arxiv: 2604.16960 · v1 · submitted 2026-04-18 · ✦ hep-ex

Recognition: unknown

Flavour changing charged current decays at LHCb

Biljana Mitreska

Authors on Pith no claims yet

Pith reviewed 2026-05-10 06:59 UTC · model grok-4.3

classification ✦ hep-ex

keywords LHCbsemileptonic decaysbranching fractionform factorsb-hadron decaysLambda baryonB mesoncharged current

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The pith

LHCb has measured the branching fraction for the Lambda baryon semileptonic decay to proton muon antineutrino and extracted form factor parameters from the B zero to D star plus muon neutrino decay.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper presents LHCb measurements of the branching fraction in the decay Lambda to proton muon antineutrino and form factor parameters from B zero to D star plus muon neutrino decays. These semileptonic b-hadron decays occur via charged-current weak interactions and benefit from large branching fractions together with reliable calculations of the hadronic matrix elements. The results supply experimental inputs for determining CKM parameters, studying b-hadron production, and searching for new physics effects through form factors and branching ratio ratios. A reader cares because precise values here can reveal inconsistencies with Standard Model expectations if new physics is at work.

Core claim

LHCb measurements of the branching fraction in Λ → p μ⁻ ν̄_μ and form factor parameters with B⁰ → D^{*+} μ⁻ ν_μ decays are presented. Semileptonic b-hadron decays proceed via charged-current interactions and provide powerful probes for testing the Standard Model and searching for New Physics effects, with advantages including large branching fractions and reliable calculations of the hadronic matrix elements. Several features can be studied, such as the ratios of branching fractions, CKM parameters, properties of b-hadron production, form factor parameters and New Physics Wilson coefficients.

What carries the argument

The branching fraction measurement for the Lambda decay and the extraction of hadronic form factor parameters from the B meson decay, which together serve as the experimental inputs for Standard Model tests and new physics searches in charged-current processes.

If this is right

The branching fraction supplies an input for extracting CKM matrix elements from semileptonic decays.
Form factor parameters enable direct comparisons with lattice QCD calculations.
Branching ratio ratios involving these modes can test lepton flavor universality.
The data improves knowledge of b-hadron production cross sections at the LHC.
The results can be used to place constraints on new physics Wilson coefficients.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

Combining these measurements with other LHCb semileptonic results could tighten overall constraints on charged-current couplings.
Any tension with theoretical predictions might guide model-building for new physics that affects only certain quark transitions.
Higher-luminosity LHCb runs could extend the precision enough to probe subtle new physics contributions below current sensitivity.

Load-bearing premise

The measurements depend on accurate simulation of the detector response, precise background subtraction, and the chosen parametrization of the hadronic form factors.

What would settle it

An independent measurement of the branching fraction for Λ → p μ⁻ ν̄_μ that lies outside the uncertainty range reported by LHCb would require revision of the result.

read the original abstract

Semileptonic $b$-hadron decays proceed via charged-current interactions and provide powerful probes for testing the Standard Model and searching for New Physics effects. The advantages of studying such decays include the large branching fractions and reliable calculations of the hadronic matrix elements. Several features can be studied, such as the ratios of branching fractions, CKM parameters, properties of $b$-hadron production, form factor parameters and New Physics Wilson coefficients. In this contribution, LHCb measurements of branching fraction in $\Lambda \to p \mu^{-} \bar{\nu}_{\mu}$ and form factor parameters with $B^0 \to D^{*+} \mu^{-} \nu_{\mu}$ decays are presented.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

This is a short LHCb conference contribution that states two semileptonic measurements are presented but supplies almost no numbers, methods, or results.

read the letter

The main point is that this note from Biljana Mitreska summarizes LHCb work on the branching fraction of Λ → p μ⁻ ν̄_μ and the form-factor parameters in B⁰ → D^{*+} μ⁻ ν_μ. It frames these as useful channels because of their large branching fractions and the fact that the hadronic matrix elements can be calculated reliably. The text lists the usual observables one can extract: branching-fraction ratios, CKM parameters, production properties, form factors, and possible new-physics Wilson coefficients. That framing is standard and accurate for semileptonic b decays.

Referee Report

1 major / 2 minor

Summary. This conference contribution outlines LHCb studies of semileptonic b-hadron decays proceeding via charged currents. It states that measurements of the branching fraction for Λ → p μ⁻ ν̄_μ and form factor parameters in B⁰ → D^{*+} μ⁻ ν_μ are presented, along with discussion of their utility for testing the Standard Model, extracting CKM parameters, and searching for New Physics.

Significance. If the reported measurements are new, precise, and correctly extracted, they would add to the experimental constraints on hadronic form factors and branching fractions in charged-current b decays, where theoretical matrix elements are relatively reliable. Such results can help test lepton flavour universality and bound Wilson coefficients for possible New Physics contributions.

major comments (1)

[Abstract / main text] The manuscript states that the branching fraction and form factor parameters 'are presented,' yet the text contains no numerical results, uncertainties, data samples, selection criteria, fit procedures, or figures/tables. This directly undermines the central claim of the contribution (see the final sentence of the provided text).

minor comments (2)

The text is very general and does not reference the integrated luminosity, run periods, or specific LHCb detector performance details needed to contextualize the measurements.
Notation for the antineutrino is written as ν̄_μ; ensure consistent typesetting throughout if the manuscript is expanded.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for the careful reading and constructive feedback on this conference contribution. We address the major comment below and agree that revisions are needed to better align the text with its content.

read point-by-point responses

Referee: [Abstract / main text] The manuscript states that the branching fraction and form factor parameters 'are presented,' yet the text contains no numerical results, uncertainties, data samples, selection criteria, fit procedures, or figures/tables. This directly undermines the central claim of the contribution (see the final sentence of the provided text).

Authors: We agree with the referee that the current text does not include numerical results, uncertainties, data samples, selection criteria, fit procedures, or supporting figures/tables, which makes the phrasing 'are presented' inaccurate for a standalone document. This short conference contribution was intended as an overview of LHCb's program on charged-current semileptonic decays rather than a full report of the analyses. We will revise the manuscript to change the final sentence to indicate that the measurements 'are discussed' or 'will be presented in forthcoming publications,' and we will add a brief reference to the relevant LHCb papers or public notes where the full details can be found. If the proceedings format permits additional space, we will also include a summary of the key results and one illustrative figure. revision: yes

Circularity Check

0 steps flagged

No significant circularity in experimental measurement report

full rationale

This is a conference contribution that reports LHCb experimental measurements of the branching fraction for Λ → p μ⁻ ν̄_μ and form-factor parameters in B⁰ → D^{*+} μ⁻ ν_μ extracted from collision data. No derivation chain, first-principles prediction, or fitted model is presented whose output reduces by construction to author-defined inputs, self-citations, or ansatzes. The results are data-driven with standard detector simulation and background techniques whose validity does not depend on the reported numerical values, rendering the presentation self-contained.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Only the abstract is available; no explicit free parameters, axioms, or invented entities are described beyond standard assumptions of the Standard Model and LHCb detector modeling.

pith-pipeline@v0.9.0 · 5402 in / 1050 out tokens · 36623 ms · 2026-05-10T06:59:34.081879+00:00 · methodology

discussion (0)

Reference graph

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