New Physics in inclusive bar{B} to X_c ell bar{ν} decays
Pith reviewed 2026-05-10 04:10 UTC · model grok-4.3
The pith
A global fit to all data on inclusive anti-B to Xc lepton anti-nu decays finds no significant preference for new physics and produces Wilson coefficient bounds competitive with exclusive modes.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
We present the first global phenomenological fit of inclusive B to Xc lepton nu bar decays to all available experimental data allowing for generic dimension-six New Physics interactions in the Weak Effective Theory. The fit includes both New Physics Wilson coefficients and non-perturbative QCD parameters. New Physics contributions are calculated including power corrections up to O(Lambda_QCD^3/m_b^3) and perturbative QCD corrections up to O(alpha_s). We find no significant preference for New Physics and obtain bounds on the size of the relevant Wilson Coefficients competitive with those coming from exclusive modes.
What carries the argument
Global fit of inclusive decay data that simultaneously varies dimension-six new physics Wilson coefficients in the weak effective theory together with QCD parameters, using calculations that include O(Lambda_QCD^3/m_b^3) power corrections and O(alpha_s) perturbative terms.
If this is right
- Any new physics model proposed to explain tensions in exclusive b to c decays must also remain consistent with the inclusive data under the same effective theory.
- The inclusive bounds can be combined with exclusive bounds to produce stronger overall constraints on the Wilson coefficients.
- Improved experimental precision on inclusive observables in the future will directly tighten the limits on new physics without requiring changes to the theoretical framework.
- The absence of new physics signals indicates that current data in these channels are well described by the standard model plus small higher-order corrections.
Where Pith is reading between the lines
- A joint analysis of inclusive and exclusive data sets could exclude larger portions of new physics parameter space than either analysis alone.
- If future data reveal deviations, it may become necessary to extend the fit to include dimension-eight operators or additional non-perturbative effects.
- The same global-fit methodology could be applied to other inclusive heavy-quark decay channels to provide cross-checks on new physics searches.
- This work underscores that inclusive decays serve as a valuable complementary probe to exclusive modes when testing the completeness of the standard model description.
Load-bearing premise
That dimension-six operators in the weak effective theory together with the included power corrections up to order Lambda_QCD cubed over m_b cubed and perturbative terms up to alpha_s are enough to describe any new physics contributions across the observables.
What would settle it
A high-precision measurement of an inclusive decay rate, lepton spectrum, or moment that deviates significantly from both standard model predictions and the best-fit new physics model, and cannot be accommodated by reasonable adjustments to the fitted parameters or corrections.
read the original abstract
We present the first global phenomenological fit of inclusive $\bar B\to X_c\ell\bar\nu$ observables to all available experimental data allowing for generic dimension-six New Physics interactions in the Weak Effective Theory. The fit includes both New Physics Wilson coefficients and non-perturbative QCD parameters. New Physics contributions are calculated including power corrections up to $\mathcal O(\Lambda_{\rm QCD}^3/m_b^3)$ and perturbative QCD corrections up to $\mathcal O(\alpha_s)$. We find no significant preference for New Physics and obtain bounds on the size of the relevant Wilson Coefficients competitive with those coming from exclusive modes.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript presents the first global phenomenological fit of inclusive B-bar to X_c lepton anti-nu observables to all available experimental data, allowing for generic dimension-six New Physics interactions in the Weak Effective Theory. The fit simultaneously varies New Physics Wilson coefficients and non-perturbative QCD parameters, incorporating power corrections up to O(Lambda_QCD^3/m_b^3) and perturbative QCD corrections up to O(alpha_s). The central result is that there is no significant preference for New Physics, with derived bounds on the relevant Wilson coefficients competitive with those from exclusive decay modes.
