Observation of the Decay $B \to K \ell^{+} \ell^{-}$

et al. (the Belle Collaboration); K. Abe

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Observation of the Decay $B \to K \ell^{+} \ell^{-}$

K. Abe, et al. (The Belle Collaboration)

High Energy Physics - Experiment · Submitted 18 Sep 2001

abstract compiled · 2026-09-23 · no language-model review

The authors' main claim We observe the decay process $B\to K\ell^+\ell^- (\ell = e, \mu )$, for the first time, with a branching fraction of ${\cal B}(B \to K \ell^{+} \ell^{-}) = (0.75^{+0.25}_{-0.21} \pm 0.09) \times 10^{-6}$.

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Compiled by classifier-1.13-20260917 via OpenRouter, question bank abstract-p1-20260923, 2026-09-23: 1 request, 2,577 input tokens, $0.0001 reported.

What the abstract itself states, as probabilities: claims first 0.91 · states limitation 0.16 · human participants 0.01 · controlled comparison 0.03 · randomized assignment 0.01 · states quantitative result 0.99 · compares with prior results 0.07 · mentions code or data availability 0.02.

The abstract, sentence by sentence

arXiv listing abstract v2. Results and the main claim are underlined; show every role.

We report a search for the flavor-changing neutral current decay $B \to K^{(*)} \ell^{+} \ell^{-}$ using a 29.1 fb${}^{-1}$ data sample accumulated at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB $e^{+}e^{-}$ storage ring. We observe the decay process $B\to K\ell^+\ell^- (\ell = e, \mu )$, for the first time, with a branching fraction of ${\cal B}(B \to K \ell^{+} \ell^{-}) = (0.75^{+0.25}_{-0.21} \pm 0.09) \times 10^{-6}$.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#	sentence	role	the authors' own work	states the main conclusion	strength
s0	We report a search for the flavor-changing neutral current decay $B \to K^{(*)} \ell^{+} \ell^{-}$ using a 29.1 fb${}^{-1}$ data sample accumulated at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB $e^{+}e^{-}$ storage ring.	method 0.87	0.92	0.04	asserted 0.84
s1	We observe the decay process $B\to K\ell^+\ell^- (\ell = e, \mu )$, for the first time, with a branching fraction of ${\cal B}(B \to K \ell^{+} \ell^{-}) = (0.75^{+0.25}_{-0.21} \pm 0.09) \times 10^{-6}$.	result 1.00	0.97	0.90	asserted 1.00

What kind of paper the classifier reports this is: empirical study 1.00 · evidence from observation or experiment 0.89.

What was examined, and what was not

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arXiv listing abstract v2

not examined

full text
figures and tables
references and citing sentences
relations to other papers

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P abstract

not run

S sections
T body sentences
C citations
R cross-paper relations

Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

The paper

Original abstract

We report a search for the flavor-changing neutral current decay $B \to K^{(*)} \ell^{+} \ell^{-}$ using a 29.1 fb${}^{-1}$ data sample accumulated at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB $e^{+}e^{-}$ storage ring. We observe the decay process $B\to K\ell^+\ell^- (\ell = e, \mu )$, for the first time, with a branching fraction of ${\cal B}(B \to K \ell^{+} \ell^{-}) = (0.75^{+0.25}_{-0.21} \pm 0.09) \times 10^{-6}$.

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References

Forward citations

Cited by 4 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

Observation of a resonance in $B^+ \to K^+ \mu^+\mu^-$ decays at low recoil
hep-ex 2013-07 accept novelty 7.0 of 10

A greater-than-six-sigma resonance at 4191 MeV (width 65 MeV) in B+ to K+ mu+ mu- is identified with the psi(4160), giving the first observation of B+ to psi(4160) K+ and psi(4160) to mu+ mu-.
Dark-Matter Electric and Magnetic Dipole Moments
astro-ph 2004-06 accept novelty 7.0 of 10

A neutral Dirac dark matter particle with an electric or magnetic dipole moment up to about 3e-16 e cm and a mass between an MeV and a few GeV survives all known laboratory, cosmological, and astrophysical constraints.
Minimal Flavour Violation: an effective field theory approach
hep-ph 2002-07 accept novelty 7.0 of 10

Minimal Flavour Violation is formulated as a spurion effective field theory, yielding a complete dimension-six operator basis, bounds of 1 to 10 TeV on their scales, and a systematic resummation of tan(beta)-enhanced ...
Weak Annihilation Contribution to Angular Observables in $B_{c}^+\to D^{\ast+}\ell^{+}\ell^{-}$ Decays
hep-ph 2026-02 unverdicted novelty 4.0 of 10

Weak annihilation contributions are sizable in B_c^+ to D^{*+} lepton pair decays and must be included to obtain reliable Standard Model predictions for angular observables.

How the literature uses it

8 arXiv papers cite this in 9 sentences

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

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Compares with it 1 paper

For comparison, the theoretical and experimental results also are presented , such as the PDG [ref] , HFLAV [ref] , HPQCD'13(22) [ref] , LCSR'00(06) [ref] , RQM'02 [ref] , BHDW'11 [ref] , PQCD'12 [ref] , MILC'15 [ref] , (Majorana neutrino exchange)MNE-18 [ref] , BaBar-08(12,16) [ref] , CDF-11 [ref] , Belle'02(09,19) [ref] , and LHCb'12(14C,16) [ref] .

The rare decay $B^+ \to K^+\ell^+\ell^-(\nu\bar{\nu})$ under the QCD sum rules approach · Numerical Analysis · 1.00

Cites it as background 6 papers

In addition, the BaBar [ref] , the CDF [ref] , the Belle [ref] , the CMS [ref] , and the LHCb [ref] Collaborations also conducted researches on the $B^+→K^+ℓ^+ℓ^-$ decays for exploring various physical observables, such as the differential branching fractions, the forward-backward asymmetries, the flat term and the isospin asymmetries, etc.

The rare decay $B^+ \to K^+\ell^+\ell^-(\nu\bar{\nu})$ under the QCD sum rules approach · Introduction · 0.95
The semileptonic $b→sℓ^+ℓ^-$ decays $ℓ^+ℓ^-$ and $ℓ^+ℓ^-$ were first observed by the Belle Collaboration [ref] .

Flavor Anomalies in Heavy Quark Decays · Decay rates · 0.91
The $b →s ℓℓ̅$ processes have been explored widely through the $B →K^(*)ℓℓ̅$ decays [ref] .

Weak Annihilation Contribution to Angular Observables in $B_{c}^+\to D^{\ast+}\ell^{+}\ell^{-}$ Decays · Introduction · 1.00

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