2nd Hokkaido Workshop on Particle Physics at Crossroads

Contribution List

4. The Muon Collider

Federico Meloni

03/03/2026, 09:00

Muons offer a unique opportunity to build a compact high-energy electroweak collider at the 10 TeV scale. A high-energy muon collider is
the natural next step in the exploration of fundamental physics after the HL-LHC and a natural complement to a future low-energy Higgs factory.

As an invited speaker I'd love to talk about any of these topics:
- muon collider overview
- the muon...

50. Muon Colliders: the Next Generation of Particle Accelerators

Tova Holmes

03/03/2026, 09:30

5. Neutrinos at Muon Colliders

Zhen Liu

03/03/2026, 10:00

6. MuSIC for New Physics

Hooman Davoudiasl

03/03/2026, 10:50

A Muon Synchrotron Ion Collider (MuSIC) can provide a path beyond the Electron Ion Collider at Brookhaven National Laboratory, and be part of a research and development effort towards future multi-TeV muon beams. In this talk, we illustrate that, besides being a powerful tool for studying nuclear physics and Standard Model processes, MuSIC can also have significant reach for new physics across...

7. An overview of the physics goals of the Electron-Ion Collider

Jianwei Qiu

03/03/2026, 11:20

Owing to the color confinement, phenomena of strong interaction physics could be described either in terms of fundamental quarks and gluons of Quantum Chromodynamics (QCD) or as mesons and baryons and the nuclear force between them, depending on the momentum/distance scales at which the phenomena are probed, while mesons and baryons themselves are confined dynamic systems of quarks and gluons....

8. EveNet: Toward a Universal Foundation Model for Collider Physics

Shih-Chieh Hsu

03/03/2026, 11:50

In high energy physics, most machine learning models are still built for narrow, task-specific analyses, which makes it hard to scale across the immense space of new physics possibilities. In this talk, I’ll introduce EveNet, a foundation model we developed to change that paradigm.

EveNet is a transformer trained on 500 million simulated Standard Model events, combining self-supervised...

47. TBA

Shusei Kamioka

03/03/2026, 13:20

51. TBA

Masashi OTANI

03/03/2026, 13:50

48. R&D for compact TeV accelerator

Mitsuhiro Yoshida

03/03/2026, 14:20

The development of TeV-class compact accelerators requires ultra-high electric fields, ultra-high magnetic fields, and ultra-high beam focusing technologies. Furthermore, energy recovery technology is also crucial, and the development of accelerators incorporating all these features is highly desired.
Particularly for decaying particles like muons, it is desirable to accelerate them as...

9. Disappearing Tracks and Forward Muons: Inert Triplet Dark Matter at Multi-TeV Muon Collider

Chandrima Sen

03/03/2026, 14:50

In this talk, I will discuss the prospects of probing the Inert Triplet Model (ITM) at future multi-TeV muon colliders. The ITM extends the Standard Model by a real $SU(2)_L​$ triplet scalar stabilized by a $Z_2$​ symmetry, yielding a neutral dark matter candidate accompanied by nearly mass-degenerate charged partners. Imposing theoretical consistency, collider bounds, and dark matter...

11. Testing tree level TeV scale seesaw scenarios in $\mu$TRISTAN

Arindam Das

03/03/2026, 15:25

We investigate TeV scale seesaw scenarios at $\mu^+ e^-$ and $\mu^+ \mu^+$ colliders in the $\mu$TRISTAN experiment. In minimal type-I seesaw scenario we consider two generations of Standard Model (SM) singlet heavy Majorana type Right Handed Neutrinos (RHNs) which couples with SM gauge bosons through light-heavy neutrino mixing. \bl{We discuss the prospects of probing heavy neutrinos via the...

10. Exploring Lepton Number Violation through Same-Sign Lepton Processes at Future Colliders

Towa Takahashi

03/03/2026, 15:55

We consider an extension of the Minimal Standard Model with the seesaw mechanism by two right-handed neutrinos in order to account for the neutrino mass consistent with oscillation experiments.
In particlar, we discuss the case in which they have TeV-scale masses, since it may be possible to probe them at future colliders.
A key prediction of the seesaw mechanism is that neutrinos are...

13. How Higgs is the Higgs? - A Study of Vector Boson Scattering at $\mu$TRISTAN

Risshin Okabe

03/03/2026, 16:10

Vector boson scattering (VBS) provides a direct window into the dynamics of electroweak symmetry breaking. In the Standard Model, the observed Higgs boson unitarizes the scattering of longitudinally polarized weak gauge bosons, keeping VBS cross sections under control even at high energies. If, however, the Higgs couplings deviate from their Standard Model values, the scattering amplitude...

