This study investigates the ultraviolet realization of semileptonic four-fermion operator $ O_{ledq}^{\alpha \beta 11} $ that incorporates Majorana dark matter (DM) in both lepton-flavor-conserving (LFC) and lepton-flavor-violating (LFV) scenarios at the one-loop level via box diagram, thereby effectively alleviating the lower bounds on the new physics scale. In addition, we investigate the interplay between model-independent constraints on the Wilson coefficients and DM direct detection, relic density, and collider searches in the context of fermion portal DM model with two mediators. We found that both the projected future constraint on the LFC Wilson coefficient $ C_{ledq}^{2211}/\Lambda^2 \lt $ $ (12.3\; \text{TeV})^{-2} $ from the measurements of neutrino non-standard interaction in the next-generation neutrino oscillation experiments, and the LFV constraint $ C_{ledq}^{1211}/\Lambda^2 \lt \left(2.2\times 10^3\; \text{TeV} \right)^{-2} $ from ongoing charged-lepton-flavor-violation searches, provide a complementary exploration of the parameter space encompassing the DM and scalar masses. With a colored mediator mass of approximately $ 2\; \text{TeV} $ , the sensitivity of the indirect constraints on the four-fermion operator can surpass those of collider searches and DM direct detection, in scenarios where the masses of the DM and scalar are close. By ensuring the correct DM relic density, however, we find that the collider searches and DM direct detection are more sensitive to the electroweak-scale DM and scalar than indirect constraints.

China

Yuxuan He

Gang Li

Jia Liu

Xiao-Ping Wang

Xiang Zhao

Lepton flavor of four-fermion operator and fermion portal dark matter * Gang Li and Xiang Zhao are supported by the National Natural Science Foundation of China (12347105, 12505127), the Guangdong Basic and Applied Basic Research Foundation (2024A1515012668). The work of Jia Liu is supported by the National Science Foundation of China (12235001, 12475103) and State Key Laboratory of Nuclear Physics and Technology (NPT2025ZX11). The work of Xiao-Ping Wang is supported by National Science Foundation of China (12375095) and the Fundamental Research Funds for the Central Universities

This work presents a proof of concept for MUSIC, a multi-purpose detector conceived for high-precision and ultra-high-energy physics studies in the challenging environment of $$\sqrt{s}=10$$ TeV muon–antimuon collisions. The detector features a central tracking system, electromagnetic and hadronic calorimeters, and dedicated muon detectors. This paper outlines the main design elements of each subdetector, with an emphasis on the effects of machine-induced backgrounds and the reconstruction strategies employed for key physics objects. Performance results for electrons, photons, muons, and jets are reported, and studies of jet flavour identification are discussed.

