We report results from an updated study of the suppressed decays B- to D K- and B- to D* K- followed by D to K+pi-, where D(*) indicates a D(*)0 or an anti-D(*)0 meson, and D* decays to D pi0 or D ...gamma. These decays are sensitive to the CKM unitarity triangle angle gamma, due to interference between the b to c transition B- to D(*)0K- followed by the doubly Cabibbo-suppressed decay D0 to K+pi-, and the b to u transition B- to anti-D(*)0K- followed by the Cabibbo-favored decay anti-D0 to K+pi-. We also report an analysis of the decay B- to D(*)pi- with the D decaying into the doubly Cabibbo-suppressed mode D to K+pi-. Our results are based on 467 million Upsilon (4S) to B anti-B decays collected with the BaBar detector at SLAC. We measure the ratios R(*) of the suppressed (K+pi-_D K-/pi-) to favored (K-pi+_D K-/pi-) branching fractions as well as the CP asymmetries A(*) of those modes. We see indications of signals for the B- to D K- and B- to D*K-, D*->D pi0 suppressed modes, with statistical significances of 2.1 and 2.2 sigma, respectively, and we measure: R_{DK} = (1.1\pm 0.6 \pm 0.2)\times 10^{-2}, A_{DK} = -0.86 \pm 0.47 \ ^{+0.12}_{-0.16}, R*_{(D pi0)K} = (1.8\pm 0.9 \pm 0.4)\times 10^{-2}, A*_{(D pi0)K} = +0.77 \pm 0.35\pm 0.12, R*_{(D gamma)K} = (1.3\pm 1.4\pm 0.8 )\times 10^{-2}, A*_{(D gamma)K} = +0.36 \pm 0.94\ ^{+0.25}_{-0.41}, where the first uncertainty is statistical and the second is systematic. We use a frequentist approach to obtain the magnitude of the ratio r_B = |A(B- to anti-D0 K-) / A(B- to D0K-)|= (9.5^{+5.1}_{-4.1})%, with r_B<16.7% at 90% confidence level. In the case of B- to D* K- we find r*_B = |A(B^- to anti-D*0 K-)/A(B- to D*0 K-)|=(9.6^{+3.5}_{-5.1})%, with r*_B<15.0% at 90% confidence level.
Ilmenite-type crystals find a variety of technological applications due to their intriguing physical properties. We present the results of the lattice dynamics studies of honeycomb antiferromagnetic ...ilmenite CoTiO3 single crystal by the complementary polarized infrared, Raman, and dielectric spectroscopic techniques that are supplemented by the DFT calculations. The symmetries and frequencies of all predicted infrared- and Raman-active phonons were uniquely identified. Furthermore, it was found that the dielectric permittivity demonstrates distinct changes below antiferromagnetic ordering temperature in zero magnetic field due to the spontaneous magnetodielectric effect. Our results establish the solid basis for further investigations and more deep understanding of the coupling of phonons with spins and magnetic excitations, as well as their involvement in other physical phenomena in this promising material.
•Single crystal of ilmenite CoTiO3 was grown by optical floating zone technique.•The lattice dynamics were studied by infrared, Raman and dielectric spectroscopies and supplemented by the DFT calculations.•All infrared- and Raman-active phonons were uniquely identified.•The spontaneous magnetodielectric effect at antiferromagnetic ordering in zero magnetic field was observed.
Abstract Understanding spin-lattice interactions in antiferromagnets is a critical element of the fields of antiferromagnetic spintronics and magnonics. Recently, coherent nonlinear phonon dynamics ...mediated by a magnon state were discovered in an antiferromagnet. Here, we suggest that a strongly coupled two-magnon-one phonon state in this prototypical system opens a novel pathway to coherently control magnon-phonon dynamics. Utilizing intense narrow-band terahertz (THz) pulses and tunable magnetic fields up to μ 0 H ext = 7 T, we experimentally realize the conditions of magnon-phonon Fermi resonance in antiferromagnetic CoF 2 . These conditions imply that both the spin and the lattice anharmonicities harvest energy from the transfer between the subsystems if the magnon eigenfrequency f m is half the frequency of the phonon 2 f m = f ph . Performing THz pump-infrared probe spectroscopy in conjunction with simulations, we explore the coupled magnon-phonon dynamics in the vicinity of the Fermi-resonance and reveal the corresponding fingerprints of nonlinear interaction facilitating energy exchange between these subsystems.
Spherical neutral detector for VEPP-2M collider Achasov, M.N; Aulchenko, V.M; Baru, S.E ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2000, Letnik:
449, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The Spherical Neutral Detector (SND) operates at VEPP-2M collider in Novosibirsk studying e
+e
− annihilation in the energy range up to 1.4
GeV. Detector consists of a fine granulated spherical ...scintillation calorimeter with 1632 NaI(Tl) crystals, two cylindrical drift chambers with 10 layers of sense wires, and a muon system made of streamer tubes and plastic scintillation counters. The detector design, performance, data acquisition and processing are described.
Abstract
We examined the assembly of DNA G-quadruplexes (G4s) into higher-order structures using atomic force microscopy, optical and electrophoretic methods, NMR spectroscopy and molecular modeling. ...Our results suggest that parallel blunt-ended G4s with single-nucleotide or modified loops may form different types of multimers, ranging from stacks of intramolecular structures and/or interlocked dimers and trimers to wires. Decreasing the annealing rate and increasing salt or oligonucleotide concentrations shifted the equilibrium from intramolecular G4s to higher-order structures. Control antiparallel and hybrid G4s demonstrated no polymorphism or aggregation in our experiments. The modification that mimics abasic sites (1′,2′-dideoxyribose residues) in loops enhanced the oligomerization/multimerization of both the 2-tetrad and 3-tetrad G4 motifs. Our results shed light on the rules that govern G4 rearrangements. Gaining control over G4 folding enables the harnessing of the full potential of such structures for guided assembly of supramolecular DNA structures for nanotechnology.
