Measurement of ${{\varXi_{cc}^{++}}}$ production in pp collisions at ${\sqrt{ s}=13}$ TeV

Figures(3) / Tables(4)

Get Citation
LHCb Collaboration, R. Aaij, C. Abellán Beteta, T. Ackernley, B. Adeva, M. Adinolfi, H. Afsharnia, C.A. Aidala, S. Aiola, Z. Ajaltouni, S. Akar, P. Albicocco, J. Albrecht, F. Alessio, M. Alexander, A. Alfonso Albero, G. Alkhazov, P. Alvarez Cartelle, A.A. Alves Jr, S. Amato, Y. Amhis, L. An, L. Anderlini, G. Andreassi, M. Andreotti, F. Archilli, A. Artamonov, M. Artuso, K. Arzymatov, E. Aslanides, M. Atzeni, B. Audurier, S. Bachmann, J.J. Back, S. Baker, V. Balagura, W. Baldini, A. Baranov, R.J. Barlow, S. Barsuk, W. Barter, M. Bartolini, F. Baryshnikov, J.M. Basels, G. Bassi, V. Batozskaya, B. Batsukh, A. Battig, A. Bay, M. Becker, F. Bedeschi, I. Bediaga, A. Beiter, L.J. Bel, V. Belavin, S. Belin, V. Bellee, K. Belous, I. Belyaev, G. Bencivenni, E. Ben-Haim, S. Benson, S. Beranek, A. Berezhnoy, R. Bernet, D. Berninghoff, H.C. Bernstein, C. Bertella, E. Bertholet, A. Bertolin, C. Betancourt, F. Betti, M.O. Bettler, Ia. Bezshyiko, S. Bhasin, J. Bhom, M.S. Bieker, S. Bifani, P. Billoir, A. Bizzeti, M. Bjørn, M.P. Blago, T. Blake, F. Blanc, S. Blusk, D. Bobulska, V. Bocci, O. Boente Garcia, T. Boettcher, A. Boldyrev, A. Bondar, N. Bondar, S. Borghi, M. Borisyak, M. Borsato, J.T. Borsuk, T.J.V. Bowcock, C. Bozzi, M.J. Bradley, S. Braun, A. Brea Rodriguez, M. Brodski, J. Brodzicka, A. Brossa Gonzalo, D. Brundu, E. Buchanan, A. Buonaura, C. Burr, A. Bursche, A. Butkevich, J.S. Butter, J. Buytaert, W. Byczynski, S. Cadeddu, H. Cai, R. Calabrese, L. Calero Diaz, S. Cali, R. Calladine, M. Calvi, M. Calvo Gomez, P. Camargo Magalhaes, A. Camboni, P. Campana, D.H. Campora Perez, A.F. Campoverde Quezada, L. Capriotti, A. Carbone, G. Carboni, R. Cardinale, A. Cardini, I. Carli, P. Carniti, K. Carvalho Akiba, A. Casais Vidal, G. Casse, M. Cattaneo, G. Cavallero, S. Celani, R. Cenci, J. Cerasoli, M.G. Chapman, M. Charles, Ph. Charpentier, G. Chatzikonstantinidis, M. Chefdeville, V. Chekalina, C. Chen, S. Chen, A. Chernov, S.-G. Chitic, V. Chobanova, S. Cholak, M. Chrzaszcz, A. Chubykin, P. Ciambrone, M.F. Cicala, X. Cid Vidal, G. Ciezarek, F. Cindolo, P.E.L. Clarke, M. Clemencic, H.V. Cliff, J. Closier, J.L. Cobbledick, V. Coco, J.A.B. Coelho, J. Cogan, E. Cogneras, L. Cojocariu, P. Collins, T. Colombo, A. Comerma-Montells, A. Contu, N. Cooke, G. Coombs, S. Coquereau, G. Corti, C.M. Costa Sobral, B. Couturier, D.C. Craik, J. Crkovska, A. Crocombe, M. Cruz Torres, R. Currie, C.L. Da Silva, E. Dall'Occo, J. Dalseno, C. D'Ambrosio, A. Danilina, P. d'Argent, A. Davis, O. De Aguiar Francisco, K. De Bruyn, S. De Capua, M. De Cian, J.M. De Miranda, L. De Paula, M. De Serio, P. De Simone, J.A. de Vries, C.T. Dean, W. Dean, D. Decamp, L. Del Buono, B. Delaney, H.-P. Dembinski, A. Dendek, V. Denysenko, D. Derkach, O. Deschamps, F. Desse, F. Dettori, B. Dey, A. Di Canto, P. Di Nezza, S. Didenko, H. Dijkstra, V. Dobishuk, F. Dordei, M. Dorigo, A.C. dos Reis, L. Douglas, A. Dovbnya, K. Dreimanis, M.W. Dudek, L. Dufour, G. Dujany, P. Durante, J.M. Durham, D. Dutta, M. Dziewiecki, A. Dziurda, A. Dzyuba, S. Easo, U. Egede, V. Egorychev, S. Eidelman, S. Eisenhardt, R. Ekelhof, S. Ek-In, L. Eklund, S. Ely, A. Ene, E. Epple, S. Escher, S. Esen, T. Evans, A. Falabella, J. Fan, N. Farley, S. Farry, D. Fazzini, P. Fedin, M. Féo, P. Fernandez Declara, A. Fernandez Prieto, F. Ferrari, L. Ferreira Lopes, F. Ferreira Rodrigues, S. Ferreres Sole, M. Ferrillo, M. Ferro-Luzzi, S. Filippov, R.A. Fini, M. Fiorini, M. Firlej, K.M. Fischer, C. Fitzpatrick, T. Fiutowski, F. Fleuret, M. Fontana, F. Fontanelli, R. Forty, V. Franco Lima, M. Franco Sevilla, M. Frank, C. Frei, D.A. Friday, J. Fu, M. Fuehring, W. Funk, E. Gabriel, A. Gallas Torreira, D. Galli, S. Gallorini, S. Gambetta, Y. Gan, M. Gandelman, P. Gandini, Y. Gao, L.M. Garcia Martin, J. García Pardiñas, B. Garcia Plana, F.A. Garcia Rosales, L. Garrido, D. Gascon, C. Gaspar, D. Gerick, E. Gersabeck, M. Gersabeck, T. Gershon, D. Gerstel, Ph. Ghez, V. Gibson, A. Gioventù, O.G. Girard, P. Gironella Gironell, L. Giubega, C. Giugliano, K. Gizdov, V.V. Gligorov, C. Göbel, D. Golubkov, A. Golutvin, A. Gomes, P. Gorbounov, I.V. Gorelov, C. Gotti, E. Govorkova, J.P. Grabowski, R. Graciani Diaz, T. Grammatico, L.A. Granado Cardoso, E. Graugés, E. Graverini, G. Graziani, A. Grecu, R. Greim, P. Griffith, L. Grillo, L. Gruber, B.R. Gruberg