Jakub Vosmera

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Vosmera

First Name

Jakub

ORCID

0000-0002-1690-6072

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Publications 1 - 8 of 8

The nilpotent structure of open-closed string field theory
Maccaferri, Carlo; Ruffino, Alberto; Vosmera, Jakub (2023)
Journal of High Energy Physics
In this note we revisit the homotopy-algebraic structure of oriented bosonic open-closed string field theory and we give a new compact formulation in terms of a single cyclic open-closed co-derivation which defines a single nilpotent structure describing the consistency of generic open-closed off-shell amplitudes with arbitrary number of boundaries and at arbitrary genus.
Closed string deformations in open string field theory. Part III. N = 2 worldsheet localization
Maccaferri, Carlo; Vosmera, Jakub (2021)
Journal of High Energy Physics
In this paper, which is the last of a series including [1, 2] we first verify that the two open-closed effective potentials derived in the previous paper from the WZW theory in the large Hilbert space and the A(infinity) theory in the small Hilbert space have the same vacuum structure. In particular, we show that mass-term deformations given by the effective (open)(2)-closed couplings are the same, provided the effective tadpole is vanishing to first order in the closed string deformation. We show that this condition is always realized when the worldsheet BCFT enjoys a global N = 2 superconformal symmetry and the deforming closed string belongs to the chiral ring in both the holomorphic and anti-holomorphic sector. In this case it is possible to explicitly evaluate the mass deformation by localizing the SFT Feynman diagrams to the boundary of world-sheet moduli space, reducing the amplitude to a simple open string two-point function. As a non-trivial check of our construction we couple a constant Kalb-Ramond closed string state to the OSFT on the D3-D( -1) system and we show that half of the bosonic blowing-up moduli become tachyonic, making the system condense to a bound state whose binding energy we compute exactly to second order in the closed string deformation, finding agreement with the literature.
Closed string deformations in open string field theory. Part I. Bosonic string
Maccaferri, Carlo; Vosmera, Jakub (2021)
Journal of High Energy Physics
This is the first of a series of three papers on open string field theories based on Witten star product deformed with a gauge invariant open/closed coupling. This de- formation is a tree-level tadpole which destabilizes the initial perturbative vacuum. We discuss the existence of vacuum-shift solutions which cancel the tadpole and represent a new configuration where the initial D-brane system has adapted to the change in the closed string background. As an example we consider the bulk deformation which changes the compactification radius and, to first order in the deformation, we reproduce the shift in the mass of the open string KK modes from the new kinetic operator after the vacuum shift. We also discuss the possibility of taming closed string degenerations with the open string propagator in the simplest amplitude corresponding to two closed strings off a disk.
Topological defects and tensionless holography
Knighton, Bob; Sriprachyakul, Vit; Vosmera, Jakub (2025)
Journal of High Energy Physics
We study topological defect lines in the symmetric-product orbifolds SymN(X) for a generic seed CFT X. We focus on the defects which preserve the maximum of the SN symmetry. When X is taken to describe the free theory of four fermions and four bosons on a T4, we construct holographically dual backgrounds describing propagation of tensionless closed strings in the presence of spacetime defects wrapping the conformal boundary. We find a precise match between the spectra of local on-shell closed-string vertex operators in the bulk and the spectra of non-local disorder fields in the spacetime theory.
Open-closed string field theory in the large N limit
Maccaferri, Carlo; Ruffino, Alberto; Vosmera, Jakub (2023)
Journal of High Energy Physics
We use the new nilpotent formulation of open-closed string field theory to explore the limit where the number N of identical D-branes of the starting background is large. By reformulating the theory in terms of the ’t Hooft coupling λ := κN, where κ is the string coupling constant, we explicitly see that at large N only genus zero vertices with arbitrary number of boundaries survive. After discussing the homotopy structure of the obtained large N open-closed theory we discuss the possibility of integrating out the open string sector with a quantum but planar homotopy transfer. As a result we end up with a classical closed string field theory, described by a weak L∞-algebra containing a tree-level tadpole which, to first order in λ, is given by the initial boundary state. We discuss the possibility of removing the tadpole with a closed string vacuum shift solution, to end up with a new classical closed string background, where the initial D-branes have been turned into pure closed-string backreaction.
D-branes in AdS₃ x S³ x 𝕋⁴ at k = 1 and their holographic duals
Gaberdiel, Matthias; Knighton, Bob; Vosmera, Jakub (2021)
Journal of High Energy Physics
String theory on AdS₃ × S³ × 𝕋⁴ with minimal k = 1 NS-NS flux can be described in terms of a free field worldsheet theory in the hybrid formalism. We construct various D-branes of this string theory and calculate their associated cylinder amplitudes. We find that these amplitudes match with the cylinder correlators of certain boundary states of the dual symmetric orbifold CFT Sym(𝕋⁴), thus suggesting a direct correspondence between these boundary conditions. We also show that the disk amplitudes of these D-branes localise to those points in the worldsheet moduli space where the worldsheet disk holomorphically covers the spacetime disk.
Closed string deformations in open string field theory. Part II. Superstring
Maccaferri, Carlo; Vosmera, Jakub (2021)
Journal of High Energy Physics
This is the second paper of a series of three. We construct effective open-closed superstring couplings by classically integrating out massive fields from open superstring field theories coupled to an elementary gauge invariant tadpole proportional to an on-shell closed string state in both large and small Hilbert spaces, in the NS sector. This source term is well known in the WZW formulation and by explicitly performing a novel large Hilbert space perturbation theory we are able to characterize the first orders of the vacuum shift solution, its obstructions and the non-trivial open-closed effective couplings in closed form. With the aim of getting all order results, we also construct a new observable in the A∞ theory in the small Hilbert space which correctly provides a gauge invariant coupling to physical closed strings and which descends from the WZW open-closed coupling upon partial gauge fixing and field redefinition. Armed with this new A∞ observable we use tensor co-algebra techniques to efficiently package the whole perturbation theory necessary for computing the effective action and we give all order results for the open-closed effective couplings in the small Hilbert space.
The classical cosmological constant of open-closed string field theory
Maccaferri, Carlo; Vosmera, Jakub (2022)
Journal of High Energy Physics
We consider deformations of D-brane systems induced by a change in the closed string background in the framework of bosonic open-closed string field theory, where it is possible to unambiguously tame infrared divergences originating from both open and closed string degenerations. A closed string classical solution induces a tadpole for the open strings which shifts the open string vacuum and generates a cosmological constant composed of two terms: one which is directly related to the closed string solution and the other which depends on the open string vacuum shift. We show that only the sum of these two terms is invariant under closed SFT gauge transformations and therefore is an observable. We conjecture that this observable is universally proportional to the shift in the world-sheet disk partition function between the starting D-brane in undeformed background and the final D-brane in deformed background, which typically includes also a change in the string coupling constant. We test the conjecture by considering a perturbative closed string solution describing deformations of a Narain compactification and, from the SFT cosmological constant, we reproduce the expected shift in the g-function of various D-branes living in the compactification. In doing this we are also able to identify a surprising change in the string coupling constant at second order in the deformation.

Publications 1 - 8 of 8

Jakub Vosmera

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