Leptogenesis driven by a Majoron

Abstract

We propose a leptogenesis scenario where baryon asymmetry generation is assisted by the kinetic motion of the Majoron, <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>J</a:mi></a:math>, in the process of lepton-number violating inverse decays of a right-handed neutrino, <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>N</c:mi></c:math>. We investigate two distinct scenarios depending on the sources of a Majoron kinetic motion: (1) the misalignment mechanism, and (2) the kinetic misalignment mechanism. The former case can naturally generate the observed baryon asymmetry for the Majoron mass <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mrow><e:msub><e:mrow><e:mi>m</e:mi></e:mrow><e:mrow><e:mi>J</e:mi></e:mrow></e:msub><e:mo>≳</e:mo><e:mi>TeV</e:mi></e:mrow></e:math> and the right-handed neutrino’s mass <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mrow><g:msub><g:mrow><g:mi>M</g:mi></g:mrow><g:mrow><g:mi>N</g:mi></g:mrow></g:msub><g:mo>≳</g:mo><g:msup><g:mrow><g:mn>10</g:mn></g:mrow><g:mrow><g:mn>11</g:mn></g:mrow></g:msup><g:mtext> </g:mtext><g:mtext> </g:mtext><g:mi>GeV</g:mi></g:mrow></g:math>. However, an additional decay channel of the Majoron is required to avoid the overclosure problem of the Majoron oscillation. The later scenario works successfully for <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:mrow><i:msub><i:mrow><i:mi>m</i:mi></i:mrow><i:mrow><i:mi>J</i:mi></i:mrow></i:msub><i:mo>≲</i:mo><i:mn>100</i:mn><i:mtext> </i:mtext><i:mtext> </i:mtext><i:mi>keV</i:mi></i:mrow></i:math> and <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:mrow><k:msub><k:mrow><k:mi>M</k:mi></k:mrow><k:mrow><k:mi>N</k:mi></k:mrow></k:msub><k:mo>≲</k:mo><k:msup><k:mrow><k:mn>10</k:mn></k:mrow><k:mrow><k:mn>9</k:mn></k:mrow></k:msup><k:mtext> </k:mtext><k:mtext> </k:mtext><k:mi>GeV</k:mi></k:mrow></k:math> while <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"><m:msub><m:mi>M</m:mi><m:mi>N</m:mi></m:msub></m:math> can be even far below the temperature of the electroweak phase transition as long as sufficiently large kinetic misalignment is provided. We also find that a sub-100 keV Majoron is a viable candidate for dark matter. Published by the American Physical Society 2024

Topics & Concepts