N=2 affine superalgebras and Hamiltonian reduction inN=2 superspace

We constructN=2 affine current algebras for the superalgebrassl(n/n-1)⁽¹⁾ in terms ofN=2 supercurrents subjected to nonlinear constraints and discuss the general procedure of the hamiltonian reduction inN=2 superspace at the classical level. We consider in detail the simplest case ofN=2sl(2/1)⁽¹⁾ and show howN=2 superconformal algebra inN=2 superspace follows via the hamiltonian reduction. Applying the hamiltonian reduction to the case ofN=2sl(3/2)⁽¹⁾, we find two new extendedN=2 superconformal algebras in a manifestly supersymmetricN=2 superfield form. Decoupling of four component currents of dimension 1/2 in them yields, respectively,u(2/1) andu(3) Knizhnik-Bershadsky superconformal algebras. We also discuss how theN=2 superfield formulations ofN=2W ₃ andN=2W ₃ ⁽²⁾ superconformal algebras come out in this framework, as well as some unusual extendedN=2 superconformal algebras containing constrainedN=2 stress tensor and/or spin 0 supercurrents.     

Anomalous generation of Chern-Simons terms in D=3, N=2 supersymmetric gauge theories

Parity-invariant three-dimensional gauge theories with N=2 extended supersymmetry are studied by the heat kernel method. The parity-anomalous part of the one-loop effective action is exactly found. It is expressed in terms of the N=2 supersymmetric Chern-Simons term and is identified as a N=2 superspace Atiyah-Patodi-Singer eta-invariant.     

Mass Measurements of Exotic Nuclei around N=Z=40 with CSS2

Mass measurements of the N=Z nuclei ⁸⁰Zr, ⁷⁶Sr, ⁶⁸Se were performed for the first time and a new measurement was obtained for ⁸⁰Y, using the second cyclotron CSS2 of GANIL as a high-resolution spectrometer. Ions around N=Z were produced by fusion-evaporation in the inverse ⁵⁸Ni (4.32MeVA) + ²⁴Mg and ¹²C reactions. New masses were measured by a time-of-flight method, with a precision of 2⋅10⁻⁶, by using well-known masses as references. Study of the double binding energy difference δV _np is then performed leading to a strong N=Z Wigner effect around N=Z=40. Knowledge of new masses in this region also plays a crucial role in the modelling of the astrophysical rp process. This revised version was published online in July 2006 with corrections to the Cover Date.     

The role of isospin on the N=Z line

The role played by isospin in nuclear structure phenomena encountered on the N=Z line is discussed. New results on Coulomb energy differences (CED) at high spin for odd-A nuclei in the f _7/2 shell are presented and interpreted in the framework of a simple Cranked Shell Model treatment involving an exact numerical diagonalisation. Results for the CED between the A=46 even-even mirror pairs are also discussed. The CED between the T=1 states in N=Z odd-odd nuclei and their isobaric analogues are suggested as a possible probe of np pairing on the N=Z line. First results from a numerical diagonalization of IBM-4 are cited.     

A Trinomial Analogue of Bailey's Lemma and N = 2 Superconformal Invariance

We propose and prove a trinomial version of the celebrated Bailey's lemma. As an application we obtain new fermionic representations for characters of some unitary as well as nonunitary models of N= 2 superconformal field theory (SCFT). We also establish interesting relations between N= 1 and N= 2 models of SCFT with central charges and . A number of new mock theta function identities are derived. Dedicated to Dora Bitman on her 70th birthday Received: 8 March 1997 / Accepted: 29 June 1997     

Neutron Drip Line for Nuclei in the Vicinity of the Neutron Magic Number N = 184

Ground-state properties of even-even nuclei were calculated over a broad region of mass numbers, including nuclei that contain a neutron excess in the vicinity of the neutron drip line. The calculation of the properties of such nuclei relied on the method of the relativistic and the nonrelativistic mean field and took into account the axial deformation of nuclei. Particular attention was given to nuclei beyond the theoretical neutron drip line, which form a peninsula of nuclei in the (N, Z) space at N = 184 that are stable against the emission of one or two neutrons.

     

U(N) monopoles on Kerr black holes

We describe U(N) monopoles (N>1) on Kerr black holes by the parameters of the moduli space of holomorphic vector U(N) bundles over S ² with the help of the Grothendieck splitting theorem. For N=2, 3 we estimate the corresponding monopole masses. Pis’ma Zh. éksp. Teor. Fiz. 67, No. 12, 1021–1026 (25 June 1998) Published in English in the original Russian journal. Edited by Steve Torstveit.     

N=2 structures on solvable Lie algebras: Thec=9 classification

Let be a finite-dimensional Lie algebra (not necessarily semisimple). It is known that if is self-dual (that is, if it possesses an invariant metric) then it admits anN=1 (affine) Sugawara construction. Under certain additional hypotheses, thisN=1 structure admits anN=2 extension. If this is the case, is said to possess anN=2 structure. It is also known that anN=2 structure on a self-dual Lie algebra is equivalent to a vector space decomposition , where are isotropic Lie subalgebras. In other words,N=2 structures on in one-to-one correspondence with Manin triples . In this paper we exploit this correspondence to obtain a classification of thec=9N=2 structures on solvable Lie algebras. In the process we also give some simple proofs for a variety of Lie algebras. In the process we also give some simple proofs for a variety of Lie algebraic results concerning self-dual Lie algebras admitting symplectic or Kähler structures.     

