The results of a search for pair production of the scalar partners of bottom quarks in 2.05 fb(-1) of pp collisions at sqrts=7 TeV using the ATLAS experiment are reported. Scalar bottom quarks are ...searched for in events with large missing transverse momentum and two jets in the final state, where both jets are identified as originating from a bottom quark. In an R-parity conserving minimal supersymmetric scenario, assuming that the scalar bottom quark decays exclusively into a bottom quark and a neutralino, 95% confidence-level upper limits are obtained in the b(1) - χ(1)(0) mass plane such that for neutralino masses below 60 GeV scalar bottom masses up to 390 GeV are excluded.
A measurement of the jet activity in
events produced in proton–proton collisions at a centre-of-mass energy of 7 TeV is presented, using 2.05 fb
−1
of integrated luminosity collected by the ATLAS ...detector at the Large Hadron Collider. The
events are selected in the dilepton decay channel with two identified
b
-jets from the top quark decays. Events are vetoed if they contain an additional jet with transverse momentum above a threshold in a central rapidity interval. The fraction of events surviving the jet veto is presented as a function of this threshold for four different central rapidity interval definitions. An alternate measurement is also performed, in which events are vetoed if the scalar transverse momentum sum of the additional jets in each rapidity interval is above a threshold. In both measurements, the data are corrected for detector effects and compared to the theoretical models implemented in
MC@NLO
,
Powheg
,
Alpgen
and
Sherpa
. The experimental uncertainties are often smaller than the spread of theoretical predictions, allowing deviations between data and theory to be observed in some regions of phase space.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The top quark mass has been measured using the template method in the
channel based on data recorded in 2011 with the ATLAS detector at the LHC. The data were taken at a proton-proton centre-of-mass ...energy of
and correspond to an integrated luminosity of 1.04 fb
−1
. The analyses in the
e
+jets and
μ
+jets decay channels yield consistent results. The top quark mass is measured to be
m
top
=174.5±0.6
stat
±2.3
syst
GeV.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A measurement of the top-antitop production charge asymmetry
A
C
is presented using data corresponding to an integrated luminosity of 1.04 fb
−1
of
pp
collisions at
TeV collected by the ATLAS ...detector at the LHC. Events are selected with a single lepton (electron or muon), missing transverse momentum and at least four jets of which at least one jet is identified as coming from a
b
-quark. A kinematic fit is used to reconstruct the
event topology. After background subtraction, a Bayesian unfolding procedure is performed to correct for acceptance and detector effects. The measured value of
A
C
is
, consistent with the prediction from the
MC@NLO
Monte Carlo generator of
A
C
=0.006±0.002. Measurements of
A
C
in two ranges of invariant mass of the top-antitop pair are also shown.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A search for top quark pair resonances in final states containing at least one electron or muon has been performed with the ATLAS experiment at the CERN Large Hadron Collider. The search uses a data ...sample corresponding to an integrated luminosity of 2.05 fb
−1
, which was recorded in 2011 at a proton-proton centre-of-mass energy of 7 TeV. No evidence for a resonance is found and limits are set on the production cross-section times branching ratio to
for narrow and wide resonances. For narrow
Z
′ bosons, the observed 95 % Bayesian credibility level limits range from 9.3 pb to 0.95 pb for masses in the range of
m
Z
′
=500 GeV to
m
Z
′
=1300 GeV. The corresponding excluded mass region for a leptophobic topcolour
Z
′ boson (Kaluza-Klein gluon excitation in the Randall-Sundrum model) is
m
Z
′
<880 GeV (
).
Azimuthal decorrelations between the two central jets with the largest transverse momenta are sensitive to the dynamics of events with multiple jets. We present a measurement of the normalized ...differential cross section based on the full data set (∫Ldt=36 pb(-1)) acquired by the ATLAS detector during the 2010 sqrt(s)=7 TeV proton-proton run of the LHC. The measured distributions include jets with transverse momenta up to 1.3 TeV, probing perturbative QCD in a high-energy regime.
A measurement of the production cross-section for top quark pairs (
) in
pp
collisions at
is presented using data recorded with the ATLAS detector at the Large Hadron Collider. Events are selected in ...two different topologies: single lepton (electron
e
or muon
μ
) with large missing transverse energy and at least four jets, and dilepton (
ee
,
μμ
or
eμ
) with large missing transverse energy and at least two jets. In a data sample of 2.9 pb
−1
, 37 candidate events are observed in the single-lepton topology and 9 events in the dilepton topology. The corresponding expected backgrounds from non-
Standard Model processes are estimated using data-driven methods and determined to be 12.2±3.9 events and 2.5±0.6 events, respectively. The kinematic properties of the selected events are consistent with SM
production. The inclusive top quark pair production cross-section is measured to be
The measurement agrees with perturbative QCD calculations.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The paper presents a description of the epidemiological situation on Hantavirus infection incidence in the countries around the world. Comparative analysis of the intensity and dynamics of the ...epidemiological process of hemorrhagic fever with renal syndrome (HFRS) in the Russian Federation by Federal Districts in 2021 has been carried out and forecast of the HFRS incidence for 2022 prepared. The study has revealed that tense situation on incidence of hantavirus diseases was observed in the world in 2021. On the territory of the Russian Federation, there was a decrease in the HFRS incidence in 2021 (by 1.7 times compared to 2020). However, the results of epidemiological analysis of the HFRS incidence, epizootiological data and laboratory studies in certain Federal Districts of the Russian Federation indicate that the epidemiological situation on HFRS remains tense. High risk of HFRS infection is predicted in a number of regions of the country due to the favorable natural and climatic conditions in the winter period of 2021–2022 with a heavy snow cover, which contributed to the under-snow reproduction of small mammals, the main carriers of HFRS. The presence of infected rodents testifies to a high likelihood of complication of the epidemiological situation in areas of increased epidemic risk of HFRS.
Aim
. To assess the changes in cardiology diagnostics scope in the Russian Federation during the coronavirus disease 2019 (COVID-19) pandemic.
Material and methods
. In an online survey organized by ...the Division of Human Health of the International Atomic Energy Agency (IAEA), including questions about changes in the workflow of diagnostic laboratories and the scope of cardiac diagnostics from March 2019 (pre-pandemic) to April 2020 (first wave of the pandemic) and April 2021 (recovery stage), 15 Russian medical centers from 5 cities took part.
Results
. The decrease in the diagnostics scope by April 2020 by 59,3% compared to March 2019, by April 2021, stopped and was replaced by growth (+7,1%, the recovery rate, 112,1%). The greatest increase was in routine examinations, such as echocardiography (+11,6%), stress echocardiography (+18,7%), stress single photon emission computed tomography (+9,7%), and to a lesser extent resting computed tomography angiography (+7,0%) and magnetic resonance imaging (+6,6%). The performance of stress electrocardiography, stress magnetic resonance imaging and positron emission tomography for the diagnosis of endocarditis in April 2021 compared to March 2019 decreased by 10,3%, 63,2% and 62,5%, respectively.
Conclusion
. Due to the resumption of patient admissions for cardiac examinations during the ongoing COVID-19 pandemic, with the anti-epidemic measures taken and certain changes in the workflow, there has been a recovery in the diagnostics scope in most of the included centers.
The paper considers dependences of electric power supply cost on transferred power and reveals conditions of economical efficiency of electric power transmission in power system.
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