相关论文: Bounds on long-lived charged massive particles fro…
We present calculations showing how electron rest mass influences entropy flow, neutrino decoupling, and Big Bang Nucleosynthesis (BBN) in the early universe. To elucidate this physics and especially the sensitivity of BBN and related…
We re-examine the big bang nucleosynthesis (BBN) bounds on the mixing of neutrinos with sterile species. These bounds depend on the assumption that the relic neutrino asymmetry $L_{\nu}$ is very small. We show that for $L_{\nu}$ large…
We present a brief review of Big Bang Nucleosynthesis (BBN). We discuss theoretical and observational uncertainties in deuterium and helium-4 primordial abundances and their implications for the determination of important cosmological…
Big bang nucleosynthesis in a modified gravity model of $f(R)\propto R^n$ is investigated. The only free parameter of the model is a power-law index $n$. We find cosmological solutions in a parameter region of $1< n \leq (4+\sqrt{6})/5$. We…
The cosmic microwave background (CMB) spectrum provides tight constraints on the thermal history of the universe up to $z \sim 2\times 10^6$. At higher redshifts thermalization processes become very efficient so that even large energy…
We propose a correction of the standard Big Bang nucleosynthesis (BBN) scenario to resolve the primordial lithium problem by considering a possibility that the primordial plasma can deviate from the ideal state. In the standard BBN, the…
The last parameter of big-bang nucleosynthesis, the baryon density, is being pinned down by measurements of the deuterium abundance in high-redshift hydrogen clouds. When it is determined, it will fix the primeval light-element abundances.…
We study three-flavor neutrino oscillations in the early universe in the presence of neutrino chemical potentials. We take into account all effects from the background medium, i.e. collisional damping, the refractive effects from charged…
We examine big bang nucleosynthesis (BBN) in models with a time-varying gravitational constant $G$, when this time variation is rapid on the scale of the expansion rate $H$, i.e, $\dot G/G \gg H$. Such models can arise naturally in the…
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…
Big Bang Nucleosynthesis (BBN) is the synthesis of the light nuclei, Deuterium, He3, He4 and Li7, during the first few minutes of the universe. This review concentrates on recent improvements in the measurement of the primordial (after BBN,…
We evaluate abundance anomalies generated in patches of the universe where the baryon-to-photon ratio was locally enhanced by possibly many orders of magnitude in the range $\eta = 10^{-10} - 10^{-1}$. Our study is motivated by the possible…
We identify reactions which destroy 7Be and 7Li during big bang nucleosynthesis (BBN) in the scenario of BBN catalyzed by a long-lived sub-strongly interacting massive particle (sub-SIMP or X particle). The destruction associated with non…
Following a brief introduction to early Universe cosmology, the current of status of big bang nucleosynthesis is reviewed and the concordance between theory and observation is examined in detail. The abundances of He4 and Li7 determine the…
The hot and dense early Universe combined with the promise of high-precision cosmological observations provide an intriguing laboratory for Beyond Standard Model (BSM) physics. We simulate the early Universe to examine the effects of the…
Based on a scenario of the inhomogeneous big-bang nucleosynthesis (IBBN), we investigate the detailed nucleosynthesis that includes the production of heavy elements beyond Li-7. From the observational constraints on light elements of He4…
Recently, the EMPRESS collaboration has included new data in the extraction of the primordial $^4$He abundance from Big Bang Nucleosynthesis (BBN), resulting in a determination that differs from the previous value and from theoretical…
In big bang nucleosynthesis (BBN), the light matter abundance is dictated by the neutron-to-proton ($n/p$) ratio which is controlled by the standard weak processes in the early universe. Here, we study the effect of an extra particle…
We improve Standard Big Bang Nucleosynthesis (SBBN) calculations taking into account new nuclear physics analyses (Descouvemont et al. 2003). Using a Monte-Carlo technique, we calculate the abundances of light nuclei versus the baryon to…
The $^6$Li abundance observed in metal poor halo stars appears to exhibit a plateau as a function of metallicity similar to that for $^7$Li, suggesting a big bang origin. However, the inferred primordial abundance of $^6$Li is $\sim$1000…