The Belle Collaboration has recently reported a measurement of the branching fraction for the semileptonic decay $ B^{-}\to\pi^{+}\pi^{-}\ell^{-}\bar\nu_\ell $ , with $ \ell=e $ or $\textit{μ}$. Using the newly available data across the full $ \pi\pi $ invariant-mass spectrum, we determine the non-resonant $ B\to\pi\pi $ transition form factors. We obtain a non-resonant branching fraction $ {\cal B}_N(B^{-}\to\pi^{+}\pi^{-}\ell^{-}\bar\nu_\ell)=(3.5\pm 1.4^{+4.3}_{-2.4})\times 10^{-5} $ . This result indicates that the non-resonant contribution can be comparable in magnitude to the resonant components and should not be treated as a negligible background in precision measurements. Our findings highlight the importance of dedicated experimental efforts at Belle II and LHCb to further probe the non-resonant contribution.

China

Yan-Li Wang

Xiao-Yu Hao

Yu-Kuo Hsiao

Semileptonic ${B^{-}\to\pi^{+}\pi^{-}\ell^{-}\bar\nu_\ell}$ decay over the full ${\pi\pi}$ invariant mass spectrum * Supported in part by the National Natural Science Foundation of China (12575101, 12175128)

Semileptonic $$b\rightarrow c\tau \bar{\nu }_{\tau }$$ decays are powerful probes of non-Standard-Model effects within an effective-field-theory (EFT) framework, but fully exploiting them in current and future data demands combinations that maximise sensitivity while controlling biases from Standard-Model-based modelling and from theory inputs that are shared, and therefore correlated, across analyses in different experiments. We present a first sensitivity study of a $\textit{combined}$ extraction of Wilson coefficients in $$\bar{B}\rightarrow D^{(*)}\tau \bar{\nu }_{\tau }$$ decays using LHCb- and Belle II-like analysis configurations. Detector simulations for signal and backgrounds are typically generated under Standard Model assumptions; if non-SM contributions are present, this can bias the fitted Wilson coefficients. In addition, hadronic inputs such as form-factor parameters of signal and background components are common across analyses, requiring a consistent treatment of fully correlated effects in combinations. To avoid repeating large-scale detector simulation for each EFT hypothesis, we use event-by-event reweighting to map simulated samples to arbitrary combinations of Wilson coefficients. We then compare a simultaneous fit across multiple $$\bar{B}\rightarrow D^{(*)}\tau \bar{\nu }_{\tau }$$ channels and datasets with a combination based on post-fit averages. Sharing Wilson coefficients and common form-factor parameters in the simultaneous fit reduces model-induced biases and improves sensitivity relative to independent fits, providing a robust and scalable strategy for precision EFT constraints in $$b\rightarrow c\tau \bar{\nu }_{\tau }$$ transitions using forthcoming LHCb and Belle II datasets.

Germany

Johannes Albrecht

Florian Bernlochner

Marco Colonna

Lorenz Gärtner

Switzerland

Abhijit Mathad

United Kingdom

Biljana Mitreska

Markus Prim

Ilias Tsaklidis

Joint LHCb–Belle II prospects to constrain new physics in $$B\rightarrow D^{(*)}\tau \nu $$

J.G. Wang

Z.C. Li

Z.Y. Zhang

Z.G. Gan

Japan

A.N. Andreyev

M.H. Huang

L. Ma

M.M. Zhang

H.B. Yang

C.L. Yang

Y.H. Qiang

Z.H. Li

X.Y. Huang

G. Xie

L. Zhu

H. Zhou

X. Zhang

J.H. Zheng

S.Y. Xu

Z. Zhao

L.C. Sun

F. Guan

X.L. Wu

W.X. Huang

Y.L. Tian

Y.S. Wang

J.Y. Wang

Z.W. Lu

Y. He

L.T. Sun

Z.Z. Ren

S.G. Zhou

Russia

V.K. Utyonkov

A.A. Voinov

Yu. S. Tsyganov

A.N. Polyakov

Corrigendum to “Decay properties of new isotopes 235Bk and 231Am” [Physics Letters B 875 (2026) 140365]

