The Future is Whispering

25 Jun 2025, 09:00 → 27 Jun 2025, 18:30 Asia/Taipei

Science Building III/SC353 (NYCU)

Po-Yen Tseng (National Tsing Hua University, Department of Physics)

The Future is Whispering

“The Future is Whispering” is the fifth installment of the NCTS TG2.1 workshop series “The Future is ...”. In this edition we want to focus on feeble particle interactions which are particularly important in the early universe. Our aim is to promote young scientists and bridge gaps between various subfields within NCTS and the broader Taiwanese physics community. This year, in particular, we invite colleagues working on astroparticle physics and particle cosmology to have intense discussions on potential signals and prospects for the future of the relevant fields.

Our workshop will broadly cover the following topics:
1.     Feebly interacting particles
2.     Gravitational aspects of particle physics
3.     Dark Matter
4.     Particle physics from compact objects

For full consideration of your talk abstract, please submit it before 28 May 2025  5 June 2025 (deadline extended) and also register as a participant before 11 June 2025.

Keynote Speakers

Vedran Brdar (Oklahoma State U.)
Tom Broadhurst (DIPC)
Koichi Hamaguchi (U. of Tokyo)
Kazunori Kohri (KEK)
Kin-Wang Ng (AS)

Organizing Committee

Jan Tristram Acuña (NTHU)
Priyanka Sarmah (NTHU)
Martin Spinrath (NTHU)
Sut-Ieng Tam (NYCU)
Po-Yen Tseng (NTHU)

Sponsor

National Center for Theoretical Sciences

Hosts

National Tsing Hua University

National Yang Ming Chiao Tung University

 

Wednesday, 25 June

09:10 → 09:30 Welcome & Farewell: Welcome

Convener: Po-Yen Tseng (National Tsing Hua University, Department of Physics)

slide.pdf

09:30 → 10:30 Keynote Talks: Searching for cosmological parity violation

Convener: Jan Tristram Acuña (Department of Physics, National Tsing Hua University)

09:30 Searching for cosmological parity violation

Axions are naturally coupled to photons through the Chern-Simons term. This coupling would open a window for us to probe the dark components and the inflation by their imprints on the visible sector. Over the past years, we have explored the cosmological signatures of axionic dark energy, dark matter, and inflaton. The axionic dark energy and dark matter can rotate the plane of polarization of propagating photons, thus converting CMB E-mode polarization into parity-odd B-mode polarization (the so-called birefringence B-mode or cosmic parity violation). In axion monodromy inflation, the backreaction to inflation induced by copious photon production due to the axion-photon coupling in a later stage of inflation beyond the slow-roll regime may lead to large non-Gaussian density fluctuations that seed primordial black holes (PBHs) and simultaneously generate gravitational waves (GWs). In particular, because of the Chern-Simons axion-photon coupling, the produced photons are one-handed; as a result, the generated GWs are chiral and the four-point function of density fluctuations is parity-violating. This chirality manifests a distinct signature of the cosmic parity violation in axion cosmology. The PBHs can be a candidate for dark matter and the chirality of the GWs can be detected by on-going and future GW experiments, such as LIGO, Virgo, KAGRA, LISA, and pulsar-timing arrays. We will discuss parity violation in axion cosmology, paying attention to on-going and future measurements of the density four-point function in CMB observations and galaxy surveys.

Speaker: Prof. Kin-Wang Ng (Academia Sinica)

NYCU25_NgKW.pdf

10:30 → 11:00 Coffee Break

11:00 → 12:00 Gravitational aspects of particle physics

Convener: Jan Tristram Acuña (Department of Physics, National Tsing Hua University)

11:00 2-step FOEWPT in G2HDM

We investigate the possibility of a strong first-order electroweak phase transition (FOEWPT) during the early universe within the framework of the gauged two-Higgs doublet model (G2HDM) and explore its detectability through stochastic gravitational wave signals. The results indicate that forthcoming detectors such as BBO, LISA, DECIGO, TianQin and Taiji could potentially detect the gravitational wave signals generated by the FOEWPT. Additionally, we find that the parameter space probed by gravitational waves can also be searched for in future dark matter direct detection experiments, in particular those designed for dark matter masses in the sub-GeV range using the superfluid Helium target detectors.

