158 research outputs found
N=4 mechanics, WDVV equations and roots
N=4 superconformal multi-particle quantum mechanics on the real line is
governed by two prepotentials, U and F, which obey a system of partial
differential equations linear in U and generalizing the
Witten-Dijkgraaf-Verlinde-Verlinde (WDVV) equation for F. Putting U=0 yields a
class of models (with zero central charge) which are encoded by the finite
Coxeter root systems. We extend these WDVV solutions F in two ways: the A_n
system is deformed n-parametrically to the edge set of a general orthocentric
n-simplex, and the BCF-type systems form one-parameter families. A
classification strategy is proposed. A nonzero central charge requires turning
on U in a given F background, which we show is outside of reach of the standard
root-system ansatz for indecomposable systems of more than three particles. In
the three-body case, however, this ansatz can be generalized to establish a
series of nontrivial models based on the dihedral groups I_2(p), which are
permutation symmetric if 3 divides p. We explicitly present their full
prepotentials.Comment: 1+25 pages; v2: major revision (more general analysis, new solutions,
additional references); v3: improvements in sects.5,8,9, refs. adde
Non-backtracking walks reveal compartments in sparse chromatin interaction networks
Chromatin communities stabilized by protein machinery play essential role in
gene regulation and refine global polymeric folding of the chromatin fiber.
However, treatment of these communities in the framework of the classical
network theory (stochastic block model, SBM) does not take into account
intrinsic linear connectivity of the chromatin loci. Here we propose the
"polymer" block model, paving the way for community detection in polymer
networks. On the basis of this new model we modify the non-backtracking flow
operator and suggest the first protocol for annotation of compartmental domains
in sparse single cell Hi-C matrices. In particular, we prove that our approach
corresponds to the maximum entropy principle. The benchmark analyses
demonstrates that the spectrum of the polymer non-backtracking operator
resolves the true compartmental structure up to the theoretical detectability
threshold, while all commonly used operators fail above it. We test various
operators on real data and conclude that the sizes of the non-backtracking
single cell domains are most close to the sizes of compartments from the
population data. Moreover, the found domains clearly segregate in the gene
density and correlate with the population compartmental mask, corroborating
biological significance of our annotation of the chromatin compartmental
domains in single cells Hi-C matrices
ЭКСПОРТ ВЫСШЕГО ОБРАЗОВАНИЯ: СОСТОЯНИЕ И ПЕРСПЕКТИВЫ В МИРЕ И РОССИИ
Статья посвящена экспорту высшего образования, приобретающему все более важное значение в стратегиях социально-экономического развития в различных странах мира. Эксперты оценивают мировой рынок высшего образования в 150 млрд. долл. США. Россия в настоящее время занимает менее 1% этого рынка. Впервые предпринимается попытка оценить вклад иностранных студентов, обучающихся в РФ, в экономику страны. Для проведения расчетов были использованы данные по численности иностранных студентов в 2013/2014 учебном году, обучавшихся в российских вузах. Показано, что за рассматриваемый период иностранные студенты потратили в России примерно 25,4 млрд. руб. Даны рекомендации по первоочередным мерам по расширению российского экспорта высшего образования.
A study of the centrally produced baryon-antibaryon systems in pp interactions at 450 GeV/c
A study of the centrally produced ppbar, ppbarpi, ppbarpipi and lambda lambda
channels has been performed in pp collisions using an incident beam momentum of
450 GeV/c. No significant new structures are observed in the mass spectra,
however, important new information on the production dynamics is obtained. A
systematic study of the production properties of these systems has been
performed and it is found that these systems are not produced dominantly by
double Pomeron exchange.Comment: 13 pages, Latex, 4 Figure
A study of pseudoscalar states produced centrally in pp interactions at 450 GeV/c
A study has been made of pseudoscalar mesons produced centrally in pp
interactions. The results show that the eta and etaprime appear to have a
similar production mechanism which differs from that of the pi0. The production
properties of the eta and etaprime are not consistent with what is expected
from double Pomeron exchange. In addition the production mechanism for the eta
and etaprime is such that the production cross section are greatest when the
azimuthal angle between the pT vectors of the two protons is 90 degrees.Comment: 11 pages, Latex, 3 Figure
A measurement of the branching fractions of the f1(1285) and f1(1420) produced in central pp interactions at 450 GeV/c
A study of the f1(1285) and f1(1420) produced in central pp interactions has
been performed. For the first time in a single experiment the branching
fractions of both mesons in all major decay modes have been determined. Both
the f1(1285) and f1(1420) are consistent with being produced by double Pomeron
exchange.Comment: 15 pages, Latex, 5 Figures, submitted to Physics Letters
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