Lepton Mass Effects and Angular Observables in \(\Lambda _b \rightarrow \Lambda (\rightarrow P \pi ) \ell ^+\ell ^-\)

  • Ria SainEmail author
Conference paper
Part of the Springer Proceedings in Physics book series (SPPHY, volume 234)


The flavor changing rare decay \(B\rightarrow {K^{\!*}}(\rightarrow K\pi )\ell ^+\ell ^-\) is one of the most studied modes due to its sensitivity to physics beyond the standard model and several discrepancies have come to light among the plethora of observables that are measured. In this work we revisit the analogous baryonic decay mode \(\Lambda _{b}\rightarrow \Lambda (\rightarrow p\pi ) \ell ^{+}\ell ^{-}\) and we present a complete set of 10 angular observables that can be measured using this decay mode. Our calculations are done retaining the finite lepton mass so that the signal of lepton non-universality observed in \(B\rightarrow {K^{\!*}}\ell ^+\ell ^-\) can be corroborated by the corresponding baryonic decay mode. We show that due to the parity violating nature of the subsequent \(\Lambda \rightarrow p\pi \) decay there exists at least one angular asymmetry that is non-vanishing in the large recoil limit unlike the case in \(B\rightarrow {K^{\!*}}\ell ^+\ell ^-\) decay mode, making it particularly sensitive to new physics that violates lepton flavor universality.



We would like to thank Prof. Rahul Sinha and Shibasis Roy for collaborating in the paper [7] and for giving valuable suggestions for the presentation.


  1. 1.
    R. Aaij et al., LHCb collaboration. JHEP 1708, 055 (2017)ADSCrossRefGoogle Scholar
  2. 2.
    S. Bifani (on behalf of the LHCb Collab.), CERN seminar on April 18, 2017Google Scholar
  3. 3.
    R. Aaij et al., [LHCb Collab.], Phys. Rev. Lett. 113, 151601 (2014)Google Scholar
  4. 4.
    T. Gutsche, M.A. Ivanov, J.G. Körner, V.E. Lyubovitskij, P. Santorelli, Phys. Rev. D 87, 074031 (2013). arXiv:1301.3737 [hep-ph]
  5. 5.
    P. Böer, T. Feldmann, D. van Dyk, JHEP 1501, 155 (2015). arXiv:1410.2115 [hep-ph]
  6. 6.
    T. Blake, M. Kreps, JHEP 1711, 138 (2017). arXiv:1710.00746 [hep-ph]
  7. 7.
    S. Roy, R. Sain, R. Sinha, Phys. Rev. D 96, 11, 116005 (2017). [hep-ph]
  8. 8.
    Y.M. Wang, Y.L. Shen, C.D. Lu, Phys. Rev. D 80, 074012 (2009). arXiv:0907.4008 [hep-ph]
  9. 9.
    W. Wang, Phys. Lett. B 708, 119 (2012). arXiv:1112.0237 [hep-ph]
  10. 10.
    T. Feldmann and M. W. Y. Yip, Phys. Rev. D 85, 014035 (2012) Erratum. Phys. Rev. D 86, 079901 (2012). arXiv:1111.1844 [hep-ph]
  11. 11.
    T. Mannel, Y.M. Wang, JHEP 1112, 067 (2011). arXiv:1111.1849 [hep-ph]

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© Springer Nature Switzerland AG 2019

Authors and Affiliations

  1. 1.The Institute of Mathematical SciencesChennaiIndia
  2. 2.Homi Bhabha National Institute Training School ComplexMumbaiIndia

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