Two-particle Azimuthal correlations are measured with the ALICE apparatus in pp collisions at
s
=
13
TeV to explore strangeness- and multiplicity-related effects in the fragmentation of jets and the ...transition regime between bulk and hard production, probed with the condition that a strange meson (
K
S
0
) or baryon (
Λ
) with transverse momentum
p
T
>
3
GeV/
c
is produced. Azimuthal correlations between kaons or
Λ
hyperons with other hadrons are presented at midrapidity for a broad range of the trigger (
3
<
p
T
trigg
<
20
GeV/
c
) and associated particle
p
T
(1 GeV/
c
<
p
T
assoc
<
p
T
trigg
), for minimum-bias events and as a function of the event multiplicity. The near- and away-side peak yields are compared for the case of either
K
S
0
or
Λ
(
Λ
¯
) being the trigger particle with that of inclusive hadrons (a sample dominated by pions). In addition, the measurements are compared with predictions from PYTHIA 8 and EPOS LHC event generators.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The article considers the actual problem of transferring some tasks of the distance learning onto a mobile platform. The research was carried out on the basis of several generations of ...custom-designed software for the preparation of masters on the direction «Informatics and Computer Technlolgy» within the framework of the program «Architecture of Computer Technology and Information Systems». The paper describes the technology for developing and implementing a mobile application for a distance learning system for smartphones running the Android operating system. The task was to apply the system for the organization of distance learning in the international double-degree program in the framework of cooperation with foreign universities. The specificity of such an application lies in the possibility of teaching in English using software to combine the two training programs of participating universities to form individual training plans depending on the previous master's knowledge. It is planned to include special developments, for example, the use of task solvers to reduce the burden on teachers accompanying the learning process. This will reduce the time when solving difficult tasks as related to hardware implementation of algorithms for digital processing of information. Thus, we can speak about the expansion of the research part of this scientific project and the emerging possibility of using a mobile application for research and implementation of practices for obtaining professional skills and professional experience that occupy a significant place in the curriculum of undergraduates. The approach and methodology are proposed for implementing an individual distance learning system based on standard application modules using emulators. The results of experiments according to key parameters of the program system are presented.
Luminosity determination within the ALICE experiment is based on the measurement, in van der Meer scans, of the cross sections for visible processes involving one or more detectors (visible cross ...sections). In 2015 and 2018, the Large Hadron Collider provided Pb–Pb collisions at a centre-of-mass energy per nucleon pair of √sNN = 5.02 TeV. Two visible cross sections, associated with particle detection in the Zero Degree Calorimeter (ZDC) and in the V0 detector, were measured in a van der Meer scan.This article describes the experimental set-up and the analysis procedure, and presents the measurement results. The analysis involves a comprehensive study of beam-related effects and an improved fitting procedure, compared to previous ALICE studies, for the extraction of the visible cross section. The resulting uncertainty of both the ZDC-based and the V0-based luminosity measurement for the full sample is 2.5%. The inelastic cross section for hadronic interactions in Pb–Pb collisions at √sNN = 5.02 TeV, obtained by efficiency correction of the V0-based visible cross section, was measured to be 7.67 ± 0.25 b, in agreement with predictions using the Glauber model.
The production of
π
±
,
K
±
,
K
S
0
,
K
∗
(
892
)
0
,
p
,
ϕ
(
1020
)
,
Λ
,
Ξ
-
,
Ω
-
, and their antiparticles was measured in inelastic proton–proton (pp) collisions at a center-of-mass energy of
s
...= 13 TeV at midrapidity (
|
y
|
<
0.5
) as a function of transverse momentum (
p
T
) using the ALICE detector at the CERN LHC. Furthermore, the single-particle
p
T
distributions of
K
S
0
,
Λ
, and
Λ
¯
in inelastic pp collisions at
s
=
7
TeV are reported here for the first time. The
p
T
distributions are studied at midrapidity within the transverse momentum range
0
≤
p
T
≤
20
GeV/
c
, depending on the particle species. The
p
T
spectra, integrated yields, and particle yield ratios are discussed as a function of collision energy and compared with measurements at lower
s
and with results from various general-purpose QCD-inspired Monte Carlo models. A hardening of the spectra at high
p
T
with increasing collision energy is observed, which is similar for all particle species under study. The transverse mass and
x
T
≡
2
p
T
/
s
scaling properties of hadron production are also studied. As the collision energy increases from
s
= 7–13 TeV, the yields of non- and single-strange hadrons normalized to the pion yields remain approximately constant as a function of
s
, while ratios for multi-strange hadrons indicate enhancements. The
p
T
-differential cross sections of
π
±
,
K
±
and
p
(
p
¯
) are compared with next-to-leading order perturbative QCD calculations, which are found to overestimate the cross sections for
π
±
and
p
(
p
¯
) at high
p
T
.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
The knowledge of the material budget with a high precision is fundamental for measurements of direct photon
production using the photon conversion method due to its direct impact on the ...total systematic uncertainty. Moreover, it influences many aspects of the charged-particle reconstruction performance. In this article, two procedures to determine data-driven corrections to the material-budget description in ALICE simulation software are developed.
