scholarly journals On the Superstrings-Induced Four-Dimensional Gravity and Its Applications to Cosmology

2008 ◽  
Vol 2008 ◽  
pp. 1-27 ◽  
Author(s):  
Masao Iihoshi ◽  
Sergei V. Ketov
Keyword(s):  
Effective Action ◽  
Leading Order ◽  
De Sitter ◽  
Frw Cosmology ◽  
Spacetime Singularity ◽  
Spacetime Curvature ◽  
The Status ◽  
Dimensional Gravity ◽  
Definition Of ◽  
M Theory

We review the status of the fourth-order (quartic in the spacetime curvature) terms induced by superstrings/M-theory (compactified on a warped torus) in the leading order with respect to the Regge slope parameter, and study their (nonperturbative) impact on the evolution of the Hubble scale in the context of the four-dimensional FRW cosmology. After taking into account the quantum ambiguities in the definition of the off-shell superstring effective action, we propose the generalized Friedmann equations, find the existence of their (de Sitter) exact inflationary solutions without a spacetime singularity, and constrain the ambiguities by demanding stability and the scale factor duality invariance of our solutions. The most naive (Bel-Robinson tensor squared) quartic terms are ruled out, thus giving the evidence for the necessity of extra quartic (Ricci tensor-dependent) terms in the off-shell gravitational effective action for superstrings. Our methods are generalizable to the higher orders in the spacetime curvature.

scholarly journals ON THE QUARTIC CURVATURE GRAVITY IN THE CONTEXT OF FRW COSMOLOGY

2008 ◽  
Vol 23 (14n15) ◽  
pp. 2153-2160 ◽  
Author(s):  
MASAO IIHOSHI ◽  
SERGEI V. KETOV
Keyword(s):  
Fourth Order ◽  
Quantum Corrections ◽  
Slope Parameter ◽  
Leading Order ◽  
Frw Cosmology ◽  
Friedmann Equations ◽  
Spacetime Singularity ◽  
Spacetime Curvature ◽  
Rule Out

We consider the purely gravitational fourth-order (in the spacetime curvature) quantum corrections to the Einstein-Hilbert gravity action, coming from superstrings in the leading order with respect to the Regge slope parameter, and study their impact on the evolution of the Hubble scale in the context of the FRW cosmology, in four spacetime dimensions. We propose the generalized Friedmann equations, and rule out the most naive (Bel-Robinson tensor squared) gravity. Our new cosmological equations have exact inflationary solutions without a spacetime singularity.

scholarly journals Forward Higgs production within high energy factorization in the heavy quark limit at next-to-leading order accuracy

2021 ◽  
Vol 81 (2) ◽  
Author(s):  
M. Hentschinski ◽  
K. Kutak ◽  
A. van Hameren
Keyword(s):  
Effective Action ◽  
High Energy ◽  
Higgs Production ◽  
Explicit Calculation ◽  
Leading Order ◽  
Forward Region ◽  
Transverse Momentum Dependent ◽  
Heavy Quark Limit ◽  
Proper Definition ◽  
Definition Of

AbstractWe use Lipatov’s high energy effective action to determine the next-to-leading order corrections to Higgs production in the forward region within high energy factorization making use of the infinite top mass limit. Our result is based on an explicit calculation of real corrections combined with virtual corrections determined earlier by Nefedov. As a new element we provide a proper definition of the desired next-to-leading order coefficient within the high energy effective action framework, extending a previously proposed prescription. We further propose a subtraction mechanism to achieve for this coefficient a stable cancellation of real and virtual infra-red singularities in the presence of external off-shell legs. Apart from its relevance for direct phenomenological studies, such as high energy resummation of Higgs $$+$$ + jet configurations, our result will be further of use for the study of transverse momentum dependent factorization in the high energy limit.

