8,808 research outputs found
N*(1535) electroproduction at high Q2
A covariant spectator quark model is applied to study the gamma N -> N*(1535)
reaction in the large Q2 region. Starting from the relation between the nucleon
and N*(1535) systems, the N*(1535) valence quark wave function is determined
without the addition of any parameters. The model is then used to calculate the
gamma N -> N*(1535) transition form factors. A very interesting, useful
relation between the A12 and S12 helicity amplitudes for Q2 > GeV^2, is also
derived.Comment: Contribution to the proceedings of the 8th International Workshop on
the Physics of Excited Nucleons (NSTAR2011), Jefferson Lab, Newport News, VA,
USA, May 17-20, 201
Evaluation of a collaborative photography workshop using the iPad 2 as an accessible technology for participants who are blind, visually impaired and sighted working collaboratively
A workshop using iPads to train photographers who are blind, visually impaired and sighted is evaluated using a model of inclusive technical capital. It was hypothesized that all participants would find iPad apps accessible. It was found that iPads were good introductory devices, but experienced participants who are blind and sighted still preferred specialized cameras
The continuum limit of the quark mass step scaling function in quenched lattice QCD
The renormalisation group running of the quark mass is determined
non-perturbatively for a large range of scales, by computing the step scaling
function in the Schroedinger Functional formalism of quenched lattice QCD both
with and without O(a) improvement. A one-loop perturbative calculation of the
discretisation effects has been carried out for both the Wilson and the
Clover-improved actions and for a large number of lattice resolutions. The
non-perturbative computation yields continuum results which are regularisation
independent, thus providing convincing evidence for the uniqueness of the
continuum limit. As a byproduct, the ratio of the renormalisation group
invariant quark mass to the quark mass, renormalised at a hadronic scale, is
obtained with very high accuracy.Comment: 23 pages, 3 figures; minor changes, references adde
Berry curvature and Hall viscosities in an anisotropic Dirac semimetal
We investigate parity-odd nondissipative transport in an anisotropic Dirac semimetal in two spatial dimensions. The analysis is relevant for interacting electronic systems with merging Dirac points at charge neutrality. For such systems the dispersion relation is relativistic in one direction and nonrelativistic in the other. We give a proposal of how to calculate the Berry curvature for this system and use it to derive more than one odd viscosities, in contrast to rotationally invariant systems. We observe that in such a model the odd part of viscosity tensor is parametrized by two independent transport coefficients and one that is identically zero
High U(1) charges in type IIB models and their F-theory lift
We construct models with U(1) gauge group and matter with charges up to 6, in the context of type IIB compactifications. We show explicitly that models with charges up to 4 can be derived from corresponding models in F-theory by applying the Sen weak coupling limit. We derive which type IIB models should be the limit of charge 5 and 6 F-theory models. Explicit six dimensional type IIB models with maximal charge 5 and 6 are constructed on an algebraic K3 surface that is the double cover of \u2102\u2119 2 . By using type IIB results we are also able to rediscover the F-theory charge 4 model in a straightforward way
Space-Dependent Symmetries and Fractons
There has been a surge of interest in effective non-Lorentzian theories of excitations with restricted mobility, known as fractons. Examples include defects in elastic materials, vortex lattices or spin liquids. In the effective theory novel coordinate-dependent symmetries emerge that shape the properties of fractons. In this review we will discuss these symmetries, cover the effective description of gapless fractons via elastic duality, and discuss their hydrodynamics
- …