scholarly journals Search for heavy particles in the b -tagged dijet mass distribution with additional b -tagged jets in proton-proton collisions at s=13  TeV with the ATLAS experiment

2022 ◽  
Vol 105 (1) ◽  
Author(s):  
G. Aad ◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
K. Abeling ◽  
...  
2020 ◽  
Vol 225 ◽  
pp. 01002
Author(s):  
Andreé Sopczak

Medipix and Timepix devices, installed in the ATLAS cavern at the LHC, have provided valuable complementary luminosity information. Results are presented from measurements with Timepix3 (TPX3) detectors. In contrast with previously employed frame-based data acquisition, the TPX3 detector remains active continuously, sending information on pixel hits as they occur. Hit- and cluster-counting methods were used for the luminosity determination of the LHC protonproton collisions. The LHC luminosity versus time is determined using these two methods and fitted to a simple model, which incorporates luminosity reduction from single bunch and beam-beam interactions. The precision of the luminosity determination could be improved by counting the number of clusters, instead of just pixel hits. The internal precision and long-term stability of the TPX3 luminosity measurement are below 0.5%. TPX3, owing to its 1.56 ns time-tagging, is able to resolve the time structure of the luminosity due to the collisions of individual proton bunches when integrated over an LHC fill.


2018 ◽  
Vol 192 ◽  
pp. 00007
Author(s):  
Gabriele Chiodini

Jet substructure observables are powerful tools for the identification of boosted heavy particles and for probing QCD at different energy scales in proton-proton collisions at the LHC. In this work three recent ATLAS measurements sensitive to soft QCD effects and performed with the use of jet substructures are described. Their are kt splitting scales, soft-drop jet masses and pull-jet angles. Some discrepancies between data and predictions are observed in the non-perturbative regime.


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