Measurement of the Forward-Backward Asymmetry in the <em>B -&gt; K(*)μ⁺μ⁻</em> Decay and First Observation of the <em>B_s⁰ -&gt; ϕμ⁺μ⁻</em> Decay

Article

Reference

Measurement of the Forward-Backward Asymmetry in the B -> K(*)μ

+

μ

Decay and First Observation of the B

-> ϕμ

μ

Decay

CDF Collaboration

CLARK, Allan Geoffrey (Collab.), et al.

Abstract

We reconstruct the rare decays B+→K+μ+μ−, B0→K*(892)0μ+μ−, and B0s→ϕ(1020)μ+μ− in a data sample corresponding to 4.4  fb−1 collected in pp collisions at s√=1.96  TeV by the CDF II detector at the Tevatron Collider. Using 121±16 B+→K+μ+μ− and 101±12 B0→K*0μ+μ−

decays we report the branching ratios. In addition, we report the differential branching ratio and the muon forward-backward asymmetry in the B+ and B0 decay modes, and the K*0 longitudinal polarization fraction in the B0 decay mode with respect to the squared dimuon mass. These are consistent with the predictions, and most recent determinations from other experiments and of comparable accuracy. We also report the first observation of the B0s→ϕμ+μ− decay and measure its branching ratio BR(B0s→ϕμ+μ−)=[1.44±0.33±0.46]×10−6 using 27±6 signal events. This is currently the most rare B0s decay observed.

CDF Collaboration, CLARK, Allan Geoffrey (Collab.), et al . Measurement of the

Forward-Backward Asymmetry in the B -> K(*)μ

μ

Decay and First Observation of the B

->

ϕμ

μ

Decay. Physical Review Letters , 2011, vol. 106, no. 16, p. 161801

DOI : 10.1103/PhysRevLett.106.161801

Available at:

http://archive-ouverte.unige.ch/unige:38678

Disclaimer: layout of this document may differ from the published version.

1 / 1

Measurement of the Forward-Backward Asymmetry in the B ! K

Decay and First Observation of the B

!

Decay

T. Aaltonen,²²B. A´ lvarez Gonza´lez,^10,wS. Amerio,^42aD. Amidei,³³A. Anastassov,³⁷A. Annovi,¹⁸J. Antos,¹³ G. Apollinari,¹⁶J. A. Appel,¹⁶A. Apresyan,⁴⁷T. Arisawa,⁵⁶A. Artikov,¹⁴J. Asaadi,⁵²W. Ashmanskas,¹⁶B. Auerbach,⁵⁹ A. Aurisano,⁵²F. Azfar,⁴¹W. Badgett,¹⁶A. Barbaro-Galtieri,²⁷V. E. Barnes,⁴⁷B. A. Barnett,²⁴P. Barria,^45c,45aP. Bartos,¹³ M. Bauce,^42b,42aG. Bauer,³¹F. Bedeschi,^45aD. Beecher,²⁹S. Behari,²⁴G. Bellettini,^45b,45aJ. Bellinger,⁵⁸D. Benjamin,¹⁵ A. Beretvas,¹⁶A. Bhatti,⁴⁹M. Binkley,^16,aD. Bisello,^42b,42aI. Bizjak,^29,ccK. R. Bland,⁵C. Blocker,⁷B. Blumenfeld,²⁴

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S. Zucchelli^6b,6a (CDF Collaboration)

1Institute of Physics, Academia Sinica, Taipei, Taiwan 11529, Republic of China

2Argonne National Laboratory, Argonne, Illinois 60439, USA

3University of Athens, 157 71 Athens, Greece

4Institut de Fisica d’Altes Energies, Universitat Autonoma de Barcelona, E-08193, Bellaterra (Barcelona), Spain

5Baylor University, Waco, Texas 76798, USA

6aIstituto Nazionale di Fisica Nucleare Bologna, I-40127 Bologna, Italy

6bUniversity of Bologna, I-40127 Bologna, Italy

7Brandeis University, Waltham, Massachusetts 02254, USA

8University of California, Davis, Davis, California 95616, USA

9University of California, Los Angeles, Los Angeles, California 90024, USA

10Instituto de Fisica de Cantabria, CSIC-University of Cantabria, 39005 Santander, Spain

11Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA

12Enrico Fermi Institute, University of Chicago, Chicago, Illinois 60637, USA

13Comenius University, 842 48 Bratislava, Slovakia; Institute of Experimental Physics, 040 01 Kosice, Slovakia

14Joint Institute for Nuclear Research, RU-141980 Dubna, Russia

15Duke University, Durham, North Carolina 27708, USA

16Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA

17University of Florida, Gainesville, Florida 32611, USA

18Laboratori Nazionali di Frascati, Istituto Nazionale di Fisica Nucleare, I-00044 Frascati, Italy

19University of Geneva, CH-1211 Geneva 4, Switzerland

20Glasgow University, Glasgow G12 8QQ, United Kingdom

21Harvard University, Cambridge, Massachusetts 02138, USA

22Division of High Energy Physics, Department of Physics, University of Helsinki and Helsinki Institute of Physics, FIN-00014, Helsinki, Finland

23University of Illinois, Urbana, Illinois 61801, USA

24The Johns Hopkins University, Baltimore, Maryland 21218, USA

25Institut fu¨r Experimentelle Kernphysik, Karlsruhe Institute of Technology, D-76131 Karlsruhe, Germany

26Center for High Energy Physics: Kyungpook National University, Daegu 702-701, Korea; Seoul National University, Seoul 151-742, Korea; Sungkyunkwan University, Suwon 440-746, Korea; Korea Institute of Science

and Technology Information, Daejeon 305-806, Korea; Chonnam National University, Gwangju 500-757, Korea;

Chonbuk National University, Jeonju 561-756, Korea

27Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA

28University of Liverpool, Liverpool L69 7ZE, United Kingdom

29University College London, London WC1E 6BT, United Kingdom

30Centro de Investigaciones Energeticas Medioambientales y Tecnologicas, E-28040 Madrid, Spain

31Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA

161801-2

32Institute of Particle Physics: McGill University, Montre´al, Que´bec, Canada H3A 2T8;

Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6; University of Toronto, Toronto, Ontario, Canada M5S 1A7; and TRIUMF, Vancouver, British Columbia, Canada V6T 2A3

33University of Michigan, Ann Arbor, Michigan 48109, USA

34Michigan State University, East Lansing, Michigan 48824, USA

35Institution for Theoretical and Experimental Physics, ITEP, Moscow 117259, Russia

36University of New Mexico, Albuquerque, New Mexico 87131, USA

37Northwestern University, Evanston, Illinois 60208, USA

38The Ohio State University, Columbus, Ohio 43210, USA

39Okayama University, Okayama 700-8530, Japan

40Osaka City University, Osaka 588, Japan

41University of Oxford, Oxford OX1 3RH, United Kingdom

42aIstituto Nazionale di Fisica Nucleare, Sezione di Padova-Trento, I-35131 Padova, Italy

42bUniversity of Padova, I-35131 Padova, Italy

43LPNHE, Universite Pierre et Marie Curie/IN2P3-CNRS, UMR7585, Paris, F-75252 France

44University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA

45aIstituto Nazionale di Fisica Nucleare Pisa, I-56127 Pisa, Italy

45bUniversity of Pisa, I-56127 Pisa, Italy

45cUniversity of Siena, I-56127 Pisa, Italy

45dScuola Normale Superiore, I-56127 Pisa, Italy

46University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA

47Purdue University, West Lafayette, Indiana 47907, USA

48University of Rochester, Rochester, New York 14627, USA

49The Rockefeller University, New York, New York 10065, USA

50aIstituto Nazionale di Fisica Nucleare, Sezione di Roma 1, I-00185 Roma, Italy

50bSapienza Universita` di Roma, I-00185 Roma, Italy

51Rutgers University, Piscataway, New Jersey 08855, USA

52Texas A&M University, College Station, Texas 77843, USA

53aIstituto Nazionale di Fisica Nucleare Trieste/Udine, I-34100 Trieste, I-33100 Udine, Italy

53bUniversity of Trieste/Udine, I-33100 Udine, Italy

54University of Tsukuba, Tsukuba, Ibaraki 305, Japan

55Tufts University, Medford, Massachusetts 02155, USA

56Waseda University, Tokyo 169, Japan

57Wayne State University, Detroit, Michigan 48201, USA

58University of Wisconsin, Madison, Wisconsin 53706, USA

59Yale University, New Haven, Connecticut 06520, USA (Received 6 January 2011; published 18 April 2011)

