FAKTORI KOJI POMAŽU IZDVAJANJU BENTOSKIH CIJANOBAKTERIJA IZ FAZA MIROVANJA: PREGLED

The sediment-water interface in aquatic systems is an environment connecting bottom sediments with the overlying water column. This transition zone can be easily disturbed by mechanical mixing (bioturbation) caused by foraging fish and/or macroinvertebrates moving around and stirring sediment layers. The sediment of still water ecosystems is largely known as a reservoir of resting stages of various planktonic plants, including cyanobacteria (blue-green algae) and invertebrates. The ecological and evolutionary dynamics of cyanobacteria is in part a function of the numbers and ages of diapausing stages hatching from aquatic sediments. Successful recruitment from this ”seed bank” must depend upon the resting stages being present at or near the sediment surface. Often, however, they are found as deep as 15 to 30 cm in the mud. Bioturbation may thus provide a mechanism for the regular return of buried cyanobacteria resting stages to the sediment surface.Prostor površine bentala (sediment-voda) je okoliš koji povezuje sediment dna i stupac vode iznad. Ova prijelazna zona lako se može uznemiriti mehaničkim miješanjem (bioturbacijom) uzrokovanim ribom koja je u potrazi za hranom i kretanjem makrozoobentosa kroz slojeve sedimenta. Sediment ekosustava stajaćica uglavnom je poznat kao “rezervoar” za mirovanje različitih planktonskih biljaka, uključujući cijanobakterije (modrozelene alge) i beskralježnjake. Ekološka i evolucijska dinamika cijanobakterija ima utjecajnu ulogu za brojne generacijske stadije mirovanja nastale u akvatičnom ekosustavu. Uspješno izdvajanje iz tih “banki stanica” mora ovisiti o fazama mirovanja u/ili blizu površine sedimenta. Međutim, cijanobakterije se često nalaze 15 do 30 cm dubine u mulju. Mehaničko miješanje (bioturbacija) može osigurati povratak ukopanih cijanobakterija iz faza mirovanja na površinu sedimenta

FAKTORI KOJI POMAŽU IZDVAJANJU BENTOSKIH CIJANOBAKTERIJA IZ FAZA MIROVANJA: PREGLED

The sediment-water interface in aquatic systems is an environment connecting bottom sediments with the overlying water column. This transition zone can be easily disturbed by mechanical mixing (bioturbation) caused by foraging fish and/or macroinvertebrates moving around and stirring sediment layers. The sediment of still water ecosystems is largely known as a reservoir of resting stages of various planktonic plants, including cyanobacteria (blue-green algae) and invertebrates. The ecological and evolutionary dynamics of cyanobacteria is in part a function of the numbers and ages of diapausing stages hatching from aquatic sediments. Successful recruitment from this ”seed bank” must depend upon the resting stages being present at or near the sediment surface. Often, however, they are found as deep as 15 to 30 cm in the mud. Bioturbation may thus provide a mechanism for the regular return of buried cyanobacteria resting stages to the sediment surface.Prostor površine bentala (sediment-voda) je okoliš koji povezuje sediment dna i stupac vode iznad. Ova prijelazna zona lako se može uznemiriti mehaničkim miješanjem (bioturbacijom) uzrokovanim ribom koja je u potrazi za hranom i kretanjem makrozoobentosa kroz slojeve sedimenta. Sediment ekosustava stajaćica uglavnom je poznat kao “rezervoar” za mirovanje različitih planktonskih biljaka, uključujući cijanobakterije (modrozelene alge) i beskralježnjake. Ekološka i evolucijska dinamika cijanobakterija ima utjecajnu ulogu za brojne generacijske stadije mirovanja nastale u akvatičnom ekosustavu. Uspješno izdvajanje iz tih “banki stanica” mora ovisiti o fazama mirovanja u/ili blizu površine sedimenta. Međutim, cijanobakterije se često nalaze 15 do 30 cm dubine u mulju. Mehaničko miješanje (bioturbacija) može osigurati povratak ukopanih cijanobakterija iz faza mirovanja na površinu sedimenta

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Measurements of the charge asymmetry in top-quark pair production in the dilepton final state at s √ =8 TeV with the ATLAS detector

Measurements of the top-antitop quark pair production charge asymmetry in the dilepton channel, characterized by two high-pT leptons (electrons or muons), are presented using data corresponding to an integrated luminosity of 20.3  fb−1 from pp collisions at a center-of-mass energy s√=8  TeV collected with the ATLAS detector at the Large Hadron Collider at CERN. Inclusive and differential measurements as a function of the invariant mass, transverse momentum, and longitudinal boost of the tt¯ system are performed both in the full phase space and in a fiducial phase space closely matching the detector acceptance. Two observables are studied: AℓℓC based on the selected leptons and Att¯C based on the reconstructed tt¯ final state. The inclusive asymmetries are measured in the full phase space to be AℓℓC=0.008±0.006 and Att¯C=0.021±0.016, which are in agreement with the Standard Model predictions of AℓℓC=0.0064±0.0003 and Att¯C=0.0111±0.0004

Measurement of the top quark forward-backward production asymmetry and the anomalous chromoelectric and chromomagnetic moments in pp collisions at √s = 13 TeV