Cazon, C. Gu, E. Gushchin, A. Guth, Yu. Guz, T. Gys, P. A. Günther, T. Hadavizadeh, G. Haefeli, C. Haen, S.C. Haines, P.M. Hamilton, Q. Han, X. Han, T.H. Hancock, S. Hansmann-Menzemer, N. Harnew, T. Harrison, R. Hart, C. Hasse, M. Hatch, J. He, M. Hecker, K. Heijhoff, K. Heinicke, A.M. Hennequin, K. Hennessy, L. Henry, J. Heuel, A. Hicheur, D. Hill, M. Hilton, P.H. Hopchev, J. Hu, W. Hu, W. Huang, W. Hulsbergen, T. Humair, R.J. Hunter, M. Hushchyn, D. Hutchcroft, D. Hynds, P. Ibis, M. Idzik, P. Ilten, A. Inglessi, K. Ivshin, R. Jacobsson, S. Jakobsen, E. Jans, B.K. Jashal, A. Jawahery, V. Jevtic, F. Jiang, M. John, D. Johnson, C.R. Jones, B. Jost, N. Jurik, S. Kandybei, M. Karacson, J.M. Kariuki, N. Kazeev, M. Kecke, F. Keizer, M. Kelsey, M. Kenzie, T. Ketel, B. Khanji, A. Kharisova, K.E. Kim, T. Kirn, V.S. Kirsebom, S. Klaver, K. Klimaszewski, S. Koliiev, A. Kondybayeva, A. Konoplyannikov, P. Kopciewicz, R. Kopecna, P. Koppenburg, I. Kostiuk, O. Kot, S. Kotriakhova, L. Kravchuk, R.D. Krawczyk, M. Kreps, F. Kress, S. Kretzschmar, P. Krokovny, W. Krupa, W. Krzemien, W. Kucewicz, M. Kucharczyk, V. Kudryavtsev, H.S. Kuindersma, G.J. Kunde, T. Kvaratskheliya, D. Lacarrere, G. Lafferty, A. Lai, D. Lancierini, J.J. Lane, G. Lanfranchi, C. Langenbruch, O. Lantwin, T. Latham, F. Lazzari, C. Lazzeroni, R. Le Gac, R. Lefèvre, A. Leflat, O. Leroy, T. Lesiak, B. Leverington, H. Li, L. Li, X. Li, Y. Li, Z. Li, X. Liang, R. Lindner, V. Lisovskyi, G. Liu, X. Liu, D. Loh, A. Loi, J. Lomba Castro, I. Longstaff, J.H. Lopes, G. Loustau, G.H. Lovell, Y. Lu, D. Lucchesi, M. Lucio Martinez, Y. Luo, A. Lupato, E. Luppi, O. Lupton, A. Lusiani, X. Lyu, S. Maccolini, F. Machefert, F. Maciuc, V. Macko, P. Mackowiak, S. Maddrell-Mander, L.R. Madhan Mohan, O. Maev, A. Maevskiy, D. Maisuzenko, M.W. Majewski, S. Malde, B. Malecki, A. Malinin, T. Maltsev, H. Malygina, G. Manca, G. Mancinelli, R. Manera Escalero, D. Manuzzi, D. Marangotto, J. Maratas, J.F. Marchand, U. Marconi, S. Mariani, C. Marin Benito, M. Marinangeli, P. Marino, J. Marks, P.J. Marshall, G. Martellotti, L. Martinazzoli, M. Martinelli, D. Martinez Santos, F. Martinez Vidal, A. Massafferri, M. Materok, R. Matev, A. Mathad, Z. Mathe, V. Matiunin, C. Matteuzzi, K.R. Mattioli, A. Mauri, E. Maurice, M. McCann, L. Mcconnell, A. McNab, R. McNulty, J.V. Mead, B. Meadows, C. Meaux, G. Meier, N. Meinert, D. Melnychuk, S. Meloni, M. Merk, A. Merli, M. Mikhasenko, D.A. Milanes, E. Millard, M.-N. Minard, O. Mineev, L. Minzoni, S.E. Mitchell, B. Mitreska, D.S. Mitzel, A. Mödden, A. Mogini, R.D. Moise, T. Mombächer, I.A. Monroy, S. Monteil, M. Morandin, G. Morello, M.J. Morello, J. Moron, A.B. Morris, A.G. Morris, R. Mountain, H. Mu, F. Muheim, M. Mukherjee, M. Mulder, D. Müller, K. Müller, C.H. Murphy, D. Murray, P. Muzzetto, P. Naik, T. Nakada, R. Nandakumar, T. Nanut, I. Nasteva, M. Needham, N. Neri, S. Neubert, N. Neufeld, R. Newcombe, T.D. Nguyen, C. Nguyen-Mau, E.M. Niel, S. Nieswand, N. Nikitin, N.S. Nolte, C. Nunez, A. Oblakowska-Mucha, V. Obraztsov, S. Ogilvy, D.P. O'Hanlon, R. Oldeman, C.J.G. Onderwater, J. D. Osborn, A. Ossowska, J.M. Otalora Goicochea, T. Ovsiannikova, P. Owen, A. Oyanguren, P.R. Pais, T. Pajero, A. Palano, M. Palutan, G. Panshin, A. Papanestis, M. Pappagallo, L.L. Pappalardo, C. Pappenheimer, W. Parker, C. Parkes, G. Passaleva, A. Pastore, M. Patel, C. Patrignani, A. Pearce, A. Pellegrino, M. Pepe Altarelli, S. Perazzini, D. Pereima, P. Perret, L. Pescatore, K. Petridis, A. Petrolini, A. Petrov, S. Petrucci, M. Petruzzo, B. Pietrzyk, G. Pietrzyk, M. Pili, D. Pinci, J. Pinzino, F. Pisani, A. Piucci, V. Placinta, S. Playfer, J. Plews, M. Plo Casasus, F. Polci, M. Poli Lener, M. Poliakova, A. Poluektov, N. Polukhina, I. Polyakov, E. Polycarpo, G.J. Pomery, S. Ponce, A. Popov, D. Popov, S. Poslavskii, K. Prasanth, L. Promberger, C. Prouve, V. Pugatch, A. Puig Navarro, H. Pullen, G. Punzi, W. Qian, J. Qin, R. Quagliani, B. Quintana, N.V. Raab, R.I. Rabadan Trejo, B. Rachwal, J.H. Rademacker, M. Rama, M. Ramos Pernas, M.S. Rangel, F. Ratnikov, G. Raven, M. Reboud, F. Redi, F. Reiss, C. Remon Alepuz, Z. Ren, V. Renaudin, S. Ricciardi, D.S. Richards, S. Richards, K. Rinnert, P. Robbe, A. Robert, A.B. Rodrigues, E. Rodrigues, J.A. Rodriguez Lopez, M. Roehrken, S. Roiser, A. Rollings, V. Romanovskiy, M. Romero Lamas, A. Romero Vidal, J.D. Roth, M. Rotondo, M.S. Rudolph, T. Ruf, J. Ruiz Vidal, A. Ryzhikov, J. Ryzka, J.J. Saborido Silva, N. Sagidova, N. Sahoo, B. Saitta, C. Sanchez Gras, C. Sanchez Mayordomo, R. Santacesaria, C. Santamarina Rios, M. Santimaria, E. Santovetti, G. Sarpis, A. Sarti, C. Satriano, A. Satta, M. Saur, D. Savrina, L.G. Scantlebury Smead, S. Schael, M. Schellenberg, M. Schiller, H. Schindler, M. Schmelling, T. Schmelzer, B. Schmidt, O. Schneider, A. Schopper, H.F. Schreiner, M. Schubiger, S. Schulte, M.H. Schune, R. Schwemmer, B. Sciascia, A. Sciubba, S. Sellam, A. Semennikov, A. Sergi, N. Serra, J. Serrano, L. Sestini, A. Seuthe, P. Seyfert, D.M. Shangase, M. Shapkin, L. Shchutska, T. Shears, L. Shekhtman, V. Shevchenko, E. Shmanin, J.D. Shupperd, B.G. Siddi, R. Silva