We investigate the $\textit{b}$ → $\textit{c}$ semileptonic sum rule in the presence of a massive sterile neutrino. Recent measurements of charged-current semitauonic $\textit{B}$-meson decays exhibit a ∼ 4$\textit{σ}$ deviation from the Standard Model predictions, whereas no such tension has been reported for the lowest-lying baryonic counterpart, the Λ decay. Since these decay rates are related through the sum rule, accommodating such a mismatch beyond the level of uncertainties is nontrivial. We revisit this issue by considering dimension-six operators involving a massive sterile neutrino, and evaluate the resulting violation of the sum rule. We find that the induced effect remains negligible compared with the current experimental uncertainties, further strengthening the sum rule as a consistency check for the experimental data.

Motoi Endo

Syuhei Iguro

Tim Kretz

Satoshi Mishima

$\textit{b}$ → $\textit{c}$ semileptonic sum rule: exploring a sterile neutrino loophole

We study the rates of two-body charmed-anticharmed baryonic <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mover accent="true"><mrow><mi>B</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover><mo stretchy="false">→</mo><msub><mrow><mi mathvariant="script">B</mi></mrow><mrow><mi>c</mi></mrow></msub><msub><mrow><mover accent="true"><mrow><mi mathvariant="script">B</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover></mrow><mrow><mi>c</mi></mrow></msub></mrow></math> decays using the topological amplitude approach. All amplitudes of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>B</mi><mo stretchy="false">¯</mo></mover><mo stretchy="false">→</mo><msub><mi mathvariant="script">B</mi><mi>c</mi></msub><mo stretchy="false">(</mo><msub><mover accent="true"><mn mathvariant="bold">3</mn><mo stretchy="false">¯</mo></mover><mi mathvariant="bold">f</mi></msub><mo stretchy="false">)</mo><msub><mover accent="true"><mi mathvariant="script">B</mi><mo stretchy="false">¯</mo></mover><mi>c</mi></msub><mo stretchy="false">(</mo><msub><mn mathvariant="bold">3</mn><mi mathvariant="bold">f</mi></msub><mo stretchy="false">)</mo></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="script">B</mi><mi>c</mi></msub><mo stretchy="false">(</mo><msub><mn mathvariant="bold">6</mn><mi mathvariant="bold">f</mi></msub><mo stretchy="false">)</mo><msub><mover accent="true"><mi mathvariant="script">B</mi><mo stretchy="false">¯</mo></mover><mi>c</mi></msub><mo stretchy="false">(</mo><msub><mn mathvariant="bold">3</mn><mi mathvariant="bold">f</mi></msub><mo stretchy="false">)</mo></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="script">B</mi><mi>c</mi></msub><mo stretchy="false">(</mo><msub><mover accent="true"><mn mathvariant="bold">3</mn><mo stretchy="false">¯</mo></mover><mi mathvariant="bold">f</mi></msub><mo stretchy="false">)</mo><msub><mover accent="true"><mi mathvariant="script">B</mi><mo stretchy="false">¯</mo></mover><mi>c</mi></msub><mo stretchy="false">(</mo><msub><mover accent="true"><mn mathvariant="bold">6</mn><mo stretchy="false">¯</mo></mover><mi mathvariant="bold">f</mi></msub><mo stretchy="false">)</mo></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="script">B</mi><mi>c</mi></msub><mo stretchy="false">(</mo><msub><mn mathvariant="bold">6</mn><mi mathvariant="bold">f</mi></msub><mo stretchy="false">)</mo><msub><mover accent="true"><mi mathvariant="script">B</mi><mo stretchy="false">¯</mo></mover><mi>c</mi></msub><mo stretchy="false">(</mo><msub><mover accent="true"><mn mathvariant="bold">6</mn><mo stretchy="false">¯</mo></mover><mi mathvariant="bold">f</mi></msub><mo stretchy="false">)</mo></math> decays are decomposed topologically. SU(3) breaking effects on these amplitudes, depending on the position of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>s</mi></math>-quark line, are modeled. Using existing data as input, we obtained the following results: (i) In the low-lying <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>B</mi><mo stretchy="false">¯</mo></mover><mo stretchy="false">→</mo><msub><mi mathvariant="script">B</mi><mi>c</mi></msub><mo stretchy="false">(</mo><msub><mover accent="true"><mn mathvariant="bold">3</mn><mo stretchy="false">¯</mo></mover><mi mathvariant="bold">f</mi></msub><mo stretchy="false">)</mo><msub><mover accent="true"><mi mathvariant="script">B</mi><mo stretchy="false">¯</mo></mover><mi>c</mi></msub><mo stretchy="false">(</mo><msub><mn mathvariant="bold">3</mn><mi mathvariant="bold">f</mi></msub><mo stretchy="false">)</mo></math> decays, we find that the exchange diagram is sizable. Furthermore, there is a large cancellation between internal <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>W</mi></math>-tree