# Calendar of Physics Talks Vienna

 Operads, factorization algebras, and (topological) quantum field theory with a flavor of higher categories
 Speaker: Claudia Scheimbauer (MPI Bonn) Abstract: (This is an introductory lecture series running every day for one week.) The main goal of this Lecture Course is to give an introduction to certain algebraic structures arising in the study of (topological) quantum field theory. Operads, introduced by May, form a framework to abstract families of composable functions in a systematic way and have appeared in many fields of mathematics, such as topology, homological algebra, algebraic geometry, and mathematical physics. We will encounter algebraic examples such as the associative and commutative operad (encoding associative and commutative algebras) and examples of a topological nature, called the little $n$-disks operad (encoding the structure of $n$-fold loop spaces). Factorization algebras, first introduced by Beilinson and Drinfeld in an algebro-geometric context, are algebraic structures which give a way to encode the struc Date: Mon, 29.02.2016 Time: 11:15 Duration: 90 min Location: ESI Contact: Nils Carqueville

 Simons Lecture Series: Operads, factorization algebras, and (topological) quantum field theory with a flavor of higher categories
 Speaker: Claudia Scheimbauer (MPI Bonn) Abstract: The main goal of this Lecture Course is to give an introduction to certain algebraic structures arising in the study of (topological) quantum field theory. Operads, introduced by May, form a framework to abstract families of composable functions in a systematic way and have become appeared in many fields of mathematics, such as topology, homological algebra, algebraic geometry, and mathematical physics. We will encounter algebraic examples such as the associative and commutative operad (encoding associative and commutative algebras) and examples of a topological nature, called the little $n$-disks operad (encoding the structure of $n$-fold loop spaces). Factorization algebras, first introduced by Beilinson and Drinfeld in an algebro-geometric context, are algebraic structures which give a way to encode the structure of observables of a perturbative quantum field theory. Date: Mon, 29.02.2016 Time: 11:15 Location: Erwin Schrödinger International Institute, Boltzmanngasse 9, 1090 Wien, Schrödinger lecture hall Contact: secr@esi.ac.at

 Informal talk on profinite groups
 Speaker: Prof. John Wilson (U Oxford) Date: Tue, 01.03.2016 Time: 10:30 Location: Erwin Schrödinger International Institute, Boltzmanngasse 9, 1090 Wien, Boltzmann lecture hall Contact: secr@esi.ac.at

 Non-Leptonic Multibody B Decays in QCD Factorization: First Results
 Speaker: Thomas Mannel (Univ. Siegen) Abstract: im Rahmen des Teilchenphysik-Seminars Date: Tue, 01.03.2016 Time: 16:15 Duration: 60 min Location: Fakultät für Physik, Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock Contact: A. Hoang, H. Neufeld

 Gravitating waveguides
 Speaker: Timon Gutleb (Univ. Wien) Abstract: im Rahmen des Literaturseminars der Gravitationsphysik: The commonly introduced description of electromagnetism in curved spacetime is concise and elegant but not particularly useful when describing materials of spatially dependent permittivity $\epsilon$. Thus, discussions of waveguides are typically limited to classical electromagnetism. In this talk, I will work towards a description of electromagnetism in curved spacetime that can be useful to discuss planar waveguides in a weak gravitational field while highlighting the difficulties in notation and convention that arise in the interdisciplinary context. Date: Thu, 03.03.2016 Time: 14:00 Duration: 60 min Location: Arbeitsgruppe Gravitation, Währinger Strasse 17, Seminarraum A, 2. Stock, 1090 Wien Contact: H. Rumpf

 Strange values of L2-Betti numbers for positive characteristic
 Speaker: Prof. Thomas Schick (U Göttingen) Abstract: Classical L2-Betti numbers for a group G (or more generally for spaces with free G-action) can be defined as a limit of ordinary Betti numbers via approximations of a group by finite objects (finite quotients; more general sofic approximations). These approximation results are theorems (the initial one due to L\"uck). Date: Thu, 03.03.2016 Time: 14:00 Location: Erwin Schrödinger International Institute, Boltzmanngasse 9, 1090 Wien, Boltzmann lecture hall Contact: secr@esi.ac.at

 An ultimate target for dark matter searches
 Speaker: Kfir Blum (Weizmann Institute) Abstract: The combination of S-matrix unitarity and the dynamics of thermal freeze-out for massive relic particles (denoted here by WIMPs) implies a lower limit on the cosmological mass density of such particles. We show that this translates to lower limits to the signal rates for a variety of techniques for direct and indirect detection of dark matter. Focusing on models where annihilation is s-wave dominated, we derive lower limits to the flux of gamma-rays from WIMP annihilation at the Galactic center; direct detection of WIMPs; energetic neutrinos from WIMP annihilation in the Sun; and the effects of WIMPs on the angular power spectrum and frequency spectrum of the cosmic microwave background radiation. The results suggest that a variety of dark-matter-search techniques may provide interesting avenues to seek new physics, even if WIMPs make up only a small fraction of the total dark matter. Date: Thu, 03.03.2016 Time: 14:00 Duration: 60 min Location: Institute of High Energy Physics, Library, Nikolsdorfer Gasse 18, 1050 Wien Contact: Jochen.Schieck@oeaw.ac.at

 Weyl Anomalies and Quantum Cosmology
 Speaker: Teresa Bautista (Paris, LPTHE & UPMC, Paris) Abstract: I will talk about the cosmological consequences of Weyl anomalies arising from the renormalization of composite operators in a theory of gravity with a cosmological constant. Near two dimensions, the relevant anomaly can be computed explicitly using results from Liouville theory and leads to a non-local quantum effective action. The resulting quantum energy momentum tensor is non-local and leads to a decaying vacuum energy in a homogeneous and isotropic expanding universe. I will discuss a generalization of these results to four dimensions and possible implications for inflation and de Sitter spacetime. Date: Fri, 04.03.2016 Time: 14:00 Duration: 60 min Location: SEM 136, TU Wien, Freihaus, 10th floor (Wiedner Hauptstr. 8-10, A-1040 Vienna) Contact: Daniel Grumiller

 String Theory for Pedestrians
 Speaker: Johanna Knapp (TU Wien) Abstract: In this overview talk aimed at non-experts we discuss the basic features of String Theory. This theory is supposed to provide a unified description of the fundamental forces of nature. In particular we will discuss: unification of forces, extra dimensions, supersymmetry and string dualities. Furthermore an overview of modern applications of string theory will be given. Date: Fri, 04.03.2016 Time: 15:30 Location: Atominstitut, Hörsaal, Stadionallee 2, Wien 2 Contact: J. Schmiedmayer