scholarly journals Hadron Contribution to Vacuum Polarisation

Author(s):  
M. Davier ◽  
A. Hoecker ◽  
B. Malaescu ◽  
Z. Zhang
Keyword(s):  
Author(s):  
Jonathan Gratus ◽  
Paul Kinsler ◽  
Martin W. McCall

A careful examination of the fundamentals of electromagnetic theory shows that due to the underlying mathematical assumptions required for Stokes' Theorem, global charge conservation cannot be guaranteed in topologically non-trivial spacetimes. However, in order to break the charge conservation mechanism we must also allow the electromagnetic excitation fields D, H to possess a gauge freedom, just as the electromagnetic scalar and vector potentials $\varphi$ and A do. This has implications for the treatment of electromagnetism in spacetimes where black holes both form and then evaporate, as well as extending the possibilities for treating vacuum polarisation. Using this gauge freedom of D, H we also propose an alternative to the accepted notion that a charge passing through a wormhole necessarily leads to an additional (effective) charge on the wormhole's mouth.


2014 ◽  
Author(s):  
Gregorio Herdoiza ◽  
Hanno Horch ◽  
Benjamin Jaeger ◽  
Hartmut Wittig

2020 ◽  
Vol 234 ◽  
pp. 01016
Author(s):  
Hartmut Wittig ◽  
Antoine Gérardin ◽  
Marco Cè ◽  
Georg von Hippel ◽  
Ben Hörz ◽  
...  

The persistent discrepancy of about 3.5 standard deviations between the experimental measurement and the Standard Model prediction for the muon anomalous magnetic moment, aµ, is one of the most promising hints for the possible existence of new physics. Here we report on our lattice QCD calculation of the hadronic vacuum polarisation contribution $ a_\mu ^{{\rm{hvp}}} $, based on gauge ensembles with Nf = 2 + 1 flavours of O(a) improved Wilson quarks. We address the conceptual and numerical challenges that one encounters along the way to a sub-percent determination of the hadronic vacuum polarisation contribution. The current status of lattice calculations of $ a_\mu ^{{\rm{hvp}}} $ is presented by performing a detailed comparison with the results from other groups.


2018 ◽  
Vol 175 ◽  
pp. 10006 ◽  
Author(s):  
Renwick Hudspith ◽  
Randy Lewis ◽  
Kim Maltman ◽  
Eigo Shintani

We present our result for the strong coupling constant computed from the u-d vector Hadronic Vacuum Polarisation function. We use nf = 2 + 1 flavours of Domain Wall fermions at 3 lattice spacings, generated by the RBC-UKQCD collaboration. We identify several possible pitfalls in this method for determining the coupling and illustrate how to resolve them.


2012 ◽  
Vol 14 ◽  
pp. 127-140 ◽  
Author(s):  
THOMAS HEINZL

This contribution presents an overview of fundamental QED processes in the presence of an external field produced by an ultra-intense laser. The discussion focusses on the basic intensity effects on vacuum polarisation and the prospects for their observation. Some historical remarks are added where appropriate.


1986 ◽  
Vol 451 (4) ◽  
pp. 679-700 ◽  
Author(s):  
I. Beltrami ◽  
B. Aas ◽  
W. Beer ◽  
G. De Chambrier ◽  
P.F.A. Goudsmit ◽  
...  

2016 ◽  
Vol 17 (8) ◽  
pp. 1937-1954 ◽  
Author(s):  
Jonas Lampart ◽  
Mathieu Lewin

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