6,143 research outputs found
Quasi parton distribution functions at NNLO: flavor non-diagonal quark contributions
We present a next-to-next-to-leading order (NNLO) calculation of the quasi
parton distribution functions (Quasi-PDFs) in the large momentum effective
theory (LaMET). We focus on the flavor non-diagonal quark-quark channel and
demonstrate the LaMET factorization at the NNLO accuracy in the modified
minimal subtraction scheme. The matching coefficient between the quasi-PDF and
the light-cone PDF is derived. This provides a first step towards a complete
NNLO analysis of quasi-PDFs and to better understand the nucleon structures
from the first principle of QCD.Comment: 10 pages, 3 figures; v2: accepted for publication in Physical Review
D as a rapid communicatio
Generalized Hofstadter model on a cubic optical lattice: From nodal bands to the three-dimensional quantum Hall effect
We propose that a tunable generalized three-dimensional Hofstadter
Hamiltonian can be realized by engineering the Raman-assisted hopping of
ultracold atoms in a cubic optical lattice. The Hamiltonian describes a
periodic lattice system under artificial magnetic fluxes in three dimensions.
For certain hopping configurations, the bulk bands can have Weyl points and
nodal loops, respectively, allowing the study of both the two nodal semimetal
states within this system. Furthermore, we illustrate that with proper rational
fluxes and hopping parameters, the system can exhibit the three-dimensional
quantum Hall effect when the Fermi level lies in the band gaps, which is
topologically characterized by one or two nonzero Chern numbers. Our proposed
optical-lattice system provides a promising platform for exploring various
exotic topological phases in three dimensions.Comment: 10 pages, 5 figure
Five-dimensional vacuum Einstein spacetimes in C-metric like coordinates
A 5-dimensional Einstein spacetime with (non)vanishing cosmological constant
is analyzed in detail. The metric is in close analogy with the 4-dimensional
massless uncharged C-metric in many aspects. The coordinate system, horizons
and causal structures, relations to standard de Sitter, anti de Sitter and
Minkowski vacua are investigated. After a boost and Kaluza-Klein reduction, we
get an exact solution of 4-dimensional Einstein-Maxwell-Liouville theory which
reduces to a solution to Einstein-Liouville theory in the limit of zero boost
velocity and to that of Einstein-Maxwell-diliton theory in the case of zero
cosmological constant.Comment: 18 pages, 3 figures. Minor modifications, version appeared in Mod.
Phys. Lett.
Josephson dynamics of a spin-orbit coupled Bose-Einstein condensate in a double well potential
We investigate the quantum dynamics of an experimentally realized spin-orbit
coupled Bose-Einstein condensate in a double well potential. The spin-orbit
coupling can significantly enhance the atomic inter-well tunneling. We find the
coexistence of internal and external Josephson effects in the system, which are
moreover inherently coupled in a complicated form even in the absence of
interatomic interactions. Moreover, we show that the spin-dependent tunneling
between two wells can induce a net atomic spin current referred as spin
Josephson effects. Such novel spin Josephson effects can be observable for
realistically experimental conditions.Comment: 8 page
Infrared structures of scattering on self-dual radiative backgrounds
The scattering of gluons and gravitons in trivial backgrounds is endowed with
many surprising infrared features which have interesting conformal
interpretations on the two-dimensional celestial sphere. However, the fate of
these structures in more general asymptotically flat backgrounds is far from
clear. In this paper, we consider holomorphic infrared structures in the
presence of non-perturbative, self-dual background gauge and gravitational
fields which are determined by freely specified radiative data. We make use of
explicit formulae for tree-level gluon and graviton scattering in these
self-dual radiative backgrounds, as well as chiral twistor sigma model
descriptions of the classical dynamics. Remarkably, we find that the leading
holomorphic part of tree-level collinear splitting functions -- or celestial
OPEs -- and infinite-dimensional chiral soft algebras are undeformed by the
background. We also compute all-order holomorphic celestial OPEs in the MHV
sectors of gauge theory and gravity.Comment: 36+10 pages, no figure
- …