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CATEGORIES:Quantum Fields and Strings Seminars
SUMMARY:Covariant phase space with boundaries - Daniel Har
low (MIT)
DTSTART;TZID=Europe/London:20200604T140000
DTEND;TZID=Europe/London:20200604T150000
UID:TALK143722AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/143722
DESCRIPTION:The Hamiltonian formulation of mechanics has sever
al decisive advantages: it gives a clear accountin
g of the physical degrees of freedom\, the initial
-value problem is naturally formulated\, and the r
elationship to quantum mechanics is clear. On the
other hand\, as usually formulated it destroys man
ifest spacetime covariance and applies only to equ
ations of motion with at most two derivatives. Bot
h of these problems are avoided in the covariant p
hase space formalism\, developed most notably by W
ald and collaborators in the early 1990s. Their fo
rmalism however suffers from ambiguities related t
o total derivatives and boundary terms\, which so
far have been dealt with on an ad hoc case-by-case
basis. This is especially unfortunate for gravita
tional theories\, for which any nontrivial Hamilto
nian will necessarily be a boundary term and thus
boundary effects are of central importance. In thi
s talk I will describe work with Jie-qiang Wu wher
e we improve the covariant phase space formalism t
o systematically include boundary effects: the res
ult is that for any Lagrangian field theory based
on a local action with a finite number of derivati
ves\, there is now a systematic\, practical\, and
fully-covariant way to construct the phase space a
nd Hamiltonian\, as well as any other conserved ch
arges. Moreover the approach is quite convenient i
n practice\, for example it allows perhaps the mos
t compact derivation so far of the ADM Hamiltonian
.
LOCATION:Online (Zoom)
CONTACT:Pietro Benetti Genolini
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