Coutinho, L. Silva de Oliveira, G. Simi, S. Simone, I. Skiba, N. Skidmore, T. Skwarnicki, M.W. Slater, J.G. Smeaton, A. Smetkina, E. Smith, I.T. Smith, M. Smith, A. Snoch, M. Soares, L. Soares Lavra, M.D. Sokoloff, F.J.P. Soler, B. Souza De Paula, B. Spaan, E. Spadaro Norella, P. Spradlin, F. Stagni, M. Stahl, S. Stahl, P. Stefko, O. Steinkamp, S. Stemmle, O. Stenyakin, M. Stepanova, H. Stevens, S. Stone, S. Stracka, M.E. Stramaglia, M. Straticiuc, S. Strokov, J. Sun, L. Sun, Y. Sun, P. Svihra, K. Swientek, A. Szabelski, T. Szumlak, M. Szymanski, S. Taneja, Z. Tang, T. Tekampe, F. Teubert, E. Thomas, K.A. Thomson, M.J. Tilley, V. Tisserand, S. T'Jampens, M. Tobin, S. Tolk, L. Tomassetti, D. Tonelli, D. Torres Machado, D.Y. Tou, E. Tournefier, M. Traill, M.T. Tran, E. Trifonova, C. Trippl, A. Trisovic, A. Tsaregorodtsev, G. Tuci, A. Tully, N. Tuning, A. Ukleja, A. Usachov, A. Ustyuzhanin, U. Uwer, A. Vagner, V. Vagnoni, A. Valassi, G. Valenti, M. van Beuzekom, H. Van Hecke, E. van Herwijnen, C.B. Van Hulse, M. van Veghel, R. Vazquez Gomez, P. Vazquez Regueiro, C. Vázquez Sierra, S. Vecchi, J.J. Velthuis, M. Veltri, A. Venkateswaran, M. Vernet, M. Veronesi, M. Vesterinen, J.V. Viana Barbosa, D. Vieira, M. Vieites Diaz, H. Viemann, X. Vilasis-Cardona, A. Vitkovskiy, V. Volkov, A. Vollhardt, D. Vom Bruch, A. Vorobyev, V. Vorobyev, N. Voropaev, R. Waldi, J. Walsh, J. Wang, J. Wang, J. Wang, M. Wang, Y. Wang, Z. Wang, D.R. Ward, H.M. Wark, N.K. Watson, D. Websdale, A. Weiden, C. Weisser, B.D.C. Westhenry, D.J. White, M. Whitehead, D. Wiedner, G. Wilkinson, M. Wilkinson, I. Williams, M. Williams, M.R.J. Williams, T. Williams, F.F. Wilson, W. Wislicki, M. Witek, L. Witola, G. Wormser, S.A. Wotton, H. Wu, K. Wyllie, Z. Xiang, D. Xiao, Y. Xie, H. Xing, A. Xu, L. Xu, M. Xu, Q. Xu, Z. Xu, Z. Yang, Z. Yang, Y. Yao, L.E. Yeomans, H. Yin, J. Yu, X. Yuan, O. Yushchenko, K.A. Zarebski, M. Zavertyaev, M. Zdybal, M. Zeng, D. Zhang, L. Zhang, S. Zhang, W.C. Zhang, Y. Zhang, A. Zhelezov, Y. Zheng, X. Zhou, Y. Zhou, X. Zhu, V. Zhukov, J.B. Zonneveld and S. Zucchelli. Measurement of ${{\varXi_{cc}^{++}}}$ production in pp collisions at ${\sqrt{ s}=13}$ TeV[J]. Chinese Physics C, 2020, 44(2): 022001. doi: 10.1088/1674-1137/44/2/022001
LHCb Collaboration, R. Aaij, C. Abellán Beteta, T. Ackernley, B. Adeva, M. Adinolfi, H. Afsharnia, C.A. Aidala, S. Aiola, Z. Ajaltouni, S. Akar, P. Albicocco, J. Albrecht, F. Alessio, M. Alexander, A. Alfonso Albero, G. Alkhazov, P. Alvarez Cartelle, A.A. Alves Jr, S. Amato, Y. Amhis, L. An, L. Anderlini, G. Andreassi, M. Andreotti, F. Archilli, A. Artamonov, M. Artuso, K. Arzymatov, E. Aslanides, M. Atzeni, B. Audurier, S. Bachmann, J.J. Back, S. Baker, V. Balagura, W. Baldini, A. Baranov, R.J. Barlow, S. Barsuk, W. Barter, M. Bartolini, F. Baryshnikov, J.M. Basels, G. Bassi, V. Batozskaya, B. Batsukh, A. Battig, A. Bay, M. Becker, F. Bedeschi, I. Bediaga, A. Beiter, L.J. Bel, V. Belavin, S. Belin, V. Bellee, K. Belous, I. Belyaev, G. Bencivenni, E. Ben-Haim, S. Benson, S. Beranek, A. Berezhnoy, R. Bernet, D. Berninghoff, H.C. Bernstein, C. Bertella, E. Bertholet, A. Bertolin, C. Betancourt, F. Betti, M.O. Bettler, Ia. Bezshyiko, S. Bhasin, J. Bhom, M.S. Bieker, S. Bifani, P. Billoir, A. Bizzeti, M. Bjørn, M.P. Blago, T. Blake, F. Blanc, S. Blusk, D. Bobulska, V. Bocci, O. Boente Garcia, T. Boettcher, A. Boldyrev, A. Bondar, N. Bondar, S. Borghi, M. Borisyak, M. Borsato, J.T. Borsuk, T.J.V. Bowcock, C. Bozzi, M.J. Bradley, S. Braun, A. Brea Rodriguez, M. Brodski, J. Brodzicka, A. Brossa Gonzalo, D. Brundu, E. Buchanan, A. Buonaura, C. Burr, A. Bursche, A. Butkevich, J.S. Butter, J. Buytaert, W. Byczynski, S. Cadeddu, H. Cai, R. Calabrese, L. Calero Diaz, S. Cali, R. Calladine, M. Calvi, M. Calvo Gomez, P. Camargo Magalhaes, A. Camboni, P. Campana, D.H. Campora Perez, A.F. Campoverde Quezada, L. Capriotti, A. Carbone, G. Carboni, R. Cardinale, A. Cardini, I. Carli, P. Carniti, K. Carvalho Akiba, A. Casais Vidal, G. Casse, M. Cattaneo, G. Cavallero, S. Celani, R. Cenci, J. Cerasoli, M.G. Chapman, M. Charles, Ph. Charpentier, G. Chatzikonstantinidis, M. Chefdeville, V. Chekalina, C. Chen, S. Chen, A. Chernov, S.-G. Chitic, V. Chobanova, S. Cholak, M. Chrzaszcz, A. Chubykin, P. Ciambrone, M.F. Cicala, X. Cid Vidal, G. Ciezarek, F. Cindolo, P.E.L. Clarke, M. Clemencic, H.V. Cliff, J. Closier, J.L. Cobbledick, V. Coco, J.A.B. Coelho, J. Cogan, E. Cogneras, L. Cojocariu, P. Collins, T. Colombo, A. Comerma-Montells, A. Contu, N. Cooke, G. Coombs, S. Coquereau, G. Corti, C.M. Costa Sobral, B. Couturier, D.C. Craik, J. Crkovska, A. Crocombe, M. Cruz Torres, R. Currie, C.L. Da Silva, E. Dall'Occo, J. Dalseno, C. D'Ambrosio, A. Danilina, P. d'Argent, A. Davis, O. De Aguiar Francisco, K. De Bruyn, S. De Capua, M. De Cian, J.M. De Miranda, L. De Paula, M. De Serio, P. De Simone, J.A. de Vries, C.T. Dean, W. Dean, D. Decamp, L. Del Buono, B. Delaney, H.