5,247 research outputs found
Electronic properties of graphene multilayers
We study the effects of disorder in the electronic properties of graphene
multilayers, with special focus on the bilayer and the infinite stack. At low
energies and long wavelengths, the electronic self-energies and density of
states exhibit behavior with divergences near half-filling. As a consequence,
the spectral functions and conductivities do not follow Landau's Fermi liquid
theory. In particular, we show that the quasiparticle decay rate has a minimum
as a function of energy, there is a universal minimum value for the in-plane
conductivity of order e^2/h per plane and, unexpectedly, the c-axis
conductivity is enhanced by disorder at low doping, leading to an enormous
conductivity anisotropy at low temperatures.Comment: 4 pages, 4 figure. Reference to exciting new ARPES results on
graphite added (we thank A. Lanzara for sharing the paper prior to its
publication
Electromagnetic Corrections in Partially Quenched Chiral Perturbation Theory
We introduce photons in Partially Quenched Chiral Perturbation Theory and
calculate the resulting electromagnetic loop-corrections at NLO for the charged
meson masses and decay constants. We also present a numerical analysis to
indicate the size of the different corrections. We show that several
phenomenologically relevant quantities can be calculated consistently with
photons which couple only to the valence quarks, allowing the use of gluon
configurations produced without dynamical photons.Comment: 11 page
On the Entropy of a Family of Random Substitutions
The generalised random Fibonacci chain is a stochastic extension of the
classical Fibonacci substitution and is defined as the rule mapping and with probability , where with
, and where the random rule is applied each time it acts on
a 1. We show that the topological entropy of this object is given by the growth
rate of the set of inflated generalised random Fibonacci words.Comment: A more appropriate tile and minor misprints corrected, compared to
the previous versio
Transmission through a biased graphene bilayer barrier
We study the electronic transmission through a graphene bilayer in the
presence of an applied bias between layers. We consider different geometries
involving interfaces between both a monolayer and a bilayer and between two
bilayers. The applied bias opens a sizable gap in the spectrum inside the
bilayer barrier region, thus leading to large changes in the transmission
probability and electronic conductance that are controlled by the applied bias.Comment: 10 pages, 8 figures, extended versio
Persistent currents through a quantum impurity: Protection through integrability
We consider an integrable model of a one-dimensional mesoscopic ring with the
conduction electrons coupled by a spin exchange to a magnetic impurity. A
symmetry analysis based on a Bethe Ansatz solution of the model reveals that
the current is insensitive to the presence of the impurity. We argue that this
is true for any integrable impurity-electron interaction, independent of choice
of physical parameters or couplings. We propose a simple physical picture of
how the persistent current gets protected by integrability.Comment: 5 pages, minor update
Evolution from a nodeless gap to d(x2-y2) form in underdoped La(2-x)SrxCuO4
Using angle-resolved photoemission (ARPES), it is revealed that the
low-energy electronic excitation spectra of highly underdoped superconducting
and non-superconducting La(2-x)SrxCuO4 cuprates are gapped along the entire
underlying Fermi surface at low temperatures. We show how the gap function
evolves to a d(x2-y2) form as increasing temperature or doping, consistent with
the vast majority of ARPES studies of cuprates. Our results provide essential
information for uncovering the symmetry of the order parameter(s) in strongly
underdoped cuprates, which is a prerequisite for understanding the pairing
mechanism and how superconductivity emerges from a Mott insulator.Comment: 5 pages, 4 figure
A Theory of Rent Seeking with Informational Foundations
I develop a model of rent seeking with informational foundations and an arbitrary number of rent seekers, and I compare the results with Tullockâs (1980) classic model where the influence activities are âblackboxed.â Given the microfoundations, the welfare consequences of rent seeking can be studied. In particular, I show that competition among rent seekers can be socially beneficial, since the additional information that the decision maker gets access to makes the increase in rent-seeking expenditures worthwhile. However, the analysis also highlights a logic that, under natural parameter assumptions, makes the rent seekers spend more resources on rent seeking than is in societyâs interest, which is consistent with the spirit of the rent-seeking literature
CP^n, or, entanglement illustrated
We show that many topological and geometrical properties of complex
projective space can be understood just by looking at a suitably constructed
picture. The idea is to view CP^n as a set of flat tori parametrized by the
positive octant of a round sphere. We pay particular attention to submanifolds
of constant entanglement in CP^3 and give a few new results concerning them.Comment: 28 pages, 9 figure
Penambahan Sari Jeruk Nipis terhadap Karakteristik Sirup Labu Siam
The purpose of this research was to obtain the ratio of chayote extracts and lime extractsin the manufactured of syrup. This research used Complete Randomized Design (CRD) with four treatments and four replication which followed by Duncan's New Multiple Range Test (DNMRT) at level 5%. The treatments in this research included LS0(ratio of chayote extracts and lime extracts 100 : 0), LS1 (ratio chayote extracts and lime extracts 95 : 05), LS2 (ratio chayote extracts and lime extracts 90 : 10), LS3 (chayote extracts and lime extracts 85 : 15). The results of analysis showed that the ratio of chayote extracts and lime extracts significantly effect on acidity (pH), viscosity, total dissolve, sucrose content and organoleptic value (colour, flavour, taste, consistency and overall acceptability). The bestsyrup was LS3 with acidity (pH) 4,45, viscosity 528,33cP, total dissolved 71,03 brix, sucrose content 65,44%. Overall preferred by the panelists with description the colour of rather murky, not falvorful chayote and falvorful lime, sweet taste little acidic and condensed
Determination of spin and parity of D(s)â mesons
The spin and parity of the charmed mesons Dsâ+, Dâ0 and Dâ+ are determined for the first time to be JP=1â with significances greater than 10Ï over other hypotheses of 2+ and 3â, using an e+eâ collision data sample with an integrated luminosity of 3.19 fbâ1 collected by the BESIII detector at a center-of-mass energy of 4.178 GeV. Different spin-parity hypotheses are tested via a helicity amplitude analysis of the processes e+eââDsâ+Dsâ, Dâ0D0 and Dâ+Dâ, with Dsâ+âDs+Îł, Dâ0âD0Ï0, and Dâ+âD+Ï0. The results confirm the quark model predictions.</p
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