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Author |
ATLAS Collaboration (Aad, G. et al); Amoros, G.; Cabrera Urban, S.; Castillo Gimenez, V.; Costa, M.J.; Escobar, C.; Ferrer, A.; Fuster, J.; Garcia, C.; Gonzalez de la Hoz, S.; Hernandez Jimenez, Y.; Higon-Rodriguez, E.; Irles Quiles, A.; Kaci, M.; Lacasta, C.; Lacuesta, V.R.; Marti-Garcia, S.; Miñano, M.; Mitsou, V.A.; Moles-Valls, R.; Moreno Llacer, M.; Oliver Garcia, E.; Perez Garcia-Estañ, M.T.; Ros, E.; Salt, J.; Solans, C.A.; Soldevila, U.; Sanchez, J.; Torro Pastor, E.; Valladolid Gallego, E.; Valls Ferrer, J.A.; Villaplana Perez, M.; Vos, M.; Wildauer, A. |
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Title |
Observation of a Centrality-Dependent Dijet Asymmetry in Lead-Lead Collisions at root s(NN)=2.76 TeV with the ATLAS Detector at the LHC |
Type |
Journal Article |
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Year |
2010 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
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Volume |
105 |
Issue |
25 |
Pages |
252303 - 18pp |
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Keywords |
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Abstract |
By using the ATLAS detector, observations have been made of a centrality-dependent dijet asymmetry in the collisions of lead ions at the Large Hadron Collider. In a sample of lead-lead events with a per-nucleon center of mass energy of 2.76 TeV, selected with a minimum bias trigger, jets are reconstructed in fine-grained, longitudinally segmented electromagnetic and hadronic calorimeters. The transverse energies of dijets in opposite hemispheres are observed to become systematically more unbalanced with increasing event centrality leading to a large number of events which contain highly asymmetric dijets. This is the first observation of an enhancement of events with such large dijet asymmetries, not observed in proton-proton collisions, which may point to an interpretation in terms of strong jet energy loss in a hot, dense medium. |
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Address |
[Aad, G.; Ahles, F.; Beckingham, M.; Bernhard, R.; Bitenc, U.; Bruneliere, R.; Caron, S.; Carpentieri, C.; Christov, A.; Dahlhoff, A.; Dietrich, J.; Eckert, S.; Fehling-Kaschek, M.; Flechl, M.; Glatzer, J.; Hartert, J.; Herten, G.; Horner, S.; Jakobs, K.; Ketterer, C.; Koetsveld, F.; Kollefrath, M.; Kononov, A. I.; Kuehn, S.; Lai, S.; Landgraf, U.; Lohwasser, K.; Ludwig, I.; Ludwig, J.; Lumb, D.; Maassen, M.; Mahout, G.; Meinhardt, J.; Mohr, W.; Nilsen, H.; Parzefall, U.; Bueso, X. Portell; Rammensee, M.; Runge, K.; Rurikova, Z.; Schmidt, E.; Schumacher, M.; Siegert, F.; Stoerig, K.; Sundermann, J. E.; Temming, K. K.; Thoma, S.; Tobias, J.; Tsiskaridze, V.; Venturi, M.; Vivarelli, I.; von Radziewski, H.; Warsinsky, M.; Weiser, C.; Wiik, L. A. M.; Winkelmann, S.; Xie, S.; Zimmermann, S.] Univ Freiburg, Fak Math & Phys, D-79104 Freiburg, Germany |
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Amer Physical Soc |
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English |
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Series Issue |
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ISSN |
0031-9007 |
ISBN |
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Expedition |
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Conference |
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Notes |
ISI:000286750400009 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial  |
516 |
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Author |
ATLAS Collaboration (Aad, G. et al); Amoros, G.; Cabrera Urban, S.; Castillo Gimenez, V.; Costa, M.J.; Escobar, C.; Ferrer, A.; Fuster, J.; Garcia, C.; Gonzalez de la Hoz, S.; Hernandez Jimenez, Y.; Higon-Rodriguez, E.; Irles Quiles, A.; Kaci, M.; Lacasta, C.; Lacuesta, V.R.; Marti-Garcia, S.; Miñano, M.; Mitsou, V.A.; Moles-Valls, R.; Moreno Llacer, M.; Oliver Garcia, E.; Perez Garcia-Estañ, M.T.; Ros, E.; Salt, J.; Sanchis-Lozano, M.A.; Solans, C.A.; Sanchez, J.; Torro Pastor, E.; Valladolid Gallego, E.; Valls Ferrer, J.A.; Villaplana Perez, M.; Vos, M.; Wildauer, A. |
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Title |
Charged-particle multiplicities in pp interactions at root s=900 GeV measured with the ATLAS detector at the LHC |
Type |
Journal Article |
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Year |
