Description
List of posters can be found under the contribution list.
Presentation materials
Analysis of EDGES data shows an absorption signal of the redshifted 21-cm line of atomic hydrogen at
The recent
As primordial black holes (PBHs) are one possible candidate for dark matter (DM), various constraints on PBHs have been placed in wide mass ranges. Especially in the mass range above 10^-1 M_sun, the method using gas accretion on PBH has been taken. Here, we newly consider the gas accretion process in dust tori in active galactic nuclei (AGNs). The dust torus region is typically the central...
Light relics are new degrees of freedom which decoupled from the Standard Model while relativistic. Nearly massless relics will both contribute to the radiation energy budget and, for relics with masses on the eV scale (meV-10 eV), will become non-relativistic before today, behaving as matter instead of radiation. Such relics leave an imprint in the large-scale structure of the universe as...
We derive an equation of state (EOS) for magnetized charge-neutral nuclear matter relevant for a neutron star (NS). The calculations are performed within an effective chiral model based on the generalization of the ฯ model with nonlinear self-interactions of the ฯ mesons along with the ฯโฯ cross-coupling term. This model is extended by introducing the contributions of a strong magnetic field...
We study possible particle-antiparticle asymmetry in the dark sector in two distinct scenarios. In both the scenarios dark matter (DM) scatterings play defining role in deciding the asymmetry as well as the density. In the first case, we demonstrate a general semi-annihilation of DM particles, leading to maximal asymmetry in DM sector (Ref :JHEP 08 (2020), 149). In the second case, We find an...
The baryon asymmetry of the universe may be explained by rotations of the QCD axion in field space and baryon number violating processes. We consider the minimal extension of the Standard Model by a non-Abelian gauge interaction,
Axion-like particles (ALPs), a class of pseudoscalars common to many extensions of the Standard Model, have the capacity to drain energy from the interiors of stars and consequently can be constrained through their impact on stellar evolution. In this talk I will derive a new constraint on ALPs which couple exclusively to photons, based on their effects on the white dwarf initial-final mass...
Supernova (SN) explosions are the most powerful cosmic factories of all-flavors, MeV-scale, neutrinos. Their detection is of great importance not only for astrophysics, but also to shed light on neutrino properties. Since the first observation of a SN neutrino signal in the 1987, the international network of SN neutrinos observatories has been greatly expanded, in order to detect the next...
In the early universe, primordial black holes (PBHs) can no longer be described by the simple Schwarzschild metric-- we need a metric which is locally surrounded by the cosmological fluid and asymptotically FLRW. It turns out that the phenomenology of PBHs is very sensitive to the choice of such a metric. In particular, the Thakurta metric stands out as perhaps the most justifiable metric for...
A large amount of data from dwarf galaxies to galaxy clusters appears to indicate that dark matter (DM) acts like a collisional fluid at galaxy scales to a collisionless fluid at the scale of galaxy clusters. We will discuss a particle physics model with the standard model extended with a gauged abelian hidden sector to explain this phenomenon. In this model dark matter consists of fermions of...
Dark matter (DM) particles are predicted to decay into Standard Model particles which would produce signals of neutrinos, gamma-rays, and other secondary particles. Neutrinos provide an avenue to probe astrophysical sources of DM particles. We review the decay of dark matter into neutrinos over a range of dark matter masses from MeV/c2 to ZeV/c2. We examine the expected contributions to the...
We present prospects for discovering dark matter scattering in gravitational wave detectors. We study how a potential signal from a dark matter particle compares to typical background noises in gravitational wave detectors. The dark matter signal is modelled as an elastic scattering event with the interferometer components. For the background we focus on suspension thermal noise and quantum...
Commonly known as Boltzmann suppression is the key ingredient to create chemical imbalance for thermal dark matter. In a degenerate/quasi degenerate dark sector chemical imbalance can also be generated from a different mechanism which is analogous to the radioactive decay law, known as co-decaying dark matter. In this work, we have studied the dynamics of a multicomponent thermally decoupled...
The 5:1 ratio between the cosmological mass densities of dark matter (DM) and visible matter (VM) hints at a deep connection between the origins of the two sectors. While models connecting the number densities of DM and VM have been well-explored, very little work has focused on relating the mass of DM to the proton mass. This can be achieved if the DM is a confining state of a dark QCD gauge...
In certain extensions of the Standard Model, the interactions between some new scalars and SU(2)_L Higgs doublet(s) can cause the electroweak(EW) symmetry to remain broken at temperatures well above the EW scale. We found that new fermions from renormalizable models can also induce this EW symmetry non-restoration effect, provided that they have the appropriate temperature-dependent masses....
