36 research outputs found
The variant of ADHMN construction associated with q-analysis
A q-deformation of the ADHMN caloron construction is considered, under which
the anti-selfdual (ASD) conditions of the gauge fields are preserved. It is
shown that the q-dependent Nahm data with certain constraints are crucial to
determine the ASD gauge fields, as in the case of ordinary caloron
construction. As an application of the q-deformed ADHMN construction, we give a
q-deformed caloron of Harrington-Shepard type. Some limits of the parameters
are also considered.Comment: 13 pages, No figure
Flux tubes and the type-I/type-II transition in a superconductor coupled to a superfluid
We analyze magnetic flux tubes at zero temperature in a superconductor that
is coupled to a superfluid via both density and gradient (``entrainment'')
interactions. The example we have in mind is high-density nuclear matter, which
is a proton superconductor and a neutron superfluid, but our treatment is
general and simple, modeling the interactions as a Ginzburg-Landau effective
theory with four-fermion couplings, including only s-wave pairing. We
numerically solve the field equations for flux tubes with an arbitrary number
of flux quanta, and compare their energies. This allows us to map the
type-I/type-II transition in the superconductor, which occurs at the
conventional kappa = 1/sqrt(2) if the condensates are uncoupled.
We find that a density coupling between the condensates raises the critical
kappa and, for a sufficiently high neutron density, resolves the type-I/type-II
transition line into an infinite number of bands corresponding to
``type-II(n)'' phases, in which n, the number of quanta in the favored flux
tube, steps from 1 to infinity. For lower neutron density, the coupling creates
spinodal regions around the type-I/type-II boundary, in which metastable flux
configurations are possible. We find that a gradient coupling between the
condensates lowers the critical kappa and creates spinodal regions. These
exotic phenomena may not occur in nuclear matter, which is thought to be deep
in the type-II region, but might be observed in condensed matter systems.Comment: 14 pages, improved discussion of the effects of varying the
neutron/proton condensate ratio; added reference
Giant vortices, vortex rings and reentrant behavior in type-1.5 superconductors
We predict that in a bulk type-1.5 superconductor the competing magnetic
responses of the two components of the order parameter can result in a vortex
interaction that generates group-stabilized giant vortices and unusual vortex
rings in the absence of any extrinsic pinning or confinement mechanism. We also
find within the Ginzburg-Landau theory a rich phase diagram with successions of
behaviors like type-1 -> type-1.5 -> type-2 -> type-1.5 as temperature
decreases.Comment: 5 pages, 4 figure
Expansion in the distance parameter for two vortices close together
Static vortices close together are studied for two different models in
2-dimen- sional Euclidean space. In a simple model for one complex field an
expansion in the parameters describing the relative position of two vortices
can be given in terms of trigonometric and exponential functions. The results
are then compared to those of the Ginzburg-Landau theory of a superconductor in
a magnetic field at the point between type-I and type-II superconductivity. For
the angular dependence a similar pattern emerges in both models. The
differences for the radial functions are studied up to third order.Comment: 14 pages, Late
Electric Flux Tube in Magnetic Plasma
In this paper we study a methodical problem related to the magnetic scenario
recently suggested and initiated by the authors \cite{Liao_ES_mono} to
understand the strongly coupled quark-gluon plasma (sQGP): the electric flux
tube in monopole plasma. A macroscopic approach, interpolating between Bose
condensed (dual superconductor) and classical gas medium is developed first.
