7,696 research outputs found
The lollipop graph is determined by its spectrum
An even (resp. odd) lollipop is the coalescence of a cycle of even (resp.
odd) length and a path with pendant vertex as distinguished vertex. It is known
that the odd lollipop is determined by its spectrum and the question is asked
by W. Haemers, X. Liu and Y. Zhang for the even lollipop. We revisit the proof
for odd lollipop, generalize it for even lollipop and therefore answer the
question. Our proof is essentially based on a method of counting closed walks
A combinatorial proof of the Rogers-Ramanujan and Schur identities
We give a combinatorial proof of the first Rogers-Ramanujan identity by using
two symmetries of a new generalization of Dyson's rank. These symmetries are
established by direct bijections.Comment: 12 pages, 5 figures; incorporated referee suggestions, simplified
definition of (k,m)-rank, to appear in JCT(A
Heat Capacity of the Pressure-induced Superconductivity in Itinerant Ferromagnet UGe
Recently co-existence of the ferromagnetism and superconductivity was
reported in the high-pressure region (1.0-1.6 GPa) in UGe. We performed the
heat capacity measurement on UGe under high pressure. At 1.13 GPa, we found
a peak corresponding to the superconducting transition. The superconducting
temperature and are 0.6 K and 0.25,
respectively. The superconducting transition was also confirmed by the
appearance of the Meissner effect in the {\it ac} susceptibility. From these
results, we confirm a bulk nature of the superconductivity in UGe. The
value of ( 95 mJ/moleK) just above at 1.15 GPa is as
much as 3 times larger than that at ambient pressure, which indicates a large
mass enhancement of quasiparticles under high pressure.Comment: submitted to the International Conference on Strongly Correlated
Electron Systems 200
From bare interactions, low--energy constants and unitary gas to nuclear density functionals without free parameters: application to neutron matter
We further progress along the line of Ref. [Phys. Rev. {\bf A 94}, 043614
(2016)] where a functional for Fermi systems with anomalously large -wave
scattering length was proposed that has no free parameters. The
functional is designed to correctly reproduce the unitary limit in Fermi gases
together with the leading-order contributions in the s- and p-wave channels at
low density. The functional is shown to be predictive up to densities
fm that is much higher densities compared to the Lee-Yang
functional, valid for fm. The form of the functional
retained in this work is further motivated. It is shown that the new functional
corresponds to an expansion of the energy in and to all
orders, where is the effective range and is the Fermi momentum. One
conclusion from the present work is that, except in the extremely low--density
regime, nuclear systems can be treated perturbatively in with
respect to the unitary limit. Starting from the functional, we introduce
density--dependent scales and show that scales associated to the bare
interaction are strongly renormalized by medium effects. As a consequence, some
of the scales at play around saturation are dominated by the unitary gas
properties and not directly to low-energy constants. For instance, we show that
the scale in the s-wave channel around saturation is proportional to the
so-called Bertsch parameter and becomes independent of . We also
point out that these scales are of the same order of magnitude than those
empirically obtained in the Skyrme energy density functional. We finally
propose a slight modification of the functional such that it becomes accurate
up to the saturation density fm
Comentarios, preguntas sobre colonización y extractivismo
Fil: Boulet, Patrick.
Universidad Nacional de Cuyo. Facultad de Ciencias Políticas y Sociale
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