-P. Dembinski, A. Dendek, V. Denysenko, D. Derkach, O. Deschamps, F. Desse, F. Dettori, B. Dey, A. Di Canto, P. Di Nezza, S. Didenko, H. Dijkstra, V. Dobishuk, F. Dordei, M. Dorigo, A.C. dos Reis, L. Douglas, A. Dovbnya, K. Dreimanis, M.W. Dudek, L. Dufour, G. Dujany, P. Durante, J.M. Durham, D. Dutta, M. Dziewiecki, A. Dziurda, A. Dzyuba, S. Easo, U. Egede, V. Egorychev, S. Eidelman, S. Eisenhardt, R. Ekelhof, S. Ek-In, L. Eklund, S. Ely, A. Ene, E. Epple, S. Escher, S. Esen, T. Evans, A. Falabella, J. Fan, N. Farley, S. Farry, D. Fazzini, P. Fedin, M. Féo, P. Fernandez Declara, A. Fernandez Prieto, F. Ferrari, L. Ferreira Lopes, F. Ferreira Rodrigues, S. Ferreres Sole, M. Ferrillo, M. Ferro-Luzzi, S. Filippov, R.A. Fini, M. Fiorini, M. Firlej, K.M. Fischer, C. Fitzpatrick, T. Fiutowski, F. Fleuret, M. Fontana, F. Fontanelli, R. Forty, V. Franco Lima, M. Franco Sevilla, M. Frank, C. Frei, D.A. Friday, J. Fu, M. Fuehring, W. Funk, E. Gabriel, A. Gallas Torreira, D. Galli, S. Gallorini, S. Gambetta, Y. Gan, M. Gandelman, P. Gandini, Y. Gao, L.M. Garcia Martin, J. García Pardiñas, B. Garcia Plana, F.A. Garcia Rosales, L. Garrido, D. Gascon, C. Gaspar, D. Gerick, E. Gersabeck, M. Gersabeck, T. Gershon, D. Gerstel, Ph. Ghez, V. Gibson, A. Gioventù, O.G. Girard, P. Gironella Gironell, L. Giubega, C. Giugliano, K. Gizdov, V.V. Gligorov, C. Göbel, D. Golubkov, A. Golutvin, A. Gomes, P. Gorbounov, I.V. Gorelov, C. Gotti, E. Govorkova, J.P. Grabowski, R. Graciani Diaz, T. Grammatico, L.A. Granado Cardoso, E. Graugés, E. Graverini, G. Graziani, A. Grecu, R. Greim, P. Griffith, L. Grillo, L. Gruber, B.R. Gruberg Cazon, C. Gu, E. Gushchin, A. Guth, Yu. Guz, T. Gys, P. A. Günther, T. Hadavizadeh, G. Haefeli, C. Haen, S.C. Haines, P.M. Hamilton, Q. Han, X. Han, T.H. Hancock, S. Hansmann-Menzemer, N. Harnew, T. Harrison, R. Hart, C. Hasse, M. Hatch, J. He, M. Hecker, K. Heijhoff, K. Heinicke, A.M. Hennequin, K. Hennessy, L. Henry, J. Heuel, A. Hicheur, D. Hill, M. Hilton, P.H. Hopchev, J. Hu, W. Hu, W. Huang, W. Hulsbergen, T. Humair, R.J. Hunter, M. Hushchyn, D. Hutchcroft, D. Hynds, P. Ibis, M. Idzik, P. Ilten, A. Inglessi, K. Ivshin, R. Jacobsson, S. Jakobsen, E. Jans, B.K. Jashal, A. Jawahery, V. Jevtic, F. Jiang, M. John, D. Johnson, C.R. Jones, B. Jost, N. Jurik, S. Kandybei, M. Karacson, J.M. Kariuki, N. Kazeev, M. Kecke, F. Keizer, M. Kelsey, M. Kenzie, T. Ketel, B. Khanji, A. Kharisova, K.E. Kim, T. Kirn, V.S. Kirsebom, S. Klaver, K. Klimaszewski, S. Koliiev, A. Kondybayeva, A. Konoplyannikov, P. Kopciewicz, R. Kopecna, P. Koppenburg, I. Kostiuk, O. Kot, S. Kotriakhova, L. Kravchuk, R.D. Krawczyk, M. Kreps, F. Kress, S. Kretzschmar, P. Krokovny, W. Krupa, W. Krzemien, W. Kucewicz, M. Kucharczyk, V. Kudryavtsev, H.S. Kuindersma, G.J. Kunde, T. Kvaratskheliya, D. Lacarrere, G. Lafferty, A. Lai, D. Lancierini, J.J. Lane, G. Lanfranchi, C. Langenbruch, O. Lantwin, T. Latham, F. Lazzari, C. Lazzeroni, R. Le Gac, R. Lefèvre, A. Leflat, O. Leroy, T. Lesiak, B. Leverington, H. Li, L. Li, X. Li, Y. Li, Z. Li, X. Liang, R. Lindner, V. Lisovskyi, G. Liu, X. Liu, D. Loh, A. Loi, J. Lomba Castro, I. Longstaff, J.H. Lopes, G. Loustau, G.H. Lovell, Y. Lu, D. Lucchesi, M. Lucio Martinez, Y. Luo, A. Lupato, E. Luppi, O. Lupton, A. Lusiani, X. Lyu, S. Maccolini, F. Machefert, F. Maciuc, V. Macko, P. Mackowiak, S. Maddrell-Mander, L.R. Madhan Mohan, O. Maev, A. Maevskiy, D. Maisuzenko, M.W. Majewski, S. Malde, B. Malecki, A. Malinin, T. Maltsev, H. Malygina, G. Manca, G. Mancinelli, R. Manera Escalero, D. Manuzzi, D. Marangotto, J. Maratas, J.F. Marchand, U. Marconi, S. Mariani, C. Marin Benito, M. Marinangeli, P. Marino, J. Marks, P.J. Marshall, G. Martellotti, L. Martinazzoli, M. Martinelli, D. Martinez Santos, F. Martinez Vidal, A. Massafferri, M. Materok, R. Matev, A. Mathad, Z. Mathe, V. Matiunin, C. Matteuzzi, K.R. Mattioli, A. Mauri, E. Maurice, M. McCann, L. Mcconnell, A. McNab, R. McNulty, J.V. Mead, B. Meadows, C. Meaux, G. Meier, N. Meinert, D. Melnychuk, S. Meloni, M. Merk, A. Merli, M. Mikhasenko, D.A. Milanes, E. Millard, M.