We present the results of a search for the charged-lepton-flavor violating decays $\textit{B}$ → $\textit{K}$ $\textit{τ}$ $\textit{ℓ}$ , where $\textit{ℓ}$ is either an electron or a muon. The results are based on 365 fb and 711 fb datasets collected with the Belle II and Belle detectors, respectively. We use an exclusive hadronic $\textit{B}$-tagging technique, and search for a signal decay in the system recoiling against a fully reconstructed $\textit{B}$ meson. We find no evidence for $\textit{B}$ → $\textit{K}$ $\textit{τ}$ $\textit{ℓ}$ decays and set upper limits on the branching fractions in the range of (2.9–6.4)×10 at 90% confidence level.

I. Adachi

Y. Ahn

H. Aihara

N. Akopov

S. Alghamdi

M. Alhakami

A. Aloisio

K. Amos

M. Angelsmark

N. Anh Ky

C. Antonioli

D. Asner

H. Atmacan

V. Aushev

M. Aversano

R. Ayad

V. Babu

H. Bae

N. Baghel

S. Bahinipati

P. Bambade

Sw. Banerjee

S. Bansal

M. Barrett

J. Baudot

A. Baur

A. Beaubien

F. Becherer

J. Becker

J. Bennett

F. Bernlochner

V. Bertacchi

M. Bertemes

E. Bertholet

M. Bessner

S. Bettarini

B. Bhuyan

F. Bianchi

T. Bilka

D. Biswas

A. Bobrov

D. Bodrov

J. Borah

A. Boschetti

A. Bozek

M. Bračko

P. Branchini

R. Briere

T. Browder

A. Budano

S. Bussino

M. Campajola

L. Cao

G. Casarosa

C. Cecchi

M.C. Chang

P. Cheema

B. Cheon

K. Chilikin

J. Chin

H.E. Cho

K. Cho

S.J. Cho

S.K. Choi

S. Choudhury

I. Consigny

L. Corona

J. Cui

E. De La Cruz-Burelo

S. De La Motte

G. Marino

G. Pietro

R. Sangro

M. Destefanis

A. Canto

J. Dingfelder

Z. Doležal

I. Domínguez Jiménez

T. Dong

X. Dong

M. Dorigo

G. Dujany

P. Ecker

D. Epifanov

R. Farkas

P. Feichtinger

T. Ferber

T. Fillinger

C. Finck

G. Finocchiaro

F. Forti

A. Frey

B. Fulsom

A. Gale

E. Ganiev

M. Garcia-Hernandez

R. Garg

G. Gaudino

V. Gaur

V. Gautam

Search for lepton flavor-violating decay modes $\textit{B}$

This paper presents a novel tagging technique to measure the beauty-quark partial decay-width ratio $$R_b$$ and its forward–backward asymmetry $$A_{\textrm{FB}}^b$$ at the FCC-ee, using $$\mathcal {O}(10^{12})$$ $\textit{Z}$-boson decays. The method is based on the exclusive reconstruction of a selected list of $\textit{b}$-hadron decay modes in $$Z\rightarrow b\bar{b}$$ events at the $\textit{Z}$ pole, which can provide the flavour and possibly the charge of the hemisphere. This approach effectively eliminates the contamination from light-quark physics events and reduces the leading systematic uncertainties arising from background contamination, tagging-efficiency correlations, and gluon-radiation corrections by exploiting the geometric and kinematic properties of beauty hadrons. This results in a total relative uncertainty of the order of 0.01 % for both observables. Furthermore, this precision allows to obtain a commensurate precision on the weak mixing angle $$\sin ^2(\theta _\text {W}^{\text {eff}})$$ compared to the muon forward–backward asymmetry on the order of 0.002 %.

Germany

France

Lars Röhrig

Kevin Kröninger

Romain Madar

Stéphane Monteil

Italy

Fabrizio Palla

Switzerland

Emmanuel Perez

Measuring $$A_\textrm{FB}^b$$ and $$R_b$$ with exclusive $\textit{b}$-hadron decays at the FCC-ee

The $\textit{B}$-Mesogenesis model explains the matter-antimatter asymmetry and leads to the right amount of dark matter in the Universe. In particular, this model predicts new decay channels of the $\textit{b}$ quark. We investigate the modification of inclusive $\textit{b}$-hadron decay rates and of the lifetimes of different $\textit{B}$ mesons due to these new decay channels and compare our results with available predictions for exclusive $\textit{B}$ meson decays. We find that for the specific decay channel $\textit{b}$ → $\textit{duψ}$, only a small region of parameter space remains viable after applying current experimental constraints. This surviving region is highly constrained but not yet fully excluded. We further investigate the individual sensitivities and complementarity of the different constraints from inclusive branching ratios and lifetimes.