In the scenario in which the axion is born after inflation, the field develops significant inhomogeneity and evolves in a highly nonlinear fashion. Understanding the eventual abundance and distribution of axionic dark matter in this scenario therefore requires dedicated numerical simulations. Here, we go beyond the QCD axion, and perform a suite of simulations for a range of possible...
We investigate the resummation of infrared logarithms in inflationary Universe from holographic perspective. By the renormalization group, we derive gravitational Fokker-Planck and Langevin equations as the effective theory at the Horizon scale. We investigate the time evolution of the de Sitter entropy
Simplified models of light new physics provide an important theoretical and experimental benchmark. Models that extend such minimal scenarios by introducing other degrees of freedom are popular and well motivated ways to go beyond the Standard Model (SM). In this talk, I will focus on the light dark Higgs portal that connects the dark sector consisting of, among others, heavy, TeV-scale...
We explore a new kind of NLED field as a source of gravity, which can accelerate the universe during the inflationary era. We propose a new type of NLED lagrangian which is characterized by two parameters: ฮฑ (dimensionless parameter) and ฮฒ (dimensionful parameter). We investigate the classical stability and the causality aspects of this model of inflationary expansion by demanding that the...
Next energy frontier accelerators like ILC or CLIC are with immense possibilities to improve our understanding with nature's fundamental building block and to discover new particles e.g. WIMP dark matters along with other physics phenomena. In scenarios where dark matter does not or feebly couple with quarks, we can consider the dominant coupling of dark matter with charged leptons. We...
An abundance of hints from recent neutrino experiments leads to the hypothesis of the existence of light sterile neutrinos; however, there are also many constraints from laboratory experiments experimentally and cosmological observations that constrain its mixing and mass. In light of these observations, we present a new model of light sterile neutrinos that aims to elucidate this confusing...
The standard model(SM) is augmented by a
Dark matter is one of the cornerstones of the standard cosmological model although we do not know its fundamental nature. Huge effort has been made in order to perform a direct detection of this dark matter component but up to now we have only seen it interacting gravitationally. In this regard the indirect detection is a promising method to search for dark matter, where we try to look at...
We present a simple extension of the Standard Model with three right-handed neutrinos in a SUSY framework, with an additional U(1)_F abelian flavor symmetry with a non standard leptonic charge for lepton doublets and arbitrary right-handed charges. We show how it is possible to provide the correct predictions for the mixing angles of the PMNS matrix and for the r=(โm_sun)^2/(โm_atm)^2...
Particulate dark matter captured by a population of neutron stars distributed around the galactic center while annihilating through long-lived mediators can give rise to an observable neutrino flux. We examine the prospect of an idealized gigaton detector like IceCube/KM3Net in probing such scenarios. Within this framework, we report an improved reach in spin-dependent and spin-independent...
In secluded dark sector scenario, thermal equilibrium between dark and visible sector depends on the strength of portal coupling. To study the non-adiabatic evolution of the dark sector, we have considered a
A mechanism for the formation of primordial black holes is proposed. Here, heavy quarks of a confining gauge theory produced by de Sitter fluctuations are pushed apart by inflation and get confined after horizon re-entry. The large amount of energy stored in the colour flux tubes connecting the quark pair leads to black-hole formation. These are much lighter and can be of higher spin than...
We study neutrino oscillations within the framework of extended theories of gravity. Based on the covariant reformulation of Pontecorvoโs formalism, we evaluate the oscillation probability of neutrinos propagating in static spacetimes described by gravitational actions quadratic in the curvature invariants. Calculations are carried out in the two-flavor approximation, for oscillations both in...
Based on the geometry of the codimension-2 surface in general spherically symmetric spacetime, we give a quasi-local definition of a photon sphere as well as a photon surface. This new definition is the generalization of the one provided by Claudel, Virbhadra, and Ellis but without referencing any umbilical hypersurface in the spacetime. The new definition effectively excludes the photon...
The inferred abundance of dark matter in the Universe could be explained with heavy decaying dark matter. According to heavy dark matter models, the decay of dark matter in astronomical objects can produce highly energetic neutrinos detectable at the Earth. The IceCube Neutrino Observatory, located at the geographic South Pole, is to date the worldโs largest neutrino telescope. Over the past...
Effective range theory, which was originated in Bethe, was developed to study nucleon scattering. We applied this in the context of self-interacting dark matter (SIDM). We studied what kind of combination of parameters fit to the MCMC simulation of dark matter cross section from dwarf scale to cluster scale. As a result, scattering length is longer than our naive expectation. So we...
Heavy neutral leptons (HNLs) have been proposed to extend the standard model to explain the MiniBooNE anomaly. We demonstrate that, in the minimal scenario, this model is ruled out by a combination of neutrino beam experiments and cosmological constraints. However, HNLs could be portals to a dark sector. An extension of this model that incorporates a dark U(1) gauge theory can avoid the...
