Resonance studies at STAR

Preliminary results from measurements of resonances (K ^*0(892), $\overline {K*^0 } (892)$ , Φ(1020), and ρ(770)) and weakly decaying particles (Λ(1116), $\bar \Lambda (1116)$ , and K _S ⁰ (498)) are presented. The measurements are performed at mid-rapidity by the STAR detector in $\sqrt {s_{NN} } = 130$ GeV Au?Au collisions at RHIC. The ratios K ^*0/h?, $\overline {K*^0 } /K$ , and $\bar \Lambda /\Lambda $ are compared to measurements at different energies and colliding systems. Estimates of thermal parameters, such as temperature and baryon chemical potential, are also presented.     

The Charmonium-Molecule Hybrid Structure of the X(3872)

In order to understand the structure of the X(3872) the effects of the ${{\rm c\overline{c}}}$ charmonium core state coupling to the ${D^0\overline{D}^{*0}}$ and D ⁺ D ^*? molecule states are studied. The obtained structure of the X(3872) is about 9 % of ${{\rm c}\overline{{\rm c}}}$ charmonium, 75 % of the isoscalar ${D\overline{D}}$ molecule and 16 % of the isovector ${D\overline{D}}$ molecule which explains observed properties of the X(3872) well.     

Synthesis and Spectroscopic Studies of 3-(3 N-Arylidenehydrazino-1,2,4-triazol-5-yl)-coumarins and Their Biological Activities

The electronic absorption spectra of 3-(3 N-arylidenehydrazino-1,2,4-triazol-5-yl) coumarin III are investigated in organic solvents of varying polarities and buffer solutions of different PH. The behaviour of the latter is utilized in calculating pka values of these compounds. The important bands in the IR spectra and the main ¹H NMR signals are assigned and discussed in relation to molecular structure. The antimicrobial activity of these compound has been investigated.     

The atomic structure of the 1/3\langle 2\overline 1 \overline 1 0\rangle superdislocation core and prismatic slip in Ti3Al

The structure of the core of a $1/6\langle 2\overline 1 \overline 1 0\rangle $ superpartial dislocation in the prism plane of the D0₁₉ superlattice is studied by computer simulation. Atomic interaction potentials for Ti₃Al are derived with the embedded atom method. The core of the superpartial dislocation is found to have three different configurations (of I′, I, and II types) in nonequivalent prism planes $\{ 0\overline 1 10\} $ . For screw and edge dislocations, the core is planar in type-I′ prism planes and nonplanar in prism planes of type I and II. Results of simulation are compared with experimental data for the superdislocation mobility in Ti₃Al.     

Strong decays ofΨ(4.03) andΨ(4.16) as radial excitations of charmonium

Considering the signals detected at 4.03 and 4.16 GeV as radial excitations of charmonium, we study their relative decay rates intoD \(\bar D\) ,D \(\bar D^* \) ,D ^* \(\bar D\) ,D ^* \(\bar D^* \) . We point out that one can understand these two peaks as ac \(\bar c\) 3S?2D wave state system with a large mixing angle in a Coulomb+linear interquark potential. We also examine the possibility that these two signals are respectively 3S and 4S wave excitations by studying a logarithmic charmonium potential model. We show that both these interpretations lead to drastically different predictions for the Ψ (4.16) decay rates (eitherD \(\bar D^* \) +D ^* \(\bar D\) orD \(\bar D\) mode is strongly suppressed) which would be very instructive to test experimentally.     

Umladung und Ionisation beim Durchgang von leichten und schweren Wasserstoffionen durch leichten und schweren Wasserstoff

Charge exchange and ionisation cross-sections were measured for the interaction of H⁺, H ₂ ⁺ , D⁺ and D ₂ ⁺ ions with H₂ and D₂ in the energy range 1.5–30 keV. In contrary to earlier measurements showing no isotope effect for a given ion velocity the results were as follows:

1. a)
   The charge exchange cross-sections depend on the proportion of the ion massm ₁ and the mass of the target moleculem ₂. The cross-sections increase with increasingm ₂/m ₁.     
   
