Recent anomalies observed in $ e^+e^- $ nuclear transitions of $ ^8 {{\rm{Be}}} $ , $ ^4 {\rm{He}} $ , and $ ^{12} {\rm{C}} $ by the ATOMKI collaboration may hint at the existence of a vector boson with a mass around 17 MeV, which is referred to as X17. If it exists, this boson would affect similar processes in particle physics, including the Dalitz decays of vector mesons. Recently, the BESIII collaboration measured the Dalitz decay $ D^{*0}\to D^0e^+e^- $ for the first time and reported a $ 3.5\sigma $ excess over the theoretical prediction based on the vector meson dominance (VMD) model. This excess may be another signal of X17. In this study, we investigate the possible effects of X17 on the Dalitz decays $ D^*_{(s)}\to D_{(s)}e^+e^- $ , $ B^*_{(s)}\to B_{(s)}e^+e^- $ , and $ J/\psi\to \eta_ce^+e^- $ . The required hadronic form factors are calculated within the framework of our covariant confined quark model without relying on heavy quark effective theory or the VMD model. We present predictions for the Dalitz decay widths and the ratios $ R_{ee}(V)\equiv \Gamma(V\to Pe^+e^-)/\Gamma(V\to P\gamma) $ within the standard model and in several new physics scenarios involving modifications attributed to X17. Our results are compared with other theoretical calculations.

Vietnam

C.T. Tran

Russia

M.A. Ivanov

A.T.T. Nguyen

Probing the ATOMKI X17 vector boson using Dalitz decays $\textit{V}$ → $\textit{Pe}$ $^{+}$ $\textit{e}$ $^{−}$ * Supported by Ho Chi Minh City University of Technology and Education (T2024-65)

We consider a class of theories with a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">U</mi><mo stretchy="false">(</mo><mn>1</mn><msub><mo stretchy="false">)</mo><mi>X</mi></msub></math> gauge symmetry associated with leptonic chiral currents. The low-energy effective field theory includes a light spin-1 boson coupled to the electroweak gauge sector via a Wess-Zumino term, which ensures anomaly cancellation in the infrared. As a concrete application, we show that a light vector boson with mass <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>X</mi></msub><mo>≃</mo><mn>2.1</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>, coupled to a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>τ</mi></math>-lepton chiral current, can readily account for the recent <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>3</mn><mi>σ</mi></math> excess observed in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><msup><mi>K</mi><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msup><msub><mi>E</mi><mrow><mi>miss</mi></mrow></msub></math> at Belle II, while remaining consistent with existing constraints from <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi><mo stretchy="false">→</mo><mi>γ</mi><msub><mi>E</mi><mrow><mi>miss</mi></mrow></msub></math> and direct searches for anomalon fields responsible for anomaly cancellation in the ultraviolet. After classifying phenomenologically viable models, we explore in greater detail two concrete realizations which give rise to distinctive phenomenological signatures, potentially accessible at future experiments at the high-energy and intensity frontiers.

Italy

Luca Di Luzio

Marco Nardecchia

France

Claudio Toni

Gauged <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>τ</mi></math>-lepton chiral currents and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><msup><mi>K</mi><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msup><msub><mi>E</mi><mrow><mi>miss</mi></mrow></msub></math>

The N-B-LSSM is an extension of the minimal supersymmetric Standard Model (MSSM) with the addition of three singlet new Higgs superfields and right-handed neutrinos, whose local gauge group is $$SU(3)_C\times SU(2)_L\times U(1)_Y\times U(1)_{B-L}.$$ In the N-B-LSSM, we study lepton flavor violating decays $$l_j\rightarrow l_i\gamma ,$$ $$l_j \rightarrow 3l_i$$ and $$\mu \rightarrow e+ q\bar{q}$$ $$(j=\tau ,\mu ,~i=\mu ,e$$ and $$i\ne j).$$ Based on the current experimental limits, we carry out detailed parameter scanning and numerical calculation to analyse the effects of different sensitive parameters on lepton flavor violation (LFV) in the N-B-LSSM. The numerical results show that the non-diagonal elements involving the initial and final leptons are main sensitive parameters and LFV sources. This work is conducive to exploring new physics (NP) beyond the Standard Model (SM).