Speaker: TC Yuan (IOP, Academia Sinica)

11:30 Refining Gravitational Wave and Collider Physics Dialogue via Singlet Scalar Extension

Employing effective field theory techniques, we advance computations of thermal parameters that enter predictions for the gravitational wave spectra from first-order electroweak phase transitions. Working with the real-singlet-extended Standard Model, we utilize recent lattice simulations to confirm the existence of first-order phase transitions across the free parameter space. For the first time, we account for several important two-loop corrections in the high-temperature expansion for determining thermal parameters, including the bubble wall velocity in the local thermal equilibrium approximation. We find that the requirement of completing bubble nucleation imposes stringent bounds on the new scalar boson mass. Moreover, the prospects for detection by LISA require first-order phase transitions in a two-step phase transition, which display strong sensitivity to the portal coupling between the Higgs and the singlet.
Interestingly, signals from di-Higgs boson production at the HL-LHC probe parameter regions that significantly overlap with the LISA-sensitive region, indicating the possibility of accounting for both signals if detected. Conversely, depending on the mixing angle, a null result for di-Higgs production at the HL-LHC could potentially rule out the model as an explanation for gravitational wave observations.

Speaker: Dr Van Que Tran (NCTS, National Taiwan University)

VQTran-TheFutureIs.pdf

12:00 → 13:30 Lunch Break

13:30 → 14:30 Keynote Talks: Neutron Star Eclipses as Axion Laboratories

Convener: Martin Spinrath (NTHU)

13:30 Astrophysical Probes of New Physics: From Neutron Stars to High-Energy Neutrinos

Axion-like particles (ALPs) appear in many beyond-the-Standard-Model theories, either as candidatesfor dark matter or as partners of the axion that explains the apparent conservation of charge-parity symmetry, known as the strong CP problem. In the first part of the talk, I will present a novel method for probing ALPs using eclipsing binary systems which can serve as an astrophysical realization of light-shining-through-walls experiments. Such systems are composed of a neutron star that is bright in X-rays and a larger companion star, through which ALPs produced via conversion in the neutron star's magnetosphere can pass during the eclipse. The ALPs then partially reconvert into photons in the interstellar medium on their way to Earth, and the resulting X-rays are detectable by space observatories such as XMM-Newton.

In the second part of the talk, I will focus on the recently reported KM3-230213A neutrino event reported by the KM3NeT collaboration, which is nearly an order of magnitude more energetic than the highest-energy neutrino in IceCube's catalog. Despite its larger effective area and longer data-taking period, IceCube has not observed events of similar energies, which implies a 2-3σ tension, depending on the type of neutrino source. The 220 PeV neutrino, detected at KM3NeT, traversed approximately 150 km through rock and sea, whereas neutrinos from the same location in the sky would cross only about
10 km of ice to reach IceCube. I will show how this difference in propagation distance helps to resolve this tension in the framework of a model containing a light sterile neutrino.

Speaker: Vedran Brdar (Oklahoma State University)

Vedran.pdf

14:30 → 15:00 Particle physics from compact objects

Convener: Martin Spinrath (NTHU)

14:30 Gravitational-Wave Signatures of Nonstandard Neutrino Properties in Collapsing Stellar Cores

Stellar core-collapses provide formidable conditions to probe new physics. Supernovae as one possible outcome of these events are driven by the transport of energy through neutrinos. In this talk I will present the result of numerical simulations in axial symmetry show how nonstandard neutrino interactions can lead to imprints in the gravitational wave signal of supernovae.