Alexander Lenz

Ali Mohamed

Zachary Wüthrich

Constraining $\textit{B}$-mesogenesis models with inclusive and exclusive decays

We present the results of our lattice QCD computation of the hadronic matrix elements relevant to the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>h</mi><mi>c</mi></msub><mo stretchy="false">→</mo><msub><mi>η</mi><mi>c</mi></msub><mi>γ</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>h</mi><mi>b</mi></msub><mo stretchy="false">→</mo><msub><mi>η</mi><mi>b</mi></msub><mi>γ</mi></math> decays by using the gauge configurations produced by the Extended Twisted Mass Collaboration with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>N</mi><mi>f</mi></msub><mo>=</mo><mn>2</mn><mo>+</mo><mn>1</mn><mo>+</mo><mn>1</mn></math> dynamical Wilson-Clover twisted mass fermions at five different lattice spacings with physical dynamical <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>u</mi></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>d</mi></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>s</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>c</mi></math> quark masses (except for the coarsest lattice for which the lightest sea quark corresponds to a pion with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>π</mi></msub><mo>≃</mo><mn>175</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi></math>). While the hadronic matrix element for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>h</mi><mi>c</mi></msub><mo stretchy="false">→</mo><msub><mi>η</mi><mi>c</mi></msub><mi>γ</mi></math> is obtained directly, the one relevant to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>h</mi><mi>b</mi></msub><mo stretchy="false">→</mo><msub><mi>η</mi><mi>b</mi></msub><mi>γ</mi></math> is reached by working with heavy quark masses <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>m</mi><mi>H</mi><mrow><mo stretchy="false">(</mo><mi>n</mi><mo stretchy="false">)</mo></mrow></msubsup><mo>=</mo><msup><mi>λ</mi><mrow><mi>n</mi><mo>−</mo><mn>1</mn></mrow></msup><msub><mi>m</mi><mi>c</mi></msub></math>, with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>λ</mi><mo>∼</mo><mn>1.24</mn></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>n</mi><mo>=</mo><mn>1</mn><mo>,</mo><mn>2</mn><mo>,</mo><mo>…</mo><mo>,</mo><mn>6</mn></math>, and then extrapolated to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>b</mi></msub></math> by several judicious Ansätze. In the continuum limit we obtain <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Γ</mi><mo stretchy="false">(</mo><msub><mi>h</mi><mi>c</mi></msub><mo stretchy="false">→</mo><msub><mi>η</mi><mi>c</mi></msub><mi>γ</mi><mo stretchy="false">)</mo><mo>=</mo><mn>0.604</mn><mo stretchy="false">(</mo><mn>24</mn><mo stretchy="false">)</mo><mtext> </mtext><mtext> </mtext><mi>MeV</mi></math>, which is by a factor of 2.3 more accurate than the previous lattice estimates, and in good agreement with the experimental measurement. In the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>b</mi></math>-quark case we obtain <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Γ</mi><mo stretchy="false">(</mo><msub><mi>h</mi><mi>b</mi></msub><mo stretchy="false">→</mo><msub><mi>η</mi><mi>b</mi></msub><mi>γ</mi><mo stretchy="false">)</mo><mo>=</mo><mn>46.0</mn><mo stretchy="false">(</mo><mn>4.8</mn><mo stretchy="false">)</mo><mtext> </mtext><mtext> </mtext><mi>keV</mi></math>.

D. Bečirević

R. Di Palma

R. Frezzotti

G. Gagliardi

V. Lubicz

F. Sanfilippo

N. Tantalo

Lattice QCD determination of the radiative decay rates <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>h</mi><mi>c</mi></msub><mo stretchy="false">→</mo><msub><mi>η</mi><mi>c</mi></msub><mi>γ</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>h</mi><mi>b</mi></msub><mo stretchy="false">→</mo><msub><mi>η</mi><mi>b</mi></msub><mi>γ</mi></math>

