Nothing is certain in string compactifications

Abstract A bubble of nothing is a spacetime instability where a compact dimension collapses. After nucleation, it expands at the speed of light, leaving “nothing” behind. We argue that the topological and dynamical mechanisms which could protect a compactification against decay to nothing seem to be absent in string compactifications once supersymmetry is broken. The topological obstruction lies in a bordism group and, surprisingly, it can disappear even for a SUSY-compatible spin structure. As a proof of principle, we construct an explicit bubble of nothing for a T3 with completely periodic (SUSY-compatible) spin structure in an Einstein dilaton Gauss-Bonnet theory, which arises in the low-energy limit of certain heterotic and type II flux compactifications. Without the topological protection, supersymmetric compactifications are purely stabilized by a Coleman-deLuccia mechanism, which relies on a certain local energy condition. This is violated in our example by the nonsupersymmetric GB term. In the presence of fluxes this energy condition gets modified and its violation might be related to the Weak Gravity Conjecture.We expect that our techniques can be used to construct a plethora of new bubbles of nothing in any setup where the low-energy bordism group vanishes, including type II compactifications on CY3, AdS flux compactifications on 5-manifolds, and M-theory on 7-manifolds. This lends further evidence to the conjecture that any non-supersymmetric vacuum of quantum gravity is ultimately unstable.

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Universal axion backreaction in flux compactifications

Journal of High Energy Physics ◽

10.1007/jhep06(2021)067 ◽

2021 ◽

Vol 2021 (6) ◽

Author(s):

Thomas W. Grimm ◽

Chongchuo Li

Keyword(s):

Flux Compactifications ◽

Complex Structure ◽

Boundary Structure ◽

Type Ii ◽

Newton Polygons ◽

String Compactifications ◽

Axion Field ◽

Field Excursion ◽

Scalar Potentials ◽

Puiseux Expansions

Abstract We study the backreaction effect of a large axion field excursion on the saxion partner residing in the same $$ \mathcal{N} $$ N = 1 multiplet. Such configurations are relevant in attempts to realize axion monodromy inflation in string compactifications. We work in the complex structure moduli sector of Calabi-Yau fourfold compactifications of F-theory with four-form fluxes, which covers many of the known Type II orientifold flux compactifications. Noting that axions can only arise near the boundary of the moduli space, the powerful results of asymptotic Hodge theory provide an ideal set of tools to draw general conclusions without the need to focus on specific geometric examples. We find that the boundary structure engraves a remarkable pattern in all possible scalar potentials generated by background fluxes. By studying the Newton polygons of the extremization conditions of all allowed scalar potentials and realizing the backreaction effects as Puiseux expansions, we find that this pattern forces a universal backreaction behavior of the large axion field on its saxion partner.

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Low-energy supersymmetry breaking from string flux compactifications: Benchmark scenarios

Journal of High Energy Physics ◽

10.1088/1126-6708/2006/04/040 ◽

2006 ◽

Vol 2006 (04) ◽

pp. 040-040 ◽

Cited By ~ 20

Author(s):

Benjamin C Allanach ◽

Fernando Quevedo ◽

Kerim Suruliz

Keyword(s):

Flux Compactifications ◽

Supersymmetry Breaking ◽

Low Energy

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Explicit soft supersymmetry breaking in the heterotic M-theory B − L MSSM

Journal of High Energy Physics ◽

10.1007/jhep08(2021)033 ◽

2021 ◽

Vol 2021 (8) ◽

Author(s):

Anthony Ashmore ◽

Sebastian Dumitru ◽

Burt A. Ovrut

Keyword(s):