Speaker: Jakob EHRING (Academia Sinica, Institute of Physics)

2025-06-25-Hsinchu_TFIW-Jakob_Ehring.pdf

15:00 → 15:30 Coffee Break

15:30 → 17:00 Dark Matter

Convener: Chrisna Setyo Nugroho (National Taiwan Normal University)

15:30 Constraining Fuzzy Dark Matter Mass with Gravitationally Lensed High-z Galaxies

Ultra-light axions are well-motivated fuzzy/wave cold dark matter (CDM) candidates that provide potential resolutions to various small-scale problems faced by conventional heavy particle CDM. Being wavy on astronomical scales, galaxy formation is suppressed below the respective de Broglie wavelength scale, resulting in a sharp turnover in galaxy luminosity functions (LF) at the faint end. Such features, however, have yet to be confirmed and have only a few hints from Hubble Frontier lensing fields (e.g. Leung et al, 2018; Atek et al, 2018). Without the supplement of deep observations at longer wavelength (covering Balmer breaks of high-z galaxies), however, the high redshift sample for these lensing fields was shown to be severely contaminated, with contamination level reaching ~60% over 3.5<z<5.5 (Zhang et al, 2025). To achieve a more robust test, we here combine existing HST observations with recent deep JWST observations by the PEARLS team on field MACS J0416, and construct a photometric redshift catalog reliable up to the redshift of z~10. By measuring the surface number density of gravitationally lensed high-z galaxies behind this massive galaxy cluster, we found no evidence of faint end turnover over redshifts 6<z<10. With this, we place a constraint on the fuzzy dark matter mass to above 2.76E-22eV at 95% confidence. We will also discuss the implication of this bound if the dark matter budget is composed of multiple copies of axions, a scenario more theoretically motivated from the perspective of String Axiverse. Using linear perturbation analysis, we argue different copies of axions may resemble an equivalent copy (with mass in between the highest and lowest axion mass, depending on relative contributions to total density) in terms of suppression (i.e. where turnover occurs in UV LFs) on large-scale structure. Hence the mass constraint we obtained (likewise for the stronger constraints from Lyman alpha forest) still allows for light (e.g. 1E-22 eV) axion to dominate individual galaxies, subject to the existence of heavier copies.

Speaker: Jiashuo Zhang (University Of Hong Kong)

TheFutureIsWhispering_slides.pdf

16:00 Phenomenology of Neutrino-Dark Matter Interaction in DSNB and AGN

We investigate a neutrino-scalar dark matter (DM) $νϕ$ interaction encountering distinctive neutrino sources, namely Diffuse Supernova Neutrino Background (DSNB) and Active Galactic Nuclei (AGN). The interaction is mediated by a fermionic particle $F$, in which the $νϕ$ scattering cross section characterizes different energy dependent with respect to the kinematic regions, and manifests itself through the attenuation of neutrino fluxes from these sources. We model the unscattered neutrino flux from DSNB via core-collapse supernova (CCSN) and star-formation rate (SFR), then incorporate the present Super-Kamionkande and future DUNE/Hyper-Kamiokande experiments to set limits on DM-neutrino interaction. For AGNs, NGC 1068 and TXS 0506+056, where the neutrino carries energy above TeV, we select the kinematic region $m^2_F ≫ E_ν m_ϕ ≫ m^2_ϕ$ such that the $νϕ$ scattering cross section features an enhancement at high energy. Furthermore, taking into account the DM spike profile at the center of AGN, we constrain on $m_ϕ$ and scattering cross section via computing the neutrino flux at IceCube, where the $ϕϕ^∗$ annihilation cross section is implemented to determine the saturation density of the spikes.

