A project of a Super Charm-Tau factory is being developed at the Budker Institute of Nuclear Physics (Siberian Branch, Russian Academy of Sciences) in Novosibirsk. The electron-positron collider to ...be employed will operate at c.m. energies in the range between 2 and 5 GeV at an unprecedentedly high luminosity of 10
35
cm
−2
s
−1
with a longitudinal electron polarization at the beam-interaction point. The main objective of experiments at the Super Charm-Tau factory is to study processes involving the production and properties of charmed quarks and tau leptons. A high luminosity of this setup will make it possible to obtain a statistical data sample that will be three to four orders of magnitude vaster than that from any other experiment performed thus far. Experiments at this setup are assumed to be sensitive to effects of new physics beyond the Standard Model. Investigations to be carried out at the Super-Charm-Tau factory will supplement future experiments at Super-
B
factories under construction in Italy and in Japan.
Charge asymmetry in decays B →DD¯K Bondar, A. E.; Milstein, A. I.
The journal of high energy physics,
12/2020, Letnik:
2020, Številka:
12
Journal Article
Recenzirano
Odprti dostop
A
bstract
We discusses the charge asymmetry in
B →
D
D
¯
K
decays with an invariant mass of the
D
D
¯
pair near the Ψ(3770) resonance. Unlike Ψ(3770) decays in
e
+
e
−
annihilation, in
B
+
decays the ...probability of
D
0
D
¯
0
production is almost three times higher than
D
+
D
−
. In
B
0
decays, the ratio of these probabilities will be opposite. The effect is explained by the fact that, in
B
-meson decays, the
D
D
¯
pair is produced in a superposition of isoscalar and isovector states, and only in combination with
K
-mesons the total state has 1
/
2 isospin. We present a simple model in which the interference of the nonresonant isovector amplitude with the resonant isoscalar amplitude explains the experimental data.
A method for measuring cross sections at
colliders for the case where the center-of-mass frame of colliding particles moves in the laboratory frame is proposed. Within this method, the energy ...dependence of the cross section is extracted from the angular distribution of interaction products. The method applied to the
process is found to be sensitive. This method provides the possibility of studying the fine structure of the cross section near the threshold at scales much less than the energy spread of the beams used. Similar measurements may be implemented in experiments at the Super Charm-Tau Factory.
A
bstract
Model estimates are obtained for the influence of Coulomb effects on the ratio of the cross sections for the production of charged and neutral
B
B
¯
and
B
*
B
¯
*
pairs in
e
+
e
−
...annihilation. It is shown that the difference between the masses of charged and neutral mesons obtained under the assumption that this ratio is constant on a scale of the order of the beam energy spread can differ from the true one by
δM
∼ 0
.
03 MeV at the energy of Υ(5
S
) and by
δM ∼
0
.
4 MeV at the energy of Υ(4
S
). Thus, the errors given in the PDG for the difference between the masses of charged and neutral
B
mesons, based on the results obtained at the energy of Υ(4
S
), are strongly underestimated. Similar measurements at the energy of Υ(5
S
) will have an order of magnitude smaller systematic shift for the mass difference. This circumstance should be taken into account when planning future experiments at the
B
factory in KEK.
The cross section of the process e + e − → π + π − has been measured in the center-of-mass energy range from 0.32 to 1.2 GeV with the CMD-3 detector at the electron-positron collider VEPP-2000. The ...measurement is based on an integrated luminosity of about 88 pb − 1 , of which 62 pb − 1 represent a complete dataset collected by CMD-3 at center-of-mass energies below 1 GeV. In the dominant region near the ρ resonance a systematic uncertainty of 0.7% was achieved. The implications of the presented results for the evaluation of the hadronic contribution to the anomalous magnetic moment of the muon are discussed. Published by the American Physical Society 2024
Patients with hereditary spherocytosis (HS) are characterized by having an increased risk for thrombosis. An early manifestation of thrombotic complications can occur even in childhood, especially ...after surgery. Hypercoagulability can be associated with hemolytic crises.
