scholarly journals UNITARITY OF NONCOMMUTATIVE FIELD THEORIES FROM STRING THEORY

2003 ◽  
Vol 18 (33n35) ◽  
pp. 2525-2532 ◽  
Author(s):  
ALESSANDRO TORRIELLI
Keyword(s):  
String Theory ◽  
Open String ◽  
Space Time ◽  
Bosonic String ◽  
Field Theories ◽  
Noncommutative Space ◽  
Quantum Field Theories ◽  
Quantum Field ◽  
Superstring Theory ◽  
Time Quantum

We improve the study of the lack of perturbative unitarity of noncommutative space-time quantum field theories derived from open string theory in electric backgrounds, enforcing the universality of the mechanism by which a tachyonic branch cut appears when the Seiberg-Witten limit freezes the string in an unstable vacuum. The main example is realized in the context of the on-shell four-tachyon amplitude of the bosonic string, and the dependence of the phenomenon on the brane-worldvolume dimension is analysed. We discuss the possibility of a proof in superstring theory, and finally mention the NCOS limit in this framework.

scholarly journals Emergent fields from hidden sectors

2021 ◽  
Vol 2105 (1) ◽  
pp. 012002
Author(s):  
Pascal Anastasopoulos
Keyword(s):  
String Theory ◽  
Particle Physics ◽  
Field Theories ◽  
Gauge Fields ◽  
Quantum Field Theories ◽  
Quantum Field

Abstract The present research proceeding aims at investigating/exploring/sharpening the phenomenological consequences of string theory and holography in particle physics and cosmology. We rely on and elaborate on the recently proposed framework whereby four-dimensional quantum field theories describe all interactions in Nature, and gravity is an emergent and not a fundamental force. New gauge fields, axions, and fermions, which can play the role of right-handed neutrinos, can also emerge in this framework. Preprint: UWThPh 2021-8

scholarly journals Space-Time Resolved Approach for Interacting Quantum Field Theories

2011 ◽  
Vol 106 (2) ◽  
Author(s):  
R. E. Wagner ◽  
M. R. Ware ◽  
B. T. Shields ◽  
Q. Su ◽  
R. Grobe
Keyword(s):  
Space Time ◽  
Field Theories ◽  
Quantum Field Theories ◽  
Quantum Field ◽  
Time Resolved

scholarly journals Tetrads in low-energy weak interactions

2018 ◽  
Vol 33 (33) ◽  
pp. 1850197 ◽  
Author(s):  
Alcides Garat
Keyword(s):  
Electron Scattering ◽  
Weak Interactions ◽  
Space Time ◽  
Muon Decay ◽  
Low Energy ◽  
Field Theories ◽  
Quantum Field Theories ◽  
Particle Interactions ◽  
Quantum Field ◽  
The Relationship

Tetrads are introduced in order to study the relationship between tetrad gauge states of space–time and particle interactions, specially in weak processes at low energy. Through several examples like inverse muon decay, elastic neutrino–electron scattering, it is explicitly shown how to assign to each vertex of the corresponding low-order Feynman diagram in a weak interaction, a particular set of tetrad vectors. The relationship between the tetrads associated to different vertices is exhibited explicitly to be generated by a SU(2) local tetrad gauge transformation. We are establishing a direct link between standard gauge and tetrad gauge states of space–time using the quantum field theories perturbative formulations.

scholarly journals The landscape and the multiverse: What’s the problem?

Synthese ◽  
2021 ◽  
Author(s):  
James Read ◽  
Baptiste Le Bihan
Keyword(s):  
String Theory ◽  
Quantum Gravity ◽  
Current Source ◽  
Field Theories ◽  
Quantum Field Theories ◽  
Quantum Field ◽  
The Past ◽  
Empirical Criterion ◽  
Scientific Status ◽  
Vast Range