We reconstruct the rare decaysB^þ!K^þþ,B⁰!Kð892Þ^0þ, andB⁰s!ð1020Þ^þin a data sample corresponding to4:4 fb¹collected inppcollisions at ffiffiffi

ps

¼1:96 TeVby the CDF II detector at the Tevatron Collider. Using12116 B^þ!K^þþ and10112 B⁰!K^0þ decays we report the branching ratios. In addition, we report the differential branching ratio and the muon forward- backward asymmetry in theB^þandB⁰decay modes, and theK⁰longitudinal polarization fraction in theB⁰ decay mode with respect to the squared dimuon mass. These are consistent with the predictions, and most recent determinations from other experiments and of comparable accuracy. We also report the first observation of theB⁰s !^þdecay and measure its branching ratioBRðB⁰_s !^þÞ ¼ ½1:44 0:330:46 10⁶using276signal events. This is currently the most rareB⁰sdecay observed.

DOI:10.1103/PhysRevLett.106.161801 PACS numbers: 13.20.He

The flavor-changing neutral current process b!s‘‘

occurs in the standard model (SM) through higher order diagrams where new physics contributions could arise.

Accurate SM predictions make theb!s‘‘phenomenol- ogy suited to uncover early indications of new physics [1–3], especially through observables like the lepton forward-backward asymmetry (AFB) and the differential branching fraction (BR) as a function of dilepton mass M‘‘. The b!s‘‘amplitudes can be described in terms

of short distance operators and effective Wilson coefficients C7;9;10. Some new physics models [1] allow the flipped sign ofC7. This results in the opposite sign ofAFBin the smallq² region (q²M²_‘‘c²). Recently,BABARand Belle [4] mea- sured anAFB in the B⁰!K⁰‘^þ‘ decay larger than the SM expectation. The decay B⁰s!ð1020Þ^þhas not been seen in previous searches by CDF [5] and D0 [6].

In this Letter we report an update of our previous analysis [5] of the rare decay modes B^þ!K^þþ,

B⁰ !K^0þ, and B⁰_s !^þ using an increased data sample offfiffiffi pp collisions at a center-of-mass energy of ps

¼1:96 TeVcorresponding to an integrated luminosity of 4:4 fb¹, collected with the CDF II detector between March 2002 and January 2009. We update the BR mea- surements and also report the measurement ofAFB in the B⁰ !K^0þdecay.

We reconstruct B!h^þ candidates, where B stands forB^þ,B⁰, orB⁰s, andhstands forK^þ,K⁰, or, respectively. Charge-conjugation is implied throughout the Letter. TheK⁰() meson is reconstructed in the decay K⁰ !K^þ (!K^þK). We also reconstruct B!J=chdecays as normalization channels in BR mea- surements, because they have final states identical to those of the signals, resulting in a cancellation of many system- atic uncertainties. The relative BR’s are

BRðB!h^þÞ

BRðB!J=chÞ ¼Nh^þ

NJ=ch

"J=ch

"_h^þ

BRðJ=c !^þÞ; (1) where N_h^þ (NJ=ch) is the B!h^þ (B!J=ch) yield, and "h^þ="J=ch is the relative reconstruction efficiency determined from the simulation.

The CDF II detector is described in detail in Ref. [7]

with the detector subsystems relevant for this analysis discussed in Ref. [8].

A sample of dimuon events is selected by the online trigger system. The trigger requires two opposite charged particles with transverse momentum pT 1:5 or 2:0 GeV=c depending on the trigger condition, matched to the muon chambers. We use the muon chambers detect muons withinjj<0:6and0:6<jj<1:0[9]. The trig- ger also requires Lxy>200m, where Lxy is the trans- verse displacement of their intersection from the beam line.

The detail of the trigger system and selection requirements can be found in Ref. [5].

The offline loose event selection begins by looking for a common vertex of two trigger muons with one (two opposite-charge) reconstructed charged particle(s) to form a B^þ!K^þþ (a B⁰ !K^0þ or a B⁰_s !^þ) candidate. The probability of the vertex fit ² is required to be greater than 10³. All charged particle trajectories are required to be associated with hits in the silicon vertex detector and to have pT 0:4 GeV=c. In addition, we require pTðhÞ 1:0 GeV=c andpTðBÞ 4:0 GeV=c. We require that theBcandidate’s decay is consistent with being displaced from the primary interaction point in the transverse plane by LxyðBÞ=

ðL_xyðBÞÞ3, andðL_xyðBÞÞis the estimated uncertainty ofL_xyðBÞ. We also require that theBcandidate comes from the primary vertex byjd0ðBÞj 120m, whered0ðBÞis the distance of closest approach of theBtrajectory to the beam line.