Speaker: Yu Min Yeh (National Tsing Hua University)

簡報.pptx

16:30 Shimmering darkness: Mapping the evolution of supernova-neutrino-boosted dark matter across the sky

Supernova-neutrino-boosted dark matter (SN$\nu$ BDM) has emerged as a promising portal for probing sub-GeV dark matter, offering the distinctive capability of DM mass differentiation via time-of-flight information. In this work, we randomly generate the spatial locations and ages of core-collapse supernovae (CCSNe) in the Milky Way (MW) over the past one hundred thousand years by Monte Carlo simulation and estimate their cumulative contribution to the present-day BDM flux at Earth. This study aims to address two crucial aspects for DM detection: {\it where} and {\it when} to search for BDM signatures. We systematically demonstrate that a spatial and temporal averaging of the total BDM signal is valid only when the duration of the BDM flux from an individual CCSN greatly exceeds the average time interval between two successive CCSNe in the MW. Particularly in a region when the ratio of BDM kinetic energy to DM mass is less than 5. Otherwise, the BDM signal must be resolved on a per-source basis. For completeness, we also discuss the results obtained using the observed supernova remnant data.

Speaker: Yen-Hsun Lin (Academia Sinica)

Shimmering darkness

Thursday, 26 June

09:30 → 10:30 Keynote Talks: Exploring Physics Beyond the Standard Model via Temperature Observations of Neutron Stars

Convener: Po-Yen Tseng (National Tsing Hua University, Department of Physics)

09:30 Exploring Physics Beyond the Standard Model via Temperature Observations of Neutron Stars

I will discuss how temperature observations of neutron stars provide a unique window to explore physics beyond the Standard Model of particle physics. Neutron stars, with their extreme environments, serve as natural laboratories for testing the limits of our physical understanding. The standard cooling theory, which accounts for the cooling of isolated neutron stars through neutrino and electromagnetic radiation, generally aligns with observational data. However, the presence of hypothetical particles such as axions and dark matter, predicted by theories that extend the Standard Model, could alter this cooling behavior. Axions, for example, increase cooling rates, while dark matter interactions could lead to additional heating. By comparing revised theoretical predictions with observed temperature evolution, we might explore signs of these elusive particles.

Speaker: Koichi Hamaguchi (University of Tokyo)

2025_06_Future_is.pdf

10:30 → 11:00 Coffee Break

11:00 → 12:00 Particle physics from compact objects

Convener: Po-Yen Tseng (National Tsing Hua University, Department of Physics)

11:00 Neutrino Beacons: Illuminating New Physics with Cosmic Messengers

The origin of tiny neutrino masses remains an open question in particle physics, prompting extensions beyond the Standard Model (SM). In this talk, I will present a study of a $U(1)$ gauge extension of the SM that incorporates three generations of Majorana-type right-handed neutrinos. This framework leads to the emergence of a neutral beyond-the-Standard-Model (BSM) gauge boson, denoted as $Z^\prime$, whose interactions can be chiral or flavored.

We explore the potential of high-energy cosmic events, such as gamma-ray bursts (GRBs) and active galactic nuclei (AGNs), to probe $Z^\prime$ neutrino interactions. Specifically, we analyze the process $\nu\nu \to e^+ e^-$, which can contribute to energy deposition in events like GRB221009A, the highest energy GRB observed to date. By estimating the observables of such processes, we constrain the $U(1)$ gauge coupling ($g_X$) and the $Z^\prime$ mass ($M_{Z^\prime}$) under Schwarzschild and Hartle-Thorne scenarios.

Additionally, we investigate $\nu$-dark matter (DM) scattering mediated by Z′ bosons, utilizing data from the IceCube Neutrino Observatory. By considering high-energy neutrinos from cosmic sources such as the blazar TXS0506+056 and the active galaxy NGC1068, along with Cosmic Microwave Background (CMB) and Lyman-$\alpha$ data, we further constrain the $g_X$–$M_{Z^\prime}$ parameter space.

Finally, we compare our findings with current and prospective bounds from scattering experiments, beam-dump experiments, and measurements of the anomalous magnetic moment (g–2). This comprehensive analysis highlights the complementarity of astrophysical observations in probing chiral and flavored $Z^\prime$ bosons.