China

Rong-Zhi Sun

Shu-Min Zhao

Ming-Yue Liu

Xing-Yu Han

Song Gao

Portugal

Xing-Xing Dong

Lepton flavor violating decays $$l_j\rightarrow l_i\gamma ,$$ $$l_j \rightarrow 3l_i$$ and $$\mu \rightarrow e+ q\bar{q}$$ in the N-B-LSSM

The isospin-singlet scalar meson <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>f</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>980</mn><mo stretchy="false">)</mo></math> is hypothesized to consist of two energy eigenstates, forming a mixture of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mfrac><mn>1</mn><msqrt><mn>2</mn></msqrt></mfrac><mo stretchy="false">(</mo><mover accent="true"><mi>u</mi><mo stretchy="false">¯</mo></mover><mi>u</mi><mo>+</mo><mover accent="true"><mi>d</mi><mo stretchy="false">¯</mo></mover><mi>d</mi><mo stretchy="false">)</mo></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>s</mi><mo stretchy="false">¯</mo></mover><mi>s</mi></math>. Building on this framework, we apply the quantum chromodynamics (QCD) sum rules approach in the background field theory to compute the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>f</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>980</mn><mo stretchy="false">)</mo></math> decay constant, yielding <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>f</mi><msub><mi>f</mi><mn>0</mn></msub></msub><mo stretchy="false">(</mo><msub><mi>μ</mi><mn>0</mn></msub><mo>=</mo><mn>1</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi><mo stretchy="false">)</mo><mo>=</mo><mn>0.386</mn><mo>±</mo><mn>0.009</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>. Subsequently, we derive the first two <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ξ</mi></math>-moments of the leading-twist light-cone distribution amplitude <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>ϕ</mi><mrow><mn>2</mn><mo>;</mo><msub><mi>f</mi><mn>0</mn></msub></mrow></msub></math>. Using QCD light-cone sum rules, we then calculate the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>D</mi><mi>s</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><msub><mi>f</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>980</mn><mo stretchy="false">)</mo></math> transition form factor (TFF) <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>f</mi><mo>+</mo></msub><mo stretchy="false">(</mo><msup><mi>q</mi><mn>2</mn></msup><mo stretchy="false">)</mo></math>, obtaining <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>f</mi><mo>+</mo></msub><mo stretchy="false">(</mo><mn>0</mn><mo stretchy="false">)</mo><mo>=</mo><mn>0.51</mn><msubsup><mn>6</mn><mrow><mo>−</mo><mn>0.024</mn></mrow><mrow><mo>+</mo><mn>0.027</mn></mrow></msubsup></math> at the large-recoil region. We extend <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>f</mi><mo>+</mo></msub><mo stretchy="false">(</mo><msup><mi>q</mi><mn>2</mn></msup><mo stretchy="false">)</mo></math> to the full physical region via a simplified series expansion parametrization, enabling calculations of the differential decay widths and the branching fraction <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><msubsup><mi>D</mi><mi>s</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><msub><mi>f</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>980</mn><mo stretchy="false">)</mo><mo stretchy="false">(</mo><mo stretchy="false">→</mo><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup><mo stretchy="false">)</mo><msup><mi>e</mi><mo>+</mo></msup><msub><mi>ν</mi><mi>e</mi></msub><mo stretchy="false">)</mo><mo>=</mo><mspace linebreak="goodbreak"></mspace><mo stretchy="false">(</mo><mn>1.78</mn><msubsup><mn>3</mn><mrow><mo>−</mo><mn>0.189</mn></mrow><mrow><mo>+</mo><mn>0.227</mn></mrow></msubsup><mo stretchy="false">)</mo><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>3</mn></mrow></msup></math>. Our theoretical predictions align well with the latest BESIII Collaboration measurements within reasonable errors.

Dan-Dan Hu

Xing-Gang Wu

Hai-Jiang Tian

Tao Zhong

Hai-Bing Fu

Light-cone sum rules analysis of the semileptonic <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>D</mi><mi>s</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><msub><mi>f</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>980</mn><mo stretchy="false">)</mo><mspace linebreak="goodbreak"></mspace><mo stretchy="false">(</mo><mo stretchy="false">→</mo><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup><mo stretchy="false">)</mo><msup><mi>e</mi><mo>+</mo></msup><msub><mi>ν</mi><mi>e</mi></msub></math> decay incorporating the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>f</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>980</mn><mo stretchy="false">)</mo></math> mixing state twist-2 distribution amplitudes

