Highly boosted dielectron identification in proton-proton collisions at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> <mml:mo>=</mml:mo> <mml:mn>13</mml:mn> <mml:mtext> </mml:mtext> <mml:mtext> </mml:mtext> <mml:mi>TeV</mml:mi> </mml:math>

<jats:p> A new technique is developed to identify dielectrons ( <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mrow> <a:msup> <a:mi>e</a:mi> <a:mo>+</a:mo> </a:msup> <a:msup> <a:mi>e</a:mi> <a:mo>−</a:mo> </a:msup> </a:mrow> </a:math> ) with Lorentz boost <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:msub> <c:mi>γ</c:mi> <c:mi mathvariant="normal">L</c:mi> </c:msub> <c:mo>&gt;</c:mo> <c:mn>20</c:mn> </c:math> that produce one single merged cluster in the electromagnetic calorimeter of the CMS detector. The identification uses two multivariate models: one for the case where both electron tracks are reconstructed, and another where only one of the tracks is reconstructed. The efficiency is determined using proton-proton collision data collected at a center-of-mass energy of 13 TeV. Boosted <f:math xmlns:f="http://www.w3.org/1998/Math/MathML" display="inline"> <f:mi>J</f:mi> <f:mo>/</f:mo> <f:mi>ψ</f:mi> </f:math> mesons decaying into <h:math xmlns:h="http://www.w3.org/1998/Math/MathML" display="inline"> <h:mrow> <h:msup> <h:mrow> <h:mi>e</h:mi> </h:mrow> <h:mrow> <h:mo>+</h:mo> </h:mrow> </h:msup> <h:msup> <h:mrow> <h:mi>e</h:mi> </h:mrow> <h:mrow> <h:mo>−</h:mo> </h:mrow> </h:msup> </h:mrow> </h:math> pairs are used to estimate the efficiency of the model with two tracks, yielding an overall efficiency of 80%. The <j:math xmlns:j="http://www.w3.org/1998/Math/MathML" display="inline"> <j:mi>Z</j:mi> <j:mo stretchy="false">→</j:mo> <j:msup> <j:mi>μ</j:mi> <j:mo>+</j:mo> </j:msup> <j:msup> <j:mi>μ</j:mi> <j:mo>−</j:mo> </j:msup> <j:mi>γ</j:mi> </j:math> events, where the photon converts into a collimated dielectron, are used for the model with a single track, yielding an efficiency of about 60%. A dedicated energy correction for dielectron candidates is also developed using <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"> <m:msup> <m:mi>B</m:mi> <m:mo>±</m:mo> </m:msup> <m:mo stretchy="false">→</m:mo> <m:mrow> <m:mi>J</m:mi> <m:mo>/</m:mo> <m:mi>ψ</m:mi> </m:mrow> <m:msup> <m:mi>K</m:mi> <m:mo>±</m:mo> </m:msup> <m:mo stretchy="false">→</m:mo> <m:msup> <m:mi>e</m:mi> <m:mo>+</m:mo> </m:msup> <m:msup> <m:mi>e</m:mi> <m:mo>−</m:mo> </m:msup> <m:msup> <m:mi>K</m:mi> <m:mo>±</m:mo> </m:msup> </m:math> data. </jats:p>