and exchange-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>W</mi></math>-tree amplitudes. The SU(3) breaking is sizable, 35% SU(3) breaking effects are needed, and they work differently in different amplitudes. Namely, the internal <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>W</mi></math>-tree amplitude is enlarged, while the exchange-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>W</mi></math>-tree amplitude is reduced. The rates of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>B</mi><mo stretchy="false">¯</mo></mover><mo stretchy="false">→</mo><msub><mi mathvariant="script">B</mi><mi>c</mi></msub><mo stretchy="false">(</mo><msub><mover accent="true"><mn mathvariant="bold">3</mn><mo stretchy="false">¯</mo></mover><mi mathvariant="bold">f</mi></msub><mo stretchy="false">)</mo><msub><mover accent="true"><mi mathvariant="script">B</mi><mo stretchy="false">¯</mo></mover><mi>c</mi></msub><mo stretchy="false">(</mo><msub><mn mathvariant="bold">3</mn><mi mathvariant="bold">f</mi></msub><mo stretchy="false">)</mo></math> decays with excited <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="script">B</mi><mi>c</mi></msub><mo stretchy="false">(</mo><msub><mover accent="true"><mn mathvariant="bold">3</mn><mo stretchy="false">¯</mo></mover><mi mathvariant="bold">f</mi></msub><mo stretchy="false">)</mo></math>, such as <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Λ</mi><mi>c</mi></msub><mo stretchy="false">(</mo><mn>2595</mn><msup><mo stretchy="false">)</mo><mo>+</mo></msup></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Ξ</mi><mi>c</mi></msub><mo stretchy="false">(</mo><mn>2790</mn><msup><mo stretchy="false">)</mo><mrow><mo>+</mo><mo>,</mo><mn>0</mn></mrow></msup></math>, are also studied. (ii) The <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>B</mi><mo stretchy="false">¯</mo></mover><mo stretchy="false">→</mo><msub><mi mathvariant="script">B</mi><mi>c</mi></msub><mo stretchy="false">(</mo><msub><mn mathvariant="bold">6</mn><mi mathvariant="bold">f</mi></msub><mo stretchy="false">)</mo><msub><mover accent="true"><mi mathvariant="script">B</mi><mo stretchy="false">¯</mo></mover><mi>c</mi></msub><mo stretchy="false">(</mo><msub><mn mathvariant="bold">3</mn><mi mathvariant="bold">f</mi></msub><mo stretchy="false">)</mo></math> decays, with low-lying <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mover accent="true"><mi mathvariant="script">B</mi><mo stretchy="false">¯</mo></mover><mi>c</mi></msub><mo stretchy="false">(</mo><msub><mn mathvariant="bold">3</mn><mi mathvariant="bold">f</mi></msub><mo stretchy="false">)</mo></math> and low-lying and excited <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="script">B</mi><mi>c</mi></msub><mo stretchy="false">(</mo><msub><mn mathvariant="bold">6</mn><mi mathvariant="bold">f</mi></msub><mo stretchy="false">)</mo></math> baryons, such as <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Σ</mi><mi>c</mi></msub><mo stretchy="false">(</mo><mn>2520</mn><msup><mo stretchy="false">)</mo><mrow><mo>+</mo><mo>,</mo><mn>0</mn></mrow></msup></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Ξ</mi><mi>c</mi></msub><mo stretchy="false">(</mo><mn>2645</mn><msup><mo stretchy="false">)</mo><mrow><mo>+</mo><mo>,</mo><mn>0</mn></mrow></msup></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Ω</mi><mi>c</mi></msub><mo stretchy="false">(</mo><mn>2770</mn><msup><mo stretchy="false">)</mo><mn>0</mn></msup></math>, are studied with some predictions on rates obtained. Furthermore, as the excited states are spin-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>3</mn><mo>/</mo><mn>2</mn></mrow></math> states, some of their rates are highly suppressed by the kinematic factor. (iii) The <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>B</mi><mo stretchy="false">¯</mo></mover><mo stretchy="false">→</mo><msub><mi mathvariant="script">B</mi><mi>c</mi></msub><mo stretchy="false">(</mo><msub><mover accent="true"><mn mathvariant="bold">3</mn><mo stretchy="false">¯</mo></mover><mi mathvariant="bold">f</mi></msub><mo stretchy="false">)</mo><msub><mover accent="true"><mi mathvariant="script">B</mi><mo stretchy="false">¯</mo></mover><mi>c</mi></msub><mo stretchy="false">(</mo><msub><mover accent="true"><mn mathvariant="bold">6</mn><mo stretchy="false">¯</mo></mover><mi mathvariant="bold">f</mi></msub><mo stretchy="false">)</mo></math> decays with low-lying charmed-anticharmed baryons are studied with some predictions on rates obtained. (iv) Uncertainties in most predicted rates are large, reflecting our current poor understanding of the related SU(3) breaking effects. Measuring these rates can provide very useful information about these effects.

