On double polarization asymmetries in the elastic electron-proton scattering

Double polarization asymmetry D_p^(M) for the process of elastic electroweak scattering of the longitudinally polarized electrons by polarized proton target is considered with account of anapole G_1p and electric dipole moment (EDM) G_2p proton form factors. This asymmetry is only due to T-parity violating form factor G_2p, but does not directly depend on it, and having a significant value, allows to confirm the existence of the EDM of the proton.     

Constraints on nonsinglet polarized parton densities from the infrared-renormalon model

Using the infrared-renormalon approach, we obtain the constraints on the next-to-leading order nonsinglet polarized parton densities. The advocated feature follows from the consideration of the effect revealed in the rocess of the next-to-leading order fits to the data for the asymmetry of polarized lepton-nucleon scattering, which result in the approximate nullification of the 1/Q²-correction to A ₁ ^N (x, Q²).     

Single and double spin asymmetries in the elastic <Emphasis Type="Italic">e</Emphasis>-<Emphasis Type="Italic">d</Emphasis> scattering and their dependence on the deuteron wave function

Single and double spin asymmetries in the elastic electron-deuteron (e-d ) scattering were investigated. The tensor-deuteron asymmetries T_2i(i = 0, 1, 2) and the beam-vector-deuteron asymmetries T ^e _1i(i = 0, 1) were calculated and compared with the available experimental data. The sensitivity of the results for these spin asymmetries to the deuteron wave function has been investigated. The predicted asymmetries were found to be agree with one another and with experiment. It was found that, the double spin asymmetry T ^e ₁₀ is much smaller than the T ^e ₁₁-asymmetry. Therefore, in addition to the single tensor-deuteron asymmetry T₂₀, the doubly beam-vector-deuteron asymmetry T ^e ₁₁ can be used as an another tool for extracting the deuteron electromagnetic form factors.     

Level-crossing-Untersuchung der Hyperfeinstruktur des 3d 10 4p 2 P 3/2-Terms von Cu63 und Cu65

The level-crossing technic has been used to investigate the hyperfinestructur of the 3d ¹⁰ 4p ² P _3/2-term in Copper I by scattering the resonance line λ=3248 Å on an atomic beam of separated isotop Cu⁶³ respectively Cu⁶⁵ in an external magnetic field. From the level-crossing signals values for the magnetic dipol interaction constantsA and for the electric quadrupol interaction constantsB are deduced to beeA(Cu⁶³)=(194,72±0,15) Mc/secB(Cu⁶³)=?(28,8±0,6) Mc/secA(Cu⁶⁵)=(208,57±0,15) Mc/secB(Cu⁶⁵)=?(25,9±0,6) Mc/sec. With theA-value of the 3d ¹⁰ 4p²P_1/2-term from optical measurements the ratioA(² P _3/2)∶A(² P _1/2)≈0,4 is about twice greater than for an unperturbetalkali-like²P-term. From the width of the level-crossing signals a mean lifetime of the 3d¹⁰ 4p²P_3/2-term τ=(7,0±0,2) · 10^?9 sec is deduced.     

Spins und γ-Multipolordnungen beim Zerfall Fe59→Co59

In the decay of Fe⁵⁹ the following quantities have been measured:γ-ray intensities, conversion coefficients andβ-(circularly polarizedγ) correlations. The conversion coefficients were found to be: for the 1.10 MeVγ-transition, α_tot.=(1.36±0.10)·10^?4 and for the 1.29 MeVγ-transition, α_tot.=(1.07±0.08)·10^?4. The asymmetry parameterA of the correlationβ(0.27 MeV)?γ(1.29 MeV) were measured to beA= ?0.17±0.10, and forβ(0.46 MeV)?γ(1.10 MeV),A=?0.13±0.04. From these data and publishedγ?γ angular correlation measurements the following spins of Co⁵⁹ levels could be deduced: 1.10 MeV,I=5/2^?; 1.29 MeV,I=5/2^?; and 1.43 MeV,I=3/2^?. The two strongβ-ray groups are pure Gamow-Teller transitions (ΔI=1). The multipolarities of all fiveγ-rays are given.     

Violation of P- and T-symmetries in double polarized elastic electron-proton scattering

Analytical expressions are obtained for the differential cross section and right-left asymmetry A _RL ^γ,γZ of the process of elastic scattering of longitudinally polarized electrons from a polarized proton target with account of anapole and electric dipole moments, and the neutral weak electric, magnetic and axial form factors of a proton violating the C, P- and T/CP invariance. Contributions from the P and T odd spin correlations to asymmetry A _RL ^γ,γZ are studied as a function of the electron energy, scattering angles, and the proton form factors.     

