Observation of B0s →K*∓ K∓ and evidence for B0s →K* −π+ decays

PAPER • OPEN ACCESS Observation of and evidence for decays To cite this article: The LHCb Collaboration1 et al 2014 New J. Phys. 16 123001 View the article online for updates and enhancements. Related content CP violation in the B system T Gershon and V V Gligorov - Recent charm physics results from BABAR Ryan M White - CP violation, UK Phenomenology Workshop 2000 Tobias Hurth, Choong Sun Kim, Claire Shepherd-Themistocleous et al. - Recent citations Averages of b-hadron, c-hadron, and $$\tau $$ -lepton properties as of summer 2016 Y. Amhis et al - Optical diagnostics of reactive species in atmospheric-pressure nonthermal plasma Ryo Ono - Atmospheric pressure plasma jets: an overview of devices and new directions J Winter et al - This content was downloaded from IP address 83.47.59.233 on 28/04/2020 at 08:23 Observation of B0 s→K7K∓and evidence for B0 s→K− π+decays The LHCb Collaboration 1 Received 31 July 2014, revised 24 September 2014 Accepted for publication 10 October 2014 Published 2 December 2014 New Journal of Physics 16 (2014) 123001 doi:10.1088/1367-2630/16/12/123001 Abstract Measurements of the branching fractions of →±∓ BKK * s 0and π→± ∓ BK * s 0 decays are performed using a data sample corresponding to − 1.0 fb 1 of protonproton collision data collected with the LHCb detector at a centre-of-mass energy of 7 Te V , where the ± K * mesons are reconstructed in the π ± K S 0final state. The first observation of the →±∓ BKK * s 0decay and the first evidence for the π→− + BK * s 0decay are reported with branching fractions  π →=±±× →=±±× ±∓ − −+− () () BKK BK *(12.7 1.9 1.9) 10 , *(3.3 1.1 0.5) 10 , s s 06 06 where the first uncertainties are statistical and the second are systematic. In addition, an upper limit of  →<× ±∓ − () BKK *0.4 (0.5) 10 06 is set at 9 0% (95%) confidence level. Keywords: flavour physics, B physics, branching fraction 1. Introduction The Standard Model (SM) of particle physics predicts that all manifestations of CP violation, i.e. violation of symmetry under the combined charge conjugation and parity operation, arise due to the single complex phase that appears in the Cabibbo–Kobayashi–Maskawa (CKM) quark mixing matrix [1,2]. Since this source is not sufficient to account for the level of the 1 Authors are listed at the end of the paper. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Article funded by SCOAP 3 . New Journal of Physics 16 (2014) 123001 1367-2630/14/123001+18$33.00 © 2014 CERN baryon asymmetry of the Universe [3], one of the key goals of contemporary particle physics is to search for signatures of CP violation that are not consistent with the CKM paradigm. Among the most important areas being explored in quark flavour physics is the study of B meson decays to hadronic final states that do not contain charm quarks or antiquarks (hereafter referred to as ‘charmless’). As shown in figure 1, such decays have, in general, amplitudes that contain contributions from both ‘tree’and ‘loop’diagrams (see, e.g., [4]). The phase differences between the two amplitudes can lead to CP violation and, since particles hypothesized in extensions to the SM may affect the loop diagrams, deviations from the SM predictions may occur. Large CP violation effects, i.e. asymmetries of  (10%) or more between the rates of B ¯ and Bmeson decays to CP conjugate final states, have been seen in π→+− BK 0[5–8], π→− + BK s 0[7,8], and ππ→ ++−+ BK , +−+ K KK ,πππ +−+ and π +− + K K decays [9–11]. However, it is hard to be certain whether these measurements are consistent with the SM predictions due to the presence of parameters describing the hadronic interactions that are difficult to determine either theoretically or from data. An interesting approach to control the hadronic uncertainties is to exploit amplitude analysis techniques. For example, by studying the distribution of kinematic configurations of ππ→+− BK S 00decays across the Dalitz plot [12], the relative phase between the π +− K * and ρ K S 00amplitudes can be determined. This information is not accessible in studies either of twobody decays, or of the inclusive properties of three-body decays. Consequently, it may be possible to make more sensitive tests of the SM by studying decays to final states having contributions from intermediate states with one vector and one pseudoscalar meson (VP), rather than in those with two pseudoscalars. Several methods to test the SM with BmesondecaystocharmlessVP( π K * and ρ K ) states have been proposed [13–18]. The experimental inputs needed