Updated determination of $D^0$-$\overline{D}{}^0$ mixing and CP violation parameters with $D^0\to K^+\pi^-$ decays

(2017)

Authors:

LHCb collaboration, R Aaij, B Adeva, M Adinolfi, Z Ajaltouni, S Akar, J Albrecht, F Alessio, M Alexander, A Alfonso Albero, S Ali, G Alkhazov, P Alvarez Cartelle, AA Alves, S Amato, S Amerio, Y Amhis, L An, L Anderlini, G Andreassi, M Andreotti, JE Andrews, RB Appleby, F Archilli, P d'Argent, J Arnau Romeu, A Artamonov, M Artuso, E Aslanides, M Atzeni, G Auriemma, M Baalouch, I Babuschkin, S Bachmann, JJ Back, A Badalov, C Baesso, S Baker, V Balagura, W Baldini, A Baranov, RJ Barlow, C Barschel, S Barsuk, W Barter, F Baryshnikov, V Batozskaya, V Battista, A Bay, L Beaucourt, J Beddow, F Bedeschi, I Bediaga, A Beiter, LJ Bel, N Beliy, V Bellee, N Belloli, K Belous, I Belyaev, E Ben-Haim, G Bencivenni, S Benson, S Beranek, A Berezhnoy, R Bernet, D Berninghoff, E Bertholet, A Bertolin, C Betancourt, F Betti, MO Bettler, M van Beuzekom, Ia Bezshyiko, S Bifani, P Billoir, A Birnkraut, A Bizzeti, M Bjørn, T Blake, F Blanc, S Blusk, V Bocci, T Boettcher, A Bondar, N Bondar, I Bordyuzhin, S Borghi, M Borisyak, M Borsato, F Bossu, M Boubdir, TJV Bowcock, E Bowen, C Bozzi, S Braun, J Brodzicka, D Brundu, E Buchanan, C Burr, A Bursche, J Buytaert, W Byczynski, S Cadeddu, H Cai, R Calabrese, R Calladine, M Calvi, M Calvo Gomez, A Camboni, P Campana, DH Campora Perez, L Capriotti, A Carbone, G Carboni, R Cardinale, A Cardini, P Carniti, L Carson, K Carvalho Akiba, G Casse, L Cassina, M Cattaneo, G Cavallero, R Cenci, D Chamont, MG Chapman, M Charles, Ph Charpentier, G Chatzikonstantinidis, M Chefdeville, S Chen, SF Cheung, S-G Chitic, V Chobanova, M Chrzaszcz, A Chubykin, P Ciambrone, X Cid Vidal, G Ciezarek, PEL Clarke, M Clemencic, HV Cliff, J Closier, V Coco, J Cogan, E Cogneras, V Cogoni, L Cojocariu, P Collins, T Colombo, A Comerma-Montells, A Contu, G Coombs, S Coquereau, G Corti, M Corvo, CM Costa Sobral, B Couturier, GA Cowan, DC Craik, A Crocombe, M Cruz Torres, R Currie, C D'Ambrosio, F Da Cunha Marinho, CL Da Silva, E Dall'Occo, J Dalseno, A Davis, O De Aguiar Francisco, K De Bruyn, S De Capua, M De Cian, JM De Miranda, L De Paula, M De Serio, P De Simone, CT Dean, D Decamp, L Del Buono, H-P Dembinski, M Demmer, A Dendek, D Derkach, O Deschamps, F Dettori, B Dey, A Di Canto, P Di Nezza, H Dijkstra, F Dordei, M Dorigo, A Dosil Suárez, L Douglas, A Dovbnya, K Dreimanis, L Dufour, G Dujany, P Durante, JM Durham, D Dutta, R Dzhelyadin, M Dziewiecki, A Dziurda, A Dzyuba, S Easo, M Ebert, U Egede, V Egorychev, S Eidelman, S Eisenhardt, U Eitschberger, R Ekelhof, L Eklund, S Ely, S Esen, HM Evans, T Evans, A Falabella, N Farley, S Farry, D Fazzini, L Federici, D Ferguson, G Fernandez, P Fernandez Declara, A Fernandez Prieto, F Ferrari, L Ferreira Lopes, F Ferreira Rodrigues, M Ferro-Luzzi, S Filippov, RA Fini, M Fiorini, M Firlej, C Fitzpatrick, T Fiutowski, F Fleuret, M Fontana, F Fontanelli, R Forty, V Franco Lima, M Frank, C Frei, J Fu, W Funk, E Furfaro, C Färber, E Gabriel, A Gallas Torreira, D Galli, S Gallorini, S Gambetta, M Gandelman, P Gandini, Y