Differential branching fraction and angular analysis of Λ(formula presented.)decays

The Lhcb Collaboration

Research output: Contribution to journalArticle

51 Citations (Scopus)

Abstract

Abstract: The differential branching fraction of the rare decay Λb 0 → Λμ+μ is measured as a function of q2, the square of the dimuon invariant mass. The analysis is performed using proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb−1, collected by the LHCb experiment. Evidence of signal is observed in the q2 region below the square of the J/ψ mass. Integrating over 15 <q2<20 GeV2/c4 the differential branching fraction is measured asdℬ(formula presented.)±0.03±0.27×10−7 GeV2/c4−1,$$ \mathrm{d}\mathrm{\mathcal{B}}\left({\varLambda}_b^0\to \varLambda {\mu}^{+}{\mu}^{-}\right)/d{q}^2=\left({1.18}_{-0.08}^{+0.09}\pm 0.03\pm 0.27\right)\times {10}^{-7}{\left({\mathrm{GeV}}^2/{c}^4\right)}^{-1}, $$where the uncertainties are statistical, systematic and due to the normalisation mode, Λb 0 → J/ψΛ, respectively. In the q2 intervals where the signal is observed, angular distributions are studied and the forward-backward asymmetries in the dimuon (AFB ) and hadron (AFB h) systems are measured for the first time. In the range 15 <q2<20 GeV2/c4 they are found to be(formula presented.)=−0.29±0.07stat±0.03syst.$$ \begin{array}{l}{A}_{\mathrm{FB}}^{\ell }=-0.05\pm 0.09\left(\mathrm{stat}\right)\pm 0.03\left(\mathrm{syst}\right)\;\mathrm{and}\hfill \\ {}{A}_{\mathrm{FB}}^h=-0.29\pm 0.07\left(\mathrm{stat}\right)\pm 0.03\left(\mathrm{syst}\right).\hfill \end{array} $$[Figure not available: see fulltext.]

Original languageEnglish (US)
Article number115
JournalJournal of High Energy Physics
Volume2015
Issue number6
DOIs
StatePublished - Jun 27 2015

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protons
decay
angular distribution
luminosity
asymmetry
intervals
collisions

Keywords

  • Bphysics
  • Branching fraction
  • Flavour Changing Neutral Currents
  • Hadron-Hadron Scattering
  • Rare decay

ASJC Scopus subject areas

  • Nuclear and High Energy Physics

Cite this

Differential branching fraction and angular analysis of Λ(formula presented.)decays. / The Lhcb Collaboration.

In: Journal of High Energy Physics, Vol. 2015, No. 6, 115, 27.06.2015.

Research output: Contribution to journalArticle

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abstract = "Abstract: The differential branching fraction of the rare decay Λb 0 → Λμ+μ− is measured as a function of q2, the square of the dimuon invariant mass. The analysis is performed using proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb−1, collected by the LHCb experiment. Evidence of signal is observed in the q2 region below the square of the J/ψ mass. Integrating over 15 2<20 GeV2/c4 the differential branching fraction is measured asdℬ(formula presented.)±0.03±0.27×10−7 GeV2/c4−1,$$ \mathrm{d}\mathrm{\mathcal{B}}\left({\varLambda}_b^0\to \varLambda {\mu}^{+}{\mu}^{-}\right)/d{q}^2=\left({1.18}_{-0.08}^{+0.09}\pm 0.03\pm 0.27\right)\times {10}^{-7}{\left({\mathrm{GeV}}^2/{c}^4\right)}^{-1}, $$where the uncertainties are statistical, systematic and due to the normalisation mode, Λb 0 → J/ψΛ, respectively. In the q2 intervals where the signal is observed, angular distributions are studied and the forward-backward asymmetries in the dimuon (AFB ℓ) and hadron (AFB h) systems are measured for the first time. In the range 15 2<20 GeV2/c4 they are found to be(formula presented.)=−0.29±0.07stat±0.03syst.$$ \begin{array}{l}{A}_{\mathrm{FB}}^{\ell }=-0.05\pm 0.09\left(\mathrm{stat}\right)\pm 0.03\left(\mathrm{syst}\right)\;\mathrm{and}\hfill \\ {}{A}_{\mathrm{FB}}^h=-0.29\pm 0.07\left(\mathrm{stat}\right)\pm 0.03\left(\mathrm{syst}\right).\hfill \end{array} $$[Figure not available: see fulltext.]",
keywords = "Bphysics, Branching fraction, Flavour Changing Neutral Currents, Hadron-Hadron Scattering, Rare decay",
author = "{The Lhcb Collaboration} and R. Aaij and B. Adeva and M. Adinolfi and A. Affolder and Z. Ajaltouni and S. Akar and J. Albrecht and F. Alessio and M. Alexander and S. Ali and G. Alkhazov and {Alvarez Cartelle}, P. and Alves, {A. A.} and S. Amato and S. Amerio and Y. Amhis and L. An and L. Anderlini and J. Anderson and M. Andreotti and Andrews, {J. E.} and Appleby, {R. B.} and {Aquines Gutierrez}, O. and F. Archilli and A. Artamonov and M. Artuso and Marina Artuso and G. Auriemma and M. Baalouch and S. Bachmann and Back, {J. J.} and A. Badalov and C. Baesso and W. Baldini and Barlow, {R. J.} and C. Barschel and S. Barsuk and W. Barter and V. Batozskaya and V. Battista and A. Bay and L. Beaucourt and J. Beddow and F. Bedeschi and I. Bediaga and Bel, {L. J.} and I. Belyaev and Blusk, {Steven Roy} and Tomasz Skwarnicki and Sheldon Stone",
year = "2015",
month = "6",
day = "27",
doi = "10.1007/JHEP06(2015)115",
language = "English (US)",
volume = "2015",
journal = "Journal of High Energy Physics",
issn = "1126-6708",
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T1 - Differential branching fraction and angular analysis of Λ(formula presented.)decays

AU - The Lhcb Collaboration

AU - Aaij, R.

