Gravity Quantized In Dimension 4

2014 ◽  
Vol 4 (1) ◽  
pp. 298-391
Author(s):  
Beyram Torbrand
Keyword(s):  
Quantum Gravity ◽  
Cross Sections ◽  
Particle Physics ◽  
Critical Dimension ◽  
Einstein Gravity ◽  
Theoretical Physics ◽  
Simple Quantum

This is a sequel to the article 'A More or Less Well-Behaved Quantum Gravity Lagrangean in Dimension 4?' in Advanced Studies in Theoretical Physics, Torbrand Dhrif[6]. We give a simple Quantum Gravity Lagrangean that behaves well, up to the standards of particle physics. Feynman calculus for cross-sections, and the diagrams involved, should behave good. The action is naively renormalizable, has critical dimension and is invariant under scalings in dimension 4. It implies standard Einstein gravity for a massless graviton.

scholarly journals The NUMEN Project: Toward New Experiments with High-Intensity Beams

Universe ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 72
Author(s):  
Clementina Agodi ◽  
Antonio D. Russo ◽  
Luciano Calabretta ◽  
Grazia D’Agostino ◽  
Francesco Cappuzzello ◽  
...  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
High Intensity ◽  
Particle Physics ◽  
Nuclear Physics ◽  
High Sensitivity ◽  
Experimental Information ◽  
Double Charge Exchange ◽  
Superconducting Cyclotron ◽  
Double Charge

The search for neutrinoless double-beta (0νββ) decay is currently a key topic in physics, due to its possible wide implications for nuclear physics, particle physics, and cosmology. The NUMEN project aims to provide experimental information on the nuclear matrix elements (NMEs) that are involved in the expression of 0νββ decay half-life by measuring the cross section of nuclear double-charge exchange (DCE) reactions. NUMEN has already demonstrated the feasibility of measuring these tiny cross sections for some nuclei of interest for the 0νββ using the superconducting cyclotron (CS) and the MAGNEX spectrometer at the Laboratori Nazionali del Sud (LNS.) Catania, Italy. However, since the DCE cross sections are very small and need to be measured with high sensitivity, the systematic exploration of all nuclei of interest requires major upgrade of the facility. R&D for technological tools has been completed. The realization of new radiation-tolerant detectors capable of sustaining high rates while preserving the requested resolution and sensitivity is underway, as well as the upgrade of the CS to deliver beams of higher intensity. Strategies to carry out DCE cross-section measurements with high-intensity beams were developed in order to achieve the challenging sensitivity requested to provide experimental constraints to 0νββ NMEs.

scholarly journals Effective Scalar Potential in Asymptotically Safe Quantum Gravity

Universe ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 45
Author(s):  
Christof Wetterich
Keyword(s):  
Quantum Gravity ◽  
Top Quark ◽  
Particle Physics ◽  
Scalar Potential ◽  
Scalar Fields ◽  
The Standard Model ◽  
Scaling Potential ◽  
Realistic Description ◽  
The Masses ◽  
Dynamical Dark Energy

We compute the effective potential for scalar fields in asymptotically safe quantum gravity. A scaling potential and other scaling functions generalize the fixed point values of renormalizable couplings. The scaling potential takes a non-polynomial form, approaching typically a constant for large values of scalar fields. Spontaneous symmetry breaking may be induced by non-vanishing gauge couplings. We strengthen the arguments for a prediction of the ratio between the masses of the top quark and the Higgs boson. Higgs inflation in the standard model is unlikely to be compatible with asymptotic safety. Scaling solutions with vanishing relevant parameters can be sufficient for a realistic description of particle physics and cosmology, leading to an asymptotically vanishing “cosmological constant” or dynamical dark energy.

scholarly journals The Swampland Conjectures: A Bridge from Quantum Gravity to Particle Physics

Universe ◽  
2021 ◽  
Vol 7 (8) ◽  
pp. 273
Author(s):  
Mariana Graña ◽  
Alvaro Herráez
Keyword(s):  
Effective Field Theories ◽  
Quantum Gravity ◽  
Particle Physics ◽  
Effective Field ◽  
Low Energy ◽  
Field Theories ◽  
Neutrino Masses ◽  
Higgs Potential ◽  
Photon Mass ◽  
Effective Theories

The swampland is the set of seemingly consistent low-energy effective field theories that cannot be consistently coupled to quantum gravity. In this review we cover some of the conjectural properties that effective theories should possess in order not to fall in the swampland, and we give an overview of their main applications to particle physics. The latter include predictions on neutrino masses, bounds on the cosmological constant, the electroweak and QCD scales, the photon mass, the Higgs potential and some insights about supersymmetry.