-N. Minard, O. Mineev, L. Minzoni, S.E. Mitchell, B. Mitreska, D.S. Mitzel, A. Mödden, A. Mogini, R.D. Moise, T. Mombächer, I.A. Monroy, S. Monteil, M. Morandin, G. Morello, M.J. Morello, J. Moron, A.B. Morris, A.G. Morris, R. Mountain, H. Mu, F. Muheim, M. Mukherjee, M. Mulder, D. Müller, K. Müller, C.H. Murphy, D. Murray, P. Muzzetto, P. Naik, T. Nakada, R. Nandakumar, T. Nanut, I. Nasteva, M. Needham, N. Neri, S. Neubert, N. Neufeld, R. Newcombe, T.D. Nguyen, C. Nguyen-Mau, E.M. Niel, S. Nieswand, N. Nikitin, N.S. Nolte, C. Nunez, A. Oblakowska-Mucha, V. Obraztsov, S. Ogilvy, D.P. O'Hanlon, R. Oldeman, C.J.G. Onderwater, J. D. Osborn, A. Ossowska, J.M. Otalora Goicochea, T. Ovsiannikova, P. Owen, A. Oyanguren, P.R. Pais, T. Pajero, A. Palano, M. Palutan, G. Panshin, A. Papanestis, M. Pappagallo, L.L. Pappalardo, C. Pappenheimer, W. Parker, C. Parkes, G. Passaleva, A. Pastore, M. Patel, C. Patrignani, A. Pearce, A. Pellegrino, M. Pepe Altarelli, S. Perazzini, D. Pereima, P. Perret, L. Pescatore, K. Petridis, A. Petrolini, A. Petrov, S. Petrucci, M. Petruzzo, B. Pietrzyk, G. Pietrzyk, M. Pili, D. Pinci, J. Pinzino, F. Pisani, A. Piucci, V. Placinta, S. Playfer, J. Plews, M. Plo Casasus, F. Polci, M. Poli Lener, M. Poliakova, A. Poluektov, N. Polukhina, I. Polyakov, E. Polycarpo, G.J. Pomery, S. Ponce, A. Popov, D. Popov, S. Poslavskii, K. Prasanth, L. Promberger, C. Prouve, V. Pugatch, A. Puig Navarro, H. Pullen, G. Punzi, W. Qian, J. Qin, R. Quagliani, B. Quintana, N.V. Raab, R.I. Rabadan Trejo, B. Rachwal, J.H. Rademacker, M. Rama, M. Ramos Pernas, M.S. Rangel, F. Ratnikov, G. Raven, M. Reboud, F. Redi, F. Reiss, C. Remon Alepuz, Z. Ren, V. Renaudin, S. Ricciardi, D.S. Richards, S. Richards, K. Rinnert, P. Robbe, A. Robert, A.B. Rodrigues, E. Rodrigues, J.A. Rodriguez Lopez, M. Roehrken, S. Roiser, A. Rollings, V. Romanovskiy, M. Romero Lamas, A. Romero Vidal, J.D. Roth, M. Rotondo, M.S. Rudolph, T. Ruf, J. Ruiz Vidal, A. Ryzhikov, J. Ryzka, J.J. Saborido Silva, N. Sagidova, N. Sahoo, B. Saitta, C. Sanchez Gras, C. Sanchez Mayordomo, R. Santacesaria, C. Santamarina Rios, M. Santimaria, E. Santovetti, G. Sarpis, A. Sarti, C. Satriano, A. Satta, M. Saur, D. Savrina, L.G. Scantlebury Smead, S. Schael, M. Schellenberg, M. Schiller, H. Schindler, M. Schmelling, T. Schmelzer, B. Schmidt, O. Schneider, A. Schopper, H.F. Schreiner, M. Schubiger, S. Schulte, M.H. Schune, R. Schwemmer, B. Sciascia, A. Sciubba, S. Sellam, A. Semennikov, A. Sergi, N. Serra, J. Serrano, L. Sestini, A. Seuthe, P. Seyfert, D.M. Shangase, M. Shapkin, L. Shchutska, T. Shears, L. Shekhtman, V. Shevchenko, E. Shmanin, J.D. Shupperd, B.G. Siddi, R. Silva Coutinho, L. Silva de Oliveira, G. Simi, S. Simone, I. Skiba, N. Skidmore, T. Skwarnicki, M.W. Slater, J.G. Smeaton, A. Smetkina, E. Smith, I.T. Smith, M. Smith, A. Snoch, M. Soares, L. Soares Lavra, M.D. Sokoloff, F.J.P. Soler, B. Souza De Paula, B. Spaan, E. Spadaro Norella, P. Spradlin, F. Stagni, M. Stahl, S. Stahl, P. Stefko, O. Steinkamp, S. Stemmle, O. Stenyakin, M. Stepanova, H. Stevens, S. Stone, S. Stracka, M.E. Stramaglia, M. Straticiuc, S. Strokov, J. Sun, L. Sun, Y. Sun, P. Svihra, K. Swientek, A. Szabelski, T. Szumlak, M. Szymanski, S. Taneja, Z. Tang, T. Tekampe, F. Teubert, E. Thomas, K.A. Thomson, M.J. Tilley, V. Tisserand, S. T'Jampens, M. Tobin, S. Tolk, L. Tomassetti, D. Tonelli, D. Torres Machado, D.Y. Tou, E. Tournefier, M. Traill, M.T. Tran, E. Trifonova, C. Trippl, A. Trisovic, A. Tsaregorodtsev, G. Tuci, A. Tully, N. Tuning, A. Ukleja, A. Usachov, A. Ustyuzhanin, U. Uwer, A. Vagner, V. Vagnoni, A. Valassi, G. Valenti, M. van Beuzekom, H. Van Hecke, E. van Herwijnen, C.B. Van Hulse, M. van Veghel, R. Vazquez Gomez, P. Vazquez Regueiro, C. Vázquez Sierra, S. Vecchi, J.J. Velthuis, M. Veltri, A. Venkateswaran, M. Vernet, M. Veronesi, M. Vesterinen, J.V. Viana Barbosa, D. Vieira, M. Vieites Diaz, H. Viemann, X. Vilasis-Cardona, A. Vitkovskiy, V. Volkov, A. Vollhardt, D. Vom Bruch, A. Vorobyev, V. Vorobyev, N. Voropaev, R. Waldi, J. Walsh, J. Wang, J. Wang, J. Wang, M. Wang, Y. Wang, Z. Wang, D.R. Ward, H.M. Wark, N.K. Watson, D. Websdale, A. Weiden, C. Weisser, B.D.C. Westhenry, D.J. White, M. Whitehead, D. Wiedner, G. Wilkinson, M. Wilkinson, I. Williams, M. Williams, M.R.J. Williams, T. Williams, F.F. Wilson, W. Wislicki, M. Witek, L. Witola, G. Wormser, S.A. Wotton, H. Wu, K. Wyllie, Z. Xiang, D. Xiao, Y. Xie, H. Xing, A. Xu, L. Xu, M. Xu, Q. Xu, Z. Xu, Z. Yang, Z. Yang, Y. Yao, L.E. Yeomans, H. Yin, J. Yu, X. Yuan, O. Yushchenko, K.A. Zarebski, M. Zavertyaev, M. Zdybal, M. Zeng, D. Zhang, L. Zhang, S. Zhang, W.C. Zhang, Y. Zhang, A. Zhelezov, Y. Zheng, X. Zhou, Y. Zhou, X. Zhu, V. Zhukov, J.B. Zonneveld and S. Zucchelli. Measurement of ${{\varXi_{cc}^{++}}}$ production in pp collisions at ${\sqrt{ s}=13}$ TeV[J]. Chinese Physics C, 2020, 44(2): 022001.  doi: 10.1088/1674-1137/44/2/022001 shu
Milestone
Received: 2019-10-25
Article Metric