ForB⁰ (B⁰_s) candidates theK^þ (K^þK) mass must lie within 50 ð10ÞMeV=c² of the world average K⁰ () mass [10]. The ambiguity of the mass assignment in the K⁰!K^þ decay is handled by choosing the combina- tion with the K^þ mass closer to the knownK⁰ mass.

This results in the correct mass assignments for about 92%

of the decays as determined from the simulation. Particle identification is performed with the time of flight and the ionization energy loss (dE=dx) probabilities of the particle hypothesis. We require loose particle identification for both kaons and pions coming from theK⁰meson ormeson to reduce combinatorial background. This removes 15% of the B mass sideband events while 99.5% of the signal is retained. We also require a muon likelihood [11] to sup- press hadron tracks that produce false trigger muons.

Rare decay candidates with a dimuon mass near the J=c ⁽c^{0) are rejected: 8}:68ð12:86Þ< q²<

10:09ð14:18ÞGeV²=c². To eliminate the radiative charmo- nium decays that escaped rejection above, we remove candidates consistent with originating from a B! J=cð⁰Þh decay followed by the decay of the J=cð⁰Þ into two muons and a photon: jðMðhÞ M_B^PDGÞ ðMðÞ M_J=^PDG_cð0ÞÞj<100 MeV=c², where the PDG superscript indicates known experimental averages [10]

and MðÞ<M^PDG_J=cð0Þ. We also reject candidates if an opposite sign hadron-muon combination of the daughters, assigned the muon mass, satisfy J=c ^or c⁰ mass within 40 MeV=c². This removes charmonium decays where one of the muons is misidentified as a hadron. We reject candidates in which two (three) track combinations are compatible within 25 MeV=c² with D⁰ !K^þ (D^þ!K^þþ or D^þ_s !K^þK^þ) decays for B^þ, B⁰, and B⁰_s decays, respectively. This removes B!D (D¼D⁰, D^þ, and D^þ_s) decays where two hadrons are misidentified as muons.

We train an artificial neural network (NN) classifier on simulated signal and a sample of events representative of the background events in the signal region. To simulate the signal we use PYTHIAandEVTGEN [12] based on the SM expectation [1]. The background sample is obtained from the sidebands of theBinvariant mass distribution. We take only the higher mass sideband for the B^þ andB⁰ decays since the lower sideband is populated with physics back- ground from partially reconstructed Bmeson decays. We use both sidebands forB⁰sdecays. We use 7–10 observables based onBand daughter’s kinematics (e.g.,pT and mass), vertex qualities, and muon likelihoods. We optimize the NN threshold in order to maximize both the BR and the AFB significance. For theB^þandB⁰ analysis we optimize the NN threshold by maximizingN_s= ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi

N_sþN_b

p , whereN_s (N_b) is the expected number of signal (background) events.

We determineNsby Eq. (1) with the world average BR and NN cut efficiency of the simulated signal events, and determine Nb from the number of sideband events scaled to the signal region, which is defined as 2 from the 161801-4

world averageBmass, and NN cut efficiency of the side- band events. ForB⁰sdecays,Nsis taken from a theoretical prediction [13]. We maximizeNs=ð5=2þ ffiffiffiffiffiffi

Nb

p Þ[14].

The signal yield is obtained by an unbinned maximum log-likelihood fit to the B candidate invariant mass di- stribution. The likelihood is given by L¼Q

ðfsigPsigþ ð1fsigÞPbgÞ, wherefsigis the signal fraction,Psigis the signal probability density functions (PDF) parametrized with two Gaussian distributions with different means, andPbg is the background PDF modeled with a first- or second-order polynomial. The signal PDF’s are determined from the simulated signal and the B mass resolution is scaled by the ratio of the mass resolution inJ=chdata and simulation, which ranges from 1.07 to 1.09. The back- ground PDF’s are determined from sideband data. Fitted parameters arefsig, the meanBmass, and the background shape. The fit range for B^þ and B⁰ (B⁰s) decays is from 5.18 (5.00) to5:70 GeV=c², to avoid the region dominated by the physics background.

