37 research outputs found
Sparse Selfreducible Sets and Nonuniform Lower Bounds
It is well-known that the class of sets that can be computed by polynomial size circuits is equal to the class of sets that are polynomial time reducible to a sparse set. It is widely believed, but unfortunately up to now unproven, that there are sets in (Formula presented.), or even in (Formula presented.) that are not computable by polynomial size circuits and hence are not reducible to a sparse set. In this paper we study this question in a more restricted setting: what is the computational complexity of sparse sets that are selfreducible? It follows from earlier work of Lozano and Torán (in: Mathematical systems theory, 1991) that (Formula presented.) does not have sparse selfreducible hard sets. We define a natural version of selfreduction, tree-selfreducibility, and show that (Formula presented.) does not have sparse tree-selfreducible hard sets. We also construct an oracle relative to which all of (Formula presented.) is reducible to a sparse tree-selfreducible set. These lower bounds are corollaries of more general results about the computational complexity of sparse sets that are selfreducible, and can be interpreted as super-polynomial circuit lower bounds for (Formula presented.)
The Strong Coupling Constants of Excited Positive Parity Heavy Mesons in Light Cone QCD
We calculate the strong coupling constants g_(P^(**)P^(*)\pi), where
P^(**)(D^(**), B^(**)) is the 1^+ p-wave state, in the framework of the light
cone QCD sum rules, and using these values of g_(P^(**)P^(*) pi, we compute the
hadronic decay widths for D^(**) -> D^* pi and B^(**) -> B^* pi.Comment: 9 pages, LaTeX formatte
Yukawa structure, flavour and CP violation in Supergravity
The hierarchical structure of fermion masses and mixings strongly suggests an
underlying family symmetry. In supergravity any familon field spontaneously
breaking this symmetry necessarily acquires an F-term which contributes to the
soft trilinear couplings. We show, as a result, mu -> e gamma decay can receive
large contributions from this source at the level of current experimental
bounds and thus this channel may provide the first indication of supersymmetry
and a clue to the structure of the soft breaking sector. Using the mercury EDM
bounds we find strong bounds on the right handed down quark mixing angles that
are inconsistent with models relating them to neutrino mixing angles and favour
a near-symmetric form for the magnitude of the down quark mass matrix.Comment: Final version to appear in PRD. Improved discusion of several points,
updated references, typos correcte
On free 4D Abelian 2-form and anomalous 2D Abelian 1-form gauge theories
We demonstrate a few striking similarities and some glaring differences
between (i) the free four (3 + 1)-dimensional (4D) Abelian 2-form gauge theory,
and (ii) the anomalous two (1 + 1)-dimensional (2D) Abelian 1-form gauge
theory, within the framework of Becchi-Rouet-Stora-Tyutin (BRST) formalism. We
demonstrate that the Lagrangian densities of the above two theories transform
in a similar fashion under a set of symmetry transformations even though they
are endowed with a drastically different variety of constraint structures.
Taking the help of our understanding of the 4D Abelian 2-form gauge theory, we
prove that the gauge invariant version of the anomalous 2D Abelian 1-form gauge
theory is a new field-theoretic model for the Hodge theory where all the de
Rham cohomological operators of differential geometry find their physical
realizations in the language of proper symmetry transformations. The
corresponding conserved charges obey an algebra that is reminiscent of the
algebra of the cohomological operators. We briefly comment on the consistency
of the 2D anomalous 1-form gauge theory in the language of restrictions on the
harmonic state of the (anti-) BRST and (anti-) co-BRST invariant version of the
above 2D theory.Comment: LaTeX file, 37 pages, version to appear in EPJ
Measurement of spin correlation in ttbar production using dilepton final states
We measure the correlation between the spin of the top quark and the spin of
the anti-top quark in (ttbar -> W+ W- b bbar -> l+ nu b l- nubar bbar) final
states produced in ppbar collisions at a center of mass energy sqrt(s)=1.96
TeV, where l is an electron or muon. The data correspond to an integrated
luminosity of 5.4 fb-1 and were collected with the D0 detector at the Fermilab
Tevatron collider. The correlation is extracted from the angles of the two
leptons in the t and tbar rest frames, yielding a correlation strength C=
0.10^{+0.45}_{-0.45}, in agreement with the NLO QCD prediction within two
standard deviations, but also in agreement with the no correlation hypothesis.Comment: 10 pages, 3 figures, submitted to PL
Comportamento adjunto: controvérsias e contribuições teóricas
A área de investigação sobre comportamento adjunto, cujas pesquisas tiveram inĂcio na dĂ©cada de 60, Ă© extensa e controvertida. O presente trabalho analisa as interpretações mais importantes do fenĂ´meno, e mostra que diversas caracterĂsticas apresentadas como prĂłprias do comportamento adjunto tambĂ©m estĂŁo presentes em outros comportamentos. Falk interpretou o comportamento adjunto como atividade deslocada, Staddon como comportamento induzido por esquema, Timberlake como parte de um sistema comportamental prĂ©-programado, e Wetherington questionou a existĂŞncia de uma terceira classe de comportamento. Conclui-se que as tentativas de sistematização tĂŞm se mostrado incompletas devido Ă diversidade de topografias de comportamentos adjuntos e a sua dependĂŞncia de variáveis tanto do esquema como da espĂ©cie e do ambiente
Social Support, Source Credibility, Social Influence, and Impulsive Purchase Behavior in Social Commerce
Integration and individuality in healthy eating: meanings, values, and approaches of childless, dual earner couples
Consumption and emotion : the romantic ethic revisited
This article revisits Campbell's (1987) The Romantic Ethic and the Spirit of Modern Consumerism thesis in the light of new intersections with sociological issues of embodiment and emotions. A variety of themes and issues are raised the persistence of mind/body, reason,emotion dualities in the consumption literature, the importance of disappointment in consumer culture, external factors which mediate the consumption experience, and finally, the interpretation of both Romanticism and romantic interpersonal relationships. A largely disembodied and socially disembedded account of consumption and emotion is on offer here the implications of which extend far beyond the limits of Campbell's thesis to debates on consumer culture and the sociological enterprise in general in making these claims, we highlight the need for a passionate sociology which would in turn integrate embodiment and emotions more fully into the consumption agenda. These key themes are discussed with some sociological pointers for the future in consumption and beyond