scholarly journals Aspects of high energy scattering

2020 ◽  
Author(s):  
Chris White
Keyword(s):  
Graduate Students ◽  
High Energy ◽  
Field Theories ◽  
Quantum Field Theories ◽  
Quantum Field ◽  
Energy Limit ◽  
High Energy Limit ◽  
High Energy Scattering ◽  
Widespread Interest ◽  
Generic Behaviour

Scattering amplitudes in quantum field theories are of widespread interest, due to a large number of theoretical and phenomenological applications. Much is known about the possible behaviour of amplitudes, that is independent of the details of the underlying theory. This knowledge is often neglected in modern QFT courses, and the aim of these notes - aimed at graduate students - is to redress this. We review the possible singularities that amplitudes can have, before examining the generic behaviour that can arise in the high-energy limit. Finally, we illustrate the results using examples from QCD and gravity.

scholarly journals Formfactors of Relativistic Composite Particle Interactions in Unified Nonlinear Spinorfield Models

1985 ◽  
Vol 40 (7) ◽  
pp. 752-773
Author(s):  
H. Stumpf
Keyword(s):  
Composite Particle ◽  
Particle Interaction ◽  
High Energy ◽  
Field Theories ◽  
Quantum Field Theories ◽  
Statistical Interpretation ◽  
Quantum Field ◽  
Mapping Procedure ◽  
Effective Dynamics ◽  
Rough Approximation

Unified nonlinear spinorfield models are self-regularizing quantum field theories in which all observable (elementary and non-elementary) particles are assumed to be bound states of fermionic preon fields. Due to their large masses the preons themselves are confined and below the threshold of preon production the effective dynamics of the model is only concerned with bound state reactions. In preceding papers a functional energy representation, the statistical interpretation and the dynamical equations were derived and the effective dynamics for preon-antipreon boson states and three preon-fermion states (with corresponding anti-fermions) was studied in the low energy limit. The transformation of the functional energy representation of the spinorfield into composite particle functional operators produced a hierarchy of effective interactions at the composite particle level, the leading terms of which are identical with the functional energy representation of a phenomenological boson-fermion coupling theory. In this paper these calculations are extended into the high energy range. This leads to formfactors for the composite particle interaction terms which are calculated in a rough approximation and which in principle are observable. In addition, the mathematical and physical interpretation of nonlocal quantum field theories and the meaning of the mapping procedure, its relativistic invariance etc. are discussed.

scholarly journals May the four be with you: novel IR-subtraction methods to tackle NNLO calculations

2021 ◽  
Vol 81 (3) ◽  
Author(s):  
W. J. Torres Bobadilla ◽  
G. F. R. Sborlini ◽  
P. Banerjee ◽  
S. Catani ◽  
A. L. Cherchiglia ◽  
...  
Keyword(s):  
High Energy Physics ◽  
High Energy ◽  
Higher Order ◽  
Field Theories ◽  
Quantum Field Theories ◽  
Quantum Field ◽  
Link Type ◽  
Mathematical Properties ◽  
Energy Physics ◽  
The Way

AbstractIn this manuscript, we report the outcome of the topical workshop: paving the way to alternative NNLO strategies (https://indico.ific.uv.es/e/WorkStop-ThinkStart_3.0), by presenting a discussion about different frameworks to perform precise higher-order computations for high-energy physics. These approaches implement novel strategies to deal with infrared and ultraviolet singularities in quantum field theories. A special emphasis is devoted to the local cancellation of these singularities, which can enhance the efficiency of computations and lead to discover novel mathematical properties in quantum field theories.

scholarly journals CHILD UNIVERSE UV REGULARIZATION?

2008 ◽  
Vol 17 (03n04) ◽  
pp. 551-555 ◽  
Author(s):  
E. I. GUENDELMAN
Keyword(s):  
Black Hole ◽  
Energy Density ◽  
High Energy ◽  
High Energy Density ◽  
Field Theories ◽  
Minimum Length ◽  
Quantum Field Theories ◽  
Quantum Field ◽  
Gravitational Effects ◽  
Black Hole Evaporation

It is argued that high energy density excitations, responsible for UV divergences in quantum field theories, including quantum gravity, are likely to be the source of child universes which carry them out of the original space–time. This decoupling prevents the high UV excitations from having any influence on physical amplitudes. Child universe production could therefore be responsible for UV regularization in quantum field theories which take into account gravitational effects. Finally, we discuss child universe production in the last stages of black hole evaporation, the prediction of the absence of trans-Planckian primordial perturbations, the connection with the minimum length hypothesis, and in particular the connection with the maximal curvature hypothesis.

