X-ray studies of the smectic B phase of the 4-bromobenzylidene-4′-alkoxyanilines

The results of X-ray studies of the nine members (4?÷?12) of the 4-bromobenzylidene-4′-alkyloxyaniline homologous series (nBBAA) in smectic B (SmB) and smectic A (SmA) phases are presented. Interestingly, no SmC phase was identified. The thickness of smectic layers in the SmA and SmB phases was estimated showing unexpectedly that in SmA it is bigger than in the SmB. For the SmB phase, orthorhombic unit cell parameters were determined as a function of temperature. The obtained data are discussed in relation to rotational dynamics.     

On the large order behavior of Φ 4 4

We continue the rigorous study of the large order behavior of the perturbation series for the ⁴ model in 4 dimensions started in [1]. In this paper we prove a result announced in [1]. We show that the exact radius of convergence of the Borel transform of the renormalized perturbation series for ₄ ⁴ is greater than or equal to the expected value given by the position of the first renormalon [2]. This result holds for any vector (²)² model withN components, and makes use of the Lipatov bound of [1]. This result is based on a partial resummation of counterterms similar to the one of [3], but in a phase-space analysis of the renormalized series.     

GEANT4 in the AliRoot Framework

The development of the GEANT4 application for ALICE simulation within the aliRoot framework is described.The G3toG4 approach adopted by ALICE collaboration is explained.The overview of the design,present implementation and functionality is presented and the remaining problems are discussed.     

Local existence of the Borel transform in Euclidean φ 4 4

We bound rigorously the large order behaviour of ₄ ⁴ euclidean perturbative quantum field theory, as the simplest example of renormalizable, but non-super-renormalizable theory. The needed methods are developed to take into account the structure of renormalization, which plays a crucial role in the estimates. As a main thorem, it is shown that the Schwinger functions at ordern are bounded byK ⁿ n!, which implies a finite radius of convergence for the Borel transform of the perturbation series.     

Gell-Mann-Low function in the ϕ4 theory

An algorithm is proposed for the determination of the asymptotics of a sum of a perturbation series from the given values of its coefficients in the strong-coupling limit. When applied to the ?⁴ theory, the algorithm yields the β(g)∝g ^α behavior with α≈1 at large g for the Gell-Mann-Low function.     

Anisotropy Spectra of the Solvent-Sensitive Fluorophore 4-Dimethylamino-4′-Cyanostilbene in the Presence of Light Quenching

We examined the emission wavelength-dependent anisotropies of the solvent-sensitive fluorophore 4-dimethylamino-4-cyanostilbene (DCS) under conditions of light quenching by polarized time-delayed quenching pulses. Illumination on the long-wavelength side of the emission spectrum with time-delayed light pulses resulted in a progressive decrease in the emission anisotropy as the observation wavelength increased toward the stimulating wavelength. The anisotropy changes of DCS were most wavelength dependent when spectral relaxation occurred during the excited-state lifetime. Light quenching of DCS in a low-viscosity solvent revealed no wavelength-dependent anisotropies. Control measurements using a solvent-insensitive fluorophore did not show any wavelength-dependent anisotropy with light quenching. The data for DCS can be explained by a model which allows wavelength-selective quenching of the long-wavelength emission formed by time-dependent spectral relaxation. These results indicate that polarized light quenching can be used to study systems which display multiple emissions and/or time-dependent spectral shifts.     

Construction of the Hierarchical φ4-Trajectory

We study the invariant unstable manifold of the trivial renormalization-group fixed point tangent to the ⁴-vertex in the hierarchical approximation. We parametrize it by a running ⁴-coupling with linear step -function. The manifold is studied as a fixed point of the renormalization group composed with a flow of the running coupling. We present a rigorous construction of it beyond perturbation theory by means of a contraction mapping. Starting from a perturbative approximant of order seven, we obtain a convergent representation in dimensions 2 < D < 28/9 with certain restrictions. The perturbative approximant is logarithmically divergent in D = 3 dimensions.     

