Exclusion bounds for neutral gauge bosons

We study how the recent experimental results constrain the gauge sectors of <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> extensions of the standard model using a novel representation of the parameter space. We determine the bounds on the mixing angle between the massive gauge bosons or, equivalently, the new gauge coupling as a function of the mass <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:msub><e:mi>M</e:mi><e:msup><e:mi>Z</e:mi><e:mo>′</e:mo></e:msup></e:msub></e:math> of the new neutral gauge boson <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:msup><g:mi>Z</g:mi><g:mo>′</g:mo></g:msup></g:math> in the approximate range <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:mrow><i:mo stretchy="false">(</i:mo><i:msup><i:mrow><i:mn>10</i:mn></i:mrow><i:mrow><i:mo>−</i:mo><i:mn>2</i:mn></i:mrow></i:msup><i:mo>,</i:mo><i:msup><i:mrow><i:mn>10</i:mn></i:mrow><i:mrow><i:mn>4</i:mn></i:mrow></i:msup><i:mo stretchy="false">)</i:mo><i:mtext> </i:mtext><i:mtext> </i:mtext><i:mi>GeV</i:mi><i:mo>/</i:mo><i:msup><i:mrow><i:mi>c</i:mi></i:mrow><i:mrow><i:mn>2</i:mn></i:mrow></i:msup></i:mrow></i:math>. We consider the most stringent bounds obtained from direct searches for the <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"><m:msup><m:mi>Z</m:mi><m:mo>′</m:mo></m:msup></m:math>. We also exhibit the allowed parameter space by comparing the predicted and measured values of the <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"><o:mi>ρ</o:mi></o:math> parameter and those of the mass of the <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" display="inline"><q:mi>W</q:mi></q:math> boson. Finally, we discuss the prospects of <s:math xmlns:s="http://www.w3.org/1998/Math/MathML" display="inline"><s:msup><s:mi>Z</s:mi><s:mo>′</s:mo></s:msup></s:math> searches at future colliders.