Speaker: Shivasankar Kandasamy Arunachalam (Hokkaido University)

ShivaSankar_2308.14483_Future_is_whispering_June2025.pdf

11:30 Flavor Equilibration of Supernova Neutrinos: Exploring the Dynamics of Slow Modes

Neutrinos experience collective flavor conversion in extreme astrophysical environments such as core-collapse supernovae (CCSNe). One manifestation of collective conversion is slow flavor conversion (SFC), which has recently attracted renewed interest owing to its ubiquity across different regions of the supernova environment.
In this study, we systematically examine the evolution of kinematic decoherence in a dense neutrino gas undergoing SFC, considering lepton number asymmetries as large as $30\%$.
Our findings show that the neutrino gas asymptotically evolves toward a generic state of coarse-grained flavor equilibration which is constrained by approximate lepton number conservation.
The equilibration occurs within a few factors of the inverse vacuum oscillation frequency, $\omega^{-1}$, which corresponds to (anti)neutrinos reaching near flavor equipartition after a few kilometers for typical supernova neutrino energies.
Notably, the quasi-steady state of the neutrino number densities can be quantitatively described by the neutrino-antineutrino number density ratio $n_{\bar{\nu}_e}/n_{\nu_e}$ alone.
Such a simple estimation opens new opportunities for incorporating SFC into CCSN simulations, particularly in regions where SFC develops on scales much shorter than those of collisions.

Speaker: Mr Heng-Hao Chen (Academia Sinica)

2025_Jun_student_talk.pdf

12:00 → 13:30 Lunch Break

13:30 → 14:30 Keynote Talks: Uncovering "Taiwanese Dark Matter" (ultra-light bosons) with JWST and Implications for High Energy Physics

Convener: Sut-Ieng Tam (NYCU, IoP)

13:30 Uncovering "Taiwanese Dark Matter" (ultra-light bosons) with JWST and Implications for High Energy Physics

We show how light axions generic in String Theory provide definitive predictions that are borne out by deep lensing and galaxy formation data from JWST. This wave-like behaviour was predicted by pioneering simulations in Taiwan, with pervasive substructure on the de Broglie scale that is very distinguishable from standard heavy particle CDM. This dark matter solution reinforces the absence of heavy partner MSSM candidates at the LHC and we argue strengthens the case for unification at the EW scale.

Speaker: Tom Broadhurst (University of the Basque Country and DIPC)

14:30 → 15:00 Dark Matter

Convener: Sut-Ieng Tam (NYCU, IoP)

14:30 Constraints on extended axion structures from the lensing of fast radio bursts

Axions are hypothetical pseudoscalar particles that have been regarded as promising dark matter (DM) candidates. On the other hand, extended compact objects such as axion stars, which are supported by gravity and axion self interactions, may have also been formed in the early Universe and comprise part of DM. In this work, we consider the lensing of electromagnetic signals from distant sources by axion stars as a way to constrain the properties of axion stars and fundamental axion parameters. Accounting for the effect of the finite size of the axion star, we study the lensing effect induced by gravity and by axion-photon interactions. The latter effect is frequency dependent, and is relevant in the low frequency band, which motivates the use of fast radio burst (FRB) signals as a probe. We calculate the predicted number of lensed FRB events by specifying the fundamental axion parameters, axion star radial profile, fraction of DM residing in axion stars, and imposing lensing criteria based on the flux ratio and time delay between the brightest images from lensing. Assuming an optimistic case of $10^4$ observed FRB events, and a timing resolution of $1\,\mu {\rm s}$, the lack of observed FRB lensing events in CHIME allows us to probe axion stars with mass $\gtrsim 10^{-2} M_\odot$, corresponding to axion masses $\lesssim 10^{-10}\,{\rm eV}$ and for negligible axion-photon couplings. Even lighter axion stars up to $\sim 10^{-3} M_\odot$ can be probed, assuming axion-photon couplings of at least $10^{-6}\,{\rm GeV}^{-1}$. Our results indicate that while FRB lensing by axion stars leads to sensitivities that are competitive with conventional microlensing searches operating in the optical band, it remains a challenge to probe axion-photon induced lensing effects.

