Irene Valenzuela

The inflaton as an MSSM Higgs and open string modulus monodromy inflation

Abstract It has been recently pointed out that high scale inflation, as recently hinted by the BICEP2 results, is consistent with the identification of an inflaton mass m I ≃ 10 13 GeV with the SUSY breaking scale in an MSSM with a fine-tuned SM Higgs. This identification leads to a Higgs mass m h ≃ 126 GeV , consistent with LHC measurements. Here we propose that this naturally suggests to identify the inflaton with the heavy MSSM Higgs system. The fact that the extrapolated Higgs coupling λ SM ≃ 0 at scales below the Planck scale suggests the Higgs degrees of freedom could be associated with a Wilson line or D-brane position modulus in string theory. The Higgs system then has a shift symmetry and an N = 2 structure which guarantees that its potential has an approximate quadratic chaotic inflation form. These moduli in string compactifications, being compact, allow for trans-Planckian inflaton field range analogous to a version of monodromy inflation.

Higgs-otic inflation and string theory

A bstractWe propose that inflation is driven by a (complex) neutral Higgs of the MSSM extension of the SM, in a chaotic-like inflation setting. The SUSY breaking soft term masses are of order 1012 − 1013 GeV, which is identified with the inflaton mass scale and is just enough to stabilise the SM Higgs potential. The fine-tuned SM Higgs has then a mass around 126 GeV, in agreement with LHC results. We point out that the required large field excursions of chaotic inflation may be realised in string theory with the (complex) inflaton/Higgs identified with a continuous Wilson line or D-brane position. We show specific examples and study in detail a IIB orientifold with D7-branes at singularities, with SM gauge group and MSSM Higgs sector. In this case the inflaton/Higgs fields correspond to D7-brane positions along a two-torus transverse to them. Masses and monodromy are induced by closed string G3 fluxes, and the inflaton potential can be computed directly from the DBI+CS action. We show how this action sums over Planck suppressed corrections, which amount to a field dependent rescaling of the inflaton fields, leading to a linear potential in the large field regime. We study the evolution of the two components of the Higgs/inflaton and compute the slow-roll parameters for purely adiabatic perturbations. For large regions of initial conditions slow roll inflation occurs and 50-60 efolds are obtained with r > 0.07, testable in forthcoming experiments. Our scheme is economical in the sense that both EWSB and inflation originate in the same sector of the theory, all inflaton couplings are known and reheating occurs efficiently.

The Higgs mass as a signature of heavy SUSY

A bstractWe compute the mass of the Higgs particle in a scheme in which SUSY is broken at a large scale MSS well above the electroweak scale MEW. Below MSS one assumes one is just left with the SM with a fine-tuned Higgs potential. Under standard unification assumptions one can compute the mass of the Higgs particle as a function of the SUSY breaking scale MSS. For MSS ≳ 1010 GeV one obtains mH = 126 ± 3 GeV, consistent with CMS and ATLAS results. For lower values of MSS the values of the Higgs mass tend to those of a fine-tuned MSSM with mH ≲ 130 GeV. These results support the idea that the measured value of the Higgs mass at LHC may be considered as indirect evidence for the existence of SUSY at some (not necessarily low) mass scale.

The Intermediate Scale MSSM, the Higgs Mass and F-theory Unification

A bstractEven if SUSY is not present at the Electro-Weak scale, string theory suggests its presence at some scale MSS below the string scale Ms to guarantee the absence of tachyons. We explore the possible value of MSS consistent with gauge coupling unification and known sources of SUSY breaking in string theory. Within F-theory SU(5) unification these two requirements fix MSS ≃ 5 × 1010 GeV at an intermediate scale and a unification scale Mc ≃ 3 × 1014 GeV. As a direct consequence one also predicts the vanishing of the quartic Higgs SM self-coupling at MSS ≃ 1011 GeV. This is tantalizingly consistent with recent LHC hints of a Higgs mass in the region 124-126 GeV. With such a low unification scale Mc ≃ 3 × 1014GeV one may worry about too fast proton decay via dimension 6 operators. However in the F-theory GUT context SU(5) is broken to the SM via hypercharge flux. We show that this hypercharge flux deforms the SM fermion wave functions leading to a suppression, avoiding in this way the strong experimental proton decay constraints. In these constructions there is generically an axion with a scale of size fa ≃ Mc/(4π)2 ≃ 1012 GeV which could solve the strong CP problem and provide for the observed dark matter. The price to pay for these attractive features is to assume that the hierarchy problem is solved due to anthropic selection in a string landscape.