for these methods are the magnitudes and relative phases of the decay amplitudes. Although the phases can only be obtained from Dalitz plot analyses of Bmeson decays to final states containing one kaon and two pions, the magnitudes can be obtained from simplified approaches. Dalitz plot analyses have been performed for the decays ππ→ +++− BK [19,20], ππ→+− BK S 00[21,22]and ππ→+− BK 00 [23]. Decays of Bmesons to K K * final states can in principle be studied with similar methods, but the existing experimental results are less precise [24–29]. No previous measurements of B s 0 meson decays to charmless VP final states exist. First results from the LHCb collaboration on inclusive three-body charmless B s 0 decays have recently become available [30], but no attempt has previously been made to separate the different resonant and nonresonant contributions to their Dalitz plots. In this paper, the first measurements of B s 0 meson decays to π − + K * and ±∓ K K * final states and of the → ± ∓ BKK * 0 rate are reported. Throughout the remainder of the paper the symbol K *is used to denote the K *(892 ) resonance. Unique charge assignments of the final state Figure 1. (a) Tree and (b) loop diagrams for the decay →+− B KK * s 0. 2 New J. Phys. 16 (2014) 123001 R Aaij et al particles are specified in the expression π→− + BK * s 0because the amplitude for π→+− BK * s 0 is expected to be negligibly small; however, the inclusion of charge-conjugate processes is implied throughout the paper. The branching fractions are measured relative to that of the π→+− BK * 0decay, which is known from previous measurements, π→ =±× +− − () BK *(8.5 0.7) 10 06 [31]. Each of the relative branching fractions for →±∓ BKh * s 0, where hrefers either to a pion or kaon, are determined as  π ϵπ ϵπ → → = → → → → ±∓ +− +− ±∓ ±∓ +− () () () () () () BKh BK f f BK BKh NB K h NB K ,(1) * * * * * * sd ss s 0 0 0 0 0 0 while that for → ± ∓ BKK * 0 is determined as  π ϵπ ϵπ → → = → → → → ±∓ +− +− ±∓ ±∓ +− () () () () () () BKK BK BK BKK NB K K NB K ,(2) * * * * * * 0 0 0 0 0 0 where Nare signal yields obtained from data, ϵare efficiencies obtained from simulation and corrected for known discrepancies between data and simulation, and the ratio of fragmentation fractions =±ff 0.259 0.01 5 sd [32–34]. With this approach, several potentially large systematic uncertainties cancel in the ratios. The ± K * mesons are reconstructed in their decays to π ± K S 0with ππ→+ − K S 0and therefore the final states π ±∓ K h S 0 , as well as the data sample, are identical to those studied in [30]. Although the analysis shares several common features to that of the previous publication [30], the selection is optimized independently based on the expected level of background within the allowed π ± K S 0mass window. The data sample used is too small for a detailed Dalitz plot analysis, and therefore only branching fractions are measured. The fit used to distinguish signal from background is an unbinned maximum likelihood fit in the two dimensions of Bcandidate and K * candidate invariant masses. This approach allows the resonant →± ∓ BKh *decaytobe separated from other Bmeson decays to the π ±∓ K h S 0 final state. It does not, however, account for interference effects between the ±∓ K h * component and other amplitudes contributing to the Dalitz plot; possible biases due to interference are considered as a source of systematic uncertainty. 2. The LHCb detector The analysis is based on a data sample corresponding to an integrated luminosity of − 1.0fb 1 of pp collisions at a centre-of-mass energy of 7 Te V recorded with the LHCb detector at CERN. The LHCb detector [35] is a single-arm forward spectrometer covering the pseudorapidity range η<< 2 5 , designed for the study of particles containing bor cquarks. The detector includes a high-precision tracking system consisting of a silicon-strip vertex detector (VELO) [36] surrounding the pp interaction region, a large-area silicon-strip detector located upstream of a dipole magnet with a bending power of about 4 Tm, and three stations of silicon-strip detectors and straw drift tubes [37] placed downstream. The tracking system provides a momentum measurement with relative uncertainty that varies from 0.4% at low momentum to 0.6% at 100 GeV/c. The minimum distance of a track to a primary vertex, the impact parameter, is measured with resolution of μ 2 0m for tracks with large momentum transverse to the beamline ( p T ). Different types of charged hadrons are distinguished using information from two ringimaging Cherenkov detectors [38]. Photon, electron and hadron candidates are identified by a 3 New J. Phys. 16 (2014) 123001 R Aaij et al calorimeter system consisting of scintillating-pad and preshower detectors, an electromagnetic calorimeter and a hadronic calorimeter. Muons are identified by a system composed of alternating layers of iron and multiwire proportional chambers [39]. The trigger [40] consists of hardware and software stages. The hadron trigger at the hardware stage requires that there is at least one particle with transverse energy > E 3.5Ge V T. Events containing candidate signal decays are required to have been triggered at the hardware level in one of two ways. Events in the first category are triggered by particles from candidate signal decays that have an associated calorimeter energy deposit above the threshold, while those in the second category are triggered independently of the particles associated with the signal decay. Events that do not fall into either of these categories are not used in the subsequent analysis. The software trigger requires a two-, three- or four-track secondary vertex with a large sum of the p T of the tracks and a significant displacement from the primary pp interaction vertices (PVs). A multivariate algorithm [41] is used for the identification of secondary vertices consistent with the decay of a bhadron. Simulated events are used to study the detector response to signal decays and to investigate potential sources of background. In the simulation, pp collisions are generated using PYTHIA [42] with a specific LHCb configuration [43]. Decays of hadronic particles are described by EVTGEN [44], in which final state radiation is generated using PHOTOS [45]. The interaction of the generated particles with the detector and its response are implemented using the GEANT4 toolkit [46] as described in [47]. 3. Selection requirements The trigger and preselection requirements are identical to those in [30]. As in that analysis, and those of other final states containing K S 0 mesons [48–52], candidate signal decays, i.e. combinations of tracks that are consistent with the signal hypothesis, are separated into two categories: ‘long’, where both tracks from the ππ→+ − K S 0decay contain hits in the VELO, and ‘downstream’, where neither does. Both categories have associated hits in the tracking detectors downstream of the magnet. Since long candidates have better mass, momentum and vertex resolution, different selection requirements are imposed for the two categories. The two tracks originating from the Bdecay vertex, referred to hereafter as ‘bachelor’ tracks, are required not to have associated hits in the muon system. Backgrounds from decays with charm or charmonia in the intermediate state are vetoed by removing candidates with twobody invariant mass under the appropriate final state hypothesis within 3 0MeV/c of the known masses [53]. Vetoes are applied for ψππ→+− J or +− K K ,χππ→+− c0or +− K K ,π→−+ DK 0, ππ +− or +− K K , π→ + + DK S 0 or + K K S 0, π→ + + DK sS 0 or + K K S 0and Λ→ + Kp cS 0 decays. The largest source of potential background is from random combinations of final state particles, hereafter referred to as combinatorial background. Signal candidates are separated from this source of background with the output of a neural network [54] that is trained and optimized separately for long and downstream candidates. In the training, simulated →±∓ BKK * s 0decays are used to represent signal, and data from the high mass sideband of ππ + − K S 0candidates are used as a background sample (the sideband is ππ<−< +− mK m 4 0 ( ) 150 MeV/c SB 00,where m B 0is the known value of the B 0 mass [53]). The variables used are: the values of the impact parameter χ 2 ,defined as the difference in χ 2 of the associated PV with and without the considered particle, for the bachelor tracks and the K S 0 and Bcandidates; the vertex fitχ 2 for the 4 New J. Phys. 16 (2014) 123001 R Aaij et al K S 0 and Bcandidates; the angle between the Bcandidate flight direction and the line between the associated PV and the decay vertex; the separation between the PV and the decay vertex divided by its uncertainty; and the Bcandidate p T . Some of these variables are transformed into their logarithms or other forms that are more appropriate for numerical handling. The consistency of the distributions of these variables between data and simulation is confirmed for ππ→+− BK S 00 decays using the sPlot technique [55]withtheBcandidate mass as discriminating variable. The criteria on the outputs of the neural network are chosen to optimize the