scholarly journals New Kähler invariant Fayet–Iliopoulos terms in supergravity and cosmological applications

2020 ◽  
Vol 80 (4) ◽  
Author(s):  
I. Antoniadis ◽  
F. Rondeau
Keyword(s):  
Vacuum Energy ◽  
Scalar Potential ◽  
Chiral Multiplet ◽  
Vector Multiplet ◽  
New Class ◽  
Gravitino Mass ◽  
New Models ◽  
Interesting Open Problem ◽  
New Type ◽  
Chiral Superfields

Abstract Recently, a new type of constant Fayet–Iliopoulos (FI) terms was introduced in $${\mathcal {N}}=1$$ N = 1 supergravity, which do not require the gauging of the R-symmetry. We revisit and generalise these constructions, building a new class of Kähler invariant FI terms parametrised by a function of the gravitino mass as functional of the chiral superfields, which is then used to describe new models of inflation. They are based on a no-scale supergravity model of the inflaton chiral multiplet, supplemented by an abelian vector multiplet with the new FI-term. We show that the inflaton potential is compatible with the CMB observational data, with a vacuum energy at the minimum that can be tuned to a tiny positive value. Finally, the axionic shift symmetry can be gauged by the U(1) which becomes massive. These models offer a mechanism for fixing the gravitino mass in no-scale supergravities, that corresponds to a flat direction of the scalar potential in the absence of the new FI-term; its origin in string theory is an interesting open problem.

Theoretical Studies of the Physical Properties of Rodlike and Related Polymers

1988 ◽  
Vol 134 ◽  
Author(s):  
W. J. Welsh ◽  
J. E. Mark ◽  
Y. Yang ◽  
G. P. Das
Keyword(s):  
High Performance ◽  
Liquid Crystalline ◽  
Theoretical Work ◽  
Environmental Resistance ◽  
New Class ◽  
Protonated Forms ◽  
New Type ◽  
Electrooptical Properties ◽  
Cis And Trans ◽  
Strong Acids

ABSTRACTThis review focuses on a new type of para-catenated aromatic polymer being used in the preparation of high-performance films and fibers of exceptional strength, thermal stability, and environmental resistance, including inertness to essentially all common solvents. Polymers of this type include the cis- and trans-poly(p-phenylene benzobisoxazole) (PBO), the cis- and trans-forms of the corresponding poly(pphenylene benzobisthiazole) (PBT), and the structurally similar poly(5,5ʹ-bibenzoxazole-2.2ʹ-diyl-l,3-phenylene) (AAPBO) and poly(2,5-benzoxazole) (ABPBO) and their sulfurcontaining analogues. Because of their rigidity, these polymers become highly oriented in solution and some display liquid crystalline behavior. The purpose of this paper is to summarize the authorsʹ theoretical work on the structures, conformational energies, intermolecular interactions, electronic properties, electrical conductivity, and electrooptical properties of these chains, including, in some cases, the so-called articulated forms and the protonated forms known to exist in strong acids. The emphasis is on how such studies provide a molecular understanding of the unusual properties and processing characteristics of this new class of materials.

A New Class of Oxide Superconductor (Nd, Ce, Sr)2CuO4

1989 ◽  
Vol 156 ◽  
Author(s):  
E. Takayama-Muromachi
Keyword(s):  
Crystal Structure ◽  
Crystal Chemistry ◽  
Superconducting Phase ◽  
Type Structure ◽  
Oxide Superconductor ◽  
New Class ◽  
System 2 ◽  
New Type ◽  
System 1 ◽  
Tetragonal Cell

ABSTRACTSince the discovery of the high-Tc superconductor in the La-Ba-Cu-O system [1], a great deal of experimental and theoretical effort have been made to clarify the nature of the Cu-based oxides. In order to elucidate mechanism of the high-Tc superconductivity, discovery of a new type of superconductor is no doubt of great importance. Recently, Akimitsu et al. found a new oxide superconductor in the Nd-Ce-Sr-Cu-O system [2]. Soon after their discovery, the superconducting phase was isolated and identified [3]. It has a tetragonal cell with space group P4/nmm and has a structure closely related to but different from the K2NiF4− or T'-Nd2CuO4− -type structure. Although, Tc of the Nd-Ce-Sr-Cu oxide is not so high (ca. 20 K) compared with the 1–2–3 or Bi(Tl)-based superconductors, it has aroused interest widely due to a very simple crystal structure. In this article, I will discuss superconductivity and crystal chemistry of the Nd-Ce-Sr-Cu oxide. Also, various compounds isostructural to it will be presented.

