Conveners
Afternoon Session: I
- Huaike Guo (University of Chinese Academy of Sciences)
Afternoon Session: II
- Yun Jiang (Sun Yat-sen University)
Afternoon Session: III
- Wei Chao (BNU)
Afternoon Session: IV
- Tianjun Li (Institute of Theoretical Physics, Chinese Academy of Sciences)
We present a new framework of grand unification that is equipped with an axion solution to the strong CP problem without a domain wall problem when the Peccei–Quinn (PQ) symmetry is spontaneously broken after inflation. Our grand unified theory (GUT) is based on a symmetry breaking pattern, SU(10) × SU(5)1 → SU(5)V ⊃ SU(3)C × SU(2)L × U(1)Y, where SU(5)1 and a special embedding of SU(5)2 ⊂...
The hot interiors of massive stars in the later stages of their evolution provide an ideal place for the production of heavy axion-like particles (ALPs) with mass up to O(100 keV) range. We show that a fraction of these ALPs could stream out of the stellar photosphere and subsequently decay into two photons that can be potentially detected on or near the Earth. In particular, we estimate the...
The preferred axion models are a set of minimal QCD axion models that abide by standard cosmological constraints in the post-inflationary PQ breaking scenario. It turns out that some of these models predict a period of early matter domination, driven by the additional particle content. I will discuss how this leads to a greater number of models with consistent cosmologies and alters the axion...
Rotating primordial black holes (PBHs) in the early universe can emit particles through superradiance, a process particularly efficient when the particle's Compton wavelength is comparable to the PBH's gravitational radius. Superradiance leads to an exponential growth of particle occupation numbers in gravitationally bound states. We present an analysis of heavy bosonic dark matter (DM)...
DarkSHINE is a fixed-target experiment initiative to search for light Dark Matter and mediators at SHINE (Shanghai high repetition rate XFEL and extreme light facility, being the 1st hard X-ray FEL in China) under construction targeting completion in 2025/2026. DarkSHINE aims to search for the new mediator, Dark Photon, bridging the Dark sector and the ordinary matter. In this contribution, we...
We present a detailed phenomenological study of a light dilaton $\varphi$, arising from the spontaneous breaking of approximate scale invariance in a nearly conformal theory. Particular care is taken to account for the dilaton’s enhanced coupling to photons, originating from loops of the conformal sector, which significantly shortens its lifetime and relaxes constraints from $K \to \pi + {\rm...
Though most axion dark matter experiments use static background fields, the axion also induces transitions between oscillating modes of an excited cavity. This "heterodyne" detection approach benefits from the very high quality factors available in superconducting cavities, and has a parametrically enhanced signal power at low axion masses. I will review recent experimental progress on this...
QCD axion can explain the strong CP problem and dark matter (DM) simultaneously. If the Peccei-Quinn (PQ) symmetry is spontaneously broken after inflation, string-wall network would dominate the energy density in the Universe. In this talk, we consider a mixing coupling of the PQ scalar with a light scalar field which induces an extra axion potential. When the PQ scalar is mixed nonlinearly,...
Constraints on axions as hot dark matter (HDM) from $\Delta N_{\rm eff}$ provide an important and independent probe of axion properties. In hadronic axion models such as the KSVZ model, the axion thermalization rate below the QCD crossover temperature is typically estimated under two key assumptions: (1). thermal corrections to the reaction amplitudes are negligible at $T < M_{\rm th}/2$ with...
Ultralight charged bosons can extract energy, angular momentum, and charge from a Kerr–Newman black hole (BH) due to superradiant instability, resulting in the formation of a BH–condensate system. In this work, we focus on a scalar field with a minicharge and numerically investigate in detail the evolution of this system. We find that even a tiny initial mass asymmetry between the positively...
As an alternative theory to cold dark matter (CDM), fuzzy dark matter (FDM) has recently attracted widespread attention. FDM consists of ultra-light bosons with masses around 10^{-22} eV. At typical galactic velocities, their de Broglie wavelength can reach kiloparsec (kpc) scales, thereby exhibiting unique wave-like behavior on galactic scales. This leads to complex evolutionary dynamics and...
Superconducting radio-frequency (SRF) cavities, renowned for their exceptionally high quality factors (~10^10), have emerged as powerful tools for probing fundamental physics beyond the Standard Model. In this talk, I will introduce the first-ever scan search for dark photon dark matter using a tunable SRF cavity, achieving unprecedented sensitivity to the kinetic mixing coefficient parameter...
I will present a composite dark matter framework based on the confinement dynamics of a dark SU(N) Yang-Mills sector. This theory gives rise to composite bound states, glueballs, that in the absence of fermions serve as dark matter candidates. I will review recent developments in understanding glueball production in the early Universe and delineate the parameter space where they can account...