Ground state of the 4α + Λ nucleus within the 4α+Λ cluster model

The s-wave bound state of the 4α+Λ system is investigated. The relevant solution to the Schrödinger equation is expanded in the basis formed by the eigenfunctions of Hamiltonian for the 4α subsystem. Differential equations for Yakubovsky components are employed to calculate basis functions. Phenomenological potentials for αα and αΛ interactions are used. In the 4α system, additional three-particle potentials for the interaction between α clusters are introduced in such a way as to reproduce the experimental data on the binding energies, the root-mean-square radii, and the charge form factors for the ¹²C and the ¹⁶O nucleus. The binding energy, the root-mean-square radius, and the hyperon distribution in the ground state of the _Λ ¹⁷ O nucleus are calculated. The results of the calculations are in good agreement with those obtained on the basis of the ¹⁶O+Λ two-particle model with the phenomenological Woods-Saxon potential.     

A high level computational study of the CH4/CF4 dimer: how does it compare with the CH4/CH4 and CF4/CF4 dimers?

The interaction within the methane–methane (CH₄/CH₄), perfluoromethane–perfluoromethane (CF₄/CF₄) methane–perfluoromethane dimers (CH₄/CF₄) was calculated using the Hartree–Fock (HF) method, multiple orders of Møller–Plesset perturbation theory [MP2, MP3, MP4(DQ), MP4(SDQ), MP4(SDTQ)], and coupled cluster theory [CCSD, CCSD(T)], as well as the PW91, B97D, and M06-2X density functional theory (DFT) functionals. The basis sets of Dunning and coworkers (aug-cc-pVxZ, x?=?D, T, Q), Krishnan and coworkers [6-311++G(d,p), 6-311++G(2d,2p)], and Tsuzuki and coworkers [aug(df, pd)-6-311G(d,p)] were used. Basis set superposition error (BSSE) was corrected via the counterpoise method in all cases. Interaction energies obtained with the MP2 method do not fit with the experimental finding that the methane–perfluoromethane system phase separates at 94.5?K. It was not until the CCSD(T) method was considered that the interaction energy of the methane–perfluoromethane dimer (?0.69?kcal?mol^?1) was found to be intermediate between the methane (?0.51?kcal?mol^?1) and perfluoromethane (?0.78?kcal?mol^?1) dimers. This suggests that a perfluoromethane molecule interacts preferentially with another perfluoromethane (by about 0.09?kcal?mol^?1) than with a methane molecule. At temperatures much lower than the CH₄/CF₄ critical solution temperature of 94.5?K, this energy difference becomes significant and leads perfluoromethane molecules to associate with themselves, forming a phase separation. The DFT functionals yielded erratic results for the three dimers. Further development of DFT is needed in order to model dispersion interactions in hydrocarbon/perfluorocarbon systems.     

Local existence of the Borel transform in euclidean massless Φ 4 4

We extend the methods of [1] to prove large order estimates on the renormalized Feynman amplitudes of massless ₄ ⁴ euclidean field theory, at non-exceptional momenta. The Borel transform of the perturbative series is analytic in a disk centered at the origin of the complex plane. This result is a step towards the rigorous investigation of the infra-red singularities in the Borel plane, for theories containing massless particles, like the gauge theories.     

Analyticity of scattering for the ϕ4 theory

We consider scattering for the equation (+m ²)+³=0 on four-dimensional Minkowski space. Form>0, one-to-one and onto wave operatorsW _± :HH are known to exist for all 0, whereH denotes the Hilbert space of finite-energy Cauchy data. We prove that the maps (,u)W _± (u) and (,u)(W _± )^–1 (u) are continuous from [0, )×H toH, and extend to real-analytic functions from an open neighborhood of {0}×H×{0}×H to the Hilbert spaceH _–1 of Cauchy data with Poincaré-invariant norm. Form=0, wave operatorsW _± are known to exist as diffeomorphisms ofH for all 0, where hereH denotes the Hilbert space of finite Einstein energy Cauchy data. In this case we prove that the maps (,u)(W _± ) (u) and (,u)(W _± )^–1 (u) extend to real-analytic functions from a neighborhood of [0, )×H×H toH.     