AU - Adeva, B.

AU - Adinolfi, M.

AU - Affolder, A.

AU - Ajaltouni, Z.

AU - Akar, S.

AU - Albrecht, J.

AU - Alessio, F.

AU - Alexander, M.

AU - Ali, S.

AU - Alkhazov, G.

AU - Alvarez Cartelle, P.

AU - Alves, A. A.

AU - Amato, S.

AU - Amerio, S.

AU - Amhis, Y.

AU - An, L.

AU - Anderlini, L.

AU - Anderson, J.

AU - Andreotti, M.

AU - Andrews, J. E.

AU - Appleby, R. B.

AU - Aquines Gutierrez, O.

AU - Archilli, F.

AU - Artamonov, A.

AU - Artuso, M.

AU - Artuso, Marina

AU - Auriemma, G.

AU - Baalouch, M.

AU - Bachmann, S.

AU - Back, J. J.

AU - Badalov, A.

AU - Baesso, C.

AU - Baldini, W.

AU - Barlow, R. J.

AU - Barschel, C.

AU - Barsuk, S.

AU - Barter, W.

AU - Batozskaya, V.

AU - Battista, V.

AU - Bay, A.

AU - Beaucourt, L.

AU - Beddow, J.

AU - Bedeschi, F.

AU - Bediaga, I.

AU - Bel, L. J.

AU - Belyaev, I.

AU - Blusk, Steven Roy

AU - Skwarnicki, Tomasz

AU - Stone, Sheldon

PY - 2015/6/27

Y1 - 2015/6/27

N2 - Abstract: The differential branching fraction of the rare decay Λb 0 → Λμ+μ− is measured as a function of q2, the square of the dimuon invariant mass. The analysis is performed using proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb−1, collected by the LHCb experiment. Evidence of signal is observed in the q2 region below the square of the J/ψ mass. Integrating over 15 2<20 GeV2/c4 the differential branching fraction is measured asdℬ(formula presented.)±0.03±0.27×10−7 GeV2/c4−1,$$ \mathrm{d}\mathrm{\mathcal{B}}\left({\varLambda}_b^0\to \varLambda {\mu}^{+}{\mu}^{-}\right)/d{q}^2=\left({1.18}_{-0.08}^{+0.09}\pm 0.03\pm 0.27\right)\times {10}^{-7}{\left({\mathrm{GeV}}^2/{c}^4\right)}^{-1}, $$where the uncertainties are statistical, systematic and due to the normalisation mode, Λb 0 → J/ψΛ, respectively. In the q2 intervals where the signal is observed, angular distributions are studied and the forward-backward asymmetries in the dimuon (AFB ℓ) and hadron (AFB h) systems are measured for the first time. In the range 15 2<20 GeV2/c4 they are found to be(formula presented.)=−0.29±0.07stat±0.03syst.$$ \begin{array}{l}{A}_{\mathrm{FB}}^{\ell }=-0.05\pm 0.09\left(\mathrm{stat}\right)\pm 0.03\left(\mathrm{syst}\right)\;\mathrm{and}\hfill \\ {}{A}_{\mathrm{FB}}^h=-0.29\pm 0.07\left(\mathrm{stat}\right)\pm 0.03\left(\mathrm{syst}\right).\hfill \end{array} $$[Figure not available: see fulltext.]

AB - Abstract: The differential branching fraction of the rare decay Λb 0 → Λμ+μ− is measured as a function of q2, the square of the dimuon invariant mass. The analysis is performed using proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb−1, collected by the LHCb experiment. Evidence of signal is observed in the q2 region below the square of the J/ψ mass. Integrating over 15 2<20 GeV2/c4 the differential branching fraction is measured asdℬ(formula presented.)±0.03±0.27×10−7 GeV2/c4−1,$$ \mathrm{d}\mathrm{\mathcal{B}}\left({\varLambda}_b^0\to \varLambda {\mu}^{+}{\mu}^{-}\right)/d{q}^2=\left({1.18}_{-0.08}^{+0.09}\pm 0.03\pm 0.27\right)\times {10}^{-7}{\left({\mathrm{GeV}}^2/{c}^4\right)}^{-1}, $$where the uncertainties are statistical, systematic and due to the normalisation mode, Λb 0 → J/ψΛ, respectively. In the q2 intervals where the signal is observed, angular distributions are studied and the forward-backward asymmetries in the dimuon (AFB ℓ) and hadron (AFB h) systems are measured for the first time. In the range 15 2<20 GeV2/c4 they are found to be(formula presented.)=−0.29±0.07stat±0.03syst.$$ \begin{array}{l}{A}_{\mathrm{FB}}^{\ell }=-0.05\pm 0.09\left(\mathrm{stat}\right)\pm 0.03\left(\mathrm{syst}\right)\;\mathrm{and}\hfill \\ {}{A}_{\mathrm{FB}}^h=-0.29\pm 0.07\left(\mathrm{stat}\right)\pm 0.03\left(\mathrm{syst}\right).\hfill \end{array} $$[Figure not available: see fulltext.]

KW - Bphysics

KW - Branching fraction

KW - Flavour Changing Neutral Currents

KW - Hadron-Hadron Scattering

KW - Rare decay

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U2 - 10.1007/JHEP06(2015)115

DO - 10.1007/JHEP06(2015)115

M3 - Article

AN - SCOPUS:84973444390

VL - 2015

JO - Journal of High Energy Physics

JF - Journal of High Energy Physics

SN - 1126-6708

IS - 6

M1 - 115

ER -