Gao, LM Garcia Martin, J García Pardiñas, J Garra Tico, L Garrido, D Gascon, C Gaspar, L Gavardi, G Gazzoni, D Gerick, E Gersabeck, M Gersabeck, T Gershon, Ph Ghez, S Gianì, V Gibson, OG Girard, L Giubega, K Gizdov, VV Gligorov, D Golubkov, A Golutvin, A Gomes, IV Gorelov, C Gotti, E Govorkova, JP Grabowski, R Graciani Diaz, LA Granado Cardoso, E Graugés, E Graverini, G Graziani, A Grecu, R Greim, P Griffith, L Grillo, L Gruber, BR Gruberg Cazon, O Grünberg, E Gushchin, Yu Guz, T Gys, C Göbel, T Hadavizadeh, C Hadjivasiliou, G Haefeli, C Haen, SC Haines, B Hamilton, X Han, TH Hancock, S Hansmann-Menzemer, N Harnew, ST Harnew, C Hasse, M Hatch, J He, M Hecker, K Heinicke, A Heister, K Hennessy, P Henrard, L Henry, E van Herwijnen, M Heß, A Hicheur, D Hill, PH Hopchev, W Hu, W Huang, ZC Huard, W Hulsbergen, T Humair, M Hushchyn, D Hutchcroft, P Ibis, M Idzik, P Ilten, R Jacobsson, J Jalocha, E Jans, A Jawahery, F Jiang, M John, D Johnson, CR Jones, C Joram, B Jost, N Jurik, S Kandybei, M Karacson, JM Kariuki, S Karodia, N Kazeev, M Kecke, F Keizer, M Kelsey, M Kenzie, T Ketel, E Khairullin, B Khanji, C Khurewathanakul, T Kirn, S Klaver, K Klimaszewski, T Klimkovich, S Koliiev, M Kolpin, R Kopecna, P Koppenburg, A Kosmyntseva, S Kotriakhova, M Kozeiha, L Kravchuk, M Kreps, F Kress, P Krokovny, W Krzemien, W Kucewicz, M Kucharczyk, V Kudryavtsev, AK Kuonen, T Kvaratskheliya, D Lacarrere, G Lafferty, A Lai, G Lanfranchi, C Langenbruch, T Latham, C Lazzeroni, R Le Gac, A Leflat, J Lefrançois, R Lefèvre, F Lemaitre, E Lemos Cid, O Leroy, T Lesiak, B Leverington, P-R Li, T Li, Y Li, Z Li, X Liang, T Likhomanenko, R Lindner, F Lionetto, V Lisovskyi, X Liu, D Loh, A Loi, I Longstaff, JH Lopes, D Lucchesi, M Lucio Martinez, H Luo, A Lupato, E Luppi, O Lupton, A Lusiani, X Lyu, F Machefert, F Maciuc, V Macko, P Mackowiak, S Maddrell-Mander, O Maev, K Maguire, D Maisuzenko, MW Majewski, S Malde, B Malecki, A Malinin, T Maltsev, G Manca, G Mancinelli, D Marangotto, J Maratas, JF Marchand, U Marconi, C Marin Benito, M Marinangeli, P Marino, J Marks, G Martellotti, M Martin, M Martinelli, D Martinez Santos, F Martinez Vidal, A Massafferri, R Matev, A Mathad, Z Mathe, C Matteuzzi, A Mauri, E Maurice, B Maurin, A Mazurov, M McCann, A McNab, R McNulty, JV Mead, B Meadows, C Meaux, F Meier, N Meinert, D Melnychuk, M Merk, A Merli, E Michielin, DA Milanes, E Millard, M-N Minard, L Minzoni, DS Mitzel, A Mogini, J Molina Rodriguez, T Mombächer, IA Monroy, S Monteil, M Morandin, MJ Morello, O Morgunova, J Moron, AB Morris, R Mountain, F Muheim, M Mulder, D Müller, J Müller, K Müller, V Müller, P Naik, T Nakada, R Nandakumar, A Nandi, I Nasteva, M Needham, N Neri, S Neubert, N Neufeld, M Neuner, TD Nguyen, C Nguyen-Mau, S Nieswand, R Niet, N Nikitin, T Nikodem, A Nogay, DP O'Hanlon, A Oblakowska-Mucha, V Obraztsov, S Ogilvy, R Oldeman, CJG Onderwater, A Ossowska, JM Otalora Goicochea, P Owen, A Oyanguren, PR Pais, A Palano, M Palutan, A Papanestis, M Pappagallo, LL Pappalardo, W Parker, C Parkes, G Passaleva, A Pastore, M Patel, C Patrignani, A Pearce, A Pellegrino, G Penso, M Pepe Altarelli, S Perazzini, D