| Records |
| Author |
Campanario, F.; Rauch, M.; Sapeta, S. |
| Title |
ZZ production at high transverse momenta beyond NLO QCD |
Type |
Journal Article |
| Year |
2015 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
| Volume |
08 |
Issue |
8 |
Pages |
070 - 25pp |
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| Abstract |
We study the production of the four-lepton final state l+l−l+l−, predominantly produced by a pair of electroweak Z bosons, ZZ. Using the LoopSim method, we merge NLO QCD results for ZZ and ZZ+jet and obtain approximate NNLO predictions for ZZ production. The exact gluon-fusion loop-squared contribution to the ZZ process is also included. On top of that, we add to our merged sample the gluon-fusion ZZ+jet contributions from the gluon-gluon channel, which is formally of N^3LO and provides approximate results at NLO for the gluon-fusion mechanism. The predictions are obtained with the VBFNLO package and include the leptonic decays of the Z bosons with all off-shell and spin-correlation effects, as well as virtual photon contributions. We compare our predictions with existing results for the total inclusive cross section at NNLO and find a very good agreement. Then, we present results for differential distributions for two experimental setups, one used in searches for anomalous triple gauge boson couplings, the other in Higgs analyses in the four charged-lepton final state channel. We find that the approximate NNLO corrections are large, reaching up to 20% at high transverse momentum of the Z boson or the leading lepton, and are not covered by the NLO scale uncertainties. Distributions of the four-lepton invariant mass are, however, stable with respect to QCD corrections at this order. |
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no |
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yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
2595 |
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ATLAS Collaboration (Aad, G. et al); Alvarez Piqueras, D.; Cabrera Urban, S.; Castillo Gimenez, V.; Costa, M.J.; Fernandez Martinez, P.; Ferrer, A.; Fiorini, L.; Fuster, J.; Garcia, C.; Garcia Navarro, J.E.; Gonzalez de la Hoz, S.; Hernandez Jimenez, Y.; Higon-Rodriguez, E.; Irles Quiles, A.; Jimenez Pena, J.; Kaci, M.; King, M.; Lacasta, C.; Lacuesta, V.R.; Marti-Garcia, S.; Mitsou, V.A.; Moles-Valls, R.; Oliver Garcia, E.; Pedraza Lopez, S.; Perez Garcia-Estañ, M.T.; Romero Adam, E.; Ros, E.; Salt, J.; Sanchez Martinez, V.; Soldevila, U.; Sanchez, J.; Torro Pastor, E.; Valero, A.; Valladolid Gallego, E.; Valls Ferrer, J.A.; Vos, M. |
| Title |
Analysis of events with b-jets and a pair of leptons of the same charge in pp collisions at p root s=8 TeV with the ATLAS detector |
Type |
Journal Article |
| Year |
2015 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
| Volume |
10 |
Issue |
10 |
Pages |
150 - 51pp |
| Keywords |
Exotics; Lepton production; Hadron-Hadron Scattering; Beyond Standard Model; vector-like quarks; four-top-production; chiral b'; same charge top pair |
| Abstract |
An analysis is presented of events containing jets including at least one b tagged jet, sizeable missing transverse momentum, and at least two leptons including a pair of the same electric charge, with the scalar sum of the jet and lepton transverse momenta being large. A data sample with an integrated luminosity of 20.3 fb(-1) of p p collisions at p root s = 8TeV recorded by the ATLAS detector at the Large Hadron Collider is used. Standard Model processes rarely produce these final states, but there are several models of physics beyond the Standard Model that predict an enhanced rate of production of such events; the ones considered here are production of vector-like quarks, enhanced fourtop- quark production, pair production of chiral b'-quarks, and production of two positively charged top quarks. Eleven signal regions are defined; subsets of these regions are combined when searching for each class of models. In the three signal regions primarily sensitive to positively charged top quark pair production, the data yield is consistent with the background expectation. There are more data events than expected from background in the set of eight signal regions defined for searching for vector-like quarks and chiral b'-quarks, but the significance of the discrepancy is less than two standard deviations. The discrepancy reaches 2.5 standard deviations in the set of five signal regions defined for searching for four-top-quark production. The results are used to set 95% CL limits on various models. |
| Address |
[Jackson, P.; Lee, L.; Soni, N.; White, M. J.] Univ Adelaide, Dept Phys, Adelaide, SA, Australia |
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Springer |
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English |
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1029-8479 |
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| Notes |
WOS:000373570900001 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
2615 |
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LHCb Collaboration (Aaij, R. et al); Martinez-Vidal, F.; Oyanguren, A.; Ruiz Valls, P.; Sanchez Mayordomo, C. |
| Title |
Measurements of prompt charm production cross-sections in pp collisions at root s=13 TeV |
Type |
Journal Article |
| Year |
2016 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
| Volume |
03 |
