Abstract:
The production of prompt <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msubsup><a:mi>D</a:mi><a:mi>s</a:mi><a:mo>+</a:mo></a:msubsup></a:math> and <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:msup><c:mi>D</c:mi><c:mo>+</c:mo></c:msup></c:math> mesons is measured by the LHCb experiment in proton-lead (<e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mrow><e:mi>p</e:mi><e:mi>Pb</e:mi></e:mrow></e:math>) collisions in both the forward (<g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mn>1.5</g:mn><g:mo><</g:mo><g:msup><g:mi>y</g:mi><g:mo>*</g:mo></g:msup><g:mo><</g:mo><g:mn>4.0</g:mn></g:math>) and backward (<i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:mo>−</i:mo><i:mn>5.0</i:mn><i:mo><</i:mo><i:msup><i:mi>y</i:mi><i:mo>*</i:mo></i:msup><i:mo><</i:mo><i:mo>−</i:mo><i:mn>2.5</i:mn></i:math>) rapidity regions at a nucleon-nucleon center-of-mass energy of <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:mrow><k:mrow><k:msqrt><k:mrow><k:msub><k:mrow><k:mi>s</k:mi></k:mrow><k:mrow><k:mi>NN</k:mi></k:mrow></k:msub></k:mrow></k:msqrt></k:mrow><k:mo>=</k:mo><k:mn>8.16</k:mn><k:mtext> </k:mtext><k:mtext> </k:mtext><k:mi>TeV</k:mi></k:mrow></k:math>. The nuclear modification factors of both <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"><m:msubsup><m:mi>D</m:mi><m:mi>s</m:mi><m:mo>+</m:mo></m:msubsup></m:math> and <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"><o:msup><o:mi>D</o:mi><o:mo>+</o:mo></o:msup></o:math> mesons are determined as a function of transverse momentum, <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" display="inline"><q:msub><q:mi>p</q:mi><q:mi mathvariant="normal">T</q:mi></q:msub></q:math>, and rapidity. In addition, the <t:math xmlns:t="http://www.w3.org/1998/Math/MathML" display="inline"><t:msubsup><t:mi>D</t:mi><t:mi>s</t:mi><t:mo>+</t:mo></t:msubsup></t:math> to <v:math xmlns:v="http://www.w3.org/1998/Math/MathML" display="inline"><v:msup><v:mi>D</v:mi><v:mo>+</v:mo></v:msup></v:math> cross section ratio is measured as a function of the primary charged particle multiplicity in the event. An enhanced <x:math xmlns:x="http://www.w3.org/1998/Math/MathML" display="inline"><x:msubsup><x:mi>D</x:mi><x:mi>s</x:mi><x:mo>+</x:mo></x:msubsup></x:math> to <z:math xmlns:z="http://www.w3.org/1998/Math/MathML" display="inline"><z:msup><z:mi>D</z:mi><z:mo>+</z:mo></z:msup></z:math> production in high-multiplicity events is observed for the whole measured <bb:math xmlns:bb="http://www.w3.org/1998/Math/MathML" display="inline"><bb:msub><bb:mi>p</bb:mi><bb:mi mathvariant="normal">T</bb:mi></bb:msub></bb:math> range, in particular at low <eb:math xmlns:eb="http://www.w3.org/1998/Math/MathML" display="inline"><eb:msub><eb:mi>p</eb:mi><eb:mi mathvariant="normal">T</eb:mi></eb:msub></eb:math> and backward rapidity, where the significance exceeds six standard deviations. This constitutes the first observation of strangeness enhancement in charm quark hadronization in high-multiplicity <hb:math xmlns:hb="http://www.w3.org/1998/Math/MathML" display="inline"><hb:mrow><hb:mi>p</hb:mi><hb:mi>Pb</hb:mi></hb:mrow></hb:math> collisions. The results are also qualitatively consistent with the presence of quark coalescence as an additional charm quark hadronization mechanism in high-multiplicity proton-lead collisions. © 2024 CERN, for the LHCb Collaboration 2024 CERN
Tópico:
High-Energy Particle Collisions Research
