scholarly journals STRING NO-SCALE SUPERGRAVITY

1996 ◽  
Vol 11 (19) ◽  
pp. 3439-3477 ◽  
Author(s):  
JORGE L. LOPEZ ◽  
D.V. NANOPOULOS
Keyword(s):  
Supersymmetry Breaking ◽  
Vacuum Energy ◽  
Scalar Potential ◽  
Gauge Coupling ◽  
Supersymmetric Particle ◽  
Scale Models ◽  
Fermionic String ◽  
Soft Supersymmetry Breaking ◽  
The Stability ◽  
String Models

We explore the postulates of string no-scale supergravity in the context of free-fermionic string models. The requirements of vanishing vacuum energy, flat directions of the scalar potential, and stable no-scale mechanism impose strong restrictions on possible string no-scale models, which must possess only two or three moduli, and a constrained massless spectrum. The soft-supersymmetry-breaking parameters involving all twisted and untwisted fields are given explicitly. Our calculations take into account the possible existence of an anomalous U A(1) factor in the gauge group, and reveal some novel effects concerning the stability of the no-scale mechanism in the presence of U A(1). This class of models contains no free parameters, i.e. in principle all supersymmetric particle masses and interactions are completely determined. A computerized search for free-fermionic models with the desired properties yields a candidate SU (5)×U(1) model containing extra [Formula: see text] matter representations that allow gauge coupling unification at the string scale. Our candidate model possesses a benign nonuniversal assignment of supersymmetry-breaking scalar masses, which may have interesting low-energy experimental consequences.

scholarly journals Local string models of soft supersymmetry breaking

2004 ◽  
Vol 2004 (06) ◽  
pp. 007-007 ◽  
Author(s):  
Albion Lawrence ◽  
John McGreevy
Keyword(s):  
Supersymmetry Breaking ◽  
Soft Supersymmetry Breaking ◽  
String Models

scholarly journals Scale hierarchies in particle physics and cosmology

2018 ◽  
Vol 182 ◽  
pp. 02005
Author(s):  
I. Antoniadis
Keyword(s):  
Cosmological Constant ◽  
Supersymmetry Breaking ◽  
Particle Physics ◽  
Scalar Potential ◽  
Low Energy ◽  
Chiral Multiplet ◽  
Positive Cosmological Constant ◽  
Shift Symmetry ◽  
Kähler Potential ◽  
Soft Supersymmetry Breaking

I describe the phenomenology of a model of supersymmetry breaking in the presence of a tiny (tuneable) positive cosmological constant. It utilises a single chiral multiplet with a gauged shift symmetry, that can be identified with the string dilaton (or an appropriate compactification modulus). The model is coupled to the MSSM, leading to calculable soft supersymmetry breaking masses and a distinct low energy phenomenology that allows to differentiate it from other models of supersymmetry breaking and mediation mechanisms. We also study the question if this model can lead to inflation by identifying the dilaton with the inflaton. We find that this is possible if the Kähler potential is modified by a term that has the form of NS5-brane instantons, leading to an appropriate inflationary plateau around the maximum of the scalar potential, depending on two extra parameters.

scholarly journals VANISHING OF THE COSMOLOGICAL CONSTANT, STABILITY OF THE DILATON AND INFLATION

1996 ◽  
Vol 05 (05) ◽  
pp. 567-578
Author(s):  
A. DE LA MACORRA
Keyword(s):  
Cosmological Constant ◽  
Vacuum Energy ◽  
Scalar Potential ◽  
Suitable Choice ◽  
Dilaton Field ◽  
String Models ◽  
Large Hierarchy ◽  
Chiral Potential

We study the possibility of canceling the cosmological constant in supergravity string models. We show that with a suitable choice of superpotential the vacuum energy may vanish with the dilaton field at its minimum and supersymmetry broken with a large hierarchy. We derive the condition for which the introduction of a chiral potential, e.g. the inflaton potential, does not destabilize the dilaton field even in the region where the scalar potential takes positive values. This allows for an inflationary potential with the dilaton frozen at its minimum.

scholarly journals Inflation from Supersymmetry Breaking

Universe ◽  
2019 ◽  
Vol 5 (1) ◽  
pp. 30 ◽  
Author(s):  
Ignatios Antoniadis
Keyword(s):  
Supersymmetry Breaking ◽  
Vacuum Energy ◽  
Scalar Potential ◽  
Small Field ◽  
Slow Roll ◽  
Cosmological Observations ◽  
Interesting Class ◽  
The Universe ◽  
R Symmetry