Slave Women and Their Descendants among the Upper Classes in Tetouan, Morocco (1859–1956): Between Recognition and Conflict

2020 ◽  
pp. 036319902096739
Author(s):  
Josep Lluís Mateo Dieste
Keyword(s):  
Skin Color ◽  
Arab World ◽  
Family Members ◽  
Negative Stereotypes ◽  
The Social ◽  
Form Part ◽  
Slave Women ◽  
The Status ◽  
Definition Of ◽  
Determinant Factor

In the Arab world, the recognized children of elite men and slave women could adopt the status of their father, ignoring the slave origin of the mother, owing to a system of patrilineal transmission. This regime co-existed with negative stereotypes toward slaves and blackness, despite the very fact that—as this study of notable families in Tetouan between 1859 and 1956 demonstrates—skin color was not the determinant factor to form part of this group. Rather, it was based on the social definition of filiation, leading to legal disputes between family members to delineate the boundaries of kinship.

scholarly journals Rethinking Southern Europe: Society, Networks and Politics

2021 ◽  
pp. 1-10
Author(s):  
Alan Granadino ◽  
Eirini Karamouzi ◽  
Rinna Kullaa
Keyword(s):  
Cold War ◽  
Southern Europe ◽  
Eurozone Crisis ◽  
Development Education ◽  
Family Structures ◽  
Conceptual Clarity ◽  
Welfare Systems ◽  
The Status ◽  
Nineteenth And Twentieth Centuries ◽  
Definition Of

Writing and researching Southern Europe as a symbiotic area has always presented a challenging task. Historians and political scientists such as Stanley Payne, Edward Malefakis, Giulio Sapelli, and Roberto Aliboni have studied the concept of Southern Europe and its difficult paths to modernity. They have been joined by sociologists and anthropologists who have debated the existence of a Southern European paradigm in the nineteenth and twentieth centuries and the arduous transformation of the region's welfare systems, economic development, education and family structures. These scholarly attempts to understand the specificities of Southern Europe date back to the concerns of Western European Cold War strategists in the 1970s, many of whom were worried about the status quo of the region in the aftermath of the fall of the dictatorships. But this geographical and geopolitical definition of the area did not necessarily follow existing cultural, political and economic patterns. Once the Eurozone crisis hit in the 2000s these questions came back with renewed force but with even less conceptual clarity, as journalists and pundits frequently gestured towards vague notions of what they considered to be ‘Southern Europe’.

scholarly journals Solving puzzles in deformed JT gravity: phase transitions and non-perturbative effects

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Clifford V. Johnson ◽  
Felipe Rosso
Keyword(s):  
Phase Structure ◽  
Scalar Potential ◽  
String Equation ◽  
Two Dimensional ◽  
Leading Order ◽  
Classical Analysis ◽  
First Order ◽  
First Order Phase Transition ◽  
Definition Of ◽  
First Order Phase

Abstract Recent work has shown that certain deformations of the scalar potential in Jackiw-Teitelboim gravity can be written as double-scaled matrix models. However, some of the deformations exhibit an apparent breakdown of unitarity in the form of a negative spectral density at disc order. We show here that the source of the problem is the presence of a multi-valued solution of the leading order matrix model string equation. While for a class of deformations we fix the problem by identifying a first order phase transition, for others we show that the theory is both perturbatively and non-perturbatively inconsistent. Aspects of the phase structure of the deformations are mapped out, using methods known to supply a non-perturbative definition of undeformed JT gravity. Some features are in qualitative agreement with a semi-classical analysis of the phase structure of two-dimensional black holes in these deformed theories.

