3,168 research outputs found
Critical O(N) - vector nonlinear sigma - models: A resume of their field structure
The classification of quasi - primary fields is outlined. It is proved that
the only conserved quasi - primary currents are the energy - momentum tensor
and the O(N) - Noether currents. Derivation of all quasi - primary fields and
the resolution of degeneracy is sketched. Finally the limits d=2 and d=4 of the
space dimension are discussed. Whereas the latter is trivial the former is only
almost so.Comment: 16 pages, Latex. To appear in the Proceedings of the XXII Conference
on Differential Methods in Theoretical Physics, Ixtapa, Mexico, September
20-24, 199
The Effect of Luxury Taxes on Competitive Balance, Club Profits, and Social Welfare in Sports Leagues
This paper provides a game-theoretic model of a professional sports league and analyzes the effect of luxury taxes on competitive balance, club profits and social welfare. We show that a luxury tax increases aggregate salary payments in the league as well as produces a more balanced league. Moreover, a higher tax rate increases the profits of large-market clubs, whereas the profits of small-market clubs only increase if the tax rate is not set inadequately high. Finally, we show that social welfare increases with a luxury tax.Sports League, Luxury Tax, Social Welfare, Competitive Balance
Chandra and FUSE spectroscopy of the hot bare stellar core H1504+65
H1504+65 is an extremely hot hydrogen-deficient white dwarf with an effective
temperature close to 200,000 K. We present new FUV and soft X-ray spectra
obtained with FUSE and Chandra, which confirm that H1504+65 has an atmosphere
primarily composed of carbon and oxygen. The Chandra LETG spectrum (60-160
Angstroem) shows a wealth of photospheric absorption lines from highly ionized
oxygen, neon, and - for the first time identified in this star - magnesium and
suggests relatively high Ne and Mg abundances. This corroborates an earlier
suggestion that H1504+65 represents a naked C/O stellar core or even the C/O
envelope of an O-Ne-Mg white dwarf.Comment: 15 pages, 10 figures, accepted for publication in A&
Efficient DMFT-simulation of the Holstein-Hubbard Model
We present a method for solving impurity models with electron-phonon
coupling, which treats the phonons efficiently and without approximations. The
algorithm is applied to the Holstein-Hubbard model in the dynamical mean field
approximation, where it allows access to strong interactions, very low
temperatures and arbitrary fillings. We show that a renormalized
Migdal-Eliashberg theory provides a reasonlable description of the phonon
contribution to the electronic self energy in strongly doped systems, but fails
if the quasiparticle energy becomes of order of the phonon frequency.Comment: Published versio
Monopole currents and Dirac sheets in U(1) lattice gauge theory
We show that the phases of the 4-dimensional compact U(1) lattice gauge
theory are unambiguously characterized by the topological properties of minimal
Dirac sheets as well as of monopole currents lines. We obtain the minimal
sheets by a simulated-annealing procedure. Our results indicate that the
equivalence classes of sheet structures are the physical relevant quantities
and that intersections are not important. In conclusion we get a
percolation-type view of the phases which holds beyond the particular boundary
conditions used.Comment: 13 pages, latex, 5 figures include
The group approach to AdS space propagators
We show that AdS two-point functions can be obtained by connecting two points
in the interior of AdS space with one point on its boundary by a dual pair of
Dobrev's boundary-to-bulk intertwiners and integrating over the boundary point.Comment: 23 page
Low-energy models for correlated materials: bandwidth renormalization from Coulombic screening
We provide a prescription for constructing Hamiltonians representing the low
energy physics of correlated electron materials with dynamically screened
Coulomb interactions. The key feature is a renormalization of the hopping and
hybridization parameters by the processes that lead to the dynamical screening.
The renormalization is shown to be non-negligible for various classes of
correlated electron materials. The bandwidth reduction effect is necessary for
connecting models to materials behavior and for making quantitative predictions
for low-energy properties of solids.Comment: 4 pages, 2 figure
On the proposed AdS dual of the critical O(N) sigma model for any dimension 2<d<4
We evaluate the 4-point function of the auxiliary field in the critical O(N)
sigma model at O(1/N) and show that it describes the exchange of tensor
currents of arbitrary even rank l>0. These are dual to tensor gauge fields of
the same rank in the AdS theory, which supports the recent hypothesis of
Klebanov and Polyakov. Their couplings to two auxiliary fields are also
derived.Comment: 14 page
Fractional Multi-Trace Fields of N=4 SYM_4 from AdS/CFT
We prove inductively that every k-trace operator of SO(6)_R irrep with Young
tableau partition {r_1,r_2,r_3}, constructed out of k chiral primaries in the
twenty dimensional SO(6)_R irrep, leads to a quasi primary field with protected
conformal dimension. Our argument is based on perturbative evaluations of
certain four point functions up to order 1/N^2.Comment: 14 pages, 6 figures, revised version, essential changes, to appear in
Physics Letters
Social Welfare in Sports Leagues with Profit-Maximizing and/or Win-Maximizing Clubs
This paper develops a contest model to compare social welfare in homogeneous leagues in which all clubs maximize identical objective functions with mixed leagues in which clubs maximize different objective functions. We show that homogeneous leagues in which all clubs are profit-maximizers dominate all other leagues whereas mixed leagues in which small-market clubs are profit- and large-market clubs are win-maximizers (type-I mixed leagues) are dominated by all other leagues. In addition, we show that, from a welfare perspective, large-market clubs win too often in (purely) win-maximizing and type-I mixed leagues whereas small-market clubs win too many games in (purely) profit-maximizing leagues and in mixed leagues in which large-market clubs are profit- and small-market clubs are win-maximizers (type-II mixed leagues). These results have important policy implications: Social welfare will increase if clubs are reorganized from non-profit members associations to profit-maximizing corporations. Moreover, it is socially desirable to reorganize large-market clubs first because, in mixed leagues, it is better if large-market clubs maximize profits instead of small-market clubs. Finally, we show that the invariance proposition does not hold in any league. In mixed (homogeneous) leagues, revenue sharing decreases (increases) social welfare. Given these results, homogeneous leagues should introduce revenue sharing; mixed leagues should not.Social welfare, team sports leagues, objective functions, mixed leagues, competitive balance
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