Special points of inflation in flux compactifications

We study the realization of axion inflation models in the complex structure moduli spaces of Calabi–Yau threefolds and fourfolds. The axions arise close to special points of these moduli spaces that admit discrete monodromy symmetries of infinite order. Examples include the large complex structure point and conifold point, but can be of more general nature. In Type IIB and F-theory compactifications the geometric axions receive a scalar potential from a flux-induced superpotential. We find toy variants of various inflationary potentials including the ones for natural inflation of one or multiple axions, or axion monodromy inflation with polynomial potential. Interesting examples are also given by mirror geometries of torus fibrations with Mordell–Weil group of rank N − 1o r an N-section, which admit an axion if N> 3.

Minkowski 3-forms, flux string vacua, axion stability and naturalness

A bstractWe discuss the role of Minkowski 3-forms in flux string vacua. In these vacua all internal closed string fluxes are in one to one correspondence with quantized Minkowski 4-forms. By performing a dimensional reduction of the D = 10 Type II supergravity actions we find that the 4-forms act as auxiliary fields of the Kahler and complex structure moduli in the effective action. We show that all the RR and NS axion dependence of the flux scalar potential appears through the said 4-forms. Gauge invariance of these forms then severely restricts the structure of the axion scalar potentials. Combined with duality symmetries it suggests that all perturbative corrections to the leading axion scalar potential V0 should appear as an expansion in powers of V0 itself. These facts could have an important effect e.g. on the inflaton models based on F-term axion monodromy. We also suggest that the involved multi-branched structure of string vacua provides for a new way to maintain interacting scalar masses stable against perturbative corrections.

BICEP2, the Higgs mass and the SUSY-breaking scale

Abstract Recent BICEP2 results on CMB polarisation B-modes suggest a high value for the inflation scale V 0 1 / 4 ≃ 10 16 GeV , giving experimental evidence for a physical scale in between the EW scale and the Planck mass. We propose that this new high scale could be interpreted as evidence for a high SUSY breaking scale with MSSM sparticles with masses of order M s s ≃ 10 12 – 10 13 GeV . We show that such a large value for M s s is consistent with a Higgs mass around 126 GeV. We briefly discuss some possible particle physics implications of this assumption.

The NMSSM with F-theory unified boundary conditions

A bstractWe study the phenomenological viability of a constrained NMSSM with parameters subject to unified boundary conditions from F-theory GUTs. We find that very simple assumptions about modulus dominance SUSY breaking in F-theory unification lead to a predictive set of boundary conditions, consistent with all phenomenological constraints. The second lightest scalar Higgs H2 can get a mass

The string origin of SUSY flavor violation

{m_{{{H_2}}}}\simeq 125

Flux-induced soft terms on type IIB/F-theory matter curves and hypercharge dependent scalar masses

GeV and has properties similar to the SM Higgs. On the other hand the lightest scalar H1, with a dominant singlet component, would have barely escaped detection at LEP and could be observable at LHC as a peak in H1 → γγ at around 100 GeV. The LSP is mostly singlino and is consistent with WMAP constraints due to coannihilation with the lightest stau, whose mass is in the range 100 − 250 GeV. Such light staus may lead to very characteristic signatures at LHC and be directly searched at linear colliders. In these models tan β is large, of order 50, still the branching ratio for Bs → μ+μ− is consistent with the LHCb bounds and in many cases is also even smaller than the SM prediction. Gluinos and squarks have masses in the 2−3 TeV region and may be accessible at the LHC at 14TeV. No large enhancement of the H2 → γγ rate over that of the SM Higgs is expected.