scholarly journals Quantum field-theoretical description of neutrino and neutral kaon oscillations

2018 ◽  
Vol 33 (13) ◽  
pp. 1850075 ◽  
Author(s):  
Igor P. Volobuev
Keyword(s):  
Plane Waves ◽  
Neutral Kaon ◽  
Theoretical Description ◽  
Matrix Formalism ◽  
Quantum Field ◽  
Time Intervals ◽  
Standard Quantum ◽  
Mass Eigenstates ◽  
Quantum Mechanical Description ◽  
S Matrix

It is shown that the neutrino and neutral kaon oscillation processes can be consistently described in quantum field theory using only plane waves of the mass eigenstates of neutrinos and neutral kaons. To this end, the standard perturbative S-matrix formalism is modified so that it can be used for calculating the amplitudes of the processes passing at finite distances and finite time intervals. The distance-dependent and time-dependent parts of the amplitudes of the neutrino and neutral kaon oscillation processes are calculated and the results turn out to be in accordance with those of the standard quantum mechanical description of these processes based on the notion of neutrino flavor states and neutral kaon states with definite strangeness. However, the physical picture of the phenomena changes radically: now, there are no oscillations of flavor or definite strangeness states, but, instead of it, there is interference of amplitudes due to different virtual mass eigenstates.

scholarly journals Description of processes passing at finite space and time intervals in the framework of QFT

2019 ◽  
Vol 222 ◽  
pp. 01009
Author(s):  
Vadim Egorov ◽  
Igor Volobuev
Keyword(s):  
Plane Waves ◽  
Neutral Kaon ◽  
Pion Decay ◽  
Momentum Representation ◽  
Time Intervals ◽  
Final Particle ◽  
New Approach ◽  
Space And Time ◽  
Feynman Rules ◽  
Finite Space

We consider a new approach to the description in the framework of QFT of processes passing at finite space and time intervals. The formalism is based on the Feynman diagram technique in the coordinate representation, in which the rules of passing to the momentum representation are modified in accordance with the experimental setup of neutrino oscillation experiments. In effect, only the propagators of particles in the momentum representation are modified, while all the other standard Feynman rules in the momentum representation remain the same. Since the initial and final particle states are described by plane waves, the approach does not need the use of wave packets, which greatly simplifies the calculations of amplitudes. Taking as examples the processes of displaced pion decay, neutral kaon and neutrino oscillations we show that the approach under consideration correctly reproduces the known standard results.

Quantum Field Theory Beyond the S-Matrix Formalism

2020 ◽  
Vol 51 (4) ◽  
pp. 614-618
Author(s):  
I. P. Volobuev ◽  
V. O. Egorov
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Matrix Formalism ◽  
Quantum Field ◽  
S Matrix

scholarly journals Some Features of the Direct and Inverse Double-Compton Effect as Applied to Astrophysics

Physics ◽  
2021 ◽  
Vol 3 (4) ◽  
pp. 1167-1174
Author(s):  
Viktor Dubrovich ◽  
Timur Zalialiutdinov
Keyword(s):  
Cross Section ◽  
Spectral Characteristics ◽  
Plane Waves ◽  
Detailed Balance ◽  
Infrared Divergence ◽  
Matrix Formalism ◽  
X Ray ◽  
S Matrix ◽  
Infrared Divergences ◽  
Photon Source

In the present paper, the process of inverse double-Compton (IDC) scattering is considered in the context of astrophysical applications. It is assumed that the two hard X-ray photons emitted from an astrophysical source are scattered on a free electron and converted into a single soft photon of optical range. Using the QED S-matrix formalism for the derivation of a cross-section of direct double-Compton (DDC) scattering and assuming detailed balance conditions, an analytical expression for the cross-section of the IDC process is presented. It is shown that at fixed energies of incident photons, the inverse cross-section has no infrared divergences, and its behavior is completely defined by the spectral characteristics of the photon source itself, in particular by the finite interaction time of radiation with an electron. Thus, even for the direct process, the problem of resolving infrared divergence actually refers to a real physical source of radiation in which photons are never actually plane waves. As a result, the physical frequency profile of the scattered radiation for DDC as well as for IDC processes is a function of both the intensity and line shape of the incident photon field.

scholarly journals Classical black hole scattering from a worldline quantum field theory

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Gustav Mogull ◽  
Jan Plefka ◽  
Jan Steinhoff
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Black Hole ◽  
Quantum Field ◽  
Expectation Values ◽  
Path Integral Representation ◽  
S Matrix ◽  
Feynman Rules ◽  
Definition Of ◽  
Three Body

Abstract A precise link is derived between scalar-graviton S-matrix elements and expectation values of operators in a worldline quantum field theory (WQFT), both used to describe classical scattering of black holes. The link is formally provided by a worldline path integral representation of the graviton-dressed scalar propagator, which may be inserted into a traditional definition of the S-matrix in terms of time-ordered correlators. To calculate expectation values in the WQFT a new set of Feynman rules is introduced which treats the gravitational field hμν(x) and position $$ {x}_i^{\mu}\left({\tau}_i\right) $$ x i μ τ i of each black hole on equal footing. Using these both the 3PM three-body gravitational radiation 〈hμv(k)〉 and 2PM two-body deflection $$ \Delta {p}_i^{\mu } $$ Δ p i μ from classical black hole scattering events are obtained. The latter can also be obtained from the eikonal phase of a 2 → 2 scalar S-matrix, which we show corresponds to the free energy of the WQFT.

Lecture on SUSY Gauge Theories and Integrable Systems

1997 ◽  
Vol 11 (26n27) ◽  
pp. 3093-3124
Author(s):  
A. Marshakov
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Integrable Systems ◽  
Gauge Theories ◽  
Toda Chain ◽  
Quantum Field ◽  
Standard Quantum ◽  
Integrable Equations ◽  
Complex Curves ◽  
Periodic Toda Chain

I consider main features of the formulation of the finite-gap solutions to integrable equations in terms of complex curves and generating 1-differential. The example of periodic Toda chain solutions is considered in detail. Recently found exact nonperturbative solutions to [Formula: see text] SUSY gauge theories are formulated using the methods of the theory of integrable systems and where possible the parallels between standard quantum field theory results and solutions to the integrable systems are discussed.

INTEGRABLE FIELD THEORY OF THE q-STATE POTTS MODEL WITH 0

1992 ◽  
Vol 07 (21) ◽  
pp. 5317-5335 ◽  
Author(s):  
LEUNG CHIM ◽  
ALEXANDER ZAMOLODCHIKOV
Keyword(s):  
Field Theory ◽  
Potts Model ◽  
Density Operator ◽  
Size Distributions ◽  
Quantum Field ◽  
Particle Content ◽  
Integrable Field Theory ◽  
Percolation Problem ◽  
S Matrix ◽  
Integrable Field

Two-dimensional quantum field theory obtained by perturbing the q-state Potts-model CFT (0<q<4) with the energy-density operator Φ(2, 1) is shown to be integrable. The particle content of this QFT is conjectured and the factorizable S matrix is proposed. The limit q→1 is related to the isotropic-percolation problem in 2D and so we make a few predictions about the size distributions of the percolating clusters in the scaling domain.

S-matrix formalism of transmission through two quantum billiards coupled by a waveguide

2005 ◽  
Vol 38 (49) ◽  
pp. 10647-10661 ◽  
Author(s):  
Almas F Sadreev ◽  
Evgeny N Bulgakov ◽  
Ingrid Rotter
Keyword(s):  
Matrix Formalism ◽  
S Matrix
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