Issue |
3 |
Pages |
159 - 43pp |
| Keywords |
Charm physics; Forward physics; Hadron-Hadron scattering; Heavy quark production; QCD |
| Abstract |
Production cross-sections of prompt charm mesons are measured with the first data from pp collisions at the LHC at a centre-of-mass energy of 13 TeV. The data sample corresponds to an integrated luminosity of 4.98 +/- 0.19 pb(-1) collected by the LHCb experiment. The production cross-sections of D-0, D+, D (s) (+) , and D*+ mesons are measured in bins of charm meson transverse momentum, p(T), and rapidity, y, and cover the range 0 < p(T) < 15GeV/c and 2.0 < y < 4.5. The inclusive cross-sections for the four mesons, including charge conjugation, within the range of 1 < p(T) < 8 GeV/c are found to be sigma(pp -> D-0 X) = 2460 +/- 3 +/- 130 μb sigma(pp -> D+ X) = 1000 +/- 3 +/- 110 μb sigma(pp -> Ds+X) = 460 +/- 13 +/- 100 μb sigma(pp -> D*+ X) = 880 +/- 5 +/- 140 μb where the uncertainties are due to statistical and systematic uncertainties, respectively. |
| Address |
[Bediaga, I.; De Miranda, J. M.; Ferreira Rodrigues, F.; Gomes, A.; Massafferri, A.; Osorio Rodrigues, B.; dos Reis, A. C.; Rodrigues, A. B.] Ctr Brasileiro Pesquisas Fis, Rio De Janeiro, Brazil, Email: alex.pearce@cern.ch |
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Springer |
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English |
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1029-8479 |
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| Notes |
WOS:000373137700001 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
2606 |
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LHCb Collaboration (Aaij, R. et al); Martinez-Vidal, F.; Oyanguren, A.; Ruiz Valls, P.; Sanchez Mayordomo, C. |
| Title |
Study of psi(2S) production and cold nuclear matter effects in pPb collisions at root s(NN)=5 TeV |
Type |
Journal Article |
| Year |
2016 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
| Volume |
03 |
Issue |
3 |
Pages |
133 - 21pp |
| Keywords |
Particle and resonance production; Quarkonium; Relativistic heavy ion physics; Heavy Ion Experiments; Heavy-ion collision |
| Abstract |
The production of psi(2S) mesons is studied in dimuon final states using proton-lead (pPb) collision data collected by the LHCb detector. The data sample corresponds to an integrated luminosity of 1.6 nb(-1). The nucleon-nucleon centre-of-mass energy of the pPb collisions is root s(NN) = 5 TeV. The measurement is performed using psi(2S) mesons with transverse momentum less than 14 GeV/c and rapidity y in the ranges 1.5 < y < 4.0 and -5.0 < y < -2.5 in the nucleon-nucleon centre-of-mass system. The forward-backward production ratio and the nuclear modi fi cation factor are determined for psi(2S) mesons. Using the production cross-section results of psi(2S) and J/psi mesons from b-hadron decays, the b (b) over bar cross-section in pPb collisions at root s(NN) = 5 TeV is obtained. |
| Address |
[Bediaga, I.; De Miranda, J. M.; Ferreira Rodrigues, F.; Gomes, A.; Massafferri, A.; Osorio Rodrigues, B.; dos Reis, A. C.; Rodrigues, A. B.] CBPF, Rio De Janeiro, Brazil, Email: yangzhw@tsinghua.edu.cn |
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Springer |
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English |
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1029-8479 |
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| Notes |
WOS:000373110200001 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
2608 |
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| Author |
Bergstrom, J.; Gonzalez-Garcia, M.C.; Maltoni, M.; Pena-Garay, C.; Serenelli, A.M.; Song, N.Q. |
| Title |
Updated determination of the solar neutrino fluxes from solar neutrino data |
Type |
Journal Article |
| Year |
2016 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
| Volume |
03 |
Issue |
3 |
Pages |
132 - 19pp |
| Keywords |
Neutrino Physics; Solar and Atmospheric Neutrinos |
| Abstract |
We present an update of the determination of the solar neutrino fluxes from a global analysis of the solar and terrestrial neutrino data in the framework of three-neutrino mixing. Using a Bayesian analysis we reconstruct the posterior probability distribution function for the eight normalization parameters of the solar neutrino fluxes plus the relevant masses and mixing, with and without imposing the luminosity constraint. We then use these results to compare the description provided by different Standard Solar Models. Our results show that, at present, both models with low and high metallicity can describe the data with equivalent statistical agreement. We also argue that even with the present experimental precision the solar neutrino data have the potential to improve the accuracy of the solar model predictions. |
| Address |
[Bergstroem, Johannes; Gonzalez-Garcia, M. C.] Univ Barcelona, Dept Estruct & Constituents Mat, Diagonal 647, E-08028 Barcelona, Spain, Email: bergstrom@ecm.ub.edu; |
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Springer |
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English |
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1029-8479 |
ISBN |
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Conference |
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| Notes |
WOS:000373050700004 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
2609 |
| Permanent link to this record |
