Measurement of the Λb polarization in Z decays

Buskulic, D.; Casper, D.; Bonis, I. De; Décamp, D.; Ghez, Ph.; Goy, C.; Lees, J. P.; Lucotte, A.; Minard, M.-N.; Odier, P.; Pietrzyk, B.; Chmeissani, M.; Crespo, J.M.; Efthymiopoulos, I.; Fernández, E.; Fernández-Bosman, M.; Garrido, L.; Rozas, A. Juste; Martı́nez, M.; Orteu, S.; Pacheco, A.; Aranda, C. Padilla; Palla, F.; Pascual, Á.; Perlas, J. A.; Riu, I.; Sánchez, F.; Teubert, F.; Colaleo, A.; Creanza, D.; Palma, M. De; Farilla, A.; Gelao, G.; Girone, M.; Iaselli, G.; Mäggi, G.; Maggi, M.; Marinelli, N.; Natali, S.; Nuzzo, S.; Ranieri, A.; Raso, G.; Romanò, F.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Zito, G.; Huang, X. T.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Alemany, R.; Bazarko, A.O.; Bonvicini, G.; Cattaneo, M.; Comas, P.; Coyle, P.; Drevermann, H.; Forty, R.; Frank, M.; Hagelberg, R.; Harvey, J.; Jacobsen, R.G.; Janot, P.; Jost, B.; Kneringer, E.; Knobloch, J.; Lehraus, I.; Martin, E. B.; Mató, P.; Minten, A.; Miquel, R.; Mir, L. M.; Moneta, L.; Oest, T.; Palazzi, P.; Pater, J. R.; Pusztaszeri, J. F.; Ranjard, F.; Rensing, P.; Rolandi, G.; Schlatter, D.; Schmelling, M.; Schneider, O.; Tejessy, W.; Tomalin, I. R.; Venturi, A.; Wachsmuth, H.; Wildish, T.; Witzeling, W.; Wotschack, J.; Ajaltouni, Z.; Bardadin-Otwinowska, M.; Barrès, A.; Boyer, C.; Falvard, A.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Monteil, S.; Montret, J. C.; Pallin, D.; Perret, P.; Podlyski, F.; Proriol, J.; Rossignol, J. M.; Saadi, F.; Fearnley, T.; Hansen, J. B.; Hansen, J. R.; Hansen, P. H.; Nilsson, B.S.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Siotis, I.; Vayaki, A.; Zachariadou, K.; Blondel, A.; Bonneaud, G. R.; Brient, J. C.; Bourdon, P.; Rougé, A.; Rumpf, M.; Tanaka, R.; Valassi, A.; Verderi, M.; Videau, H.; Candlin, D. J.; Parsons, M. I.; Focardi, E.; Parrini, G.; Corden, M.; Delfino, M.; Georgiopoulos, C.; Jaffe, D. E.; Antonelli, A.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Chiarella, V.; Felici, G.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, F.; Passalacqua, L.; Pepe-Altarelli, M.; Curtis, L.; Dorris, S. J.; Halley, A.W.; Knowles, I. G.; Lynch, J.G.; O’Shea, V.; Raine, C.; Reeves, P.; Scarr, J. M.; Smith, K. M.; Thompson, A. S.; Thomson, F.; Thorn, S.; Turnbul, R. M.; Becker, U.; Braun, O.; Geweniger, C.; Graefe, G.; Hanke, P.; Hepp, V.; Kluge, E.-E.; Putzer, A.; Rensch, B.; Schmidt, M.; Sommer, J.; Stenzel, H.; Tittel, K.; Werner, S.; Wunsch, M.; Abbaneo, D.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Colling, D.; Dornan, RJ; Konstantinidis, N.; Moutoussi, A.; Nash, J.; Martin, G.; Sedgbeer, J. K.; Stacey, A. M.; Dissertori, G.; Girtler, P.; Kühn, D.; Rudolph, G.; Bowdery, C. K.; Brodbeck, T. J.; Colrain, P.; Crawford, G.; Finch, A. J.; Foster, F.; Hughes, G.; Sloan, T.; Whelan, E. P.; Williams, M.I.; Galla, A.; Greene, A. M.; Kleinknecht, K.; Quast, G.; Raab, J.; Renk, B.; Sander, H. G.; Wanke, R.; Gemmeren, P. van; Zeitnitz, C.; Aubert, J.J.; Bencheikh, A. M.; Benchouk, C.; Bonissent, A.; Bujosa, G.; Calvet, D.; Carr, J.; Diaconu, C.; Etienne, F.; Thulasidas, M.; Nicod, D.; Payre, P.; Rousseau, D.; Talby, M.; Abt, I.; Assmann, R.; Bauer, C.; Blum, W.; Brown, D. N.; Dietl, H.; Dydak, F.; Ganis, G.; Gotzhein, C.; Jakobs, K.; Kroha, H.; Lütjens, G.; Lütz, G.; Männer, W.; Moser, H. G.; Richter, R.; Rosado-Schlosser, A.; Schael, S.; Settles, R.; Seywerd, H.; Denis, R. St.; Wiedenmann, W.; Wolf, G.; Boucrot, J.; Callot, O.; Cordier, A.; Courault, F.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, P.; Jacquet, M.; Kim, D. W.; Diberder, F. Le; Lefrançois, J.; Lutz, A.M.; Nikolić, Irena; Park, H. J.; Park, I. C.; Schune, M. H.; Simion, S.; Veillet, J. J.; Videau, I.; Azzurri, P.; Bagliesi, G.; Batignani, G.; Bettarini, S.; Bozzi, C.; Calderini, G.; Capinelli, M.; Ciocci, M. A.; Ciulli, V.; Dell’Orso, R.; Fantechi, R.; Ferrante, I.; Foà, L.; Forti, F.; Giassi, A.; Giorgi, M. A.; Gregorio, A.; Ligabue, F.; Lusiani, A.; Marrocchesi, P. S.; Messineo, A.; Rizzo, G.; Sanguinetti, G.; Sciabà, A.; Spagnolo, P.; Steinberger, J.; Тенчини, Р.; Tonelli, G.; Vannini, C.; Verdini, P. G.; Walsh, J.; Betteridge, A. P.; Blair, G.A.; Bryant, L. M.; Green, M. G.; Johnson, D.; Medcalf, T.; Perrodo, P.; Strong, J. A.; Wimmersperg-Toeller, J. H. von; Botterill, D.; Clifft, R. W.; Edgecock, R.; Haywood, S. J.; Edwards, M.; Maley, P.; Norton, P. R.; Thompson, J.C.; Bloch-Devaux, B.; Colas, P.; Emery, S.; Kozanecki, W.; Lançon, E.; Lemaire, M. C.; Locci, E.; Marx, B.; Pérez, P.; Rander, J.; Renardy, J. F.; Roussarie, A.; Schuller, J. P.; Schwindling, J.; Trabelsi, A.; Vallage, B.; Johnson, R.P.; Kim, H. Y.; Litke, A. M.; McNeil, M.A.; Taylor, G. N.; Beddall, A. J.; Booth, C. N.; Boswell, Rod; Brew, C.; Cartwright, S. L.; Combley, F.; Koksal, A.; Letho, M.; Newton, W. M.; Rankin, C.; Reeve, J.; Thompson, L.F.; Böhrer, A.; Brandt, Siegmund; Cowan, G.; Feigl, Eric O.; Grupen, C.; Lutters, G.; Minguet-Rodriguez, J.; Rivera, F.; Saraiva, Pedro; Smolík, L.; Stephan, F.; Apollonio, M.; Bosisio, L.; Marina, R. Delia; Giannini, G.; Gobbo, B.; Musolino, G.; Ragusa, F.; Rothberg, J.; Wasserbaech, S.; Armstronga, S. R.; Bellantoni, L.; Elmer, P.; Feng, Z.; Ferguson, D.P.S.; Gao, Y. S.; González, S.; Grahl, J.; Greening, T.C.; Harton, J. L.; Hayes, O.J.; Hu, H.; McNamara, P.A.; Nachtman, J. M.; Orejudos, W.; Pan, Y.; Saadi, Y.; Schmitt, M.; Scott, I.; Sharma, V.; Turk, J. D.; Walsh, A. M.; Wu, Lan; Wu, X.; Yamartino, J. M.; Zheng, M.; Zobernig, G.