   

Solid-state morphology and mechanical properties of Kevlar 29 fiber

Kevlar 29 is an aromatic polyamide fiber spun from the polymer poly(p-phenylene terephthalamide). It has a paracrystalline structure with a lattice distortion parameter g = 5.9% and an a? constant = 0.51. The equatorial x-ray “crystallinity” is 68%; the microparacrystal (mPC) sizes are D ₀₀₂ = 50 nm, D ₁₁₀ = 4.4 nm, and D ₂₀₀ = 3.6 nm. The mPCs are well oriented; the orientation parameter 2ψ₂₀₀> = 0.047. The small-angle x-ray diffraction pattern indicated that the fiber has nc chain folding. It has high tenacity (2.81 GNm^?2), close to the tenacity of steel; high Young's modulus (63.9 GNm^?2); small breaking strain (3.8%); and a very high melting point (600°C). Wide- and small-angle x-ray diffraction techniques, differential scanning calorimetry (DSC), and an Amsler tensile tester have been used to characterize the fiber and to assess the effect of annealing on its morphology and mechanical properties.     

Looking for new physics in leptonic and semileptonic decays of <Emphasis Type="Italic">B</Emphasis>-meson

We probe possible new physics (NP) effects beyond the standard model (SM) in the decays \({\overline B ^0} \to \pi \tau \overline \upsilon ,{\overline B ^0} \to \rho \tau \overline \upsilon ,and{\overline B ^0} \to \tau \overline \upsilon \), based on an effective Hamiltonian including non-SM operators. Experimental constraints on different NP scenarios are provided by recent measurements of the ratios \({{R\left( {{D^{\left( * \right)}}} \right) \equiv B\left( {{{\overline B }^0} \to {D^{\left( * \right)}}\tau \overline \upsilon } \right)} \mathord{\left/ {\vphantom {{R\left( {{D^{\left( * \right)}}} \right) \equiv B\left( {{{\overline B }^0} \to {D^{\left( * \right)}}\tau \overline \upsilon } \right)} {B\left( {{{\overline B }^0} \to {D^{\left( * \right)}}\mu \overline \upsilon } \right)}}} \right. \kern-\nulldelimiterspace} {B\left( {{{\overline B }^0} \to {D^{\left( * \right)}}\mu \overline \upsilon } \right)}}\), as well as the branching \(B\left( {{B^ - } \to \tau \overline \upsilon } \right)\). The corresponding hadronic form factors and leptonic decay constants are calculated in the covariant confined quark model developed by us.     

Three-loop relation of quark\overline {MS} and pole masses

We calculate, exactly, the next-to-leading correction to the relation between the \(\overline {MS} \) quark mass, \(\bar m\) , and the scheme-independent pole mass,M, and obtain $$\begin{gathered} \frac{M}{{\bar m(M)}} \approx 1 + \frac{4}{3}\frac{{\bar \alpha _s (M)}}{\pi } + \left[ {16.11 - 1.04\sum\limits_{i = 1}^{N_F - 1} {(1 - M_i /M)} } \right] \hfill \\ \cdot \left( {\frac{{\bar \alpha _s (M)}}{\pi }} \right)^2 + 0(\bar \alpha _s^3 (M)), \hfill \\ \end{gathered} $$ as an accurate approximation forN _F?1 light quarks of massesM _i <M. Combining this new result with known three-loop results for \(\overline {MS} \) coupling constant and mass renormalization, we relate the pole mass to the \(\overline {MS} \) mass, \(\bar m\) (μ), renormalized at arbitrary μ. The dominant next-to-leading correction comes from the finite part of on-shell two-loop mass renormalization, evaluated using integration by parts and checked by gauge invariance and infrared finiteness. Numerical results are given for charm and bottom \(\overline {MS} \) masses at μ=1 GeV. The next-to-leading corrections are comparable to the leading corrections.     

Allowable irreducible representations of the point groups with five-fold rotational axes

Allowable irreducible representations of the point groups with five-fold rotations – that represent the symmetry of the quasicrystals in two and three dimensions – are derived by employing the little group technique in conjunction with the solvability property. The point groups D $_{5h} ({\overline {10} {\text{{\emph m}}}2})$ and ${\text{{\emph I}}}_h (\frac{2}{\text{{\emph m}}}\overline 3 \,\overline 5)$ are taken to illustrate the method.     