2010 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
688 |
Issue |
1 |
Pages |
21-42 |
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Keywords |
Charged-particle; Multiplicities; 900 GeV; ATLAS; LHC; Minimum bias |
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Abstract |
The first measurements from proton-proton collisions recorded with the ATLAS detector at the LHC are presented. Data were collected in December 2009 using a minimum-bias trigger during collisions at a centre-of-mass energy of 900 GeV. The charged-particle multiplicity, its dependence on transverse momentum and pseudorapidity, and the relationship between mean transverse momentum and charged-particle multiplicity are measured for events with at least one charged particle in the kinematic range vertical bar eta vertical bar < 2.5 and p(T) > 500 MeV. The measurements are compared to Monte Carlo models of proton-proton collisions and to results from other experiments at the same centre-of-mass energy. The charged-particle multiplicity per event and unit of pseudorapidity eta = 0 is measured to be 1.333 +/- 0.003(stat.) +/- 0.040(syst.), which is 5-15% higher than the Monte Carlo models predict. |
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Address |
[Aad, G.; Ahles, F.; Aktas, A.; Anders, C. F.; Beckingham, M.; Bernhard, R.; Bianchi, R. M.; Bitenc, U.; Bruneliere, R.; Caron, S.; Carpentieri, C.; Christov, A.; Dahlhoff, A.; Dietrich, J.; Dingfelder, D. J.; Eckert, S.; Hartert, J.; Heldmann, M.; Herten, G.; Horner, S.; Jakobs, K.; Janus, M.; Joos, D.; Ketterer, C.; Koenig, S.; Kollefrath, M.; Kononov, A. I.; Kramer, A.; Kuehn, S.; Lai, S.; Landgraf, U.; Lohwasser, K.; Ludwig, I.; Ludwig, J.; Lumb, D.; Maassen, M.; Mahboubi, K.; Mazur, M.; Meinhardt, J.; Meirose, B.; Messmer, I.; Mohr, W.; Nilsen, H.; Parzefall, U.; Pfeifer, B.; Bueso, X. Portell; Rammensee, M.; Runge, K.; Rurikova, Z.; Schroff, D.; Schumacher, M.; Stoerig, K.; Sundermann, J. E.; Thoma, S.; Tobias, J.; Venturi, M.; Vivarelli, I.; von Radziewski, H.; Warsinsky, M.; Webel, M.; Weiser, C.; Werner, M.; Wiik, L. A. M.; Xie, S.; Zimmermann, S.] Univ Freiburg, Fak Math & Phys, D-79104 Freiburg, Germany, Email: atlas.secretariat@cern.ch |
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Publisher |
Elsevier Science Bv |
Place of Publication |
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Language |
English |
Summary Language |
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Original Title |
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Edition |
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ISSN |
0370-2693 |
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Conference |
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Notes |
ISI:000286150500001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
515 |
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Author |
CDF Collaboration (Aaltonen, T. et al); Cabrera, S. |
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Title |
Measurement of the WW plus WZ production cross section using a matrix element technique in lepton plus jets events |
Type |
Journal Article |
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Year |
2010 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
82 |
Issue |
11 |
Pages |
112001 - 15pp |
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Keywords |
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Abstract |
We present a measurement of the WW + WZ production cross section observed in a final state consisting of an identified electron or muon, two jets, and missing transverse energy. The measurement is carried out in a data sample corresponding to up to 4.6 fb(-1) of integrated luminosity at root s = 1.96 TeV collected by the CDF II detector. Matrix element calculations are used to separate the diboson signal from the large backgrounds. The WW + WZ cross section is measured to be 17.4 +/- 3.3 pb in agreement with standard model predictions. A fit to the dijet invariant mass spectrum yields a compatible cross section measurement. |
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Address |
[Aaltonen, T.; Brucken, E.; Devoto, F.; Mehtala, P.; Orava, R.] Univ Helsinki, Dept Phys, Div High Energy Phys, FIN-00014 Helsinki, Finland |
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Publisher |
Amer Physical Soc |
Place of Publication |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1550-7998 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