probability to observe the →±∓ BKK * s 0decay with significance exceeding five standard deviations (σ)[56]. For the optimization, an additional requirement on the π ± K S 0invariant mass, π−< ±± mK m( ) 100 MeV/c SK 0*with ± mK*the known ± K * mass, calculated with the Band K S 0 candidates constrained to their known masses, is imposed to select the ± K * dominated region of the phase space. The requirements on the neural network output give signal efficiencies exceeding 90% for candidates containing long K S 0 candidates and exceeding 80% for candidates containing downstream K S 0 candidates, while approximately 95% and 92% of the background is removed from the two categories, respectively. Requirements are imposed on particle identification information, primarily from the ringimaging Cherenkov detectors [38], to separate ±∓ K K * and π ± ∓ K * decays. The criteria are chosen based on optimization of a similar figure of merit to that used to obtain the requirement on the neural network output, and retain about 70% of ±∓ K K * and about 75% of π ± ∓ K * decays. Candidates with tracks that are likely to be protons are rejected. After all selection requirements are applied, below 1% of events containing one candidate also contain a second candidate; all such candidates are retained. 4. Determination of signal yields Candidates with masses inside the fit windows of π<< ±∓ mK h 5 000 ( ) 5500 MeV/c S 0and π<< ± mK650 ( ) 1200 MeV/c S 0are used to perform extended unbinned maximum likelihood fits to determine the signal yields. In these fits, signal decays are separated from several categories of background by exploiting their distributions in both π ±∓ mK h() S 0 and π± mK( ) S 0. The mass of the π ±∓ K h S 0 combination is calculated assigning either the kaon or pion mass to ∓ h according to the outcome of the particle identification requirement. A single simultaneous fitto both long and downstream candidates is performed. Separate fits are performed for ±∓ K K * and π ± ∓ K * candidates. In addition to the signal components and combinatorial background, candidates can originate from several other bhadron decays. Potential sources include: decays of B0and B s 0 mesons to π ±∓ K h S 0 final states without an intermediate K *state (referred to as ‘nonresonant’); misidentified → ±∓ BKh * s() 0(referred to as ‘cross-feed’)andΛ→− Kp * b 0decays; decays of B mesons to charmless final states with an additional unreconstructed pion; and → + + BDh ¯ 0, ππ→+− DK ¯S 00decays where the additional pion is not reconstructed. Where branching fraction measurements exist [31,50,53], the yields of the background sources, except that for nonresonant ππ→+− BK S 00decays, are expected to be less than 10% of those for →±∓ BKK *. s 0 The branching fractions of the other nonresonant decays have not been previously determined. The fit includes components for both B0and B s 0 signal and nonresonant components, and the sources of background listed above. The signal components are parametrized by a Crystal 5 New J. Phys. 16 (2014) 123001 R Aaij et al Ball (CB) function [57]inBcandidate mass and a relativistic Breit–Wigner (RBW) function in K *candidate mass. The peak positions and widths of the functions for the dominant contribution ( B s 0 for ±∓ K K * ,B0for π ± ∓ K * ) are allowed to vary freely in the fit. The relative positions of the B0and B s 0 peaks in the Bcandidate mass distribution are fixed according to the known B0– B s 0 mass difference [53]. The tail parameters of the CB function are fixedtothevaluesfoundinfits to simulated signal events, as are the relative widths of the B0and B s 0 shapes. Cross-feed contributions are also described by the product of CB and RBW functions with parameters determined from simulation. The misidentification causes a shift and a smearing of the B candidate mass distribution and only small changes to the shape in the K *candidate mass. The Bcandidate mass distributions for the nonresonant components are also parametrized by a CB function, with peak positions and widths identical to those of the signal components, but with different tail parameters that are fixed to values obtained from simulation. Within the K *mass window considered in the fit, the nonresonant shape can be approximated with a linear function. All linear functions used in the fit are parametrized by their yield and the abscissa value at which they cross zero, and are set to zero beyond this threshold, m 0 . The relative yields of nonresonant and signal components are constrained to have the same value in the samples with long and downstream