95 GeV Higgs boson and spontaneous <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>C</mml:mi><mml:mi>P</mml:mi></mml:mrow></mml:math>-violation at the finite temperature

The ATLAS and CMS collaborations reported a diphoton excess in the invariant mass distribution around the 95.4 GeV with a local significance of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mn>3.1</a:mn><a:mi>σ</a:mi></a:math>. Moreover, there is another <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mn>2.3</c:mn><c:mi>σ</c:mi></c:math> local excess in the <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mi>b</e:mi><e:mover accent="true"><e:mi>b</e:mi><e:mo stretchy="false">¯</e:mo></e:mover></e:math> final state at large electron-positron collider in the same mass region. A plausible solution is that the Higgs sector is extended to include an additional Higgs boson with a mass of 95.4 GeV. We study a complex singlet scalar extension of the two-Higgs-doublet model in which the 95.4 GeV Higgs is from the mixing of three <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:mi>C</i:mi><i:mi>P</i:mi></i:math>-even Higgs fields. In addition, the extended Higgs potential can achieve spontaneous <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:mi>C</k:mi><k:mi>P</k:mi></k:math>-violation at the finite temperature and restore <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"><m:mi>C</m:mi><m:mi>P</m:mi></m:math> symmetry at the present temperature of the Universe. We find that the model can simultaneously explain the baryon asymmetry of the Universe, the diphoton and <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"><o:mi>b</o:mi><o:mover accent="true"><o:mi>b</o:mi><o:mo stretchy="false">¯</o:mo></o:mover></o:math> excesses around the 95.4 GeV while satisfying various relevant constraints including the experiments of collider and electric dipole moment. Published by the American Physical Society 2024