Accumulating hints for flavor-violating Higgs bosons at the electroweak scale

We show that supplementing the Standard Model by only a second Higgs doublet, a combined explanation of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>h</a:mi><a:mo stretchy="false">→</a:mo><a:mi>e</a:mi><a:mi>τ</a:mi></a:math>, <d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline"><d:mi>h</d:mi><d:mo stretchy="false">→</d:mo><d:mi>μ</d:mi><d:mi>τ</d:mi></d:math>, <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mi>b</g:mi><g:mo stretchy="false">→</g:mo><g:mi>s</g:mi><g:msup><g:mo>ℓ</g:mo><g:mo>+</g:mo></g:msup><g:msup><g:mo>ℓ</g:mo><g:mo>−</g:mo></g:msup></g:math>, the <j:math xmlns:j="http://www.w3.org/1998/Math/MathML" display="inline"><j:mi>W</j:mi></j:math> mass and <l:math xmlns:l="http://www.w3.org/1998/Math/MathML" display="inline"><l:mi>R</l:mi><l:mo stretchy="false">(</l:mo><l:msup><l:mi>D</l:mi><l:mrow><l:mo stretchy="false">(</l:mo><l:mo>*</l:mo><l:mo stretchy="false">)</l:mo></l:mrow></l:msup><l:mo stretchy="false">)</l:mo></l:math> as well as the excess in <r:math xmlns:r="http://www.w3.org/1998/Math/MathML" display="inline"><r:mi>t</r:mi><r:mo stretchy="false">→</r:mo><r:mi>b</r:mi><r:msup><r:mi>H</r:mi><r:mo>+</r:mo></r:msup><r:mo stretchy="false">(</r:mo><r:mn>130</r:mn><r:mtext> </r:mtext><r:mtext> </r:mtext><r:mi>GeV</r:mi><r:mo stretchy="false">)</r:mo><r:mo stretchy="false">→</r:mo><r:mi>b</r:mi><r:mover accent="true"><r:mi>b</r:mi><r:mo stretchy="false">¯</r:mo></r:mover><r:mi>c</r:mi></r:math> is possible. While this requires flavor violating couplings, the stringent bounds from, e.g., <z:math xmlns:z="http://www.w3.org/1998/Math/MathML" display="inline"><z:mi>μ</z:mi><z:mo stretchy="false">→</z:mo><z:mi>e</z:mi><z:mi>γ</z:mi></z:math>, <cb:math xmlns:cb="http://www.w3.org/1998/Math/MathML" display="inline"><cb:mi>τ</cb:mi><cb:mo stretchy="false">→</cb:mo><cb:mi>μ</cb:mi><cb:mi>γ</cb:mi></cb:math>, <fb:math xmlns:fb="http://www.w3.org/1998/Math/MathML" display="inline"><fb:msub><fb:mi>B</fb:mi><fb:mi>s</fb:mi></fb:msub><fb:mo>−</fb:mo><fb:msub><fb:mover accent="true"><fb:mi>B</fb:mi><fb:mo stretchy="false">¯</fb:mo></fb:mover><fb:mi>s</fb:mi></fb:msub></fb:math> mixing, <jb:math xmlns:jb="http://www.w3.org/1998/Math/MathML" display="inline"><jb:mi>b</jb:mi><jb:mo stretchy="false">→</jb:mo><jb:mi>s</jb:mi><jb:mi>γ</jb:mi></jb:math>, low mass dijet, and <mb:math xmlns:mb="http://www.w3.org/1998/Math/MathML" display="inline"><mb:mi>p</mb:mi><mb:mi>p</mb:mi><mb:mo stretchy="false">→</mb:mo><mb:msup><mb:mi>H</mb:mi><mb:mo>+</mb:mo></mb:msup><mb:msup><mb:mi>H</mb:mi><mb:mo>−</mb:mo></mb:msup><mb:mo stretchy="false">→</mb:mo><mb:msup><mb:mi>τ</mb:mi><mb:mo>+</mb:mo></mb:msup><mb:msup><mb:mi>τ</mb:mi><mb:mo>−</mb:mo></mb:msup><mb:mi>ν</mb:mi><mb:mover accent="true"><mb:mi>ν</mb:mi><mb:mo stretchy="false">¯</mb:mo></mb:mover></mb:math> searches can be avoided. However, the model is very constrained; it inevitably predicts a shift in the SM Higgs coupling strength to tau leptons as well as a nonzero <sb:math xmlns:sb="http://www.w3.org/1998/Math/MathML" display="inline"><sb:mi>t</sb:mi><sb:mo stretchy="false">→</sb:mo><sb:mi>h</sb:mi><sb:mi>c</sb:mi></sb:math> rate, as indeed preferred by recent measurements. We study three benchmark points providing such a simultaneous explanation and calculate their predictions, including collider signatures which can be tested with upcoming LHC run-3 data. Published by the American Physical Society 2024