626 research outputs found
Electron transport through interacting quantum dots
We present a detailed theoretical investigation of the effect of Coulomb
interactions on electron transport through quantum dots and double barrier
structures connected to a voltage source via an arbitrary linear impedance.
Combining real time path integral techniques with the scattering matrix
approach we derive the effective action and evaluate the current-voltage
characteristics of quantum dots at sufficiently large conductances. Our
analysis reveals a reach variety of different regimes which we specify in
details for the case of chaotic quantum dots. At sufficiently low energies the
interaction correction to the current depends logarithmically on temperature
and voltage. We identify two different logarithmic regimes with the crossover
between them occurring at energies of order of the inverse dwell time of
electrons in the dot. We also analyze the frequency-dependent shot noise in
chaotic quantum dots and elucidate its direct relation to interaction effects
in mesoscopic electron transport.Comment: 21 pages, 4 figures. References added, discussion slightly extende
Energy calibration of the NaI(Tl) calorimeter of the SND detector using events
Calibration of the three layer NaI(Tl) spherical calorimeter of the SND
detector using electron -- positron scattering events is described. Energy
resolution of for 500 MeV photons was achieved.Comment: 12 pages, Latex, 8 figures (.EPS
Some mechanisms of winter resistance in apricot flower buds in the period of ecodormancy
Received: March 27th, 2021 ; Accepted: July 6th, 2021 ; Published: August 30th, 2021 ; Correspondence: [email protected] accelerated development of flower buds during the thaw in apricots and almonds
during the ecodormancy period leads to significant damage to the flower elements during return
frosts and loss of future crops. The aim of the research was to identify the mechanisms of delay
in the rate of development of flower buds during the ecodormancy period, their relationship with
the degree of frost resistance and the timing of flowering in apricots. The following indicators of
flower buds were analyzed: the degree of exit from endodormancy, frost resistance at
temperatures of -18 °C and -31 °C, the degree of morphological development of flower elements,
the activity of α-amylases at temperatures of + 15 °C and + 60 °C, total content water,
phenolcarboxylic acids, flavonoids and free proline. A significant positive correlation was
revealed between the percentage of death of flower buds at a temperature of -18 °C and the
percentage of buds emerging from endogenous dormancy (0.64*), the percentage of death of buds
at a temperature of -31 °C and the degree of development of flower elements (0.70*), water
content and the degree of development of flower elements (0.76**), amylase activity at +60 °C
and amylase activity at +15 °C (0.76**), the content of phenolcarboxylic acids in the bark of
shoots and flower buds (0.61*). For the first time, psychrophilic forms of α-amylases have been
discovered in apricot flower buds
Search for direct production of a2(1320) and f2(1270) mesons in e+e- annihilation
A search for direct production of C-even resonances a2(1320) and f2(1270) in
e+e- annihilation was performed with SND detector at VEPP-2M e+e- collider. The
upper limits of electronic widths of these mesons were obtained at 90%
confidence level:
Gamma(a2(1320) \to e+e-) < 0.56 eV,
Gamma(f2(1270) \to e+e-) < 0.11 eV.Comment: 6 pages, 5 figures, 1 table. Submitted to Phys. Lett.
Effect of quantum noise on Coulomb blockade in normal tunnel junctions at high voltages
We have investigated asymptotic behavior of normal tunnel junctions at
voltages where even the best ohmic environments start to look like RC
transmission lines. In the experiments, this is manifested by an exceedingly
slow approach to the linear behavior above the Coulomb gap. As expected on the
basis of the quantum theory taking into account interaction with the
environmental modes, better fits are obtained using 1/sqrt{V}- than 1/V-
dependence for the asymptote. These results agree with the horizon picture if
the frequency-dependent phase velocity is employed instead of the speed of
light in order to determine the extent of the surroundings seen by the
junction.Comment: 9 pages, 4 figures, submitted to Phys. Rev.
Radiative decays of light vector mesons
The new data on radiative decays into
from SND experiment at VEPP-2M
collider are presented.Comment: 5 pages, 2 figures, talk given at 8th International Conference on
Hadron Spectroscopy (HADRON 99), Beijing, China, 24-28 Aug 199
Experimental study of the e+e- -> pi0 gamma process in the energy region sqrt(s)=0.60-0.97 GeV
Results of the study of the e+e-->pi0 gamma process with SND detector at
VEPP-2M collider in the c.m.s. energy range sqrt(s)=0.60-0.97 GeV are
presented. Using 36513 selected events corresponding to a total integrated
luminosity of 3.4 pb^-1 the e+e-->pi0 gamma cross section was measured. The
energy dependence of the cross section was analyzed in the framework of the
vector meson dominance model. The data are well described by a sum of
phi,omega,rho0->pi0 gamma decay contributions with measured decay
probabilities: Br(omega->pi0 gamma)=(9.34+-0.15+-0.31)% and Br(rho0->pi0
gamma)=(5.15+-1.16+-0.73)*10^-4 . The rho-omega relative interference phase is
phi(rho,omega}=(-10.2+-6.5+-2.5) degree
New experimental data for the decays and from SND detector
The processes and have been
studied with SND detector at VEPP-2M collider in the vicinity of
resonance. The branching ratios and were obtained.Comment: 5 pages, 4 figures, talk given at 8th International Conference on
Hadron Spectroscopy (HADRON 99), Beijing, China, 24-28 Aug 199
New Data from SND Detector in Novosibirsk
The current status of experiments with SND detector at VEPP-2M e^+e^-
collider in the energy range 2E_0=400-1400 MeV and recent results of data
analysis for , and decays and e^+e^- annihilation into
hadrons are presented.Comment: 7 pages, 8 figures, Latex2e, uses espcrc1.sty. Talk given at 8th
International Conference on Hadron Spectroscopy (HADRON 99), Beijing, China,
24-28 Aug 199
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