One is based on the precise knowledge of the gas composition in the Time Projection Chamber. The other is based on the robustness of the ratio between the produced number of photons and charged particles, to a large extent due to the approximate isospin symmetry in the number of produced neutral and charged pions. Both methods are applied to ALICE data allowing for a reduction of the
overall material budget systematic uncertainty from 4.5% down to
2.5%. Using these methods, a locally correct material budget is also
achieved. The two proposed methods are generic and can be applied to
any experiment in a similar fashion.
The production of the $\Lambda $(1520) baryonic resonance has been measured at midrapidity in inelastic pp collisions at $\sqrt{s} = 7\ \hbox {TeV}$ and in p–Pb collisions at $\sqrt{s_{\mathrm{NN}}} ...= 5.02\ \hbox {TeV}$ for non-single diffractive events and in multiplicity classes. The resonance is reconstructed through its hadronic decay channel $\Lambda $(1520) $\rightarrow \hbox {pK}^{-}$ and the charge conjugate with the ALICE detector. The integrated yields and mean transverse momenta are calculated from the measured transverse momentum distributions in pp and p–Pb collisions. The mean transverse momenta follow mass ordering as previously observed for other hyperons in the same collision systems. A Blast-Wave function constrained by other light hadrons ($\pi $, K, $\hbox {K}_{\mathrm{S}}^0$, p, $\Lambda $) describes the shape of the $\Lambda $(1520) transverse momentum distribution up to $3.5\ \hbox {GeV}/c$ in p–Pb collisions. In the framework of this model, this observation suggests that the $\Lambda $(1520) resonance participates in the same collective radial flow as other light hadrons. The ratio of the yield of $\Lambda (1520)$ to the yield of the ground state particle $\Lambda $ remains constant as a function of charged-particle multiplicity, suggesting that there is no net effect of the hadronic phase in p–Pb collisions on the $\Lambda $(1520) yield.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The production cross section of inclusive isolated photons has been measured by the ALICE experiment at the CERN LHC in pp collisions at a centre-of-momentum energy of Formula omitted 7 TeV. The ...measurement is performed with the electromagnetic calorimeter EMCal and the central tracking detectors, covering a range of Formula omitted in pseudorapidity and a transverse momentum range of Formula omitted. The result extends the Formula omitted coverage of previously published results of the ATLAS and CMS experiments at the same collision energy to smaller Formula omitted. The measurement is compared to next-to-leading order perturbative QCD calculations and to the results from the ATLAS and CMS experiments. All measurements and theory predictions are in agreement with each other.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We present a study of the inclusive charged-particle transverse momentum ( Formula omitted) spectra as a function of charged-particle multiplicity density at mid-pseudorapidity, Formula omitted, in ...pp collisions at Formula omitted and 13 TeV covering the kinematic range Formula omitted and Formula omitted GeV/c. The results are presented for events with at least one charged particle in Formula omitted (INEL Formula omitted). The Formula omitted spectra are reported for two multiplicity estimators covering different pseudorapidity regions. The Formula omitted spectra normalized to that for INEL Formula omitted show little energy dependence. Moreover, the high- Formula omitted yields of charged particles increase faster than the charged-particle multiplicity density. The average Formula omitted as a function of multiplicity and transverse spherocity is reported for pp collisions at Formula omitted TeV. For low- (high-) spherocity events, corresponding to jet-like (isotropic) events, the average Formula omitted is higher (smaller) than that measured in INEL Formula omitted pp collisions. Within uncertainties, the functional form of Formula omitted is not affected by the spherocity selection. While EPOS LHC gives a good description of many features of data, PYTHIA overestimates the average Formula omitted in jet-like events.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The ALICE Collaboration has measured the energy dependence of exclusive photoproduction of Formula omitted vector mesons off proton targets in ultra-peripheral p-Pb collisions at a centre-of-mass ...energy per nucleon pair Formula omitted TeV. The e Formula omittede Formula omitted and Formula omitted decay channels are used to measure the cross section as a function of the rapidity of the Formula omitted in the range Formula omitted, corresponding to an energy in the Formula omittedp centre-of-mass in the interval Formula omitted GeV. The measurements, which are consistent with a power law dependence of the exclusive Formula omitted photoproduction cross section, are compared to previous results from HERA and the LHC and to several theoretical models. They are found to be compatible with previous measurements.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The measurements of the production of prompt Formula omitted, Formula omitted, Formula omitted, and Formula omitted mesons in proton-proton (pp) collisions at Formula omitted with the ALICE detector ...at the Large Hadron Collider (LHC) are reported. D mesons were reconstructed at mid-rapidity ( Formula omitted) via their hadronic decay channels Formula omitted, Formula omitted, Formula omitted, Formula omitted, and their charge conjugates. The production cross sections were measured in the transverse momentum interval Formula omitted for Formula omitted, Formula omitted for Formula omitted and Formula omitted, and in Formula omitted for Formula omitted mesons. Thanks to the higher integrated luminosity, an analysis in finer Formula omitted bins with respect to the previous measurements at Formula omitted was performed, allowing for a more detailed description of the cross-section Formula omitted shape. The measured Formula omitted-differential production cross sections are compared to the results at Formula omitted TeV and to four different perturbative QCD calculations. Its rapidity dependence is also tested combining the ALICE and LHCb measurements in pp collisions at Formula omitted. This measurement will allow for a more accurate determination of the nuclear modification factor in p-Pb and Pb-Pb collisions performed at the same nucleon-nucleon centre-of-mass energy.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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