Regge description of spin-spin asymmetry in photon diffractive dissociation

We explore the possibility to extract Δ(G(x) from a comparison of experimental data on the longitudinal spin-spin asymmetry A _LL in diffractive scattering of the heavy photon on the proton with calculations performed in perturbative QCD (pQCD). The data could be obtained at the HERA collider in scattering of polarized leptons off polarized protons. We have found a kinematic region where contributions to A _LL from soft processes are suppressed to guarantee an applicability of pQCD, hence the pQCD prediction can be reliably compared with data in this kinematic region.     

Präzisionsmessung der Hyperfeinstruktur des 52P3/2-Terms und des 62P3/2-Terms von Rb85 und Rb87

To study the modification of the value of the nuclear quadrupole moment obtained without Sternheimer correction from measurements in states with different principal quantum numbers, the hyperfine structure splitting of the 5² P _3/2 and the 6² P _3/2 excited states of Rb I has been investigated with the optical double resonance method. The experiments, in which isotopic enriched samples of Rb⁸⁵ and Rb⁸⁷ were used, have been carried out in the 5² P _3/2 state without a static magnetic field. In the 6² P _3/2 state, a static magnetic field was applied. For the 5² P _3/2 state, the hyperfine structure constants areA(Rb⁸⁵)=25.029(16) Mc/s,B(Rb⁸⁵)=26.032(70) Mc/s,A(Rb⁸⁷)=84.852(30) Mc/s,B(Rb⁸⁷)=12.611(70) Mc/s. The corresponding constants for the 6² P _3/2 state areA(Rb⁸⁵)=8.25(10) Mc/s,B(Rb⁸⁵)=8.16(20) Mc/s,A(Rb⁸⁷)=27.96(35) Mc/s,B(Rb⁸⁷)=3.95(10) Mc/s. The values of the nuclear quadrupole moments, derived from both finestructure states, can be brought into agreement when the Sternheimer core correction is applied. The Landé factor for the 6² P _3/2 state isg _j=1.334(1).     

On the structure of the von Neumann algebras generated by local functions of the free bose field

It is shown that the von Neumann algebra\(R_\mathfrak{B} \)(B) generated by any scalar local functionB(x) of the free fieldA ₀(x) is equal either to\(R_\mathfrak{B} \)(A ₀) or to\(R_\mathfrak{B} \)(:A ₀ ² :). The latter statement holds if the state space space\(\mathfrak{H}_B \) obtained from the vacuum state by repeated application ofB(x) is orthogonal to the one particle subspace. In the proof of these statements, space-time limiting techniques are used.     

Formfaktor des π-Mesons und Struktur der Nukleonen

Recent measurements of electron-proton scattering at Stanford have shown that the electric and magnetic form factors are not equal. Therefore, the isotopic vector parts of the form factorsG _e ^v andG _m ^v are recalculated with unsubtracted dispersion relations in the 2π-approximation. For the isotopic scalar parts we useG _e ^s (s)≈G _e ^v (s) andG _m ^s (s)≈ 0 which is known to be valid for moderate energy-momentum transfers. We obtain a simple closed expression for the electromagnetic form factor of the pionF _π in terms of the scattering lengtha ₁ and the effective ranger ₁ of the π-π-scattering in the stateL=T=1.a ₁ is roughly known from pion production by pions. With this value and a suitabler ₁,F _π has a resonance in the region of time-like energy-momentum transfer; and the pion rms-radius becomes\(\overline {v_\pi ^2 } = (0.82 \times 10^{ - 13} cm)^2 \). The calculated anomalous magnetic moment, the electric and the magnetic rms-radii of the proton are then within 10% of the experimental values, the electric charge within 30%. Moreover, the proton form factors are different from each other and up to an energy-momentum transfer of\(s = \frac{{ - q^2 }}{{m_\pi ^2 }} = 23\) within the experimental error of the new measurements. The deviations for higher values of the energy-momentum transfer may be explained in terms of the isotopic scalar parts of the form factors. In this case the electric form factor of the neutron will be different from zero in that region and the magnetic form factor of proton and neutron will no longer be equal. For comparison with other experiments we also calculate the π⁺?π^? cross section with neglect of other states thanL=T=1. Under this assumption the π?π cross section has a resonance for low energy-momentum transfer.     

