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Erler Jens | Erler J. | Erler Theodore | Erler Theodore G. | Erler Frido | Erler Martin | Erler B. | Erler Bastian | Erler F. | Erler Nicole S.

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Four Lectures on Analytic Solutions in Open String Field Theory

Erler Theodore
01 Dec 2019 hep-th arxiv.org/abs/1912.00521

The following notes derive from review lectures on the subject of analytic solutions in open string field theory, given at the School for String Field Theory and String Phenomenology at the Harish-Chandra Research Institute in February 2018.

String Field Theory Solution for Any Open String Background. II

Erler Theodore, Maccaferri Carlo
25 Sep 2019 hep-th arxiv.org/abs/1909.11675

Generalizing previous work, we give a new analytic solution in Witten's open bosonic string field theory which can describe any open string background. The central idea is to use Riemann surface degenerations as a mechanism for taming OPE singularities. This requires leaving the familiar subalgebra of wedge states with insertions, but the payoff is that the solution makes no assumptions about the reference and target D-brane systems, and is therefore truly general. For example, unlike in previous work, the solution can describe time dependent backgrounds and multiple copies of the reference D-brane within the universal sector. The construction also resolves some subtle issues resulting from associativity anomalies, giving a more complete understanding of the relation between the degrees of freedom of different D-brane systems, and a nonperturbative proof of background independence in classical open bosonic string field theory.

Four Lectures on Closed String Field Theory

Erler Theodore
16 May 2019 hep-th arxiv.org/abs/1905.06785

The following notes derive from review lectures on closed string field theory given at the Galileo Galilei Institute for Theoretical Physics in March 2019.

Rolling Near the Tachyon Vacuum

Erler Theodore, Masuda Toru, Schnabl Martin
28 Feb 2019 hep-th arxiv.org/abs/1902.11103

In a linear dilaton background, it has been argued that an unstable D-brane can decay to the tachyon vacuum without leaving behind a remnant of tachyon matter. Here we address the question of how the D-brane can decay to the tachyon vacuum when the tachyon vacuum does not support physical fluctuations. Using the formalism of open string field theory, we find that the tachyon vacuum {\it can} support fluctuations provided they are "hidden" as nonperturbative effects behind a pure gauge asymptotic series.

Taming boundary condition changing operator anomalies with the tachyon vacuum

Erler Theodore, Maccaferri Carlo, Noris Ruggero
23 Jan 2019 hep-th arxiv.org/abs/1901.08038

Motivated by the appearance of associativity anomalies in the context of superstring field theory, we give a generalized solution built from boundary condition changing operators which can be associated to a generic tachyon vacuum in the $KBc$ subalgebra of the Okawa form. We articulate sufficient conditions on the choice of tachyon vacuum to ensure that ambiguous products do not appear in the equations of motion.

Vertical Integration from the Large Hilbert Space

Erler Theodore, Konopka Sebastian
19 Oct 2017 hep-th arxiv.org/abs/1710.07232

We develop an alternative description of the procedure of vertical integration based on the observation that amplitudes can be written in BRST exact form in the large Hilbert space. We relate this approach to the description of vertical integration given by Sen and Witten.

Superstring Field Theory and the Wess-Zumino-Witten Action

Erler Theodore
08 Jun 2017 hep-th math.QA arxiv.org/abs/1706.02629

We describe a notion of "higher" Wess-Zumino-Witten-like action which is natural in the context of superstring field theories formulated in the large Hilbert space. For the open string, the action is characterized by a pair of commuting cyclic $A_\infty$ structures together with a hierarchy of higher-form potentials analogous to the Maurer-Cartan elements which appear in the conventional Wess-Zumino-Witten action. We apply this formalism to get a better understanding of symmetries of open superstring field theory and the structure of interactions in the Ramond sector, describing an interesting connection between Ramond vertices and Feynman diagrams.

One Loop Tadpole in Heterotic String Field Theory

Erler Theodore, Konopka Sebastian, Sachs Ivo
04 Apr 2017 hep-th arxiv.org/abs/1704.01210

We compute the off-shell 1-loop tadpole amplitude in heterotic string field theory. With a special choice of cubic vertex, we show that this amplitude can be computed exactly. We obtain explicit and elementary expressions for the Feynman graph decomposition of the moduli space, the local coordinate map at the puncture as a function of the modulus, and the $b$-ghost insertions needed for the integration measure. Recently developed homotopy algebra methods provide a consistent configuration of picture changing operators. We discuss the consequences of spurious poles for the choice of picture changing operators.

Supersymmetry in Open Superstring Field Theory

Erler Theodore
11 Oct 2016 hep-th arxiv.org/abs/1610.03251

We realize the 16 unbroken supersymmetries on a BPS D-brane as invariances of the action of the corresponding open superstring field theory. We work in the small Hilbert space approach, where a symmetry of the action translates into a symmetry of the associated cyclic $A_\infty$ structure. We compute the supersymmetry algebra, being careful to disentangle the components which produce a translation, a gauge transformation, and a symmetry transformation which vanishes on-shell. Via the minimal model theorem, we illustrate how supersymmetry of the action implies supersymmetry of the tree level open string scattering amplitudes.

Complete Action for Open Superstring Field Theory with Cyclic $A_\infty$ Structure

Erler Theodore, Okawa Yuji, Takezaki Tomoyuki
08 Feb 2016 hep-th arxiv.org/abs/1602.02582

We construct a gauge invariant action for the Neveu-Schwarz and Ramond sectors of open superstring field theory realizing a cyclic $A_\infty$ structure, providing the first complete and fully explicit solution to the classical Batalin-Vilkovisky master equation in superstring field theory. We also demonstrate the equivalence of our action to the Wess-Zumino-Witten-based construction of Kunitomo and one of the authors.