Observation of the ϒ(3S) Meson and Suppression of ϒ States in Pb-Pb Collisions at sNN=5.02 TeV

Abstract

The production of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mi mathvariant="normal">ϒ</a:mi><a:mrow><a:mo stretchy="false">(</a:mo><a:mn>2</a:mn><a:mi>S</a:mi><a:mo stretchy="false">)</a:mo></a:mrow></a:mrow></a:math> and <f:math xmlns:f="http://www.w3.org/1998/Math/MathML" display="inline"><f:mi mathvariant="normal">ϒ</f:mi><f:mrow><f:mo stretchy="false">(</f:mo><f:mn>3</f:mn><f:mi>S</f:mi><f:mo stretchy="false">)</f:mo></f:mrow></f:math> mesons in lead-lead (Pb-Pb) and proton-proton (<k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:mi>p</k:mi><k:mi>p</k:mi></k:math>) collisions is studied in their dimuon decay channel using the CMS detector at the LHC. The <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"><m:mi mathvariant="normal">ϒ</m:mi><m:mrow><m:mo stretchy="false">(</m:mo><m:mn>3</m:mn><m:mi>S</m:mi><m:mo stretchy="false">)</m:mo></m:mrow></m:math> meson is observed for the first time in Pb-Pb collisions, with a significance above 5 standard deviations. The ratios of yields measured in Pb-Pb and <r:math xmlns:r="http://www.w3.org/1998/Math/MathML" display="inline"><r:mi>p</r:mi><r:mi>p</r:mi></r:math> collisions are reported for both the <t:math xmlns:t="http://www.w3.org/1998/Math/MathML" display="inline"><t:mi mathvariant="normal">ϒ</t:mi><t:mrow><t:mo stretchy="false">(</t:mo><t:mn>2</t:mn><t:mi>S</t:mi><t:mo stretchy="false">)</t:mo></t:mrow></t:math> and <y:math xmlns:y="http://www.w3.org/1998/Math/MathML" display="inline"><y:mi mathvariant="normal">ϒ</y:mi><y:mrow><y:mo stretchy="false">(</y:mo><y:mn>3</y:mn><y:mi>S</y:mi><y:mo stretchy="false">)</y:mo></y:mrow></y:math> mesons, as functions of transverse momentum and Pb-Pb collision centrality. These ratios, when appropriately scaled, are significantly less than unity, indicating a suppression of <db:math xmlns:db="http://www.w3.org/1998/Math/MathML" display="inline"><db:mi mathvariant="normal">ϒ</db:mi></db:math> yields in Pb-Pb collisions. This suppression increases from peripheral to central Pb-Pb collisions. Furthermore, the suppression is stronger for <gb:math xmlns:gb="http://www.w3.org/1998/Math/MathML" display="inline"><gb:mi mathvariant="normal">ϒ</gb:mi><gb:mrow><gb:mo stretchy="false">(</gb:mo><gb:mn>3</gb:mn><gb:mi>S</gb:mi><gb:mo stretchy="false">)</gb:mo></gb:mrow></gb:math> mesons compared to <lb:math xmlns:lb="http://www.w3.org/1998/Math/MathML" display="inline"><lb:mi mathvariant="normal">ϒ</lb:mi><lb:mrow><lb:mo stretchy="false">(</lb:mo><lb:mn>2</lb:mn><lb:mi>S</lb:mi><lb:mo stretchy="false">)</lb:mo></lb:mrow></lb:math> mesons, extending the pattern of sequential suppression of quarkonium states in nuclear collisions previously seen for the <qb:math xmlns:qb="http://www.w3.org/1998/Math/MathML" display="inline"><qb:mi>J</qb:mi><qb:mo>/</qb:mo><qb:mi>ψ</qb:mi></qb:math>, <sb:math xmlns:sb="http://www.w3.org/1998/Math/MathML" display="inline"><sb:mrow><sb:mi>ψ</sb:mi><sb:mo stretchy="false">(</sb:mo><sb:mn>2</sb:mn><sb:mi>S</sb:mi><sb:mo stretchy="false">)</sb:mo></sb:mrow></sb:math>, <wb:math xmlns:wb="http://www.w3.org/1998/Math/MathML" display="inline"><wb:mi mathvariant="normal">ϒ</wb:mi><wb:mrow><wb:mo stretchy="false">(</wb:mo><wb:mn>1</wb:mn><wb:mi>S</wb:mi><wb:mo stretchy="false">)</wb:mo></wb:mrow></wb:math>, and <bc:math xmlns:bc="http://www.w3.org/1998/Math/MathML" display="inline"><bc:mi mathvariant="normal">ϒ</bc:mi><bc:mrow><bc:mo stretchy="false">(</bc:mo><bc:mn>2</bc:mn><bc:mi>S</bc:mi><bc:mo stretchy="false">)</bc:mo></bc:mrow></bc:math> mesons. © 2024 CERN, for the CMS Collaboration 2024 CERN