Italy

Paolo Andreetto

Nazar Bartosik

Andrea Bersani

Switzerland

Daniele Calzolari

Massimo Casarsa

Vittoria Ciccarella

Elisa Meco

Ruben Gargiulo

Alessio Gianelle

Carlo Giraldin

United Kingdom

Karol Krizka

Anton Lechner

Luigi Longo

Donatella Lucchesi

Leonardo Palombini

Nadia Pastrone

Ivano Sarra

Lorenzo Sestini

Rosamaria Venditti

Davide Zuliani

Music: a multi-purpose detector concept for physics at the 10 TeV muon collider

In the Standard Model, partial unification of the non-Abelian running gauge couplings is achieved at the scale <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>μ</mi><mn>32</mn><mrow><mi>SM</mi></mrow></msubsup><mo>≈</mo><mn>2.8</mn><mo>×</mo><msup><mn>10</mn><mn>16</mn></msup><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>. Elaborating on this fact, we discuss a simple general parametrization for the new physics corrections leading to full unification at some scale <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>M</mi><mi>X</mi></msub></math>. We show that for any new physics model such that the corrections to the non-Abelian couplings are equal (or nearly so), <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>M</mi><mi>X</mi></msub></math> is equal (or close to) the partial unification scale <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>μ</mi><mn>32</mn><mrow><mi>SM</mi></mrow></msubsup></math>; the latter scales could be disentangled only if the corrections to the non-Abelian couplings are significantly different. We explore how the parametrization works for some relevant models with new physics below <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>M</mi><mi>X</mi></msub></math>, as low-energy supersymmetry, split supersymmetry, etc. As for models with a desert up to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>M</mi><mi>X</mi></msub></math>, we explore, in particular, how the parametrization works for string-inspired corrections; we find a phenomenologically remarkable possibility for unification at about 100 TeV, suggesting a low string scale, in addition to the more conservative possibility for unification at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>μ</mi><mn>32</mn><mrow><mi>SM</mi></mrow></msubsup></math>; for models with power-law running/threshold corrections, we also outline an interesting connection with the number of fermion families propagating in the bulk.

Isabella Masina

Spain

Mariano Quirós

Standard model partial unification scale as a guide to new physics model building

Extracting accurate results from neutrino oscillation and cross section experiments requires accurate simulation of the neutrino-nucleus interaction. The rescattering of outgoing hadrons (final state interactions) by the rest of the nucleus is an important component of these interactions. We present a new measurement of proton transparency (defined as the fraction of outgoing protons that emerge without significant rescattering) using electron-nucleus scattering data recorded by the CLAS detector at Jefferson Laboratory on helium, carbon, and iron targets. This analysis uses a new data-driven method to extract the transparency. It defines transparency as the ratio of electron-scattering events with a detected proton to quasi-elastic electron-scattering events where a proton should have been knocked out. Our results are consistent with previous measurements that determined the transparency from the ratio of measured events to theoretically predicted events. We find that the GENIE event generator, which is widely used by oscillation experiments to simulate neutrino-nucleus interactions, needs to better describe both the nuclear ground state and proton rescattering in order to reproduce our measured transparency ratios, especially at lower proton momenta.