Inspired by the newly reported $$B\rightarrow D^*(\rightarrow D\pi )\ell \bar{\nu }_\ell $$ differential decay rates by the Belle and Belle II Collaborations, we revisit the $$V_{cb}$$ puzzle in semi-leptonic $$B\rightarrow D^*$$ decays, considering the latest lattice QCD (LQCD) simulations and light-cone sum rule (LCSR) results. We examine the commonly used Caprini–Lellouch–Neubert (CLN), Boyd–Grinstein–Lebed (BGL), and heavy quark effective theory (HQET) parameterizations. We demonstrate that these three parameterizations yield consistent results and reconfirm the $$V_{cb}$$ puzzle. Then, we use a state-of-the-art Bayesian method to estimate the impact of higher-order terms beyond the present HQET expansion on the uncertainty of $$V_{cb}.$$ We show that higher-order effects cannot eliminate the deviation between the exclusive and inclusive determinations of $$V_{cb}.$$ Finally, utilizing the best-fit results obtained in the HQET parameterization via fitting LQCD and LCSR data only as inputs, we predict the relevant observables, i.e., $$R_{D^*},$$ $$F_L^{D^*},$$ and $$P_\tau ^{D^*},$$ sensitive to new physics in the $$B\rightarrow D^*\ell \bar{\nu }_\ell $$ decays. We conclude that lepton-flavour universality violations still exist in the $$b\rightarrow c\tau \nu $$ transitions.

China

Shuang-Yi Li

Jie Xu

Rui-Xiang Shi

Li-Sheng Geng

Yi Zhang

$$V_{cb}$$ puzzle in semi-leptonic $$B\rightarrow D^*$$ decays revisited

In this work, we systematically study the interactions of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>S</mi></math>-wave <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msup><msup><mover accent="true"><mi>B</mi><mo stretchy="false">¯</mo></mover><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msup></math> systems within the framework of chiral effective field theory in heavy hadron formalism. We calculate the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msup><msup><mover accent="true"><mi>B</mi><mo stretchy="false">¯</mo></mover><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msup></math> effective potentials up to next-to-leading order, explore the bound state formations, and investigate the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msup><msup><mover accent="true"><mi>B</mi><mo stretchy="false">¯</mo></mover><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msup></math> scattering properties, such as scattering rate, scattering length, and effective range. Our results show that all <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>I</mi><mo>=</mo><mn>1</mn></math> <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msup><msup><mover accent="true"><mi>B</mi><mo stretchy="false">¯</mo></mover><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msup></math> potentials are repulsive, preventing the formation of bound states, while the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>I</mi><mo>=</mo><mn>0</mn></math> potentials are generally attractive. Specifically, we get two important observations: first, the shallow bound state is more likely to exist in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi><mover accent="true"><mi>B</mi><mo stretchy="false">¯</mo></mover><mo stretchy="false">[</mo><mi>I</mi><mo stretchy="false">(</mo><msup><mi>J</mi><mi>P</mi></msup><mo stretchy="false">)</mo><mo>=</mo><mn>0</mn><mo stretchy="false">(</mo><msup><mn>0</mn><mo>+</mo></msup><mo stretchy="false">)</mo><mo stretchy="false">]</mo></math> system than in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi><msup><mover accent="true"><mi>B</mi><mo stretchy="false">¯</mo></mover><mo>*</mo></msup><mo stretchy="false">[</mo><mi>I</mi><mo stretchy="false">(</mo><msup><mi>J</mi><mi>P</mi></msup><mo stretchy="false">)</mo><mo>=</mo><mn>0</mn><mo stretchy="false">(</mo><msup><mn>1</mn><mo>+</mo></msup><mo stretchy="false">)</mo><mo stretchy="false">]</mo></math> system; second, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mo>*</mo></msup><msup><mover accent="true"><mi>B</mi><mo stretchy="false">¯</mo></mover><mo>*</mo></msup><mo stretchy="false">[</mo><mi>I</mi><mo stretchy="false">(</mo><msup><mi>J</mi><mi>P</mi></msup><mo stretchy="false">)</mo><mo>=</mo><mn>0</mn><mo stretchy="false">(</mo><msup><mn>0</mn><mo>+</mo></msup><mo stretchy="false">)</mo><mo stretchy="false">]</mo></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mo>*</mo></msup><msup><mover accent="true"><mi>B</mi><mo stretchy="false">¯</mo></mover><mo>*</mo></msup><mo stretchy="false">[</mo><mi>I</mi><mo stretchy="false">(</mo><msup><mi>J</mi><mi>P</mi></msup><mo stretchy="false">)</mo><mo>=</mo><mn>0</mn><mo stretchy="false">(</mo><msup><mn>1</mn><mo>+</mo></msup><mo stretchy="false">)</mo><mo stretchy="false">]</mo></math> systems possess relatively large binding energies and positive scattering lengths, which suggests strong bound state formations in these channels. So, the attractions in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mo>*</mo></msup><msup><mover accent="true"><mi>B</mi><mo stretchy="false">¯</mo></mover><mo>*</mo></msup><mo stretchy="false">[</mo><mi>I</mi><mo>=</mo><mn>0</mn><mo stretchy="false">]</mo></math> systems are deeper than those in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi><msup><mover accent="true"><mi>B</mi><mo stretchy="false">¯</mo></mover><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msup><mo stretchy="false">[</mo><mi>I</mi><mo>=</mo><mn>0</mn><mo stretchy="false">]</mo></math> systems, thus we strongly recommend the future experiment to search for the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mo>*</mo></msup><msup><mover accent="true"><mi>B</mi><mo stretchy="false">¯</mo></mover><mo>*</mo></msup><mo stretchy="false">[</mo><mi>I</mi><mo>=</mo><mn>0</mn><mo stretchy="false">]</mo></math> tetraquark systems. We also investigate the coupled-channel effects on the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>J</mi><mo>=</mo><mn>0</mn><mo>,</mo><mn>1</mn></mrow></math> systems and conclude that the inclusion of the coupled channels introduces small but visible influences. In addition, we also investigate the dependencies of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi><msup><mover accent="true"><mi>B</mi><mo stretchy="false">¯</mo></mover><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msup></math> binding energies on the contact low-energy coupling constants.