candidates, but this ratio is allowed to be different for B0and B s 0 decays. Backgrounds from other bhadron decays are described nonparametrically by kernel functions [58] in the Bcandidate mass and either RBW or linear functions in the K *candidate mass, depending on whether or not the decay involves a K *resonance. All these background shapes are determined from simulation. To reduce the number of free parameters in the fit to the ±∓ K K * sample, the yields of the backgrounds from charmless hadronic Bmeson decays with missing particles are fixed relative to the yield for the π→+− BK * 0cross-feed component according to expectation. The yield of the → + + BDh ¯ 0,ππ→+− DK ¯S 00component is determined from the fit to data. The yield for the Λ→− Kp * b 0contribution is also a free parameter in the fitto ±∓ K K * candidates, but is fixed to zero in the fitto π ± ∓ K * candidates. The combinatorial background is modelled with linear functions in both Band K * candidate mass distributions, with parameters freely varied in the fit to data except for the m 0 threshold in Bcandidate mass, which is fixed from fits to sideband data. For all components, the factorization of the two-dimensional probability density functions into the product of onedimensional functions is verified to be a good approximation using simulation and sideband data. In total there are 20 free parameters in the fit to the ±∓ K K * sample: yields for B0and B s 0 signals, cross-feed, Λ, b 0 →BDh and combinatorial backgrounds (all for both long and downstream categories); ratios of yields for the B0and B s 0 nonresonant components; peak position and width parameters for the signal in both Bcandidate and K *candidate mass distributions; and parameters of the linear functions describing the combinatorial background in K *candidate mass for both long and downstream categories. The fit to the π ± ∓ K * sample has the same number of free parameters, with the Λ b 0 background yields replaced by charmless background yields. The stability of both fits is confirmed using simulated pseudoexperiments. The results of the fits are shown in figures 2and 3for the ±∓ K K * and π ± ∓ K * final states, respectively, and the signal yields are given in table 1. All other fit results are consistent with expectations. 6 New J. Phys. 16 (2014) 123001 R Aaij et al 5. Systematic uncertainties Systematic uncertainties occur due to possible imperfections in the fit model used to determine the signal yields, and due to imperfect knowledge of the efficiencies used to convert the yields to branching fraction results. A summary of the systematic uncertainties is given in table 2. The fixed parameters in the functions describing the signal and background components are varied within their uncertainties, and the changes in the fitted yields are assigned as systematic uncertainties. Studies with simulated pseudoexperiments cannot exclude biases on Figure 2. Results of the fitto ±∓ KK *candidates projected onto (a), (b) Bcandidate and (c), (d) K* candidate mass distributions, for (a), (c) long and (b), (d) downstream candidates. The total fit result (solid black line) is shown together with the data points. Components for the B 0(pink dash double-dotted line) and B s 0 (red dash dotted line) signals are shown together with the B s 0 nonresonant component (dark red falling-hatched area), charmless partially reconstructed and cross-feed background (blue long-dashed line), and combinatorial background (green long-dash dotted line) components. The → ++ B Dh ¯ 0 background component has a negative yield (consistent with zero) and so is not directly visible but causes the total PDF to go below the level of the combinatorial background on the left of the Bcandidate mass spectrum. 7 New J. Phys. 16 (2014) 123001 R Aaij et al Figure 3. Results of the fitto π ±∓ K* candidates projected onto (a), (b) Bcandidate and (c), (d) K* candidate mass distributions, for (a), (c) long and (b), (d) downstream candidates. The total fit result (black solid line) is shown together with the data points. Components for the B 0(red dash dotted line) and B s 0 (pink dash double-dotted line) signals are shown together with B 0(dark red falling-hatched area) and B s 0 (purple rising-hatched area) nonresonant components, partially reconstructed and cross-feed background (blue long-dashed line), and combinatorial background (green long-dash- dotted line) components. Table 1. Yields and relative yields obtained from the fits to ±∓ KK *and π ±∓ K* candidates. The relative yields of nonresonant (NR) B s() 0 decays are constrained