Tin Mössbauer spectroscopy of tin-rich iridium-tin alloys

Ir₅Sn₇, Ir₃Sn₇ and newly obtained IrSn₄ /4/ exhibit complex Mössbauer spectra. The positions of the individual lines range from 0.82 to 3.0 mm/s and the average isomer shift \(\overline {IS} \) derived for each compound of Sn atomic percentage x follows the relationship: \(\overline {IS} = 0.60 + 0.0194 x\) . Rather large quadrupole splittings are obtained. The f factors are about 0.20 at 295 K and 0.37 at 78 K, from which Debye temperatures of 200 to 300 K have been calculated.     

Einfluß der Pion-Pion-Wechselwirkung auf Pion-Nukleon-Streuphasen

The isospin dependent part of theS-wave pion-nucleon amplitude is calculated according to the CGLN approach, but recoil and projection on the partial waves are treated exactly. Then the difference against the experimental data is approximately a constant up to 100 MeV and amounts to 1/3 of the total value. It is shown, that at low energies the main corrections of the CGLN equations are taken into account by a subtraction of theπ+π→?+\(\overline \Re \),J=I=1 amplitudesf _± ¹ (t) as proposed byMandelstam andFrazer. Calculations have been done forS, P andD pion-nucleon amplitudes. The main result is a prediction of theS-wave amplitude obtained without adjusting free parameters up to 100 MeV. The relations of this method to the equations derived byBowcock, Cottingham andLurié according to the Cini-Fubini approach are discussed.     

Electron-microscopic study of microcracks in single-crystal Ti<Subscript>3</Subscript>Al

Microcracks in a Ti₃ Al alloy subjected to indentation at room temperature were studied by transmission electron microscopy. The microcracks are shown to grow on \(\{ 0\overline 1 11\} \) pyramidal planes and in the slip bands of 2c + a superdislocations on \(\{ 20\overline 2 1\} \) and \(\{ 11\overline 2 1\} \) pyramidal planes. It is found that, due to the formation of a slip band in the basal plane at a microcrack tip, the propagating microcrack becomes steplike rather than straight. It is shown that a microcrack can nucleate at the line of intersection of \(\{ 11\overline 2 1\} \) pyramidal and \(\{ 0\overline 1 10\} \) prismatic planes.     

Electromagnetic and strange probes of dense nuclear matter at NICA/MPD: a feasibility study

The main task of the NICA/MPD physics program is a study of the properties of nuclear matter under extreme conditions achieved in collisions of heavy ions. These properties can reveal themselves through different probes, the most promising among those being the lepton-antilepton pairs and strange hadrons. In this paper the MPD performance for measuring the electron-positron pairs and strange particles (Λ, Ξ^– and Ω^– hyperons and their antiparticles \(\overline \Lambda \), \({\overline \Xi ^ + }\) and \({\overline \Omega ^ + }\) as well as hypernuclei ₃ ^Λ Λ) in central Au + Au collisions at NICA energies is presented.     

Cold flow of glassy polymers. II: Ductility,impact resistance,and unoccupied volume

A definition of maximum fractional unoccupied volume, f = 1.0 – (d_a/d_c), is presented for amorphous crystallizable polymers, f differs for various polymers at T_g, depending on the conformability of the polymer. It is large, at T, for sterically hindered or bulky polymers but low for flexible polymers. There is a reasonably good correlation between f and impact strength. In addition, one can explain the effect of “antiplasticizers.”     

A coupled-channel treatment of Cabibbo-angle favoured (D,D s + )→VP decays

We have performed a two-channel calculation of Cabibbo-angle favoured decays,D _s ⁺ →VP. We find a satisfactory fit toS _s ⁺ →φπ ⁺,ρ ⁰ π ⁺ andK ⁺ \(\bar K^{ * 0} \) data from ARGUS and E-691. We have also studied Cabbibo-angle favouredD→VP decays in a coupled channel formalism. We coupleD→K ^*π,K _? and \(\bar K^0 \phi \) channels inI=1/2 state, andK ^*π andK _? channels inI=3/2 state. We leave the two channels, \(\bar K^0 \omega \) and \(\bar K^{ * 0} \eta \) out of our unitarization scheme. Particular attention is paid to the role of the weak annihilation term in these decays.     

