Publikationer från tidigare år
PUBLIKATIONER 2017

Black holes as bubbles of AdS
Authors: Ulf Danielsson, Giuseppe Dibitetto, Suvendu Giri
Preprint number: UUITP15/17
In this paper we propose that bubbles of AdS within Minkowski spacetime, stablized at a finite radius by stiff matter and an electromagnetic gas, can be an alternative endpoint of gravitational collapse. The bubbles are horizonless with a size up to 12.5% larger than their Schwarzschild radius depending on their charge. We argue that they are stable against small perturbations, and have thermodynamical properties similar to those of real black holes. We provide a realization of the bubbles within string theory that relies on a specific brane intersection giving rise to a shell carrying dissolved charges from lower dimensional Dbranes as well as a gas of open strings. We also note that our construction proivdes a new way of understanding the entropy of ReissnerNordström black holes in the extremal limit.

Twopoint functions of SU(2)subsector and lengthtwo operators in dCFT
Authors: Erik Widen
Preprint number: UUITP14/17
We consider a particular set of twopoint functions in the setting of N = 4 SYM with a defect, dual to the fuzzyfunnel solution for the probe D5D3brane system. The twopoint functions in focus involve a single trace operator in the SU(2)subsector of arbitrary length and a lengthtwo operator built out of any scalars. By interpreting the contractions as a spinchain operator, simple expressions were found for the leading contribution to the twopoint functions, mapping them to earlier known formulas for the onepoint functions in this setting.

The infinitesimal moduli space of heterotic G_2 systems
Authors: Xenia de la Ossa, Magdalena Larfors, Eirik E. Svanes
Preprint number: UUITP13/17

AdS(5) compactifications with punctures in massive IIA supergravity
Authors: Ibrahima Bah, Achilleas Passias, Alessandro Tomasiello
Preprint number: UUITP12/17We find AdS(5) solutions holographically dual to compactifications of sixdimensional N=(1,0) supersymmetric field theories on Riemann surfaces with punctures. We simplify a previous analysis of supersymmetric AdS(5) IIA solutions, and with a suitable Ansatz we find explicit solutions organized in three classes, where an O8D8 stack, D6 and D4branes are simultaneously present, localized and partially localized. The D4branes are smeared over the Riemann surface and this is interpreted as the presence of a uniform distribution of punctures. For the first class we identify the corresponding sixdimensional theory as an Estring theory coupled to a quiver gauge theory. The second class of solutions lacks D6branes and its central charge scales as n^{5/2}, suggesting a fivedimensional origin for the dual field theory. The last class has elements of the previous two.

BPS Graphs: From Spectral Networks to BPS Quivers
Authors: Maxime Gabella, Pietro Longhi, Chan Y. Park and Masahito Yamazaki
Preprint number: UUITP11/17
We define “BPS graphs” on punctured Riemann surfaces associated with A_{N−1} theories of class S. BPS graphs provide a bridge between two powerful frameworks for studying the spectrum of BPS states: spectral networks and BPS quivers. They arise from degenerate spectral networks at maximal intersections of walls of marginal stability on the Coulomb branch. While the BPS spectrum is illdefined at such intersections, a BPS graph captures a useful basis of elementary BPS states. The topology of a BPS graph encodes a BPS quiver, even for higherrank theories and for theories with certain partial punctures. BPS graphs lead to a geometric realization of the combinatorics of FockGoncharov Ntriangulations and generalize them in several ways.

Elliptic modular double and 4d partition functions
Authors: Rebecca Lodin, Fabrizio Nieri, Maxim Zabzine
Preprint number: UUITP09/17
We consider 4d supersymmetric (special) unitary G quiver gauge theories on compact manifolds which are T2 fibrations over S2. We show that their partition functions are correlators of vertex operators and screening charges of the modular double version of elliptic W(G) algebras. We also consider a generating function of BPS surface defects supported on T2 and show that it can be identified with a particular coherent state in the Fock module over the elliptic Heisenberg algebra.

Oneloop tests of supersymmetric gauge theories on spheres
Authors: Joseph A. Minahan and Usman Naseer
Preprint number: UUITP08/17
We show that a recently conjectured form for perturbative supersymmetric partition functions on spheres of general dimension d is consistent with the flat space limit of 6dimensional N = 1 super YangMills. We also show that the partition functions for N = 1 8 and 9dimensional theories are consistent with their known flat space limits.

