Exact SU(n) instantons with cylindrical symmetry

We construct SO(3) symmetric, irreducible instantons in an SU(n) gauge theory. The solutions are symmetric with respect to J = ?ir × ? + T, where T spans the maximal SO(3) subalgebra of SU(n). Our ansatz as well as the resulting self dual equations are closely related to those for monopoles.     

Quaternionic multi-S4 instantons in general covariant SU(2) Yang-Mills and HP(n) σ-models

It is shown that the quaternionic maps xⁿ = S⁴ → S⁴ are realized by the n-instanton solutions of two related types of general covariant field theories in four dimensions. They are, respectively, the Einstein-SU(2) Yang-Mills theory with a cosmological term and the new HP(m) σ-models     

Notes on integrable boundary interactions of open SU(4) alternating spin chains

Ref. [J. High Energy Phys. 1708, 001(2017)] showed that the planar flavored Ahanory-Bergman-Jafferis-Maldacena(ABJM)theory is integrable in the scalar sector at two-loop order using coordinate Bethe ansatz. A salient feature of this case is that the boundary reflection matrices are anti-diagonal with respect to the chosen basis. In this paper, we relax the coefficients of the boundary terms to be general constants to search for integrable systems among this class. We found that the only integrable boundary interaction at each end of the spin chain aside from the one in ref. [J. High Energy Phys. 1708, 001(2017)] is the one with vanishing boundary interactions leading to diagonal reflection matrices. We also construct non-supersymmetric planar flavored ABJM theory which leads to trivial boundary interactions at both ends of the open chain from the two-loop anomalous dimension matrix in the scalar sector.     

Resonant spin tunneling in small magnetic particles

A new macroscopic test of spin tunneling in single-domain magnetic particles is proposed. It is shown that quantization of spin, even in particles of a considerable size, may lead to a detectable zero-field maximum in the dependence of the rate of the magnetic relaxation on the magnetic field. This effect must be especially pronounced in antiferromagnetic particles. It is argued that recent observation by several groups of the non-monotonic field dependence of the blocking temperature in ferritin may, in fact, present the experimental evidence of this effect.     

An integrable SU(3) spin chain

An integrable SU(3) soin chain equation is constructed. An explicit form of the Lax-pair representation is given and it is shown to be gauge equivalent to a set of nonlinear Schrödinger- type equations for three complex variables.     

The 27-plet baryons with spin 3/2 under SU(3) symmetry

We investigate the spin-3/2 baryons in the 27-plet based on flavor SU(3) symmetry. For J ^p = 3/2⁺, we find all the candidates for non-exotic members. For J ^p = 3/2^-, we predict a new non-exotic member Λ(1780). Fitting the mass spectrum and calculating the widths of the members show an approximate symmetry of the 27-plet of SU(3). We find that the exotic members have relatively large widths and the Ξ(1950) has spin and parity J ^p = 3/2^-. The possibility of assigning the non-exotic candidates to an octet is also analyzed.     

Exact SU(2) symmetry and persistent spin helix in a spin-orbit coupled system

Spin-orbit coupled systems generally break the spin rotation symmetry. However, for a model with equal Rashba and Dresselhauss coupling constants, and for the [110] Dresselhauss model, a new type of SU(2) spin rotation symmetry is discovered. This symmetry is robust against spin-independent disorder and interactions and is generated by operators whose wave vector depends on the coupling strength. It renders the spin lifetime infinite at this wave vector, giving rise to a persistent spin helix. We obtain the spin fluctuation dynamics at, and away from, the symmetry point and suggest experiments to observe the persistent spin helix.     

Numerical analysis of tunneling paths in constant field SU(2) lattice gauge theory

We present results of a computer analysis of euclidean solutions of the SU(2) lattice gauge theory Hamiltonian for constant fields. The accumulation of tunneling solutions in a certain region of phase space is investigated because it is expected to give a strong contribution to the path integral. Our analysis shows, that an infinite set of classical trajectories with finite action exists, and describes how they cluster.     