United States

S. Dytman

M. Betancourt

N. Steinberg

L.B. Weinstein

Israel

A. Ashkenazi

J. Tena-Vidal

A. Papadopoulou

G. Chambers-Wall

J. Smith

P. Achenbach

France

J.S. Alvarado

M.J. Amaryan

H. Atac

Saudi Arabia

L. Baashen

N.A. Baltzell

L. Barion

M. Bashkanov

M. Battaglieri

F. Benmokhtar

A. Bianconi

A.S. Biselli

M. Bondi

F. Bossù

S. Boiarinov

Germany

K.-Th. Brinkmann

W.J. Briscoe

Chile

W.K. Brooks

S. Bueltmann

V.D. Burkert

T. Cao

R. Capobianco

D.S. Carman

J.C. Carvajal

P. Chatagnon

Russia

V. Chesnokov

H. Chinchay

G. Ciullo

P.L. Cole

M. Contalbrigo

A. D’Angelo

Armenia

N. Dashyan

R. De Vita

M. Defurne

A. Deur

S. Diehl

C. Djalali

R. Dupre

H. Egiyan

A. El Alaoui

L. El Fassi

L. Elouadrhiri

M. Farooq

S. Fegan

I.P. Fernando

A. Filippi

G. Gavalian

G.P. Gilfoyle

R.W. Gothe

L. Guo

K. Hafidi

H. Hakobyan

M. Hattawy

F. Hauenstein

T.B. Hayward

D. Heddle

A. Hobart

M. Holtrop

Yu-Chun Hung

Y. Ilieva

D.G. Ireland

E.L. Isupov

H. Jiang

South Korea

H.S. Jo

S. Joosten

M. Khandaker

A. Kim

W. Kim

F.J. Klein

V. Klimenko

A. Kripko

V. Kubarovsky

S.E. Kuhn

L. Lanza

P. Lenisa

D. Marchand

V. Mascagna

D. Matamoros

B. McKinnon

T. Mineeva

M. Mirazita

V. Mokeev

C. Munoz Camacho

P. Nadel-Turonski

T. Nagorna

K. Neupane

D. Nguyen

S. Niccolai

M. Osipenko

L.L. Pappalardo

R. Paremuzyan

Proton transparency and neutrino physics: New methods and modeling

Brazil

Níckolas Aguiar Alves

Lectures on the Bondi–Metzner–Sachs Group and related topics in infrared physics

We study the processes <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>ν</mi><mi>τ</mi></msub><mi>n</mi><mo stretchy="false">→</mo><msub><mi mathvariant="normal">Λ</mi><mi>c</mi></msub><msup><mi>τ</mi><mo>−</mo></msup><mo stretchy="false">(</mo><msup><mi>π</mi><mo>−</mo></msup><msub><mi>ν</mi><mi>τ</mi></msub><mo stretchy="false">)</mo></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mover accent="true"><mi>ν</mi><mo stretchy="false">¯</mo></mover><mi>τ</mi></msub><mi>p</mi><mo stretchy="false">→</mo><mi mathvariant="normal">Λ</mi><msup><mi>τ</mi><mo>+</mo></msup><mo stretchy="false">(</mo><msup><mi>π</mi><mo>+</mo></msup><msub><mover accent="true"><mi>ν</mi><mo stretchy="false">¯</mo></mover><mi>τ</mi></msub><mo stretchy="false">)</mo></math>, with particular emphasis on the pion energy and angular distributions, as a possible signal for lepton flavor universality violation, and in general of physics beyond the Standard Model (SM), as well as a sensitive probe of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>τ</mi></math> polarization vector. We work within an effective low-energy extension of the SM with all dimension-six four-fermion operators. In this framework, complex Wilson coefficients which encode new physics can generate <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>C</mi><mi>P</mi></mrow></math>-violating contributions. We propose an observable that provides a genuine <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>C</mi><mi>P</mi></mrow></math>-odd signal due to its sensitivity to particular transverse components of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>τ</mi></math> polarization vector. Namely, we show that the asymmetry in the azimuthal-angle distribution of the pion in the decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>τ</mi><mo>±</mo></msup><mo stretchy="false">→</mo><msup><mi>π</mi><mo>±</mo></msup><msub><mi>ν</mi><mi>τ</mi></msub></math> constitutes a smoking-gun prediction of such a beyond the SM scenario. We estimate the strength of this effect extrapolating nucleon-hyperon form factors recently obtained from lattice QCD calculations.

E. Hernández

J. Nieves

Sweden

J.E. Sobczyk

Probing new physics and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>C</mi><mi>P</mi></mrow></math> violation in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>ν</mi><mi>τ</mi></msub><mi>n</mi><mo stretchy="false">→</mo><msub><mi mathvariant="normal">Λ</mi><mi>c</mi></msub><msup><mi>τ</mi><mo>−</mo></msup><mo stretchy="false">(</mo><msup><mi>π</mi><mo>−</mo></msup><msub><mi>ν</mi><mi>τ</mi></msub><mo stretchy="false">)</mo></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mover accent="true"><mi>ν</mi><mo stretchy="false">¯</mo></mover><mi>τ</mi></msub><mi>p</mi><mo stretchy="false">→</mo><mi mathvariant="normal">Λ</mi><msup><mi>τ</mi><mo>+</mo></msup><mo stretchy="false">(</mo><msup><mi>π</mi><mo>+</mo></msup><msub><mover accent="true"><mi>ν</mi><mo stretchy="false">¯</mo></mover><mi>τ</mi></msub><mo stretchy="false">)</mo></math>

