We report the results of a search for a new vector boson (
A
′
) decaying into two dark matter particles
χ
1
χ
2
of different mass. The heavier
χ
2
particle subsequently decays to
χ
1
and an ...off-shell Dark Photon
A
′
∗
→
e
+
e
-
. For a sufficiently large mass splitting, this model can explain in terms of new physics the recently confirmed discrepancy observed in the muon anomalous magnetic moment at Fermilab. Remarkably, it also predicts the observed yield of thermal dark matter relic abundance. A detailed Monte-Carlo simulation was used to determine the signal yield and detection efficiency for this channel in the NA64 setup. The results were obtained re-analyzing the previous NA64 searches for an invisible decay
A
′
→
χ
χ
¯
and axion-like or pseudo-scalar particles
a
→
γ
γ
. With this method, we exclude a significant portion of the parameter space justifying the muon g-2 anomaly and being compatible with the observed dark matter relic density for
A
′
masses from 2
m
e
up to 390 MeV and mixing parameter
ε
between
3
×
10
-
5
and
2
×
10
-
2
.
In the field of training higher educational institution teachers, an era of significant change is beginning. For long, this area has remained the most conservative and was not noticeably subject to ...changes in society. However, the situation has changed dramatically. First of all, this is due to the rapid development of other areas of human activity, and in particular digital technologies. It is already difficult to imagine a modern society without such technologies, and the main task of a higher education teacher is precisely to train highly qualified specialists with new competencies to solve the challenges facing humanity. Strengthening the explicit link between the needs of society and the objectives of higher education is one of the prerequisites for significant changes in the field of education. The concept of training a teacher of higher education for the future today is largely determined by the development trends of digital technologies. The absence of objective reasons to assume the cessation of the use and development of digital technologies allows us to make an assumption that virtual educational worlds will appear in the foreseeable future, which will become the same familiar environment for acquiring the necessary competencies as higher schools existing in the physical world. This largely determines the relevance of the chosen research topic and determines the need for a thorough analysis of the educational technologies used in the training of teachers. The purpose of this work is, using a combination of analysis, synthesis, idealization and analogy, to generalize at the national and international levels the existing ideas about effective approaches to teaching a higher education teacher, including continuous improvement of competence in his professional field, and modern practice of using digital technologies, and also highlight the most interesting new learning experiences. The necessity of applying the so-called “integrated approach to teaching a higher education teacher” by the authors is proved. The main advantages and disadvantages of using digital technologies are highlighted. Reasonable conclusions are made on the existence of an ideal recipe for combining accumulated educational practices in the framework of traditional education and digital technology.
Hunting down the X17 boson at the CERN SPS Depero, E.; Andreev, Yu. M.; Banerjee, D. ...
European physical journal. C, Particles and fields,
12/2020, Letnik:
80, Številka:
12
Journal Article
Recenzirano
Odprti dostop
Recently, the ATOMKI experiment has reported new evidence for the excess of
e
+
e
-
events with a mass
∼
17 MeV in the nuclear transitions of
4
He, that they previously observed in measurements with
...8
Be. These observations could be explained by the existence of a new vector
X
17
boson. So far, the search for the decay
X
17
→
e
+
e
-
with the NA64 experiment at the CERN SPS gave negative results. Here, we present a new technique that could be implemented in NA64 aiming to improve the sensitivity and to cover the remaining
X
17
parameter space. If a signal-like event is detected, an unambiguous observation is achieved by reconstructing the invariant mass of the
X
17
decay with the proposed method. To reach this goal an optimization of the
X
17
production target, as well as an efficient and accurate reconstruction of two close decay tracks, is required. A dedicated analysis of the available experimental data making use of the trackers information is presented. This method provides independent confirmation of the NA64 published results
1
, validating the tracking procedure. The detailed Monte Carlo study of the proposed setup and the background estimate show that the goal of the proposed search is feasible.
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