While charged lepton-flavor-violating tau decays to strange mesons provide powerful probes of the underlying <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>τ</mi><mo stretchy="false">→</mo><mo>ℓ</mo><mi>d</mi><mover accent="true"><mi>s</mi><mo stretchy="false">¯</mo></mover></math> transition, the corresponding decay modes involving hyperons are kinematically forbidden. To address this gap, we propose the quasielastic scattering processes <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mo>−</mo></msup><mi>N</mi><mo stretchy="false">→</mo><msup><mi>τ</mi><mo>−</mo></msup><mi>Y</mi></math>. Within a general low-energy effective Lagrangian, we perform a comprehensive analysis of the final-state polarizations of both the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>τ</mi></math> lepton and the hyperon <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Y</mi></math>, systematically addressing the theoretical uncertainty driven by the model dependence of form factors. Our analysis demonstrates that while this uncertainty leads to large variations in predicted rates, the polarization observables can potentially distinguish between the form factor models, and help to determine the chiral nature of the vectorial new physics interaction. Finally, we forecast the event rates for future facilities, revealing a strong dependence on the form factor models, with predicted yields ranging from potentially observable levels to rates far below current detection thresholds.

Xin-Shuai Yan

Zhen-Qing Hu

Qin Chang

Ya-Dong Yang

Polarization probes of new physics in lepton-flavor-violating hyperon production from <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mo>−</mo></msup><mi>N</mi><mo stretchy="false">→</mo><msup><mi>τ</mi><mo>−</mo></msup><mi>Y</mi></math> scattering

We explore the constraints on new physics from the recent NA62 observation of the kaon decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>K</mi></mrow><mrow><mo>+</mo></mrow></msup><mo stretchy="false">→</mo><msup><mrow><mi>π</mi></mrow><mrow><mo>+</mo></mrow></msup><mo>+</mo><menclose notation="updiagonalstrike" other="updiag1"><mrow><mi>E</mi></mrow></menclose></mrow></math> with missing energy <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><menclose notation="updiagonalstrike" other="updiag1"><mrow><mi>E</mi></mrow></menclose></mrow></math> in the context of a dark-matter (DM) scenario recently used to accommodate the Belle II finding of an enhanced rate of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>b</mi></math>-meson decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>B</mi></mrow><mrow><mo>+</mo></mrow></msup><mo stretchy="false">→</mo><msup><mrow><mi>K</mi></mrow><mrow><mo>+</mo></mrow></msup><mo>+</mo><menclose notation="updiagonalstrike" other="updiag1"><mrow><mi>E</mi></mrow></menclose></mrow></math> compared to the standard-model expectation. Specifically, assuming that a light real scalar boson <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ϕ</mi></math> plays the role of DM and working in an effective field-theory framework, we study model independently the impact of operators involving <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ϕ</mi></math> and ordinary quarks on the aforementioned transitions over the kaon mode’s kinematical mass region of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>m</mi></mrow><mrow><mi>ϕ</mi></mrow></msub><mo>&lt;</mo><mo stretchy="false">(</mo><msub><mrow><mi>m</mi></mrow><mrow><mi>K</mi></mrow></msub><mo>−</mo><msub><mrow><mi>m</mi></mrow><mrow><mi>π</mi></mrow></msub><mo stretchy="false">)</mo><mo>/</mo><mn>2</mn><mo>=</mo><mn>177</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi></mrow></math>. Such a DM particle is subject to significant restrictions from the observed relic abundance and from DM direct-detection experiments incorporating the Migdal effect, as well as from indirect searches in cosmic microwave background data and collider experiments, except when its mass is between 110 and 146 MeV. We demonstrate that <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>K</mi><mo>+</mo></msup><mo stretchy="false">→</mo><msup><mi>π</mi><mo>+</mo></msup><mi>ϕ</mi><mi>ϕ</mi></math> can saturate the new-physics window in the NA62 result if <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>ϕ</mi></msub></math> lies in the 110–130 MeV portion of the range left by the DM constraints, thus providing a complementary constraint on this scenario. Improved data from future Belle II and NA62 measurements and DM quests can test it more stringently. In particular, expanding the NA62 signal window into the region that is now removed due to three-body decay background modes could further explore the remaining mass window for this type of invisible particle, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>130</mn><mo>&lt;</mo><msub><mi>m</mi><mi>ϕ</mi></msub><mo>&lt;</mo><mn>177</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi></math>.

