Sofia University

About: Sofia University is a education organization based out in Sofia, Bulgaria. It is known for research contribution in the topics: Large Hadron Collider & Laser. The organization has 8533 authors who have published 15730 publications receiving 306320 citations. The organization is also known as: University of Sofia & BFUS.

Performance of the CMS Level-1 trigger in proton-proton collisions at √s = 13 TeV

Abstract: At the start of Run 2 in 2015, the LHC delivered proton-proton collisions at a center-of-mass energy of 13\TeV. During Run 2 (years 2015–2018) the LHC eventually reached a luminosity of 2.1× 1034 cm-2s-1, almost three times that reached during Run 1 (2009–2013) and a factor of two larger than the LHC design value, leading to events with up to a mean of about 50 simultaneous inelastic proton-proton collisions per bunch crossing (pileup). The CMS Level-1 trigger was upgraded prior to 2016 to improve the selection of physics events in the challenging conditions posed by the second run of the LHC. This paper describes the performance of the CMS Level-1 trigger upgrade during the data taking period of 2016–2018. The upgraded trigger implements pattern recognition and boosted decision tree regression techniques for muon reconstruction, includes pileup subtraction for jets and energy sums, and incorporates pileup-dependent isolation requirements for electrons and tau leptons. In addition, the new trigger calculates high-level quantities such as the invariant mass of pairs of reconstructed particles. The upgrade reduces the trigger rate from background processes and improves the trigger efficiency for a wide variety of physics signals.

Chapter 4 Changes in the oceanography of the Mediterranean Sea and their link to climate variability

Abstract: Publisher Summary This chapter presents a description of the major features of the large-scale Mediterranean Sea circulation and the most important changes that have been observed in the physical oceanography of the basin. It describes the basic circulation of the Mediterranean Sea that has long been recognized to be that of a concentration basin. The transformation of the inflowing Atlantic water to outflowing Mediterranean water is made through a thermohaline cell that involves the whole basin and leads to the formation of the Levantine Intermediate Water (LIW). The chapter discusses the oceanographic changes within the Mediterranean Basin concentrating mainly on the internal processes of the basin in relation to the regional forcing. It focuses on the large-scale thermohaline circulation of the Mediterranean and examines sub-basin processes when these are directly linked with deep water formation. It discusses two other key factors that are linked to the oceanic circulation, sea level variations and the wind–wave field.

A Roadmap for HEP Software and Computing R&D for the 2020s

Abstract: Particle physics has an ambitious and broad experimental programme for the coming decades. This programme requires large investments in detector hardware, either to build new facilities and experiments, or to upgrade existing ones. Similarly, it requires commensurate investment in the R&D of software to acquire, manage, process, and analyse the shear amounts of data to be recorded. In planning for the HL-LHC in particular, it is critical that all of the collaborating stakeholders agree on the software goals and priorities, and that the efforts complement each other. In this spirit, this white paper describes the R&D activities required to prepare for this software upgrade.