Zhe Liu

Hao Xu

Xiang Liu

<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>D</mi></mrow><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msup><msup><mrow><mover accent="true"><mrow><mi>B</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover></mrow><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msup></mrow></math> dynamics in chiral effective field theory

The radiative seesaw model with gauged <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mrow><mi mathvariant="normal">U</mi><mo stretchy="false">(</mo><mn>1</mn><mo stretchy="false">)</mo></mrow><mrow><mi>B</mi><mo>−</mo><mi>L</mi></mrow></msub><mo>×</mo><msub><mi mathvariant="double-struck">Z</mi><mn>2</mn></msub></math> extension is a well-motivated scenario that gives consistent predictions of active neutrino masses and the abundance of dark matter. Majorana masses of right-handed neutrinos, the lightest of which can be identified as dark matter, are given by the spontaneous breaking of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mrow><mi mathvariant="normal">U</mi><mo stretchy="false">(</mo><mn>1</mn><mo stretchy="false">)</mo></mrow><mrow><mi>B</mi><mo>−</mo><mi>L</mi></mrow></msub></math> gauge symmetry. We revisit this model with the latest constraints from dark-matter searches, neutrino oscillations, flavor experiments, and collider experiments. We examine several benchmark scenarios and identify the valid parameter space of this model, finding that there are still allowed regions under the latest experimental constraints. We present new viable benchmark scenarios for this model, i.e., the right-handed neutrino dark-matter scenario and the scalar dark-matter scenario. We also mention the testability of these benchmark scenarios in future experiments.

Japan

Shinya Kanemura

Yushi Mura

Guohao Ying

Revisiting the model for radiative neutrino masses with dark matter in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mstyle mathvariant="normal"><mi>U</mi></mstyle><mo stretchy="false">(</mo><mn>1</mn><msub><mrow><mo stretchy="false">)</mo></mrow><mrow><mi>B</mi><mo>−</mo><mi>L</mi></mrow></msub></mrow></math> gauge theory

In this work we compute the branching fraction of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><msup><mi>D</mi><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msup><mi>τ</mi><msub><mi>ν</mi><mi>τ</mi></msub></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>B</mi><mi>s</mi></msub><mo stretchy="false">→</mo><msubsup><mi>D</mi><mi>s</mi><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msubsup><mi>τ</mi><msub><mi>ν</mi><mi>τ</mi></msub></math> within the relativistic independent quark model, emphasizing the harmonic potential model-dependent analysis of these decay channels in the precision flavor physics era. Considering the experimental observation of longitudinal <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>τ</mi></math>-polarization and fraction of longitudinal polarization at LHCb and Belle, we have also investigated these observables within our model framework which are aligning well with the standard model expectations. We perform a comprehensive analysis of the form factors across the whole accessible kinematic range of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>q</mi><mn>2</mn></msup></math>. Our results are consistent and compatible with other theoretical approaches as well as with the experimental measurements. Furthermore, we evaluated the clean ratios of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>B</mi><mi>s</mi></msub></math> to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>B</mi><mn>0</mn></msub></math> in the semimuonic mode that are in accordance with the LHCb measurements, and support the validity of the SU(3) flavor symmetry. Although the concept of new physics is facing a significant challenge at the current TeV scale, semileptonic <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi></math> decays, nevertheless, always serve as a valuable probe to study the decay dynamics.