12. Top-Yukawa coupling at muon collider

Ya-Juan Zheng

03/03/2026, 16:25

We study Top-Yukawa sensitivity of various processes at muon collider.

16. Searches for electroweak states at future plasma wakefield colliders

So Chigusa

03/03/2026, 17:00

We quantify the discovery potential of future multi-TeV plasma wakefield colliders for new electroweak multiplets. We include beam-beam effects through realistic luminosity spectra, comparing five collider configurations: e+e− and e−e− machines with round- and flat-beams, and a γγ collider. The beam-beam effects qualitatively change search strategies relative to idealized mono-energetic lepton...

49. TBA

Joshua Ruderman

03/03/2026, 17:30

25. Proton Decay and Flavor Symmetry

Satoshi Shirai

04/03/2026, 09:00

The observed hierarchies in fermion masses and mixing angles in the Standard Model, the so-called flavor puzzle, strongly suggest the presence of a new flavor structure or symmetry at high energies. At the same time, searches for nucleon decay provide one of the most powerful experimental probes of ultra-high-energy physics. Because both nucleon decay and flavor symmetries govern interactions...

29. TBA

Misao Sasaki

04/03/2026, 09:30

20. TBA

Gilad Perez

04/03/2026, 10:00

17. On the origin of lepton masses and dark matter

Hyun Min Lee

04/03/2026, 10:50

We propose the simple extensions of the Standard Model with an extra global or local abelian symmetries for the origin of masses for neutrino and charged leptons. First, we explain small neutrino masses with a Z4 symmetry by the radiative seesaw mechanism with inert doublet Higgs, right-handed neutrinos and extra singlet scalars transforming nontrivially under the Z4. In this model, we discuss...

19. Axion dark matter from heavy quarks

Mohammad Aghaie

04/03/2026, 11:20

We propose simple scenarios in which the observed dark matter abundance arises from the decays and scatterings of heavy quarks via the freeze-in production of an axion-like particle with mass in the 10 keV–1 MeV range. These models can be tested by future X-ray telescopes, and in some cases will be almost entirely probed by searches for the two-body decay K→π+invis at NA62. As a byproduct, we...

23. New Hadronic Effects in BBN and Bounds on Heavy QCD Axions

Kohsaku Tobioka

04/03/2026, 11:35

Big Bang Nucleosynthesis (BBN) is a powerful and unique probe of new particles. In particular, if hadrons are injected by a new particle during BBN, the measurement of helium-4 can constrain the lifetime of that particle to be significantly shorter than the BBN time scale. In this talk, I will discuss new developments that include previously missing effects, such as scattering processes...

26. Lepton sourced baryon asymmetry in the fourth generation model

Hsiang-nan Li

04/03/2026, 11:50

We demonstrate that the observed baryon asymmetry in the Universe can be accommodated in the extended Standard Model with sequential fourth generation fermions (SM4). We first construct the dimension-6 effective operators $(\Phi^\dagger\Phi)\bar U_L\Phi D_R$ induced by fourth-generation heavy quarks, which carry the $CP$ violation (CPV) source from the $4\times 4$ Cabibbo-Kobayashi-Maskawa...

18. Parity symmetric WIMP models

Keisuke Harigaya

04/03/2026, 13:05

We consider weakly interacting massive particle (WIMP) dark matter in a Parity solution to the strong CP problem. The WIMP phenomenology can be drastically affected by the presence of Parity partners of the WIMP and electroweak gauge bosons. We focus on a Parity extension of SU(2)L-doublet fermion dark matter, identify the viable parameter space, and derive the predictions of the theory. We...

22. SU(5) GUT with Multi Vector Multiplets

Ko Hirooka

04/03/2026, 13:35

Grand Unified Theories (GUTs) aim to unify the gauge groups of the Standard Model into a single symmetry at high energies. However, in the minimal SU(5) model, the predicted proton lifetime is significantly shorter than the current experimental lower bound, and the gauge couplings do not precisely converge at a single point. In this study, we address these issues by introducing multiple heavy...

