Spacetime instanton corrections in 4D string vacua: The seesaw mechanism for D-brane models

Blumenhagen, Ralph; Cvetič, Mirjam; Weigand, Timo

doi:10.1016/j.nuclphysb.2007.02.016

Cited by 348 publications

(798 citation statements)

References 70 publications

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“…In the latter, Majorana neutrino masses may in principle appear from string instanton effects [46,47]. However, a dedicated search [48] for such instanton effects in a large class of MSSM-like Gepner orientifolds was unsuccesful.…”

Section: Jhep06(2018)051mentioning

confidence: 99%

AdS-phobia, the WGC, the Standard Model and Supersymmetry

Gonzalo

Herráez

Ibáñez

2018

J. High Energ. Phys.

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It has been recently argued that an embedding of the SM into a consistent theory of quantum gravity may imply important constraints on the mass of the lightest neutrino and the cosmological constant Λ 4 . The constraints come from imposing the absence of any non-SUSY AdS stable vacua obtained from any consistent compactification of the SM to 3 or 2 dimensions. This condition comes as a corollary of a recent extension of the Weak Gravity Conjecture (WGC) by Ooguri and Vafa. In this paper we study T 2 /Z N compactifications of the SM to two dimensions in which SM Wilson lines are projected out, leading to a considerable simplification. We analyze in detail a T 2 /Z 4 compactification of the SM in which both complex structure and Wilson line scalars are fixed and the potential is only a function of the area of the torus a 2 . We find that the SM is not robust against the appearance of AdS vacua in 2D and hence would be by itself inconsistent with quantum gravity. On the contrary, if the SM is embedded at some scale M SS into a SUSY version like the MSSM, the AdS vacua present in the non-SUSY case disappear or become unstable. This means that WGC arguments favor a SUSY version of the SM, independently of the usual hierarchy problem arguments. In a T 2 /Z 4 compactification in which the orbifold action is embedded into the B − L symmetry the bounds on neutrino masses and the cosmological constant are recovered. This suggests that the MSSM should be extended with a U(1) B−L gauge group. In other families of vacua the spectrum of SUSY particles is further constrained in order to avoid the appearance of new AdS vacua or instabilities. We discuss a possible understanding of the little hierarchy problem in this context.

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Section: Jhep06(2018)051mentioning

confidence: 99%

AdS-phobia, the WGC, the Standard Model and Supersymmetry

Gonzalo

Herráez

Ibáñez

2018

J. High Energ. Phys.

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“…Examples of such couplings include yukawa couplings, the µ parameter, majorana mass terms for neutrinos and certain non-renormalizable operators [25]. In this work, we will primarily be interested in righthanded neutrino majorana masses and the B − L violating "Weinberg" operator leading to neutrino masses.…”

Section: U(1) S Anomalies Gauge Invariance and Brane Instantonsmentioning

confidence: 99%

“…The fermionic zero modes are much more important though. The uncharged (under the 4D gauge group) fermionic zero modes have to satisfy certain conditions to contribute to the superpotential [25]. We will focus on (chiral) charged fermionic zero modes which are much more interesting and relevant.…”

Section: U(1) S Anomalies Gauge Invariance and Brane Instantonsmentioning

confidence: 99%

“…In the explicit string constructions considered in [38], such examples were found in large number. 25 We will consider both cases where the instanton generating majorana masses dominates over the one generating the weinberg operator and vice versa, and argue that it is naturally possible to obtain the required value of (ĥ 2 λ ) in both cases. Also, since we are primarily interested in the baryon asymmetry, we will mostly focus on the lightest left-handed neutrino mass.…”

Section: Jhep05(2009)083mentioning

confidence: 99%

“…The detailed flavor structure is model-dependent; however some 25 Large number of models were found after satsifying a relaxed constraint on the symmetries of the instantons which can easily occur in the presence of fluxes [38].…”

Section: Jhep05(2009)083mentioning

confidence: 99%

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Neutrino masses, Baryon asymmetry, dark matter and the moduli problem — A complete framework

Kumar¹

2009

J. High Energy Phys.

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Neutrino masses, Baryon asymmetry, dark matter and the moduli problem -A complete framework E-mail: kpiyush@berkeley.eduAbstract: Recent developments in string theory have led to "realistic" string compactifications which lead to moduli stabilization while generating a hierarchy between the Electroweak and Planck scales at the same time. However, this seems to suggest a rethink of our standard notions of cosmological evolution after the end of inflation and before the beginning of BBN. This epoch is crucial for addressing the issues of neutrino masses, baryon asymmetry, Dark Matter (DM) abundance and the moduli (gravitino) problem. We argue that within classes of realistic string compactifications as defined above, there generically exists a light modulus with a mass comparable to that of the gravitino which is typically much smaller than the Hubble parameter during inflation. Therefore, it is destabilized and generates a large late-time entropy when it decays. Thus, all known elegant mechanisms of generating the baryon asymmetry of the Universe in the literature have to take this fact into account.In this work, we find that it is still possible to naturally generate the observed baryon asymmetry of the Universe as well as light left-handed neutrino masses from a period of Affleck-Dine (AD) leptogenesis shortly after the end of inflation, in classes of realistic string constructions with a minimal extension of the MSSM below the unification scale (consisting only of right-handed neutrinos) and satisfying certain microscopic criteria described in the text. The AD mechanism has already been used to generate the baryon asymmetry in the literature; however in this work we have embedded the above mechanism within a framework well motivated from string theory and have tried to describe the epoch from the end of inflation to the beginning of BBN in a complete and self-consistent manner. The consequences of our analysis are as follows. The lightest left-handed neutrino is required to be virtually massless. The moduli (gravitino) problem can be naturally solved in this framework both within gravity and gauge mediation. The observed upper bound on the relic abundance constrains the moduli-matter and moduli-gravitino couplings since the DM is produced non-thermally within this framework. Finally, although not a definite prediction, the framework naturally allows a light right-handed neutrino and sneutrinos around the electroweak scale which could have important implications for the nature of DM as well as the LHC.

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D‐brane instantons in 4D supersymmetric string vacua

Akerblom

Blumenhagen²,

Lüst

et al. 2008

Fortschritte der Physik

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We review some aspects of D-instantons in intersecting D-brane models. In particular, we present applications of the recently proposed instanton calculus to computations of charged matter superpotential couplings and corrections to the gauge kinetic function in the low energy effective action of type IIA orientifolds. As an interesting byway, we also discuss how one-loop corrections to the gauge kinetic function can be deduced from gauge threshold corrections in the type IIA setting.

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Spacetime instanton corrections in 4D string vacua: The seesaw mechanism for D-brane models

Cited by 348 publications

References 70 publications

AdS-phobia, the WGC, the Standard Model and Supersymmetry

AdS-phobia, the WGC, the Standard Model and Supersymmetry

Neutrino masses, Baryon asymmetry, dark matter and the moduli problem — A complete framework

D‐brane instantons in 4D supersymmetric string vacua

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