Xiao-Gang He

Xiao-Dong Ma

Jusak Tandean

Australia

German Valencia

Light dark-matter window constrained by <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>K</mi></mrow><mrow><mo>+</mo></mrow></msup><mo stretchy="false">→</mo><msup><mrow><mi>π</mi></mrow><mrow><mo>+</mo></mrow></msup><mo>+</mo><menclose notation="updiagonalstrike" other="updiag1"><mrow><mi>E</mi></mrow></menclose></mrow></math>

We investigate the phenomenology of the charged Higgs boson at the International Linear Collider (ILC) within the framework of the type-X Two-Higgs Doublet Model, where a light charged Higgs boson, with a mass around 200 GeV or even smaller than top quark mass, is still being consistent with flavor physics data as well as with collider experimental data. In the theoretically and experimentally allowed parameter space, the <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><mo stretchy="false">→</mo><msup><mi>H</mi><mo>±</mo></msup><msup><mi>W</mi><mo>∓</mo></msup><mi>S</mi></math> (with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>S</mi><mo>=</mo><mi>H</mi></mrow></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>A</mi></mrow></math>) production processes can yield signatures with event rates larger than those from <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><mo stretchy="false">→</mo><msup><mi>H</mi><mo>+</mo></msup><msup><mi>H</mi><mo>−</mo></msup></math> and offer sensitivity to the Higgs mixing parameter <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>sin</mi><mo stretchy="false">(</mo><mi>β</mi><mo>−</mo><mi>α</mi><mo stretchy="false">)</mo></math>. We consider the bosonic <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>H</mi><mo>±</mo></msup><mo stretchy="false">→</mo><msup><mi>W</mi><mo>±</mo></msup><mi>S</mi></math> decays, where the neutral scalar <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>S</mi></math> further decays into a pair of tau leptons. We show, through a detector-level Monte Carlo analysis, that the resulting <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">[</mo><mi>τ</mi><mi>τ</mi><mo stretchy="false">]</mo><mo stretchy="false">[</mo><mi>τ</mi><mi>τ</mi><mo stretchy="false">]</mo><mi>W</mi><mi>W</mi></math> final state could be seen at the ILC with at least 500 GeV center-of-mass energy and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>500</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math> of luminosity.

Morocco

Brahim Ait Ouazghour

Taiwan

Abdesslam Arhrib

South Korea

Kingman Cheung

Es-said Ghourmin

Mohamed Krab

Larbi Rahili

Searching for charged Higgs bosons via <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><mo stretchy="false">→</mo><msup><mi>H</mi><mo>±</mo></msup><msup><mi>W</mi><mo>∓</mo></msup><mi>S</mi></math> at the ILC

Recent high-precision <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><mo stretchy="false">→</mo><mi>c</mi><mover accent="true"><mi>c</mi><mo stretchy="false">¯</mo></mover></math> data from BESIII and Belle are highly useful to understand vector charmonium (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi></math>) pole structures and puzzling line shapes due to the exotic hadron candidates <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Y</mi></math>. We, thus, perform a global coupled-channel analysis of most of the available data (ten two-body, nine three-body, and one four-body final states) in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mrow><mrow><msqrt><mrow><mi>s</mi></mrow></msqrt><mo>=</mo></mrow><mn>3.75</mn><mtext> </mtext><mo>−</mo><mn>4.7</mn></mrow><mtext> </mtext><mi>GeV</mi></mrow></math>. Not only cross sections, but also invariant-mass distributions of subsystems are fitted. The <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><mo stretchy="false">→</mo><msup><mi>μ</mi><mo>+</mo></msup><msup><mi>μ</mi><mo>−</mo></msup></math> cross sections are also predicted. Our model includes dozens of (quasi-)two-body states that nonperturbatively couple with each other through bare <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi></math> excitations, particle-exchange, and short-range mechanisms; approximate three-body unitarity is considered. The amplitudes obtained from the fit are analytically continued to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>Z</mi><mi>c</mi></msub></math> poles. We find <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi></math> states similar to those in the Particle Data Group listing and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Y</mi><mo stretchy="false">(</mo><mn>4320</mn><mo stretchy="false">)</mo></math>. Moreover, several <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi></math> states, including new ones, are found close to open-charm thresholds. Trajectories and compositeness of the near-threshold poles suggest dominant hadron-molecule contents in their internal structures. Two <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>Z</mi><mi>c</mi></msub></math> poles are found as virtual states <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>∼</mo><mn>40</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi></math> below the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mo>*</mo></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> thresholds, consistent with lattice QCD results. This work presents the first global analysis to determine <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>Z</mi><mi>c</mi></msub></math> poles, thereby paving the way to extracting detailed properties of the prominent exotic hadron candidates from data.

