LOCAL VACUUM EXCITATIONS IN STRONG ELECTROMAGNETIC FIELDS?

1988 ◽  
Vol 03 (07) ◽  
pp. 1751-1757 ◽  
Author(s):  
ANDREAS SCHÄFER ◽  
BERNDT MÜLLER ◽  
WALTER GREINER
Keyword(s):  
Electromagnetic Fields ◽  
Electric Fields ◽  
Gluon Condensate ◽  
Vacuum State ◽  
Heavy Ion ◽  
Energy Scale ◽  
Ion Collisions ◽  
Electron Positron ◽  
The Standard Model ◽  
Text Component

We discuss the possibility that strong electromagnetic fields might induce local changes in the vacuum state of the standard model and argue that such states could have all the necessary properties to explain the coincident electron-positron lines observed at GSI. Two specific ideas are investigated. The first relies on the assumption that the Higgs-vacuum state is nearly destabilized by radiative corrections, so that the electric fields produced in heavy ion collisions are strong enough to induce a local phase transition. The second one relies on vacuum changes in the QCD sector. We propose a scenario in which the gluon condensate acquires a [Formula: see text] component and argue that this could change the energy scale of QCD, i.e. ΛQCD.

scholarly journals Electron-Positron Vacuum Instability in Strong Electric Fields. Relativistic Semiclassical Approach

Universe ◽  
2021 ◽  
Vol 7 (4) ◽  
pp. 104
Author(s):  
Dmitry N. Voskresensky
Keyword(s):  
Electric Fields ◽  
Quantum Electrodynamics ◽  
Finite Size ◽  
Heavy Ion ◽  
Semiclassical Approach ◽  
Ion Collisions ◽  
Electron Positron ◽  
Lower Continuum ◽  
Strong Electric Fields ◽  
Spinless Boson

The instability of electron-positron vacuum in strong electric fields is studied. First, falling to the Coulomb center is discussed at Z>137/2 for a spinless boson and at Z>137 for electron. Subsequently, focus is concentrated on description of deep electron levels and spontaneous positron production in the field of a finite-size nucleus with the charge Z>Zcr≃170. Next, these effects are studied in application to the low-energy heavy-ion collisions. Subsequently, we consider phenomenon of “electron condensation” on levels of upper continuum crossed the boundary of the lower continuum ϵ=−m in the field of a supercharged nucleus with Z≫Zcr. Finally, attention is focused on many-particle problems of polarization of the quantum electrodynamics (QED) vacuum and electron condensation at ultra-short distances from a source of charge. We argue for a principal difference of cases, when the size of the source is larger than the pole size rpole, at which the dielectric permittivity of the vacuum reaches zero and smaller rpole. Some arguments are presented in favor of the logical consistency of QED. All of the problems are considered within the same relativistic semiclassical approach.

scholarly journals Charge-dependent flow as evidence of strong electromagnetic fields in heavy-ion collisions

2020 ◽  
Vol 35 (39) ◽  
pp. 2050324
Author(s):  
Andrea Dubla ◽  
Umut Gürsoy ◽  
Raimond Snellings
Keyword(s):  
Electromagnetic Fields ◽  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Experimental Characterization ◽  
Ion Collisions ◽  
Current State ◽  
Theoretical Predictions ◽  
Dependent Flow

The extremely large electromagnetic fields generated in heavy-ion collisions provide access to novel observables that are expected to constrain various key transport properties of the quark-gluon plasma and could help solve one of the outstanding puzzles in QCD: the strong CP problem. In this review we present a brief overview of the theoretical and experimental characterization of these electromagnetic fields. After reviewing the current state, emphasizing one of the observables — the charge-dependent flow — we discuss the various discrepancies between the measurements and theoretical predictions. Finally, to help resolve the discrepancies, we suggest new measurements and theoretical ideas.

scholarly journals Kinetic Approach to Pair Production in Strong Fields—Two Lessons for Applications to Heavy-Ion Collisions

Particles ◽  
2019 ◽  
Vol 2 (2) ◽  
pp. 166-179 ◽  
Author(s):  
David Blaschke ◽  
Lukasz Juchnowski ◽  
Andreas Otto
Keyword(s):  
Electric Fields ◽  
Heavy Ion Collisions ◽  
Particle Production ◽  
Heavy Ion ◽  
String Tension ◽  
Particle Number Density ◽  
Apparent Temperature ◽  
Particle Spectrum ◽  
Stochastic Field ◽  
Ion Collisions

The kinetic-equation approach to particle production in strong, time-dependent external fields is revisited and three limiting cases are discussed for different field patterns: the Sauter pulse, a harmonic pulse with a Gaussian envelope, and a Poisson-distributed stochastic field. It is shown that for transient subcritical electric fields E ( t ) a finite residual particle number density n ( ∞ ) would be absent if the field-dependence of the dynamical phase in the Schwinger source term would be neglected. In this case the distribution function of created particles follows the law f ( t ) ∼ E 2 ( t ) . Two lessons for particle production in heavy-ion collisions are derived from this exercise. First: the shorter the (Sauter-type) pulse, the higher the residual density of produced particles. Second: although the Schwinger process in a string-type field produces a non-thermal particle spectrum, a Poissonian distribution of the (fluctuating) strings produces a thermal spectrum with an apparent temperature that coincides with the Hawking–Unruh temperature for the mean value of the string tension.

Nonperturbative character of electron-positron pair production in relativistic heavy-ion collisions

1991 ◽  
Vol 66 (20) ◽  
pp. 2613-2616 ◽  
Author(s):  
Klaus Rumrich ◽  
Klaus Momberger ◽  
Gerhard Soff ◽  
Walter Greiner ◽  
Norbert Grün ◽  
...  
Keyword(s):  
Pair Production ◽  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Relativistic Heavy Ion Collisions ◽  
Ion Collisions ◽  
Electron Positron ◽  
Electron Positron Pair

scholarly journals Nuclear modification of prompt and non-prompt J/Ψ production in p-Pb collisions at √SNN = 5.02 TeV with ALICE

2018 ◽  
Vol 192 ◽  
pp. 00018
Author(s):  
Giuseppe Trombetta
Keyword(s):  
Nuclear Matter ◽  
Decay Channel ◽  
Hadron Collider ◽  
Heavy Ion ◽  
Energy Scale ◽  
Cold Nuclear Matter ◽  
Nuclear Modification ◽  
Ion Collisions ◽  
Central Rapidity ◽  
Theoretical Predictions

Various Cold Nuclear Matter (CNM) effects, such as nuclear shadowing or partonic energy loss, can modify the production of J/Ψ in heavy-ion collisions with respect to what is measured in elementary colliding systems. The study of p-Pb collisions at the Large Hadron Collider (LHC) energy scale represents a crucial tool to assess the influence of Cold Nuclear Matter on J/Ψ production in order to achieve a more correct interpretation of Pb-Pb collision results. The ALICE detector at the LHC is capable of reconstructing J/Ψ mesons at central rapidity through their e+e- decay channel down to zero transverse momentum (pT), and has measured the fraction of J/Ψ produced from the decay of beauty-flavoured hadrons (non-prompt J/Ψ) in p-Pb collisions down to pT = 1:3 GeV/c. In this paper, the results obtained by ALICE from the measurement of the prompt and non-prompt J/Ψ yields at mid-rapidity in p-Pb collisions at √SNN = 5.02 TeV will be discussed in comparison to different theoretical predictions including CNM effects.

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