Probing charged Higgs bosons in the two-Higgs-doublet model type II with vectorlike quarks

Abstract

We study the phenomenology of charged Higgs bosons (<a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msup><a:mi>H</a:mi><a:mo>±</a:mo></a:msup></a:math>) and vectorlike quarks (VLQs), denoted as <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>T</c:mi></c:math>, the latter possessing a charge identical to the top quark one, within the framework of the two-Higgs-doublet model type II (2HDM-II). Upon examining two scenarios, one featuring a singlet (<e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mi>T</e:mi></e:math>) [<g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mrow><g:mn>2</g:mn><g:mi>HDM</g:mi><g:mtext>−</g:mtext><g:mi>II</g:mi><g:mo>+</g:mo><g:mo stretchy="false">(</g:mo><g:mi>T</g:mi><g:mo stretchy="false">)</g:mo></g:mrow></g:math>] and another a doublet <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:mo stretchy="false">(</k:mo><k:mi>T</k:mi><k:mi>B</k:mi><k:mo stretchy="false">)</k:mo></k:math> [<o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"><o:mrow><o:mn>2</o:mn><o:mi>HDM</o:mi><o:mtext>−</o:mtext><o:mi>II</o:mi><o:mo>+</o:mo><o:mo stretchy="false">(</o:mo><o:mi>T</o:mi><o:mi>B</o:mi><o:mo stretchy="false">)</o:mo></o:mrow></o:math>], we discover that the presence of VLQs has a significant effect on the (pseudo)scalar sector of the 2HDM-II. In particular, this leads to a reduction in the strict constraint on the mass of the charged Higgs boson, which is imposed by <s:math xmlns:s="http://www.w3.org/1998/Math/MathML" display="inline"><s:mi>B</s:mi></s:math>-physics observables, specifically <u:math xmlns:u="http://www.w3.org/1998/Math/MathML" display="inline"><u:mi>B</u:mi><u:mo stretchy="false">→</u:mo><u:msub><u:mi>X</u:mi><u:mi>s</u:mi></u:msub><u:mi>γ</u:mi></u:math>. The observed reduction stems from modifications in the charged Higgs couplings to the Standard Model top and bottom quarks. Notably, the degree of this reduction varies distinctly between the singlet 2HDM+(<x:math xmlns:x="http://www.w3.org/1998/Math/MathML" display="inline"><x:mi>T</x:mi></x:math>) and doublet <z:math xmlns:z="http://www.w3.org/1998/Math/MathML" display="inline"><z:mrow><z:mn>2</z:mn><z:mi>HDM</z:mi><z:mo>+</z:mo><z:mo stretchy="false">(</z:mo><z:mi>T</z:mi><z:mi>B</z:mi><z:mo stretchy="false">)</z:mo></z:mrow></z:math> scenarios. Additionally, our investigation extends to constraints imposed by the oblique parameters <db:math xmlns:db="http://www.w3.org/1998/Math/MathML" display="inline"><db:mi>S</db:mi></db:math> and <fb:math xmlns:fb="http://www.w3.org/1998/Math/MathML" display="inline"><fb:mi>T</fb:mi></fb:math> on the VLQ mixing angles. Furthermore, to facilitate efficient exploration of the “<hb:math xmlns:hb="http://www.w3.org/1998/Math/MathML" display="inline"><hb:mrow><hb:mn>2</hb:mn><hb:mi>HDM</hb:mi><hb:mtext>−</hb:mtext><hb:mi>II</hb:mi><hb:mo>+</hb:mo><hb:mi>VLQ</hb:mi></hb:mrow></hb:math>” parameter space, we present results on pair production of VLQs <jb:math xmlns:jb="http://www.w3.org/1998/Math/MathML" display="inline"><jb:mi>T</jb:mi></jb:math> (<lb:math xmlns:lb="http://www.w3.org/1998/Math/MathML" display="inline"><lb:mi>p</lb:mi><lb:mi>p</lb:mi><lb:mo stretchy="false">→</lb:mo><lb:mi>T</lb:mi><lb:mover accent="true"><lb:mi>T</lb:mi><lb:mo stretchy="false">¯</lb:mo></lb:mover></lb:math>), followed by <qb:math xmlns:qb="http://www.w3.org/1998/Math/MathML" display="inline"><qb:mi>T</qb:mi><qb:mo stretchy="false">→</qb:mo><qb:msup><qb:mi>H</qb:mi><qb:mo>±</qb:mo></qb:msup><qb:mi>b</qb:mi></qb:math> and <tb:math xmlns:tb="http://www.w3.org/1998/Math/MathML" display="inline"><tb:msup><tb:mi>H</tb:mi><tb:mo>±</tb:mo></tb:msup><tb:mo stretchy="false">→</tb:mo><tb:mi>t</tb:mi><tb:mi>b</tb:mi></tb:math> decays, yielding a distinctive <wb:math xmlns:wb="http://www.w3.org/1998/Math/MathML" display="inline"><wb:mn>2</wb:mn><wb:mi>t</wb:mi><wb:mn>4</wb:mn><wb:mi>b</wb:mi></wb:math> final state. This investigation thus provides valuable insights guiding the search for extended Higgs and quark sectors at the Large Hadron Collider (LHC) at CERN. Published by the American Physical Society 2024

Topics & Concepts