First measurement of the K−n →Λπ− non-resonant transition amplitude below threshold

Quantum mechanics

10.1093/oso/9780198802877.003.0002 ◽

2018 ◽

Author(s):

Michael Kachelriess

Keyword(s):

Field Theory ◽

Quantum Field Theory ◽

Quantum Mechanics ◽

Relativistic Quantum ◽

Transition Amplitude ◽

External Source ◽

Quantum Field ◽

Damping Term ◽

Relativistic Quantum Theory ◽

Generating Functional

After a brief review of the operator approach to quantum mechanics, Feynmans path integral, which expresses a transition amplitude as a sum over all paths, is derived. Adding a linear coupling to an external source J and a damping term to the Lagrangian, the ground-state persistence amplitude is obtained. This quantity serves as the generating functional Z[J] for n-point Green functions which are the main target when studying quantum field theory. Then the harmonic oscillator as an example for a one-dimensional quantum field theory is discussed and the reason why a relativistic quantum theory should be based on quantum fields is explained.

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Low Energy Antikaon-nucleon/nuclei interaction studies by AMADEUS

EPJ Web of Conferences ◽

10.1051/epjconf/201919901014 ◽

2019 ◽

Vol 199 ◽

pp. 01014

Author(s):

K. Piscicchia ◽

M. Bazzi ◽

G. Belloti ◽

A. M. Bragadireanu ◽

D. Bosnar ◽

...

Keyword(s):

Cross Sections ◽

Transition Amplitude ◽

Nuclear Interaction ◽

Branching Ratios ◽

Analysis Procedure ◽

Low Energy ◽

Carbon Target ◽

Pure Carbon ◽

Nuclear Targets ◽

Mass Spectroscopic Study

The AMADEUS experiment at the DAΦNE collider of LNF-INFN deals with the investigation of the at-rest, or low-momentum, K− interactions in light nuclear targets, with the aim to constrain the low energy QCD models in the strangeness sector. The 0 step of the experiment consisted in the reanalysis of the 2004/2005 KLOE data, exploiting K− absorptions in H, 4He, 9Be and 12C, leading to the first invariant mass spectroscopic study with very low momentum (about 100 MeV) in-flight K− captures. With AMADEUS step 1 a dedicated pure Carbon target was implemented in the central region of the KLOE detector, providing a high statistic sample of pure at-rest K− nuclear interaction. The first measurement of the non-resonant transition amplitude $\left| {{A_{{K^ - }n \to \Lambda {\pi ^ - }}}} \right|$ at $\sqrt s = 33\,MeV$ below the K̄N threshold is presented, in relation with the Λ(1405) properties studies. The analysis procedure adopted in the serarch for K− multi-nucleon absorption cross sections and Branching Ratios will be also described.

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A Complete CDW Theory for the Single Ionization of Multielectronic Atoms by Bare Ion Impact

Atoms ◽

10.3390/atoms9010003 ◽

2021 ◽

Vol 9 (1) ◽

pp. 3

Author(s):

Juan M. Monti ◽

Michele A. Quinto ◽

Roberto D. Rivarola

Keyword(s):

Transition Amplitude ◽

Emission Spectra ◽

Heavy Ion ◽

Distorted Wave ◽

Single Ionization ◽

Complete Form ◽

Active Electron ◽

Ion Impact ◽

Range Part ◽

The Continuum

A complete form of the post version of the continuum distorted wave (CDW) theory is used to investigate the single ionization of multielectronic atoms by fast bare heavy ion beams. The influence of the non-ionized electrons on the dynamic evolution is included through a residual target potential considered as a non-Coulomb central potential through a GSZ parametric one. Divergences found in the transition amplitude containing the short-range part of the target potential are avoided by considering, in that term exclusively, an eikonal phase instead of the continuum factor as the initial channel distortion function. In this way, we achieve the inclusion of the interaction between the target active electron and the residual target, giving place to a more complete theory. The present analysis is supported by comparisons with existing experimental electron emission spectra and other distorted wave theories.

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