to be identical in long and downstream categories. Only statistical uncertainties are given. Yield B 0 B s 0 Long Downstream Long Downstream ±∓ N KK(* ) 0±4 4±3 40±8 62±10 π ±∓ N K(* ) 80±10 165±16 5±4 23±8 π±∓ ±∓ N KK NKK(NR)( * ) S 00.0 ± 1.0 0.41 ± 0.16 ππ π ±∓ ±∓ N KNK(NR)( * ) S 00.79 ± 0.14 0.6 ± 0.4 8 New J. Phys. 16 (2014) 123001 R Aaij et al 13 School of Physics, University College Dublin, Dublin, Ireland 14 Sezione INFN di Bari, Bari, Italy 15 Sezione INFN di Bologna, Bologna, Italy 16 Sezione INFN di Cagliari, Cagliari, Italy 17 Sezione INFN di Ferrara, Ferrara, Italy 18 Sezione INFN di Firenze, Firenze, Italy 19 Laboratori Nazionali dell’INFN di Frascati, Frascati, Italy 20 Sezione INFN di Genova, Genova, Italy 21 Sezione INFN di Milano Bicocca, Milano, Italy 22 Sezione INFN di Milano, Milano, Italy 23 Sezione INFN di Padova, Padova, Italy 24 Sezione INFN di Pisa, Pisa, Italy 25 Sezione INFN di Roma Tor Vergata, Roma, Italy 26 Sezione INFN di Roma La Sapienza, Roma, Italy 27 Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences, Kraków, Poland 28 AGH-University of Science and Technology, Faculty of Physics and Applied Computer Science, Kraków, Poland 29 National Center for Nuclear Research (NCBJ), Warsaw, Poland 30 Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest-Magurele, Romania 31 Petersburg Nuclear Physics Institute (PNPI), Gatchina, Russia 32 Institute of Theoretical and Experimental Physics (ITEP), Moscow, Russia 33 Institute of Nuclear Physics, Moscow State University (SINP MSU), Moscow, Russia 34 Institute for Nuclear Research of the Russian Academy of Sciences (INR RAN), Moscow, Russia 35 Budker Institute of Nuclear Physics (SB RAS) and Novosibirsk State University, Novosibirsk, Russia 36 Institute for High Energy Physics (IHEP), Protvino, Russia 37 Universitat de Barcelona, Barcelona, Spain 38 Universidad de Santiago de Compostela, Santiago de Compostela, Spain 39 European Organization for Nuclear Research (CERN), Geneva, Switzerland 40 Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland 41 Physik-Institut, Universität Zürich, Zürich, Switzerland 42 Nikhef National Institute for Subatomic Physics, Amsterdam, The Netherlands 43 Nikhef National Institute for Subatomic Physics and VU University Amsterdam, Amsterdam, The Netherlands 44 NSC Kharkiv Institute of Physics and Technology (NSC KIPT), Kharkiv, Ukraine 45 Institute for Nuclear Research of the National Academy of Sciences (KINR), Kyiv, Ukraine 46 University of Birmingham, Birmingham, UK 47 H. H. Wills Physics Laboratory, University of Bristol, Bristol, UK 48 Cavendish Laboratory, University of Cambridge, Cambridge, UK 49 Department of Physics, University of Warwick, Coventry, UK 50 STFC Rutherford Appleton Laboratory, Didcot, UK 51 School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK 52 School of Physics and Astronomy, University of Glasgow, Glasgow, UK 53 Oliver Lodge Laboratory, University of Liverpool, Liverpool, UK 54 Imperial College London, London, UK 55 School of Physics and Astronomy, University of Manchester, Manchester, UK 56 Department of Physics, University of Oxford, Oxford, UK 57 Massachusetts Institute of Technology, Cambridge, MA, USA 58 University of Cincinnati, Cincinnati, OH, USA 59 University of Maryland, College Park, MD, USA 60 Syracuse University, Syracuse, NY, USA 61 Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), Rio de Janeiro, Brazil, associated to 3 62 Institute of Particle Physics, Central China Normal University, Wuhan, Hubei, China, associated to 4 63 Institut für Physik, Universität Rostock, Rostock, Germany, associated to 12 64 National Research Centre Kurchatov Institute, Moscow, Russia, associated to 32 65 Instituto de Fisica Corpuscular (IFIC), Universitat de Valencia-CSIC, Valencia, Spain, associated to 37 66 KVI-University of Groningen, Groningen, The Netherlands, associated to 42 67 Celal Bayar University, Manisa, Turkey, associated to 39 68 Universidade Federal do Triângulo Mineiro (UFTM), Uberaba-MG, Brazil 69 P N Lebedev Physical Institute, Russian Academy of Science (LPI RAS), Moscow, Russia 15 New J. Phys. 16 (2014) 123001 R Aaij et al 70 Università di Bari, Bari, Italy 71 Università di Bologna, Bologna, Italy 72 Università di Cagliari, Cagliari, Italy 73 Università di Ferrara, Ferrara, Italy 74 Università di Firenze, Firenze, Italy 75 Università di Urbino, Urbino, Italy 76 Università di Modena e Reggio Emilia, Modena, Italy 77 Università di Genova, Genova, Italy 78 Università di Milano Bicocca, Milano, Italy 79 Università di Roma Tor Vergata, Roma, Italy 80 Università