10,467 research outputs found
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 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 asymmetry in a
scenario of a concrete flavor model realization.Comment: 25 pages, 7 figures; version 2: A few clarifications added. Version
matches publication in JHE
Spin Chain Hamiltonians with Affine symmetry
We construct the family of spin chain Hamiltonians, which have affine
guantum group symmetry. Their eigenvalues coincides with the eigenvalues of the
usual spin chain Hamiltonians which have non-affine quantum group
symmetry, but have the degeneracy of levels, corresponding to affine .
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
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