Liver is the most common organ to get injured in cases of blunt force trauma to the abdomen (BFTA). It is the 2nd commonest organ after brain to sustain injuries out of all the trauma related ...fatalities. However, the literature about contre-coup injuries to the liver due to BFTA is scarce in-spite of the high mortality rates seen out of injury to this particular organ.
The authors intended to systematize the characteristic morphogenesis of the contre-coup injuries of the liver on the basis of the patho-mechanics involved in various types of BFTA.
One hundred and sixty three cases of BFTA were identified, and interpretation was attempted for the contre-coup rupture of the liver seen in twenty out of all the trauma related fatalities that presented for post-mortem examination during the study period. However, the mechanics of the pattern of the rupture injuries to the liver were indiscernible. This motivated the authors to conduct the comparative characterization of injuries to the liver by experimental simulation of BFTA after necessary permission via inflicting pre-calculated forces on unclaimed cadavers.
The patterns of contre-coup rupture/s of liver were established in all the twenty out of one sixty-three cases of BFTA. The rupture depicted patterns of injury in the situations of - 1) strong hits with a limited surface trauma, 2) very strong hits with a generalized surface trauma, 3) and collision with a solid surface resulting due to fall onto the side of the abdomen. The causative mechanism discerned was deformation of the liver, followed by its parenchymal rupture due to the shear and strain types of force/s consequent upon tissue compression. The minimum force and energy of impact required for the liver to rupture was estimated to be 2000 N and 141.5 J.
This series of the simulation experiments revealed two variants of liver rupture in the contre-coup impact zone. The pattern of injury was maintained in cases, those studied at post-mortem examinations, but the relief ruptures were found to vary depending upon the overall mechanics of the traumatic forces involved in the simulation experiments performed on the cadavers. The anti-shock ruptures were formed during shock trauma, and shockproof ruptures were not seen in cases of underlying compressive forces. The morphogenetic characterization of the relief rupture surface of the liver was also delineated in relation to its surface orientation to the spine on the basis of the terms “large” and “very large” depicting the quantum of force/s delivered out of an impact or blow.
Magneto-optical glass materials with large Verdet constants at 2 μm have attracted increasing attention due to the significant advances of novel lasers operating at this wavelength region. In this ...paper, 13Al2O3-21B2O3-35.4SiO2-(30.6-X)Er2O3-XDy2O3 glasses have been synthesized, and their physical, optical, and magneto-optical properties were studied for making Faraday devices at 2 μm. A Verdet constant of as high as −5.9 rad/(T*m) at 1950 nm was measured with a 13Al2O3-21B2O3-35.4SiO2-30.6Dy2O3 glass. The temperature difference between crystallization and glass transition of 150 °C and the synthesis temperature of below 1500 °С make this glass very promising for making magneto-optical devices for 2 μm applications.
In the last two decades copper metaborate CuB
2
O
4
with a unique noncentrosymmetric crystal structure has become the subject of active research due to its unusual magnetic and optical properties. ...We consider the propagation and absorption of light in CuB
2
O
4
based on the solution of Maxwell’s equations. We present an overview of the main results on the investigation of the phonon spectrum using infrared and Raman spectroscopy. Studies in the region of electronic transitions in Cu
2+
ions in the crystal field have allowed the separation of contributions to the optical absorption from copper ions in inequivalent positions. A splitting of zero-phonon absorption lines in a magnetic field has been detected, and these results have received a theoretical explanation in terms of the exciton model. A rich structure of exciton–magnon states has been observed in the photoluminescence spectra. We have carried out a spectroscopic study of the optical second harmonic generation in the region of excitonic transitions, which has allowed the contribution of the toroidal moment and the Fano resonance to the observed signals to be revealed.
The interaction of light with spins in a Heisenberg antiferromagnet with a negligibly low magnetic anisotropy as in RbMnF
3
has been theoretically analyzed. In particular, an optical pump–probe ...experiment, where coherent terahertz magnons are excited by short pump laser pulses in the antiferromagnet and are then detected by a probe pulse delayed with respect to the pump pulse, has been simulated. It has been shown that the giant increase in the intensity of excitation of terahertz magnons under the influence of the inverse Cotton–Mouton effect occurs near parametric resonance, i.e., in the parametric instability region.
Experimental results on temperature dependences of the low-frequency dielectric permittivity of the group of magnetic fluoroperovskites with different crystal and magnetic structures are presented. ...Orthorhombic NaCoF
3
and NaNiF
3
, cubic RbFeF
3
, hexagonal RbNiF
3
and tetragonal K
2
CoF
4
and K
2
NiF
4
were investigated. The analysis of experimental results in combination with those of our previous studies of other fluoroperovskites was carried out taking into account the influence of the spontaneous magnetodielectric effect on lattice dynamics. It revealed the role of the spin-phonon coupling and the anharmonic contribution, which leads an increase of dielectric permittivity at heating, and contribution of the hidden structural instability manifested as an increase of the dielectric permittivity at cooling. It was established that the relative contributions of these three main mechanisms to the temperature dependence of dielectric permittivity are significantly different in all fluoroperovskites under study but they are well correlated with the tolerance factor
t
, which characterizes a relation between ionic radii and is a measure of stability of AMF
3
perovskite crystal structure. The obtained results and their analysis reliably demonstrate that the low-frequency dielectric spectroscopy is a highly sensitive method to study particular features of the lattice dynamics of fluoroperovskites at magnetic and structural phase transitions.
PDF