Article Views(565)
PDF Downloads(77)
Cited by(0)
Policy on re-use
To reuse of Open Access content published by CPC, for content published under the terms of the Creative Commons Attribution 3.0 license (“CC CY”), the users don’t need to request permission to copy, distribute and display the final published version of the article and to create derivative works, subject to appropriate attribution.
通讯作者: 陈斌, bchen63@163.com
  • 1. 

    沈阳化工大学材料科学与工程学院 沈阳 110142

  1. 本站搜索
  2. 百度学术搜索
  3. 万方数据库搜索
  4. CNKI搜索

Email This Article

Title:
Email:

Measurement of ${{\varXi_{cc}^{++}}}$ production in pp collisions at ${\sqrt{ s}=13}$ TeV

  • 1. Centro Brasileiro de Pesquisas Físicas (CBPF), Rio de Janeiro, Brazil
  • 2. Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil
  • 3. Center for High Energy Physics, Tsinghua University, Beijing, China
  • 4. School of Physics State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, China
  • 5. University of Chinese Academy of Sciences, Beijing, China
  • 6. Institute Of High Energy Physics (IHEP), Beijing, China
  • 7. Institute of Particle Physics, Central China Normal University, Wuhan, Hubei, China
  • 8. Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IN2P3-LAPP, Annecy, France
  • 9. Université Clermont Auvergne, CNRS/IN2P3, LPC, Clermont-Ferrand, France
  • 10. Aix Marseille Univ, CNRS/IN2P3, CPPM, Marseille, France
  • 11. LAL, Univ. Paris-Sud, CNRS/IN2P3, Université Paris-Saclay, Orsay, France
  • 12. LPNHE, Sorbonne Université, Paris Diderot Sorbonne Paris Cité, CNRS/IN2P3, Paris, France
  • 13. I. Physikalisches Institut, RWTH Aachen University, Aachen, Germany
  • 14. Fakultät Physik, Technische Universität Dortmund, Dortmund, Germany
  • 15. Max-Planck-Institut für Kernphysik (MPIK), Heidelberg, Germany
  • 16. Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
  • 17. School of Physics, University College Dublin, Dublin, Ireland
  • 18. INFN Sezione di Bari, Bari, Italy
  • 19. INFN Sezione di Bologna, Bologna, Italy
  • 20. INFN Sezione di Ferrara, Ferrara, Italy
  • 21. INFN Sezione di Firenze, Firenze, Italy
  • 22. INFN Laboratori Nazionali di Frascati, Frascati, Italy
  • 23. INFN Sezione di Genova, Genova, Italy
  • 24. INFN Sezione di Milano-Bicocca, Milano, Italy
  • 25. INFN Sezione di Milano, Milano, Italy
  • 26. INFN Sezione di Cagliari, Monserrato, Italy
  • 27. INFN Sezione di Padova, Padova, Italy
  • 28. INFN Sezione di Pisa, Pisa, Italy
  • 29. INFN Sezione di Roma Tor Vergata, Roma, Italy
  • 30. INFN Sezione di Roma La Sapienza, Roma, Italy
  • 31. Nikhef National Institute for Subatomic Physics, Amsterdam, Netherlands
  • 32. Nikhef National Institute for Subatomic Physics and VU University Amsterdam, Amsterdam, Netherlands
  • 33. Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences, Kraków, Poland
  • 34. AGH - University of Science and Technology, Faculty of Physics and Applied Computer Science, Kraków, Poland
  • 35. National Center for Nuclear Research (NCBJ), Warsaw, Poland
  • 36. Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest-Magurele, Romania
  • 37. Petersburg Nuclear Physics Institute NRC Kurchatov Institute (PNPI NRC KI), Gatchina, Russia
  • 38. Institute of Theoretical and Experimental Physics NRC Kurchatov Institute (ITEP NRC KI), Moscow, Russia, Moscow, Russia
  • 39. Institute of Nuclear Physics, Moscow State University (SINP MSU), Moscow, Russia
  • 40. Institute for Nuclear Research of the Russian Academy of Sciences (INR RAS), Moscow, Russia
  • 41. Yandex School of Data Analysis, Moscow, Russia
  • 42. Budker Institute of Nuclear Physics (SB RAS), Novosibirsk, Russia
  • 43. Institute for High Energy Physics NRC Kurchatov Institute (IHEP NRC KI), Protvino, Russia, Protvino, Russia
  • 44. ICCUB, Universitat de Barcelona, Barcelona, Spain
  • 45. Instituto Galego de Física de Altas Enerxías (IGFAE), Universidade de Santiago de Compostela, Santiago de Compostela, Spain
  • 46. Instituto de Fisica Corpuscular, Centro Mixto Universidad de Valencia - CSIC, Valencia, Spain
  • 47. European Organization for Nuclear Research (CERN), Geneva, Switzerland
  • 48. Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
  • 49. Physik-Institut, Universität Zürich, Zürich, Switzerland
  • 50. NSC Kharkiv Institute of Physics and Technology (NSC KIPT), Kharkiv, Ukraine
  • 51. Institute for Nuclear Research of the National Academy of Sciences (KINR), Kyiv, Ukraine
  • 52. University of Birmingham, Birmingham, United Kingdom
  • 53. H.H. Wills Physics Laboratory, University of Bristol, Bristol, United Kingdom
  • 54. Cavendish Laboratory, University of Cambridge, Cambridge, United Kingdom
  • 55. Department of Physics, University of Warwick, Coventry, United Kingdom
  • 56. STFC Rutherford Appleton Laboratory, Didcot, United Kingdom
  • 57. School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
  • 58. School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom
  • 59. Oliver Lodge Laboratory, University of Liverpool, Liverpool, United Kingdom
  • 60. Imperial College London, London, United Kingdom
  • 61. Department of Physics and Astronomy, University of Manchester, Manchester, United Kingdom
  • 62. Department of Physics, University of Oxford, Oxford, United Kingdom
  • 63. Massachusetts Institute of Technology, Cambridge, MA, United States
  • 64. University of Cincinnati, Cincinnati, OH, United States
  • 65. University of Maryland, College Park, MD, United States
  • 66. Los Alamos National Laboratory (LANL), Los Alamos, United States
  • 67. Syracuse University, Syracuse, NY, United States
  • 68. Laboratory of Mathematical and Subatomic Physics , Constantine, Algeria, associated to 2
  • 69. School of Physics and Astronomy, Monash University, Melbourne, Australia, associated to 55
  • 70. Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), Rio de Janeiro, Brazil, associated to 2
  • 71. South China Normal University, Guangzhou, China, associated to 3
  • 72. School of Physics and Technology, Wuhan University, Wuhan, China, associated to 3
  • 73. Departamento de Fisica , Universidad Nacional de Colombia, Bogota, Colombia, associated to 12
  • 74. Institut für Physik, Universität Rostock, Rostock, Germany, associated to 16
  • 75. Van Swinderen Institute, University of Groningen, Groningen, Netherlands, associated to 31
  • 76. National Research Centre Kurchatov Institute, Moscow, Russia, associated to 38
  • 77. National University of Science and Technology "MISIS", Moscow, Russia, associated to 38
  • 78. National Research University Higher School of Economics, Moscow, Russia, associated to 41
  • 79. National Research Tomsk Polytechnic University, Tomsk, Russia, associated to 38
  • 80. University of Michigan, Ann Arbor, United States, associated to 67
  • a. Universidade Federal do Trióngulo Mineiro (UFTM), Uberaba-MG, Brazil
  • b. Laboratoire Leprince-Ringuet, Palaiseau, France
  • c. P.N. Lebedev Physical Institute, Russian Academy of Science (LPI RAS), Moscow, Russia
  • d. Università di Bari, Bari, Italy
  • e. Università di Bologna, Bologna, Italy
  • f. Università di Cagliari, Cagliari, Italy
  • g. Università di Ferrara, Ferrara, Italy
  • h. Università di Genova, Genova, Italy
  • i. Università di Milano Bicocca, Milano, Italy
  • j. Università di Roma Tor Vergata, Roma, Italy
  • k. Università di Roma La Sapienza, Roma, Italy
  • l. AGH - University of Science and Technology, Faculty of Computer Science, Electronics and Telecommunications, Kraków, Poland
  • m. DS4DS, La Salle, Universitat Ramon Llull, Barcelona, Spain
  • n. Hanoi University of Science, Hanoi, Vietnam
  • o. Università di Padova, Padova, Italy
  • p. Università di Pisa, Pisa, Italy
  • q. Università degli Studi di Milano, Milano, Italy
  • r. Università di Urbino, Urbino, Italy
  • s. Università della Basilicata, Potenza, Italy
  • t. Scuola Normale Superiore, Pisa, Italy
  • u. Università di Modena e Reggio Emilia, Modena, Italy
  • v. Università di Siena, Siena, Italy
  • w. MSU - Iligan Institute of Technology (MSU-IIT), Iligan, Philippines
  • x. Novosibirsk State University, Novosibirsk, Russia
  • y. INFN Sezione di Trieste, Trieste, Italy
  • z. School of Physics and Information Technology, Shaanxi Normal University (SNNU), Xi'an, China
  • aa. Physics and Micro Electronic College, Hunan University, Changsha City, China
  • ab. Universidad Nacional Autonoma de Honduras, Tegucigalpa, Honduras

Abstract: The production of $\varXi _{cc}^ {++}$ baryons in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=13\;{\rm{TeV}}$ is measured in the transverse-momentum range $4 < p_{\rm{T}} <15\;{\rm{GeV}}/c$ and the rapidity range $2.0 <y <4.5$. The data used in this measurement correspond to an integrated luminosity of $1.7\;{\rm{fb}}^{-1}$, recorded by the LHCb experiment during 2016. The ratio of the $\varXi _{cc}^ {++}$ production cross-section times the branching fraction of the $\varXi _{cc}^ {++} \to \varLambda _c^ + K^-\pi^+ \pi^+$ decay relative to the prompt $\varLambda _c^ + $ production cross-section is found to be $(2.22\pm 0.27 \pm 0.29)\times 10^{-4}$, assuming the central value of the measured $\varXi _{cc}^ {++}$ lifetime, where the first uncertainty is statistical and the second systematic.

