122 research outputs found

### Exceptional $\mathcal N=3$ theories

We present a new construction of four dimensional $\mathcal N=3$ theories,
given by M5 branes wrapping a $T^2$ in an M-theory U-fold background. The
resulting setup generalizes the one used in the usual class $\mathcal S$
construction of four dimensional theories by using an extra discrete symmetry
on the M5 worldvolume. Together with the M-theory U-fold description of $(0,2)$
$E$-type six-dimensional SCFTs, this allows to construct new, exceptional,
$\mathcal N=3$ theories.Comment: v2: Minor modifications, version to appear in JHE

### U(1) mixing and D-brane linear equivalence

Linear equivalence is a criterion that compares submanifolds in the same
homology class. We show that, in the context of type II compactifications with
D-branes, this concept translates to the kinetic mixing between U(1) gauge
symmetries arising in the open and closed string sectors. We argue that in
generic D-brane models such mixing is experimentally detectable through the
existence of milli-charged particles. We compute these gauge kinetic functions
by classifying the 4d monopoles of a compactification and analyzing the Witten
effect on them, finding agreement with previous results and extending them to
more general setups. In particular, we compute the gauge kinetic functions
mixing bulk and magnetized D-brane U(1)'s and derive a generalization of linear
equivalence for these objects. Finally, we apply our findings to F-theory SU(5)
models with hypercharge flux breaking.Comment: 43 pages+appendices, 1 figure; v2: typos corrected and references
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### Supersymmetric Casimir Energy and $\mathrm{SL(3,\mathbb{Z})}$ Transformations

We provide a recipe to extract the supersymmetric Casimir energy of theories
defined on primary Hopf surfaces directly from the superconformal index. It
involves an $\mathrm{SL(3,\mathbb{Z})}$ transformation acting on the complex
structure moduli of the background geometry. In particular, the known relation
between Casimir energy, index and partition function emerges naturally from
this framework, allowing rewriting of the latter as a modified elliptic
hypergeometric integral. We show this explicitly for $\mathcal{N}=1$ SQCD and
$\mathcal{N}=4$ supersymmetric Yang-Mills theory for all classical gauge
groups, and conjecture that it holds more generally. We also use our method to
derive an expression for the Casimir energy of the nonlagrangian
$\mathcal{N}=2$ SCFT with $\mathrm{E_6}$ flavour symmetry. Furthermore, we
predict an expression for Casimir energy of the $\mathcal{N}=1$
$\mathrm{SP(2N)}$ theory with $\mathrm{SU(8)\times U(1)}$ flavour symmetry that
is part of a multiple duality network, and for the doubled $\mathcal{N}=1$
theory with enhanced $\mathrm{E}_7$ flavour symmetry.Comment: 20 pages, more explicit examples added, published in JHE

### Chiral anomalies on a circle and their cancellation in F-theory

We study in detail how four-dimensional local anomalies manifest themselves
when the theory is compactified on a circle. By integrating out the
Kaluza-Klein modes in a way that preserves the four-dimensional symmetries in
the UV, we show that the three-dimensional theory contains field-dependent
Chern-Simons terms that appear at one-loop. These vanish if and only if the
four-dimensional anomaly is canceled, so the anomaly is not lost upon
compactification. We extend this analysis to situations where anomalies are
canceled through a Green-Schwarz mechanism. We then use these results to show
automatic cancellation of local anomalies in F-theory compactifications that
can be obtained as a limit of M-theory on a smooth Calabi-Yau fourfold with
background flux.Comment: 39 pages, 3 figures. v2: references added and typos correcte

### IIB flux non-commutativity and the global structure of field theories

We discuss the origin of the choice of global structure for six dimensional (2, 0) theories and their compactifications in terms of their realization from IIB string theory on ALE spaces. We find that the ambiguity in the choice of global structure on the field theory side can be traced back to a subtle effect that needs to be taken into account when specifying boundary conditions at infinity in the IIB orbifold, namely the known non-commutativity of RR fluxes in spaces with torsion. As an example, we show how the classification of N = 4 theories by Aharony, Seiberg and Tachikawa can be understood in terms of choices of boundary conditions for RR fields in IIB. Along the way we encounter a formula for the fractional instanton number of N = 4 ADE theories in terms of the torsional linking pairing for rational homology spheres. We also consider six-dimensional (1, 0) theories, clarifying the rules for determining commutators of flux operators for discrete 2-form symmetries. Finally, we analyze the issue of global structure for four dimensional theories in the presence of duality defects

### 2d orbifolds with exotic supersymmetry

We analyse various two dimensional theories arising from compactification of type II and heterotic string theory on asymmetric orbifolds. We find extra supersymmetry generators arising from twisted sectors, giving rise to exotic supersymmetry algebras. Among others we discover new cases with a large number of supercharges, such as N = (20, 8), N = (24, 8), N = (32, 0), N = (24, 24) and N = (48, 0)

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