Polarization method for controlling a sign of electromagnetically-induced transparency/absorption resonances

We propose a new easy method to control a sign of the subnatural resonances of electromagnetically-induced transparency and absorption in the Hanle configuration under counterpropagating light waves. The analytical results for a three-level atomic Λ-scheme are corroborated by numerical calculations for various atomic transitions. The results can be applied in nonlinear optics, optical communications and magnetometry.     

Scattering of light by a periodic structure in the presence of randomness IV. Limit of detection by curve fitting

In the context of scattering of light, we determine the extent of randomness within which a hidden periodic part can still be detected. The detection is carried out using a technique called the extended matched filtering, first introduced by us in this context. The earlier prediction, before our technique was introduced, had placed the limit of detection, by intensity measurements alone, at (r ₀/Λ) ∼ 0.33, where r₀ is the coherence length of light for scattering by the rough part of the surface and Λ is the wavelength of the periodic part of the surface. In our earlier works we have shown that by intensity measurements alone, the limit of detection can be taken to a much lower value of (r ₀/Λ), when the extended matched filtering method is employed. In this paper we follow the extended matched filtering method, and try to reach the lowest possible value of detection in (r ₀/Λ) by fitting the data to a polynomial. It is concluded by our numerical work that the lowest possible limit for detection from intensity measurements alone is (r ₀/Λ) = 0.11.     

Semi-empirical formula for Λ-binding energies in ground states of light hypernuclei

Starting with a Λ-nucleus potential, we have obtained a semi-empirical formula, which gives a fairly satisfactory account of the ground state Λ-binding energy of light hypernuclei, if the very light nuclei are ignored.     

Cluster model of s- and p-shell ΛΛ hypernuclei

The ΛΛ binding energy (B _ΛΛ) of the s- and p-shell hypernuclei are calculated variationally in the cluster model and multidimensional integrations are performed using Monte Carlo. A variety of phenomenological Λ-core potentials consistent with the Λ-core energies and a wide range of simulated s-state ΛΛ potentials are taken as input. The B _ΛΛ of _ΛΛ⁶He is explained and _ΛΛ⁵He and _ΛΛ⁵H are predicted to be particle stable in the ΛΛ-core model. The results for s-shell hypernuclei are in excellent agreement with those of non-VMC calculations. The _ΛΛ¹⁰Be in ΛΛαα model is overbound for combinations of ΛΛ and Λα potentials. A phenomenological dispersive three-body force, V _Λαα, consistent with the B _Λ of _Λ⁹Be in the Λαα model underbinds _ΛΛ¹⁰Be. The incremental ΔB _ΛΛ values for the s- and p-shell cannot be reconciled, consistent with the finding of earlier analyses.      

Scattering of light by a periodic structure in the presence of randomness VII: Application of statistical detection test

Detection of periodic structures, hidden in random surfaces has been addressed by us for some time and the ‘extended matched filter’ method, developed by us, has been shown to be effective in detecting the hidden periodic part from the light scattering data in circumstances where conventional data analysis methods cannot reveal the successive peaks due to scattering by the periodic part of the surface. It has been shown that if r ₀ is the coherence length of light on scattering from the rough part and Λ is the wavelength of the periodic part of the surface, the extended matched filter method can detect hidden periodic structures for (r ₀/Λ) ≥ 0.11, while conventional methods are limited to much higher values ((r ₀/Λ) ≥ 0.33). In the method developed till now, the detection of periodic structures involves the detection of the central peak, first peak and second peak in the scattered intensity of light, located at scattering wave vectors v _x = 0, Q, 2Q, respectively, where Q = 2Gp/Λ, their distinct identities being obfuscated by the fact that the peaks have width Δv _x = 2Gp/r ₀ ≫ Q. The relative magnitudes of these peaks and the consequent problems associated in identifying them is discussed. The Kolmogorov-Smirnov statistical goodness test is used to justify the identification of the peaks. This test is used to ‘reject’ or ‘not reject’ the null hypothesis which states that the successive peaks do exist. This test is repeated for various values of r ₀/Λ, which leads to the conclusion that there is really a periodic structure hidden behind the random surface.      

