Particle theory

Abstract:

Cold dark matter particles with an intrinsic matter-antimatter asymmetry do not annihilate after gravitational capture by the Sun and can affect its interior structure. The rate of capture is exponentially enhanced when such particles have self-interactions of the right order to explain structure formation on galactic scales. A "dark baryon" of mass 5 GeV is a natural candidate and has the required relic abundance if its asymmetry is similar to that of ordinary baryons. We show that such particles can solve the "solar composition problem." The predicted small decrease in the low energy neutrino fluxes may be measurable by the Borexino and SNO+ experiments.

Abstract:

We present a practical, algebraic method for efficiently calculating the Yukawa couplings of a large class of heterotic compactifications on Calabi-Yau three-folds with non-standard embeddings. Our methodology covers all of, though is not restricted to, the recently classified positive monads over favourable complete intersection Calabi-Yau three-folds. Since the algorithm is based on manipulating polynomials it can be easily implemented on a computer. This makes the automated investigation of Yukawa couplings for large classes of smooth heterotic compactifications a viable possibility. © 2010 Springer-Verlag.

Abstract:

We consider a hidden-valley gauge sector, G, with strong coupling scale Lambda~TeV and CP-violating topological parameter, theta, as well as a new axion degree of freedom which adjusts theta to near zero in the current universe. If the G-sector couples to the Standard Model via weak-scale states charged under both, then in the early universe it is possible for the CP-violation due to theta (which has not yet been adjusted to zero by the hidden axion) to feed in to the SM and drive efficient baryogenesis during the electroweak (EW) phase transition, independent of the effectively small amount of CP violation present in the SM itself. While current constraints on both the new axion and charged states are easily satisfied, we argue that the LHC can investigate the vast majority of parameter space where EW-baryogenesis is efficiently assisted, while the hidden axion should comprise a significant fraction of the dark matter density. In the supersymmetric version, the ``messenger'' matter communicating between the SM- and G-sectors naturally solves the little hierarchy problem of the MSSM. The connection of the hidden scale and masses of the ``quirk''-like messengers to the EW scale via the assisted electroweak baryogenesis mechanism provides a reason for such new hidden valley physics to lie at the weak scale.