I discuss the possibility that inflation is driven by supersymmetry breaking, with the superpartner of the goldstino (sgoldstino) playing the role of the inflaton. Imposing an R-symmetry to satisfy the slow-roll conditions, avoiding the so-called η -problem, leads to an interesting class of small field inflation models, characterised by an inflationary plateau around the maximum of scalar potential near the origin, where R-symmetry is restored with the inflaton rolling down to a minimum, describing the present phase of the Universe. Inflation can be driven by either an F- or a D-term, while the minimum has a positive tuneable vacuum energy. The models agree with cosmological observations and, in the simplest case, predict a rather small tensor-to-scalar ratio of primordial perturbations. This talk is an extended version of an earlier review (Antoniadis, 2018).

scholarly journals Gauge coupling unification due to non-universal soft supersymmetry breaking

1994 ◽  
Vol 329 (1) ◽  
pp. 27-32 ◽  
Author(s):  
Tatsuo Kobayashi ◽  
Daijiro Suematsu ◽  
Yoshio Yamagishi
Keyword(s):  
Supersymmetry Breaking ◽  
Gauge Coupling ◽  
Soft Supersymmetry Breaking

scholarly journals Gauge coupling unification in realistic free-fermionic string models

1995 ◽  
Vol 457 (3) ◽  
pp. 409-483 ◽  
Author(s):  
Keith R. Dienes ◽  
Alon E. Faraggi
Keyword(s):  
Gauge Coupling ◽  
Fermionic String ◽  
String Models

Challenges in string and supersymmetric cosmology

2021 ◽  
pp. 2044030
Author(s):  
Ignatios Antoniadis ◽  
Auttakit Chatrabhuti
Keyword(s):  
Supersymmetry Breaking ◽  
Vacuum Energy ◽  
Scalar Potential ◽  
Small Field ◽  
Slow Roll ◽  
Cosmological Observations ◽  
Interesting Class ◽  
The Universe ◽  
R Symmetry

We discuss the possibility that inflation is driven by supersymmetry breaking with the superpartner of the goldstino (sgoldstino) playing the role of the inflaton. Imposing an R-symmetry allows to satisfy easily the slow-roll conditions, avoiding the so-called [Formula: see text]-problem, and leads to an interesting class of small field inflation models, characterized by an inflationary plateau around the maximum of the scalar potential near the origin, where R-symmetry is restored with the inflaton rolling down to a minimum describing the present phase of the Universe. Inflation can be driven by either an [Formula: see text]- or a [Formula: see text]-term, while the minimum has a positive tuneable vacuum energy. The models agree with cosmological observations and in the simplest case predict a rather small tensor-to-scalar ratio of primordial perturbations.

scholarly journals Scale hierarchies, supersymmetry and cosmology

2018 ◽  
Vol 33 (34) ◽  
pp. 1845003
Author(s):  
Ignatios Antoniadis
Keyword(s):  
Supersymmetry Breaking ◽  
General Class ◽  
Vacuum Energy ◽  
Scalar Potential ◽  
Small Field ◽  
Slow Roll ◽  
Cosmological Observations ◽  
R Symmetry

I discuss a general class of models where the inflation is driven by supersymmetry breaking with the superpartner of the goldstino (sgoldstino) playing the role of the inflaton. Imposing an R-symmetry allows to satisfy easily the slow-roll conditions, avoiding the so-called [Formula: see text]-problem, and leads to two different classes of small field inflation models; they are characterized by an inflationary plateau around the maximum of the scalar potential, where R-symmetry is either restored or spontaneously broken, with the inflaton rolling down to a minimum describing the present phase of our universe. Inflation can be driven by either an F- or a D-term, while the minimum has a positive tuneable vacuum energy. The models agree with cosmological observations and in the simplest case predict a tensor-to-scalar ratio of primordial perturbations [Formula: see text] and an inflation scale [Formula: see text].

Scale hierarchies and string cosmology

2017 ◽  
Vol 32 (17) ◽  
pp. 1730012
Author(s):  
I. Antoniadis
Keyword(s):  
Cosmological Constant ◽  
Supersymmetry Breaking ◽  
Scalar Potential ◽  
String Cosmology ◽  
Low Energy ◽  
Chiral Multiplet ◽  
Positive Cosmological Constant ◽  
Shift Symmetry ◽  
Kähler Potential ◽  
Soft Supersymmetry Breaking

I describe the phenomenology of a model of supersymmetry breaking in the presence of a tiny (tuneable) positive cosmological constant. It utilizes a single chiral multiplet with a gauged shift symmetry, that can be identified with the string dilaton (or an appropriate compactification modulus). The model is coupled to the MSSM, leading to calculable soft supersymmetry breaking masses and a distinct low energy phenomenology that allows to differentiate it from other models of supersymmetry breaking and mediation mechanisms. We also study the question if this model can lead to inflation by identifying the dilaton with the inflaton. We find that this is possible if the Kähler potential is modified by a term that has the form of NS5-brane instantons, leading to an appropriate inflationary plateau around the maximum of the scalar potential, depending on two extra parameters.

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