Baryogenesis from Symmetry Principle

In this work, a formalism based on symmetry which allows one to express asymmetries of all the particles in terms of conserved charges is developed. The manifestation of symmetry allows one to easily determine the viability of a baryogenesis scenario and also to identity the different roles played by the symmetry. This formalism is then applied to the standard model and its supersymmetric extension, which constitute two important foundations for constructing models of baryogenesis.Comment: 15 pages, 1 figure, 3 tables. Slight modifications to match the published versio

The EDGES signal: An imprint from the mirror world?

Recent results from the Experiment to Detect the Global Epoch of Reionization Signature (EDGES) show an anomalous spectral feature at redshifts $z\sim 15-20$ in its 21-cm absorption signal. This deviation from cosmological predictions can be understood as a consequence of physics that either lower the hydrogen spin temperature or increases the radiation temperature through the injection of soft photons in the bath. In the latter case, standard model neutrino decays $\nu_i \to \nu_j\,\gamma$ induced by effective magnetic and electric transition moments ($\mu_\text{eff}$) are precluded by the tight astrophysical constraints on $\mu_\text{eff}$. We show that if mirror neutrinos are present in the bath at early times, an analogous mechanism in the mirror sector can lead to a population of mirror photons that are then "processed" into visible photons through resonant conversion, thus accounting for the EDGES signal. We point out that the mechanism can work for mirror neutrinos which are either heavier than or degenerate with the standard model (SM) neutrinos, a scenario naturally realized in mirror twin Higgs models.Comment: 8 pages, 2 figure

Analytic Neutrino Oscillation Probabilities

In the work, we derive exact analytic expressions for $(3+N)$-flavor neutrino oscillation probabilities in an arbitrary matter potential in term of matrix elements and eigenvalues of the Hamiltonian. With radical solutions for a quartic polynomial, we obtain the first exact analytic oscillation probabilities for the $(3+1)$-flavor scenario in an arbitrary matter potential. With the analytic expressions, we demonstrate that nonunitary and nonstandard neutrino interaction scenarios are physically distinct: they satisfy different identities and can in principle be distinguished experimentally. The analytic expressions are implemented in a public code NuProbe, a tool for probing new physics through neutrino oscillations.Comment: Many new references added, especially on (3+1) analytic solutions (ours are clearly not the first). NuProbe code available at https://github.com/shengfong/nuprob

Non-unitary evolution of neutrinos in matter and the leptonic unitarity test

We present a comprehensive study of the three-active plus $N$ sterile neutrino model as a framework for constraining leptonic unitarity violation induced at energy scales much lower than the electroweak scale. We formulate a perturbation theory with expansion in small unitarity violating matrix element $W$ while keeping (non-$W$ suppressed) matter effect to all orders. We show that under the same condition of sterile state masses $0.1\, \text{eV}^2 \lesssim m^2_{J} \lesssim (1-10)\, \text{GeV}^2$ as in vacuum, assuming typical accelerator based long-baseline neutrino oscillation experiment, one can derive a very simple form of the oscillation probability which consists only of zeroth-order terms with the unique exception of probability leaking term $\mathcal{C}_{\alpha \beta}$ of $\mathcal{O} (W^4)$. We argue, based on our explicit computation to fourth-order in $W$, that all the other terms are negligibly small after taking into account the suppression due to the mass condition for sterile states, rendering the oscillation probability {\em sterile-sector model independent}. Then, we identify a limited energy region in which this suppression is evaded and the effects of order $W^2$ corrections may be observable. Its detection would provide another way, in addition to detecting $\mathcal{C}_{\alpha \beta}$, to distinguish between low-scale and high-scale unitarity violation. We also solve analytically the zeroth-order system in matter with uniform density to provide a basis for numerical evaluation of non-unitary neutrino evolution.Comment: 35 content pages + 12 appendix pages, 4 figures; Several clarifying modifications to match the published versio