scholarly journals The axion quality problem: global symmetry breaking and wormholes

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
James Alvey ◽  
Miguel Escudero
Keyword(s):  
String Theory ◽  
Symmetry Breaking ◽  
Global Symmetries ◽  
Open String ◽  
Einstein Gravity ◽  
Current Status ◽  
Global Symmetry ◽  
Quality Problem ◽  
Global Symmetry Group ◽  
The Impact

Abstract Continuous global symmetries are expected to be broken by gravity, which can lead to important phenomenological consequences. A prime example is the threat that this poses to the viability of the Peccei-Quinn solution to the strong CP problem. In this paper, we explore the impact of wormholes as a source of global symmetry breaking by gravity. We review the current status of wormholes and global symmetries and note that, surprisingly, the axion has a quality problem within non-perturbative Einstein gravity. Although these wormholes lead to a large breaking of global symmetries, we show that their effect is nonetheless relevant for the model building of gauge protected axions. We also find wormhole solutions within two scenarios: (i) an extended global symmetry group within Einstein gravity, and (ii) U(1) wormholes within the low-energy limit of an open String Theory. The former allows us to show that the concept of a global symmetry in General Relativity is somewhat ill-defined. The latter illustrates that for motivated values of the string coupling constant, axions appear to have a quality problem within the open String Theory we consider.

Quantum chromodynamics

2018 ◽  
Author(s):  
Marcos Marino
Keyword(s):  
Symmetry Breaking ◽  
Dirac Operator ◽  
Global Symmetries ◽  
Quantum Chromodynamics ◽  
Random Matrix Theory ◽  
Random Matrix ◽  
Degrees Of Freedom ◽  
Chemical Potential ◽  
Matrix Theory ◽  
Global Symmetry

This article focuses on chiral random matrix theories with the global symmetries of quantum chromodynamics (QCD). In particular, it explains how random matrix theory (RMT) can be applied to the spectra of the Dirac operator both at zero chemical potential, when the Dirac operator is Hermitian, and at non-zero chemical potential, when the Dirac operator is non-Hermitian. Before discussing the spectra of these Dirac operators at non-zero chemical potential, the article considers spontaneous symmetry breaking in RMT and the QCD partition function. It then examines the global symmetries of QCD, taking into account the Dirac operator for a finite chiral basis, as well as the global symmetry breaking pattern and the Goldstone manifold in chiral random matrix theory (chRMT). It also describes the generating function for the Dirac spectrum and applications of chRMT to QCD to gauge degrees of freedom.

scholarly journals WILSON LOOPS IN OPEN STRING THEORY

1988 ◽  
Vol 03 (03) ◽  
pp. 283-287 ◽  
Author(s):  
KIYOSHI SHIRAISHI
Keyword(s):  
String Theory ◽  
Partition Function ◽  
Symmetry Breaking ◽  
Path Integral ◽  
Wilson Loop ◽  
Mass Spectra ◽  
Open String ◽  
Wilson Loops ◽  
Open Strings ◽  
Correct Weight

Wilson loop elements on torus are introduced into the partition function of open strings as Polyakov’s path integral at one-loop level. Mass spectra from compactification and expected symmetry breaking are illustrated by choosing the correct weight for the contributions from annulus and Möbius strip. We show that Jacobi’s imaginary transformation connects the mass spectra with the Wilson loops. The application to thermopartition function and cosmological implications are briefly discussed.

scholarly journals Chern-Weil global symmetries and how quantum gravity avoids them

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
Ben Heidenreich ◽  
Jacob McNamara ◽  
Miguel Montero ◽  
Matthew Reece ◽  
Tom Rudelius ◽  
...  
Keyword(s):  
Field Theory ◽  
String Theory ◽  
Quantum Gravity ◽  
Global Symmetries ◽  
Effective Field Theory ◽  
Degrees Of Freedom ◽  
Effective Field ◽  
Global Symmetry ◽  
Unified Framework ◽  
Particle Phenomenology

