23 research outputs found
Novel Spin and Statistical Properties of Nonabelian Vortices
We study the statistics of vortices which appear in (2+1)--dimensional
spontaneously broken gauge theories, where a compact group G breaks to a finite
nonabelian subgroup H. Two simple models are presented. In the first, a quantum
state which is symmetric under the interchange of a pair of indistinguishable
vortices can be transformed into an antisymmetric state after the passage
through the system of a third vortex with an appropriate -flux element.
Further, there exist states containing two indistinguishable spinless vortices
which obey Fermi statistics. These results generalize to loops of nonabelian
cosmic string in 3+1 dimensions. In the second model, fractional analogues of
the above behaviors occur. Also, composites of vortices in this theory may
possess fractional ``Cheshire spin'' which can be changed by passing an
additional vortex through the system.Comment: 11 pages, UICHEP-TH/92-15; FERMILAB-PUB-92/233-T; SLAC-PUB-588
Lepto-mesons, Leptoquarkonium and the QCD Potential
We consider bound states of heavy leptoquark-antiquark pairs (lepto-mesons)
as well as leptoquark-antileptoquark pairs (leptoquarkonium). Unlike the
situation for top quarks, leptoquarks (if they exist) may live long enough for
these hadrons to form. We study the spectra and decay widths of these states in
the context of a nonrelativistic potential model which matches the recently
calculated two-loop QCD potential at short distances to a successful
phenomenological quarkonium potential at intermediate distances. We also
compute the expected number of events for these states at future colliders.Comment: 12 pages, 1 figure, 3 tables, plain TeX, requires harvmac. References
updated and minor clarifications made. To appear in Physics Letters
Nonabelian Vortices on Surfaces and Their Statistics
We discuss the physics of topological vortices moving on an arbitrary surface
M in a Yang-Mills-Higgs theory in which the gauge group G breaks to a finite
subgroup H. We concentrate on the case where M is compact and/or nonorientable.
Interesting new features arise which have no analog on the plane. The
consequences for the quantum statistics of vortices are discussed, particularly
when H is nonabelian.Comment: 27 pages, 6 figures, requires harvma
Simple Baryon-Meson Mass Relations For A Logarithmic Interquark Potential
I consider the quantity delta(m_1m_2m_3) = M_{q_1q_2q_3} - [M_{q_1q_2bar} +
M_{q_2q_3bar} + M_{q_1q_3bar}]/2, where the M's represent the ground state
spin-averaged hadron masses with the indicated quark content and the m's the
corresponding constituent quark masses. I assume a logarithmic interquark
potential, the validity of a nonrelativistic approach, and various standard
potential model inputs. Simple scaling arguments then imply that the quantity
R(x)=delta(mmm_3)/delta(m_0m_0m_0) depends only on the ratio x=m/m_3, and is
independent of m_0 as well as any parameters appearing in the potential. A
simple and accurate analytic determination of delta(mmm_3), and hence R(x), is
given using the 1/D expansion where D is the number of spatial dimensions. When
applicable, this estimate of R(x) compares very well to experiment -- even for
hadrons containing light quarks. A prediction of the above result which is
likely to be tested in the near future is M_{Sigma_b^*}/2 + [M_{Lambda_b} +
M_{Sigma_b}]/4 = 5774 +/- 4 MeV/c^2.Comment: 13 pages, plain TeX, 1 eps figure, uses harvmac and epsf.st
Resonant Bound State Production at e- e- Colliders
Observation of a sequence of resonances at an e-e- collider would suggest
bound states of strongly coupled constituents carrying lepton number. Obvious
candidates for these exotic constituents are leptoquarks and leptogluons. We
show that under reasonable assumptions, the existence of one leptogluon flavor
of appropriate mass can give rise to sizeable ``leptoglueball'' production
rates and observable resonance peaks. In contrast, one needs two leptoquark
flavors in order to produce the analogous ``leptoquarkonium'' states. Moreover,
cross-generational leptoquark couplings are necessary to give observable event
rates in many cases, and leptoquarkonium mass splittings are too small to
resolve with realistic beam energy resolutions.Comment: 8 pages, 1 table, plain TeX, requires harvmac. Brief comparison to
leptoglueball production at e+e- colliders added. Other minor changes. To
appear in Physics Letters
Spinning Particles, Braid Groups and Solitons
We develop general techniques for computing the fundamental group of the
configuration space of identical particles, possessing a generic internal
structure, moving on a manifold . This group generalizes the -string
braid group of which is the relevant object for structureless particles. In
particular, we compute these generalized braid groups for particles with an
internal spin degree of freedom on an arbitrary . A study of their unitary
representations allows us to determine the available spectrum of spin and
statistics on in a certain class of quantum theories. One interesting
result is that half-integral spin quantizations are obtained on certain
manifolds having an obstruction to an ordinary spin structure. We also compare
our results to corresponding ones for topological solitons in
-invariant nonlinear sigma models in -dimensions, generalizing
recent studies in two spatial dimensions. Finally, we prove that there exists a
general scalar quantum theory yielding half-integral spin for particles (or
solitons) on a closed, orientable manifold if and only if
possesses a structure.Comment: harvmac, 34 pages, HUTP-93/A037; UICHEP-TH/93-18; BUHEP-93-2
Topology Change and theta-Vacua in 2D Yang-Mills Theory
We discuss the existence of -vacua in pure Yang-Mills theory in two
space-time dimensions. More precisely, a procedure is given which allows one to
classify the distinct quantum theories possessing the same classical limit for
an arbitrary connected gauge group G and compact space-time manifold M
(possibly with boundary) possessing a special basepoint. For any such G and M
it is shown that the above quantizations are in one-to-one correspondence with
the irreducible unitary representations (IUR's) of if M is
orientable, and with the IUR's of if M is nonorientable.Comment: 16 pages, 4 figures, uses harvmac and psbo