Abstract The parton-level top quark (t) forward-backward asymmetry and the anomalous chromoelectric (d̂ t) and chromomagnetic (μ̂ t) moments have been measured using LHC pp collisions at a center-of-mass energy of 13 TeV, collected in the CMS detector in a data sample corresponding to an integrated luminosity of 35.9 fb−1. The linearized variable AFB(1) is used to approximate the asymmetry. Candidate t t ¯ events decaying to a muon or electron and jets in final states with low and high Lorentz boosts are selected and reconstructed using a fit of the kinematic distributions of the decay products to those expected for t t ¯ final states. The values found for the parameters are AFB(1)=0.048−0.087+0.095(stat)−0.029+0.020(syst),μ̂t=−0.024−0.009+0.013(stat)−0.011+0.016(syst), and a limit is placed on the magnitude of | d̂ t| < 0.03 at 95% confidence level. [Figure not available: see fulltext.

Measurement of t(t)over-bar normalised multi-differential cross sections in pp collisions at root s=13 TeV, and simultaneous determination of the strong coupling strength, top quark pole mass, and parton distribution functions

Peer reviewe

An embedding technique to determine ττ backgrounds in proton-proton collision data

An embedding technique is presented to estimate standard model tau tau backgrounds from data with minimal simulation input. In the data, the muons are removed from reconstructed mu mu events and replaced with simulated tau leptons with the same kinematic properties. In this way, a set of hybrid events is obtained that does not rely on simulation except for the decay of the tau leptons. The challenges in describing the underlying event or the production of associated jets in the simulation are avoided. The technique described in this paper was developed for CMS. Its validation and the inherent uncertainties are also discussed. The demonstration of the performance of the technique is based on a sample of proton-proton collisions collected by CMS in 2017 at root s = 13 TeV corresponding to an integrated luminosity of 41.5 fb(-1).Peer reviewe

Measurement of the Splitting Function in &ITpp &ITand Pb-Pb Collisions at root&ITsNN&IT=5.02 TeV

Data from heavy ion collisions suggest that the evolution of a parton shower is modified by interactions with the color charges in the dense partonic medium created in these collisions, but it is not known where in the shower evolution the modifications occur. The momentum ratio of the two leading partons, resolved as subjets, provides information about the parton shower evolution. This substructure observable, known as the splitting function, reflects the process of a parton splitting into two other partons and has been measured for jets with transverse momentum between 140 and 500 GeV, in pp and PbPb collisions at a center-of-mass energy of 5.02 TeV per nucleon pair. In central PbPb collisions, the splitting function indicates a more unbalanced momentum ratio, compared to peripheral PbPb and pp collisions.. The measurements are compared to various predictions from event generators and analytical calculations.Peer reviewe

Measurement of nuclear modification factors of gamma(1S)), gamma(2S), and gamma(3S) mesons in PbPb collisions at root s(NN)=5.02 TeV

The cross sections for ϒ(1S), ϒ(2S), and ϒ(3S) production in lead-lead (PbPb) and proton-proton (pp) collisions at √sNN = 5.02 TeV have been measured using the CMS detector at the LHC. The nuclear modification factors, RAA, derived from the PbPb-to-pp ratio of yields for each state, are studied as functions of meson rapidity and transverse momentum, as well as PbPb collision centrality. The yields of all three states are found to be significantly suppressed, and compatible with a sequential ordering of the suppression, RAA(ϒ(1S)) > RAA(ϒ(2S)) > RAA(ϒ(3S)). The suppression of ϒ(1S) is larger than that seen at √sNN = 2.76 TeV, although the two are compatible within uncertainties. The upper limit on the RAA of ϒ(3S) integrated over pT, rapidity and centrality is 0.096 at 95% confidence level, which is the strongest suppression observed for a quarkonium state in heavy ion collisions to date. © 2019 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP3.Peer reviewe

Electroweak production of two jets in association with a Z boson in proton-proton collisions root s =13 TeV

A measurement of the electroweak (EW) production of two jets in association with a Z boson in proton-proton collisions at root s = 13 TeV is presented, based on data recorded in 2016 by the CMS experiment at the LHC corresponding to an integrated luminosity of 35.9 fb(-1). The measurement is performed in the lljj final state with l including electrons and muons, and the jets j corresponding to the quarks produced in the hard interaction. The measured cross section in a kinematic region defined by invariant masses m(ll) > 50 GeV, m(jj) > 120 GeV, and transverse momenta P-Tj > 25 GeV is sigma(EW) (lljj) = 534 +/- 20 (stat) fb (syst) fb, in agreement with leading-order standard model predictions. The final state is also used to perform a search for anomalous trilinear gauge couplings. No evidence is found and limits on anomalous trilinear gauge couplings associated with dimension-six operators are given in the framework of an effective field theory. The corresponding 95% confidence level intervals are -2.6 <cwww/Lambda(2) <2.6 TeV-2 and -8.4 <cw/Lambda(2) <10.1 TeV-2. The additional jet activity of events in a signal-enriched region is also studied, and the measurements are in agreement with predictions.Peer reviewe