Charmless three body B decays      

 

B mesons decays to three-body charmless final states offer a good environment to study CP violation phenomena. They also provide important insight into the dynamics of hadronic B decays.

The LHCb Bu→hhh Rio Group has been studying charmless three-body B decays since the beginning of LHCb data taking in 2009. The first analysis was a measurement of the relative branching fractions of B^±→K^±K^±K^- and B^±→ppK^± decays with respect to the reference mode B^±→K^±π^±π^-. The analysis was performed using 34 pb^-1 of 2010 data, and was reported in the public note LHCb-CONF-2011-059. The branching ratios relative to B^±→K^±π^±π^- are found to be

• ^{ℬℛ(B±→K±K±K-)}⁄_{ℬℛ(B^±→K^±π^±π^-)} = 0.52 ± 0.003(stat) ± 0.01(syst)
• ^{ℬℛ(B±→ppK±)}⁄_{ℬℛ(B^±→K^±π^±π^-)} = 0.19 ± 0.02(stat) ± 0.02(syst)

With the bigger dataset of 3 fb^-1 of 2011 and 2012 LHCb data, we measured the direct CP asymmetries of four charmless decay modes. We found for the the first evidences of CP violation in these modes, as well as localised asymmetries much larger than the integrated ones in some regions of phase space. The results are listed below in the LHCb Collaboration Results. The inclusive CP asymmetries (A_CP) of these modes are measured to be

• A_CP(B^±→K^±π^±π^-) = +0.025 ± 0.004 ± 0.004 ± 0.007
• A_CP(B^±→K^±K^±K^-) = -0.036 ± 0.004 ± 0.002 ± 0.007
• A_CP(B^±→π^±π^±π^-) = +0.058 ± 0.008 ± 0.009 ± 0.007
• A_CP(B^±→K^±K^±π^-) = -0.123 ± 0.017 ± 0.012 ± 0.007

In addition, a measurement of the forward-backward asymmetry (A_FB) of the light meson in the pp rest frame are measured to be

• A_FB(ppK⁺, m_pp < 2.85 GeV/c²) = 0.495 ± 0.012(stat) ± 0.007(syst)
• A_FB(ppπ⁺, m_pp < 2.85 GeV/c²) = -0.409 ± 0.033(stat) ± 0.006(syst)

and the branching fraction of the decay B⁺→Λ(1520)p is measured to be

• ℬℛ (B⁺→Λ(1520)p) = (3.15 ± 0.48(stat) ± 0.07(syst) ± 0.26(BF))×10^-7

where BF denotes the uncertainty on secondary branching fractions.

The phase space of three-body decays is the Dalitz plot, and its complete understanding is achieved by a complex amplitude analysis. However, such an amplitude analysis is model dependent. The CBPF group proposed in 2009 a model-independent method for a CP anisotropy measurement in the Dalitz plot. This "Mirandizing" method performs a direct measurement of the diference between particles and antiparticles in the Dalitz plot. Although qualitative, the method can be used as a guide to locate the decay channels and the Dalitz plot regions with large asymmetry, thus aiding the choice of a future amplitude analysis model.

 

Irina Nasteva and Fernando Rodrigues
Last update: April 8, 2015

 
 
 

Run2 analyses page
List of ARTICLES related to this topic: click here. ←Last Update: October 4, 2013

List of THESIS related to this topic: click here. ←Last Update: April 13, 2015

 
Results from LHCb Run I dataset (2009 → 2012)

• Measurements of CP violation in the three-body phase space of charmless B^± decays
      (LHCb-PAPER-2014-044, LHCb-ANA-2014-050, TWiki, BnoC WG database, August 2014)
      arXiv:1408.5373
      Phys.Rev.D90, 112004 (2014),     DOI:10.1103/PhysRevD.90.112004
  
  

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• Evidence of CP violation in B⁺→ppK⁺
      (LHCb-PAPER-2014-034, LHCb-ANA-2014-023, TWiki, July 2014)
      arXiv:1407.5907
      Phys.Rev.Lett.113, 141801 (2014),     DOI:10.1103/PhysRevLett.113.141801
  
  

  ---

• Measurement of CP violation in the phase space of B^±→K⁺K^-π^± and B^±→π⁺π^-π^± decays
      (LHCb-PAPER-2013-051, LHCb-ANA-2013-052, TWiki, October 2013)
      arXiv:1310.4740
      Phys.Rev.Lett.112, 011801 (2014),     DOI:10.1103/PhysRevLett.112.011801
  
  

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• Studies of the decays B⁺ → pp̅ h⁺ and observation of B⁺ → Λ̅(1520)p
      (LHCb-PAPER-2013-031, LHCb-ANA-2013-033, TWiki, July 2013)
      arXiv:1307.6165
      Phys.Rev.D88, 052015 (2013)
  
  

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• Measurement of CP violation in the phase space of B^±→K^±π⁺π^- and B^±→K^±K⁺K^- decays (Editor' suggestion of PRL v111)
      (LHCb-PAPER-2013-027, LHCb-ANA-2013-029, TWiki, June 2013)
      arXiv:1306.1246
      Phys.Rev.Lett.111, 101801 (2013)
  