Testing new-physics (NP) scenarios that couple predominantly to the third generation is notoriously difficult experimentally, as exemplified by comparing limits for the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>τ</mi></math> lepton dipole moments to those of electrons and muons. In this case, extracting limits from processes such as <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>τ</mi><mo>+</mo></msup><msup><mi>τ</mi><mo>−</mo></msup></math> often relies on effective-field-theory (EFT) arguments, which allow for model-independent statements, but only apply if the NP scale is sufficiently large compared to the center-of-mass energy. In this work we offer a comprehensive analysis of light NP contributions to the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>τ</mi></math> dipole moments, providing a detailed account of the interpretation of asymmetry measurements in <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>τ</mi><mo>+</mo></msup><msup><mi>τ</mi><mo>−</mo></msup></math> that are tailored toward the extraction of dipole moments, for the test cases of new light spin-0 and spin-1 bosons. Moreover, we study the decoupling to the EFT limit in these scenarios and discuss the complementarity to constraints from other related processes, such as production in <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> reactions. While covering a wide range of light NP scenarios, as specific case study we present a detailed discussion of a tauphilic gauge vector boson at Belle II.

Martin Hoferichter

Gabriele Levati

Light new physics and the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>τ</mi></math> lepton dipole moments

While electron and muon dipole moments are well-established precision probes of physics beyond the standard model, it is notoriously challenging to test realistic new physics (NP) scenarios for the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>τ</mi></math> lepton. Constructing suitable asymmetries in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup><mo stretchy="false">→</mo><msup><mrow><mi>τ</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>τ</mi></mrow><mrow><mo>−</mo></mrow></msup></mrow></math> has emerged as a promising such avenue, providing access to the electric and magnetic dipole moment once a polarized electron beam is available, e.g., with the proposed polarization upgrade of the SuperKEKB <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> collider. However, this interpretation relies on an effective-field-theory (EFT) argument that only applies if the NP scale is large compared to the center-of-mass energy. In this Letter, we address the consequences of the asymmetry measurements in the case of light NP, using light spin-0 and spin-1 bosons as test cases, to show how results can again be interpreted as constraints on dipole moments, albeit in a model-dependent manner, and how the decoupling to the EFT limit proceeds in these cases. In particular, we observe that the imaginary parts generated by light new particles can yield nonvanishing asymmetries even without electron polarization, which can again be interpreted as constraints on the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>τ</mi></math> anomalous magnetic moment. This proposed measurement, thus, presents a novel opportunity for NP searches that can be realized already with present data at Belle II.

Light New Physics and the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>τ</mi></math> Lepton Dipole Moments: Prospects at Belle II