Antiproton low-energy collisions with Ps-atoms and true muonium atoms (μ + μ −)

Three-charge-particle collisions with participation of ultra-slow antiprotons ( \(\overline {\rm {p}}\) ) is the subject of this work. Specifically we compute the total cross sections and corresponding thermal rates of the following three-body reactions: \(\overline {\rm p}+(e^+e^-) \rightarrow \overline {\rm {H}} + e^-\) and \(\overline {\rm p}+(\mu ^+\mu ^-) \rightarrow \overline {\rm {H}}_{\mu } + \mu ^-\) , where \(e^-(\mu ^-)\) is an electron (muon) and \(e^+(\mu ^+)\) is a positron (antimuon) respectively, \(\overline {\rm {H}}=(\overline {\rm p}e^+)\) is an antihydrogen atom and \(\overline {\rm {H}}_{\mu }=(\overline {\rm p}\mu ^+)\) is a muonic antihydrogen atom, i.e. a bound state of \(\overline {\rm {p}}\) and μ ⁺. A set of two-coupled few-body Faddeev-Hahn-type (FH-type) equations is numerically solved in the framework of a modified close-coupling expansion approach.     

Formation of microcracks in an indented Ti<Subscript>3</Subscript>Al intermetallic compound

Microcracks in the Ti₃Al alloy indented at room temperature have been analyzed by electron microscopy. Analysis of the microstructure has revealed that microcracks propagate in the {0\(\overline 1 \)11} pyramidal planes and in the slip bands of the 2c + a superdislocations in the {20\(\overline 2 \)1} and {11\(\overline 2 \)1} pyramidal planes. It is found that the formation of a slip band in the basal plane at the microcrack tip leads to a change in the character of microcrack propagation from straight-line to steplike.     

Mössbauer study on Fe0.068Ni0.932Cl2 with competing spin anisotropies

Mössbauer measurements on Fe_0.068Ni_0.932Cl₂ were done at temperatures between 55K and 4.2K. We have found that below T_N-50K an observed spectrum is composed of two kinds of spectra and that the composition ratio changes gradually with temperature. The average angle of Fe²⁺ spins, \(\overline {\theta _{Fe} } \) , with the c-axis is smaller than \(\overline {\theta _c } \) by ?15° at each temperature below T_N, where \(\overline {\theta _c } \) is the average angle of total spins with the c-axis in this system obtained from the neutron scattering measurements. This is reasonably understood if we take into account that Fe²⁺ spins have the strong uniaxial anisotropy along the c-axis. We discuss the coexistence of the two kinds of spectra by considering the exchange energy of Fe²⁺ spins and the local magnetic anisotropy.     

The vector coupling α V((r) and the scales r 0, r 1 in the background perturbation theory

We study the universal static potential V _st(r) and the force, which are fully determined by two fundamental parameters: the string tension σ = 0.18 ± 0.02 GeV² and the QCD constants \(\Lambda _{\overline {MS} } (n_f )\) , taken from pQCD, while the infrared (IR) regulator M _B is taken from the background perturbation theory and expressed via the string tension. The vector couplings α _V(r) in the static potential and α _F(r) in the static force, as well as the characteristic scales, r ₁(n _f = 3) and r ₀(n _f = 3), are calculated and compared to lattice data. The result \(r_0 \Lambda _{\overline {MS} } (n_f = 3) = 0.77 \pm 0.03\) , which agrees with the lattice data, is obtained for M _B = (1.15 ± 0.02) GeV. However, better agreement with the bottomonium spectrum is reached for a smaller \(\Lambda _{\overline {MS} } (n_f = 3) = (325 \pm 15)\) MeV and the frozen value of α _V = 0.57 ± 0.02. The mass splittings \(\bar M(1D) - \bar M(1P)\) and \(\bar M(2P) - \bar M(1P)\) are shown to be sensitive to the IR regulator used. The masses M(1 ³ D ₃) = 10169(2) MeV andM(1 ³ D ₁) = 10155(3) MeV are predicted.