Pereima, P Perret, L Pescatore, K Petridis, A Petrolini, A Petrov, M Petruzzo, E Picatoste Olloqui, B Pietrzyk, G Pietrzyk, M Pikies, D Pinci, F Pisani, A Pistone, A Piucci, V Placinta, S Playfer, M Plo Casasus, F Polci, M Poli Lener, A Poluektov, I Polyakov, E Polycarpo, GJ Pomery, S Ponce, A Popov, D Popov, S Poslavskii, C Potterat, E Price, J Prisciandaro, C Prouve, V Pugatch, A Puig Navarro, H Pullen, G Punzi, W Qian, J Qin, R Quagliani, B Quintana, B Rachwal, JH Rademacker, M Rama, M Ramos Pernas, MS Rangel, I Raniuk, F Ratnikov, G Raven, M Ravonel Salzgeber, M Reboud, F Redi, S Reichert, AC dos Reis, C Remon Alepuz, V Renaudin, S Ricciardi, S Richards, M Rihl, K Rinnert, P Robbe, A Robert, AB Rodrigues, E Rodrigues, JA Rodriguez Lopez, A Rogozhnikov, S Roiser, A Rollings, V Romanovskiy, A Romero Vidal, M Rotondo, MS Rudolph, T Ruf, P Ruiz Valls, J Ruiz Vidal, JJ Saborido Silva, E Sadykhov, N Sagidova, B Saitta, V Salustino Guimaraes, C Sanchez Mayordomo, B Sanmartin Sedes, R Santacesaria, C Santamarina Rios, M Santimaria, E Santovetti, G Sarpis, A Sarti, C Satriano, A Satta, DM Saunders, D Savrina, S Schael, M Schellenberg, M Schiller, H Schindler, M Schmelling, T Schmelzer, B Schmidt, O Schneider, A Schopper, HF Schreiner, M Schubiger, MH Schune, R Schwemmer, B Sciascia, A Sciubba, A Semennikov, ES Sepulveda, A Sergi, N Serra, J Serrano, L Sestini, P Seyfert, M Shapkin, I Shapoval, Y Shcheglov, T Shears, L Shekhtman, V Shevchenko, BG Siddi, R Silva Coutinho, L Silva de Oliveira, G Simi, S Simone, M Sirendi, N Skidmore, T Skwarnicki, IT Smith, J Smith, M Smith, L Soares Lavra, MD Sokoloff, FJP Soler, B Souza De Paula, B Spaan, P Spradlin, S Sridharan, F Stagni, M Stahl, S Stahl, P Stefko, S Stefkova, O Steinkamp, S Stemmle, O Stenyakin, M Stepanova, H Stevens, S Stone, B Storaci, S Stracka, ME Stramaglia, M Straticiuc, U Straumann, J Sun, L Sun, K Swientek, V Syropoulos, T Szumlak, M Szymanski, S T'Jampens, A Tayduganov, T Tekampe, G Tellarini, F Teubert, E Thomas, J van Tilburg, MJ Tilley, V Tisserand, M Tobin, S Tolk, L Tomassetti, D Tonelli, R Tourinho Jadallah Aoude, E Tournefier, M Traill, MT Tran, M Tresch, A Trisovic, A Tsaregorodtsev, P Tsopelas, A Tully, N Tuning, A Ukleja, A Usachov, A Ustyuzhanin, U Uwer, C Vacca, A Vagner, V Vagnoni, A Valassi, S Valat, G Valenti, R Vazquez Gomez, P Vazquez Regueiro, S Vecchi, M van Veghel, JJ Velthuis, M Veltri, G Veneziano, A Venkateswaran, TA Verlage, M Vernet, M Veronesi, M Vesterinen, JV Viana Barbosa, D Vieira, M Vieites Diaz, H Viemann, X Vilasis-Cardona, M Vitti, V Volkov, A Vollhardt, B Voneki, A Vorobyev, V Vorobyev, C Voß, JA de Vries, C Vázquez Sierra, R Waldi, J Walsh, J Wang, Y Wang, DR Ward, HM Wark, NK Watson, D Websdale, A Weiden, C Weisser, M Whitehead, J Wicht, G Wilkinson, M Wilkinson, M Williams, M Williams, T Williams, FF Wilson, J Wimberley, M Winn, J Wishahi, W Wislicki, M Witek, G Wormser, SA Wotton, K Wyllie, Y Xie, M Xu, Q Xu, Z Xu, Z Xu, Z Yang, Z Yang, Y Yao, H Yin, J Yu, X Yuan, O Yushchenko, KA Zarebski, M Zavertyaev, L Zhang, Y Zhang, A Zhelezov, Y Zheng, X Zhu, V Zhukov, JB Zonneveld, S Zucchelli