We employ an approximate conserved quantum number [defined as “<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>b</mi></math> parity” in <a href="http://dx.doi.org/10.1103/PhysRevLett.86.3722">Phys. Rev. Lett. 86, 3722 (2001)</a>] of the Standard Model (SM): <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>b</mi><mi>P</mi></msub><mo>=</mo><mo stretchy="false">(</mo><mo>−</mo><mn>1</mn><msup><mo stretchy="false">)</mo><mi>n</mi></msup></math>, where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>n</mi></math> is the number of produced <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>b</mi></math> jets in the reaction <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>e</mi><mo>+</mo><mi>p</mi><mo>/</mo><mi>A</mi><mo stretchy="false">→</mo><mi>n</mi><mo>·</mo><msub><mi>j</mi><mi>b</mi></msub><mo>+</mo><mi>X</mi></math>, to explore new TeV-scale flavor-changing interactions involving the third-generation quarks at the Electron-Ion Collider (EIC); simply by counting the number of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>b</mi></math> jets in the final state. In particular, the SM single and dijet production at the EIC, which occurs through charge current interactions, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>e</mi><mo>+</mo><mi>p</mi><mo>/</mo><mi>A</mi><mo stretchy="false">→</mo><mi>j</mi><mo>+</mo><mrow><msub><menclose notation="updiagonalstrike"><mi>E</mi></menclose><mi>T</mi></msub></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>e</mi><mo>+</mo><mi>p</mi><mo>/</mo><mi>A</mi><mo stretchy="false">→</mo><mn>2</mn><mo>·</mo><mi>j</mi><mo>+</mo><mrow><msub><menclose notation="updiagonalstrike"><mi>E</mi></menclose><mi>T</mi></msub></mrow></math>, are <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>b</mi><mi>P</mi></msub></math> even since the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>b</mi><mi>P</mi></msub></math>-violating (i.e., <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>b</mi><mi>P</mi></msub><mo>=</mo><mo>−</mo><mn>1</mn></math>) SM signals for these processes are necessarily Cabibbo-Kobayashi-Maskawa suppressed and, therefore, have a vanishingly small production rate. In contrast, new flavor physics can generate <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>b</mi><mi>P</mi></msub><mo>=</mo><mo>−</mo><mn>1</mn></math> signals at the EIC whose only significant SM background is due to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>b</mi></math>-jet misidentification. We thus show that <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>b</mi><mi>P</mi></msub></math> can be used as a simple and sensitive probe of new flavor-violating physics; specifically, we find that counting single <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>b</mi></math>-jet events in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>e</mi><mo>+</mo><mi>p</mi><mo>/</mo><mi>A</mi><mo stretchy="false">→</mo><mi>j</mi><mo>+</mo><mrow><msub><menclose notation="updiagonalstrike"><mi>E</mi></menclose><mi>T</mi></msub></mrow></math> at the EIC with a center-of-mass (c.m.) energy of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msqrt><mi>s</mi></msqrt><mo>∼</mo><mn>140</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math> can probe scales of new physics up to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="normal">Λ</mi><mo>≲</mo><mi mathvariant="script">O</mi><mo stretchy="false">(</mo><mn>5</mn><mo stretchy="false">)</mo><mtext> </mtext><mtext> </mtext><mi>TeV</mi></mrow></math> for a certain type of new chiral flavor-changing physics in third-generation interactions. This is remarkably more than 30 times larger than the assumed EIC c.m. energy and it critically depends on the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>b</mi></math>-tagging efficiency and purity as well as the feasibility of electron beam polarization. The sensitivity of the dijet process, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>e</mi><mo>+</mo><mi>p</mi><mo>/</mo><mi>A</mi><mo stretchy="false">→</mo><mn>2</mn><mi>j</mi><mo>+</mo><mrow><msub><menclose notation="updiagonalstrike"><mi>E</mi></menclose><mi>T</mi></msub></mrow></math>, to these types of new physics is reduced compared to the single-jet channel.

Shaouly Bar-Shalom

Jose Wudka

Flavor physics at the EIC with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>b</mi></mrow></math>-jet tagging

The process-independence of the color dipole amplitude is a cornerstone of high-energy Quantum Chromodynamics (QCD). However, standard phenomenological approaches typically rely on rigid parametric ansatzes and often require ad-hoc geometric adjustments to reconcile inclusive and diffractive measurements. To resolve this tension, we introduce Physics-Informed Neural Networks (PINNs) employing a “Teacher–Student” strategy. The physics-based momentum-space Balitsky-Kovchegov evolution dynamics act as the “Teacher,” constraining the solution manifold, while the network “Student” is refined against inclusive HERA <italic>F</italic> <inf>2</inf> data. This approach extracts a model-independent dipole amplitude without assuming initial states. Strikingly, we demonstrate that this amplitude&#8212;without parameter retuning or geometric rescaling&#8212;successfully predicts the absolute normalization and kinematic dependence of exclusive <italic>J</italic>/ <italic>&#968;</italic> photoproduction cross-sections. This parameter-free prediction of the saturation dynamics provides promising evidence for the process-independence of the gluon saturation scale and establishes PINNs as a transformative paradigm for uncovering non-perturbative QCD structures.

Wei Kou

Xurong Chen

Extraction of the color dipole amplitude with physics-informed neural networks