ELFT HÍRADÓ

[mcsete AT physx.u-szeged.hu]

Seminar

Speaker: Prof. Sándor Varró
group leader, leading scientist
ELI-ALPS (Attosecond Light Pulse Source),
ELI-HU Non-profit Ltd., Szeged, Hungary.

Date: 3pm, 10, April (Wednesday) 2024
Location: SZTE TTIK FI, Budó auditorium & online
https://join.skype.com/KKdu6TH7izni

Title:
Plasmons, Massive Photons and the Hypothetical X17 Particle.

Abstract:
Recent observations of anomalous angular correlations (called ATOMKI  
nuclear anomaly) of electron-positron pairs in several reactions (like  
7Li(p,e-e+)8Be) have indicated the existence of a neutral boson of   
rest mass of about 17 MeV/c^2, called the X17 particle [1]. Similarly,  
the results of another set of experiments on photon pair spectra  
around the invariant mass 38 MeV/c^2, can be interpreted by assuming  
the existence of the so-called E38 particle [2]. There have been  
various attempts to theoretically determine the invariant masses of  
these particles, like the fifth force interpretation, or by going  
beyond the standard model. In a special meson theory, where the strong  
force plays only a role of a background field, new kinds of  
quark-antiquark electromagnetic bound states have been introduced, as  
possible candidates for the X17 and E38 particles [3]. In the present  
talk we merely rely on quantum electrodynamics considerations, and use  
the exact solutions of the Dirac equation of the system of a charged  
particle and quantized electromagnetic plane waves. These solutions  
have long been known and used for the description of high-harmonic  
generation in multiphoton Compton scattering [4].
After a brief overview on massive photons, we show that the mentioned  
non-perturbative solutions, applied to the proton, lead to an  
invariant mass term 17.0087 MeV/c^2 for the dressed radiation [5].  
This value is in a very good agreement with the measured invariant  
mass of  the hypothetical X17 vector boson [1]. By applying our scheme  
for the udd quarks of the neutrons, a similar analytic formula has  
also been derived, which gives 37.9938 MeV/c^2 for the invariant mass  
[5], corresponding to the hypothetical E38 particle [2]. Besides the  
Sommerfeld fine structure constant and the nucleon masses, both of our  
derived formulas [5] contain merely some statistical factors, which  
come out by straightforward calculations. These formulas do not  
contain any adjustable parameters, like the coupling constants or the  
flux tube radius used in other theories [3].
In our talk we also wish to illustrate that, besides the theory of  
attosecond physics, multiphoton strong-field and quantum optics  
methods, applied to relativistic systems, are also useful for  
understanding some phenomena of recent interests in nuclear and  
particle physics.

References.
[1] Krasznahorkay A J, et al., Observation of anomalous internal pair  
creation in 8Be : a possible indication of a light, neutral boson.  
Phys. Rev. Lett. 116, 042501 (2016).
[2] Abraamyan K, Austin C, Baznat M, , Check of the structure in  
photon pairs spectra at the invariant mass of about 38 MeV/c2. EJP Web  
of Conferences 204, 08004 (2019).
[3] Wong Ch-Y, Open string QED meson description of the X17 particle  
and dark matter. JHEP08, 165 (2022).
[4] Varró S, Theoretical study of the interaction of free electrons  
with intense light. (Ph.D. dissertation, 1981). Hungarian Physical  
Journal XXXI, 399-454 (1983).
[5] Varró S, Proposal for an electromagnetic mass formula for the X17  
particle. Universe  2024, 10, 86.  
[https://doi.org/10.3390/universe10020086]. [Based on the talk  
presented at  ISMD 2023 - 52nd International Symposium on  
Multiparticle Dynamics, August 21-25 2023 - Gyöngyös, Hungary.      
This article belongs to the Special Issue ?Multiparticle Dynamics?,  
Edited by Csörgö T, Csanád M and Novák T;  
https://www.mdpi.com/journal/universe/special_issues/3R2XYDMCV9].


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