Chun-Khiang Chua

Two-body charmed-anticharmed baryonic <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi></math> decays

Spain

Arnau Bas i Beneito

Slovenia

Svjetlana Fajfer

United States

Alexey Petrov

Erratum: New avenues for $\textit{|}$∆$\textit{B|}$ = 2 processes beyond neutron-antineutron oscillations

We calculate inclusive $\textit{B}$-meson decay rates in the Mesogenesis framework — a model explaining baryogenesis and the existence of dark matter — using the Heavy Quark Expansion (HQE), up to the dimension-six two-quark Darwin term. By systematically studying the power-suppressed contributions, we identify regions of parameter space where subleading terms exceed the leading contribution, i.e., the free $\textit{b}$-quark decay, highlighting the limits of the HQE in this BSM scenario. This behavior is reminiscent of the Standard Model only under artificially heavy charm masses, and can be used to study the HQE close to its breakdown. We further update the lower bounds on the exclusive decay mode $\textit{B}$ → $\textit{p}$ $\textit{ψ}$ by incorporating the fully HQE-corrected inclusive width in the ratio Γ $\textit{/}$Γ . Extending the analysis from total decay rates to the lifetime ratio $\textit{τ}$($\textit{B}$ )$\textit{/τ}$($\textit{B}$ ), we find no additional constraints on the couplings beyond existing collider bounds, consistent with analogous results for $\textit{τ}$($\textit{B}$ )$\textit{/τ}$($\textit{B}$ ). We further compare the sensitivity of both lifetime ratios.

