Thraxions: ultralight throat axions
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Springer
Received: January Revised: March Accepted: April Published: April
18, 26, 18, 29,
2019 2019 2019 2019
Thraxions: ultralight throat axions
a
Institute for Theoretical Physics, University of Heidelberg, Philosophenweg 19, 69120 Heidelberg, Germany b Deutsches Elektronen-Synchrotron, DESY, Notkestraße 85, 22607 Hamburg, Germany
E-mail: [email protected], [email protected], [email protected], [email protected] Abstract: We argue that a new type of extremely light axion is generically present in the type IIB part of the string theory landscape. Its mass is suppressed by the third power of the warp factor of a strongly warped region (Klebanov-Strassler throat), suggesting the name thraxion. Our observation is based on the generic presence of several throats sharing the same 2-cycle. This cycle shrinks to zero volume at the end of each throat. It is hence trivial in homology and the corresponding C2 axion is massive. However, the mass is warpingsuppressed since, if one were to cut off the strongly warped regions, a proper 2-cycle would re-emerge. Since the kinetic term of the axion is dominated in the UV, an even stronger, quadratic mass suppression results. Moreover, if the axion is excited, the angular modes of the throats backreact. This gives our effective C2 axion a finite monodromy and flattens its potential even further. Eventually, the mass turns out to scale as the third power of the warp factor. We briefly discuss possible implications for phenomenology and potential violations of the Weak Gravity Conjecture for axions. Moreover we identify a mechanism for generating super-Planckian axionic field ranges which we call drifting monodromies. However, in the examples we consider, the potential oscillates on sub-Planckian distances in field space, preventing us from building a natural inflation model on the basis of this idea. Keywords: Strings and branes phenomenology ArXiv ePrint: 1812.03999
c The Authors. Open Access, Article funded by SCOAP3 .
https://doi.org/10.1007/JHEP04(2019)158
JHEP04(2019)158
Arthur Hebecker,a Sascha Leonhardt,a Jakob Moritzb and Alexander Westphalb
Contents 1 Introduction
2 4 4 4 6 8 9 11 13
3 Four-dimensional SUGRA completion 3.1 Counting moduli through the conifold transition 3.2 The thraxion superpotential 3.2.1 The GVW superpotential of a multi conifold system 3.2.2 The thraxion as a stabilizer field 3.2.3 The double throat: n = 2, m = 1 3.2.4 The general multi throat 3.3 Comments on the b-Axion
14 15 16 16 17 19 21 22
4 The axion potential and the gauge/gravity correspondence
23
5 Applications 5.1 Thraxions on the quintic: drifting monodromy 5.2 A clash with the weak gravity conjecture 5.3 The spectrum of effective instantons 5.4 Axion phenomenology 5.5 Uplifting
24 24 26 28 29 29
6 Conclusion and discussion
31
A Deformed conifold for general complex structure modulus
33
B The axion potential in the local throat
36
C Derivation and solution of the 5d equations of motion C.1 The 5d action for ϕ C.2 Schr¨ odinger equati
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