doi:10.1016/0370-2693(95)01433-0

Cited by 59 publications

(59 citation statements)

References 23 publications

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“…(2.12), all a priori unknown non-perturbative contributions associated with the fragmentation function are contained in D np q→γ (x, µ 0 ) which has to be determined from the data. This non-perturbative input has been extracted from the ALEPH 'photon' + 1 jet data [1] for y cut = 0.06 and z > 0.7. At lowest order, we have [1],…”

Section: Inclusive Photon Production In the Fixed Order Approachmentioning

confidence: 99%

“…These events were defined by the application of the Durham jet clustering algorithm [4] to both hadronic and electromagnetic clusters. A comparison between the observed rate and the O(α) [1,5] or O(αα s ) [6] theoretical estimates yielded a first determination of the quark-to-photon fragmentation function accurate at leading and next-to-leading order. The theoretical basis on which the measurement of the 'photon' + 1 jet rate relies, is an explicit counting of powers of the strong coupling α s in both the direct and the fragmentation contributions, and where no resummation of ln µ 2 F is performed.…”

Section: Introductionmentioning

confidence: 99%

“…The most promising environment for a determination of the quark-to-photon fragmentation function D q→γ (x, µ F ) is the study of photon production in electron-positron annihilation into hadrons. Such measurements have been recently presented by the ALEPH [1] and OPAL [2] collaborations at CERN. Both measurements differ not only in the experimental observable studied to determine the quark-to-photon fragmentation function, but also in the theoretical framework used to match direct and fragmentation contributions onto each other.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Final state photon production at LEP

