ELFT HÍRADÓ

["Szabados,L." <lbszab AT rmki.kfki.hu>]

RELATIVITASELMELETI SZEMINARIUM


Eloado:  Prof James M Nester
         National Central University, Chungli, Taiwan

Az eloadas cime:  On dynamics with derivative constraints

t:       2021 junius 21 (csutortok), 14.00
(x,y,z): KFKI RMKI III. epulet, tanacsterem

Kivonat:
We begin with classical mechanical systems with velocity
constraints. For general nonholonomic velocity constraints, the
desired equations cannot be obtained by including such constraints
into the action with a Lagrange multiplier.  From a simple argument we
obtain the appropriate (Chetaev) form of the necessary constraint
force which is to be included in d'Alembert's principle. Some results
on symmetries and conserved quantities and conditions under which a
unique constraint force can be obtained along with Dirac type
constraints are noted.  Applications to the proper dynamical equations
of relativistic particles are presented.  Turning to the field theory
analogue---derivative constraints---the straightforward generalization
of the Chetaev constraint force does not seem to have the desired
properties in general.  For gravity theories certain geometrically
meaningful derivative constraints can be included into the action with
Lagrange multipliers, but for the variation of our quasi-local energy
expression we have not yet learned how to incorporate the necessary
derivative constraints to obtain a good set of differential equations.