FRACTIONAL FIELD THEORIES FROM MULTI-DIMENSIONAL FRACTIONAL VARIATIONAL PROBLEMS

2008 ◽  
Vol 05 (06) ◽  
pp. 863-892 ◽  
Author(s):  
RAMI AHMAD EL-NABULSI
Keyword(s):  
Differential Equations ◽  
Fractional Calculus ◽  
Fractional Differential Equations ◽  
High Energy Physics ◽  
Wave Theory ◽  
High Energy ◽  
Field Theories ◽  
Quantum Field Theories ◽  
Quantum Field ◽  
Fractional Differential

Fractional calculus has recently attracted considerable attention. In particular, various fractional differential equations are used to model nonlinear wave theory that arises in many different areas of physics such as Josephson junction theory, field theory, theory of lattices, etc. Thus one may expect fractional calculus, in particular fractional differential equations, plays an important role in quantum field theories which are expected to satisfy fractional generalization of Klein–Gordon and Dirac equations. Until now, in high-energy physics and quantum field theories the derivative operator has only been used in integer steps. In this paper, we want to extend the idea of differentiation to arbitrary non-integers steps. We will address multi-dimensional fractional action-like problems of the calculus of variations where fractional field theories and fractional differential Dirac operators are constructed.

scholarly journals High Energy Scattering of Non-Critical Strings

1997 ◽  
Vol 12 (06) ◽  
pp. 1253-1263 ◽  
Author(s):  
Kenichiro Aoki ◽  
Eric D'Hoker
Keyword(s):  
Central Charge ◽  
String Tension ◽  
High Energy ◽  
Tree Level ◽  
Energy Limit ◽  
Electrostatic Problem ◽  
High Energy Limit ◽  
On Line ◽  
High Energy Scattering ◽  
Branch Cuts

We summarize recent work, in which we consider scattering amplitudes of non-critical strings in the limit where the energy of all external states is large compared to the string tension. We show that the high energy limit is dominated by a saddle point that can be mapped onto an electrostatic equilibrium configuration of an assembly of charges associated with the external states, together with a density of charges arising from the Liouville field. The Liouville charges accumulate on line segments, which produce quadratic branch cuts on the worldsheet. The electrostatic problem is solved for string tree level in terms of hyperelliptic integrals and is given explicitly for the 3- and 4-point functions. For generic values of the central charge, the high energy limit behaves in a string-like fashion, with exponential energy dependence.

scholarly journals WORMHOLES AND CHILD UNIVERSES

2010 ◽  
Vol 19 (08n10) ◽  
pp. 1357-1364 ◽  
Author(s):  
E. I. GUENDELMAN
Keyword(s):  
Quantum Gravity ◽  
High Energy ◽  
High Energy Density ◽  
Field Theories ◽  
Minimum Length ◽  
Quantum Field Theories ◽  
Quantum Field ◽  
Classical Level ◽  
Gravitational Effects ◽  
Kaluza Klein

Evidence to the case that classical gravitation provides the clue to make sense out of quantum gravity is presented. The key observation is the existence in classical gravitation of child universe solutions or "almost" solutions, "almost" because of some singularity problems. The difficulties of these child universe solutions that are due to their generic singularity problems will be very likely be cured by quantum effects, just like for example "almost" instanton solutions are made relevant in gauge theories with the breaking of conformal invariance. Some well-motivated modifcations of general relativity where these singularity problems are absent even at the classical level are discussed. High energy density excitations, responsible for UV divergences in quantum field theories, including quantum gravity, are likely to be the source of child universes which carry them out of the original space–time. This decoupling could prevent these high UV excitations from having any influence on physical amplitudes. Child universe production could therefore be responsible for UV regularization in quantum field theories which take into account semiclassically gravitational effects. Child universe production in the last stages of black hole evaporation, the prediction of absence of trans-Planckian primordial perturbations, connection to the minimum length hypothesis, and in particular the connection to the maximal curvature hypothesis are discussed. Some discussion of superexcited states in the case these states such as Kaluza–Klein excitations are carried out. Finally, the possibility of obtaining "string like" effects from the wormholes associated with the child universes is discussed.

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