Related papers: New Bounds on Heavy QCD Axions from Big Bang Nucle…
We show that Big Bang Nucleosynthesis (BBN) significantly constrains axion-like dark matter. The axion acts like an oscillating QCD $\theta$ angle that redshifts in the early universe, increasing the neutron-proton mass difference at…
In this paper we consider the effects on big bang nucleosynthesis (BBN) of the hadronic decay of a long-lived massive particle. If high-energy hadrons are emitted near the BBN epoch ($t \sim 10^{-2}$ -- $10^2 \sec$), they extraordinarily…
We present updated and improved Big Bang Nucleosynthesis (BBN) constraints on heavy, long-lived beyond the Standard Model (BSM) relics $\phi$ decaying into pairs of Standard Model particles, covering a comprehensive set of two-body decay…
Big Bang Nucleosynthesis (BBN) has increasingly become the tool of choice for investigating the permitted variation of fundamental constants during the earliest epochs of the Universe. Here we present a BBN calculation that has been…
We examine Big Bang nucleosynthesis (BBN) in the case of inhomogenous neutrino degeneracy, in the limit where the fluctuations are sufficiently small on large length scales that the present-day element abundances are homogeneous. We…
We show that the predicted primordial helium production is significantly reduced when new measurements of the neutron lifetime and the implied enhancement in the weak reaction rates are included in big-bang nucleosynthesis. Therefore, even…
Primordial nucleosynthesis is one of the three historical evidences for the big bang model, together with the expansion of the universe and the cosmic microwave background. Now that the number of neutrino families and the baryonic densities…
We revisit the joint constraints in the mixed hot dark matter scenario in which both thermally produced QCD axions and relic neutrinos are present. Upon recomputing the cosmological axion abundance via recent advances in the literature, we…
Heavy neutral leptons (HNLs) are constrained by requirements of Big Bang Nucleosynthesis (BBN) as their decays significantly impact the formation of the primordial elements. We propose here a model where the primary decay channel for the…
We estimate the Big Bang nucleosynthesis (BBN) constraint on the majoron in the mass range between $1\,{\rm MeV}$ to $10\,{\rm GeV}$ which dominantly decays into the standard model neutrinos. When the majoron lifetime is shorter than…
To elucidate the significance of the effect of systematic uncertainties in light element abundance estimates on cosmological bounds derivable from Big Bang Nucleosynthesis (BBN) we present tables giving bounds on $\Omega_{baryon}$ and…
We study the big-bang nucleosynthesis (BBN) with the long-lived exotic particle, called X. If the lifetime of X is longer than \sim 0.1 sec, its decay may cause non-thermal nuclear reactions during or after the BBN, altering the predictions…
Big-bang nucleosynthesis (BBN) describes the production of the lightest nuclides via a dynamic interplay among the four fundamental forces during the first seconds of cosmic time. We briefly overview the essentials of this physics, and…
A cosmological model with a time-varying mass of electrons seems a promising solution for the so-called Hubble tension. We examine the big bang nucleosynthesis (BBN) constraints on the time-varying electron mass model, because a larger…
We study the big-bang nucleosynthesis (BBN) scenario with late-decaying exotic particles with lifetime longer than $\sim 1$ sec. With a late-decaying particle in the early universe, predictions of the standard BBN scenario can be…
Big Bang Nucleosynthesis (BBN), as one of the earliest processes in the universe accessible to direct observation, offers a powerful and independent probe of the cosmic expansion history. With recent advances in both theory and observation,…
We present new Big Bang Nucleosynthesis (BBN) limits on the cosmic expansion rate or relativistic energy density, quantified via the number $N_\nu$ of equivalent neutrino species. We use the latest light element observations, neutron mean…
One of the three testaments in favor of the big bang theory is the prediction of the primordial elemental abundances in the big-bang nucleosynthesis (BBN). The Standard BBN is a parameter-free theory due to the precise knowledge of the…
We study effects of long-lived massive particles, which decay during the big-bang nucleosynthesis (BBN) epoch, on the primordial abundances of light elements. Compared to the previous studies, (i) the reaction rates of the standard BBN…
Taking into account effects of late energy injection, we examine big bang nucleosynthesis (BBN) constraints on axino dark matter scenarios with long-lived charged sleptons. We calculate 4-body slepton decays into the axino, a lepton, and a…