Ridder¹,

Glover

1999

Eur. Phys. J. C

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We present a detailed study of photon production in hadronic events in electronpositron annihilation at LEP energies. We show that estimates of the inclusive photon spectrum using the quark-to-photon fragmentation function determined using the ALEPH 'photon' + 1 jet data agree well with the observations of the OPAL collaboration. This agreement shows that the photon fragmentation function determined in this way can be used for inclusive observables. We also compare next-to-leading order and beyond leading logarithm predictions obtained using the numerically resummed solutions of the fragmentation function evolution equation of Bourhis, Fontannaz and Guillet and Glück, Reya and Vogt with the data. Moreover, in order to check the general behaviour of the fragmentation function, we consider an analytic series expansion in the strong coupling. We find that the parameterizations are inaccurate at large x values. While the OPAL data is in broad agreement with estimates based on any of these approaches, the ALEPH data prefers the resummed BFG parameterization. Finally, there is some ambiguity as to whether the fragmentation function is treated as O(α) or O(α/α s ). We show that at present this ambiguity affects mainly the prediction for the 'photon' + 1 jet rate at large z.

show abstract

Section: Inclusive Photon Production In the Fixed Order Approachmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Final state photon production at LEP

Ridder¹,

Glover

1999

Eur. Phys. J. C

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show abstract

“…However, it is shown in [46] that additional requirements on a muon from the b-jet is capable of improving both the tagging and the tagging-overmistag efficiencies for b-quarks up to intermediate jet p T while no information is available for very energetic jets. Regarding the b-hadron helicity, there is no result currently available at the LHC, thus we take the values available from LEP [18,19], quantifiable in an overall 10% efficiency, as an estimate to quantitatively discuss spin observables. By considering this extra efficiency factor, we are in fact also further selecting b-jets with prompt hard leptons.…”

Section: Efficiencies and Uncertaintiesmentioning

confidence: 99%

“…If the b-quark hadronises before decaying, it has also been shown that its spin informations can be transmitted to b-hadrons (e.g., Λ b ), albeit with some dilution factors [18]. Then, the semi-leptonic decays of the latter would enable spin measurements, as pioneered at LEP [19]. It is not clear however if the same measurement is possible at the LHC, due to the higher boost of the emerging lepton and the narrower b-jet cone.…”

Section: Introductionmentioning

confidence: 99%

Non-exotic Z′ signals in ℓ + ℓ −, $ b\overline{b} $ and $ t\overline{t} $ final states at the LHC

Basso

Mimasu

Moretti

2012

J. High Energ. Phys.

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In the attempt to fully profile a Z boson accessible at the Large Hadron Collider (LHC), we study the sensitivity of di-lepton (for the electron, muon and tauon cases) and di-quark (for the case of the heavy flavours, t and, possibly, b) samples to the nature of the new gauge state, for a one-dimensional class of non-exotic Z bosons. Assuming realistic final state reconstruction efficiencies and error estimates, we find that, depending on the CERN collider energy and luminosity, the best chances of extracting the Z quantum numbers occur when two or more of these channels are simultaneously explored, as none of them separately enables one to fully probe the parameter spaces of the aforementioned models. Effects of Standard Model (SM) background as well interferences between this and the various Z signals have been accounted for. A complete study of cross sections and asymmetries (both spatial and spin ones) makes clear the need for complementarity, especially for their disentanglement over the full parameter space.

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Measurement of the $$ {\Lambda}_b^0 $$→ J/ψΛ angular distribution and the $$ {\Lambda}_b^0 $$ polarisation in pp collisions

Aaij¹,

Beteta²,

Ackernley³

et al. 2020

J. High Energ. Phys.

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This paper presents an analysis of the Λ 0 b → J/ψΛ angular distribution and the transverse production polarisation of Λ 0 b baryons in proton-proton collisions at centreof-mass energies of 7, 8 and 13 TeV. The measurements are performed using data corresponding to an integrated luminosity of 4.9 fb −1 , collected with the LHCb experiment. The polarisation is determined in a fiducial region of Λ 0 b transverse momentum and pseudorapidity of 1 < p T < 20 GeV/c and 2 < η < 5, respectively. The data are consistent with Λ 0 b baryons being produced unpolarised in this region. The parity-violating asymmetry parameter of the Λ → pπ − decay is also determined from the data and its value is found to be consistent with a recent measurement by the BES III collaboration.

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Measurement of the Λb polarization in Z decays

Cited by 59 publications

References 23 publications

Final state photon production at LEP

Final state photon production at LEP

Non-exotic Z′ signals in ℓ + ℓ −, $ b\overline{b} $ and $ t\overline{t} $ final states at the LHC

Measurement of the $$ {\Lambda}_b^0 $$→ J/ψΛ angular distribution and the $$ {\Lambda}_b^0 $$ polarisation in pp collisions

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