di Roma La Sapienza, Roma, Italy 81 Università della Basilicata, Potenza, Italy 82 AGH-University of Science and Technology, Faculty of Computer Science, Electronics and Telecommunications, Kraków, Poland 83 LIFAELS, La Salle, Universitat Ramon Llull, Barcelona, Spain 84 Hanoi University of Science, Hanoi, Viet Nam 85 Università di Padova, Padova, Italy 86 Università di Pisa, Pisa, Italy 87 Scuola Normale Superiore, Pisa, Italy 88 Università degli Studi di Milano, Milano, Italy 89 Politecnico di Milano, Milano, Italy References [1] Cabibbo N 1963 Unitary symmetry and leptonic decays Phys. Rev. Lett. 10 531 [2] Kobayashi M and Maskawa T 1973 CP violation in the renormalizable theory of weak interaction Prog. Theor. Phys. 49 652 [3] Riotto A and Trodden M 1999 Recent progress in baryogenesis Ann. Rev. Nucl. Part. Sci. 49 35 [4] Antonelli M et al 2010 Flavor physics in the quark sector Phys. Rep. 494 197 [5] Lees J P et al (BaBar collaboration) 2013 Measurement of CP asymmetries and branching fractions in charmless two-body B-meson decays to pions and kaons Phys. Rev. D87 052009 [6] Duh Y-T et al (Belle collaboration) 2013 Measurements of branching fractions and direct CP asymmetries for π→ B K,ππ→ B and → B KK decays Phys. Rev. D87 031103 [7] Aaij R et al (LHCb collaboration) 2013 First observation of CP violation in the decays of B s 0 mesons Phys. Rev. Lett. 110 221601 [8] Aaltonen T A et al (CDF collaboration) 2014 Measurements of direct CP-violating asymmetries in charmless decays of bottom baryons to appear in Phys. Rev. Lett. (arXiv:1403.5586) [9] Aaij R et al (LHCb collaboration) 2013 Measurement of CP violation in the phase space of ππ→ ±±+− B K and → ±±+− B KKK decays Phys. Rev. Lett. 111 101801 [10] Aaij R et al (LHCb collaboration) 2014 Measurement of CP violation in the phase space of π→ ±+−± B KK and πππ→ ± +−± B decays Phys. Rev. Lett. 112 011801 [11] Aaij R et al (LHCb collaboration) 2014 Measurement of CP violation in the three-body phase space of charmless ± B decays to appear in Phys. Rev. D (arXiv:1408.5373) [12] Dalitz R H 1953 On the analysis of tau-meson data and the nature of the tau-meson Phil. Mag. 44 1068 [13] Ciuchini M, Pierini M and Silvestrini L 2006 New bounds on the Cabibbo–Kobayashi–Maskawa matrix from ππ→ B K Dalitz plot analyses Phys. Rev. D74 051301 [14] Ciuchini M, Pierini M and Silvestrini L 2007 Hunting the CKM weak phase with time-integrated Dalitz analyses of ππ→ B K s 0decays Phys. Lett. B645 201 [15] Gronau M, Pirjol D, Soni A and Zupan J 2007 Improved method for CKM constraints in charmless threebody Band B s 0decays Phys. Rev. D75 014002 [16] Gronau M, Pirjol D, Soni A and Zupan J 2008 Constraint on ρ η ¯,¯ from π→ B K* Phys. Rev. D77 057504 16 New J. Phys. 16 (2014) 123001 R Aaij et al [17] Bediaga I, Guerrer G and de Miranda J M 2007 Extracting the quark mixing phase γfrom ππ→ ±±+− B K, ππ→ +− B K S 00 , and ππ→ +− B K ¯ S 00 Phys. Rev. D76 073011 [18] Gronau M, Pirjol D and Zupan J 2010 CP asymmetries in ππρ→ B KK K,*,decays Phys. Rev. D81 094011 [19] Garmash A et al (Belle collaboration) 2006 Evidence for large direct CP violation in ρ→ ±± B K(770) 0 from analysis of the three-body charmless ππ→ ±±±∓ B K decays Phys. Rev. Lett. 96 251803 [20] Aubert B et al (BaBar collaboration) 2008 Evidence for direct CP violation from Dalitz-plot analysis of ππ→ ±±∓± B K Phys. Rev. D78 012004 [21] Dalseno J et al (Belle collaboration) 2009 Time-dependent Dalitz plot measurement of CP parameters in ππ→ +− B K S 00 decays Phys. Rev. D79 072004 [22] Aubert B et al (BaBar collaboration) 2009 Time-dependent amplitude analysis of ππ→ +− B K S 00 Phys. Rev. D80 112001 [23] Lees J P et al (BaBar collaboration) 2011 Amplitude analysis of ππ→+− B K 00 and evidence of direct CP violation in π→ B K* decays Phys. Rev. D83 112010 [24] Aubert B et al (BaBar collaboration) 2006 Search for the decay of a B 0or B ¯0meson to KK ¯* 00 or KK *¯ 00 Phys. Rev. D74 072008 [25] Aubert B et al (BaBar collaboration) 2007 Search for the decay → ++ B KK ¯*(892)0 Phys. Rev. D76 071103 [26] Aubert B et al (BaBar collaboration) 2007 Observation of the decay π→ ++−+ B KK Phys. Rev. Lett. 99 221801 [27] Aubert B et al (BaBar collaboration) 2009 Search for the decay π→ ++ B KK SS 00 Phys. Rev. D79 051101 [28] del Amo Sanchez P et al (BaBar collaboration) 2010 Observation of the rare decay π→ ±∓ B KK S 00 Phys. Rev. D82 031101 [29] Gaur V et al (Belle collaboration) 2013 Evidence for the decay π→ +− B KK 00 Phys. Rev. D87 091101 [30] Aaij R et al (LHCb collaboration) 2013 Study of → +′− B Khh sS() 00 decays with first