Abstract We draw attention to a class of generalized global symmetries, which we call “Chern-Weil global symmetries,” that arise ubiquitously in gauge theories. The Noether currents of these Chern-Weil global symmetries are given by wedge products of gauge field strengths, such as F2 ∧ H3 and tr($$ {F}_2^2 $$ F 2 2 ), and their conservation follows from Bianchi identities. As a result, they are not easy to break. However, it is widely believed that exact global symmetries are not allowed in a consistent theory of quantum gravity. As a result, any Chern-Weil global symmetry in a low-energy effective field theory must be either broken or gauged when the theory is coupled to gravity. In this paper, we explore the processes by which Chern-Weil symmetries may be broken or gauged in effective field theory and string theory. We will see that many familiar phenomena in string theory, such as axions, Chern-Simons terms, worldvolume degrees of freedom, and branes ending on or dissolving in other branes, can be interpreted as consequences of the absence of Chern-Weil symmetries in quantum gravity, suggesting that they might be general features of quantum gravity. We further discuss implications of breaking and gauging Chern-Weil symmetries for particle phenomenology and for boundary CFTs of AdS bulk theories. Chern-Weil global symmetries thus offer a unified framework for understanding many familiar aspects of quantum field theory and quantum gravity.

Clinical Pharmacokinetic Studies in Pregnant Women and the Relevance of Pharmacometric Tools

2019 ◽  
Vol 25 (5) ◽  
pp. 483-495 ◽  
Author(s):  
André Dallmann ◽  
Paola Mian ◽  
Johannes Van den Anker ◽  
Karel Allegaert
Keyword(s):  
Pregnant Women ◽  
Clinical Pharmacokinetic ◽  
Individual Variability ◽  
Current Status ◽  
Pharmacokinetic Studies ◽  
Full Potential ◽  
Pbpk Models ◽  
Pregnancy And Postpartum ◽  
Population Pk ◽  
The Impact

Background: In clinical pharmacokinetic (PK) studies, pregnant women are significantly underrepresented because of ethical and legal reasons which lead to a paucity of information on potential PK changes in this population. As a consequence, pharmacometric tools became instrumental to explore and quantify the impact of PK changes during pregnancy. Methods: We explore and discuss the typical characteristics of population PK and physiologically based pharmacokinetic (PBPK) models with a specific focus on pregnancy and postpartum. Results: Population PK models enable the analysis of dense, sparse or unbalanced data to explore covariates in order to (partly) explain inter-individual variability (including pregnancy) and to individualize dosing. For population PK models, we subsequently used an illustrative approach with ketorolac data to highlight the relevance of enantiomer specific modeling for racemic drugs during pregnancy, while data on antibiotic prophylaxis (cefazolin) during surgery illustrate the specific characteristics of the fetal compartments in the presence of timeconcentration profiles. For PBPK models, an overview on the current status of reports and papers during pregnancy is followed by a PBPK cefuroxime model to illustrate the added benefit of PBPK in evaluating dosing regimens in pregnant women. Conclusions: Pharmacometric tools became very instrumental to improve perinatal pharmacology. However, to reach their full potential, multidisciplinary collaboration and structured efforts are needed to generate more information from already available datasets, to share data and models, and to stimulate cross talk between clinicians and pharmacometricians to generate specific observations (pathophysiology during pregnancy, breastfeeding) needed to further develop the field.

Perspectives on the Situation

2018 ◽  
pp. 66-96
Author(s):  
Harry T. Reis ◽  
John G. Holmes
Keyword(s):  
Personality Traits ◽  
Current Status ◽  
Psychological Processes ◽  
Social Psychological ◽  
The Impact

This chapter reviews major theoretical positions on the influence of situations for the understanding of both personality and social–psychological processes. We review the history and current status of this topic, and we describe in some detail two recent theories that seem particularly amenable toward resolving the disparate approaches that this distinction often engenders. Broadly considered, our position is that personality and situations must be considered interacting factors, but in a theoretically specific way. The concept of affordance—that situations provide opportunities for the expression of certain personality traits—is central to our analysis. We also discuss several issues that personality and social psychologists might profitably consider to provide better grounding for theories and research about the impact of situations on behavior.