Attenuation of Λ(1520) Hyperons in near-threshold <Emphasis Type="Italic">pA</Emphasis> reactions

In the framework of the nuclear spectral function approach for incoherent primary proton-nucleon and secondary pion-nucleon production processes we study the inclusive Λ(1520)-hyperon production in the interaction of 2.83-GeV protons with nuclei. In particular, the A and momentum dependences of the absolute and relative Λ(1520)-hyperon yields are investigated within the different scenarios for their in-medium width. Our model calculations show that the pion-nucleon production channel contributes distinctly to the “low-momentum” Λ(1520) creation both in light and heavy nuclei in the chosen kinematics and, hence, has to be taken into consideration on close examination of the dependences of the Λ(1520)-hyperon yields on the target mass number with the aim to get information on their width in the medium. They also demonstrate that both the A dependence of the relative Λ(1520)-hyperon production cross section and momentum dependence of the absolute Λ(1520)-hyperon yield at incident energy of interest are appreciably sensitive to the Λ(1520) in-medium width, which means that these observables may be an important tool to determine the above width.     

Delayed clusters accompanying nonmesonic weak decay of the Λ-hypernuclei: a clue to nonleptonic processes

The nonmesonic decay of Λ-hypernuclei provides access to the nonleptonic weak decay process ΛN → NN, which is achievable only through the observation of hypernuclear ground-state decays. We continue the discussion of some specific cases which make it possible to detect a few exclusive transitions, namely, the stripping of nucleon from the ground state results in a resonance state decaying via emission of two clusters. Delayed clusters accompanying weak decay of light hypernuclei give a unique information on spin dependence of the weak decay matrix elements.     

Optical pumping in a L-system by parametric luminescence light

We examine the optical pumping effect in an ensemble of three-level atoms with a Λ configuration of the energy sublevels excited by parametric luminescence light in the squeezed state. We derive quantum kinetic equations that describe the evolution of the density matrix of atoms irradiated by low-intensity squeezed light with a finite-width spectrum. In particular, we show that because of the quantum statistical properties of the squeezed light there can be a redistribution of atoms among the lower energy sublevels, despite the equality of the intensities of the spectral components of the light that resonantly excites optical transitions in the Λ-system. The relation of the optical pumping effect to the correlation and spatial-temporal spectral properties of squeezed light is discussed in detail. Finally, we show that the effects are closely linked to the finiteness of the width of the squeezed-light spectrum. Zh. éksp. Teor. Fiz. 112, 137–162 (July 1997)     

Λ and the Heisenberg Principle

A time dependent “cosmological constant” Λ(t) is conjectured, in terms of the Gaussian curvature of the causal horizon. It is nonvanishing even in Minkowski space because of the lack of informations beyond the light cone. Using the Heisenberg Principle, the corresponding energy of the quantum fluctuations localized on the past or future null horizons is proportional to Λ^1/2. We compute Λ(t) for the (Lorenzian version) of the (conformally flat) Hawking wormhole geometry (written in static spherical Rindler coordinates) and for the de Sitter spacetime. A possible explanation of the Hawking temperature is proposed, in terms of a constant Λ.     

A semi-empirical formula for the energy spacings in Λ-hypernuclear excitation spectra

A semi-empirical formula is presented which gives a semi-quantitative account of the excitation energies in Λ-hypernuclear excitation spectra. Many elaborate studies made were numerical, but our studies yield an analytical expression. Different three-dimensional harmonic oscillators for the Λ- and the neutron-hole reproduce the observed energy spacings fairly well. However, it would be misleading that the oscillators give the wave functions of the corresponding states also. In the light of harmonic excitations, we briefly discuss some phenomenological and microscopic Λ-hypernuclear calculations.     

Study of ΛΛ dynamics and ground state structure of low and medium mass double Λ hypernuclei