    HTML

    1.   Introduction
    • The quark model [1,2] predicts the existence of multiplets of baryon and meson states. Baryons containing two charm quarks and a light quark provide a unique system for testing the low-energy limit of quantum chromodynamics (QCD). The production of doubly charmed baryons at hadron colliders can be treated as two independent processes: production of a $cc$ diquark followed by the hadronisation of the diquark into a baryon [3-9]. The production cross-section of doubly charmed baryons in proton-proton collisions at a centre-of-mass energy $\sqrt{s} = 13\;{\rm{TeV}}$ is predicted to be in the range 60–1800 nb [3-9], which is between $10^{-4}$ and $10^{-3}$ times that of the total charm production [4].

      A doubly charmed baryon was first reported by the SELEX collaboration [10,11]. They found that 20% of their $\varLambda _c^ +$ yield originated from $\varXi _{cc}^ +$ decays, which is several orders of magnitude higher than theoretical prediction [4]. However, this signal has not been confirmed by searches performed at the FOCUS [12], BaBar [13], Belle [14], and LHCb [15,16] experiments. Recently, the LHCb collaboration observed a peak in the $\varLambda _c^ + {K^ - }{\pi ^ + }{\pi ^ + }$ mass spectrum at a mass of $3621.40 \pm 0.78\;{\rm{MeV}}/{c^2}$ [17], consistent with expectations for the $\varXi _{cc}^ {++}$ baryon. The $\varXi _{cc}^ {++}$ lifetime was measured to be $0.256^{+0.024}_{-0.022}\; ({\rm{stat}}) \;\pm 0.014$ $ \;({\rm{syst}})\;{\rm{ps}}$ [18], indicating that it decays through the weak interaction. A new decay mode, $\varXi _{cc}^{ + + } \to \varXi _c^ + {\pi ^ + }$, was observed by the LHCb collaboration [19], and the measured $\varXi _{cc}^ {++}$ mass was found to be consistent with that measured using $\varXi _{cc}^{ + + } \to \varLambda _c^ + {K^ - }{\pi ^ + }{\pi ^ + }$ decays. The $\varXi _{cc}^{ + + } \to {D^ + }p{K^ - }{\pi ^ + }$ decay has been searched for, but no signal was found [20].

      This paper presents a measurement of $\varXi _{cc}^{ + + }$ production in $pp$ collisions at a centre-of-mass energy of $\sqrt{s}=13\;{\rm{TeV}}$, following the same analysis strategy as that used in Refs. [15,17,18]. The $\varXi _{cc}^ {++}$ production cross-section, $\sigma \left( {\varXi _{cc}^{ + + }} \right)$, times the branching fraction of the $\varXi _{cc}^{ + + } \to \varLambda _c^ + {K^ - }{\pi ^ + }{\pi ^ + }$ decay, is measured relative to the prompt $\varLambda _c^ +$ production cross-section, $\sigma \left( {\varLambda _c^ + } \right)$, in the transverse momentum range $4<{p_{\rm{T}}}<15\;{\rm{GeV}}/ c$ and the rapidity range $2.0<y<4.5$. The data used correspond to an integrated luminosity of $1.7\;{\rm{f}}{{\rm{b}}^{ - 1}}$ collected by the LHCb experiment in 2016. The $\varLambda _c^ +$ baryon is reconstructed via the $\varLambda_{c}^{+} \rightarrow p K^{-} \pi^{+}$ decay. The inclusion of the charge-conjugate decay processes is implied throughout this paper. The production rate ratio is defined as,

      $ R \equiv \frac{{\sigma \left( {\varXi _{cc}^{ + + }} \right) \times {\cal B}\left( {\varXi _{cc}^{ + + } \to \varLambda _c^ + {K^ - }{\pi ^ + }{\pi ^ + }} \right)}}{{\sigma \left( {\varLambda _c^ + } \right)}} = \frac{{{N_{{\rm{sig}}}}}}{{{N_{{\rm{norm}}}}}}\frac{{{\varepsilon _{{\rm{norm}}}}}}{{{\varepsilon _{{\rm{sig}}}}}}, $

      (1)

      where “sig” and “norm” refer to the signal ($\varXi _{cc}^{ + + }$) and normalisation $\left( {\varLambda _c^ + } \right)$ modes, N is the signal yield and $\varepsilon$ is the total efficiency to reconstruct and select these decays.

    2.   Detector and simulation
    • The LHCb detector [21,22] is a single-arm forward spectrometer covering the pseudorapidity range $2<\eta <5$, designed for the study of particles containing b or c quarks. The detector includes a high-precision tracking system consisting of a silicon-strip vertex detector surrounding the $pp$ interaction region [23], a large-area silicon-strip detector located upstream of a dipole magnet with a bending power of about 4 Tm, and three stations of silicon-strip detectors and straw drift tubes [24] placed downstream of the magnet. The tracking system provides a measurement of the momentum, p, of charged particles with a relative uncertainty that varies from 0.5% at low momentum to 1.0% at $200\;{\rm GeV}/c$. The minimum distance of a track to a primary vertex, the impact parameter, is measured with a resolution of $(15+29/{p_{\rm{T}}})$ µm, where ${p_{\rm{T}}}$ is expressed in ${\rm GeV}/c $. Different types of charged hadrons are distinguished using information from two ring-imaging Cherenkov detectors [25]. Photons, electrons and hadrons are identified by a calorimeter system consisting of scintillating-pad (SPD) and preshower detectors, an electromagnetic and a hadronic calorimeter. Muons are identified by a system composed of alternating layers of iron and multiwire proportional chambers [26]. The online event selection is performed by a trigger [27], which consists of a hardware stage, based on information from the calorimeters and muon systems [28,29], followed by a software stage, which applies a full event reconstruction incorporating near-real-time alignment and calibration of the detector [30]. The output of the reconstruction performed in the software trigger [31] is used as input to the present analysis.

      Simulated samples are required to develop the candidate selection and to estimate the efficiency of the detector acceptance and the imposed selection requirements. Simulated $pp$ collisions are generated using Pythia [32] with a specific LHCb configuration [33]. A dedicated package, GenXicc2.0 [34], is used to simulate the $\varXi _{cc}^{ + + }$ baryon production. Decays of unstable particles are described by EvtGen [35], in which final-state radiation is generated using Photos [36]. The interaction of the generated particles with the detector, and its response, are simulated using the Geant4 toolkit [37] as described in Ref. [38].

    3.   Event selection
    • The $\varLambda _c^ + \to p{K^ - }{\pi ^ + }$ candidate is reconstructed through three charged particles identified as p, ${K^ - }$ and ${\pi ^ + }$ hadrons, which form a common vertex and do not originate from any primary vertex (PV) in the event. The decay vertex of the $\varLambda _c^ +$ candidate is required to be displaced from any PV by requiring its proper decay time to be greater than 0.15 ps, corresponding to about 1.5 times the $\varLambda _c^ +$ decay time resolution [39]. Each $\varLambda _c^ +$ candidate with mass in the range 2270-2306 ${\rm{MeV }}/c^2 $ is then combined with three additional particles to form a $\varXi _{cc}^{ + + }$ candidate. The three particles must form a common vertex with the $\varLambda _c^ +$ candidate and have hadron-identification information consistent with them being two ${\pi ^ + }$ mesons and one ${K^ - }$ meson. The $\varLambda _c^ +$ decay vertex is required to be downstream of the $\varXi _{cc}^{ + + }$ vertex. Additionally, the $\varXi _{cc}^ {++}$ candidates must have ${p_{\rm{T}}} > 4 \;{\rm GeV}/c $ and originate from a PV.