Bianchi V models in N=2, D=5 supergravity

We investigate Bianchi V cosmological models containing two interacting scalar fields. These models are derived from a dimensional reduction of theN=2,D=5 supergravity theory. Exact solutions are found.     

Analysis of the Line Profiles of CH3CN for theJ= 5 ← 4 andJ= 6 ← 5 Rotational Transitions

The pressure broadening, pressure shift coefficients, and absolute intensities have been obtained for theJ= 6 ← 5 and theJ= 5 ← 4 absorption lines of acetonitrile CH₃CN at 110 and 92 GHz, respectively. The absorption line shapes have been directly recorded modulating the radiation beam by an optical chopper. In addition to the self-effects, the foreign-broadening coefficients have also been measured for N₂, O₂, and Ar.     

Bianchi VI0 models in N=2, D=5 supergravity

We investigate Bianchi VI₀ cosmological models containing two interacting scalar fields. These models are derived from a dimensional reduction of theN=2,D=5 supergravity theory. Exact solutions are found and the existence of singularities for them is considered.     

Nuclei near the closed shells N = 20 and N = 28

The present work reviews the properties of the neutron-rich isotopes near the closed shells N = 20 and N = 28. The changes in nuclear structure appearing as one goes away from the β-stability line are discussed. The location of the neutron drip line and questions about the stability of nuclides with Z ≥ 8 are considered in connection with the weakening or even vanishing of the shell effects at the magic numbers 20 and 28, and the discovery of the new neutron magic numbers at N = 16 and N = 32. These properties are extremely interesting from the point of view of laser experiments as well as for all other experimental methods giving access to this region.     

Soliton Solutions of the N=2 Supersymmetric KP Equation

Abstract

The N=2 super-KP equation associated with nonstandard flows is bilinearized using the Hirota method and soliton solutions are obtained. The bilinearization has been done for component fields and its KdV limit is discussed by comparing the soliton solutions obtained by this procedure with those found from the N=1 superspace formalism. The equivalence of these two procedures in the KdV limit is observed.     

Shape Coexistence and the N=28 Shell Closure Far from Stability

A mass measurement experiment by a time of flight method with the SPEG spectrometer at GANIL has been performed to investigate the N=20 and N=28 shell closures far from stability. The masses of 31 neutron-rich nuclei in the range A=29–47 have been measured. The precision of 19 masses has been significantly improved and 12 masses were measured for the first time. The neutron-rich Cl, S and P isotopes are seen to exhibit a change in shell structure around N=28. Comparison with shell model and relativistic mean field calculations demonstrate that the observed effects arise from deformed prolate ground state configurations associated with shape coexistence. The evidence of an isomeric state in the ⁴³S and its interpretation by a shell model calculation confirm the analysis of the masses and constitutes the first evidence of the predicted shape coexistence around N=28. This revised version was published online in July 2006 with corrections to the Cover Date.     

On realizations of exterior calculus with d N = 0

We study realizations of the q-exterior calculus with exterior differential d satisfying d ^N = 0, N > 2 on the free associative algebra with one generator and on the generalized Clifford algebras. Analogs of the notions of connection and curvature are discussed in the case of the q-exterior calculus on the generalized Clifford algebra. We show that the q-exterior calculus on the free associative algebra with one generator is related to q-calculus on the braided line.     

Evolution of the N = 20 and N = 28 shell closures in neutron-rich nuclei

The isospin dependence of shell closure phenomena is studied for light neutron-rich nuclei within a microscopic self-consistent approach using the Gogny force. Introducing configuration mixing, ³²Mg is found to be dynamically deformed, although the N = 20 spherical shell closure persists at the mean-field level for all N = 20 isotones. In contrast, the N = 28 spherical shell closure is found to disappear for N - Z≥ 10 whereas deformed shell closures are preserved and lead to shape coexistence in ⁴⁴ S. Configuration mixing shows that the ground state of this nucleus is triaxially deformed. The first 2⁺ excitation energy E_x = 1.46 MeV and the reduced transition probability B(E2;0⁺ _gs→ 2⁺ ₁)= 420 e ² fm ⁴ obtained with our approach are in good agreement with experimental data. Received: 26 July 2000 / Accepted: 30 August 2000     

Sasakian and Parabolic Higgs Bundles

Let M be a quasi-regular compact connected Sasakian manifold, and let N = M/S ¹ be the base projective variety. We establish an equivalence between the class of Sasakian G–Higgs bundles over M and the class of parabolic (or equivalently, ramified) G–Higgs bundles over the base N.     

On quasi-self-dual fields in N=4 supersymmetric Yang-Mills theory

A general representation for a quasi-self-dual gauge field which is a generalization of the 't Hooft ansatz is obtained in the Euclidean conformally invariant Yang-Mills theory with a sextuplet of real scalar fields-the boson sector of N=4 supersymmetric Yang-Mills theory. The existence of an O(4)-symmetric quasi-self-dual solution in the region g ²>0 is proved. An explicit example of the quasi-self-dual instanton in the region g ²<0 is constructed.