Line Bundle ◽

Supersymmetry Breaking ◽

Moduli Space ◽

Initial Conditions ◽

Low Energy ◽

Strongly Coupled ◽

Hidden Sector ◽

Effective Lagrangian ◽

Soft Supersymmetry Breaking ◽

M Theory

Abstract The strongly coupled heterotic M-theory vacuum for both the observable and hidden sectors of the B − L MSSM theory is reviewed, including a discussion of the “bundle” constraints that both the observable sector SU(4) vector bundle and the hidden sector bundle induced from a single line bundle must satisfy. Gaugino condensation is then introduced within this context, and the hidden sector bundles that exhibit gaugino condensation are presented. The condensation scale is computed, singling out one line bundle whose associated condensation scale is low enough to be compatible with the energy scales available at the LHC. The corresponding region of Kähler moduli space where all bundle constraints are satisfied is presented. The generic form of the moduli dependent F-terms due to a gaugino superpotential — which spontaneously break N = 1 supersymmetry in this sector — is presented and then given explicitly for the unique line bundle associated with the low condensation scale. The moduli-dependent coefficients for each of the gaugino and scalar field soft supersymmetry breaking terms are computed leading to a low-energy effective Lagrangian for the observable sector matter fields. We then show that at a large number of points in Kähler moduli space that satisfy all “bundle” constraints, these coefficients are initial conditions for the renormalization group equations which, at low energy, lead to completely realistic physics satisfying all phenomenological constraints. Finally, we show that a substantial number of these initial points also satisfy a final constraint arising from the quadratic Higgs-Higgs conjugate soft supersymmetry breaking term.

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Leptogenesis and low-energy CP violation in a type-II-dominated left-right seesaw model

Nuclear Physics B ◽

10.1016/j.nuclphysb.2021.115552 ◽

2021 ◽

pp. 115552

Author(s):

Thomas Rink ◽

Werner Rodejohann ◽

Kai Schmitz

Keyword(s):

Cp Violation ◽

Low Energy ◽

Type Ii ◽

Seesaw Model

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On TCS G2 manifolds and 4D emergent strings

Journal of High Energy Physics ◽

10.1007/jhep10(2020)045 ◽

2020 ◽

Vol 2020 (10) ◽

Author(s):

Fengjun Xu

Keyword(s):

Moduli Space ◽

Quantum Corrections ◽

Type Ii ◽

Quantum Level ◽

Weakly Coupled ◽

G2 Manifolds ◽

Fundamental Type ◽

M Theory ◽

Distance Limit ◽

Refined Version

Abstract In this note, we study the Swampland Distance Conjecture in TCS G2 manifold compactifications of M-theory. In particular, we are interested in testing a refined version — the Emergent String Conjecture, in settings with 4d N = 1 supersymmetry. We find that a weakly coupled, tensionless fundamental heterotic string does emerge at the infinite distance limit characterized by shrinking the K3-fiber in a TCS G2 manifold. Such a fundamental tensionless string leads to the parametrically leading infinite tower of asymptotically massless states, which is in line with the Emergent String Conjecture. The tensionless string, however, receives quantum corrections. We check that these quantum corrections do modify the volume of the shrinking K3-fiber via string duality and hence make the string regain a non-vanishing tension at the quantum level, leading to a decompactification. Geometrically, the quantum corrections modify the metric of the classical moduli space and are expected to obstruct the infinite distance limit. We also comment on another possible type of infinite distance limit in TCS G2 compactifications, which might lead to a weakly coupled fundamental type II string theory.

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EXTREME DYONIC BLACK HOLES IN STRING THEORY

Modern Physics Letters A ◽

10.1142/s0217732396000709 ◽

1996 ◽

Vol 11 (09) ◽

pp. 689-713 ◽

Cited By ~ 152

Author(s):

A.A. TSEYTLIN

Keyword(s):

Black Holes ◽

String Theory ◽

Short Distance ◽

Black Hole Entropy ◽

Universal Relation ◽

Type Ii ◽

Statistical Entropy ◽

Five Dimensions ◽

Compact Dimension ◽

Lower Dimensional

Supersymmetric extreme dyonic black holes of toroidally compactified heterotic or type-II string theory can be viewed as lower-dimensional images of solitonic strings wound around a compact dimension. We consider conformal sigma models which describe string configurations corresponding to various extreme dyonic black holes in four and five dimensions. These conformal models have regular short-distance region equivalent to a WZW theory with level proportional to magnetic charges. Arguments are presented suggesting a universal relation between the black hole entropy (area) and the statistical entropy of BPS-saturated oscillation states of solitonic string.

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