Significance. If the result holds, this constitutes the first comprehensive global analysis of inclusive semileptonic b to c transitions that includes generic dim-6 NP operators while floating QCD parameters and including higher-order corrections. It provides a unified framework that can be directly compared to exclusive-channel constraints, potentially clarifying whether apparent tensions in the b sector are mode-dependent or indicative of broader new physics. The explicit inclusion of power and perturbative terms, together with the simultaneous fit, strengthens the robustness of the no-preference conclusion relative to earlier partial analyses.
major comments (1)
- The central claim of no significant NP preference rests on the global fit to experimental data. The manuscript should explicitly list the precise experimental inputs (datasets, observables, and any cuts) and the chi-squared definition in the section describing the fit procedure, as incomplete documentation of data selection would undermine reproducibility and the assessment of whether the bounds are truly competitive.
minor comments (2)
- Notation for the Wilson coefficients and the power-correction parameters should be standardized across equations and tables to avoid potential confusion between NP and QCD contributions.
- The abstract states that bounds are 'competitive' with exclusive modes; a direct numerical comparison table would strengthen this statement.
Simulated Author's Rebuttal
We thank the referee for their positive evaluation of our work and for the constructive suggestion regarding documentation of the fit procedure. We address the comment below and have revised the manuscript accordingly.
read point-by-point responses
-
Referee: The central claim of no significant NP preference rests on the global fit to experimental data. The manuscript should explicitly list the precise experimental inputs (datasets, observables, and any cuts) and the chi-squared definition in the section describing the fit procedure, as incomplete documentation of data selection would undermine reproducibility and the assessment of whether the bounds are truly competitive.
Authors: We agree that full transparency in the experimental inputs and chi-squared definition is important for reproducibility and for allowing readers to evaluate the competitiveness of the bounds. In the revised manuscript, we have added a new subsection (Section 3.2) to the fit procedure that explicitly tabulates all datasets and observables used, specifies the kinematic cuts applied in each measurement, and provides the precise mathematical definition of the chi-squared function, including how correlations between observables are incorporated. This addition directly addresses the concern without altering any numerical results. revision: yes
Circularity Check
No significant circularity; result follows from external data fit
full rationale
The paper conducts a global fit of inclusive B to X_c l nu observables to dim-6 WET operators, simultaneously varying NP Wilson coefficients and non-perturbative QCD parameters while including explicit O(Λ_QCD^3/m_b^3) power corrections and O(α_s) terms. The claim of no significant NP preference and competitive bounds arises directly from data compatibility within uncertainties, not from any self-definitional equation, fitted input renamed as prediction, or load-bearing self-citation chain. The OPE framework is applied uniformly to external experimental inputs without reducing the central result to its own assumptions by construction.
Axiom & Free-Parameter Ledger
free parameters (2)
- Wilson coefficients of dimension-six operators
- non-perturbative QCD parameters
axioms (2)
- domain assumption New physics can be parametrized by dimension-six operators in the Weak Effective Theory
- domain assumption Power corrections up to O(Lambda_QCD^3/m_b^3) and perturbative QCD corrections up to O(alpha_s) are adequate
Reference graph
Works this paper leans on
- [1]
-
[2]
A. Carvunis, P. Gambino, G. Finauri, M. Jung and S. M¨ achler, JHEP01, 037 (2026)
work page 2026
- [3]
-
[4]
B. Blok, L. Koyrakh, Mikhail A. Shifman, A. I. Vainshtein Phys. Rev. D49, 3356 (1994)
work page 1994
-
[5]
A. V. Manohar and M. B. Wise, Phys. Rev. D49, 1310 (1994)
work page 1994
- [6]
- [7]
- [8]
- [9]
-
[10]
M. Fael, M. Rahimi, K. Vos, JHEP02, 086 (2023)
work page 2023
-
[11]
M. Fael, F. Herren JHEP05, 287 (2024)
work page 2024
- [12]
- [13]
- [14]
-
[15]
D. Bigi, M. Bordone, P. Gambino, U. Haisch, A. Piccione JHEP11, 163 (2023)
work page 2023
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.