Lattice (Φ 4)4 effective potential giving spontaneous symmetry breaking and the role of the Higgs mass

We present a critical reappraisal of the available results on the broken phase ofλ(Φ ⁴)₄ theory, as obtained from rigorous formal analyses and from lattice calculations. All the existing evidence is compatible with Spontaneous Symmetry Breaking but dictates a trivially free shifted field that becomes controlled by a quadratic hamiltonian in the continuum limit. As recently pointed out, this implies that the simple one-loop effective potential should become effectively exact. Moreover, the usual naive assumption that the Higgs mass-squaredm _h ² is proportional to its “renormalized” self-couplingλ _R is not valid outside perturbation theory: the appropriate continuum limit hasm _h finite and vanishingλ _R . A Monte Carlo lattice computation of theλ(Φ ⁴)₄ effective potential, both in the single-component and in theO(2)-symmetric cases, is shown to agree very well with the one-loop prediction. Moreover, its perturbative leading-log improvement (based on the concept ofλ _R ) fails to reproduce the Monte Carlo data. These results, while supporting in a new fashion the peculiar “triviality” of theλ(Φ ⁴)₄ theory, also imply that, outside perturbation theory, the magnitude of the Higgs mass does not give a measure of the observable interactions in the scalar sector of the standard model.     

Semileptonic decays of the hypernucleus4HΛ

Two-channel type semileptonic decays of the hypernucleus⁴H are considered:⁴H_A ³H+p+^–+ and⁴H³He+n+^–+ . The particle energy spectra are computed taking into account the presence of strong interaction in the final state and the Pauli principle both in the direct and in the charge-exchange decay channels.The importance of the role played by interactions in forming the spectra of particles created in decays, is noted. Characteristic features of energy spectra and angular correlations of particles in the charge-exchange decay channel are discussed. The importance of such effects is noted for the dynamics of multichannel mesonless hypernuclear decays with similar energy release values.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 42–45, July, 1990.     

Challenge to the suppression of tumor growth by the β4-galactosyltransferase genes

It has been well established that structural changes in glycans attached to proteins and lipids are associated with malignant transformation of cells. We focused on galactose residues among the sugars since they are involved in the galectin-mediated biology, and many carbohydrate antigens are frequently expressed on this sugar. We found changes in the expression of the β4-galactosyltransferase (β4GalT) 2 and 5 genes in cancer cells: decreased expression of the β4GalT2 gene and increased expression of the β4GalT5 gene. The growth of mouse melanoma cells showing enhanced expression of the β4GalT2 gene or reduced expression of the β4GalT5 gene is inhibited remarkably in syngeneic mice. Tumor growth inhibition is probably caused by the induction of apoptosis, inhibition of angiogenesis, and/or reduced MAPK signals. Direct transduction of human β4GalT2 cDNA together with the adenovirus vector into human hepatocellular carcinoma cells grown in SCID mice results in marked growth retardation of the tumors. β4GalT gene-transfer appears to be a potential tool for cancer therapy.     

On the consistent solution of the gap-equation for spontaneously brokenλΦ 4-theory

We present a self-consistent solution of the finite temperature gap-equation for ⁴ theory beyond the Hartree-Fock approximation using a composite operator effective action. We find that in a spontaneously broken theory not only the so-called daisy and superdaisy graphs contribute to the resummed mass, but also resummed non-local diagrams are of the same order.herby@lapphpl.in2p3.fr     

What is the physics behind the 3He–4He anomaly?

We show that coalescence of nucleons emitted prior to thermalization in highly excited nuclei can explain the anomaly of kinetic energies of helium clusters. A new coalescence algorithm has been included in the statistical approach to nuclear reactions formerly used to describe intermediate mass fragment production. Received: 24 September 1999 / Revised version: 22 November 1999     

Design studies on the 4π γ-ray calorimeter for the ETF experiment at HIRFL-CSR

A high detection efficiency calorimeter which is used to detect γ-rays with energies from 1 MeV up to 10 MeV as well as light charged particles has been proposed.Design of the geometry,results of the crystal tests and Monte Carlo simulations are presented in this paper.The simulation results confirm that the calorimeter can obtain high detection efficiency and good energy resolution with the current designed geometry.And the calorimeter is competent for the future External Target Facility(ETF)experiments.     

Cascade corrected lifetimes of the 4p4DJ0 excited states in Ar II using the beam—foil technique

Transitions from the 4p⁴D_J⁰ levels in Ar II have been studied by using the beam—foil method. Using the ANDC method for cascade corrections we have determined the lifetimes of the 4p⁴D_{7/2, 5/2, 3/2, 1/2}⁰ levels. The results are compared with experimental and theoretical lifetimes.