The aim of this study was to investigate the hemostatic state in children with HS using global hemostasis assays.
The hemostatic status of 62 children (38 boys and 24 girls; age range: 0.5 to 17 years) with HS during and without hemolytic crisis was assessed using clotting times (APTT, TT, and PR), fibrinogen and D-dimer levels, and global hemostasis, thromboelastography (TEG) and thrombodynamics (TD) assays. One hundred and two healthy children undergoing annual medical examination were enrolled as a control group.
TEG and TD parameters were increased in the children with HS compared to the control group (60 ± 5 mm vs. 53 ± 4 mm, p < 0.05 for TEG maximum amplitude; 28 ± 3 μm/min vs. 24 ± 2 μm/min, p < 0.05 for TD clot growth rate), while APTT, TT and PR were not significantly different between the two groups. Patients with HS were divided into 2 groups: those during hemolytic crisis (28 patients) and those without hemolytic crisis (34 patients). TEG and TD parameters were increased in those during hemolytic crisis compared to the steady state HS group (62 ± 5 mm vs. 57 ± 4 mm, p < 0.05 for TEG maximum amplitude; 31 ± 4 μm/min vs. 26 ± 3 μm/min, p < 0.05 for TD clot growth rate). The D-dimer levels were increased in 4 HS patients, for whom the activation of blood clotting was noted. Fibrinogen levels were decreased in patients with HS compared to the control group (2.1 ± 0.4 mg/ml vs. 2.6 ± 0.4 mg/ml, p < 0.05). Other tests were within the reference ranges for both groups.
The global hemostasis tests TEG and TD revealed hypercoagulability in patients with HS. More dramatic changes were observed in patients experiencing a hemolytic crisis.
•Hereditary spherocytosis is a congenital disorder associated with hypecoagulability•Patients may have hemolytic crisis associated with thrombotic complications; however, thrombosis in children is rather rare•Conventional clotting times are not useful for diagnosing the coagulation system in patients with hereditary spherocytosis•The global tests thromboelastography and thrombodynamics revealed hypercoagulability in hereditary spherocytosis
A new ion identification method for accelerator mass spectrometry on the basis of measuring ion track ranges is proposed. A low pressure time projection chamber (TPC) with charge readout by means of ...a thick gas electron multiplier (THGEM) was developed for testing this method. Tracks of alpha particles from various radioactive sources were successfully recorded by this TPC. In particular, their track ranges were measured to a high precision of about 2
. A simulation was performed, and it was shown that track range measurements would permit efficiently separating isobaric boron and beryllium ions (at a level of ten standard deviations). It is expected that this method will be used in the accelerator mass spectrometry facility in Novosibirsk for dating geological objects—in particular, for the geochronology of Cenozoic era.
For the first time, the chymosin gene (
CYM
) of a maral was characterized. Its exon/intron organization was established using comparative analysis of the nucleotide sequence. The
CYM
mRNA sequence ...encoding a maral preprochymosin was reconstructed. Nucleotide sequence of the
CYM
maral mRNA allowed developing an expression vector to ensure production of a recombinant enzyme. Recombinant maral prochymosin was obtained in the expression system of
Escherichia
coli
strain BL21 (DE3). Total milk-coagulation activity (MCA) of the recombinant maral chymosin was 2330 AU/ml. The recombinant maral prochymosin relative activity was 52955 AU/mg. The recombinant maral chymosin showed 100-81% MCA in the temperature range 30-50°C, thermal stability (TS) threshold was 50°C, and the enzyme was completely inactivated at 70°C. Preparations of the recombinant chymosin of a single-humped camel and recombinant bovine chymosin were used as reference samples. Michaelis–Menten constant (
K
m
), turnover number (
k
cat
), and catalytic efficiency (
k
cat
/K
m
) of the recombinant maral chymosin, were 1.18 ± 0.1 µM, 2.68 ± 0.08 s
−1
and 2.27± 0.10 µm M
−1
·s
−1
, respectively.
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