Yukawa Phase Research Articles

Bridge functions of classical one-component plasmas.

In a recent paper, Lucco Castello etal. [arXiv:2107.03537] performed systematic extractions of classical one-component plasma bridge functions from molecular dynamics simulations and provided an accurate parametrization that was incorporated in their isomorph-based empirically modified hypernetted chain approach for Yukawa one-component plasmas. Here the extraction technique and parametrization strategy are described in detail, while the deficiencies of earlier efforts are discussed. The structural and thermodynamic predictions of the updated version of the integral equationtheory approach are compared with extensive available simulation results revealing a truly unprecedented level of accuracy in the entire dense liquid region of the Yukawa phase diagram.

Leptogenesis and gravity: Baryon asymmetry without decays

A popular class of theories attributes the matter-antimatter asymmetry of the Universe to CP-violating decays of super-heavy BSM particles in the Early Universe. Recently, we discovered a new source of leptogenesis in these models, namely that the same Yukawa phases which provide the CP violation for decays, combined with curved-spacetime loop effects, lead to an entirely new gravitational mechanism for generating an asymmetry, driven by the expansion of the Universe and independent of the departure of the heavy particles from equilibrium. In this Letter, we build on previous work by analysing the full Boltzmann equation, exploring the full parameter space of the theory and studying the time-evolution of the asymmetry. Remarkably, we find regions of parameter space where decays play no part at all, and where the baryon asymmetry of the Universe is determined solely by gravitational effects.

Ionic transport in high-energy-density matter.

Ionic transport coefficients for dense plasmas have been numerically computed using an effective Boltzmann approach. We have developed a simplified effective potential approach that yields accurate fits for all of the relevant cross sections and collision integrals. Our results have been validated with molecular-dynamics simulations for self-diffusion, interdiffusion, viscosity, and thermal conductivity. Molecular dynamics has also been used to examine the underlying assumptions of the Boltzmann approach through a categorization of behaviors of the velocity autocorrelation function in the Yukawa phase diagram. Using a velocity-dependent screening model, we examine the role of dynamical screening in transport. Implications of these results for Coulomb logarithm approaches are discussed.

Leptogenesis in a seesaw model with Fritzsch-type lepton mass matrices

We investigate how the baryon asymmetry of our Universe via leptogenesis can be achieved within the framework of the seesaw model with Fritzsch-type lepton mass matrices proposed by Fukugita et al. We study the cases with $CP$-violating phases in charged-lepton Yukawa matrix, however, with and without Dirac neutrino Yukawa phases. We consider both flavor-independent and flavor-dependent leptogenesis, and demonstrate how they lead to different amounts of lepton asymmetries in detail. In particular, it is shown that flavor-dependent leptogenesis in this model can be achieved only for very tiny or zero values of $CP$ phases in Dirac neutrino Yukawa matrix at the grand unified theory scale. In addition to the $CP$ phases, for successful leptogenesis in the model it is required that the degeneracy of the heavy Majorana neutrino mass spectrum should be broken and we also show that the breakdown of the degeneracy can be radiatively induced.

The next Yukawa phase of QCD at RHIC

QCD predicts the existence of a new partonic Yukawa phase above a critical temperature $T_c\sim 150$ MeV. I review some of the key observables which will be used in heavy ion reactions to search for this new phase at RHIC. Systematics of collective observables ($N_{ch},E_\perp)$, flow patterns, meson interferometry, jet quenching, and $J/\psi$ suppression are discussed. This talk is updated with the first data from RHIC.

Effects of the right-handed neutrinos on ΔS = 2 and ΔB = 2 processes in supersymmetric SU(5) model

We discuss an extra source of CP and flavor violations in supersymmetric SU(5) grand unified model with the right-handed neutrinos. In such a model, the right-handed down-type squarks \tilde{d}_R interact with the right-handed neutrinos above the GUT scale, and the renormalization group effect can generate sizable off-diagonal elements in the mass matrix of \tilde{d}_R. Because of new Yukawa phases which exist in the SU(5) model, these off-diagonal elements have, in general, large CP violating phases. The renormalization group induced off-diagonal elements affect the K and B decays. In particular, in this model, supersymmetric contribution to the \epsilon_K parameter can be as large as the currently measured experimental value, and hence the effect might be seen as an anomaly in the on-going test of the Cabibbo-Kobayashi-Maskawa triangle.

Searching for the Next Yukawa Phase of QCD

QCD predicts that the interactions between quarks and gluons change from a confining to a screened Yukawa form above a critical temperature Tc ∼ 150 MeV. In this talk, I review some of the key observables in heavy ion reactions which are being used to search for this new partonic Yukawa phase at SPS and RHIC. These include collective observables such as dE⊥/dydp⊥, meson interferometry, jet quenching, and J/ψ suppression.

Electric dipole moments from Yukawa phases in supersymmetric theories

We study quark and electron EDMs generated by Yukawa couplings in supersymmetric models with different gauge groups, using the EDM properties under flavour transformations. In the MSSM (or if soft terms are mediated below the unification scale) the one-loop contributions to the neutron EDM are smaller than in previous computations based on numerical methods, although increasing as tan 3 β. A neutron EDM close to the experimental limits can be generated in SU(5), if tan β is large, through the u-quark EDM d u , proportional to tan 4 β. This effect has to be taken into account also in SO(10) with large tan β, where d u is comparable to the d quark EDM, proportional to tan β.