Allee’s Effect Bifurcation in Generalized Logistic Maps

2019 ◽  
Vol 29 (03) ◽  
pp. 1950039
Author(s):  
J. Leonel Rocha ◽  
Abdel-Kaddous Taha
Keyword(s):  
Allee Effect ◽  
Dynamical Behavior ◽  
Complete Classification ◽  
Unimodal Maps ◽  
New Class ◽  
New Type ◽  
Local And Global Bifurcations ◽  
One Dimensional Maps ◽  
Necessary And Sufficient

This paper concerns the study of the Allee effect on the dynamical behavior of a new class of generalized logistic maps. The fundamentals of the dynamics of this 4-parameter family of one-dimensional maps are presented. A complete classification of the nature and stability of its fixed points is provided. The main results relate to the Allee effect bifurcation: a new type of bifurcation introduced for this class of unimodal maps. A necessary and sufficient condition so that the Allee fixed point is a snap-back repeller is established. In addition, in the parameters space is defined an Allee’s effect region, which determines the existence of an essential extinction for the generalized logistic maps. Local and global bifurcations of generalized logistic maps are investigated.

scholarly journals Geometry of orientifold vacua and supersymmetry breaking

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Thibaut Coudarchet ◽  
Emilian Dudas ◽  
Hervé Partouche
Keyword(s):  
Field Theory ◽  
Supersymmetry Breaking ◽  
Effective Field Theory ◽  
Scalar Potential ◽  
Open String ◽  
Closed String ◽  
Effective Field ◽  
Internal Space ◽  
Gravitino Mass ◽  
The One

Abstract Starting from a peculiar orientifold projection proposed long ago by Angelantonj and Cardella, we elaborate on a novel perturbative scenario that involves only D-branes, together with the two types of orientifold planes O± and anti-orientifold planes $$ {\overline{\mathrm{O}}}_{\pm } $$ O ¯ ± . We elucidate the microscopic ingredients of such models, connecting them to a novel realization of brane supersymmetry breaking. Depending on the position of the D-branes in the internal space, supersymmetry can be broken at the string scale on branes, or alternatively only at the massive level. The main novelty of this construction is that it features no NS-NS disk tadpoles, while avoiding open-string instabilities. The one-loop potential, which depends on the positions of the D-branes, is minimized for maximally broken, non-linearly realized supersymmetry. The orientifold projection and the effective field theory description reveal a soft breaking of supersymmetry in the closed-string sector. In such models it is possible to decouple the gravitino mass from the value of the scalar potential, while avoiding brane instabilities.

A Novel, Low-Cost C-C Composite Heat Sink Material

1996 ◽  
Vol 445 ◽  
Author(s):  
W. Kowbel ◽  
V. Chellappa ◽  
J.C. Withers
Keyword(s):  
Thermal Conductivity ◽  
Heat Sink ◽  
Low Cost ◽  
Mechanical And Thermal Properties ◽  
New Class ◽  
Dielectric Coatings ◽  
Potential Applications ◽  
New Material ◽  
New Type ◽  
Composite Heat

AbstractRapid advances in high power electronics packaging require the development of new heat sink materials. Advanced composites designed to provide thermal expansion control as well as improved thermal conductivity have the potential to provide benefits in the removal of excess heat from electronic devices. Carbon-carbon (C-C) composits are under consideration for several military and space electronic applications including SEM-E electronic boxes. The high cost of C-C composits has greatly hindered their wide spread commercialization. A new manufacturing process has been developed to produce high thermal conductivity (over 400 W/mK) C-C composites at greatly reduced cost (less than $50/lb). This new material has potential applications as both a heat sink and a substrate. Dielectric coatings such as A1N and diamond were applied to this new type of heat sink material. Processing, as well as mechanical and thermal properties of this new class of heat sink material will be presented.

