Searching for charged Higgs bosons via <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>e</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:msup><mml:mi>e</mml:mi><mml:mo>−</mml:mo></mml:msup><mml:mo stretchy="false">→</mml:mo><mml:msup><mml:mi>H</mml:mi><mml:mo>±</mml:mo></mml:msup><mml:msup><mml:mi>W</mml:mi><mml:mo>∓</mml:mo></mml:msup><mml:mi>S</mml:mi></mml:math> at the ILC

Abstract

We investigate the phenomenology of the charged Higgs boson at the International Linear Collider (ILC) within the framework of the type-X Two-Higgs Doublet Model, where a light charged Higgs boson, with a mass around 200 GeV or even smaller than top quark mass, is still being consistent with flavor physics data as well as with collider experimental data. In the theoretically and experimentally allowed parameter space, the <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msup><a:mi>e</a:mi><a:mo>+</a:mo></a:msup><a:msup><a:mi>e</a:mi><a:mo>−</a:mo></a:msup><a:mo stretchy="false">→</a:mo><a:msup><a:mi>H</a:mi><a:mo>±</a:mo></a:msup><a:msup><a:mi>W</a:mi><a:mo>∓</a:mo></a:msup><a:mi>S</a:mi></a:math> (with <d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline"><d:mrow><d:mi>S</d:mi><d:mo>=</d:mo><d:mi>H</d:mi></d:mrow></d:math>, <f:math xmlns:f="http://www.w3.org/1998/Math/MathML" display="inline"><f:mrow><f:mi>A</f:mi></f:mrow></f:math>) production processes can yield signatures with event rates larger than those from <h:math xmlns:h="http://www.w3.org/1998/Math/MathML" display="inline"><h:msup><h:mi>e</h:mi><h:mo>+</h:mo></h:msup><h:msup><h:mi>e</h:mi><h:mo>−</h:mo></h:msup><h:mo stretchy="false">→</h:mo><h:msup><h:mi>H</h:mi><h:mo>+</h:mo></h:msup><h:msup><h:mi>H</h:mi><h:mo>−</h:mo></h:msup></h:math> and offer sensitivity to the Higgs mixing parameter <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:mi>sin</k:mi><k:mo stretchy="false">(</k:mo><k:mi>β</k:mi><k:mo>−</k:mo><k:mi>α</k:mi><k:mo stretchy="false">)</k:mo></k:math>. We consider the bosonic <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"><o:msup><o:mi>H</o:mi><o:mo>±</o:mo></o:msup><o:mo stretchy="false">→</o:mo><o:msup><o:mi>W</o:mi><o:mo>±</o:mo></o:msup><o:mi>S</o:mi></o:math> decays, where the neutral scalar <r:math xmlns:r="http://www.w3.org/1998/Math/MathML" display="inline"><r:mi>S</r:mi></r:math> further decays into a pair of tau leptons. We show, through a detector-level Monte Carlo analysis, that the resulting <t:math xmlns:t="http://www.w3.org/1998/Math/MathML" display="inline"><t:mo stretchy="false">[</t:mo><t:mi>τ</t:mi><t:mi>τ</t:mi><t:mo stretchy="false">]</t:mo><t:mo stretchy="false">[</t:mo><t:mi>τ</t:mi><t:mi>τ</t:mi><t:mo stretchy="false">]</t:mo><t:mi>W</t:mi><t:mi>W</t:mi></t:math> final state could be seen at the ILC with at least 500 GeV center-of-mass energy and <z:math xmlns:z="http://www.w3.org/1998/Math/MathML" display="inline"><z:mn>500</z:mn><z:mtext> </z:mtext><z:mtext> </z:mtext><z:msup><z:mi>fb</z:mi><z:mrow><z:mo>−</z:mo><z:mn>1</z:mn></z:mrow></z:msup></z:math> of luminosity.