We critically review the ΛΛ dynamics by examining Λ - Λ and Λ-nucleon phenomenological potentials in the study of the bound state properties of double-Λ hypernuclei _ΛΛ ⁶ He, _ΛΛ ¹⁰ Be, _ΛΛ ¹⁴ C, _ΛΛ ¹⁸ O, _ΛΛ ²² Ne, _ΛΛ ²⁶ Mg, _ΛΛ ³⁰ Si, _ΛΛ ³⁴ S, _ΛΛ ³⁸ Ar, _ΛΛ ⁴² Ca, _ΛΛ ⁴⁶ Ti, _ΛΛ ⁵⁰ Cr, _ΛΛ ⁵⁴ Fe, _ΛΛ ⁵⁸ Ni, _ΛΛ ⁶² Zn, _ΛΛ ⁶⁶ Ge, _ΛΛ ⁷⁰ Se, _ΛΛ ⁷⁴ Kr, _ΛΛ ⁷⁸ Sr, _ΛΛ ⁸² Zr, _ΛΛ ⁸⁶ Mo, _ΛΛ ⁹⁰ Ru, _ΛΛ ⁹⁴ Pd, _ΛΛ ⁹⁸ Cd, _ΛΛ ¹⁰² Sn in the frame work of (core+Λ+Λ) three body model. An effective ΛN potential is obtained by folding the phenomenological ΛN potential into the density distribution of the core nuclei. The former two cases (i.e. _ΛΛ ⁶ He and _ΛΛ ¹⁰ Be) are revisited to justify the correctness of the present potential model. Assuming the same potential model we predicted some of the structural properties of heavier doubly Λ-hypernuclei. The hyperspherical harmonics expansion method, which is an essentially exact method has been employed for the three body system. A convergence in binding energy up to 0.15% for K _max=20 has been achieved. In our calculation we have made no approximation in restricting the allowed l-values of the interacting pairs.     

A-dependence of the γ- and p-induced production of the Λ(1520) from nuclei

Using results of a recent calculation of the Λ(1520) in the nuclear medium, which show that the medium width is about five times the free width, we study the A-dependence of the Λ(1520) production cross-section in the reactions γA → K⁺Λ(1520)A^′ and pA → pK⁺Λ(1520)A^′. We find a sizable A-dependence in the ratio of the nuclear cross-sections for heavy nuclei with respect to a light one due to the large value of the Λ(1520) width in the medium, showing that devoted experiments, easily within reach in present facilities, can provide good information on that magnitude by measuring the cross-sections studied here.     

Structure of neutron-rich Λ hypernuclei

Properties of light neutron-rich Λ hypernuclei (¹⁶ _ΛC, ¹² _ΛBe, and ¹¹ _ΛLi) are calculated within the Skyrme-Hartree-Fock approach. Interplay between hypernuclear interaction features and properties of these hypernuclei is studied. Response of weakly bound neutron states to hyperon addition depends generally on core distortion by hyperon, and it is essentially different for the different states. This response is especially sensitive to details of the ΛN interaction for 1p _1/2 states. Implications of the nuclear spin-orbit potential and nuclear incompressibility in the neutron-rich system properties are inferred. Dependence of the Λ binding energies in hypernuclei on Z at fixed A is discussed. Received: 16 December 1998     

Measurement of K0S, Λ and Λ? production at HERA

The production of the neutral strange hadrons K⁰ _S, Λ and Λ̄ has been measured in ep collisions at HERA using the ZEUS detector. Cross sections, baryon-to-meson ratios, relative yields of strange and charged light hadrons, Λ (Λ̄) asymmetry and polarization have been measured in three kinematic regions: Q² > 25 GeV²; 5 < Q² < 25 GeV²; and in photoproduction (Q²≃0). In photoproduction the presence of two hadronic jets, each with at least 5 GeV transverse energy, was required. The measurements agree in general with Monte Carlo models and are consistent with measurements made at e⁺e^- colliders, except for an enhancement of baryon relative to meson production in photoproduction.     

ΛΛ-Ξ N coupling effects in light hypernuclei

The significance of ΛΛ-Ξ N coupling in double-Λ hypernuclei has been studied. The Pauli suppression effect due to this coupling in ⁶ _ΛΛ He has been found to be 0.43MeV for the coupling strength of the NSC97e potential. This indicates that the free-space ΛΛ interaction is stronger by an about 5^° phase shift than that deduced from the empirical data of ⁶ _ΛΛ He without including the Pauli suppression effect. In ⁵ _ΛΛ He and ⁵ _ΛΛ H, an attractive term arising from the ΛΛ-Ξ N conversion is enhanced by the formation of an alpha-particle in the intermediate Ξ states. According to this enhancement, we have found that the ΛΛ binding energy ( ΔB _ΛΛ) of ⁵ _ΛΛ He is about 0.27MeV larger than that of ⁶ _ΛΛ He for the NSC97e coupling strength. This finding deviates from the general picture that the heavier is the core nucleus, the larger is ΔB _ΛΛ.-1 Received: 17 July 2002 / Accepted: 27 September 2002 / Published online: 17 January 2003 RID="a" ID="a"e-mail: akaishi@post.ket.jp Communicated by A. Molinari     

Studying of hypernuclei with nuclotron beams

The hypernuclear program at Dubna was started in 1988 with investigation of the light hypernuclei production and decay [1]. Nowadays, we are planning to measure lifetime and production cross section of _Λ⁶He and _Λ⁶H hypernuclei.     