  

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• Evidence for CP violation in B^±→π^±π^±π^- and B^±→K^±K^±π^- decays
      (LHCb-CONF-2012-028, LHCb-ANA-2012-077, TWiki, October 2012)
  
  

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• Evidence for CP violation in B^±→K^±π^±π^- and B^±→K^±K^±K^- decays
      (LHCb-CONF-2012-018, LHCb-ANA-2012-040, TWiki, July 2012)
  
  

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• Relative branching ratio measurements of charmless B^± decays to three hadrons
      (LHCb-CONF-2011-059, LHCb-ANA-2011-079, TWiki, November 2011)
  
  

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Current members

  Ignacio Bediaga¹, Ana Cavalcante¹, Melissa Cruz⁴, Carla Gobel⁴, Adlene Hicheur², Jussara Miranda¹, Andre Massafferri¹, Jose Helder², Juan Otalora², Alvaro Gomes³, Irina Nasteva², Alberto Reis¹, Fernando Rodrigues², Jeremy Dalseno⁵, Jonas Rademacker⁵, Daniel O'Hanlon⁶, Thomas Latham⁶, Timothy Gershon⁶, John Back⁶,

Institutes

  ¹ Centro Brasileiro de Pesquisas Físicas;
  ² Universidade Federal do Rio de Janeiro;
  ³ Universidade Federal do Triângulo Mineiro;
  ⁴ Universidade Católica do Rio de Janeiro;
  ⁵ University of Bristol;
  ⁶ University of Warwick;
 

Group meeting

  Wednesday at 15:00 (BRT/BRST) -- Vidyo

Organization

 

Analysis/Service	Contact
RunI: AmAn Kpipi	F. Rodrigues,   J. Helder
RunI: AmAn KKK	A. Reis,   I. Nasteva,   J. Otalora
RunI: AmAn pipipi (click here to go to the TWiki)	J. Miranda,   A. Gomes,   F. Rodrigues,  Warwick and Bristol groups
RunI: AmAn KKpi (click here to go to the TWiki)	M. Cruz,   C. Gobel
Run I: BR K→Khh	A. Cavalcante,   L. Soares
RunII: Trigger	UNDER DISCUSSION
RunII: Stripping	UNDER DISCUSSION
Ntp. generation	A. Gomes,   L. Soares

Internal Information (restricted access)

  >>> Tasks and services <<<

• Charged Charmless Bu→hhh Analysis Page(main page)
  
• Rio Group Bu→hhh Analysis Page (group page)
    ↳ Rio Group slides click here
    ↳ SVN Repositories Info click here
  

• LHCb workshop on multi-body decays of B and D mesons (Event - Jul 27, 2015)
  
• XXXV ENFPC [J. Otalora] (Slides - Sep 17, 2014)
  
• 3rd Implications of LHCb [I. Nasteva] (Slides - Oct 16, 2013)
  
• WIN 2013 [A. Hicheur] (Slides - Sep 17, 2013)
  
• FPCP 2013 [J. H. Lopes] (Poster - May 20, 2013)
  
• FPCP 2013 [I. Nasteva] (Slides - May 20, 2013) --- arXiv:1308.0740
  
• LISHEP 2013 [F. Rodrigues] (Slides - Mar 20, 2013)
  
• RETINHA24 2012 [F. Rodrigues] (Slides - Dec 04, 2012)
  
• CKM 2012 [J. Miranda] (Slides - Sep 30, 2012) --- arXiv:1301.0283
  
• ICHEP 2012 [F. Rodrigues] (Slides - Jul 7, 2012) --- PoS(ICHEP2012)248
  

• Undergraduate Laboratory Experiment: Measuring Matter Antimatter Asymmetries at the Large Hadron Collider
  (using B→3h data)
• Matéria e antimatéria: uma relação não muito simétrica
  (Informe CBPF - November 18, 2014)
  
• At IF-USP [I. Bediaga] (Slides - Aug 29, 2013)
  
• Charmless baryonic B decays
  (CERN Courier - Aug 19, 2013)
  
• Back From Hibernation, and a Puzzling Asymmetry
  (Quantum Diaries - March 4, 2013)
  
• Large CP-violation effects appear in three-body B decays
  (CERN Courier - Nov 6, 2012)
  
• Matter antimatter asymmetry in three-body charmless B decays becomes more and more interesting
  (LHCb public site - Oct 3, 2012 )
  
• (Video) Evidence of CP violation in B→hhh charmless decays
  (LHC Seminar [A. Gomes] - WebCast - Oct 2, 2012)
  
• Assimetrias em partículas podem explicar por que a matéria prevalece sobre a antimatéria no universo
  (CBPF news - Jul 18, 2012)
  
• So many attempts, so little luck
  (Quantum Diaries - Jul 8, 2012)
  
• Evidence for matter antimatter asymmetry in three-body charmless B decays
  (LHCb public site - Jul 7, 2012 (2))
  
• Matter-antimatter puzzle: LHCb improves resolution
  ( CERN Bulletin (Issue No. 28-29/2012) - Jul 2, 2012)