223 research outputs found
FPT-algorithms for some problems related to integer programming
In this paper, we present FPT-algorithms for special cases of the shortest
lattice vector, integer linear programming, and simplex width computation
problems, when matrices included in the problems' formulations are near square.
The parameter is the maximum absolute value of rank minors of the corresponding
matrices. Additionally, we present FPT-algorithms with respect to the same
parameter for the problems, when the matrices have no singular rank
sub-matrices.Comment: arXiv admin note: text overlap with arXiv:1710.00321 From author:
some minor corrections has been don
Kinematic and vertex fitting package for the CMD-3 experiment
In this article, we discuss a new software package of kinematic and vertex
fitting for the CMD-3 experiment at the VEPP-2000 electron-positron collider.
The authors describe in detail the fitting algorithm, parametrization of
four-momenta and trajectories of various particles and present the results of
testing the fitting package using events of Monte Carlo simulation of various
annihilation processes. The authors also provide several examples of
the fitting package validation using Gaussian simulation. Although the package
discussed in this article is intended for the CMD-3 experiment, it can also be
used in other experiments. The authors consider the described package as their
first step towards a more universal and rigrous kinematic and vertex fitting
package that can be used in future experiments, such as the Super
Charm-Tau factory
A faster algorithm for counting the integer points number in -modular polyhedra
Let a polytope be defined by a system . We consider the
problem to count a number of integer points inside , assuming that is
-modular. The polytope is -modular if all the rank
sub-determinants of are bounded by in the absolute value. We
present a new FPT-algorithm, parameterized by and by the number of
simple cones in the normal fun triangulation of , which is more efficient
for -modular problems, than the approach of A.~Barvinok et al. To this
end, we do not directly compute the short rational generating function for , which is commonly used for the considered problem. We compute its
particular representation in the form of exponential series that depends on one
variable, using the dynamic programming principle. We completely do not use the
A.~Barvinok's unimodular sign decomposition technique. Using our new complexity
bound, we consider different special cases that may be of independent interest.
For example, we give FPT-algorithms for counting the integer points number in
-modular simplicies and similar polytopes that have facets.
For any fixed , we give an FPT-algorithm to count solutions of the unbounded
-dimensional -modular knapsack problem. For the case, when
grows slowly with respect to , we give a counting algorithm, which is more
effective, than the state of the art ILP feasibility algorithm
Hamiltonian structures of fermionic two-dimensional Toda lattice hierarchies
By exhibiting the corresponding Lax pair representations we propose a wide
class of integrable two-dimensional (2D) fermionic Toda lattice (TL)
hierarchies which includes the 2D N=(2|2) and N=(0|2) supersymmetric TL
hierarchies as particular cases. We develop the generalized graded R-matrix
formalism using the generalized graded bracket on the space of graded operators
with involution generalizing the graded commutator in superalgebras, which
allows one to describe these hierarchies in the framework of the Hamiltonian
formalism and construct their first two Hamiltonian structures. The first
Hamiltonian structure is obtained for both bosonic and fermionic Lax operators
while the second Hamiltonian structure is established for bosonic Lax operators
only.Comment: 12 pages, LaTeX, the talks delivered at the International Workshop on
Classical and Quantum Integrable Systems (Dubna, January 24 - 28, 2005) and
International Conference on Theoretical Physics (Moscow, April 11 - 16, 2005
Hadronic structure aspects of decays
As is known from previous studies the lepton number violating decays have good prospects to probe new physics beyond the
Standard Model and provide valuable information on neutrino masses and mixing.
We analyze these processes with an emphasis on their hadronic structure
aspects applying relativistic constituent quark model. We conclude that the
previously ignored contribution associated with the t-channel Majorana neutrino
exchange is comparable with the s-channel one in a wide range of neutrino
masses. We also estimated model independent absolute upper bounds on neutrino
contribution to these decays.Comment: 15 pages, 1 figure. Version to appear in PRD, normalization factor in
Eq. (25) is correcte
Nonlinear Realizations of the Algebra
In this letter we consider the nonlinear realizations of the classical
Polyakov's algebra . The coset space method and the covariant
reduction procedure allow us to deduce the Boussinesq equation with
interchanged space and evolution coordinates. By adding one more space
coordinate and introducing two copies of the algebra, the same
method yields the Toda lattice equations.Comment: LaTeX, 10p., Preprint LNF-94/013 (P
AC/DC Susceptibility of the Heavy-Fermion Superconductor CePt3Si under Pressure
We have investigated the pressure dependence of ac and dc susceptibilities of
the heavy-fermion superconductor CePt3Si (Tc= 0.75 K) that coexists with
antiferromagnetism (TN = 2.2 K). As hydrostatic pressure is increased, Tc first
decreases rapidly, then rather slowly near the critical pressure Pc = 0.6 GPa
and shows a stronger decrease again at higher pressures, where Pc is the
pressure at which TN becomes zero. A transition width and a difference in the
two transition temperatures defined in the form of structures in the
out-of-phase component of ac susceptibilities also become small near Pc,
indicating that a double transition observed in CePt3Si is caused by some
inhomogeneous property in the sample that leads to a spatial variation of local
pressure. A sudden increase in the Meissner fraction above Pc suggests the
influence of antiferromagnetism on superconductivity.Comment: 4 pages with 5 figures. This paper will be published in J. Phys. Soc.
Jp
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