2,026 research outputs found
The cosmic ray differential diurnal variation dependences on the zenith angle and the geomagnetic disturbance
Simultaneous and continuous muon measurements in two opposite azimuthal directions under equal zenith angles demonstrated the importance of this method for cosmic ray diurnal variation investigations. Lately these measurements were extended by means of improved telescopes. The obtained cosmic ray diurnal variations were presented as intensity differential curves. Theoretical investigations connected the properties of these curves with some interplanetary spece parameters. The harmonics of these curves were interpreted physically. Some order difference curves were introduced. In earlier works some dependences between the parameters characterizing the first and the second harmonics of the differential intensity curves and the geomagnetic activity were found. Then all measurements were carried out under only one zenith angle. The results of investigations of similar dependences using data of simultaneous measurements under three different zenith angles are presented
A Unified Conformal Field Theory Description of Paired Quantum Hall States
The wave functions of the Haldane-Rezayi paired Hall state have been
previously described by a non-unitary conformal field theory with central
charge c=-2. Moreover, a relation with the c=1 unitary Weyl fermion has been
suggested. We construct the complete unitary theory and show that it
consistently describes the edge excitations of the Haldane-Rezayi state.
Actually, we show that the unitary (c=1) and non-unitary (c=-2) theories are
related by a local map between the two sets of fields and by a suitable change
of conjugation. The unitary theory of the Haldane-Rezayi state is found to be
the same as that of the 331 paired Hall state. Furthermore, the analysis of
modular invariant partition functions shows that no alternative unitary
descriptions are possible for the Haldane-Rezayi state within the class of
rational conformal field theories with abelian current algebra. Finally, the
known c=3/2 conformal theory of the Pfaffian state is also obtained from the
331 theory by a reduction of degrees of freedom which can be physically
realized in the double-layer Hall systems.Comment: Latex, 42 pages, 2 figures, 3 tables; minor corrections to text and
reference
The catalogue of OB associations in IC 1613
We present a catalogue of OB associations in IC 1613. Using an automatic and
objective method (Battinelli's 1991 technique) 60 objects were found. The size
distribution reveals a significant peak at about 60 parsecs if a distance
modulus of 24.27 mag is assumed. Spatial distributions of the detected
associations and H II regions are strongly correlated.Comment: 5 pages, 3 figures, A&A accepte
Optical-NIR analysis of globular clusters in the IKN dwarf spheroidal: a complex star formation history
Age, metallicity and spatial distribution of globular clusters (GCs) provide
a powerful tool to reconstruct major star-formation episodes in galaxies. IKN
is a faint dwarf spheroidal (dSph) in the M81 group of galaxies. It contains
five old GCs, which makes it the galaxy with the highest known specific
frequency (SN=126). We estimate the photometric age, metallicity and spatial
distribution of the poorly studied IKN GCs. We search SDSS for GC candidates
beyond the HST field of view, which covers half of IKN. To break the
age-metallicity degeneracy in the V-I colour we use WHT/LIRIS Ks-band
photometry and derive photometric ages and metallicities by comparison with SSP
models in the V,I,Ks colour space. IKN GCs' VIKs colours are consistent with
old ages ( Gyr) and a metallicity distribution with a higher mean than
typical for such a dSph ([Fe/H dex). Their
photometric masses range () implies
a high mass ratio between GCs and field stars, of . Mixture model
analysis of the RGB field stars' metallicity suggests that 72\% of the stars
may have formed together with the GCs. Using the most massive GC-SFR relation
we calculate a SFR of yr during its formation epoch. We note
that the more massive GCs are closer to the galaxy photometric centre. IKN GCs
also appear spatially aligned along a line close to the IKN major-axis and
nearly orthogonal to the plane of spatial distribution of galaxies in the M81
group. We identify one new IKN GC candidate based on colour and PSF analysis of
the SDSS data. The evidence towards i) broad and high metallicity distribution
of the field IKN RGB stars and its GCs, ii) high fraction and iii), spatial
alignment of IKN GCs, supports a scenario for tidally triggered complex IKN's
SFH in the context of interactions with galaxies in the M81 group.Comment: 12 pages, 9 figures, accepted to A&
Computational equivalence of the two inequivalent spinor representations of the braid group in the Ising topological quantum computer
We demonstrate that the two inequivalent spinor representations of the braid
group \B_{2n+2}, describing the exchanges of 2n+2 non-Abelian Ising anyons in
the Pfaffian topological quantum computer, are equivalent from computational
point of view, i.e., the sets of topologically protected quantum gates that
could be implemented in both cases by braiding exactly coincide. We give the
explicit matrices generating almost all braidings in the spinor representations
of the 2n+2 Ising anyons, as well as important recurrence relations. Our
detailed analysis allows us to understand better the physical difference
between the two inequivalent representations and to propose a process that
could determine the type of representation for any concrete physical
realization of the Pfaffian quantum computer.Comment: 9 pages, 2 figures, published versio
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