Ali Mohamed

Are subleading effects really subleading? $\textit{B}$-meson decays in mesogenesis

We report a measurement of the branching fraction for the leptonic decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mo>+</mo></msup><mo stretchy="false">→</mo><msup><mi>μ</mi><mo>+</mo></msup><msub><mi>ν</mi><mi>μ</mi></msub></math>. This work presents the first <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mo>+</mo></msup><mo stretchy="false">→</mo><msup><mi>μ</mi><mo>+</mo></msup><msub><mi>ν</mi><mi>μ</mi></msub></math> result using Belle II data, an updated Belle measurement that supersedes the previous result, and their combination, which yields the most precise search to date. The analysis is based on <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1076</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math> of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> collision data collected at a center-of-mass energy of 10.58 GeV with the Belle and Belle II detectors at the KEKB and SuperKEKB colliders, respectively. We measure <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><msup><mi>B</mi><mo>+</mo></msup><mo stretchy="false">→</mo><msup><mi>μ</mi><mo>+</mo></msup><msub><mi>ν</mi><mi>μ</mi></msub><mo stretchy="false">)</mo><mo>=</mo><mspace linebreak="goodbreak"></mspace><mo stretchy="false">(</mo><mn>4.4</mn><mo>±</mo><mn>1.9</mn><mo>±</mo><mn>1.0</mn><mo stretchy="false">)</mo><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>7</mn></mrow></msup></math>, where the first uncertainty is statistical and the second systematic. The observed significance relative to the background-only hypothesis is 2.4 standard deviations. We set a 90% confidence level upper limit of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><msup><mi>B</mi><mo>+</mo></msup><mo stretchy="false">→</mo><msup><mi>μ</mi><mo>+</mo></msup><msub><mi>ν</mi><mi>μ</mi></msub><mo stretchy="false">)</mo><mo>&lt;</mo><mn>6.7</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>7</mn></mrow></msup></math> using a frequentist approach and a 90% credibility level upper limit of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><msup><mi>B</mi><mo>+</mo></msup><mo stretchy="false">→</mo><msup><mi>μ</mi><mo>+</mo></msup><msub><mi>ν</mi><mi>μ</mi></msub><mo stretchy="false">)</mo><mo>&lt;</mo><mn>7.2</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>7</mn></mrow></msup></math> using a Bayesian approach. These are the most stringent limits to date. The result is interpreted as an exclusion region in the parameter space of type II and type III two-Higgs-doublet models. We search for stable sterile neutrinos with masses <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>N</mi></msub><mo>∈</mo><mo stretchy="false">[</mo><mn>0</mn><mo>,</mo><mn>1.5</mn><mo stretchy="false">]</mo><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>. No signal is observed, and the resulting exclusion on the squared mixing parameter <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">|</mo><msub><mi>U</mi><mrow><mi>μ</mi><mi>N</mi></mrow></msub><msup><mo stretchy="false">|</mo><mn>2</mn></msup></math> provides improvement over previous limits. We report a measurement of the partial branching fraction of semileptonic <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><msub><mi>X</mi><mi>u</mi></msub><mo>ℓ</mo><msub><mi>ν</mi><mo>ℓ</mo></msub></math> decays with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>p</mi><mi>μ</mi><mi>B</mi></msubsup><mo>&gt;</mo><mn>2.2</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>, obtaining <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Δ</mi><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><mi>B</mi><mo stretchy="false">→</mo><msub><mi>X</mi><mi>u</mi></msub><mo>ℓ</mo><msub><mi>ν</mi><mo>ℓ</mo></msub><mo stretchy="false">)</mo><mo>=</mo><mo stretchy="false">(</mo><mn>2.72</mn><mo>±</mo><mn>0.05</mn><mo>±</mo><mn>0.29</mn><mo stretchy="false">)</mo><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>4</mn></mrow></msup></math>. We present a model-dependent study of weak annihilation decays using the muon momentum spectrum. We observe a signal of 2.4 standard deviations above the background-only hypothesis in regions where the distribution resembles that of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><msub><mi>X</mi><mi>u</mi></msub><mo>ℓ</mo><msub><mi>ν</mi><mo>ℓ</mo></msub></math> decays.

