In this paper, we present a feasibility study of the first measurement of the longitudinal polarization of a muon from the
-lepton decay to extract the Michel parameter
at the future Super Charm-Tau ...Factory (SCTF). The expected number of
events on the full SCTF data was estimated, possible background processes were studied, and methods of their suppression were suggested. Statistical accuracy was estimated to be
, which enables a new verification of the Standard Model at high precision level.
A method is suggested that allows the first measurement of the polarization of muons from τ-lepton decays at the Super charm-tau Factory. To measure the polarization, it is proposed to use muons ...decayed in flight in the drift chamber of the detector, when both tracks, mother and daughter, were reconstructed by the reconstruction program. The method is based on the correlation between the muon spin and daughter electron momentum. We used a Monte Carlo simulation with the Super charm-tau Factory detector parameters to estimate the number of decayed-in-flight muons. Possible background processes were studied and methods for their suppression were proposed. The expected statistical uncertainty for muon polarization measurement is about 2%.
A
bstract
This paper provides a detailed description of the method for the first direct measurement of all Michel parameters in the
τ
−
→ μ
−
ν
¯
μ
ν
τ
decay related to the polarization of the ...daughter muon. An application of the suggested method in the existing and future experiments at
e
+
e
−
colliders is considered. We have performed a feasibility study for the future Super Charm-Tau Factory and Belle II experiments. For the first one, the sensitivity to the Michel parameters
ξ
′,
ξ
′′,
η
′′,
α
′
/A
, and
β
′
/A
is estimated. For the latter, only one Michel parameter,
ξ
′, for which the sensitivity is maximum, is considered.
A method for measuring all Michel parameters describing the daughter muon polarization in the
decay, i.e.,
,
,
,
, and
, is discussed. The application of the method to the future Super Charm-Tau ...Factory experiment is considered. The statistical uncertainties expected by the full data statistics (10 ab
–1
) are estimated as
,
,
,
, and
. On their basis, upper limits on the coupling constants of interactions beyond the Standard Model are estimated. The New Physics scenario is considered, which can be reliably detected if the estimated accuracy of the
parameter measurement is achieved.
A
bstract
This paper provides a detailed description of the method for the first direct measurement of all Michel parameters in the
τ
−
→ μ
−
$$ \overline{\nu} $$
ν
¯
μ
ν
τ
decay related to the ...polarization of the daughter muon. An application of the suggested method in the existing and future experiments at
e
+
e
−
colliders is considered. We have performed a feasibility study for the future Super Charm-Tau Factory and Belle II experiments. For the first one, the sensitivity to the Michel parameters
ξ
′,
ξ
′′,
η
′′,
α
′
/A
, and
β
′
/A
is estimated. For the latter, only one Michel parameter,
ξ
′, for which the sensitivity is maximum, is considered.
Abstract This paper provides a detailed description of the method for the first direct measurement of all Michel parameters in the τ − → μ − ν ¯ $$ \overline{\nu} $$ μ ν τ decay related to the ...polarization of the daughter muon. An application of the suggested method in the existing and future experiments at e + e − colliders is considered. We have performed a feasibility study for the future Super Charm-Tau Factory and Belle II experiments. For the first one, the sensitivity to the Michel parameters ξ′, ξ′′, η′′, α′/A, and β′/A is estimated. For the latter, only one Michel parameter, ξ′, for which the sensitivity is maximum, is considered.
Regardin the data of Andropoulos et al. perfusion volume speed should be individually chosen based on deep oxymetria and transcranial dopplerography 1.
Luciani et al. showed advantages of cerebral ...and myocardial perfusion under moderate hypothermia in comparison to standard perfusion 2. They showed that standard perfusion and low cerebro-myocardial flow are predictors of myocardial dysfunction.
We eventually have come to a decision to abstain from cardioplegia and hypothermia that way, first, removing myocardial dysfunction risk factors; second, shortening perfusion time, and third, preserving brain flow self-regulation.
After obtaining the ethics committee approval we prospectively analyzed results of neonatal aortic arch reconstruction in our clinic since July 2015. In this period of time we performed 36 operations for hypoplastic aortic arch in newborn. All the procedures were performed in normothermic (above 34 C) antegrade regional cerebral perfusion and coronary perfusion. We used transcranial doppler, deep cerebral oximetry and ECG to assess perfusion efficacy.
Mean age was 12.3 (6-23) days, weight – 3.2 (2.4-4.4) kg. Perfusion time was 70 (61.5;83.5) minutes, selective perfusion (antegrade regional cerebral and coronary) time was 28 (24;33.5) minutes. Perfusion flow was 118.5 (106;131.5) ml/kg/minute. Middle cerebral artery flow was 28 (22.5;33.25) cm/s on the right and 24 (18;27) cm/s on the left. ECG and deep cerebral oxygenation was stable through whole perfusion. Four (13.8%) patients required delayed sternal closure. In 6 hours after the operation vasoactive inotropic score was 10 (5;14.5), in 48 hours after the operation it was 5 (3;10). Lactate level was 3.2 (2.8;4.3) mmol/L in 6 hours after the procedure and 2.2 (1.85-3) mmol/L in 48 hours. Creatine phosphokinase (CPK) and creatine phosphokinase myocardial band (CPKMB) levels were 445.5 (302.75;632.5) U/L and 64 (51.25;96.5) U/L, respectively, in 6 hours and decreased to 126 (97;233) U/L and 50 (23;96) U/L in 48 hours after the operation. Troponin I level in 6 hours was 1.35 (0.95;1.5) ng/ml and in 48 hours – 0.62 (0.55;0.76) ng/ml. All patients regained consciousness in 24-48 hours after the operation with no neurologic deficiency. Mean ventilation time was 4.4 (1-11) days, mean ICU stay time was 5.9 (2-22) days. Hospital mortality was 2.8% (1 patient).
Normothermic antegrade regional cerebral perfusion with coronary perfusion is a safe and decent technique in neonatal aortic arch reconstruction. It allows to avoid such detrimental risk factors as circulatory arrest, hypothermia, extensive perfusion and cardioplegia.
A procedure for calculating the temperature fields in water-cooled piercer mandrels is developed. The results of calculations of a heat conduction equation by the finite element method and the method ...of finite differences are compared. High-temperature EP745 alloy is proposed as a material for piercer mandrels. The thermally stressed state of water-cooled piercer mandrels is determined.
We report the first measurement of the Michel parameter ξ′ in the τ−→μ−¯νμντ decay with a new method proposed just recently. The measurement is based on the reconstruction of the τ−→μ−¯νμντ events ...with subsequent muon decay in flight in the Belle central drift chamber. The analyzed data sample of 988 fb−1 collected by the Belle detector corresponds to approximately 912×106 τ+τ− pairs. We measure ξ′=0.22±0.94(stat)±0.42(syst), which is in agreement with the standard model prediction of ξ′=1. Statistical uncertainty dominates in this study, being a limiting factor, while systematic uncertainty is well under control. Our analysis proved the practicability of this promising method and its prospects for further precise measurement in future experiments.
PDF