Voltage-controlled spin selection in a magnetic resonant tunneling diode

We have fabricated all II-VI semiconductor resonant tunneling diodes based on the (Zn,Mn,Be)Se material system, containing dilute magnetic material in the quantum well, and studied their current-voltage characteristics. When subjected to an external magnetic field the resulting spin splitting of the levels in the quantum well leads to a splitting of the transmission resonance into two separate peaks. This is interpreted as evidence of tunneling transport through spin polarized levels, and could be the first step towards a voltage controlled spin filter.     

A silicon bag model with SU(2) × SU(2) chiral dynamics

We describe a soliton bag model which incorporates explicitly SU(2) × SU(2) chiral dynamics, including the conservation of the polar vector current, the partial conservation of the axial vector current, and the SU(2) × SU(2) current algebra. This model appears to be renormalizable so that higher order effects may be treated systematically.     

N = 4 supergravity theory with local SU(2) × SU(2) invariance

N = 4 supergravity theory has been formulated in two different equivalent forms, which may be expected to become inequivalent when the internal symmetry is gauged. The extension of the first form to include local SO(4) internal symmetry is known. In this paper the extension of the second form to local SU(2) × SU(2) invariance is given, and is indeed inequivalent to the first form. The second form is in general parity non-conserving, while both forms have scalar field potentials that are unbounded from below.     

Correlation of tunneling spectra in Bi(2)Sr(2)CaCu(2)O(8+delta) with the resonance spin excitation

New break-junction tunneling data are reported in Bi(2)Sr(2)CaCu(2)O(8+delta) over a wide range of hole concentration from underdoped (T(c) = 74 K) to optimal doped (T(c) = 95 K) to overdoped (T(c) = 48 K). The conductances exhibit sharp dips at a voltage, Omega/e, measured with respect to the superconducting gap. Clear trends are found such that the dip strength is maximum at optimal doping and that Omega scales as 4.9kT(c) over the entire doping range. These features link the dip to the resonance spin excitation and suggest quasiparticle interactions with this mode are important for superconductivity.     

Emergent SU(N) symmetry in disordered SO(N) spin chains

The European Physical Journal B - We report the first observation of the low-frequency Raman spectra of 2-propanol from ambient to supercritical condition. Phenomenological analysis is applied to...     

Transition between SU(4) and SU(2) Kondo effect

Motivated by experiments in nanoscopic systems, we study a generalized Anderson, which consist of two spin degenerate doublets hybridized to a singlet by the promotion of an electron to two conduction bands, as a function of the energy separation δ$\delta$ between both doublets. For δ=0$\delta =0$ or very large, the model is equivalent to a one-level SU(N$N$) Anderson model, with N=4$N=4$ and 2 respectively. We study the evolution of the spectral density for both doublets (ρ_1σ(ω)${\rho }_{1\sigma }(\omega )$ and ρ_2σ(ω)${\rho }_{2\sigma }(\omega )$) and their width in the Kondo limit as δ$\delta$ is varied, using the non-crossing approximation (NCA). As δ$\delta$ increases, the peak at the Fermi energy in the spectral density (Kondo peak) splits and the density of the doublet of higher energy ρ_2σ(ω)${\rho }_{2\sigma }(\omega )$ shifts above the Ferrmi energy. The Kondo temperature T_K (determined by the half-width at half maximum of the Kondo peak in density of the doublet of lower energy ρ_1σ(ω)${\rho }_{1\sigma }(\omega )$) decreases dramatically. The variation of T_K with δ$\delta$ is reproduced by a simple variational calculation.     

Asymptotically free SU(2) × SU(2) × SU(4) model of unified interaction

An asymptotically free SU(2) × SU(2) × SU(4) model of unified interaction is constructed. The gauge coupling constants are taken equal (in the order of magnitude) to the electromagnetic one. The strong interaction and the quark confinement is provided for by a gluonic mechanism. Some physical consequence of the model are briefly discussed.