While the contribution from charmless B decays is negligible due to the muon identification, we find a sizeable crosstalk between B⁰ !K^0þ and B⁰s !^þ contributing approximately 1% of the sig- nal, as estimated from simulation. These contributions, whose fractions are determined by simulation assuming the world average BR and the theoretical prediction [13], are subtracted from the fit results for the signal yields.

By optimized NN threshold we reject 99.5%–99.8% of background events in the signal region. Figure1shows the Bffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffimass distributions. The statistical significance is s

2 lnðLnull=LmaxÞ

p , where Lmax is obtained from a fit with the signal fraction free to float and the meanBmeson mass fixed to the fitted value in the corresponding normal- ization channel, and Lnull is the maximum likelihood obtained from a fit with fsig¼0. Systematic uncertainty is not considered in the significance evaluation. We obtain s¼8:5, 9:7, and 6:3 for B^þ, B⁰, and B⁰s decays, respectively. The observed yields are listed in Table I.

This is the first observation of theB⁰_s !^þ mode.

We do not apply a NN selection to J=ch channels, because these signals are of sufficient size and purity with the loose selection. To obtain the relative efficiency of Eq. (1), the NN cut efficiency of the loosely selected events is considered in addition to the relative efficiency of the loose selection.

The dominant source of systematic uncertainty for each BR measurement is the background PDF parameterization (3.9%) for B^þ, the discrepancy of the NN cut efficiency between data and simulation (4.8%) for B⁰, and particle identification (3.5%) forB⁰_s. For the absolute BR measure- ments we assign the uncertainties of the world average BRðB!J=chÞ[10].

Results of the relative BR [Eq. (1)] measurements are listed in Table II. The BR statistical uncertainties include the Poisson term from finite statistics of the sample. We also show the absolute BR which is obtained by replacing the normalization channel’s BR with the corresponding world average [10] value.

These numbers are consistent with our previous results [5],B-factory measurements [4,15], and theoretical expec- tations [13]. We also measure differential BRs with respect to the dimuon mass. Events in the signal mass region are grouped into independent q² bins. Figures 2(a) and 2(b) show the differential BR for B^þ!K^þþ and B⁰!K^0þ.

The AFB and the K⁰ longitudinal polarization fraction (FL) are extracted by an unbinned likelihood fit to the cos andcosK distributions, respectively, where is the angle between the^þ() direction and the direction opposite to theB(B) meson in the dimuon restframe, and K is the angle between the kaon direction and the direc- tion opposite to the B meson in the K⁰ rest frame. The differential decay rates [2] are sensitive to cosK and cos through the angular distributions given by

32F_Lcos²_Kþ³₄ð1F_LÞð1cos²_KÞ for cos_K and

34FLð1cos²Þ þ³₈ð1FLÞð1þcos²Þ þAFBcos

for cos. We measureFL andAFB for B⁰!K^0þ

)2Events / (20 MeV/c

0 10 20 30 40 50 60

µ-

µ+

K*0

→ B0

± 12 Yield:101

3 MeV/c2

± Mass:5284

Data Total Fit Signal Background

5 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5 5.1 5.2 5.3 5.4 5.5 5.6 5.7 )2Events / (20 MeV/c

0 2 4 6 8 10 12 14 16 18 20 22

µ-

µ+

φ

→

0

Bs

± 6 Yield:27

5 MeV/c2

± Mass:5365

Data Total Fit Signal Background

FIG. 1 (color online). Mass of B⁰!K^0þ and B⁰s ! ^þ candidates with fit results overlaid. The vertical lines show the signal region.

TABLE II. Measured branching fractions of rare modes. First (second) uncertainty is statistical (systematic).

Mode RelativeBRð10³Þ AbsoluteBRð10⁶Þ B^þ!K^þþ 0:380:050:02 0:380:050:03 B⁰!K^0þ 0:800:100:06 1:060:140:09 B⁰s!^þ 1:110:250:09 1:440:330:46 TABLE I. Summary of observed yields. The numbers in parentheses are the number of events in the signal region.

