UEICMSNew Seminar Room
FIRST seminar
SECOND seminar
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ICMSNew Seminar Room2016-09-28Daniel GrumillerVienna Tech. U.Preseminar for PhD StudentsDaniel GrumillerVienna Tech. U.Soft Heisenberg hairThe notion of "soft hair" refers to zero energy excitations in the near horizon region of black holes or cosmologies, advocated by Hawking, Perry and Strominger. I review recent results on soft hair in three spacetime dimensions. In particular, I focus on the near horizon symmetry algebra, which turns out to be surprisingly simple, namely infinite copies of the Heisenberg algebra. The results are universal (in a sense that I shall make precise) and could generalize to higher dimensions.
Andrius StikonasUoEScrambling time in eternal BTZ black holeIt is usually hard to compute entanglement entropy and mutual information for
conformal field theories (CFT). Ryu-Takayanagi proposals allows us to find the
same quantities using calculations in gravity. In this talk I will show how to
find holographic entanglement entropy and scrambling time for BTZ black hole
perturbed by a heavy (backreacting) particle. Holographic bulk description
improves on the schock-wave approximation in 3d bulk dimensions. I will also
discuss current attempts to generalize this calculation to the rotating BTZ
black hole.
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ICMSNew Seminar Room2016-10-12Yutaka MatsuoTokyo U.Preseminar for PhD StudentsGlenn BarnichBrussels U.Finite BMS transformationsAfter a review of holographic features of general relativity in 3 and 4 dimensions, I will show how to derive the transformation laws of the Bondi mass and angular momentum aspects under finite supertranslations, superrotations and complex Weyl rescalings.
Yutaka MatsuoTokyo U.Quantum Seiberg-Witten curve and q-deformed W(infinity) algebraA few years ago, Nekrasov and his collaborators proposed
a double quantum deformation of Seiberg-Witten curve with omega background parameters
which describes 4D and 5D supersymetric gauge theories.
It illuminates not only the quantization of geometry but also gives an intimate relation with
integrable models. In this talk, we present a purely algebraic derivation of his proposal, based
on the quantum deformation of W(infinity) algebra. We introduced the building blocks of
Nekrasov partition function, Gaiotto state, intertwiner and so on, and a simple characterization
of such states and operators. It gives the qq-deformed SW curve in the form of Ward identities.
The connection with the integrable models will be also explained to some detail.
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ICMSNew Seminar Room2016-10-26Marc HellerTohoku U.Preseminar for PhD StudentsOlivier Blondeau-FournierKing's Coll. LondonMeasures of entanglement in CFT/QFTFor bi-partite quantum systems, the amount of entanglement between the two regions can be expressed by the entanglement entropy. There are other related quantities such as the Renyi entropy or the logarithm negativity, which are also important. In general, these quantities are difficult to evaluate due to the explicit dependence of the reduced density matrix that needs to be diagonalized. In the scaling limit, one can use quantum field theory (QFT) to find exact results and universal behaviour. In particular, in the context of conformal field theory (CFT), the Renyi entropy has two equivalent interpretations. The first one is of geometric type, because it is given by the evaluation of a partition function on a Riemann surface of higher genus. In principle such partition functions are classified by modular invariance, but for general Riemann surfaces only the set of theories that have central charge equal to one are explicitly known. The second interpretation is algebraic. The Renyi entropy can be written as a correlator of twist fields. These fields live in a extended version of the Virasoro algebra, usually referred to as the cyclic orbifold CFT, where they are associated to branch points on the sphere. This second point of view is particularly useful because when one consider theory away from criticality, or in a massive QFT, correlators of twist fields can be calculated using the form factor program.
Marc HellerTohoku U.Higher Gauge Theories from Lie n-algebras and Off-Shell
CovariantizationIn M-theory, M5-branes interact by M2-branes extending between them. The
one-dimensional intersections are so-called selfdual strings charged under
a selfdual 2-form field. Their dynamics is governed by higher gauge
theories. We construct higher gauge theories containing 2- and 3-form
curvatures in various dimensions making use of the supergeometric
QP-manifold method, which induces a BRST-BV formalism. Structurally
equivalent higher gauge theories are identified on the gauge algebra
level. A method of off-shell covariantization is proposed that achieves to
covariantize the gauge transformation of the 3-form curvature while
circumventing the so-called fake curvature condition by constraining the
auxiliary gauge fields. We explicitly derive such a gauge algebra in 5
dimensions as a nontrivial extension of a differential crossed module
within a symplectic Lie 4-algebra and show its off-shell closure.
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ICMSNew Seminar Room2016-11-09Preseminar for PhD StudentsManuela KulaxiziTrinity Coll. DublinAndrei ParnachevTrinity Coll. DublinUE -->
ICMSNew Seminar Room2016-11-23Alejandro de la Rosa GomezYork U.Preseminar for PhD StudentsAndrea SantiBologna U.Alejandro de la Rosa GomezYork U.Folding a spin chain: integrable boundaries of the XXX and the Inozemtsev hyperbolic modelsI will present a general method of folding an integrable spin chain, defined on a line, to obtain an integrable open spin chain, defined on a half-line. I will illustrate this method through two fundamental models with sl(2) Lie algebra symmetry: the Heisenberg XXX and the Inozemtsev hyperbolic spin chains. New long-range boundary Hamiltonians are obtained, and I will demonstrate that they exhibit Yangian symmetries, thus ensuring integrability. The method presented provides a "bottom-up" approach for constructing integrable boundaries and can be applied to any spin chain model.
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ICMSNew Seminar Room2016-12-07Emanuel MalekMunich U.Preseminar for PhD StudentsEmanuel MalekMunich U.UE -->
ICMSNew Seminar Room2017-01-18Preseminar for PhD StudentsUE -->
ICMSNew Seminar Room2017-02-01Preseminar for PhD StudentsUE -->
ICMSNew Seminar Room2017-02-15Preseminar for PhD StudentsUE -->
ICMSNew Seminar Room2017-03-01Preseminar for PhD StudentsErik PanzerOxford U.UE -->
ICMSNew Seminar Room2017-03-15Preseminar for PhD StudentsUE -->
ICMSNew Seminar Room2017-03-29Stefano CremonesiDurham U.Preseminar for PhD StudentsStefano CremonesiDurham U.UE -->
ICMSNew Seminar Room2017-05-03Preseminar for PhD StudentsUE -->
ICMSNew Seminar Room2017-05-17Preseminar for PhD StudentsUE -->
ICMSNew Seminar Room2017-05-31Preseminar for PhD Students