Then we work out a microscopic approach based on detailed quantum mechanical
calculation of the monopole scattering on electric flux tube, evaluating
induced currents for all partial waves. As expected, the flux tube looses its
stability when particles can penetrate it: we make this condition precise by
calculating the critical value for the product of the flux tube size times the
particle momentum, above which the flux tube dissolves. Lattice static
potentials indicate that flux tubes seem to dissolve at . Using our criterion one gets an estimate of the magnetic
density at this temperature.Comment: New version with new referecences added and minor changes. 15 pages,
8 figure
A q-analog of the ADHMN construction and axisymmetric multi-instantons
In the preceding paper (Phys. Lett. B463 (1999) 257), the authors presented a
q-analog of the ADHMN construction and obtained a family of anti-selfdual
configurations with a parameter q for classical SU(2) Yang-Mills theory in
four-dimensional Euclidean space. The family of solutions can be seen as a
q-analog of the single BPS monopole preserving (anti-)selfduality. Further
discussion is made on the relation to axisymmetric ansatz on anti-selfdual
equation given by Witten in the late seventies. It is found that the
q-exponential functions familiar in q-analysis appear as analytic functions
categorizing the anti-selfdual configurations yielded by axisymmetric ansatz.Comment: 11pages, Latex2e, to appear in Journal of Physics A: Mathematical and
General as a `Special Issue/Difference Equations
Boundary Terms in Supergravity and Supersymmetry
We begin with the simplest possible introduction to supergravity. Then we
discuss its spin 3/2 stress tensor; these results are new. Next, we discuss
boundary conditions on fields and boundary actions for N=1 supergravity.
Finally, we discuss new boundary contributions to the mass and central charge
of monopoles in N=4 super Yang-Mills theory. All models are in 3+1 dimensions.Comment: 15 pages. Talk given by P. van Nieuwenhuizen at the
Einstein-celebration gravitational conference at Puri (India) in December
200
Z_3 Strings and their Interactions
We construct Z_3 vortex solutions in a model in which SU(3) is spontaneously
broken to Z_3. The model is truncated to one in which there are only two
dimensionless free parameters and the interaction of vortices within this
restricted set of models is studied numerically. We find that there is a curve
in the two dimensional space of parameters for which the energy of two
asymptotically separated vortices equals the energy of the vortices at
vanishing separation. This suggests that the inter-vortex potential for Z_3
strings might be flat for these couplings, much like the case of U(1) strings
in the Bogomolnyi limit. However, we argue that the intervortex potential is
attractive at short distances and repulsive at large separations leading to the
possibility of unstable bound states of Z_3 vortices.Comment: 8 pages; mainly corrected typos in table
Non-Abelian Vortices without Dynamical Abelianization
Vortices carrying truly non-Abelian flux moduli, which do not dynamically
reduce to Abelian vortices, are found in the context of softly-broken supersymmetric chromodynamics (SQCD). By tuning the bare quark masses
appropriately we identify the vacuum in which the underlying SU(N) gauge group
is partially broken to SU(n) \times SU(r) \times U(1)/{\mathbbm Z}_{K}, where
is the least common multiple of , and with and
flavors of light quark multiplets. At much lower energies the
gauge group is broken completely by the squark VEVs, and vortices develop which
carry non-Abelian flux moduli . For we argue
that the SU(n) fluctuations become strongly coupled and Abelianize, while
leaving weakly fluctuating flux moduli. This allows us to recognize the
semi-classical origin of the light non-Abelian monopoles found earlier in the
fully quantum-mechanical treatment of 4D SQCD.Comment: 22 pages, 4 figures, One section (Section 2) added, and an extended
discussion added in Section
CPT violation and particle-antiparticle asymmetry in cosmology
General features of generation of the cosmological charge asymmetry in CPT
non-invariant world are discussed. If the effects of CPT violation manifest
themselves only in mass differences of particles and antiparticles, the baryon
asymmetry of the universe hardly can be explained solely by breaking of CPT
invariance. However, CPT non-invariant theories may lead to a new effect of
distorting the usual equilibrium distributions. If this takes place, CPT
violation may explain the baryon asymmetry of the universe.Comment: 7 pages, no figures. Submitted to a special issue of Yadernaya Fizika
(Physics of Atomic Nuclei) dedicated to 80th birthday of L.B. Okun. Three
references are adde