Search results for "TLA"
showing 4 items of 1764 documents
Brūnkakļa Aythya ferina izplatības un skaita izmaiņas Latvijā 1958-2019
2020
Eiropas apdraudēto putnu sarakstā (European Red List of Birds 2015) redzams, ka pēdējos 20 gados brūnkakļu Aythya ferina Eiropas un pasaules populācijām ir vērojams būtisks izplatības un skaita samazinājums, kā rezultātā brūnkaklis ir iekļaujams apdraudēto (Vulnerable) sugu sarakstā. Savukārt, 2019. gada nogalē pieņemts lēmums šo sugu svītrot no Latvijas medījamo sugu saraksta. Šajā darbā izveidots pārskats par brūnkakļa izplatības un skaita izmaiņām Latvijā, izmantojot datus no divām ilgtermiņa ligzdojošo ūdensputnu uzskaitēm Engures (1958-2019) un Kaņiera (2005-2019) ezeros, kā arī datus no trim ligzdojošo putnu atlantiem: 1980-1984; 2000-2004; 2013-2017. Darbā izvērtēti arī populāciju ie…
Search for scalar leptoquarks in pp collisions at $\sqrt{s}$=13 TeV with the ATLAS experiment
2016
An inclusive search for a new-physics signature of lepton-jet resonances has been performed by the ATLAS experiment. Scalar leptoquarks, pair-produced in pp collisions at s √s = 13 TeV at the large hadron collider, have been considered. An integrated luminosity of 3.2 fb-1, corresponding to the full 2015 dataset was used. First (second) generation leptoquarks were sought in events with two electrons (muons) and two or more jets. The observed event yield in each channel is consistent with Standard Model background expectations. The observed (expected) lower limits on the leptoquark mass at 95% confidence level are 1100 and 1050 GeV (1160 and 1040 GeV) for first and second generation leptoqua…
Search for the Decay of the Higgs Boson to Charm Quarks with the ATLAS Experiment
2018
A direct search for the standard model Higgs boson decaying to a pair of charm quarks is presented. Associated production of the Higgs and Z bosons, in the decay mode ZH→ℓ+ℓ−c¯c is studied. A data set with an integrated luminosity of 36.1 fb−1 of pp collisions at √s=13TeV recorded by the ATLAS experiment at the LHC is used. The H→c¯c signature is identified using charm-tagging algorithms. The observed (expected) upper limit on σ(pp→ZH)×B(H→c¯c) is 2.7 (3.9+2.1−1.1) pb at the 95% confidence level for a Higgs boson mass of 125 GeV, while the standard model value is 26 fb.
Beam-induced and cosmic-ray backgrounds observed in the ATLAS detector during the LHC 2012 proton-proton running period
2016
This paper discusses various observations on beam-induced and cosmic-ray backgrounds in the ATLAS detector during the LHC 2012 proton-proton run. Building on published results based on 2011 data, the correlations between background and residual pressure of the beam vacuum are revisited. Ghost charge evolution over 2012 and its role for backgrounds are evaluated. New methods to monitor ghost charge with beam-gas rates are presented and observations of LHC abort gap population by ghost charge are discussed in detail. Fake jets from colliding bunches and from ghost charge are analysed with improved methods, showing that ghost charge in individual radio-frequency buckets of the LHC can be resol…