S.X. Nakamura

X.H. Li

H.P. Peng

Z.T. Sun

X.R. Zhou

Global coupled-channel analysis 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><mo stretchy="false">→</mo><mi>c</mi><mover accent="true"><mi>c</mi><mo stretchy="false">¯</mo></mover></math> processes in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mrow><msqrt><mrow><mi>s</mi></mrow></msqrt><mo>=</mo></mrow><mn>3.75</mn><mtext> </mtext><mi>to</mi><mtext> </mtext><mn>4.7</mn><mtext> </mtext><mi>GeV</mi></mrow></math>

The rare semi-leptonic decays $$B\rightarrow K^*\ell ^+\ell ^-$$ , with $$\ell =e, \mu $$ , are highly sensitive to new physics (NP) due to their suppression in the Standard Model (SM). Current LHCb measurements in the muon channel exhibit a significant tension with state-of-the-art SM theory predictions. The proposed tera-$\textit{Z}$ run at FCC-ee provides a unique opportunity to untangle the origin of this tension by producing a very large sample of $\textit{B}$-mesons in a clean $$e^+e^-$$ environment. We explore the expected precision of $$B\rightarrow K^*\ell ^+\ell ^-$$ ( $$\ell =e, \mu $$ ) measurements at FCC-ee, complementing existing studies with $$\tau ^+\tau ^-$$ in the final state, and compare with HL-LHC projections. For the case of muons in the final state, we show that HL-LHC and FCC-ee are expected to deliver a similar number of events, while the latter performs much better in the case of final state electrons. Regardless of the lepton flavour, we expect the FCC-ee environment to be much cleaner than at HL-LHC, with subleading systematics. We also find that a significant reduction in theory uncertainties on the SM predictions is required to capitalize on the advantage going from HL-LHC to FCC-ee. We demonstrate the power of such measurements at FCC-ee to extract information on the long-distance contribution to these decays, and to reveal evidence for new physics even if no deviations are seen in electroweak precision tests.

Switzerland

Marzia Bordone

Claudia Cornella

Joe Davighi

Precision tests in $$\varvec{b\rightarrow s\ell ^+\ell ^-}$$ ( $$\varvec{\ell =e,\mu }$$ ) at FCC-ee

The first simultaneous measurements of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>ν</mi><mi>μ</mi></msub></math> quasielasticlike cross section on C, CH, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mrow><msub><mrow><mi mathvariant="normal">H</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow><mi mathvariant="normal">O</mi></mrow></math>, Fe, and Pb targets as a function of kinematic imbalance variables in the plane transverse to the incoming neutrino direction are presented. These variables combine the muon and proton information to provide a new way to disentangle the effects of the nucleus in quasielasticlike processes. The data were obtained using a wideband <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>ν</mi><mi>μ</mi></msub></math> beam with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">⟨</mo><msub><mrow><mi mathvariant="normal">E</mi></mrow><mrow><mi>ν</mi></mrow></msub><mo stretchy="false">⟩</mo><mo>∼</mo><mn>6</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></mrow></math>. Cross-section ratios of the different target materials to CH are also shown. These measurements are used to explore the nature of the cross-section <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>A</mi></math> scaling, as well as initial and final state interaction effects. Comparisons are made to predictions from a number of commonly used neutrino Monte Carlo event generators. The range of predictions of the different models tends to cover the data but the degree and consistency of the agreement suffers in regions, and on higher <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>A</mi></math> targets, where the final state interactions are expected to be more pronounced.

United States

J. Kleykamp

India

S. Akhter

Z. Ahmad Dar

N.S. Alex

V. Ansari

Peru

M.V. Ascencio

M. Sajjad Athar

M. Betancourt

Mexico

J.L. Bonilla

A. Bravar

Brazil

G. Caceres

G.A. Díaz

H. da Motta

J. Felix

L. Fields

R. Fine

A.M. Gago

H. Gallagher

P.K. Gaur

R. Gran

E. Granados

Canada

D.A. Harris

United Kingdom

A.L. Hart

A. Klustová

M. Kordosky

D. Last

A. Lozano

X.G. Lu

S. Manly

W.A. Mann

C. Mauger

K.S. McFarland

M. Mehmood

B. Messerly

O. Moreno

J.G. Morfín

J.K. Nelson

C. Nguyen

A. Olivier

V. Paolone

G.N. Perdue

C. Pernas

K.J. Plows

M.A. Ramírez

R.D. Ransome

N. Roy

D. Ruterbories

H. Schellman

C.J. Solano Salinas

D.S. Correia

M. Sultana

V.S. Syrotenko

E. Valencia

N.H. Vaughan

A.V. Waldron

Chile

B. Yaeggy

L. Zazueta

Measurement of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>A</mi></math> dependence of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>ν</mi><mi>μ</mi></msub></math> charged-current quasielasticlike cross section as a function of muon and proton kinematics at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">⟨</mo><msub><mrow><mi>E</mi></mrow><mrow><mi>ν</mi></mrow></msub><mo stretchy="false">⟩</mo><mo>∼</mo><mn>6</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></mrow></math>