NEW PROPERTIES OF QUASIPERIODIC SOLUTIONS OF THE COMPLEX GINZBURG-LANDAU EQUATION

1992 ◽  
Vol 02 (04) ◽  
pp. 955-972 ◽  
Author(s):  
TATIANA S. AKHROMEYEVA ◽  
GEORGE G. MALINETSKII ◽  
ALEXEY B. POTAPOV ◽  
GEORGE Z. TSERTSVADZE
Keyword(s):  
Numerical Methods ◽  
Initial Data ◽  
Landau Equation ◽  
Mathematical Physics ◽  
Ginzburg Landau ◽  
New Class ◽  
A Value ◽  
Ginzburg Landau Equation ◽  
New Type ◽  
No Fluxes

By using analytical and numerical methods the authors study one of the basic models of mathematical physics—the so-called complex Ginzburg-Landau equation [Formula: see text] with the provision that no fluxes exist at the segment boundaries. A new class of solutions is found for this equation. It is shown that among its solutions there are analogs of limiting cycles of the second kind. A value describing these analogs is introduced, and a scenario of its variation depending on the parameters of the problem is given. A new type of spontaneous appearance of symmetry is shown when we go from initial data in the general form to spatially symmetrical solutions describing quasiperiodic regimes.

scholarly journals Testing swampland conjectures with machine learning

2020 ◽  
Vol 80 (8) ◽  
Author(s):  
Nana Cabo Bizet ◽  
Cesar Damian ◽  
Oscar Loaiza-Brito ◽  
Damián Kaloni Mayorga Peña ◽  
J. A. Montañez-Barrera
Keyword(s):  
Neural Network ◽  
Machine Learning ◽  
Vacuum Energy ◽  
Matrix Theory ◽  
Scalar Potential ◽  
Supervised Machine Learning ◽  
Machine Learning Techniques ◽  
De Sitter ◽  
Learning Techniques ◽  
Isotropic Torus

Abstract We consider Type IIB compactifications on an isotropic torus $$T^6$$T6 threaded by geometric and non geometric fluxes. For this particular setup we apply supervised machine learning techniques, namely an artificial neural network coupled to a genetic algorithm, in order to obtain more than sixty thousand flux configurations yielding to a scalar potential with at least one critical point. We observe that both stable AdS vacua with large moduli masses and small vacuum energy as well as unstable dS vacua with small tachyonic mass and large energy are absent, in accordance to the refined de Sitter conjecture. Moreover, by considering a hierarchy among fluxes, we observe that perturbative solutions with small values for the vacuum energy and moduli masses are favored, as well as scenarios in which the lightest modulus mass is much smaller than the corresponding AdS vacuum scale. Finally we apply some results on random matrix theory to conclude that the most probable mass spectrum derived from this string setup is that satisfying the Refined de Sitter and AdS scale conjectures.

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 Low energy supergravity revisited (I)

2019 ◽  
Vol 34 (01) ◽  
pp. 1950004
Author(s):  
Gilbert Moultaka ◽  
Michel Rausch de Traubenberg ◽  
Damien Tant
Keyword(s):  
Model Building ◽  
Vacuum Expectation ◽  
Complete Classification ◽  
Low Energy ◽  
Rigorous Approach ◽  
Hidden Sector ◽  
New Type ◽  
The One ◽  
The Masses ◽  
Chiral Superfields

General forms of the Kähler and superpotenials that lead to consistent low energy broken Supersymmetry originating from N[Formula: see text]=[Formula: see text]1 Supergravity have been classified and used for model building since more than three decades. We point out the incompleteness of this classification when hidden sector vacuum expectation values are of the order of the Planck mass. Focusing in this paper mainly on the case of minimal Kähler potential, we adopt a rigorous approach that retrieves on the one hand the known forms, and demonstrate on the other hand the existence of a whole set of new forms for the superpotential of which we give a complete classification. The latter forms involve a new type of chiral superfields having the unusual property of belonging neither to the hidden sector nor to the conventional observable sector. Comparing the obtained forms with the conventional ones, we argue how new possibilities for model building can arise, and discuss the gravity mediation of soft as well as additional hard (but parametrically small) Supersymmetry breaking, in the presence of the new type of chiral superfields. In the simplest case, we study the vacuum structure, characterize the masses and couplings of the scalar components to the hidden and observable sectors and discuss briefly the physical role they could play. In the generic case, we estimate the magnitude and possible consequences of the hard breaking of Supersymmetry in terms of the interplay between hidden and visible sector mass scales.

A new type of composite MOFs based on high-valent Sb(v)-based units and cuprous-halide clusters

2019 ◽  
Vol 55 (100) ◽  
pp. 15113-15116 ◽  
Author(s):  
Li-Dan Lin ◽  
Zhong Li ◽  
Jin-Hua Liu ◽  
Yan-Qiong Sun ◽  
Xin-Xiong Li ◽  
...  
Keyword(s):  
New Class ◽  
New Type ◽  
High Valent ◽  
First Time

In this work, an unusual high-valent Sb(v)-based [SbL2]− unit was developed for the first time to combine with various cuprous-halide clusters for the construction of a brand-new class of heterometallic MOFs.

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