observation of π→ ±∓ B KK sS 00 and ππ→ +− B K sS 00 J. High Energy Phys. JHEP10(2013)143 [31] Amhis Y et al (Heavy Flavor Averaging Group) 2012 Averages of b-hadron, c-hadron, and τ-lepton properties as of early 2012 (arXiv:1207.1158), updated results and plots available at http://slac.stanford. edu/xorg/hfag/ [32] Aaij R et al (LHCb collaboration) 2012 Measurement of bhadron production fractions in 7 TeV pp collisions Phys. Rev. D85 032008 [33] Aaij R et al (LHCb collaboration) 2013 Measurement of the fragmentation fraction ratio ff s d and its dependence on Bmeson kinematics J. High Energy Phys. JHEP04(2013)001 [34] LHCb collaboration, Updated average f s /f d b-hadron production fraction ratio for 7 TeV pp collisions LHCb- CONF-2013–011 https://cds.cern.ch/record/1559262 [35] Alves A A Jr. et al (LHCb collaboration) 2008 The LHCb detector at the LHC JINST 3S08005 [36] Aaij R et al 2014 Performance of the LHCb Vertex Locator JINST 9P09007 [37] Arink R et al 2014 Performance of the LHCb Outer Tracker JINST 9P01002 [38] AdinolfiMet al 2013 Performance of the LHCb RICH detector at the LHC Eur. Phys. J. C732431 [39] Alves A A Jr. et al 2013 Performance of the LHCb muon system JINST 8P02022 [40] Aaij R et al 2013 The LHCb trigger and its performance JINST 8P04022 [41] Gligorov V V and Williams M 2013 Efficient, reliable and fast high-level triggering using a bonsai boosted decision tree JINST 8P02013 [42] Sjöstrand T, Mrenna S and Skands P 2006 PYTHIA 6.4 physics and manual J. High Energy Phys. JHEP05 (2006)026 [43] Belyaev I et al 2010 Handling of the generation of primary events in GAUSS, the LHCb simulation framework Nuclear Science Symposium Conference Record (NSS/MIC) IEEE p1155 [44] Lange D J 2001 The EvtGen particle decay simulation package Nucl. Instrum. Meth. A462 152 [45] Golonka P and Was Z 2006 PHOTOS Monte–Carlo: a precision tool for QED corrections in Z and W decays Eur. Phys. J. C45 97 17 New J. Phys. 16 (2014) 123001 R Aaij et al [46] Allison J et al (Geant4 collaboration) 2006 Geant4 developments and applications IEEE Trans. Nucl. Sci. 53 270 Agostinelli S et al (Geant4 collaboration) 2003 Geant4: a simulation toolkit Nucl. Instrum. Meth. A506 250 [47] Clemencic M et al 2011 The LHCb simulation application, GAUSS: design, evolution and experience J. Phys. Conf. Ser. 331 032023 [48] Aaij R et al (LHCb collaboration) 2013 Measurement of the time-dependent CP asymmetry in ψ→ B JK S 00 decays Phys. Lett. B721 24 [49] Aaij R et al (LHCb collaboration) 2013 Measurement of the effective ψ→ B JK sS 00 lifetime Nucl. Phys. B 873 275 [50] Aaij R et al (LHCb collaboration) 2014 Searches for Λb 0 and Ξ 0 b decays to π− Kp S 0and − KpK S 0final states with first observation of the Λπ→ − Kp bS 00 decay J. High Energy Phys. JHEP04(2014)087 [51] Aaij R et al (LHCb collaboration) 2014 Differential branching fractions and isospin asymmetries of μμ→ +− B K* () decays J. High Energy Phys. JHEP06(2014)133 [52] Aaij R et al (LHCb collaboration) 2014 Observation of the ψπ→ ±∓ B JKK sS 00 decay J. High Energy Phys. JHEP07(2014)140 [53] Beringer J et al (Particle Data Group) 2012 Review of particle physics Phys. Rev. D86 010001 and 2013 partial update for the 2014 edition [54] Feindt M and Kerzel U 2006 The NeuroBayes neural network package Nucl. Instrum. Meth. A559 190 [55] Pivk M and le Diberder F R 2005 sPlot: a statistical tool to unfold data distributions Nucl. Instrum. Meth. A 555 356 [56] Punzi G 2003 Sensitivity of searches for new signals and its optimization Statistical Problems in Particle Physics Astrophysics, and Cosmology ed L Lyons, R Mount and R Reitmeyer 79 (arXiv:physics/0308063) [57] Skwarnicki T 1986 A study of the radiative cascade transitions between the Upsilon-prime and Upsilon resonances PhD Thesis Institute of Nuclear Physics, Krakow DESY-F31–86-02 http://inspirehep.net/ record/230779/files/F37-86.02.pdf [58] Cranmer K S 2001 Kernel estimation in high-energy physics Comput. Phys. Commun. 136 198 [59] Aaij R et al (LHCb collaboration) 2014 Measurement of the charge asymmetry in ϕ→ ±± B K and search for ϕπ→ ±± B decays Phys. Lett. B728 85 [60] Cheng H-Y and Chua C-K 2009 QCD factorization for charmless hadronic B s 0decays revisited Phys. Rev. D 80 114026 [61] Ali A et al 2007 Charmless non-leptonic B s 0decays to PP, PV and VV final states in the pQCD approach Phys. Rev. D76 074018 [62] Su F, Wu Y-L, Zhuang C and Yang Y-B 2012 Charmless → B PP PV V V ,, s 0decays based on the six-quark effective Hamiltonian with strong phase effects II Eur. Phys. J. C72 1914 18 New J. Phys. 16 (2014) 123001 R Aaij et al