Correlation between the properties of the deuteron and the low-energy triplet parameters of neutron-proton scattering

The correlation between the asymptotic normalization constant for the deuteron, A_S, and the neutron-proton scattering length for the triplet case, a_t, is investigated. It is found that 99.7% of the asymptotic constant A_S is determined by the scattering length a_t. It is shown that the linear correlation between the quantities A _S ^?2 and 1/a_t provides a good test of correctness of various models of nucleon-nucleon interaction. It is revealed that, for the normalization constant A_S and for the root-mean-square deuteron radius r_d, the results obtained with the experimental value recommended at present for the triplet scattering length a_t are exaggerated with respect to their experimental counterparts. By using the latest experimental data obtained for phase shifts by the group headed by Arndt, it proved to be possible to derive, for the low-energy parameters of scattering (a_t, r_t, P_t) and for the properties of the deuteron (A_S, r_d) results that comply well with experimental data.     

High-pressure behavior of the bond-bending mode of AIN

Lattice vibrations of the wurtzite-type AIN have been studied by Raman spectroscopy under high-pressure up to the phase transition to the rock salt structure at 20 GPa. Five fundamental bands E ₂ ² , A₁(TO), E₁(TO), A₁(LO), and E₁(LO) have a strong, positive pressure shift, whereas the shift of the low-frequency E ₂ ¹ band is weakly positive. We have found that the bond-bending mode has a positive mode Grüneisen parameter γ_i = 0.04, which is qualitatively consistent with the recently reported value γ_i = 0.12 [21]. Thus, we confirm that AIN remains stable with respect to the bond-bending mode, while in most tetrahedral semiconductors, bond-bending modes soften on compression. Experimental results are compared with the first-principle calculations.     

Charge radii in modern macroscopic-microscopic mass models: The role of dynamic quadrupole deformation

We calculate the charge radii of nuclei in the frame of the finite-range droplet model including axial and reflection asymmetry. In addition, in order to empirically include dynamic contributions into the radius calculations, we use the quadrupole deformation \( \beta_{{2}}^{}\) deduced from the experimental B(E2;0₁ ⁺ \( \rightarrow\) 2₁ ⁺) value as an input parameter. It is found that the calculated charge radii are in poor agreement with measured charge radii in the mass regions A < 110 and A > 210 . A slight systematic deviation is observed for the difference between model predictions and experiment for 110 < A < 210 . However calculated changes of charge radii along isotope chains are in better agreement with the experimental data when \( \beta_{{2}}^{}\) ’s from B(E2;0₁ ⁺ \( \rightarrow\) 2₁ ⁺) values are used instead of the model \( \beta_{{2}}^{}\) ’s.     

On the dependence of the single-spin asymmetry of charged pions on kinematical variables

The experimental single-spin asymmetry (A _N ) of charged pions produced in proton-proton and proton-nucleus collisions is analyzed phenomenologically as a function of kinematical variables. It is shown that the c.m. pion threshold energy (E ₀ ^c.m. ) above which |A _N | is positive depends on the reaction energy √s and on the particle-production angle θ ^c.m.. The dependence of the single-spin asymmetry on the kinematical variables in the region specified by the inequalities 0.7 < p _T < 2.7 GeV/c and E ^c.m. > E ₀ ^c.m. exhibits a scaling behavior. The dependence of A _N on √s proves to be significant at moderate and low energies. Formulas that make it possible to predict the behavior of A _N for charged pions over a broad region of kinematical variables are derived.     

Testing the Distance-Duality Relation from Hubble,Galaxy Clusters and Type Ia Supernovae Data with Model Independent Methods

In this paper, we perform cosmological-model-independent tests for the distance-duality (DD) relation η(z)=D _L(1+z)^?2/D _A by combining the angular diameter distance D _A(or comoving distances D _c ) with the luminosity distance D _L. The D _A are provided by two galaxy clusters samples compiled by De Filippis et al. (the elliptical β model), Bonamente et al. (the spherical β model), the D _c are obtained from Hubble parameter data and D _L are given from the Union2.1 supernovae (SNe) Ia compilation. We employ two methods, i.e., method A: binning the SNe Ia data within the range Δz=|z?z _SNe|<0.005, and method B: reconstructing the D _L(z) by smoothing the noise of Union2.1 data set over redshift with the Gaussian smoothing function, to obtain D _L associated with the redshits of the observed D _A or D _c. Four parameterizations for η(z), i.e., η(z)=1+η ₀ z, η(z)=1+η ₀ z/(1+z), η(z)=1+η ₀ z/(1+z)² and η(z)=1?η ₀ ln(1+z), are adopted for the DD relation. We find that DD relation is consistent with the present observational data, and the results we obtained are not sensitive to the method and parameterization.     