India

Sonali Patnaik

Lopamudra Nayak

Sanjay Kumar Swain

<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><msup><mi>D</mi><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msup><mi>τ</mi><msub><mi>ν</mi><mi>τ</mi></msub></math> decay properties with the relativistic independent quark model

All charmless <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><mi>P</mi><mi>V</mi><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub></math> (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>P</mi></math> denotes the light pseudoscalar meson and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>V</mi></math> denotes the vector meson) decays have not been experimentally observed to date, but some of them might be measured in the near future. The charmless <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><mi>P</mi><mi>V</mi><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub></math> decays with the axial-vector (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>A</mi></math>) resonance states, the tensor (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>T</mi></math>) resonance states, and the excited vector (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>V</mi><mrow><mi>E</mi><mo>,</mo><mi>D</mi></mrow></msub></math>) resonance states are studied based on flavor SU(3) analysis in this work, where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>V</mi><mi>E</mi></msub></math> contains <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">{</mo><mi>ρ</mi><mo stretchy="false">(</mo><mn>1450</mn><mo stretchy="false">)</mo><mo>,</mo><msup><mi>K</mi><mo>*</mo></msup><mo stretchy="false">(</mo><mn>1410</mn><mo stretchy="false">)</mo><mo>,</mo><mi>ω</mi><mo stretchy="false">(</mo><mn>1420</mn><mo stretchy="false">)</mo><mo>,</mo><mi>ϕ</mi><mo stretchy="false">(</mo><mn>1680</mn><mo stretchy="false">)</mo><mo stretchy="false">}</mo></math> with quantum numbers <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>n</mi><mrow><mn>2</mn><mi>S</mi><mo>+</mo><mn>1</mn></mrow></msup><msub><mi>L</mi><mi>J</mi></msub><mo>=</mo><msup><mn>2</mn><mn>3</mn></msup><msub><mi>S</mi><mn>1</mn></msub></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>V</mi><mi>D</mi></msub></math> contains <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">{</mo><mi>ρ</mi><mo stretchy="false">(</mo><mn>1700</mn><mo stretchy="false">)</mo><mo>,</mo><msup><mi>K</mi><mo>*</mo></msup><mo stretchy="false">(</mo><mn>1680</mn><mo stretchy="false">)</mo><mo>,</mo><mi>ω</mi><mo stretchy="false">(</mo><mn>1650</mn><mo stretchy="false">)</mo><mo>,</mo><mi>ϕ</mi><mo stretchy="false">(</mo><mn>2170</mn><mo stretchy="false">)</mo><mo stretchy="false">}</mo></math> with quantum numbers <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>n</mi><mrow><mn>2</mn><mi>S</mi><mo>+</mo><mn>1</mn></mrow></msup><msub><mi>L</mi><mi>J</mi></msub><mo>=</mo><msup><mn>1</mn><mn>3</mn></msup><msub><mi>D</mi><mn>1</mn></msub></math>. The hadronic amplitudes of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><mi>A</mi><mo>/</mo><mi>T</mi><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub></math> decays are related by the nonperturbative parameters, and the branching ratio predictions of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><mi>A</mi><mo>/</mo><mi>T</mi><mo>/</mo><msub><mi>V</mi><mrow><mi>E</mi><mo>,</mo><mi>D</mi></mrow></msub><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub></math> are obtained, and then the branching ratios of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><mi>A</mi><mo stretchy="false">(</mo><mi>A</mi><mo stretchy="false">→</mo><mi>P</mi><mi>V</mi><mo stretchy="false">)</mo><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><mi>T</mi><mo stretchy="false">(</mo><mi>T</mi><mo stretchy="false">→</mo><mi>P</mi><mi>V</mi><mo stretchy="false">)</mo><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><msub><mi>V</mi><mi>E</mi></msub><mo stretchy="false">(</mo><msub><mi>V</mi><mi>E</mi></msub><mo stretchy="false">→</mo><mi>P</mi><mi>V</mi><mo stretchy="false">)</mo><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><msub><mi>V</mi><mi>D</mi></msub><mo stretchy="false">(</mo><msub><mi>V</mi><mi>D</mi></msub><mo stretchy="false">→</mo><mi>P</mi><mi>V</mi><mo stretchy="false">)</mo><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub></math> are obtained by the narrow width approximation or further considering the width effects. We find that most branching ratios of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><mi>A</mi><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub></math> decays and many branching ratios of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><mi>A</mi><mo stretchy="false">(</mo><mi>A</mi><mo stretchy="false">→</mo><mi>P</mi><mi>V</mi><mo stretchy="false">)</mo><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub></math> decays are on the order of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">O</mi><mo stretchy="false">(</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>4</mn></mrow></msup><mi>–</mi><msup><mn>10</mn><mrow><mo>−</mo><mn>3</mn></mrow></msup><mo stretchy="false">)</mo></math>, and all branching ratios with the tensor resonance states and the excited vector resonance states are small. Our results could be tested in the future Belle II and LHCb experiments.