Tourism research for the GCC region: Current status and future research directions

2021 ◽  
pp. 135481662199996
Author(s):  
Ali Salman Saleh ◽  
Charbel Bassil ◽  
Arsalan Safari
Keyword(s):  
United Arab Emirates ◽  
Current Status ◽  
Future Research ◽  
Research Directions ◽  
Regional Tourism ◽  
Research Theme ◽  
Tourism Sector ◽  
Future Research Directions ◽  
Meta Analyses ◽  
The Impact

Tourism in the Gulf Cooperation Council (GCC) countries has recently been considered by policymakers as a new avenue for economic diversification. Despite the considerable literature concerning the impact of tourism worldwide, only a limited number of studies have looked at the tourism sector in the GCC region or analyzed its economic, sociocultural, and environmental impacts. This article therefore conducts a systematic review of the state of the literature related to tourism in the GCC region. It provides effective insights about the current status, gaps, and challenges and proposes future research directions in this area for academics, practitioners, and policymakers with an interest in regional tourism development. The preferred reporting items for systematic reviews and meta-analyses approach was used to identify and select the papers. Some 23 papers were identified and analyzed. The majority of these studies focused on the United Arab Emirates, specifically the Dubai emirate. We found the most dominant research theme to be tourism planning.

scholarly journals Viability Assessment in Liver Transplantation—What Is the Impact of Dynamic Organ Preservation?

Biomedicines ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 161
Author(s):  
Rebecca Panconesi ◽  
Mauricio Flores Carvalho ◽  
Matteo Mueller ◽  
David Meierhofer ◽  
Philipp Dutkowski ◽  
...  
Keyword(s):  
Liver Function ◽  
Organ Preservation ◽  
Ex Situ ◽  
Current Status ◽  
Intensive Care Treatment ◽  
Viability Assessment ◽  
Great Opportunity ◽  
Continuous Increase ◽  
Diagnostic Time ◽  
The Impact

Based on the continuous increase of donor risk, with a majority of organs classified as marginal, quality assessment and prediction of liver function is of utmost importance. This is also caused by the notoriously lack of effective replacement of a failing liver by a device or intensive care treatment. While various parameters of liver function and injury are well-known from clinical practice, the majority of specific tests require prolonged diagnostic time and are more difficult to assess ex situ. In addition, viability assessment of procured organs needs time, because the development of the full picture of cellular injury and the initiation of repair processes depends on metabolic active tissue and reoxygenation with full blood over several hours or days. Measuring injury during cold storage preservation is therefore unlikely to predict the viability after transplantation. In contrast, dynamic organ preservation strategies offer a great opportunity to assess organs before implantation through analysis of recirculating perfusates, bile and perfused liver tissue. Accordingly, several parameters targeting hepatocyte or cholangiocyte function or metabolism have been recently suggested as potential viability tests before organ transplantation. We summarize here a current status of respective machine perfusion tests, and report their clinical relevance.

67 Current Status and Future Prospective of the Use of Plant Bioactive Compounds in Dairy and Beef Cattle

2021 ◽  
Vol 99 (Supplement_1) ◽  
pp. 132-132
Author(s):  
Sergio Calsamiglia ◽  
Maria Rodriguez-Prado ◽  
Gonzalo Fernandez-Turren ◽  
Lorena Castillejos
Keyword(s):  
Beef Cattle ◽  
Essential Oils ◽  
Average Daily Gain ◽  
Rumen Fermentation ◽  
Production Performance ◽  
In Vivo Studies ◽  
Current Status ◽  
The Impact