M. Abumusabh

I. Adachi

K. Adamczyk

A. Aggarwal

L. Aggarwal

H. Ahmed

Y. Ahn

H. Aihara

N. Akopov

S. Alghamdi

M. Alhakami

A. Aloisio

N. Althubiti

K. Amos

N. Anh Ky

C. Antonioli

D.M. Asner

H. Atmacan

T. Aushev

R. Ayad

V. Babu

H. Bae

N.K. Baghel

S. Bahinipati

P. Bambade

Sw. Banerjee

M. Barrett

M. Bartl

J. Baudot

A. Beaubien

F. Becherer

J. Becker

J.V. Bennett

F.U. Bernlochner

V. Bertacchi

M. Bertemes

E. Bertholet

M. Bessner

S. Bettarini

F. Bianchi

T. Bilka

D. Biswas

A. Bobrov

D. Bodrov

A. Bondar

G. Bonvicini

J. Borah

A. Boschetti

A. Bozek

M. Bračko

P. Branchini

R.A. Briere

T.E. Browder

A. Budano

S. Bussino

Q. Campagna

M. Campajola

L. Cao

G. Casarosa

C. Cecchi

P. Chang

P. Cheema

L. Chen

B.G. Cheon

C. Cheshta

H. Chetri

K. Chilikin

K. Chirapatpimol

H.E. Cho

K. Cho

S.J. Cho

S.K. Choi

S. Choudhury

S. Chutia

J. Cochran

J.A. Colorado-Caicedo

I. Consigny

L. Corona

J.X. Cui

E. De La Cruz-Burelo

S.A. De La Motte

G. de Marino

G. De Nardo

G. De Pietro

R. de Sangro

M. Destefanis

S. Dey

R. Dhayal

A. Di Canto

J. Dingfelder

Z. Doležal

I. Domínguez Jiménez

T.V. Dong

X. Dong

M. Dorigo

G. Dujany

P. Ecker

D. Epifanov

J. Eppelt

R. Farkas

Study of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mo>+</mo></msup><mo stretchy="false">→</mo><msup><mi>μ</mi><mo>+</mo></msup><msub><mi>ν</mi><mi>μ</mi></msub></math> decays at Belle and Belle II

We present the first lattice QCD determination of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Ξ</mi><mi>b</mi></msub><mo stretchy="false">→</mo><mi mathvariant="normal">Ξ</mi></math> vector, axial-vector, and tensor form factors, which are relevant for the theory of rare decays including <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi mathvariant="normal">Ξ</mi></mrow><mrow><mi>b</mi></mrow></msub><mo stretchy="false">→</mo><mi mathvariant="normal">Ξ</mi><msup><mrow><mo>ℓ</mo></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mo>ℓ</mo></mrow><mrow><mo>−</mo></mrow></msup></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Ξ</mi><mi>b</mi></msub><mo stretchy="false">→</mo><mi mathvariant="normal">Ξ</mi><mi>γ</mi></math>. The calculation is performed with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>2</mn><mo>+</mo><mn>1</mn></mrow></math> flavors of domain-wall fermions at three different lattice spacings and pion masses in the range from approximately 430 to 230 MeV. The bottom quark is implemented using an anisotropic clover action. Three-point functions with a wide range of source-sink separations and model averaging are used to extract the ground-state contributions. We fit the dependence of the form factors on the momentum transfer, the pion mass, and the lattice spacing using modified <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>z</mi></math> expansions that account for subthreshold branch cuts, and apply dispersive bounds and asymptotic behavior constraints to achieve controlled uncertainties in the full semileptonic kinematic region. Using our form factor results, we present standard model predictions for the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msubsup><mrow><mi mathvariant="normal">Ξ</mi></mrow><mrow><mi>b</mi></mrow><mrow><mo>−</mo></mrow></msubsup><mo stretchy="false">→</mo><msup><mrow><mi mathvariant="normal">Ξ</mi></mrow><mrow><mo>−</mo></mrow></msup><mi>γ</mi></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msubsup><mrow><mi mathvariant="normal">Ξ</mi></mrow><mrow><mi>b</mi></mrow><mrow><mo>−</mo></mrow></msubsup><mo stretchy="false">→</mo><msup><mrow><mi mathvariant="normal">Ξ</mi></mrow><mrow><mo>−</mo></mrow></msup><msup><mrow><mi>μ</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>μ</mi></mrow><mrow><mo>−</mo></mrow></msup></mrow></math> branching fractions and two angular observables.

