Measurement of the production of a $W$ boson in association with a charmed hadron in $pp$ collisions at $\sqrt{s}$ = $\mathrm{13 TeV}$ with the ATLAS detector

• Published in: Physical review. D 2023-08, Vol.108 (3)
• Main Authors: Adorni, S, Afik, Y, Agaras, MN, Ahmad, A, Ahuja, S, Ai, X, Alderweireldt, S, Ali, S, Aliev, M, Alpigiani, C, Ambler, A, Ames, CG, Dos Santos, SP Amor, Annovi, A, Anulli, F, Aoki, M, Aparo, MA, Bella, L Aperio, Ferraz, V Araujo, Arling, J-H, Assahsah, J, Atmani, H, Azuelos, G, Backman, F, Ballabene, E, Banas, E, Baron, P, Barone, G, Barreiro, F, Barsov, S, Bartels, F, Bartoldus, R, Barton, AE, Basso, MJ, Batool, B, Bee, CP, Beirer, JF, Belfkir, M, Benhammou, Y, Benoit, M, Bentvelsen, S, Bergmann, B, Bernius, C, Berthold, A, Bethke, S, Bhamjee, M, Bhattacharya, DS, Bianchi, RM, Bielski, R, Bitadze, A, Blocker, C, Blumenthal, J, Bogdanchikov, AG, Bohm, C, Boisvert, V, Bokan, P, Booth, CD, Bordulev, IS, Borgna, LS, Bouhova-Thacker, EV, Boyd, J, Boye, D, Boyko, IR, Britton, D, Bruncko, D, Budagov, IA, Bugge, MK, Bullard, BA, Burdin, S, Burton, CD, Buttinger, W, Buzykaev, AR, Cairo, VMM, Calvet, S, Calvetti, M, Cameron, D, Cantero, J, Cardarelli, R, Carminati, L, Carrá, S, Cavalli, N, Centonze, MS, Cerny, K, Cerutti, F, Chan, WY, Chekulaev, SV, Chelkov, GA, Chen, H, Chen, J, Cheong, S, Cheplakov, A, Cherepanova, E, Cheu, E, Chiedde, N, Christopher, LD, Cieri, D, Ciubotaru, DA, Ciungu, BM, Clark, PJ, Columbie, JM Clavijo
• Format: Article
• Language: English
• Subjects: electroweak interaction; particle production; PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; w & z bosons; weak boson production
• ISSN: 2470-0010

The production of a $W$ boson in association with a single charm quark is studied using 140 fb–1 of $\sqrt{s}$ = $13$ $\mathrm{TeV}$ proton-proton collision data collected with the ATLAS detector at the Large Hadron Collider. The charm quark is tagged by the presence of a charmed hadron reconstructed with a secondary-vertex fit. The $W$ boson is reconstructed from the decay to either an electron or a muon and the missing transverse momentum present in the event. The charmed mesons reconstructed are D+ → K– π+ π+ and D*+ → D0 π+ → (K– π+) π+ and the charge conjugate decays in the fiducial regions where $p$T($e,μ$) > 30 GeV, |$η(e,μ)$| < 2.5, $p$T (D(*)) > 8 GeV, and |$η$(D(*))| < 2.2. The integrated and normalized differential cross sections as a function of the pseudorapidity of the lepton from the $W$ boson decay, and of the transverse momentum of the charmed hadron, are extracted from the data using a profile likelihood fit. The measured total fiducial cross sections are ${σ}_{fid}^{OS – SS}$ (W– + D+) = 50.2 ± 0.2 ${(stat)}_{–2.3}^{+2.4}$(syst) pb, ${σ}_{fid}^{OS – SS}$ (W+ + D–) = 48.5 ± 0.2 ${(stat)}_{–2.2}^{+2.3}$(syst) pb, ${σ}_{fid}^{OS – SS}$ (W– + D*+) = 51.1 ± 0.4 ${(stat)}_{–1.8}^{+1.9}$(syst) pb, ${σ}_{fid}^{OS – SS}$ (W+ + D*–) = 50.0 ± 0.4 ${(stat)}_{–1.8}^{+1.9}$(syst) pb. Results are compared with the predictions of next-to-leading-order quantum chromodynamics calculations performed using state-of-the-art parton distribution functions. Additionally, the ratio of charm to anticharm production cross sections is studied to probe the $s$-$\bar{s}$ quark asymmetry. The ratio is found to be ${R}_{c}^{±}$= 0.971 ± 0.006 (stat) ± 0.011 (syst). The ratio and cross-section measurements are consistent with the predictions obtained with parton distribution function sets that have a symmetric $s$-$\bar{s}$ sea, indicating that any $s$-$\bar{s}$ asymmetry in the Bjorken-x region relevant for this measurement is small.