First observation of forward Z→bb¯ production in pp collisions at s√=8 TeV

Physics Letters B Elsevier 776 (2017) 430-439

Authors:

Mikkel Bjørn, SF Cheung, Thomas Evans, Paolo Gandini, Barak R Gruberg Cazon, Thomas Hadavizadeh, Thomas H Hancock, Neville Harnew, Donal Hill, Pawel G Jalocha, Malcolm JJ John, Nathan P Jurik, Sneha Malde, Anita K Nandi, Hannah L Pullen, Alexandra Rollings, G Veneziano, Mika Vesterinen, Guy R Wilkinson

Abstract:

The decay Z→bb¯ is reconstructed in pp collision data, corresponding to 2 fb −1 of integrated luminosity, collected by the LHCb experiment at a centre-of-mass energy of s=8 TeV. The product of the Z production cross-section and the Z→bb¯ branching fraction is measured for candidates in the fiducial region defined by two particle-level b-quark jets with pseudorapidities in the range 2.2 < η < 4.2, with transverse momenta p T > 20 GeV and dijet invariant mass in the range 45 < m jj < 165 GeV. From a signal yield of 5462±763 Z→bb¯ events, where the uncertainty is statistical, a production cross-section times branching fraction of 332±46±59 pb is obtained, where the first uncertainty is statistical and the second systematic. The measured significance of the signal yield is 6.0 standard deviations. This measurement represents the first observation of the Z→bb¯ production in the forward region of pp collisions.

