341 research outputs found
Chiral perturbation theory in a theta vacuum
We consider chiral perturbation theory (ChPT) with a non-zero theta term. Due
to the CP violating term, the vacuum of chiral fields is shifted to a
non-trivial element on the SU(N_f) group manifold. The CP violation also
provides mixing of different CP eigenstates, between scalar and pseudoscalar,
or vector and axialvector operators. We investigate upto O(theta^2) effects on
the mesonic two point correlators of ChPT to the one-loop order. We also
address the effects of fixing topology, by using saddle point integration in
the Fourier transform with respect to theta.Comment: 31 pages, references added, minor corrections, version published in
PR
Heavy-quark axial charges to non-leading order
We combine Witten's renormalization group with the matching conditions of
Bernreuther and Wetzel to calculate at next-to-leading order the complete
heavy-quark contribution to the neutral-current axial-charge measurable in
neutrino-proton elastic scattering. Our results are manifestly renormalization
group invariant.Comment: 5 pages, revtex styl
Poincar\'e recurrence theorem and the strong CP-problem
The existence in the physical QCD vacuum of nonzero gluon condensates, such
as , requires dominance of gluon fields with finite mean action
density. This naturally allows any real number value for the unit ``topological
charge'' characterising the fields approximating the gluon configurations
which should dominate the QCD partition function. If is an irrational
number then the critical values of the parameter for which CP is
spontaneously broken are dense in , which provides for a mechanism
of resolving the strong CP problem simultaneously with a correct implementation
of symmetry. We present an explicit realisation of this
mechanism within a QCD motivated domain model. Some model independent arguments
are given that suggest the relevance of this mechanism also to genuine QCD.Comment: 8 pages, RevTeX, 3 figures. Revised after referee suggestions. Now
includes model independent argument
Gluon topology and the spin structure of the constituent quark
Gluon topology makes a potentially important contribution to the spin of the
constituent quark.Comment: 3 pages, LaTeX, talk at DIS99, Zeuthen, April 199
Running couplings for the simultaneous decoupling of heavy quarks
Scale-invariant running couplings are constructed for several quarks being
decoupled together, without reference to intermediate thresholds.
Large-momentum scales can also be included. The result is a multi-scale
generalization of the renormalization group applicable to any order.
Inconsistencies in the usual decoupling procedure with a single running
coupling can then be avoided, e.g. when cancelling anomalous corrections from
t,b quarks to the axial charge of the proton.Comment: 12 pages, 1 figure, version to appear in PLB. Pages 8-11 and Fig. 1
are new, with consequent changes to the abstract, page 2, and the references.
We show that our multi-scale renormalization group is needed to achieve
anomaly cancellation in t,b decoupling from the weak neutral current, and
extend it to include large moment
The Measure of Strong CP Violation
We investigate a controversial issue on the measure of CP violation in strong
in teractions. In the presence of nontrivial topological gauge configurations,
the -term in QCD has a profound effect: it breaks the CP symmetry. The
CP-violating amplitude is shown to be determined by the vacuum tunneling
process, where the semiclassical method makes most sense. We discuss a
long-standing dispute on whether the instanton dynamics satisfies or not the
anomalous Ward identity (AWI). The strong CP violation measure, when complying
with the vacuum alignment, is proportional to the topological susceptibility.
We obtain an effective CP-violating lagrangian different from that provided by
Baluni. To solve the IR divergence problem of the instanton computation, We
present a ``classically gauged'' Georgi-Manohar model and derive an effective
potential which uniquely determines an explicit symmetry breaking
sector. The CP violation effects are analyzed in this model. It is shown that
the strong CP problem and the problem are closely related. Some possible
solutions to both problems are also discussed with new insights.Comment: 37 pages in LateX, SFU-Preprint-92-
Anomalous commutators and electroweak baryogenesis
Electroweak vacuum transition processes (sphalerons) in the early Universe
provide a possible explanation of the baryon asymmetry. Combining this physics
with the anomalous commutators of Adler and Boulware and renormalization group
invariance, we argue that electroweak baryon number violation also induces a
``topological condensate'' in the vacuum. QCD sphaleron processes act to
distribute the baryon number violation between both left and right handed
quarks and induce a spin independent component in this ``condensate''.Comment: 9 page
Techniques used to search for a permanent electric dipole moment of the 199 Hg atom and the implications for CP violation
No description supplie
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