Speaker: Kuan-Yen Chou (Department of Physics, National Tsing Hua University)

KYC_Whispering.pdf

15:00 → 15:30 Coffee Break

15:30 → 16:00 Feebly interacting particles

Convener: Priyanka Sarmah (NTHU)

15:30 Probing Terrestrial Relic Neutrino Charge with Mach-Zehnder Interferometer

We propose a novel mechanism to detect terrestrial cosmic neutrino background's (CNB) limit of electric charge by employing Mach-Zehnder interferometer with asymmetrical arm placement – one at the Earth’s surface and the other is placed underground. Assuming that relic neutrinos possess a small but nonzero charge, their coherent forward scattering with photons induces measurable phase shift in a laser beam. From the terrestrial CNB overdensity resulting from weak interaction induced by neutrino-antineutrino asymmetry near the surface of the earth, we formulate the quantum interaction Hamiltonian and analyze the induced phase shift under realistic interferometric constraints. The projected sensitivity reaches of our setup are evaluated under three operation regimes: the standard quantum limit (SQL), the Heisenberg limit, and the super-Heisenberg limit. For neutrino masses $m_\nu=0.05$ eV, our scheme can probe fractional electric charges $\epsilon_\nu$ as small as $9.3 \times 10^{-11}$, $1.6 \times 10^{-16}$, and $2.9 \times 10^{-22}$, respectively. The proposed interferometric strategy surpasses existing laboratory bounds and even astrophysical constraints when operating in the Heisenberg or super-Heisenberg mode.

Speaker: Vincent Gene Otero (National Taiwan Normal University)

MZ Interferometer_TFW.pdf

16:00 → 17:00 Gravitational aspects of particle physics

Convener: Priyanka Sarmah (NTHU)

16:00 Gravitational Dressing Operators and Radiative Observables from Binary Systems

In recent years, classical limits of scattering amplitudes have emerged as a powerful tool for deriving state-of-the-art results for gravitational wave observables from interacting binary compact objects. In this talk, I will explore gravitational dressing operators from the worldline formalism and discuss their significance for late time radiative observables. We will first consider how fluctuations around the asymptotic trajectories of the scattered compact objects can be used to derive a gravitational dressing operator in a multiple soft graviton expansion. We will then use this operator, considered up to collinear double soft graviton terms, to find late time results for the waveform, emitted momentum and angular momentum. I will conclude with results from ongoing work that relates the gravitational dressing exponent up to double soft graviton order, and the double soft graviton factor for scattering amplitudes.

Speaker: Karan Fernandes (NTNU)

Fernandes_TFW.pdf

16:30 The possibility of detecting dark matter with gravitational wave interferometers

We discuss the prospects for discovering macroscopic Dark Matter (DM) using large-scale ground-based gravitational wave (GW) detectors. Here, as an example, we consider a DM candidate with long-range Yukawa-like interactions in the kg- to tonne-scale mass range, where the analysis can potentially be further generalised for other DM models. The DM in this mass range will produce a signal that is significant enough for detection at the proposed detector. We consider the interaction range to be on the order of kilometers, thus the DM will interact with multiple GW detector mirrors simultaneously. This can lead to some interesting phenomena, such as signal enhancement or suppression and directional sensitivity. This long-range interaction also results in large cross sections for interactions between the DM and ordinary matter, compensating for the lower number density of the DM. Based on the simulation of the interaction between dark matter (DM) and the mirror suspension system, we can determine the detector response. We will further refer to this signal output from the detector as a "template." We will then attempt to search for these templates in the LIGO open data. The procedure for identifying a particular template from a noisy background is well-established for GW analysis, and is often known as "matched filtering". Through this study, we aim to explore the possibility of detecting, or setting limits on, this DM model and develop a standardised platform for analysing DM models using GW data.