      The combinatorial background is suppressed using two multivariate classifiers based on a boosted decision tree algorithm [40]. One classifier is optimised to select $\varLambda _c^ +$ candidates irrespective of their origin, and the other is optimised to select $\varXi _{cc}^ {++}$ candidates. While both classifiers are applied to the signal channel, only the first is applied to the normalisation decay channel. The first classifier is trained with $\varLambda _c^ +$ signal in the simulated $\varXi _{cc}^ {++}$ sample and background candidates in the $\varLambda _c^ +$ mass sideband. The second classifier is trained using data candidates in the $\varLambda _c^ +$ and $\varXi _{cc}^ {++}$ signal mass region, where wrong-sign (WS) $\varLambda _c^ + {K^ - }{\pi ^ + }{\pi ^ - }$ combinations are used as proxy for the background. The first multivariate classifier is trained with the following variables: the $\chi^2$ of the $\varLambda _c^ +$ vertex fit; the largest distance of closest approach among the decay products; the scalar sum of the ${p_{\rm{T}}}$ and the smallest ${p_{\rm{T}}}$ of the three decay products of the $\varLambda _c^ +$ candidate; the smallest and largest $\chi _{{\rm{IP}}}^2$ of the decay products of the $\varLambda _c^ +$ candidate with respect to its PV. Here, $\chi _{{\rm{IP}}}^2$ is defined as the difference in $\chi^2$ of the PV fit with and without the particle in question. The PV of any single particle is defined to be that with respect to which the particle has the smallest $\chi _{{\rm{IP}}}^2$. The second multivariate classifier is trained with the following variables: the $\chi _{{\rm{IP}}}^2$ of the $\varXi _{cc}^{ + + }$ candidate to its PV; the angle between the $\varXi _{cc}^{ + + }$ momentum and the direction from the PV to the $\varXi _{cc}^{ + + }$ decay vertex; the logarithm of the $\chi^2$ of the $\varXi _{cc}^ {++}$ flight distance between the $\varXi _{cc}^ {++}$ decay vertex and the PV; the vertex fit ${\chi ^2}$ of the $\varXi _{cc}^{ + + }$ candidate; the ${\chi ^2}$ of a kinematic refit [41] that requires the $\varXi _{cc}^{ + + }$ candidate to originate from a PV; the scalar sum of the ${p_{\rm{T}}}$ and the smallest ${p_{\rm{T}}}$ of the six final state tracks of the $\varXi _{cc}^{ + + }$ candidate. Here the flight distance $\chi^2$ is defined as the change in $\chi^2$ of the $\varXi _{cc}^ {++}$ decay vertex if it is constrained to coincide with the PV. Candidates retained for analysis must have two classifier responses exceeding thresholds chosen by performing a two-dimensional maximisation of the figure of merit $\varepsilon/(5/2+\sqrt{B})$ [42]. Here $\varepsilon$ and B are the estimated signal efficiency determined from signal simulation and background yield under the signal peak, respectively. The background is estimated from the WS sample. The same threshold of the first classifier, optimised for the signal mode, is applied to the normalisation mode.

      Finally, the $\varXi _{cc}^{ + + }$ and $\varLambda _c^ +$ candidates are required to have their transverse momentum and rapidity in the fiducial ranges of 4-15 ${\rm GeV}/c $ and 2.0-4.5, respectively. After the multivariate selection is applied, events may still contain more than one $\varXi _{cc}^ {++}$ candidate in the signal region. Candidates made of duplicate tracks are removed by requiring all pairs of tracks with the same charge to have an opening angle larger than $0.5 \;{\rm{ mrad }}$. Duplicate candidates, which are due to the interchange between identical particles from the $\varLambda _c^ +$ decay or directly from the $\varXi _{cc}^{ + + }$ decay (e.g., the ${K^ - }$ particle from the $\varXi _{cc}^{ + + }$ decay and the ${K^ - }$ particle from the $\varLambda _c^ +$ decay), can cause peaking structures in the $\varXi _{cc}^ {++}$ invariant mass distribution. In this case, one of the candidates is chosen at random to be retained and the others are discarded. The systematic uncertainty associated with this procedure is negligible.

    4.   Signal yields
    • After the full selection is applied, the data sets are further filtered into two disjoint subsamples using information from the hardware trigger. The first contains candidates that are triggered by at least one of the $\varLambda _c^ +$ decay products with high transverse energy deposited in the calorimeters, referred to as Triggered On Signal (TOS). The second consists of the events that are exclusively triggered by particles unrelated to the signal decay products; these events can, for example, be triggered by the decay products of the charmed hadrons produced together with the signal baryon, referred to as exclusively Triggered Independently of Signal (exTIS).

      To determine the $\varXi _{cc}^ {++}$ baryon signal yields, an unbinned extended maximum-likelihood fit is performed simultaneously to the $\varLambda _c^ + {K^ - }{\pi ^ + }{\pi ^ + }$ invariant-mass spectra in the interval 3470-3770 ${\rm{MeV}}/c^2 $ of the two trigger categories. The mass distribution of the signal is described by the sum of a Gaussian function and a modified Gaussian function with power-law tails on both sides of the function [43] with a common peak position. The tail parameters and the relative fraction of the two Gaussian functions for the signal model are determined from simulation, while the common peak position and the mass resolution are allowed to vary in the fit. The background is described by a second-order Chebyshev polynomial. Fig. 1 shows the $\varLambda _c^ + {K^ - }{\pi ^ + }{\pi ^ + }$ invariant-mass distribution in data together with the fit results for the two trigger categories. The fit returns a mass of $3621.34 \pm 0.74 \;{\rm{MeV}}/ c^2 $, and a mass resolution of $7.1 \pm 1.3 \;{\rm{MeV}}/c^2 $, where the uncertainties are statistical only.

      Figure 1.  (color online) Invariant-mass distributions of $\varXi _{cc}^{ + + }$ candidates (a) triggered by TOS and (b) triggered by exTIS, with fit results shown.

      The determination of the prompt $\varLambda _c^ +$ baryon yields, which are contaminated by $\varLambda _c^ +$ candidates produced in b-hadron decays, is done in two steps [44]. First, a binned extended maximum-likelihood fit to the $m(pK^-{\pi ^ + })$ invariant-mass distribution in the interval 2220-2360 ${\rm{MeV}}/{c^2}$ is performed to determine the total number of $\varLambda _c^ +$ candidates. Then a binned extended maximum-likelihood fit to the background-subtracted ${\log _{10}}\left( {\chi _{{\rm{IP}}}^2\left( {\varLambda _c^ + } \right)} \right)$ distribution is performed to separate the prompt $\varLambda _c^ +$ component from that originated in b-hadron decays. The mass distribution of $\varLambda _c^ +$ candidates is described by a sum of a Gaussian function and a modified Gaussian function with power-law tails on both sides with a common peak position. The background mass distribution is described by a first-order Chebyshev polynomial. The ${\log _{10}}\left( {\chi _{{\rm{IP}}}^2\left( {\varLambda _c^ + } \right)} \right)$ distribution, after subtracting the combinatorial background using the sPlot technique [45], is described by two Bukin functions [46]. All the parameters except the peak position and resolution of the functions are derived from a fit to simulated signal. Figs. 2 and 3 show the $p K^- {\pi ^ + }$ invariant-mass distribution and ${\log _{10}}\left( {\chi _{{\rm{IP}}}^2\left( {\varLambda _c^ + } \right)} \right)$ distributions in data together with the fit results for the two trigger categories. The signal yields for both the signal and the normalisation modes are presented in Table 1.

      Category$N_{\rm{sig}}$$N_{\rm{norm} } \;[10^{3}]$