11,664 research outputs found
Spatially resolved spectroscopy of monolayer graphene on SiO2
We have carried out scanning tunneling spectroscopy measurements on
exfoliated monolayer graphene on SiO to probe the correlation between its
electronic and structural properties. Maps of the local density of states are
characterized by electron and hole puddles that arise due to long range
intravalley scattering from intrinsic ripples in graphene and random charged
impurities. At low energy, we observe short range intervalley scattering which
we attribute to lattice defects. Our results demonstrate that the electronic
properties of graphene are influenced by intrinsic ripples, defects and the
underlying SiO substrate.Comment: 6 pages, 7 figures, extended versio
On the magnetic equation of state in (2+1)-flavor QCD
A first study of critical behavior in the vicinity of the chiral phase
transition of (2+1)-flavor QCD is presented. We analyze the quark mass and
volume dependence of the chiral condensate and chiral susceptibilities in QCD
with two degenerate light quark masses and a strange quark. The strange quark
mass (m_s) is chosen close to its physical value; the two degenerate light
quark masses (m_l) are varied in a wide range 1/80 \le m_l/m_s \le 2/5, where
the smallest light quark mass value corresponds to a pseudo-scalar Goldstone
mass of about 75 MeV. All calculations are performed with staggered fermions on
lattices with temporal extent Nt=4. We show that numerical results are
consistent with O(N) scaling in the chiral limit. We find that in the region of
physical light quark mass values, m_l/m_s \simeq 1/20, the temperature and
quark mass dependence of the chiral condensate is already dominated by
universal properties of QCD that are encoded in the scaling function for the
chiral order parameter, the magnetic equation of state. We also provide
evidence for the influence of thermal fluctuations of Goldstone modes on the
chiral condensate at finite temperature. At temperatures below, but close to
the chiral phase transition at vanishing quark mass, this leads to a
characteristic dependence of the light quark chiral condensate on the square
root of the light quark mass.Comment: 18 pages, 18 EPS-file
Mobile Edge Computing for 5G Internet of Things
This is the author accepted manuscript. The final version is available from CRC Press via the link in this recor
Relativistic effects in a mildly recycled pulsar binary: PSR J1952+2630
We report the results of timing observations of PSR J1952+2630, a 20.7 ms
pulsar in orbit with a massive white dwarf companion. With the increased timing
baseline, we obtain improved estimates for astrometric, spin, and binary
parameters for this system. We get an improvement of an order of magnitude on
the proper motion, and, for the first time, we detect three post-Keplerian
parameters in this system: the advance of periastron, the orbital decay, and
the Shapiro delay. We constrain the pulsar mass to 1.20 and the mass of its companion to 0.97. The current value of is consistent with GR
expectation for the masses obtained using and . The excess
represents a limit on the emission of dipolar GWs from this system. This
results in a limit on the difference in effective scalar couplings for the
pulsar and companion (predicted by scalar-tensor theories of gravity; STTs) of
, which does not yield a
competitive test for STTs. However, our simulations of future campaigns of this
system show that by 2032, the precision of and
will allow for much more precise masses and much tighter constraints on the
orbital decay contribution from dipolar GWs, resulting in . We also present the constraints this
system will place on the parameters of DEF gravity by
2032. They are comparable to those of PSR J1738+0333. Unlike PSR J1738+0333,
PSR J1952+2630 will not be limited in its mass measurement and has the
potential to place even more restrictive limits on DEF gravity in the future.
Further improvements to this test will likely be limited by uncertainties in
the kinematic contributions to due to lack of precise
distance measurements.Comment: 14 pages, 9 figures, 4 tables. Accepted for publication in Astronomy
& Astrophysic
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