Cosmological stasis is a phenomenon in which multiple energy components with different equation-of-state parameters maintain constant abundances for an extended period despite the expansion of the universe. In this talk, I review how stasis arises and discuss the possible implications of this phenomenon in observations. These include the enhancement in the growth of matter density...
In causal set theory, spacetime is represented by a locally finite partially ordered set. The abundances of small combinatorial structures can be used to recover information about its continuum geometry. We study how chains and 2-pixies can be used to recover local cosmological quantities in four-dimensional, spatially flat FLRW spacetimes. For causal diamonds centered on a comoving observer,...
We compute electromagnetic radiative corrections in the inverse beta decay at reactor antineutrino energies within the heavy baryon chiral perturbation theory, provide the most accurate cross-section predictions for this process, present a complete error budget, and investigate impact on the energy reconstruction at JUNO. For the first time, we consistently include quantum electrodynamics,...
Chiral gravitational wave backgrounds are predicted in many well-motivated mechanisms. We investigate the detection of Chiral GWBs using a network of detectors under arbitrary configurations. We also propose a dipole pulsar timing array, which demonstrates sensitivity to Chiral gravitational wave backgrounds from the nanohertz to microhertz regime.
How should one define a renormalization scale when spacetime geometry itself is quantum and dynamical? I will discuss a relational formulation of coarse graining in which physical resolution and mode ordering are defined by dynamical geometric observables, while RG flow remains distinct from physical clock evolution.
I will then present a Hamiltonian implementation using the non-perturbative...
The early universe is a natural laboratory for high-energy physics, and gravitational waves, as direct probes of this epoch, inherently carry rich information related to high-energy physics. Silk damping, resulting from dissipation in the cosmic fluid, is a significant physical phenomenon in the early universe. In this talk, I will introduce our first study on Silk damping in induced...
The memory burden (MB) effect can dramatically slow black hole evaporation once half of the initial mass is radiated, allowing very light primordial black holes (PBHs) to persist today as dark matter (DM). We probe this scenario across three complementary messengers.
Using LHAASO ultra-high-energy gamma-ray spectra of four Galactic sources, we constrain PBHs with masses 10^9 g. From 10 years...
Dark matter (DM), a fundamental cosmic component, motivates the study of its influence on black hole (BH) shadows, especially for spinning BHs confirmed by EHT observations. This work generalizes the Schwarzschild BH surrounded by DM to an axisymmetric Kerr BH using the Newman–Janis Algorithm (NJA), investigating the resulting event horizon and ergosphere structures. Employing null geodesics,...
Bootstrapping provides theoretical constraints of the parameter space allowed by the S-matrix properties: analyticity, unitarity, crossing symmetry. It has been applied to constrain different theories without making assumptions about their ultraviolet completions. However, its application in the forward limit of the scattering amplitudes is problematic when considering graviton exchange.
In...
Large primordial curvature perturbations can produce primordial black holes (PBHs) and inevitably generate a scalar-induced stochastic gravitational-wave background upon horizon re-entry. In this talk, based on our recent work arXiv:2609.12867, we will present constraints from the combined LIGO–Virgo–KAGRA O1–O4a data on two representative inflationary mechanisms for producing such...
Cosmological correlators are calculated through the in-in formalism in (quasi-)de Sitter background. Their effective description is best represented by a reduced density matrix. In this talk, I will first review the differences between the usual EFT used in scattering amplitude calculations and the Schwinger-Keldysh EFT for correlators. I will then discuss the reduced density matrix for a...
Non-attractor inflation has drawn significant attention as a class of inflationary models due to its potential to generate primordial black holes (PBHs). However, calculating the one-loop corrections to curvature perturbations in these models has sparked considerable theoretical controversy. We find that symmetry serves as a crucial clue in such loop calculations, and the Ward identity is...
In this talk, I will discuss the focusing of timelike geodesic congruences in $f(Q)$ gravity. I will first introduce geodesic deviation in symmetric teleparallel geometry and the modified Raychaudhuri equation obtained under a Weyl-type nonmetricity ansatz and an additional nonmetricity–acceleration condition. I will then present a focusing condition expressed in terms of the matter...
Entanglement harvesting transfers quantum field correlations to localized probes, yet whether these correlations can alter stable strategic behavior has remained unclear. We formulate a quantum-input game in which two Unruh–DeWitt detectors harvest vacuum entanglement from a free massless scalar field in $(3+1)$-dimensional Minkowski spacetime. A referee converts this state into payoffs using...
We present a mechanism to solve the CP-strong problem with two heavy axions in a composite Higgs . An $Sp(8)$ technicolour group drives electroweak symmetry breaking by producing the Higgs as a pseudo-Nambu–Goldstone boson of the associated flavour symmetry breaking. The same sector generates the Standard Model Yukawa hierarchies through fundamental partial compositeness. At high energy,...
We introduce an alternative approach to gravitational-wave (GW) detection in which GW information is encoded in the orbital angular momentum (OAM) states of photons. Starting from the propagation of vortex light in linearized gravity, we show that interaction with a GW induces transitions from an initial photon OAM state to neighboring OAM sidebands, providing a different optical observable of...
In this work, we address a foundational challenge in quantum field theory on curved spacetime by developing a consistent framework in spherically symmetric loop quantum gravity. We introduce a methodology for defining meaningful superpositions of quantum geometry and matter states near the semiclassical apparent horizon. This is achieved by identifying a restricted subspace of the...
Every rapidly spinning neutron star with slight asymmetry would broadcast a continuous hum of gravitational waves (GW). None of these signals has been detected yet, but the silence itself is measurable: searches now set upper limits on the GW amplitude of dozens of known pulsars, and for a growing subset those limits dig below the energy budget available from the stars' own spin-down. We ask...
The multi-lepton anomalies observed at the LHC have motivated models with new scalar resonances, predicting a scalar at $150\pm5$ GeV. A narrow excess near $m_S=152\pm1$ GeV was observed in Run 2 data in the $\gamma\gamma$, $Z\gamma$, and $W^+W^-$ channels with a significance surpassing $5\sigma$. In this work, we investigate a new excess in the ATLAS Run 3 data using diphoton production in...
Neutrino self-interactions mediated by a light scalar offer a compelling resolution to cosmological tensions and may naturally arise in neutrino mass generation mechanisms. When the scalar also couples to a light dark-sector fermion, supernova neutrinos can resonantly annihilate with the cosmic neutrino background (C$\nu$B) into invisible dark radiation, depleting the flux en route to Earth....
We apply the universal two-zero texture (UTZT) to all quark and lepton mass matrices in the SO(10) grand unified framework. With charged fermion masses fixed at their best-fit values, this texture contains only seven free parameters to account for nine flavor observables, rendering it highly predictive. Motivated by the recent JUNO indication in favor of the normal ordering of light neutrino...
