 =a 3 +a 5, ® 4 =a 4 -r  Á a 6, ® 3,EW =a 9 +a 7, ¯ 3 = penguin ann h=0 h= - h=0 h= - Coefficients are helicity dependent ! constructive (destructive) interference in A - (A 0 ) ⇒ f L ¼ 0.58 with ¯ 3 =0 NLO corrections alone can lower f L and enhance f T significantly ! Yang, HYC
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24 Although f L is reduced to 60% level, polarization puzzle is not resolved as the predicted rate, BR» 4.3£10 -6, is too small compared to the data, » 10£10 -6 for B →K * Á Br & f L are fitted by ½ A =0.60, Á A = -50 o Kagan f || ¼ f ? » 0.25 (S-P)(S+P) (S-P)(S+P) penguin annihilation contributes to A -- & A 00 with similar amount
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25 =0.78, =-43 o for K * , =0.65, =-53 o for K * Rate for is very small However, pQCD prediction is larger than QCDF by a factor of 20 ! Br(B 0 K *0 K *0 )=1.28 +0.35 -0.30 0.11 by BaBar, 0.3 0.3 0.1 by Belle Br(B 0 )=0.9 +1.5+2.4 -2.6-1.5 is obtained with C =0 soft corrections to a 2 are large for PP, moderate for VP and very small for VV r V <<r P doesn’t help! or due to Goldstone nature of the pion ? [Duraisamy, Kagan]
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26 Conclusions In QCDF one needs two 1/m b power corrections (one to penguin annihilation, one to color-suppressed tree amplitude) to explain decay rates and resolve CP puzzles. CP asymmetries are the best places to discriminate between different models.
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27 ’ is the other way around
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28 Spare slides
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29 Br(B VP) A (VP)=1.07 A (VP)= -70 0 A (PV)=0.87 A (PV)= -30 o A (K )=0.70 A (K )= -40 o C =0.8 C = - 70 o Br(B - )=Br(B - ) sin is an - mixing angle 3.3 o Belle: C.C. Chiang
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30 Br(B VP) A (VP)=1.09 A (VP)= -70 0 A (PV)=0.87 A (PV)= -30 o A (K )=0.70 A (K )= -40 o C =0.8 C = - 70 o In heavy quark limit, K* rates are too small by (15 50)%, while K are too small by a factor of 2 3 ( K * )> ( K * ) QCDF predictions for K* ’ too small compared to BaBar but consistent with Belle: Br(K *- ’)<2.9, Br(K *0 ’)<2.6
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31 A CP (B VP)(%) K *0 -, - K 0 have small A CP as they are pure penguin processes A K* =A CP (K *- ) - A CP (K *- )= -2sin Imr c (K * )+…. 0.137 A’ K * =A CP (K *0 )- A CP (K *0 )= 2sin Imr c (K * ) +… -0.111 Data of A CP (K *0 ) is in better agreement with QCDF than pQCD & SCET. The SCET predictions are ruled out by experiment.
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32 S B VP S B VP S is negative and sensitive to soft corrections on a 2 Expt’l errors of S are very large
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33 is expected to have larger f T as its tree contribution is small b d penguin-dominated modes K *0 K *0, K *0 K *- are expected to have f L 0.5. Experimentally, f L 0.75-0.80 (why ?) For K *- 0, recent BaBar measurement gives f L =0.9 0.2 with 2.5 significance QCDF leads to
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