Mode Nh^þ NJ=ch "h^þ="J=ch

B^þ 12116(218) 43 704245(55296) 0:4340:006 B⁰ 10112(140) 15 815178(22952) 0:4770:009 B⁰s 276(40) 293064(3883) 0:4980:012

and also AFB for B^þ !K^þþ. Angular acceptances are obtained from simulated signal samples assuming un- polarized decays.

The contribution from decays withKswappedK⁰ mesons distorts the signal distribution and swaps the sign ofcos. This effect is considered by adding an additional signal-like term to the likelihood function. The contribu- tion from decays with nonresonantKis considered to be small [2] and neglected in the fit. For theB^þdecay, we setF_L¼1and consider no scalar term [3].

The combinatorial background PDF shape is taken from theBmass upper sideband that is used for the NN training.

In the fit to cosK (cos) distribution, the only free parameter isFL (AFB). For thecos fit, the value of FL

is fixed to thecosK fit result.

Most dominant source of systematic uncertainty for each angular fit is the fit bias near the physical boundary (0.02–0.07) for FL in B⁰, the uncertainty of the FL fit (0.02–0.12) for AFB in B⁰, and the angular background shape (0.01–0.07) for AFB in B^þ. The total systematic uncertainties lie in the range 0.02–0.08 for FL in B⁰, 0.05–0.25 for AFB in B⁰, and 0.02–0.08 for AFB in B^þ. The angular fit results are shown in Fig.2(c)and2(d)and summarized in Table III. Results in the range 0q²<

4:3 GeV²=c²and1q²<6 GeV²=c²are also included.

In summary, we have updated our previous analysis of the flavor-changing neutral current decaysb!susing data corresponding to an integrated luminosity of4:4 fb¹. We report the first observation of the B⁰s !^þ, the most rareB⁰_sdecay observed to date, and measure the total BR. We measure the total BR, differential BR,AFB of the B^þ!K^þþandB⁰!K^0þ, with respect toq². We also measure F_L of B⁰!K^0þ prior to AFB. These are consistent and competitive with the other current best results. At present there is no evidence of discrepancy from the SM prediction.

We thank the Fermilab staff and the technical staffs of the participating institutions for their vital contributions. This work was supported by the U. S. Department of Energy and National Science Foundation; the Italian Istituto Nazionale di Fisica Nucleare; the Ministry of Education, Culture, Sports, Science and Technology of Japan; the Natural Sciences and Engineering Research Council of Canada;

the National Science Council of the Republic of China;

the Swiss National Science Foundation; the A.P. Sloan Foundation; the Bundesministerium fu¨r Bildung und Forschung, Germany; the World Class University Program, the National Research Foundation of Korea; the Science and Technology Facilities Council and the Royal Society, UK; the Institut National de Physique Nucleaire et Physique des Particules/CNRS; the Russian Foundation for

2)

2/c (GeV q2

)2/c2/GeV-7 (102dBR/dq

0 0.1 0.2 0.3 0.4 0.5 (a)

2)

2/c (GeV q2

0 2 4 6 8 10 12 14 16 18 20 22 0 2 4 6 8 10 12 14 16 18 )2/c2/GeV-7 (102dBR/dq

0 0.2 0.4 0.6 0.8 1

1.2 (b)

2)

2/c (GeV q2

LF

-0.2 0 0.2 0.4 0.6 0.8 1 1.2

Data SM SM

=-C7 C7

-) µ µ+ K*0

→ (B0 FL

(c)

2)

2/c (GeV q2

0 2 4 6 8 10 12 14 16 18 0 2 4 6 8 10 12 14 16 18

FBA

-0.5 0 0.5 1 1.5 2

Data SM SM

=-C7 C7

-) µ µ+ K*0

→ (B0 AFB

(d)

FIG. 2 (color online). Differential BR ofB^þ!K^þþ(a) and differential BR (b), longitudinal K⁰ polarization fraction (c), and forward-backward asymmetry (d) ofB⁰!K^0þ, as a function of squared dimuon mass. Points are the fit result.

The solid curves are the SM expectation [1]. Two solid curves in (a),(b) use maximum- and minimum- allowed form factors on differential BR plots. The dotted curves are the C7¼ C^SM₇ expectation. The dashed line is the averaged expectation in each squared dimuon mass bin and hatched regions are charmonium veto regions.

