37,689 research outputs found
Nuclear Modification to Parton Distribution Functions and Parton Saturation
We introduce a generalized definition of parton distribution functions (PDFs)
for a more consistent all-order treatment of power corrections. We present a
new set of modified DGLAP evolution equations for nuclear PDFs, and show that
the resummed -type of leading nuclear size enhanced power
corrections significantly slow down the growth of gluon density at small-.
We discuss the relation between the calculated power corrections and the
saturation phenomena.Comment: 4 pages, to appear in the proceedings of QM200
Electronic structure of YbB: Is it a Topological Insulator or not?
To resolve the controversial issue of the topological nature of the
electronic structure of YbB, we have made a combined study using density
functional theory (DFT) and angle resolved photoemission spectroscopy (ARPES).
Accurate determination of the low energy band topology in DFT requires the use
of modified Becke-Johnson exchange potential incorporating the spin-orbit
coupling and the on-site Coulomb interaction of Yb electrons as large
as 7 eV. We have double-checked the DFT result with the more precise GW band
calculation. ARPES is done with the non-polar (110) surface termination to
avoid band bending and quantum well confinement that have confused ARPES
spectra taken on the polar (001) surface termination. Thereby we show
definitively that YbB has a topologically trivial B 2-Yb 5
semiconductor band gap, and hence is a non-Kondo non-topological insulator
(TI). In agreement with theory, ARPES shows pure divalency for Yb and a -
band gap of 0.3 eV, which clearly rules out both of the previous scenarios of
- band inversion Kondo TI and - band inversion non-Kondo TI. We
have also examined the pressure-dependent electronic structure of YbB,
and found that the high pressure phase is not a Kondo TI but a
\emph{p}-\emph{d} overlap semimetal.Comment: The main text is 6 pages with 4 figures, and the supplementary
information contains 6 figures. 11 pages, 10 figures in total To be appeared
in Phys. Rev. Lett. (Online publication is around March 16 if no delays.
Structures of ultrathin copper nanotubes
We have performed atomistic simulations for helical multi-shell (HMS) Cu
nanowires and nanotubes. Our investigation on HMS Cu nanowires and nanotubes
has revealed some physical properties that were not dealt in previous works
that considered metal nanowires. As the diameter of HMS nanowires increased,
their cohesive energy per atom and optimum lattice constant decreased. As the
diameter of HMS nanotubes increases, their cohesive energy per atom decreased
but optimum lattice constant increased. Shell-shell or core-shell interactions
mainly affected on the lattice constant and the diameter of HMS nanowires or
nanotubes. This study showed that HMS nanotubes for materials of fcc metal
crystals can be maintained when forces exerted on atoms of inner shell of the
HMS nanotubes are zero or act on the direction of the outside.Comment: 16 pages, 1 table, 5 figure
Triple sign reversal of Hall effect in HgBa_{2}CaCu_{2}O_{6} thin films after heavy-ion irradiations
Triple sign reversal in the mixed-state Hall effect has been observed for the
first time in ion-irradiated HgBa_{2}CaCu_{2}O_{6} thin films. The negative dip
at the third sign reversal is more pronounced for higher fields, which is
opposite to the case of the first sign reversal near T_c in most high-T_c
superconductors. These observations can be explained by a recent prediction in
which the third sign reversal is attributed to the energy derivative of the
density of states and to a temperature-dependent function related to the
superconducting energy gap. These contributions prominently appear in cases
where the mean free path is significantly decreased, such as our case of
ion-irradiated thin films.Comment: 4 pages, 3 eps figures, submitted Phys. Rev. Let
Extracting CP violation and strong phase in D decays by using quantum correlations in psi(3770)-> D0\bar{D}0 -> (V1V2)(V3V4) and psi(3770)->D0\bar{D}0 -> (V1V2)(K pi)
The charm quark offers interesting opportunities to cross-check the mechanism
of CP violation precisely tested in the strange and beauty sectors. In this
paper, we exploit the angular and quantum correlations in the D\bar{D} pairs
produced through the decay of the psi(3770) resonance in a charm factory to
investigate CP-violation in two different ways. We build CP-violating
observables in psi(3770) -> D\bar{D} -> (V_1V_2)(V_3 V_4) to isolate specific
New Physics effects in the charm sector. We also consider the case of psi(3770)
-> D\bar{D} -> (V_1V_2)(K\pi) decays, which provide a new way to measure the
strong phase difference delta between Cabibbo-favored and doubly-Cabibbo
suppressed D decays required in the determination of the CKM angle gamma.
Neglecting the systematics, we give a first rough estimate of the sensitivities
of these measurements at BES-III with an integrated luminosity of 20 fb^-1 at
psi(3770) peak and at a future Super tau-charm factory with a luminosity of
10^35 cm^-2.s^-1.Comment: 13 pages
Noise acceptance of acoustic sequences for indoor soundscape in transport hubs
Noise acceptance is an aspect of indoor soundscape research. While staying or walking in a transport hub, sequential sounds form sequence sounds sessions, which are referred to as an acoustic sequence. The basic phenomenon and effects of acoustic sequences on acceptance evaluations have been explored. A total of 209 sections of 30 s acoustic units were extracted before performing acceptance evaluations. The acoustic units were divided into strong, medium, and weak levels, and compiled into 37 pieces of acoustic sequences, which were then subjected to four tests for acceptance evaluation: sound content, acceptance level, and effects of weak and strong acceptance units. One piece of an acoustic sequence consists of 20 acoustic units. The results show that all acoustic sequences exhibit “attenuation effects”—as for any acoustic unit that makes up the sequence, general acceptance decreases with time. The lower the acceptance, the faster the decay in score. High acceptance units have an “enhancement effect,” and the acceptance increases after a high acceptance unit. Low acceptance units have a “boost effect,” and the acceptance increases after a low-level acceptance. Both enhancement and boost effects could improve the acceptance evaluation of acoustic sequences and sound experiences in transport hubs
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