Longitudinal polarisation of Λ and Λ̄ hyperons in lepton–nucleon deep-inelastic scattering

We consider models for the spin transfers to Λ and Λ̄ hyperons produced in lepton–nucleon deep-inelastic scattering. We make predictions for longitudinal Λ and Λ̄ spin transfers for the COMPASS experiment and for HERA, and for the spin transfer to Λ hyperons produced at JLAB. We demonstrate that accurate measurements of the spin transfers to Λ and Λ̄ hyperons with COMPASS kinematics have the potential to probe the intrinsic strangeness in the nucleon. We show that a measurement of Λ̄ polarisation could provide a clean probe of the spin transfer from s̄ quarks and provides a new possibility to measure the antistrange quark distribution function. COMPASS data in a domain of x that has not been studied previously will provide valuable extra information to fix models for the nucleon spin structure. The spin transfer to Λ̄ hyperons, which could be measured by the COMPASS experiment, would provide a new tool to distinguish between the SU(6) and Burkardt–Jaffe (BJ) models for baryon spin structure. In the case of the HERA electron–proton collider experiments with longitudinally-polarised electrons, the separation between the target and current fragmentation mechanisms is more clear. It provides a complementary probe of the strange quark distribution and helps distinguish between the SU(6) and BJ models for the Λ and Λ̄ spin structure. Finally, we show that the spin transfer to Λ hyperons measured in a JLAB experiment would be dominated by the spin transfer of the intrinsic polarised-strangeness in the remnant nucleon, providing an independent way to check our model predictions. PACS 13.60.Rj; 13.87.Fh; 13.88.+e; 14.40.Ev; 14.20.Jn     

Autler—Townes effect in hyperfine structure of alkali-atom D 1 line

The Autler—Townes effect is considered for the case where a strong control field acts in the frequency profile of a hyperfine transition taking into account the hyperfine interaction. An exact expression is derived for the susceptibility of the medium with respect to a probe field that acts in the frequency profile of a coupled transition of the alkaliatom D ₁ line. It is shown that the hyperfine interaction in the excited state may substantially modify the susceptibility of the medium. In particular, it is shown that, when the control field is tuned to wings of atomic transitions, the structure of the Autler—Townes resonances appears to be noticeably differing from what is predicted by the Λ-scheme approximation. It is found that tuning of the control field frequency to between hyperfine components of the excited state enhances the resonant structure in this region. The results are discussed in terms of the quantum memory protocols based on the effects of Raman scattering and electromagnetically induced transparency.     

The search for and study of the strange multibaryon states in systems with Λ-hyperon and Ks0 -meson in pA collision at momentum of 10 GeV/c

Exotic strange multibaryon states have been observed in the effective mass spectra of: Λπ^±, Λπ⁺π⁻, Λp, Λpp, Λπp, ΛΛ and ΛK _s ⁰, K _s ⁰ p, K _s ⁰π^± subsystems. The measured Λ/π⁺ ratio for average multiplicities from the pC reaction is equal to (5.3 ± 0.8) × 10⁻², and it is approximately two times larger than the Λ/π⁺ ratio simulated by the FRITIOF model and than that of experimental pp reactions at the same energy. The observed wellknown resonances Σ*⁺ (1385) and K*^± (892) from PDG are good tests of this method. The mean value of the mass for the Σ*⁻(1385) resonance is shifted to 1370 MeV/c ² and the width is two times larger than the same value from PDG. Such kind of behavior for the width and invariant mass of Σ*⁻ (1385) resonance is interpreted as an extensive contribution from stopped Ξ⁻ → Λπ⁻ and medium effect. There is enhancement of the production contribution for all observed hyperons. A few events were registered by hypothesis of light H ⁰ and heavy H ^{0, +} dihyperons. Dihyperons were observed by weak decay channels: (Σ⁻ p), (Λpπ⁻), (Λpπ⁰), and (K ⁻ pp). The text was submitted by the author in English.