Implications of finite one-loop corrections for seesaw neutrino masses

In the standard seesaw model, finite corrections to the neutrino mass matrix arise from one-loop self-energy diagrams mediated by a heavy neutrino. We discuss the impact that these corrections may have on the different low-energy neutrino observables paying special attention to their dependence with the seesaw model parameters. It is shown that sizable deviations from the tri-bimaximal mixing pattern can be obtained when these corrections are taken into account.Comment: 4 pages, 3 figures. Prepared for the proceedings of the 12th International Conference on Topics in Astroparticle and Underground Physics (TAUP 2011), Munich, Germany, 5-9 September 201

Noncommutative Blowups of Elliptic Algebras

We develop a ring-theoretic approach for blowing up many noncommutative projective surfaces. Let T be an elliptic algebra (meaning that, for some central element g of degree 1, T/gT is a twisted homogeneous coordinate ring of an elliptic curve E at an infinite order automorphism). Given an effective divisor d on E whose degree is not too big, we construct a blowup T(d) of T at d and show that it is also an elliptic algebra. Consequently it has many good properties: for example, it is strongly noetherian, Auslander-Gorenstein, and has a balanced dualizing complex. We also show that the ideal structure of T(d) is quite rigid. Our results generalise those of the first author. In the companion paper "Classifying Orders in the Sklyanin Algebra", we apply our results to classify orders in (a Veronese subalgebra of) a generic cubic or quadratic Sklyanin algebra.Comment: 39 pages. Minor changes from previous version. The final publication is available from Springer via http://dx.doi.org/10.1007/s10468-014-9506-

Coexistence of vector chiral order and Tomonaga-Luttinger liquid in the frustrated three-leg spin tube in a magnetic field

The frustrated three-leg antiferromagnetic spin-1/2 tube with a weak interchain coupling in a magnetic field is investigated by means of Abelian bosonization techniques. It is clearly shown that a vector chiral order and a one-component Tomonaga-Luttinger liquid coexist in a wide magnetic-field region from a state with a small magnetization to a nearly saturated one. The chiral order is predicted to still survive in the intermediate plateau state. We further predict that (even) when the strength of one bond in the three rung couplings is decreased (increased), an Ising type quantum phase transition takes place and the chirality vanishes (no singular phenomena occur and the chiral order is maintained). Even without magnetic fields, the chiral order would also be present, if the spin tube possess easy-plane anisotropy.Comment: 6 pages, 4 figures, Revtex, published versio

Low-Energy Properties of Antiferromagnetic Spin-1/2 Heisenberg Ladders with an Odd Number of Legs

An effective low-energy description for multi-leg spin-1/2 Heisenberg ladders with an odd number of legs is proposed. Using a newly developed Monte Carlo loop algorithm and exact diagonalization techniques, the uniform and staggered magnetic susceptibility and the entropy are calculated for ladders with 1, 3, and 5 legs. These systems show a low-temperature scaling behavior similar to spin-1/2 chains with longer ranged unfrustrated exchange interactions. The spinon velocity does not change as the number of legs increases, but the energy scale parameter decreases markedly.Comment: 4 pages and 5 figure

Sustainable Development and Environmental Justice: Connecting Students to Global Issues

This pilot study will contribute to the literature surrounding study abroad using a new framework to gauge the effect travel has on knowledge of global issues. The United Nations created a list of sustainable development goals meant to rectify pressing issues in the United States and abroad. The goals have been separated into the categories of ending poverty, ensuring prosperity for all, and protection of the planet. Using them as the framework for a quantitative study, data were collected from college-level students around South Carolina on perceptions of global issues through a sustainable lens. The project has had two phases; results and implications of the recent phase will be discussed

The One Loop Effective Super-Potential and Non-Holomorphicity

We calculate the Kahlerian and the lowest order non-Kahlerian contributions to the one loop effective superpotential using super-Feynman graphs in the massless Wess-Zumino Model, the massive Wess-Zumino Model and N=1, U(1) gauge theory. We also calculate the Kahlerian term in Yang-Mills Theory for a general gauge group. Using this latter result we find the one loop Kahlerian contribution for N=2 Yang-Mills Theory in terms of N=1 superfields and we show that it can only come from non-holomorphic contributions to the N=2 effective potential.Comment: LaTeX, 10 pages, 7 figures, uses bezier.sty and ifthen.sty. First amendment. The results are extended to include the Kahlerian term for a general renormalisable N=1 supersymmetric theory, containing Wess-Zumino and Yang-Mills multiplets with a cubic superpotential. One reference has been changed and one has been added. Second amendment. One acknowledgment has been altered in the `note added in proof

Leptogenesis in the presence of exact flavor symmetries

In models with flavor symmetries in the leptonic sector leptogenesis can take place in a very different way compared to the standard leptogenesis scenario. We study the generation of a $B-L$ asymmetry in these kind of models in the flavor symmetric phase pointing out that successful leptogenesis requires (i) the right-handed neutrinos to lie in different representations of the flavor group; (ii) the flavons to be lighter at least that one of the right-handed neutrino representations. When these conditions are satisfied leptogenesis proceeds due to new contributions to the CP violating asymmetry and -depending on the specific model- in several stages. We demonstrate the validity of these arguments by studying in detail the generation of the $B-L$ asymmetry in a scenario of a concrete $A_4$ flavor model realization.Comment: 25 pages, 7 figures; version 2: A few clarifications added. Version matches publication in JHE

Spin Chain Hamiltonians with Affine UqgU_q g symmetry

We construct the family of spin chain Hamiltonians, which have affine $U_q g$ guantum group symmetry. Their eigenvalues coincides with the eigenvalues of the usual spin chain Hamiltonians which have non-affine $U_q g_0$ quantum group symmetry, but have the degeneracy of levels, corresponding to affine $U_q g$. The space of states of these chaines are formed by the tensor product of the fully reducible representations.Comment: 10 pages, LATE

A new species of \u3ci\u3ePhyllium\u3c/i\u3e (\u3ci\u3ePhyllium\u3c/i\u3e) Illiger (Phasmida: Phylliidae) from Yap Island, Micronesia, representing a range expansion for the family

A new species of leaf insect from the celebicum species group, Phyllium (Phyllium) yapicum Cumming and Teemsma, new species (Phasmida: Phylliidae), is described from a female specimen from the California Academy of Sciences collection, United States. This new species is the first recorded species of Phylliidae from the country of Micronesia and represents a notable range expansion for the family. With Phyllium (Phyllium) yapicum Cumming and Teemsma, new species, currently only known from a female holotype; a key to females is included for the celebicum species group