Observation of the Ω ( 2012 ) baryon at the LHC

A signal consistent with the <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mi mathvariant="normal">Ω</a:mi> <a:mo stretchy="false">(</a:mo> <a:mn>2012</a:mn> <a:mo stretchy="false">)</a:mo> </a:math> baryon has been observed with a significance of <f:math xmlns:f="http://www.w3.org/1998/Math/MathML" display="inline"> <f:mn>15</f:mn> <f:mi>σ</f:mi> </f:math> in pp collisions at <h:math xmlns:h="http://www.w3.org/1998/Math/MathML" display="inline"> <h:mrow> <h:msqrt> <h:mrow> <h:mi>s</h:mi> </h:mrow> </h:msqrt> <h:mo>=</h:mo> <h:mn>13</h:mn> <h:mtext> </h:mtext> <h:mtext> </h:mtext> <h:mi>TeV</h:mi> </h:mrow> </h:math> at the LHC. In this paper, the analysis technique is described and measurements of the mass and width of the <j:math xmlns:j="http://www.w3.org/1998/Math/MathML" display="inline"> <j:mi mathvariant="normal">Ω</j:mi> <j:mo stretchy="false">(</j:mo> <j:mn>2012</j:mn> <j:mo stretchy="false">)</j:mo> </j:math> are reported, along with the first measurement of its transverse-momentum spectrum and yield. This paper corroborates the observation by the Belle Collaboration of this excited <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"> <o:mi mathvariant="normal">Ω</o:mi> </o:math> state and the observation that the <r:math xmlns:r="http://www.w3.org/1998/Math/MathML" display="inline"> <r:mi mathvariant="normal">Ω</r:mi> <r:mo stretchy="false">(</r:mo> <r:mn>2012</r:mn> <r:mo stretchy="false">)</r:mo> </r:math> has a rather narrow width for a strongly decaying resonance. The yield measurement is combined with a statistical thermal model calculation of strange baryon yield ratios to obtain estimates of the <w:math xmlns:w="http://www.w3.org/1998/Math/MathML" display="inline"> <w:mrow> <w:mi mathvariant="normal">Ω</w:mi> <w:mo stretchy="false">(</w:mo> <w:mn>2012</w:mn> <w:msup> <w:mo stretchy="false">)</w:mo> <w:mo>−</w:mo> </w:msup> </w:mrow> <w:mo stretchy="false">→</w:mo> <w:mi mathvariant="normal">Ξ</w:mi> <w:mover accent="true"> <w:mi mathvariant="normal">K</w:mi> <w:mo stretchy="false">¯</w:mo> </w:mover> </w:math> branching ratios. These results will improve our understanding of the internal structure and mass spectrum of excited baryon states and serve as a baseline for searches regarding modifications of these properties in high-temperature media.