62,622 research outputs found
Open heavy-flavour production in pp and Pb-Pb collisions at the LHC, measured with ALICE at central rapidity
The ALICE experiment studies nucleus-nucleus collisions at the LHC in order
to investigate the properties of QCD matter at extreme energy densities. The
measurement of open charm and open beauty production allows to investigate the
interaction of heavy quarks with the hot and dense medium formed in high-energy
nucleus-nucleus collisions. In particular, in-medium energy loss is predicted
to be different for gluons, light quarks and heavy quarks and to depend on the
medium energy density and size. ALICE has measured open heavy-flavour particle
production at central rapidity in several decay channels in Pb-Pb and pp
collisions at sqrt{s_NN} = 2.76 TeV and sqrt{s} = 2.76, 7 TeV respectively. The
results obtained from the reconstruction of D meson decays at central rapidity
and from electrons from heavy-flavour hadron decay will be presented.Comment: Proceedings of the International Conference "Primordial QCD Matter in
LHC Era -Implication of QCD results on the early universe", El Cairo, 4th-8th
December 201
On the compatibility between cup products, the Alekseev--Torossian connection and the Kashiwara--Vergne conjecture
For a finite-dimensional Lie algebra over a field , we deduce from the compatibility between cup products
Kontsevich (2003, Section 8) and from the main result of Shoikhet (2001) an
alternative way of re-writing Kontsevich product on by means of the Alekseev--Torossian flat connection (Alekseev
and Torossian, 2010). We deduce a similar formula directly from the
Kashiwara--Vergne conjecture (Kashiwara and Vergne, 1978).Comment: 8 pages, 1 figure; notation changed; corrected many other misprints
recently noticed; comments are very welcome
The explicit equivalence between the standard and the logarithmic star product for Lie algebras
The purpose of this short note is to establish an explicit equivalence
between the two star products and on the symmetric
algebra of a finite-dimensional Lie algebra over a field of characteristic 0 associated with
the standard angular propagator and the logarithmic one: the differential
operator of infinite order with constant coefficients realizing the equivalence
is related to the incarnation of the Grothendieck-Teichm\"uller group
considered by Kontsevich.Comment: 2 figures; corrected and completed the formulation of Theorem 3.7.
Comments are very welcome
Recursion relations for Double Ramification Hierarchies
In this paper we study various properties of the double ramification
hierarchy, an integrable hierarchy of hamiltonian PDEs introduced in [Bur15]
using intersection theory of the double ramification cycle in the moduli space
of stable curves. In particular, we prove a recursion formula that recovers the
full hierarchy starting from just one of the Hamiltonians, the one associated
to the first descendant of the unit of a cohomological field theory. Moreover,
we introduce analogues of the topological recursion relations and the divisor
equation both for the hamiltonian densities and for the string solution of the
double ramification hierarchy. This machinery is very efficient and we apply it
to various computations for the trivial and Hodge cohomological field theories,
and for the -spin Witten's classes. Moreover we prove the Miura equivalence
between the double ramification hierarchy and the Dubrovin-Zhang hierarchy for
the Gromov-Witten theory of the complex projective line (extended Toda
hierarchy).Comment: Revised version, to be published in Communications in Mathematical
Physics, 27 page
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