Measurement of CP observables in B-+/- -> D(*)K-+/- and B-+/- -> D(*)pi(+/-) decays

Physical Letters B Elsevier 777 (2017) 16-30

Authors:

R Aaij, B Adeva, M Adinolfi, M Bjørn, SF Cheung, T Evans, P Gandini, BRG Cazon, T Hadavizadeh, TH Hancock, Neville Harnew, D Hill, J Jalocha, M John, N Jurik, S Malde, A Nandi, H Pullen, A Rollings, G Veneziano, M Vesterinen, G Wilkinson

Abstract:

Measurements of CP observables in B ± →D (⁎) K ± and B ± →D (⁎) π ± decays are presented, where D (⁎) indicates a neutral D or D ⁎ meson that is an admixture of D (⁎)0 and D¯ (⁎)0 states. Decays of the D ⁎ meson to the Dπ 0 and Dγ final states are partially reconstructed without inclusion of the neutral pion or photon, resulting in distinctive shapes in the B candidate invariant mass distribution. Decays of the D meson are fully reconstructed in the K ± π ∓ , K + K − and π + π − final states. The analysis uses a sample of charged B mesons produced in pp collisions collected by the LHCb experiment, corresponding to an integrated luminosity of 2.0, 1.0 and 2.0 fb −1 taken at centre-of-mass energies of s=7, 8 and 13 TeV, respectively. The study of B ± →D ⁎ K ± and B ± →D ⁎ π ± decays using a partial reconstruction method is the first of its kind, while the measurement of B ± →DK ± and B ± →Dπ ± decays is an update of previous LHCb measurements. The B ± →DK ± results are the most precise to date.

Bose-Einstein correlations of same-sign charged pions in the forward region in pp collisions at root s=7 TeV

Journal of High Energy Physics Springer 2017:12 (2017) 025

Authors:

R Aaij, B Adeva, M Adinolfi, Mikkel Bjørn, Thomas Evans, Paolo Gandini, Barak R Gruberg Cazon, Thomas Hadavizadeh, Thomas H Hancock, Neville Harnew, Donal Hill, Pawel G Jalocha, Malcolm JJ John, Nathan P Jurik, Sneha Malde, Anita K Nandi, Hannah L Pullen, Alexandra Rollings, Mika Vesterinen, Guy R Wilkinson

Abstract:

Bose-Einstein correlations of same-sign charged pions, produced in proton-proton collisions at a 7 TeV centre-of-mass energy, are studied using a data sample collected by the LHCb experiment. The signature for Bose-Einstein correlations is observed in the form of an enhancement of pairs of like-sign charged pions with small four-momentum difference squared. The charged-particle multiplicity dependence of the Bose-Einstein correlation parameters describing the correlation strength and the size of the emitting source is investigated, determining both the correlation radius and the chaoticity parameter. The measured correlation radius is found to increase as a function of increasing charged-particle multiplicity, while the chaoticity parameter is seen to decrease.

First observation of the rare purely baryonic decay B0 → pp¯

Physical Review Letters American Physical Society 119:23 (2017) 232001

Authors:

R Aaij, B Adeva, M Adinolfi, Mikkel Bjørn, Thomas Evans, Paolo Gandini, Barak R Gruberg Cazon, Thomas Hadavizadeh, Thomas H Hancock, Neville Harnew, Donal Hill, Pawel G Jalocha, Malcolm JJ John, Nathan P Jurik, Sneha Malde, Anita K Nandi, Hannah L Pullen, Alexandra Rollings, Mika Vesterinen, Guy R Wilkinson

Abstract:

The first observation of the decay of a B0 meson to a purely baryonic final state, B0→pp¯ , is reported. The proton-proton collision data sample used was collected with the LHCb experiment at center-of-mass energies of 7 and 8 TeV and corresponds to an integrated luminosity of 3.0 fb^−1. The branching fraction is determined to be B(B0→pp¯)=(1.25±0.27±0.18)×10^−8, where the first uncertainty is statistical and the second systematic. The decay mode B0→pp¯ is the rarest decay of the B0 meson observed to date. The decay B0s→pp¯ is also investigated. No signal is seen and the upper limit B(B0s→pp¯)<1.5×10^−8 at 90% confidence level is set on the branching fraction.