19,912 research outputs found
Dirac operators on quantum two spheres
We investigate the spin fermions on quantum two spheres. It is shown
that the wave functions of fermions and a Dirac Operator on quantum two spheres
can be constructed in a manifestly covariant way under the quantum group
. The concept of total angular momentum and chirality can be expressed
by using -analog of Pauli-matrices and appropriate commutation relations.Comment: 11 page
The Lipatov Kernels
Leading plus next-to leading log results for the Regge limit of massless
Yang-Mills theories are reproduced by reggeon diagrams in which the Regge slope
and reggeon amplitudes satisfy Ward identity constraints at
zero transverse momentum. Using reggeon unitarity together with multiple
discontinuity theory a complete set of such diagrams can be constructed. The
resulting two-two, one-three and two-four kernels which generalise the Lipatov
equation at are determined uniquely.Comment: 12 pages, ANL-HEP-PR-94-2
A conjectural generating function for numbers of curves on surfaces
I give a conjectural generating function for the numbers of -nodal
curves in a linear system of dimension on an algebraic surface. It
reproduces the results of Vainsencher for the case and
Kleiman-Piene for the case . The numbers of curves are expressed
in terms of five universal power series, three of which I give explicitly as
quasimodular forms. This gives in particular the numbers of curves of arbitrary
genus on a K3 surface and an abelian surface in terms of quasimodular forms,
generalizing the formula of Yau-Zaslow for rational curves on K3 surfaces. The
coefficients of the other two power series can be determined by comparing with
the recursive formulas of Caporaso-Harris for the Severi degrees in . We
verify the conjecture for genus 2 curves on an abelian surface. We also discuss
a link of this problem with Hilbert schemes of points.Comment: amslatex 13 page
Nuclear Physics for Cultural Heritage
Nuclear physics applications in medicine and energy are well known and widely reported. Less well known are the many important nuclear and related techniques used for the study, characterization, assessment and preservation of cultural heritage. There has been enormous progress in this field in recent years and the current review aims to provide the public with a popular and accessible account of this work.
The Nuclear Physics Division of the EPS represents scientists from all branches of nuclear physics across Europe. One of its aims is the dissemination of knowledge about nuclear physics and its applications. This review is led by Division board member Anna Macková, Head of the Tandetron Laboratory at the Nuclear Physics Institute of the Czech Academy of Sciences, and the review committee includes four other members of the nuclear physics board interested in this area: Faiçal Azaiez, Johan Nyberg, Eli Piasetzky and Douglas MacGregor. To create a truly authoritative account, the Scientific Editors have invited contributions from leading experts across Europe, and this publication is the combined result of their work.
The review is extensively illustrated with important discoveries and examples from archaeology, pre-history, history, geography, culture, religion and curation, which underline the breadth and importance of this field. The large number of groups and laboratories working in the study and preservation of cultural heritage across Europe indicate the enormous effort and importance attached by society to this activity
GASTOF: Ultra-fast ToF forward detector for exclusive processes at the LHC
GASTOF (Gas Time-of-Flight) detector is a Cherenkov detector proposed for
very precise (10--20 ps) arrival time measurements of forward protons at some
420 m from the central detectors of CMS and ATLAS. Such an excellent time
resolution will allow by z-by-timing technique for precise measurement of the
z-coordinate of the event vertex in exclusive production at the LHC, when two
colliding protons are scattered at very small angles. In the paper we present
first GASTOF prototype, simulations of its performance as well as first tests
using a cosmic muon telescope.Comment: 6 pages, 3 figures, presented at the conference ''Physics at LHC'',
Krakow, June 200
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