Speaker: Hsiang-Chieh Hsu (Institute of Physics, Academia Sinica)

2025_Future_is_Whispering_HC_Hsu.pdf

Friday, 27 June

09:30 → 10:30 Special session

Convener: C.-J. David Lin (Institute of Physics, National Yang Ming Chiao Tung University)

09:30 Probing the heart of the matter with supercomputers

Nucleons (that is, protons and neutrons) are the building blocks of all ordinary matter, and the study of nucleon structure is a critical part of frontier research to unveil the mysteries of the universe and our existence. Gluons and quarks are the underlying degrees of freedom that explain the properties of nucleons, and fully understanding how they contribute to the properties of nucleons (such as mass or spin structure) helps to decode the last part of the Standard Model that rules our physical world. After more than half a century of large-scale experimental efforts, there are still many unknowns concerning the theory quantum chromodynamics (QCD), the branch of the Standard Model describing how gluons strongly interact with themselves and with quarks, binding both nucleons and nuclei. Using supercomputers and a theoretical tool called "lattice QCD", we can simulate the theory that dominates the universe at the femtoscale and unveil its diverse phenomenology, including some properties that are hard to determine in experiments. Few selected recent Lattice-QCD examples and their impacts will be briefly discussed.

Speaker: Prof. Huey-Wen Lin (Michigan State University)

10:00 A Search for Planet Nine with IRAS and AKARI Data

The outer solar system is theoretically predicted to harbour an undiscovered planet, often referred to as P9. Simulations suggest that its gravitational influence could explain the unusual clustering of minor bodies in the Kuiper Belt. However, no observational evidence for P9 has been found so far, as its predicted orbit lies far beyond Neptune, where it reflects only a faint amount of Sunlight. This work aims to find P9 candidates by taking advantage of two far-infrared all-sky surveys, which are IRAS and AKARI. The epochs of these two surveys were separated by 23 years, which is large enough to detect the ~3'/year orbital motion of P9. We use a dedicated AKARI Far-Infrared point source list for our P9 search - AKARI Monthly Unconfirmed Source List, which includes sources detected repeatedly only in hours timescale, but not after months. We search for objects that moved slowly between IRAS and AKARI detections given in the catalogues. First, we estimated the expected flux and orbital motion of P9 by assuming its mass, distance, and effective temperature to ensure it can be detected by IRAS and AKARI, then applied the positional and flux selection criteria to narrow down the number of sources from the catalogues. Next, we produced all possible candidate pairs whose angular separations were limited between 42' and 69.6', corresponding to the heliocentric distance range of 500 - 700 AU and the mass range of 7 - 17 Earth masses. There are 13 pairs obtained after the selection criteria. After image inspection, we found one good candidate, of which the IRAS source is absent from the same coordinate in the AKARI image after 23 years and vice versa. However, AKARI and IRAS detections are not enough to determine the full orbit of this candidate. This issue leads to the need for follow-up observations, which will determine the Keplerian motion of our candidate.

Speaker: Tomo Goto (IoA)

10:30 → 11:00 Coffee Break

11:00 → 12:00 Keynote Talks: New open window for dark matter with Memory Burden Effect in evaporating black holes (online)

Convener: C.-J. David Lin (Institute of Physics, National Yang Ming Chiao Tung University)

11:00 New open window for dark matter with Memory Burden Effect in evaporating black holes

I will review the current state of the theories and observations of the primordial black holes (PBHs). In particular, I will discuss how a new window for PBH to become dark matter opens when the memory burden effect acts on the evaporating PBHs.