ISI:000286565600004 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
514 |
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Author |
CDF Collaboration (Aaltonen, T. et al); Cabrera, S. |
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Title |
Improved Search for a Higgs Boson Produced in Association with Z -> l(+)l(-) in p(p)over-bar Collisions at root s=1.96 TeV |
Type |
Journal Article |
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Year |
2010 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
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Volume |
105 |
Issue |
25 |
Pages |
251802 - 7pp |
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Keywords |
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Abstract |
We search for the standard model Higgs boson produced with a Z boson in 4: 1 fb(-1) of integrated luminosity collected with the CDF II detector at the Tevatron. In events consistent with the decay of the Higgs boson to a bottom-quark pair and the Z boson to electrons or muons, we set 95% credibility level upper limits on the ZH production cross section multiplied by the H -> b (b) over bar branching ratio. Improved analysis methods enhance signal sensitivity by 20% relative to previous searches. At a Higgs boson mass of 115 GeV/c(2) we set a limit of 5.9 times the standard model cross section. |
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Address |
[Aaltonen, T.; Brucken, E.; Devoto, F.; Mehtala, P.; Orava, R.] Univ Helsinki, Dept Phys, Div High Energy Phys, FIN-00014 Helsinki, Finland |
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Corporate Author |
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Thesis |
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Publisher |
Amer Physical Soc |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0031-9007 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
ISI:000286750400004 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
513 |
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| Permanent link to this record |
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Author |
Aristizabal Sierra, D.; Bazzocchi, F.; de Medeiros Varzielas, I.; Merlo, L.; Morisi, S. |
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Title |
Tri/Bi-maximal lepton mixing and leptogenesis |
Type |
Journal Article |
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Year |
2010 |
Publication |
Nuclear Physics B |
Abbreviated Journal |
Nucl. Phys. B |
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Volume |
827 |
Issue |
1-2 |
Pages |
34-58 |
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Keywords |
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Abstract |
In models with flavour symmetries added to the gauge group of the Standard Model the CP-violating asymmetry necessary for leptogenesis may be related with low-energy parameters. A particular case of interest is when the flavour symmetry produces exact Tri/Bi-maximal lepton mixing leading to a vanishing CP-violating asymmetry. In this paper we present a model-independent discussion that confirms this always occurs for unflavoured leptogenesis in type I see-saw scenarios, noting however that Tri/Bi-maximal mixing does not imply a vanishing asymmetry in general scenarios where there is interplay between type I and other see-saws. We also consider a specific model where the exact Tri/Bi-maximal mixing is lifted by corrections that can be parametrised by a small number of degrees of freedom and analyse in detail the existing link between low and high-energy parameters – focusing on how the deviations from Tri/Bi-maximal are connected to the parameters governing leptogenesis. |
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Address |
[Merlo, L.] Univ Padua, Dipartimento Fis G Galilei, Ist Nazl Fis Nucl, Sez Padova, I-35131 Padua, Italy, Email: daristi@lnf.infn.it |
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Corporate Author |
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Thesis |
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Publisher |
Elsevier Science Bv |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0550-3213 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
ISI:000272669900002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
512 |
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| Permanent link to this record |