Introduction

2021 ◽  
pp. 1-7
Author(s):  
Andrew Zangwill
Keyword(s):  
State Physics ◽  
Solid State ◽  
Symmetry Breaking ◽  
Particle Physics ◽  
Popular Media ◽  
Theoretical Physics ◽  
Solid State Physics ◽  
Scientific Enterprise ◽  
Big Ideas ◽  
Rules Of The Game

This chapter provides an overview of Anderson’s career and contrasts his speciality, the physics of the very many (solid-state physics), with the areas of physics that tend to appear in popular media—the physics of the very small (particle physics) and the physics of the very distant (astrophysics and cosmology). It compares Anderson’s physics skills to those of a chess grandmaster. The number of pieces (atoms and electrons) is so large that merely knowing the microscopic rules of the game is not enough to gain real understanding. There is a focus on the big ideas Anderson brought to the table—symmetry breaking, emergence, and complexity—and also his great interest in the cultural and political aspects of physics. The goal of the book is to help readers understand the magician-like skills Anderson brought to theoretical physics and the effect these had on his students, coworkers, community, and on scientific enterprise.

scholarly journals Hidden sector monopole dark matter with matter domination

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Michael L. Graesser ◽  
Jacek K. Osiński
Keyword(s):  
Dark Matter ◽  
Cross Sections ◽  
Particle Physics ◽  
Magnetic Monopoles ◽  
Number Density ◽  
Pure Radiation ◽  
Hidden Sector ◽  
Equilibrium Dynamics ◽  
Thermal Histories ◽  
Relic Abundance

Abstract The thermal freeze-out mechanism for relic dark matter heavier than O(10 − 100 TeV) requires cross-sections that violate perturbative unitarity. Yet the existence of dark matter heavier than these scales is certainly plausible from a particle physics perspective, pointing to the need for a non-thermal cosmological history for such theories. Topological dark matter is a well-motivated scenario of this kind. Here the hidden-sector dark matter can be produced in abundance through the Kibble-Zurek mechanism describing the non-equilibrium dynamics of defects produced in a second order phase transition. We revisit the original topological dark matter scenario, focusing on hidden-sector magnetic monopoles, and consider more general cosmological histories. We find that a monopole mass of order (1–105) PeV is generic for the thermal histories considered here, if monopoles are to entirely reproduce the current abundance of dark matter. In particular, in a scenario involving an early era of matter domination, the monopole number density is always less than or equal to that in a pure radiation dominated equivalent provided a certain condition on critical exponents is satisfied. This results in a larger monopole mass needed to account for a fixed relic abundance in such cosmologies.

scholarly journals EXACT SOLUTIONS TO THE TWO-DIMENSIONAL BF AND YANG–MILLS THEORIES IN THE LIGHT-CONE GAUGE

2002 ◽  
Vol 17 (11) ◽  
pp. 1491-1502 ◽  
Author(s):  
MITSUO ABE ◽  
NOBORU NAKANISHI
Keyword(s):  
Exact Solution ◽  
Quantum Gravity ◽  
Light Cone ◽  
Lagrangian Density ◽  
Critical Dimension ◽  
Two Dimensional ◽  
Light Cone Gauge ◽  
Yang Mills ◽  
Bf Theory ◽  
Conformal Gauge

It is shown that the BRS (= Becchi–Rouet–Stora)-formulated two-dimensional BF theory in the light-cone gauge (coupled with chiral Dirac fields) is solved very easily in the Heisenberg picture. The structure of the exact solution is very similar to that of the BRS-formulated two-dimensional quantum gravity in the conformal gauge. In particular, the BRS Noether charge has anomaly. Based on this fact, a criticism is made on the reasoning of Kato and Ogawa, who derived the critical dimension D=26 of string theory on the basis of the anomaly of the BRS Noether charge. By adding the [Formula: see text] term to the BF-theory Lagrangian density, the exact solution to the two-dimensional Yang–Mills theory is also obtained.

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