Abstract In the last 20 years there has been extensive in vitro research on the effects of plant extracts and essential oils on rumen microbial fermentation. The main objectives have been to improve energy metabolism through a reduction in methane emissions and an increase in propionate production; and to improve protein metabolism by reducing proteolysis and deamination. While the positive results from in vitro studies has stimulated the release of commercial products based on blends of essential oils, there is limited in vivo evidence on the rumen fermentation and production performance effects. A literature search was conducted to select in vivo studies where information on rumen fermentation and animal performance was reported. For dairy cattle, we identified 37 studies of which 21 were adequate to test production performance. Ten studies reported increases and 3 decreases in milk yield. For beef cattle, we identified 20 studies with rumen fermentation profile and 22 with performance data. Average daily gain improved in 7 and decreased in 1 study. Only 1 out of 16 studies reported an improvement in feed efficiency. Data indicate that out of more than 500 products tested in vitro, only around 20 have been tested in vivo in different mixtures and doses. The use of statistical approaches will allow to describe the conditions, doses and responses in dairy and beef cattle performance. The search for postruminal effects offers another alternative use. Evidence for effects on the intestinal and systemic effects on the immune system and antioxidant status (i.e., capsicum, garlic, eugenol, cinnamaldehyde curcuma, catechins, anethol or pinene), and in the modulation of metabolic regulation (capsicum, cinnamaldehyde, curcuma or garlic) may open the opportunity for future applications. However, stability of the product in the GI tract, description of the mechanisms of action and the impact of these changes on performance needs to be further demonstrated.

scholarly journals The holographic conformal manifold of 3d $$ \mathcal{N} $$ = 2 S-fold SCFTs

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Nikolay Bobev ◽  
Friðrik Freyr Gautason ◽  
Jesse van Muiden
Keyword(s):  
String Theory ◽  
Three Dimensional ◽  
Parameter Family ◽  
Global Symmetry ◽  
Maximal Supergravity ◽  
All Solutions ◽  
Operator Spectrum ◽  
Type Iib String Theory ◽  
Two Parameter

Abstract We employ a non-compact gauging of four-dimensional maximal supergravity to construct a two-parameter family of AdS4 J-fold solutions preserving $$ \mathcal{N} $$ N = 2 supersymmetry. All solutions preserve $$ \mathfrak{u} $$ u (1) × $$ \mathfrak{u} $$ u (1) global symmetry and in special limits we recover the previously known $$ \mathfrak{su} $$ su (2) × $$ \mathfrak{u} $$ u (1) invariant $$ \mathcal{N} $$ N = 2 and $$ \mathfrak{su} $$ su (2) × $$ \mathfrak{su} $$ su (2) invariant $$ \mathcal{N} $$ N = 4 J-fold solutions. This family of AdS4 backgrounds can be uplifted to type IIB string theory and is holographically dual to the conformal manifold of a class of three-dimensional S-fold SCFTs obtained from the $$ \mathcal{N} $$ N = 4 T [U(N)] theory of Gaiotto-Witten. We find the spectrum of supergravity excitations of the AdS4 solutions and use it to study how the operator spectrum of the three-dimensional SCFT depends on the exactly marginal couplings.

scholarly journals Dryland Food Security in Ethiopia: Current Status, Opportunities, and a Roadmap for the Future

2021 ◽  
Vol 13 (11) ◽  
pp. 6503
Author(s):  
Yu Peng ◽  
Hubert Hirwa ◽  
Qiuying Zhang ◽  
Guoqin Wang ◽  
Fadong Li
Keyword(s):  
Food Security ◽  
Current Status ◽  
Future Research ◽  
Systematic Research ◽  
Security Assessment ◽  
Security Issue ◽  
Sustainable Development Goal ◽  
Zero Hunger ◽  
The Impact

Given the impact of COVID-19 and the desert locust plague, the Ethiopian food security issue has once again received widespread attention. Its food crisis requires comprehensive and systematic research to achieve the United Nations Sustainable Development Goal of zero hunger. This review discusses the current situation and the causes of food security in Ethiopia. We focus on the challenges in the food security assessment field. The article lists seven typical causes of food insecurity and three roots of food security in Ethiopia. Long-term food security assessment and a comprehensive understanding and manageability for food security causes are considered as the main existing research challenges. Climate-resilient management, water management, and long-term ecosystem network monitoring and data mining are suggested as potential roadmap for future research.

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