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Physical Sciences and Mathematics Commons™
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Articles 1 - 5 of 5
Full-Text Articles in Physical Sciences and Mathematics
Breaking Cosmic Strings Without Monopoles, D Eardley, G Horowitz, David Kastor, Jennie Traschen
Breaking Cosmic Strings Without Monopoles, D Eardley, G Horowitz, David Kastor, Jennie Traschen
Physics Department Faculty Publication Series
It is shown that topologically stable cosmic strings can, in fact, appear to end or to break, even in theories without monopoles. This can occur whenever the spatial topology of the universe is nontrivial. For the case of Abelian-Higgs strings, we describe the gauge and scalar field configurations necessary for a string to end on a black hole. We give a lower bound for the rate at which a cosmic string will break via black hole pair production, using an instanton calculation based on the Euclidean C-metric.
Calculation Of A Weak Nonleptonic Matrix Element Using “Weinberg” Sum Rules, John Donoghue
Calculation Of A Weak Nonleptonic Matrix Element Using “Weinberg” Sum Rules, John Donoghue
Physics Department Faculty Publication Series
There is a ``toy'' weak matrix element which can be expressed as an integral over the vector and axial vector spectral functions, $\rho_V (s) - \rho_A (s)$. I review our recent evaluation of these spectral functions, the study of four ``Weinberg'' sum rules and the calculation of this matrix element.
Reanalysis Of The Decay-K-L-]Pi(0)E(+)E(-), Jf Donoghue, F Gabbiani
Reanalysis Of The Decay-K-L-]Pi(0)E(+)E(-), Jf Donoghue, F Gabbiani
Physics Department Faculty Publication Series
The decay KL→π0e+e- is searched for as a signal of direct ΔS=1 CP violation. We provide a thorough updating of the analysis of the three components of the decay: (1) direct CP violation, (2) CP violation through the mass matrix, and (3) CP-conserving (two photon) contributions. First the chiral calculation of the KS→π0e+e- rate, due to Ecker, Pich and, de Rafael, is updated to include recent results on the nonleptonic amplitude. Then we systematically explore the uncertainties in this method. These appear to be so large that they will obscure direct CP violation unless it is possible to measure the …
Dispersion Relations And Effective Field Theory, John Donoghue
Dispersion Relations And Effective Field Theory, John Donoghue
Physics Department Faculty Publication Series
The techniques of dispersion relations match very well with those of effective field theory. I describe the techniques for using dispersion relations effectively, and give some pedagogical examples to illustrate the range of applications.
On The Marriage Of Chiral Perturbation Theory And Dispersion Relations, John Donoghue
On The Marriage Of Chiral Perturbation Theory And Dispersion Relations, John Donoghue
Physics Department Faculty Publication Series
I describe the methodology for the use of dispersion relations in connection with chiral perturbation theory. The conditions for matching the two formalisms are given at $O(E^2)$ and $O(E^4)$. The two have several complementary features, as well as some limitations, and these are described by the use of examples, which include chiral sum rules related to the Weinberg sum rules, form factors, and a more complicated reaction, $\gamma \gamma \rightarrow \pi \pi$.