QFT Derivation of the Decay Law of an Unstable Particle with Nonzero Momentum

We present a quantum field theoretical derivation of the nondecay probability of an unstable particle with nonzero three-momentum p. To this end, we use the (fully resummed) propagator of the unstable particle, denoted as S, to obtain the energy probability distribution, called dSp(E), as the imagin...

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Main Author: Francesco Giacosa
Format: Article
Language:English
Published: Wiley 2018-01-01
Series:Advances in High Energy Physics
Online Access:http://dx.doi.org/10.1155/2018/4672051
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author Francesco Giacosa
author_facet Francesco Giacosa
author_sort Francesco Giacosa
collection DOAJ
description We present a quantum field theoretical derivation of the nondecay probability of an unstable particle with nonzero three-momentum p. To this end, we use the (fully resummed) propagator of the unstable particle, denoted as S, to obtain the energy probability distribution, called dSp(E), as the imaginary part of the propagator. The nondecay probability amplitude of the particle S with momentum p turns out to be, as usual, its Fourier transform: aSp(t)=∫mth2+p2∞dEdSp(E)e-iEt (mth is the lowest energy threshold in the rest frame of S and corresponds to the sum of masses of the decay products). Upon a variable transformation, one can rewrite it as aSp(t)=∫mth∞dmdS0(m)e-imth2+p2t [here, dS0(m)≡dS(m) is the usual spectral function (or mass distribution) in the rest frame]. Hence, the latter expression, previously obtained by different approaches, is here confirmed in an independent and, most importantly, covariant QFT-based approach. Its consequences are not yet fully explored but appear to be quite surprising (such as the fact that the usual time-dilatation formula does not apply); thus its firm understanding and investigation can be a fruitful subject of future research.
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spelling doaj-art-e971255fec2c43a6b533a326e8b26de92025-02-03T01:31:40ZengWileyAdvances in High Energy Physics1687-73571687-73652018-01-01201810.1155/2018/46720514672051QFT Derivation of the Decay Law of an Unstable Particle with Nonzero MomentumFrancesco Giacosa0Institute of Physics, Jan-Kochanowski University, Ul. Swietokrzyska 15, 25-406 Kielce, PolandWe present a quantum field theoretical derivation of the nondecay probability of an unstable particle with nonzero three-momentum p. To this end, we use the (fully resummed) propagator of the unstable particle, denoted as S, to obtain the energy probability distribution, called dSp(E), as the imaginary part of the propagator. The nondecay probability amplitude of the particle S with momentum p turns out to be, as usual, its Fourier transform: aSp(t)=∫mth2+p2∞dEdSp(E)e-iEt (mth is the lowest energy threshold in the rest frame of S and corresponds to the sum of masses of the decay products). Upon a variable transformation, one can rewrite it as aSp(t)=∫mth∞dmdS0(m)e-imth2+p2t [here, dS0(m)≡dS(m) is the usual spectral function (or mass distribution) in the rest frame]. Hence, the latter expression, previously obtained by different approaches, is here confirmed in an independent and, most importantly, covariant QFT-based approach. Its consequences are not yet fully explored but appear to be quite surprising (such as the fact that the usual time-dilatation formula does not apply); thus its firm understanding and investigation can be a fruitful subject of future research.http://dx.doi.org/10.1155/2018/4672051
spellingShingle Francesco Giacosa
QFT Derivation of the Decay Law of an Unstable Particle with Nonzero Momentum
Advances in High Energy Physics
title QFT Derivation of the Decay Law of an Unstable Particle with Nonzero Momentum
title_full QFT Derivation of the Decay Law of an Unstable Particle with Nonzero Momentum
title_fullStr QFT Derivation of the Decay Law of an Unstable Particle with Nonzero Momentum
title_full_unstemmed QFT Derivation of the Decay Law of an Unstable Particle with Nonzero Momentum
title_short QFT Derivation of the Decay Law of an Unstable Particle with Nonzero Momentum
title_sort qft derivation of the decay law of an unstable particle with nonzero momentum
url http://dx.doi.org/10.1155/2018/4672051
work_keys_str_mv AT francescogiacosa qftderivationofthedecaylawofanunstableparticlewithnonzeromomentum