Yi Qiao

Jin-Huan Sheng

Yuan-Guo Xu

Ru-Min Wang

Flavor SU(3) analysis of the charmless semileptonic <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><mi>P</mi><mi>V</mi><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub></math> decays

This work investigates the discovery potential for singly produced vectorlike quarks (VLQs) <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>T</mi></math> (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Q</mi><mo>=</mo><mo>+</mo><mn>2</mn><mo>/</mo><mn>3</mn><mi>e</mi></math>) and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Y</mi></math> (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Q</mi><mo>=</mo><mo>−</mo><mn>4</mn><mo>/</mo><mn>3</mn><mi>e</mi></math>) decaying to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>W</mi><mi>b</mi></math> at future <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>μ</mi><mi>p</mi></math> colliders with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>5.29</mn></math>, 6.48, and 9.16 TeV, analyzing both leptonic and hadronic <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>W</mi></math> decay channels through detailed detector simulations. The hadronic channel demonstrates superior sensitivity, enabling <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>5</mn><mi>σ</mi></math> discovery up to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>T</mi></msub><mo>=</mo><mn>3750</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math> (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>Y</mi></msub><mo>=</mo><mn>4100</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>) at 9.16 TeV with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>100</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math>, while exclusion limits reach <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>T</mi></msub><mo>=</mo><mn>4500</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math> (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>g</mi><mo>*</mo></msup><mo>≥</mo><mn>0.06</mn></math>) and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>Y</mi></msub><mo>=</mo><mn>4800</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math> (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>κ</mi><mi>Y</mi></msub><mo>≥</mo><mn>0.04</mn></math>)—significantly beyond LHC capabilities. At 5.29 TeV, discovery regions cover <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>g</mi><mo>*</mo></msup><mo>∈</mo><mo stretchy="false">[</mo><mn>0.15</mn><mo>,</mo><mn>0.5</mn><mo stretchy="false">]</mo></math> for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>T</mi></msub><mo>∈</mo><mo stretchy="false">[</mo><mn>1500</mn><mo>,</mo><mn>2520</mn><mo stretchy="false">]</mo><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>κ</mi><mi>Y</mi></msub><mo>∈</mo><mo stretchy="false">[</mo><mn>0.12</mn><mo>,</mo><mn>0.5</mn><mo stretchy="false">]</mo></math> for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>Y</mi></msub><mo>∈</mo><mo stretchy="false">[</mo><mn>1700</mn><mo>,</mo><mn>2700</mn><mo stretchy="false">]</mo><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>, with exclusions extending to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>T</mi></msub><mo>=</mo><mn>2750</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>Y</mi></msub><mo>=</mo><mn>3020</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>. These results, obtained within a simplified two-parameter framework (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mrow><mi>T</mi><mo>/</mo><mi>Y</mi></mrow></msub></math> and electroweak couplings <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>g</mi><mo>*</mo></msup></math>), establish <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>μ</mi><mi>p</mi></math> colliders as uniquely powerful tools for probing high-mass VLQ states, particularly in the boosted jet regime.

Jin-Zhong Han

Yao-Bei Liu

United Kingdom

Sweden

Stefano Moretti

Searching for single production of vectorlike quarks decaying into <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>W</mi><mi>b</mi></math> at a future muon-proton collider