4,904 research outputs found
Particle Multiplicity in Jets and Sub-jets with Jet Axis from Color Current
We study the particle multiplicity in a jet or sub-jet as derived from an
energy-multiplicity 2-particle correlation. This definition avoids the notion
of a globally fixed jet axis and allows for the study of smaller jet cone
openings in a more stable way. The results are sensitive to the mean color
current in the jet from primary parton which takes into
account intermediate partonic processes in the sub-jet production where at high energies. We generalize previous calculations in
Leading Logarithmic Approximation (LLA). The size of the effects related to
this jet axis definition are computed for multiplicities in sub-jets with
different opening angles and energies by including contributions from the
Modified LLA (MLLA) and Next-to-MLLA to the leading order QCD results
Three-particle correlations in QCD parton showers
Three-particle correlations in quark and gluon jets are computed for the
first time in perturbative QCD. We give results in the double logarithmic
approximation and the modified leading logarithmic approximation. In both
resummation schemes, we use the formalism of the generating functional and
solve the evolution equations analytically from the steepest descent evaluation
of the one-particle distribution. We thus provide a further test of the local
parton hadron duality and make predictions for the LHC.Comment: 9 pages and 5 figures. Version published by Physical Review D with
reference: Phys. Rev. D 84, 034015 (2011). Two more figures and one section
adde
On the product of two π-decomposable soluble groups
Let the group G = AB be a product of two π-decomposable sub-groups A = Oπ(A) × Oπ' (A) and B = Oπ(B) × Oπ' (B) where π is a set of primes. The authors conjecture that Oπ(A)Oπ(B) = Oπ(B)Oπ(A) if π is a set of odd primes. In this paper it is proved that the conjecture is true if A and B are soluble. A similar result with certain additional restrictions holds in the case 2 ∈ π. Moreover, it is shown that the conjecture holds if Oπ '(A) and Oπ'(B) have coprime orders
Finite trifactorized groups and pi-decomposability
The first author would like to thank the Universitat de Valencia for its warm hospitality and financial support during the preparation of this paper.Kazarin, LS.; Martínez-Pastor, A.; Perez Ramos, MD. (2018). Finite trifactorized groups and pi-decomposability. Bulletin of the Australian Mathematical Society. 97(2):218-228. https://doi.org/10.1017/S0004972717001034S21822897
High spatial resolution optical imaging of the multiple T Tauri system LkH{\alpha} 262/LkH{\alpha} 263
We report high spatial resolution i' band imaging of the multiple T Tauri
system LkH 262/LkH 263 obtained during the first commissioning
period of the Adaptive Optics Lucky Imager (AOLI) at the 4.2 m William Herschel
Telescope, using its Lucky Imaging mode. AOLI images have provided photometry
for each of the two components LkH 263 A and B (0.41 arcsec separation)
and marginal evidence for an unresolved binary or a disc in LkH 262.
The AOLI data combined with previously available and newly obtained optical and
infrared imaging show that the three components of LkH 263 are
co-moving, that there is orbital motion in the AB pair, and, remarkably, that
LkH 262-263 is a common proper motion system with less than 1 mas/yr
relative motion. We argue that this is a likely five-component gravitationally
bounded system. According to BT-settl models the mass of each of the five
components is close to 0.4 M and the age is in the range 1-2 Myr. The
presence of discs in some of the components offers an interesting opportunity
to investigate the formation and evolution of discs in the early stages of
multiple very low-mass systems. In particular, we provide tentative evidence
that the disc in 263C could be coplanar with the orbit of 263AB.Comment: 11 pages, 7 figures, Accepted 2016 May
Laboratory and telescope demonstration of the TP3-WFS for the adaptive optics segment of AOLI
AOLI (Adaptive Optics Lucky Imager) is a state-of-art instrument that combines adaptive optics (AO) and lucky imaging (LI) with the objective of obtaining diffraction limited images in visible wavelength at mid- and big-size ground-based telescopes. The key innovation of AOLI is the development and use of the new TP3-WFS (Two Pupil Plane PositionsWavefront Sensor). The TP3-WFS, working in visible band, represents an advance over classical wavefront sensors such as the Shack-Hartmann WFS (SH-WFS) because it can theoretically use fainter natural reference stars, which would ultimately provide better sky coverages to AO instruments using this newer sensor. This paper describes the software, algorithms and procedures that enabled AOLI to become the first astronomical instrument performing real-time adaptive optics corrections
in a telescope with this new type of WFS, including the first control-related
results at the William Herschel Telescope (WHT)This work was supported by the Spanish Ministry of Economy under the projects AYA2011-29024, ESP2014-56869-C2-2-P, ESP2015-69020-C2-2-R and DPI2015-66458-C2-2-R, by project 15345/PI/10 from the Fundación Séneca, by the Spanish Ministry of Education under the grant FPU12/05573, by project ST/K002368/1 from the Science and Technology Facilities Council and by ERDF funds from the European Commission. The results presented in this paper are based on observations made with the William Herschel Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. Special thanks go to Lara Monteagudo and Marcos Pellejero for their timely contributions
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