AbstractAs a candidate theory of quantum gravity, the popularity of string theory has waxed and waned over the past four decades. One current source of scepticism is that the theory can be used to derive, depending upon the input geometrical assumptions that one makes, a vast range of different quantum field theories, giving rise to the so-called landscape problem. One apparent way to address the landscape problem is to posit the existence of a multiverse; this, however, has in turn drawn heightened attention to questions regarding the empirical testability and predictivity of string theory. We argue first that the landscape problem relies on dubious assumptions and does not motivate a multiverse hypothesis. Nevertheless, we then show that the multiverse hypothesis is scientifically legitimate and could be coupled to string theory for other empirical reasons. Looking at various cosmological approaches, we offer an empirical criterion to assess the scientific status of multiverse hypotheses.

scholarly journals Fractional Quantum Field Theory: From Lattice to Continuum

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Vasily E. Tarasov
Keyword(s):  
Field Theory ◽  
Fractional Order ◽  
Differential Operators ◽  
Dimensional Space ◽  
Space Time ◽  
Field Theories ◽  
Quantum Field Theories ◽  
Quantum Field ◽  
Field Equations ◽  
Lattice Space

An approach to formulate fractional field theories on unbounded lattice space-time is suggested. A fractional-order analog of the lattice quantum field theories is considered. Lattice analogs of the fractional-order 4-dimensional differential operators are proposed. We prove that continuum limit of the suggested lattice field theory gives a fractional field theory for the continuum 4-dimensional space-time. The fractional field equations, which are derived from equations for lattice space-time with long-range properties of power-law type, contain the Riesz type derivatives on noninteger orders with respect to space-time coordinates.

The Discrete and Continuous Quantum Field Theories and Natural Ultraviolet Cutting-off

2021 ◽  
Vol 24 (3) ◽  
pp. 280-291
Author(s):  
Alexander Shalyt-Margolin
Keyword(s):  
Black Hole ◽  
Space Time ◽  
Black Hole Thermodynamics ◽  
Field Theories ◽  
Quantum Field Theories ◽  
Quantum Field ◽  
Continuous Space

Based on the results from black hole thermodynamics at all energy scales, this work demonstrates that, both for the discrete QFT previously introduced by the author and for QFT in continuous space-time, there is a natural ultraviolet applicable boundary (cut-off) distant from the Planck scales. It is important that this boundary exists irrespective of the fact in which pattern, perturbative or non-perturbative mode, QFT is studied. Different inferences from the obtained results are discussed, some statements are revised.

scholarly journals THE SPACE–TIME ATTRIBUTE OF MATTER

1998 ◽  
Vol 13 (08) ◽  
pp. 651-658
Author(s):  
BORGE NODLAND
Keyword(s):  
Space Time ◽  
Field Theories ◽  
Specific Method ◽  
Quantum Field Theories ◽  
Quantum Field

We propose that space–time is fundamentally a property of matter, inseparable from it. This leads us to suggest that all properties of matter must be elevated to the same status as that of space–time in quantum field theories of matter. We suggest a specific method for extending field theories to accommodate this, and point out how this leads to the evolution of fields through channels other than the space–time channel.

QUANTUM FIELD THEORY ON NONCOMMUTATIVE SPACE–TIME: THE RELATION BETWEEN ULTRAVIOLET BEHAVIOUR, TOPOLOGY AND SYMMETRY

2001 ◽  
Vol 16 (04n06) ◽  
pp. 235-240
Author(s):  
M. CHAICHIAN ◽  
A. DEMICHEV ◽  
P. PREŠNAJDER
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Star Product ◽  
Space Time ◽  
Time Variable ◽  
Noncommutative Space ◽  
Quantum Field Theories ◽  
Quantum Field ◽  
Interaction Terms ◽  
Scalar Quantum

We study properties of a scalar quantum field theory on two-dimensional noncommutative space–times. We show that ultraviolet behaviour of a field theory on noncommutative spaces is sensitive to the topology of the space–time, namely to its compactness. The compactness of space-like coordinates implies discreteness of the time variable which leads to appearance of unphysical modes and violation of unitarity even in the absence of a star-product in the interaction terms. Thus, this conclusion holds also for other quantum field theories with discrete time.

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