987 research outputs found
Topological aspects in non-Abelian gauge theory
We discuss the BRST cohomology and exhibit a connection between the Hodge
decomposition theorem and the topological properties of a two dimensional free
non-Abelian gauge theory having no interaction with matter fields. The
topological nature of this theory is encoded in the vanishing of the Laplacian
operator when equations of motion are exploited. We obtain two sets of
topological invariants with respect to BRST and co-BRST charges on the two
dimensional manifold and show that the Lagrangian density of the theory can be
expressed as the sum of terms that are BRST- and co-BRST invariants.Comment: (1+11) pages, LaTeX, no figure
Field dependent nilpotent symmetry for gauge theories
We construct the field dependent mixed BRST (combination of BRST and
anti-BRST) transformations for pure gauge theories. These are shown to be an
exact nilpotent symmetry of both the effective action as well as the generating
functional for certain choices of the field dependent parameters. We show that
the Jacobian contributions for path integral measure in the definition of
generating functional arising from BRST and anti-BRST part compensate each
other. The field dependent mixed BRST transformations are also considered in
field/antifield formulation to show that the solutions of quantum master
equation remain invariant under these. Our results are supported by several
explicit examples.Comment: 25 pages, No figures, Revte
Superfield Approach To Nilpotent Symmetries For QED From A Single Restriction: An Alternative To The Horizontality Condition
We derive together the exact local, covariant, continuous and off-shell
nilpotent Becchi-Rouet-Stora-Tyutin (BRST) and anti-BRST symmetry
transformations for the U(1) gauge field (A_\mu), the (anti-)ghost fields
((\bar C)C) and the Dirac fields (\psi, \bar\psi) of the Lagrangian density of
a four (3 + 1)-dimensional QED by exploiting a single restriction on the six
(4, 2)-dimensional supermanifold. A set of four even spacetime coordinates
x^\mu (\mu = 0, 1, 2, 3) and two odd Grassmannian variables \theta and
\bar\theta parametrize this six dimensional supermanifold. The new gauge
invariant restriction on the above supermanifold owes its origin to the (super)
covariant derivatives and their intimate relations with the (super) 2-form
curvatures (\tilde F^{(2)})F^{(2)} constructed with the help of (super) 1-form
gauge connections (\tilde A^{(1)})A^{(1)} and (super) exterior derivatives
(\tilde d)d. The results obtained separately by exploiting (i) the
horizontality condition, and (ii) one of its consistent extensions, are shown
to be a simple consequence of this new single restriction on the above
supermanifold. Thus, our present endeavour provides an alternative to (and, in
some sense, generalization of) the horizontality condition of the usual
superfield formalism applied to the derivation of BRST symmetries.Comment: LaTeX file, 15 pages, journal-versio
Interacting Vector-Spinor and Nilpotent Supersymmetry
We formulate an interacting theory of a vector-spinor field that gauges
anticommuting spinor charges \{Q_\alpha{}^I, Q_\beta{}^J \} = 0 in arbitrary
space-time dimensions. The field content of the system is (\psi_\mu{}^{\alpha
I}, \chi^{\alpha I J}, A_\mu{}^I), where \psi_\mu{}^{\alpha I} is a
vector-spinor in the adjoint representation of an arbitrary gauge group, and
A_\mu{}^I is its gauge field, while \chi^{\alpha I J} is an extra spinor with
antisymmetric adjoint indices I J. Amazingly, the consistency of the
vector-spinor field equation is maintained, despite its non-trivial
interactions.Comment: 10 pages, no figure
Excited hadrons on the lattice: Mesons
We present results for masses of excited mesons from quenched calculations
using chirally improved quarks at pion masses down to 350 MeV. The key features
of our analysis are the use of a matrix of correlators from various source and
sink operators and a basis which includes quark sources with different spatial
widths, thereby improving overlap with states exhibiting radial excitations.Comment: 8 pages, 8 figures; version accepted to PR
Limits on Lorentz Violation from the Highest Energy Cosmic Rays
We place several new limits on Lorentz violating effects, which can modify
particles' dispersion relations, by considering the highest energy cosmic rays
observed. Since these are hadrons, this involves considering the partonic
content of such cosmic rays. We get a number of bounds on differences in
maximum propagation speeds, which are typically bounded at the 10^{-21} level,
and on momentum dependent dispersion corrections of the form v = 1 +-
p^2/Lambda^2, which typically bound Lambda > 10^{21} GeV, well above the Planck
scale. For (CPT violating) dispersion correction of the form v = 1 + p/Lambda,
the bounds are up to 15 orders of magnitude beyond the Planck scale.Comment: 24 pages, no figures. Added references, very slight changes. Version
published in Physical Review
Lattice energy-momentum tensor with Symanzik improved actions
We define the energy-momentum tensor on lattice for the and
for the nonlinear -model Symanzik tree-improved actions, using Ward
identities or an explicit matching procedure. The resulting operators give the
correct one loop scale anomaly, and in the case of the sigma model they can
have applications in Monte Carlo simulations.Comment: Self extracting archive fil
Ist Personenwahrnehmung im Attributionsgeschehen abhängig vom Ort der Erhebung?
Als zentraler Befund der ersten Untersuchung der einflussreichen Arbeit von Heider und Simmel [Am. J. Psychol., 57, 243-59 (1944)] zeigte sich, dass bewegte geometrische Objekte ganz überwiegend als Lebewesen wahrgenommen werden und diese wiederum meist als Personen. Da die Originaluntersuchung, die am Smith College für Psychologie durchgeführt wurde, nur Frauen miteinbezog und die Ergebnisse keine genauen Angaben zur Häufigkeit personaler Kausalität beinhalten, werden zwei Replikationen durchgeführt, um die Befunde auf eine breiter generalisierbare Basis zu stellen. In Studie eins wird die Untersuchung unter Verwendung des Originalversuchsmaterials an einer technischen Hochschule an Nichtpsychologen durchgeführt. Es zeigt sich auch bei konservativer Analyse, dass geschlechtsunabhängig weniger als 35 % der Teilnehmenden die Objekte als Lebewesen beschreiben. Von denjenigen, die die Objekte als beseelt wahrnehmen, werden diese in 80 % der Fälle als Menschen bezeichnet. Um eine mögliche Erklärung dieser deutlichen Abweichungen von den Originalbefunden zu finden, wird Studie zwei in Entsprechung zur Originalarbeit an einem Institut für Psychologie ausschließlich an Psychologiestudierenden durchgeführt. Jedoch zeigen sich auch hier identische Befunde. Somit konnten in zwei Replikationen zentrale Befunde der klassischen Arbeit nicht repliziert werden. Die Verwendung einer selektiven Stichprobe in unterschiedlichen Umgebungen erklärt nicht die klassischen Resultate
Planning and meta‑planning to cope with disruptive events: what can be learnt from the institutional response to the Covid‑19 pandemic in Italy
Fully double-logarithm-resummed cross sections
We calculate the complete double logarithmic contribution to cross sections
for semi-inclusive hadron production in the modified minimal-subtraction scheme
by applying dimensional regularization to the double logarithm approximation.
The full double logarithmic contribution to the coefficient functions for
inclusive hadron production in electron-positron annihilation is obtained in
this scheme for the first time. Our result agrees with all fixed order results
in the literature, which extend to next-next-to-leading order.Comment: To appear in Nuclear Physics
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