16,214,701 research outputs found
c=1 String Theory as a Topological G/G Model
The physical states on the free field Fock space of the {SL(2,R)\over
SL(2,R) model at any level are computed. Using a similarity transformation on
, the cohomology of the latter is mapped into a direct sum of simpler
cohomologies. We show a one to one correspondence between the states of the
model and those of the string model. A full equivalence between
the {SL(2,R)\over SL(2,R) and {SL(2,R)\over U(1) models at the level of
their Fock space cohomologies is found.Comment: 19
-odometers and their almost 1-1 extensions
In this paper we recall the concepts of -odometer and -subodometer for
-actions, where is a discrete finitely generated group, which generalize
the notion of odometer in the case G=\ZZ. We characterize the -regularly
recurrent systems as the minimal almost 1-1 extensions of subodometers, from
which we deduce that the family of the -Toeplitz subshifts coincides with
the family of the minimal symbolic almost 1-1 extensions of subodometers.Comment: 18 page
g=1 for Dirichlet 0-branes
Dirichlet 0-branes, considered as extreme Type IIA black holes with spin
carried by fermionic hair, are shown to have the anomalous gyromagnetic ratio
g=1, consistent with their interpretation as Kaluza-Klein modes.Comment: 13 pages, Late
The I^G J^{PC}=1^- 1^{-+} Tetraquark States
We study the tetraquark states with I^G J^{PC}=1^- 1^{-+} in the QCD sum
rule. After exhausting all possible flavor structures, we analyses both the SVZ
and finite energy sum rules. Both approaches lead to a mass around 1.6 GeV for
the state with the quark contents q q q_bar q_bar, and around 2.0 GeV for the
state with the quark contents q s q_bar s_bar. The flavor structure 3_bar *
6_bar + 6 * 3 is preferred. Our analysis strongly indicates that both pi1(1600)
and pi1(2015) are also compatible with the exotic tetraquark interpretation,
which are sometimes labeled as candidates of the 1^{-+} hybrid mesons. Moreover
one of their dominant decay modes is a pair of axial-vector and pseudoscalar
mesons such as b1(1235) pi, which is sometimes considered as the characteristic
decay mode of the hybrid mesons.Comment: 18 pages, 14 figures, revised version to appear in Phys. Rev.
The pressure of hot QCD up to g^6 ln(1/g)
The free energy density, or pressure, of QCD has at high temperatures an
expansion in the coupling constant g, known so far up to order g^5. We compute
here the last contribution which can be determined perturbatively, g^6 ln(1/g),
by summing together results for the 4-loop vacuum energy densities of two
different three-dimensional effective field theories. We also demonstrate that
the inclusion of the new perturbative g^6 ln(1/g) terms, once they are summed
together with the so far unknown perturbative and non-perturbative g^6 terms,
could potentially extend the applicability of the coupling constant series down
to surprisingly low temperatures.Comment: 18 pages. Small clarifications added. To appear in Phys.Rev.
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