6,110 research outputs found
Observational constraints on the types of cosmic strings
This paper is aimed at setting observational limits to the number of cosmic
strings (Nambu-Goto, Abelian-Higgs, semilocal) and other topological defects
(textures). Radio maps of CMB anisotropy, provided by the space mission Planck
for various frequencies, were filtered and then processed by the method of
convolution with modified Haar functions (MHF) to search for cosmic string
candidates. This method was designed to search for solitary strings, without
additional assumptions about the presence of networks of such objects. The
sensitivity of the MHF method is in a background of
. The comparison of these with previously known
results on search string network shows that strings can only be semilocal in an
amount of , with the upper restriction on individual strings tension
(linear density) of . The texture model is
also legal. There are no strings with . However,
comparison with the data for the search of non-Gaussian signals shows that the
presence of several (up to 3) of Nambu-Goto strings is also possible. For
the MHF method is ineffective because of
unverifiable spurious string candidates. Thus the existence of strings with
tensions is not prohibited but it is beyond
the Planck data possibilities.Comment: 15 pages, 10 figures; accepted by the European Physical Journal
Universal lineshape of the Kondo zero-bias anomaly in a quantum dot
Encouraged by the recent real-time renormalization group results we carried
out a detailed analysis of the nonequilibrium Kondo conductance observed in an
InAs nanowire-based quantum dot and found them to be in excellent agreement. We
show that in a wide range of bias the Kondo conductance zero-bias anomaly is
scaled by the Kondo temperature to a universal lineshape predicted by the
numerical study. The lineshape can be approximated by a phenomenological
expression of a single argument . The knowledge of
an analytical expression for the lineshape provides an alternative way for
estimation of the Kondo temperature in a real experiment, with no need for time
consuming temperature dependence measurements of the linear conductance.Comment: 5 pages, 3 figure
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