Exclusive dielectron production in ultraperipheral Pb+Pb collisions at $$ \sqrt{s_{\textrm{NN}}} $$ = 5.02 TeV with ATLAS



Aad, G, Abbott, B, Abbott, DC, Abeling, K, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC
et al (show 2905 more authors) (2023) Exclusive dielectron production in ultraperipheral Pb+Pb collisions at $$ \sqrt{s_{\textrm{NN}}} $$ = 5.02 TeV with ATLAS. Journal of High Energy Physics, 2023 (6). 182-.

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Abstract

<jats:title>A<jats:sc>bstract</jats:sc> </jats:title><jats:p>Exclusive production of dielectron pairs, <jats:italic>γγ</jats:italic> → <jats:italic>e</jats:italic><jats:sup>+</jats:sup><jats:italic>e</jats:italic><jats:sup><jats:italic>−</jats:italic></jats:sup>, is studied using <jats:inline-formula><jats:alternatives><jats:tex-math>$$ {\mathcal{L}}_{\textrm{int}} $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>L</mml:mi> <mml:mi>int</mml:mi> </mml:msub> </mml:math></jats:alternatives></jats:inline-formula> = 1<jats:italic>.</jats:italic>72 nb<jats:sup><jats:italic>−</jats:italic>1</jats:sup> of data from ultraperipheral collisions of lead nuclei at <jats:inline-formula><jats:alternatives><jats:tex-math>$$ \sqrt{s_{\textrm{NN}}} $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:msub> <mml:mi>s</mml:mi> <mml:mi>NN</mml:mi> </mml:msub> </mml:msqrt> </mml:math></jats:alternatives></jats:inline-formula> = 5<jats:italic>.</jats:italic>02 TeV recorded by the ATLAS detector at the LHC. The process of interest proceeds via photon–photon interactions in the strong electromagnetic fields of relativistic lead nuclei. Dielectron production is measured in the fiducial region defined by following requirements: electron transverse momentum <jats:inline-formula><jats:alternatives><jats:tex-math>$$ {p}_{\textrm{T}}^e $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>p</mml:mi> <mml:mi>T</mml:mi> <mml:mi>e</mml:mi> </mml:msubsup> </mml:math></jats:alternatives></jats:inline-formula><jats:italic>&gt;</jats:italic> 2<jats:italic>.</jats:italic>5 GeV, absolute electron pseudorapidity <jats:italic>|η</jats:italic><jats:sup><jats:italic>e</jats:italic></jats:sup><jats:italic>| &lt;</jats:italic> 2<jats:italic>.</jats:italic>5, dielectron invariant mass <jats:italic>m</jats:italic><jats:sub><jats:italic>ee</jats:italic></jats:sub><jats:italic>&gt;</jats:italic> 5 GeV, and dielectron transverse momentum <jats:inline-formula><jats:alternatives><jats:tex-math>$$ {p}_{\textrm{T}}^{ee} $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>p</mml:mi> <mml:mi>T</mml:mi> <mml:mi>ee</mml:mi> </mml:msubsup> </mml:math></jats:alternatives></jats:inline-formula><jats:italic>&lt;</jats:italic> 2 GeV. Differential cross-sections are measured as a function of <jats:italic>m</jats:italic><jats:sub><jats:italic>ee</jats:italic></jats:sub>, average <jats:inline-formula><jats:alternatives><jats:tex-math>$$ {p}_{\textrm{T}}^e $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>p</mml:mi> <mml:mi>T</mml:mi> <mml:mi>e</mml:mi> </mml:msubsup> </mml:math></jats:alternatives></jats:inline-formula>, absolute dielectron rapidity |<jats:italic>y</jats:italic><jats:sub><jats:italic>ee</jats:italic></jats:sub>|, and scattering angle in the dielectron rest frame, |cos <jats:italic>θ</jats:italic><jats:sup>*</jats:sup>|, in the inclusive sample, and also with a requirement of no activity in the forward direction. The total integrated fiducial cross-section is measured to be <jats:inline-formula><jats:alternatives><jats:tex-math>$$ 215\pm 1{\left(\textrm{stat}.\right)}_{-20}^{+23}\left(\textrm{syst}.\right)\pm 4\left(\textrm{lumi}.\right) $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mn>215</mml:mn> <mml:mo>±</mml:mo> <mml:mn>1</mml:mn> <mml:msubsup> <mml:mfenced> <mml:mrow> <mml:mtext>stat</mml:mtext> <mml:mo>.</mml:mo> </mml:mrow> </mml:mfenced> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>20</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>23</mml:mn> </mml:mrow> </mml:msubsup> <mml:mfenced> <mml:mrow> <mml:mtext>syst</mml:mtext> <mml:mo>.</mml:mo> </mml:mrow> </mml:mfenced> <mml:mo>±</mml:mo> <mml:mn>4</mml:mn> <mml:mfenced> <mml:mrow> <mml:mtext>lumi</mml:mtext> <mml:mo>.</mml:mo> </mml:mrow> </mml:mfenced> </mml:math></jats:alternatives></jats:inline-formula><jats:italic>μ</jats:italic>b. Within experimental uncertainties the measured integrated cross-section is in good agreement with the QED predictions from the Monte Carlo programs S<jats:sc>tarlight</jats:sc> and S<jats:sc>uper</jats:sc>C<jats:sc>hic</jats:sc>, confirming the broad features of the initial photon fluxes. The differential cross-sections show systematic differences from these predictions which are more pronounced at high <jats:italic>|y</jats:italic><jats:sub><jats:italic>ee</jats:italic></jats:sub><jats:italic>|</jats:italic> and <jats:italic>|</jats:italic>cos <jats:italic>θ</jats:italic><jats:sup>*</jats:sup><jats:italic>|</jats:italic> values.</jats:p>

Item Type: Article
Divisions: Faculty of Science and Engineering > School of Physical Sciences
Depositing User: Symplectic Admin
Date Deposited: 09 Aug 2023 10:19
Last Modified: 18 Mar 2024 03:57
DOI: 10.1007/jhep06(2023)182
Open Access URL: https://link.springer.com/article/10.1007/JHEP06(2...
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3172108