scholarly journals Universal axion backreaction in flux compactifications

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.

scholarly journals Nothing is certain in string compactifications

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Iñaki García Etxebarria ◽  
Miguel Montero ◽  
Kepa Sousa ◽  
Irene Valenzuela
Keyword(s):  
Flux Compactifications ◽  
Spin Structure ◽  
Energy Condition ◽  
Low Energy ◽  
Type Ii ◽  
String Compactifications ◽  
Compact Dimension ◽  
Bordism Group ◽  
Topological Obstruction ◽  
M Theory

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.

scholarly journals Weak gravity bounds in asymptotic string compactifications

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Brice Bastian ◽  
Thomas W. Grimm ◽  
Damian van de Heisteeg
Keyword(s):  
Black Holes ◽  
Moduli Space ◽  
Mass Formula ◽  
Complex Structure ◽  
Mass Ratio ◽  
De Sitter ◽  
String Compactifications ◽  
Type Iib String Theory ◽  
Bps States ◽  
Weak Gravity

Abstract We study the charge-to-mass ratios of BPS states in four-dimensional $$ \mathcal{N} $$ N = 2 supergravities arising from Calabi-Yau threefold compactifications of Type IIB string theory. We present a formula for the asymptotic charge-to-mass ratio valid for all limits in complex structure moduli space. This is achieved by using the sl(2)-structure that emerges in any such limit as described by asymptotic Hodge theory. The asymptotic charge-to-mass formula applies for sl(2)-elementary states that couple to the graviphoton asymptotically. Using this formula, we determine the radii of the ellipsoid that forms the extremality region of electric BPS black holes, which provides us with a general asymptotic bound on the charge-to-mass ratio for these theories. Finally, we comment on how these bounds for the Weak Gravity Conjecture relate to their counterparts in the asymptotic de Sitter Conjecture and Swampland Distance Conjecture.

scholarly journals ON ISSUES IN SWISS CHEESE COMPACTIFICATIONS

2008 ◽  
Vol 23 (36) ◽  
pp. 3031-3047 ◽  
Author(s):  
AALOK MISRA
Keyword(s):  
Inverse Problem ◽  
Black Holes ◽  
Flux Compactifications ◽  
Large Volume ◽  
Type Ii ◽  
Swiss Cheese ◽  
Slow Roll ◽  
Slow Roll Inflation

We give a brief review of our previous works.1,2 We discuss two sets of issues. The first has to do with the possibility of getting a non-supersymmetric dS minimum without the addition of [Formula: see text]-branes as in KKLT, and axionic slow-roll inflation, in type II flux compactifications. The second has to do with the "Inverse Problem"3 and "Fake Superpotentials"4 for extremal (non)supersymmetric black holes in type II compactifications. We use (orientifold of) a "Swiss Cheese" Calabi–Yau5 expressed as a degree-18 hypersurface in WCP4[1, 1, 1, 6, 9] in the "large-volume-scenario" limit6 for the former.

scholarly journals Self-dual nonsupersymmetric type II string compactifications

1998 ◽  
Vol 1998 (11) ◽  
pp. 001-001 ◽  
Author(s):  
Shamit Kachru ◽  
Eva Silverstein
Keyword(s):  
Type Ii ◽  
String Compactifications

scholarly journals Landscape of modular symmetric flavor models

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Keiya Ishiguro ◽  
Tatsuo Kobayashi ◽  
Hajime Otsuka
Keyword(s):  
Fixed Point ◽  
Flux Compactifications ◽  
Strong Correlation ◽  
Complex Structure ◽  
Fundamental Region ◽  
Moduli Stabilization ◽  
Flavor Symmetries ◽  
Flavor Structure ◽  
String Landscape

Abstract We study the moduli stabilization from the viewpoint of modular flavor symmetries. We systematically analyze stabilized moduli values in possible configurations of flux compactifications, investigating probabilities of moduli values and showing which moduli values are favorable from our moduli stabilization. Then, we examine their implications on modular symmetric flavor models. It is found that distributions of complex structure modulus τ determining the flavor structure are clustered at a fixed point with the residual ℤ3 symmetry in the SL(2, ℤ) fundamental region. Also, they are clustered at other specific points such as intersecting points between |τ|2 = k/2 and Re τ = 0,±1/4,±1/2, although their probabilities are less than the ℤ3 fixed point. In general, CP-breaking vacua in the complex structure modulus are statistically disfavored in the string landscape. Among CP-breaking vacua, the values Re τ = ±1/4 are most favorable in particular when the axio-dilaton S is stabilized at Re S = ±1/4. That shows a strong correlation between CP phases originated from string moduli.

scholarly journals Recent Progress in the Physics of Axions and Axion-Like Particles

2021 ◽  
Vol 71 (1) ◽  
Author(s):  
Kiwoon Choi ◽  
Sang Hui Im ◽  
Chang Sub Shin
Keyword(s):  
Recent Progress ◽  
Model Building ◽  
Formal Theory ◽  
Annual Review ◽  
Model Parameters ◽  
Publication Date ◽  
Axion Field ◽  
Wide Range ◽  
Pseudoscalar Particle ◽  
Field Excursion

The axion is a light pseudoscalar particle postulated to solve issues with the Standard Model, including the strong CP problem and the origin of dark matter. In recent years, there has been remarkable progress in the physics of axions in several directions. An unusual type of axion-like particle termed the relaxion was proposed as a new solution to the weak scale hierarchy problem. There are also new ideas for laboratory, astrophysical, or cosmological searches for axions; such searches can probe a wide range of model parameters that were previously inaccessible. On the formal theory side, the weak gravity conjecture indicates a tension between quantum gravity and a trans-Planckian axion field excursion. Many of these developments involve axions with hierarchical couplings. In this article, we review recent progress in axion physics, with particular attention paid to hierarchies between axion couplings. We emphasize that the parameter regions of hierarchical axion couplings are the most accessible experimentally. Moreover, such regions are often where important theoretical questions in the field are addressed, and they can result from simple model-building mechanisms. Expected final online publication date for the Annual Review of Nutrition, Volume 41 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

scholarly journals From Type II string theory toward BSM/dark sector physics

2016 ◽  
Vol 31 (34) ◽  
pp. 1630050 ◽  
Author(s):  
Gabriele Honecker
Keyword(s):  
String Theory ◽  
Open String ◽  
New Physics ◽  
Closed String ◽  
Type Ii ◽  
Dark Sector ◽  
Four Dimensions ◽  
Brane Model ◽  
Moduli Stabilization ◽  
String Compactifications

Four-dimensional compactifications of string theory provide a controlled set of possible gauge representations accounting for BSM particles and dark sector components. In this review, constraints from perturbative Type II string compactifications in the geometric regime are discussed in detail and then compared to results from heterotic string compactifications and nonperturbative/nongeometric corners. As a prominent example, an open string realization of the QCD axion is presented. The status of deriving the associated low-energy effective action in four dimensions is discussed and open avenues of major phenomenological importance are highlighted. As examples, a mechanism of closed string moduli stabilization by D-brane backreaction as well as one-loop threshold corrections to the gauge couplings and balancing a low string scale [Formula: see text] with unisotropic compact dimensions are discussed together with implications on potential future new physics observations. For illustrative purposes, an explicit example of a globally consistent D6-brane model with MSSM-like spectrum on [Formula: see text] is presented.

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