TABLE III. Summary ofB⁰!K^0þandB^þ!K^þþfit results. Maximumq² is19:30ð23:00ÞGeV²=c²forB⁰(B^þ).

q²(GeV²=c²) BRðB⁰Þ(10⁷) FLðB⁰Þ AFBðB⁰Þ BRðB^þÞ(10⁷) AFBðB^þÞ

½0:00;2:00Þ 0:980:400:09 0:53^þ0:32_0:340:07 0:13^þ1:65_0:750:25 0:380:160:03 0:15^þ0:46_0:390:08

½2:00;4:30Þ 1:000:380:09 0:40^þ0:32_0:330:08 0:19^þ0:40_0:410:14 0:580:190:04 0:72^þ0:40_0:350:07

½4:30;8:68Þ 1:690:570:15 0:82^þ0:19_0:230:07 0:06^þ0:30_0:280:05 0:930:250:06 0:20^þ0:17_0:280:03

½10:09;12:86Þ 1:970:470:17 0:31^þ0:19_0:180:02 0:66^þ0:23_0:200:07 0:720:170:05 0:10^þ0:17_0:150:07

½14:18;16:00Þ 1:510:360:13 0:55^þ0:17_0:180:02 0:42^þ0:16_0:160:09 0:380:120:03 0:03^þ0:49_0:160:04

½16:00;19:30ð23:00ÞÞ 1:350:370:12 0:09^þ0:18_0:140:03 0:70^þ0:16_0:250:10 0:350:130:02 0:07^þ0:30_0:230:02

½0:00;4:30Þ 1:980:550:18 0:47^þ0:23_0:240:03 0:21^þ0:31_0:330:05 0:960:250:06 0:36^þ0:24_0:260:06

½1:00;6:00Þ 1:600:540:14 0:50^þ0:27_0:300:03 0:43^þ0:36_0:370:06 1:010:260:07 0:08^þ0:27_0:220:07 161801-6

Basic Research; the Ministerio de Ciencia e Innovacio´n, and Programa Consolider-Ingenio 2010, Spain; the Slovak R&D Agency; and the Academy of Finland.

aDeceased.

bWith visitors from University of Massachusetts Amherst, Amherst, MA 01003, USA.

cWith visitors from Istituto Nazionale di Fisica Nucleare, Sezione di Cagliari, 09042 Monserrato (Cagliari), Italy.

dWith visitors from University of California Irvine, Irvine, CA 92697, USA.

eWith visitors from University of California Santa Barbara, Santa Barbara, CA 93106, USA.

fWith visitors from University of California Santa Cruz, Santa Cruz, CA 95064, USA.

gWith visitors from CERN,CH-1211 Geneva, Switzerland.

hWith visitors from Cornell University, Ithaca, NY 14853, USA.

iWith visitors from University of Cyprus, Nicosia CY- 1678, Cyprus.

jWith visitors from University College Dublin, Dublin 4, Ireland.

kWith visitors from University of Fukui, Fukui City, Fukui Prefecture, Japan 910-0017.

lWith visitors from Universidad Iberoamericana, Mexico D.F., Mexico.

mWith visitors from Iowa State University, Ames, IA 50011, USA.

nWith visitors from University of Iowa, Iowa City, IA 52242, USA.

oWith visitors from Kinki University, Higashi-Osaka City, Japan 577-8502.

pWith visitors from Kansas State University, Manhattan, KS 66506, USA.

qWith visitors from University of Manchester, Manchester M13 9PL, England.

rWith visitors from Queen Mary, University of London, London, E1 4NS, England.

sWith visitors from Muons, Inc., Batavia, IL 60510, USA.

tWith visitors from Nagasaki Institute of Applied Science, Nagasaki, Japan.

uWith visitors from National Research Nuclear University, Moscow, Russia.

vWith visitors from University of Notre Dame, Notre Dame, IN 46556, USA.

wWith visitors from Universidad de Oviedo, E-33007 Oviedo, Spain.

xWith visitors from Texas Tech University, Lubbock, TX 79609, USA.

yWith visitors from IFIC(CSIC-Universitat de Valencia), 56071 Valencia, Spain.

zWith visitors from Universidad Tecnica Federico Santa Maria, 110v Valparaiso, Chile.

aaWith visitors from University of Virginia, Charlottesville, VA 22906, USA.

bbWith visitors from Yarmouk University, Irbid 211-63, Jordan.

ccOn leave from J. Stefan Institute, Ljubljana, Slovenia.

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