11,687 research outputs found
Effect of strong correlations on the high energy anomaly in hole- and electron-doped high-Tc superconductors
Recently, angle-resolved photoemission spectroscopy (ARPES) has been used to
highlight an anomalously large band renormalization at high binding energies in
cuprate superconductors: the high energy 'waterfall' or high energy anomaly
(HEA). This paper demonstrates, using a combination of new ARPES measurements
and quantum Monte Carlo simulations, that the HEA is not simply the by-product
of matrix element effects, but rather represents a cross-over from a
quasiparticle band at low binding energies near the Fermi level to valence
bands at higher binding energy, assumed to be of strong oxygen character, in
both hole- and electron-doped cuprates. While photoemission matrix elements
clearly play a role in changing the aesthetic appearance of the band
dispersion, i.e. the 'waterfall'-like behavior, they provide an inadequate
description for the physics that underlies the strong band renormalization
giving rise to the HEA. Model calculations of the single-band Hubbard
Hamiltonian showcase the role played by correlations in the formation of the
HEA and uncover significant differences in the HEA energy scale for hole- and
electron-doped cuprates. In addition, this approach properly captures the
transfer of spectral weight accompanying both hole and electron doping in a
correlated material and provides a unifying description of the HEA across both
sides of the cuprate phase diagram.Comment: Original: 4 pages, 4 figures; Replaced: changed and updated content,
12 pages, 6 figure
Energy Flows in Low-Entropy Complex Systems
Nature's many complex systems--physical, biological, and cultural--are
islands of low-entropy order within increasingly disordered seas of
surrounding, high-entropy chaos. Energy is a principal facilitator of the
rising complexity of all such systems in the expanding Universe, including
galaxies, stars, planets, life, society, and machines. A large amount of
empirical evidence--relating neither entropy nor information, rather
energy--suggests that an underlying simplicity guides the emergence and growth
of complexity among many known, highly varied systems in the
14-billion-year-old Universe, from big bang to humankind. Energy flows are as
centrally important to life and society as they are to stars and galaxies. In
particular, the quantity energy rate density--the rate of energy flow per unit
mass--can be used to explicate in a consistent, uniform, and unifying way a
huge collection of diverse complex systems observed throughout Nature.
Operationally, those systems able to utilize optimal amounts of energy tend to
survive and those that cannot are non-randomly eliminated.Comment: 12 pages, 2 figures, review paper for special issue on Recent
Advances in Non-Equilibrium Statistical Mechanics and its Application. arXiv
admin note: text overlap with arXiv:1406.273
Testing the dynamics of high energy scattering using vector meson production
I review work on diffractive vector meson production in photon-proton
collisions at high energy and large momentum transfer, accompanied by proton
dissociation and a large rapidity gap. This process provides a test of the high
energy scattering dynamics, but is also sensitive to the details of the
treatment of the vector meson vertex.
The emphasis is on the description of the process by a solution of the
non-forward BFKL equation, i.e. the equation describing the evolution of
scattering amplitudes in the high-energy limit of QCD. The formation of the
vector meson and the non-perturbative modeling needed is also briefly
discussed.Comment: 17 pages, 8 figures. Brief review to appear in Mod. Phys. Lett.
Maxwell's Theory of Solid Angle and the Construction of Knotted Fields
We provide a systematic description of the solid angle function as a means of
constructing a knotted field for any curve or link in . This is a
purely geometric construction in which all of the properties of the entire
knotted field derive from the geometry of the curve, and from projective and
spherical geometry. We emphasise a fundamental homotopy formula as unifying
different formulae for computing the solid angle. The solid angle induces a
natural framing of the curve, which we show is related to its writhe and use to
characterise the local structure in a neighborhood of the knot. Finally, we
discuss computational implementation of the formulae derived, with C code
provided, and give illustrations for how the solid angle may be used to give
explicit constructions of knotted scroll waves in excitable media and knotted
director fields around disclination lines in nematic liquid crystals.Comment: 20 pages, 9 figure
Fluxes in F-theory Compactifications on Genus-One Fibrations
We initiate the construction of gauge fluxes in F-theory compactifications on
genus-one fibrations which only have a multi-section as opposed to a section.
F-theory on such spaces gives rise to discrete gauge symmetries in the
effective action. We generalize the transversality conditions on gauge fluxes
known for elliptic fibrations by taking into account the properties of the
available multi-section. We test these general conditions by constructing all
vertical gauge fluxes in a bisection model with gauge group SU(5) x Z2. The
non-abelian anomalies are shown to vanish. These flux solutions are dynamically
related to fluxes on a fibration with gauge group SU(5) x U(1) by a conifold
transition. Considerations of flux quantization reveal an arithmetic constraint
on certain intersection numbers on the base which must necessarily be satisfied
in a smooth geometry. Combined with the proposed transversality conditions on
the fluxes these conditions are shown to imply cancellation of the discrete Z2
gauge anomalies as required by general consistency considerations.Comment: 30 pages; v2: typos correcte
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