Explicit Formulae for YangMillsEinstein Amplitudes from the Double Copy
Authors: Marco Chiodaroli, Murat Gunaydin, Henrik Johansson and Radu Roiban
Preprint number: UUITP07/17
Using the doublecopy construction of YangMillsEinstein theories formulated
in our earlier work, we obtain compact presentations for singletrace
YangMillsEinstein tree amplitudes with up to five external gravitons and an
arbitrary number of gluons. These are written as linear combinations of
colororderd YangMills trees, where the coefficients are given by
color/kinematicssatisfying numerators in a YangMills+\phi^3 theory. 
Quantum String Test of Nonconformal Holography
Authors: Xinyi ChenLin, Daniel MedinaRincon and Konstantin Zarembo
Preprint number: UUITP06/17
We compute Luscher corrections to the effective string tension in the
PilchWarner background, holographically dual to N = 2* supersymmetric
YangMills theory. The same quantity can be calculated directly
from field theory by solving the localization matrix model at largeN.
We find complete agreement between the fieldtheory predictions and
explicit stringtheory calculation at strong coupling. 
Elliptic Genera of 2d (0,2) Gauge Theories from Brane Brick Models
Authors: Sebastian Franco, Dongwook Ghim, Sangmin Lee, RakKyeong Seong
Preprint Number: UUITP05/17
We compute the elliptic genus of abelian 2d (0,2) gauge theories corresponding to brane brick models. These theories are worldvolume theories on a single D1brane probing a toric CalabiYau 4fold singularity. We identify a match with the elliptic genus of the nonlinear sigma model on the same CalabiYau background, which is computed using a new localization formula. The matching implies that the quantum effects do not drastically alter the correspondence between the geometry and the 2d (0,2) gauge theory. In theories whose matter sector suffers from abelian gauge anomaly, we propose an ansatz for an anomaly cancelling term in the integral formula for the elliptic genus. We provide an example in which two brane brick models related to each other by GaddeGukovPutrov triality give the same elliptic genus.

Integrability in SigmaModels
Author: K. Zarembo
Preprint Number: UUITP04/17
Abstract: These lecture notes cover the following topics: (1) Homogeneous spaces, (2) Classical integrability of principal chiral field and semisymmetric cosets, (3) Topological terms in sigmamodels, (4) Backroundfield method and betafunction, (5) Smatrix bootstrap in the $O(N)$ model, (6) Supersymmetric cosets.

Connecting Fisher information to bulk entanglement in holography
Authors: Souvik Banerjee, Johanna Erdmenger, Debajyoti Sarkar
Preprint: UUITP03/17
Abstract: In the context of relating AdS/CFT to quantum information theory, we propose a holographic dual of Fisher information metric for mixed states in the boundary field theory. This amounts to a holographic measure for the distance between two mixed quantum states. For a spherical subregion in the boundary we show that this is related to a particularly regularized volume enclosed by the RyuTakayanagi surface. We further argue that the quantum correction to the proposed Fisher information metric is related to the quantum correction to the boundary entanglement entropy. We discuss consequences of this connection.

Semiholography illustrated with biholography
Authors : Souvik Banerjee, Nava Gaddam, Ayan Mukhopadhyay
Preprint number : UUITP02/17
Abstract : Semiholography has been proposed as an effective nonperturbative framework which can combine perturbative and nonperturbative effects consistently for theories like QCD. It is postulated that the strongly coupled nonperturbative sector has a holographic dual in the form of a classical gravity theory in the large N limit, and the perturbative fields determine the gravitational boundary conditions. In this work, we pursue a fundamental derivation of this framework particularly showing how perturbative physics by itself can determine the holographic dual of the infrared, and also the interactions between the perturbative and the holographic sectors. We firstly demonstrate that the interactions between the two sectors can be constrained through the existence of a conserved local energymomentum tensor for the full system up to hardsoft coupling constants. As an illustration, we set up a biholographic toy theory where both the UV and IR sectors are strongly coupled and holographic with distinct classical gravity duals. In this construction, the requirement that an appropriate gluing can cure the singularities (geodetic incompletenesses) of the respective geometries leads us to determine the parameters of the IR theory and the hardsoft couplings in terms of those of the UV theory. The high energy scale behaviour of the hardsoft couplings are stateindependent but their runnings turn out to be statedependent. We discuss how our approach can be adapted to the construction of the semiholographic framework for QCD.

Gravity Amplitudes as Generalized Double Copies
Authors: Zvi Bern, John Joseph Carrasco, WeiMing Chen, Henrik Johansson, Radu Roiban
Preprint Number: UUITP01/17
Whenever a gaugetheory integrand can be arranged into a form where the BCJ duality between color and kinematics is manifest, a corresponding gravity integrand can be obtained directly via the double copy procedure. However, finding such representations at loop level can be challenging. Here we show that we can instead start from generic gaugetheory integrands, where the duality is not manifest, and apply a modified doublecopy procedure that incorporates a set of contact terms generated by violations of dual Jacobi identities. We illustrate this with three, four and fiveloop examples in N = 8 supergravity.