6,753 research outputs found
N=2 Supersymmetric Model with Dirac-Kahler Fermions from Generalized Gauge Theory in Two Dimensions
We investigate the generalized gauge theory which has been proposed
previously and show that in two dimensions the instanton gauge fixing of the
generalized topological Yang-Mills action leads to a twisted N=2 supersymmetric
action. We have found that the R-symmetry of N=2 supersymmetry can be
identified with the flavour symmetry of Dirac-Kahler fermion formulation. Thus
the procedure of twist allows topological ghost fields to be interpreted as the
Dirac-Kahler matter fermions.Comment: 22 pages, LaTe
Nuclear Physics from lattice QCD at strong coupling
We study numerically the strong coupling limit of lattice QCD with one flavor
of massless staggered quarks. We determine the complete phase diagram as a
function of temperature and chemical potential, including a tricritical point.
We clarify the nature of the low temperature dense phase, which is strongly
bound nuclear matter. This strong binding is explained by the nuclear
potential, which we measure. Finally, we determine, from this first-principle
limiting case of QCD, the masses of atomic nuclei up to A=12 "carbon".Comment: 4 pages, 5 figures; v2: references added, minor changes, published
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Inner products of resonance solutions in 1-D quantum barriers
The properties of a prescription for the inner products of the resonance
(Gamow states), scattering (Dirac kets), and bound states for 1-dimensional
quantum barriers are worked out. The divergent asypmtotic behaviour of the
Gamow states is regularized using a Gaussian convergence factor first
introduced by Zel'dovich. With this prescription, most of these states (with
discrete complex energies) are found to be orthogonal to each other, to the
bound states, and to the Dirac kets, except when they are neighbors, in which
case the inner product is divergent. Therefore, as it happens for the continuum
scattering states, the norm of the resonant ones remains non-calculable. Thus,
they exhibit properties half way between the (continuum real) Dirac-delta
orthogonality and the (discrete real) Kronecker-delta orthogonality of the
bound states.Comment: 13 pages, 2 figure
Microscopic analysis of the microscopic reversibility in quantum systems
We investigate the robustness of the microscopic reversibility in open
quantum systems which is discussed by Monnai [arXiv:1106.1982 (2011)]. We
derive an exact relation between the forward transition probability and the
reversed transition probability in the case of a general measurement basis. We
show that the microscopic reversibility acquires some corrections in general
and discuss the physical meaning of the corrections. Under certain processes,
some of the correction terms vanish and we numerically confirmed that the
remaining correction term becomes negligible; the microscopic reversibility
almost holds even when the local system cannot be regarded as macroscopic.Comment: 12 pages, 10 figure
Chiral Symmetry Breaking and Cooling in Lattice QCD
Chiral symmetry breaking is calculated as a function of cooling in quenched
lattice QCD. A non-zero signal is found for the chiral condensate beyond one
hundred cooling steps, suggesting that there is chiral symmetry breaking
associated with instantons. Quantitatively, the chiral condensate in cooled
gauge field configurations is small compared to the value without cooling.Comment: 11 pages in REVTEX including 4 PS figures embedded using psfig.sty,
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pion scattering amplitude with Wilson fermions
We present an exploratory calculation of the scattering
amplitude at threshold using Wilson fermions in the quenched approximation,
including all the required contractions. We find good agreement with the
predictions of chiral perturbation theory even for pions of mass 560-700 MeV.
Within the 10\% errors, we do not see the onset of the bad chiral behavior
expected for Wilson fermions. We also derive rigorous inequalities that apply
to 2-particle correlators and as a consequence show that the interaction in the
antisymmetric state of two pions has to be attractive.Comment: This PS file includes 4 tables and figures 1-8 on 25 pages. Los
Alamos Preprint Number LAUR-92-364
Substitution Effect by Deuterated Donors on Superconductivity in -(BEDT-TTF)Cu[N(CN)]Br
We investigate the superconductivity in the deuterated BEDT-TTF molecular
substitution system
-[(h8-BEDT-TTF)(d8-BEDT-TTF)]Cu[N(CN)]Br, where h8
and d8 denote fully hydrogenated and deuterated molecules, respectively.
Systematic and wide range ( = 0 -- 1) substitution can control chemical
pressure finely near the Mott boundary, which results in the modification of
the superconductivity. After cooling slowly, the increase of
observed up to 0.1 is evidently caused by the chemical pressure
effect. Neither reduction of nor suppression of
superconducting volume fraction is found below 0.5. This demonstrates
that the effect of disorder by substitution is negligible in the present
system. With further increase of , both and superconducting
volume fraction start to decrease toward the values in = 1.Comment: J. Phys. Soc. Jp
Detailed Structural Characterization of the Lipooligosaccharide from the Extracellular Membrane Vesicles of Shewanella vesiculosa HM13
Bacterial extracellular membrane vesicles (EMVs) are membrane-bound particles released during cell growth by a variety of microorganisms, among which are cold-adapted bacteria. Shewanella vesiculosa HM13, a cold-adapted Gram-negative bacterium isolated from the intestine of a horse mackerel, is able to produce a large amount of EMVs. S. vesiculosa HM13 has been found to include a cargo protein, P49, in the EMVs, but the entire mechanism in which P49 is preferentially included in the vesicles has still not been completely deciphered. Given these premises, and since the structural study of the components of the EMVs is crucial for deciphering the P49 transport mechanism, in this study the complete characterization of the lipooligosaccharide (LOS) isolated from the cells and from the EMVs of S. vesiculosa HM13 grown at 18 °C is reported. Both lipid A and core oligosaccharide have been characterized by chemical and spectroscopic methods
Mott Transition, Compressibility Divergence and P-T Phase Diagram of Layered Organic Superconductors: An Ultrasonic Investigation
The phase diagram of the organic superconductor
-(BEDT-TTF)Cu[N(CN)Cl has been investigated by ultrasonic
velocity measurements under helium gas pressure. Different phase transitions
were identified trough several elastic anomalies characterized from isobaric
and isothermal sweeps. Our data reveal two crossover lines that end on the
critical point terminating the first-order Mott transition line. When the
critical point is approached along these lines, we observe a dramatic softening
of the velocity which is consistent with a diverging compressibility of the
electronic degrees of freedom.Comment: 4 pages, 5 figure
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