28. TBA

Gurucharan Mohanta

05/03/2026, 09:00

24. (Tentative) A scenario of electroweak baryogenesis without EDM cancellation

Shinya Kanemura

05/03/2026, 09:30

We discuss two Higgs doublet models with successful electroweak baryogenesis but without cancellations of electric dipole moments (EDMs). For the baryogenesis, additional scalar bosons are favored to couple mainly with the top quark with CP violations. However, if they also couple to light fermions of the Standard Model, the model is limited severely by EDMs, and additional CP phases...

30. TBA

Toshifumi Noumi

05/03/2026, 10:00

31. TBA

Tom Melia

05/03/2026, 10:50

32. TBA

Stefania Gori

05/03/2026, 11:20

33. TBA

Patrick Fox

05/03/2026, 11:50

35. TBA

Abdesslam Arhrib

05/03/2026, 12:20

38. Quantum information and high energy physics

Martin White

05/03/2026, 13:35

I will summarise recent work from the Adelaide group on quantum information topics relevant to high energy physics. This includes the measurement of quantum information-inspired concepts at colliders (such as non-stabiliserness) that may give us new ways to search for BSM physics. It also includes work that suggests that some symmetries of the Standard Model and its extensions may result from...

41. TBA

Takeo Moroi

05/03/2026, 14:05

40. TBA

Sze Ching Audrey Fung

05/03/2026, 14:35

39. Real-Time Dynamics in a (2+1)-D Gauge Theory: The Stringy Nature on a Superconducting Quantum Simulator

Enrique Rico Ortega

05/03/2026, 15:25

Understanding the confinement mechanism in gauge theories and the universality of effective string-like descriptions of gauge flux tubes remains a fundamental challenge in modern physics. We probe string modes of motion with dynamical matter using a digital quantum simulation of a (2+1) dimensional gauge theory on a superconducting quantum processor with up to 144 qubits, stretching the...

46. TBA

Yuta Hamada

05/03/2026, 15:55

44. Global Aspects of Particle and Defect Physics

Sungwoo Hong

05/03/2026, 16:25

In this talk, I will introduce the notion of global aspects in the physics of particles and topological defects. A well-known example is the global structure ambiguity of the Standard Model (SM) gauge group. I will discuss the correlation between the quantization conditions of axion–gauge couplings and this global structure, and its implications on axion domain wall physics.

As another...

42. The role of the Quantum Yang Baxter Equations in particle Physics

Ivan Arraut

05/03/2026, 17:15

We analyze the connection between the Nambu-Goldstone theorem and the Quantum Yang Baxter Equations (QYBE), demonstrating in this way that the problem of counting and dispersion relation disappears when we impose constraints coming from the QYBE inside the dynamics of the Nambu-Goldstone bosons. Subsequently, we show that the the Hawking radiation is a mechanism of spontaneous symmetry...

43. Cartography of chiral-gauge theories and strong new physics

Alvaro Pastor Gutiérrez

05/03/2026, 17:30

45. Revisiting Instanton Physics

Takafumi Aoki

05/03/2026, 17:45

Instantons play a central role in the semiclassical description of non-perturbative phenomena in gauge theories. Their interpretation, however, can be subtle in the presence of spontaneous symmetry breaking or when topological information is treated in a nontrivial way.
In this talk, we revisit conceptual issues surrounding instantons, focusing on how semiclassical configurations and their...

37. Gravitational wave as signal from the early universe

Liantao Wang

06/03/2026, 09:00

34. TBA

Masahiro Ibe

06/03/2026, 09:30

15. Cosmological quasiparticles and the cosmological collider

Seung J. Lee

06/03/2026, 10:00

In this talk, I will introduce the intriguing interplay between cosmology and strongly coupled dynamics, showing how temporary spectral features can leave lasting, observable imprints on the primordial fluctuation spectrum. Focusing on nearly conformal extensions of the Standard Model and employing AdS/CFT reasoning, I will demonstrate the emergence of gapped structures and distinct...

36. TBA

Ken Van Tilburg

06/03/2026, 10:50

27. Quantum Effects on Neutrino Parameters from a Flavored Gauge Boson

Lukas Treuer

06/03/2026, 11:20

Over the past two to three decades neutrino oscillation experiments have shown that neutrinos are massive and mix significantly. This can be described largely model-independently using the dimension-five Weinberg operator, giving rise to Majorana neutrino masses after electro-weak symmetry breaking. Its renormalization and running effects have also been increasingly considered. It was found...

21. TBA

Shu-Yu HO

06/03/2026, 11:35

52. TBA

Taikan Suehara

06/03/2026, 11:50