Speaker: Kazunori Kohri (NAOJ / KEK)

Kohri-Online-NYCU20250627.pdf

12:00 → 13:30 Lunch Break

13:30 → 14:30 Dark Matter

Convener: KINGMAN CHEUNG (NTHU)

13:30 Probing the Gauge-boson Couplings of Axion-like Particle at the LHC

In this work, we calculate the sensitivities on the gauge-boson couplings $g_{aZZ}$, $g_{aZ\gamma}$, and $g_{aWW}$ of an axion-like particle (ALP) that one can achieve at the LHC with $\sqrt{s}=14$ TeV and integrated luminosities of 300 fb$^{-1}$ (current run)
and 3000 fb$^{-1}$ (High-Luminosity LHC). We focus on the associated production processes $pp\to Za \to (l^+l^-)(\gamma\gamma)$ and $pp\to W^\pm a \to (l^\pm \nu)(\gamma\gamma)$. We show that better ensitivities on these gauge couplings can be achieved at the LHC for $M_a = 1-100$ GeV, down to the level of $10^{-4}\,{\rm GeV}^{-1}$. In conclusion, this study emphasizes the significance of the investigated channels in constraining the ALP couplings at the LHC, offering valuable insights for future experiments dedicated to ALP detection.

Speaker: Chen Wang (National Tsing Hua University)

0627交大.pdf

14:00 JUNO sensitivity to resonance-enhanced MeV dark matter annihilation in the galactic halo

JUNO sensitivity to the annihilation cross section of MeV dark matter (DM) into neutrinos in the galactic halo (A. Abusleme et al. [JUNO], JCAP 09, 001 (2023)) constrains the DM-extended $U(1)_{L_\mu - L_\tau}$ model, characterized by the $Z'$ boson with mass $m_{Z’}$, the coupling $g_{Z’}$ between $Z’$ and the second and third generations of leptons, and the coupling $g_{\chi}$ between DM and $Z’$. Focusing on light DM with masses below 100 MeV, we study the annihilation channel $\chi\chi \to Z' \to \nu_{\mu, \tau}\bar{\nu}_{\mu, \tau}$ in the galactic halo with $m_{Z’}\approx 2m_{\chi}$. We impose the condition that the DM relic density matches the observed value $\Omega_\chi h^2=0.12$, which fixes the value of $\langle \sigma v \rangle$ in the early universe. Under this condition, we predict the value of resonance-enhanced $\langle \sigma v \rangle$ in the present-day universe as a function of the coupling product $g_{Z’}\cdot g_{\chi}$. We discuss the possibility of testing this resonance-enhanced annihilation by JUNO detector.

Speaker: Ms Thi Dieu Hien Van (NYCU-IOP)

14:30 → 15:00 Coffee Break

15:00 → 15:30 Particle physics from compact objects

Convener: KINGMAN CHEUNG (NTHU)

15:00 Probing Jet Composition in Extreme Mass Ratio Black Hole Binaries through Periodic Emission Features

Largerly due to the spectral degeneracy in high-energy observations, the composition of black hole jets, wheter lepton-dominated or baryon-loaded, remains a longstanding open question. We propose that extreme mass ratio (EMR) black hole binaries, particularly systems involving a secondary microquasar interacting periodically with the accretion flow of a primary supermassive black hole, can serve as natural laboratories for disentangling jet composition. The periodic jet–accretion collisions in the system can result in distinct emission signatures shaped by underlying leptonic or hadronic processes. By modeling how these periodic features vary with jet composition, we explore that multi-frequency observations can effectively discriminate between jet compositions. These electromagnetic imprints offer a complementary probe to the emerging multi-messenger approaches for uncovering the nature of black hole relativistic jets.

Speaker: Hung-Yi Pu (National Taiwan Normal University)

15:30 → 16:00 Welcome & Farewell: Farewell

Convener: Prof. Sut-Ieng Tam (NYCU, IoP)

slide.pdf