Effect of the orbital structure and symmetry of electronic states on nonradiative <Emphasis Type="Italic">S-T</Emphasis> intersystem crossing: Dibenzofuran

The nonradiative S-T intersystem crossing S ₁(ππ*) ? T ₁(ππ*) in dibenzofuran (DB(O)) molecules has been theoretically investigated within the model of vibronically induced spin-orbit (VISO) coupling of electronic states, where the vibronic perturbation takes into account all out-of-plane vibrational modes of a molecule. It is established that the S-T intersystem crossing S ₁(¹ A ₁) ? T ₁(³ B ₂) involves also the intermediate (T _m )T ₂(³ A ₁) and T ₃(³ B ₂) triplet states. The calculated rate constant K _ST = (4.5–4.7) × 10⁷s^?1 of the nonradiative transition is in agreement with the known experimental data. The manifestation of approximate (belonging to the D _2h group) symmetry of singlet and triplet molecular states in VISO couplings has been studied. An effect of the heavy (oxygen) atom of a DB(O) molecule on K _ST is established.     

Relaxation of a 2D MHD flow across a magnetic field (2D hydrodynamic flow) in a bounded region

The problem on magnetohydrodynamic (MHD) flow of a solitary vortex across a magnetic field in a volume confined by rigid walls is solved numerically for large Reynolds numbers (including magnetic Reynolds numbers) and small Alfven-Mach numbers M _A . In this case, the MHD problem is reduced to that of two-dimensional hydrodynamic turbulence. It is shown that sound is not generated by a turbulent medium for small values of M _A ; consequently, this kinetic energy dissipation channel is closed in this case. Calculations show that, in contrast to 3D turbulence, kinetic energy dissipation for 2D turbulence occurs, as expected, over time periods on the order of L²/v(L is the characteristic size of the system and v is the kinematic viscosity). In our calculations with numerical viscosity v～vΔx (Δx is the unit cell size), this corresponds to time values on the order of ～(L/Δx)(L/v). In the kinetic energy spectra for a turbulent flow in a bounded region in the inertial interval (lying between the energy-carrying and viscosity regions), the values of E(k) decrease with increasing wave numbers k at a higher rate than in proportion to k^?3. The volume distribution of vorticity becomes narrower with time (the characteristic values of curlv decrease) and is blurred; for large time periods, the distribution approximately retains its shape as well as asymmetry with respect to positive and negative values, which is associated with the asymmetry of the initial conditions.     

<Emphasis Type="Italic">nd</Emphasis> scattering at low energies in the two-body potential model

The S-wave phase shift δ(E) for the spin-doublet nd scattering at low energy E is calculated in the framework of the two-body approach. The effective-range-theory formula k cot δ = (1+k²/k ₀ ² )^?1(?1/α+C₂k²+C₄k⁴) is used to obtain approximate analytical results with different potentials. The corresponding coefficients C₂ and C₄ are obtained from our previous calculations of the asymptotic normalization parameter function C _t ² (aκ), where κ is the triton wave number and a is the doublet nd scattering length. The model reasonably describes δ(E), the results being quite sensitive to the choice of the effective nd potential.     

Spin-selective low temperature spectroscopy on single molecules with a triplet-triplet optical transition: Application to the NV defect center in diamond

The spin-selective photokinetics of a single matrix-isolated impurity molecule with a triplet-triplet optical transition, T ₀–T ₁, is considered and the manifestations of the photokinetics in the fluorescence excitation spectra and intensity autocorrelation functions g ⁽²⁾(τ) of the molecule undergoing narrow-band optical excitation is studied to resolve the fine structure of the transition. The rates of intersystem crossings (ISCs) T ₁→S→T ₀ to and from a nonradiating singlet state S of the molecule and the rate of population relaxation among the ground (T ₀) state sublevels can be obtained from the spectra and g ⁽²⁾(τ) using the analytical expressions obtained. New experiments on an individual NV defect center in nanocrystals of diamond, where, for the first time, the fine structure of its triplet-triplet ³ A-³ E zero-phonon optical transition (~637 nm) at 1.4 K was resolved, are interpreted. It is concluded that the rate of the ISC transition from the m _S =0 sublevel of the excited ³ E state to the singlet ¹ A state (~1 kHz) is much slower than the rates from the m _S =±1 substates, while the rates of ISC transitions to different m _S substates of the ground ³ A state are close to each other (~1 Hz). As a result, only the optical transition between m _S =0 sublevels in the ³ A-³ E manifold contributes strongly to the fluorescence. The experimentally observed double-exponential decay of the g ⁽²⁾(τ) function is explained by the two pathways available to the center for it to leave the S state: (i) the S→ T ₀(m _S )=0) transition and (ii) the S→T ⁰(m _S =±1) transitions followed by the slow spin-lattice relaxation T ₀(m _S =±1)→T ₀(m _S =0) (rate ~0.1 Hz). The work is important for studies where the NV center is used as a single photon source or for quantum information processing.