Callum Farrell

Stefan Meinel

<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi mathvariant="normal">Ξ</mi></mrow><mrow><mi>b</mi></mrow></msub><mo stretchy="false">→</mo><mi mathvariant="normal">Ξ</mi></mrow></math> form factors from lattice QCD and standard-model predictions for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi mathvariant="normal">Ξ</mi></mrow><mrow><mi>b</mi></mrow></msub><mo stretchy="false">→</mo><mi mathvariant="normal">Ξ</mi><msup><mrow><mi>μ</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>μ</mi></mrow><mrow><mo>−</mo></mrow></msup></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi mathvariant="normal">Ξ</mi></mrow><mrow><mi>b</mi></mrow></msub><mo stretchy="false">→</mo><mi mathvariant="normal">Ξ</mi><mi>γ</mi></mrow></math> decays

We present an effective field theory (EFT) framework for coupled-channel <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msup><msup><mover accent="true"><mi>D</mi><mo stretchy="false">¯</mo></mover><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msup></math> scattering, applying it to recent lattice QCD results by Alexandrou et al. [<a href="http://dx.doi.org/10.1103/PhysRevLett.132.151902">Phys. Rev. Lett. 132, 151902 (2024)</a>]. Two complementary EFT approaches are developed: (1) a low-energy theory near the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mover accent="true"><mi>D</mi><mo stretchy="false">¯</mo></mover></math> (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>=</mo><mn>0</mn></math>) and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mo>*</mo></msup><mover accent="true"><mi>D</mi><mo stretchy="false">¯</mo></mover></math> (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>=</mo><mn>1</mn></math>) thresholds, where coupled-channel effects are integrated out; (2) coupled-channel formulation, where all relevant momentum scales are treated as soft, incorporating contact interactions and one-pion exchange (OPE). Importantly, OPE contributes to the lowest channels only through off-diagonal transitions, thus resulting in the appearance of the left-hand cut from two-pion exchange. The two approaches yield mutually consistent results, supporting the existence of shallow bound states in both channels, in agreement with the lattice findings. The finite-volume spectra and extracted pole positions show a near-degeneracy in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>=</mo><mn>0</mn></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>=</mo><mn>1</mn></math> channels, consistent with heavy-quark spin symmetry (HQSS). Using HQSS, we predict additional shallow bound states near the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><msup><mover accent="true"><mi>D</mi><mo stretchy="false">¯</mo></mover><mo>*</mo></msup></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mo>*</mo></msup><msup><mover accent="true"><mi>D</mi><mo stretchy="false">¯</mo></mover><mo>*</mo></msup></math> thresholds, which are accessible to future lattice simulations. The effect of OPE on the finite volume spectra is found to be small, with only moderate impact on HQSS partners.

Michael Abolnikov

Lu Meng

Vadim Baru

Evgeny Epelbaum

Arseniy A. Filin

Ashot M. Gasparyan

Shallow <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mrow><mi>b</mi><mi>c</mi></mrow></msub></math> states from an EFT analysis of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msup><msup><mover accent="true"><mi>D</mi><mo stretchy="false">¯</mo></mover><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msup></math> scattering on the lattice