Grammatik der Narration

2020 ◽  
Vol 48 (3) ◽  
pp. 457-494
Author(s):  
Sonja Zeman
Keyword(s):  
Narrative Discourse ◽  
Linguistic Theory ◽  
Second Step ◽  
Narrative Fiction ◽  
The Status ◽  
Definition Of ◽  
Narrative Syntax

AbstractIs there a ‚narrative syntax‘, i. e. a special grammar restricted to narrative fiction? Starting from this question which has been investigated since early structuralism, the paper focusses on grammatical characteristics of narrative discourse mode and their implications for a linguistic theory of narration. Its goal is two-fold: In a first step, the traditional accounts by Benveniste, Hamburger, Kuroda and recent typological studies are brought together in order to support the claim that the distinction between narrative and non-narrative discourse mode is a fundamental one that has consequences for the use of grammar. In a second step, I discuss three central questions within the intersection between narrative micro- and macro-structures, namely (i) the definition of narrativity, (ii) the status of the narrator, and (iii) the relation between narration and fictionality. In sum, the article argues that investigations on the ‘grammar of narration’ do not just offer insights into a specific text configuration next to others, but are deeply linked to fundamental theoretical questions concerning the architecture of language – and that the comparison between linguistic and narratological categories offers a potential for addressing them.

scholarly journals Geometries with mismatched branes

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Andreas Karch ◽  
Lisa Randall
Keyword(s):  
Boundary Conditions ◽  
Effective Action ◽  
Cosmological Models ◽  
Time Dependent ◽  
De Sitter ◽  
Stabilization Mechanism ◽  
New Class ◽  
Vacuum Solutions ◽  
Single Coordinate

Abstract We study Randall-Sundrum two brane setups with mismatched brane tensions. For the vacuum solutions, boundary conditions demand that the induced metric on each of the branes is either de Sitter, Anti-de Sitter, or Minkowski. For incompatible boundary conditions, the bulk metric is necessarily time-dependent. This introduces a new class of time-dependent solutions with the potential to address cosmological issues and provide alternatives to conventional inflationary (or contracting) scenarios. We take a first step in this paper toward such solutions. One important finding is that the resulting solutions can be very succinctly described in terms of an effective action involving only the induced metric on either one of the branes and the radion field. But the full geometry cannot necessarily be simply described with a single coordinate patch. We concentrate here on the time- dependent solutions but argue that supplemented with a brane stabilization mechanism one can potentially construct interesting cosmological models this way. This is true both with and without a brane stabilization mechanism.

scholarly journals Effective Action from M-Theory on Twisted Connected Sum G 2-Manifolds

2017 ◽  
Vol 359 (2) ◽  
pp. 535-601 ◽  
Author(s):  
Thaisa C. da C. Guio ◽  
Hans Jockers ◽  
Albrecht Klemm ◽  
Hung-Yu Yeh
Keyword(s):  
Effective Action ◽  
Connected Sum ◽  
M Theory

The Humdrum Use of Ultimate Authority: Defining and Analysing Chapter VII Resolutions

2009 ◽  
Vol 78 (3) ◽  
pp. 309-342 ◽  
Author(s):  
Patrik Johansson
Keyword(s):  
Cold War ◽  
United Nations ◽  
Security Council ◽  
Security Council Resolution ◽  
Post Cold War ◽  
Standard Definition ◽  
The Status ◽  
Definition Of ◽  
The Cold War ◽  
Business As Usual

AbstractUnder Chapter VII of the Charter of the United Nations, the Security Council has the unique authority to make decisions that are binding on member states. However, the lack of a standard definition of what makes a Security Council resolution "a Chapter VII resolution" has caused disagreement regarding the status of several resolutions. This is unfortunate as the international community should never have to doubt whether a Security Council resolution is in fact adopted under Chapter VII or not. It is also unnecessary. This article addresses this problem by proposing a definition of Chapter VII resolutions, based on two criteria referred to as "Article 39 determinations" and "Chapter VII decisions". On the basis of the proposed definition, the article describes and analyses a dramatic increase in the use of Chapter VII during the post-Cold War era. It concludes that as Chapter VII has come to constitute the majority of Security Council resolutions in recent years, the resort to Chapter VII no longer signifies exceptional determination and resolve, which it did during the Cold War; instead Chapter VII today implies business as usual. An appendix lists all Chapter VII resolutions from 1946–2008.

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