scholarly journals Measurement of the four-lepton invariant mass spectrum in 13 TeV proton-proton collisions with the ATLAS detector

2019 ◽  
Vol 2019 (4) ◽  
Author(s):  
M. Aaboud ◽  
◽  
G. Aad ◽  
B. Abbott ◽  
O. Abdinov ◽  
...  
Keyword(s):  
Mass Spectrum ◽  
Invariant Mass ◽  
Invariant Mass Spectrum ◽  
Atlas Detector ◽  
Proton Proton ◽  
Proton Collisions ◽  
Proton Proton Collisions

scholarly journals Measurements of differential cross-sections in four-lepton events in 13 TeV proton-proton collisions with the ATLAS detector

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
◽  
G. Aad ◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Standard Model ◽  
Invariant Mass ◽  
Cross Sections ◽  
Differential Cross ◽  
Atlas Detector ◽  
Boson Production ◽  
Differential Cross Sections ◽  
Proton Proton ◽  
Proton Collisions ◽  
Proton Proton Collisions

Abstract Measurements of four-lepton differential and integrated fiducial cross-sections in events with two same-flavour, opposite-charge electron or muon pairs are presented. The data correspond to 139 fb−1 of $$ \sqrt{s} $$ s = 13 TeV proton-proton collisions, collected by the ATLAS detector during Run 2 of the Large Hadron Collider (2015–2018). The final state has contributions from a number of interesting Standard Model processes that dominate in different four-lepton invariant mass regions, including single Z boson production, Higgs boson production and on-shell ZZ production, with a complex mix of interference terms, and possible contributions from physics beyond the Standard Model. The differential cross-sections include the four-lepton invariant mass inclusively, in slices of other kinematic variables, and in different lepton flavour categories. Also measured are dilepton invariant masses, transverse momenta, and angular correlation variables, in four regions of four-lepton invariant mass, each dominated by different processes. The measurements are corrected for detector effects and are compared with state-of-the-art Standard Model calculations, which are found to be consistent with the data. The Z → 4ℓ branching fraction is extracted, giving a value of (4.41 ± 0.30) × 10−6. Constraints on effective field theory parameters and a model based on a spontaneously broken B − L gauge symmetry are also evaluated. Further reinterpretations can be performed with the provided information.

scholarly journals Search for new phenomena in photon+jet events collected in proton–proton collisions at s=8 TeV with the ATLAS detector

2014 ◽  
Vol 728 ◽  
pp. 562-578 ◽  
Author(s):  
G. Aad ◽  
T. Abajyan ◽  
B. Abbott ◽  
J. Abdallah ◽  
S. Abdel Khalek ◽  
...  
Keyword(s):  
Atlas Detector ◽  
Proton Proton ◽  
Proton Collisions ◽  
New Phenomena ◽  
Proton Proton Collisions

ππ PRODUCTION IN PROTON-PROTON COLLISIONS

2007 ◽  
Vol 22 (02n03) ◽  
pp. 509-513 ◽  
Author(s):  
◽  
T. Skorodko ◽  
M. Bashkanov ◽  
D. Bogoslowsky ◽  
H. Calén ◽  
...  
Keyword(s):  
Pion Production ◽  
Invariant Mass Spectrum ◽  
Light Nuclei ◽  
Special Configuration ◽  
Proton Proton ◽  
Proton Collisions ◽  
Low Mass ◽  
Threshold Energies ◽  
Proton Proton Collisions ◽  
Mass Enhancement

At CELSIUS-WASA the two-pion production in proton-proton collisisons has been measured exclusively from threshold up to the energy regime, where both of the collision partners are expected to be excited to the Δ state. The measurements constitute the first kinematically complete data samples of solid statistics in this energy range. Most of the data have been obtained for the π+π- and π0π0channels. Whereas at near-threshold energies the differential distributions can be succesfully explained by chiral dynamics and Roper excitation, respectively, the data for the π+π- channel in the ΔΔ region can be described only, if the special configuration (ΔΔ)0+ is assumed. The data for the π0π0 channel moreover exhibit a low-mass enhancement in the π0π0 invariant mass spectrum, which is reminiscent of the ABC-effect found in double-pionic fusion to light nuclei.

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