Spin-dependent energy distribution of B-hadrons from polarized top decays considering the azimuthal correlation rate

In our previous work, we studied the polar distribution of the scaled energy of bottom-flavored hadrons from polarized top quark decays $t(\uparrow)\rightarrow W^++b(\rightarrow X_b)$, using two different helicity coordinate systems. Basically, the energy distributions are governed by the unpolarized, polar and azimuthal rate functions which are related to the density matrix elements of the decay $t(\uparrow)\rightarrow W^++b$. Here we present, for the first time, the analytical expressions for the ${\cal O}(\alpha_s)$ radiative corrections to the differential azimuthal decay rates of the partonic process $t(\uparrow)\rightarrow b+W^+(+g)$ in two helicity systems, which are needed to study the azimuthal distribution of the energy spectrum of the B-hadron produced in polarized top quark decays. Our predictions of the hadron energy distributions enable us to deepen our knowledge of the hadronization process and to determine the polarization states of top quarks

Heavy quark fragmentation functions at next-to-leading perturbative QCD

It is well-known that the dominant mechanism to produce hadronic bound states with large transverse momentum is fragmentation. This mechanism is described by the fragmentation functions (FFs) which are the universal and process-independent functions. Here, we review the perturbative FFs formalism as an appropriate tool for studying these hadronization processes and detail the extension of this formalism at next-to-leading order (NLO). Using the Suzuki's model, we calculate the perturbative QCD FF for a heavy quark to fragment into a S-wave heavy meson at NLO. As an example, we study the LO and NLO FFs for a charm quark to split into the S-wave $D$-meson and compare our analytic results both with experimental data and well-known phenomenological models

How Should Governments Address High Levels of Natural Radiation and Radon--Lessons from the Chernobyl Nuclear Accident and Ramsar, Iran

The authors discuss the high levels of natural background radiation in Ramsar, Iran, and offer data indicating that this has had little effect on the health of Ramsar\u27s inhabitants. The authors then examine the implications their research could have for public health policy

Indirect search for light charged Higgs bosons through the dominant semileptonic decays of top quark t→b(→B/D+X)+H+(→τ+ντ)t\to b(\to B/D+X)+H^+(\to \tau^+\nu_\tau)

In this work we introduce a new channel to indirect search for the light charged Higgs bosons, which are predicted in several extensions of the standard model (SM) such as the two-Higgs-doublet models (2HDMs). We calculate the ${\cal O}(\alpha_s)$ QCD radiative corrections to the energy distribution of bottom- and charmed-flavored hadrons ($B/D$) produced in the dominant decays of the polarized top quark in the 2HDM, i.e. $t(\uparrow)\longrightarrow b(\to B/D+\text{jet})+H^+(\to \tau^+\nu_\tau)$. %This analysis is studied in a specific helicity coordinate system where the polarization vector of the top quark is evaluated with respect to the momentum direction of the bottom quark. Generally, the energy distribution of hadrons is governed by the unpolarized rate and the polar and the azimuthal correlation functions which are related to the density matrix elements of the decay $t(\uparrow)\rightarrow bH^+$. In our proposed channel, any deviation of the $B/D$-meson energy spectrum from its corresponding SM predictions can be considered as a signal for the existence of charged Higgs at the LHC. We also calculate, for the first time, the azimuthal correlation rate $\Gamma_\phi$ at next-to-leading order which vanishes at the Born level.Comment: 10 pages, 5 figures, published in NPB 932 (2018) 50

Speed Roughness Control of an SI Engine Using Fuzzy Self Tuning Method

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Protective role of cyclosporine on the model simulated the rotational nodal arrhythmia (AVNRT) by using extracellular field potential recordings of isolated atrioventricular-node of rabbit

Introduction: Recent studies have shown acute cardioprotective effects of cyclosporine. The aim of the present study was to determine the protective role of cyclosporine on the model simulated the rotational nodal arrhythmia (AVNRT) by using extracellular field potential recordings of isolated atrioventricular-node (AV-node) of rabbit. Methods: This study was performed on isolated double-perfused AV-node of male New Zealand rabbits (1.5-2.5 kg) in one group (n=7). Basic and rate-dependent stimulation protocols (recovery, facilitation, fatigue) and arrhythmia threshold (index of refractoriness) and % Gap incidence were measured for assessment of electrophysiological properties of the AV- node. All stimulation protocols were repeated in control step and in the presence of various cumulative concentrations of cyclosporine (0.5 - 10 μm). Results: Cyclosporine prolonged the effective refractory period from 114.3±7.9 to 142±7.3 msec at the concentration of 10 μm. It also prolonged the functional refractory period from 162±3.3 to 178.6±5 msec and increased the time of Wenckebach at the concentrations of 5 - 10 μM. Various concentrations of cyclosporine increased fatigue and reached a significant level at 10 μm. Gap incidence was 82%, 16.6% and 20% in the control and treatments with 0.5 and 10 μm of cyclosporine, respectively. Conclusion: Block of MPTP by cyclosporine caused inhibition of basic and rate-dependent properties of atrioventricular node. Cyclosporine, by raising the threshold of arrhythmia, could be possibly considered as an anti- AVNRT drug

Heat transfer at the interface of graphene nanoribbons with different relative orientations and gaps

Because of their high thermal conductivity, graphene nanoribbons (GNRs) can be employed as fillers to enhance the thermal transfer properties of composite materials, such as polymer-based ones. However, when the filler loading is higher than the geometric percolation threshold, the interfacial thermal resistance between adjacent GNRs may significantly limit the overall thermal transfer through a network of fillers. In this article, reverse non-equilibrium molecular dynamics is used to investigate the impact of the relative orientation (i.e., horizontal and vertical overlap, interplanar spacing and angular displacement) of couples of GNRs on their interfacial thermal resistance. Based on the simulation results, we propose an empirical correlation between the thermal resistance at the interface of adjacent GNRs and their main geometrical parameters, namely the normalized projected overlap and average interplanar spacing. The reported correlation can be beneficial for speeding up bottom-up approaches to the multiscale analysis of the thermal properties of composite materials, particularly when thermally conductive fillers create percolating pathways