LHC signals for a 2HDM with Z ′ in a neutrinophilic U ( 1 ) model

We consider a neutrinophilic <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mi>U</a:mi> <a:mo stretchy="false">(</a:mo> <a:mn>1</a:mn> <a:mo stretchy="false">)</a:mo> </a:math> extension of the Standard Model (SM) under which only a second Higgs doublet and SM singlet scalars and fermions are charged. The new gauge boson <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:msup> <e:mi>Z</e:mi> <e:mo>′</e:mo> </e:msup> </e:math> couples to the SM minimally, generated by <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"> <g:mi>Z</g:mi> <g:mo>−</g:mo> <g:msup> <g:mi>Z</g:mi> <g:mo>′</g:mo> </g:msup> </g:math> mixing. As the <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"> <i:msup> <i:mi>Z</i:mi> <i:mo>′</i:mo> </i:msup> </i:math> is very weakly coupled, it can mostly be produced through the decay of the scalars from the second Higgs doublet at the Large Hadron Collider (LHC). We discuss the scalar sector of the model in detail and consider decay modes such as <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"> <k:mo stretchy="false">(</k:mo> <k:msup> <k:mi>H</k:mi> <k:mo>±</k:mo> </k:msup> <k:mo stretchy="false">→</k:mo> <k:msup> <k:mi>W</k:mi> <k:mo>±</k:mo> </k:msup> <k:msup> <k:mi>Z</k:mi> <k:mo>′</k:mo> </k:msup> <k:mo>,</k:mo> <k:msub> <k:mi>h</k:mi> <k:mn>2</k:mn> </k:msub> <k:mo stretchy="false">→</k:mo> <k:mi>V</k:mi> <k:mi>V</k:mi> <k:mo>,</k:mo> <k:mo stretchy="false">(</k:mo> <k:mi>V</k:mi> <k:mo>=</k:mo> <k:msup> <k:mi>W</k:mi> <k:mo>±</k:mo> </k:msup> <k:mo>,</k:mo> <k:mi>Z</k:mi> <k:mo>,</k:mo> <k:msup> <k:mi>Z</k:mi> <k:mo>′</k:mo> </k:msup> <k:mo stretchy="false">)</k:mo> <k:mo>,</k:mo> <k:msub> <k:mi>A</k:mi> <k:mn>2</k:mn> </k:msub> <k:mo stretchy="false">→</k:mo> <k:msub> <k:mi>h</k:mi> <k:mn>1</k:mn> </k:msub> <k:msup> <k:mi>Z</k:mi> <k:mo>′</k:mo> </k:msup> <k:mo stretchy="false">(</k:mo> <k:mi>Z</k:mi> <k:mo stretchy="false">)</k:mo> <k:mo stretchy="false">)</k:mo> </k:math> that lead to multilepton signals at the LHC from the pair production of the scalars. We analyze the signal with a representative value of the <v:math xmlns:v="http://www.w3.org/1998/Math/MathML" display="inline"> <v:msup> <v:mi>Z</v:mi> <v:mo>′</v:mo> </v:msup> </v:math> mass to show the discovery potential of the two-Higgs doublet model scalars at the LHC.