1,017 research outputs found
Quantum power correction to the Newton law
We have found the graviton contribution to the one-loop quantum correction to
the Newton law. This correction results in interaction decreasing with distance
as 1/r^3 and is dominated numerically by the graviton contribution. The
previous calculations of this contribution to the discussed effect are
demonstrated to be incorrect.Comment: 10 pages, 5 figures; numerical error corrected, few references adde
On the Ultraviolet Behaviour of Newton's constant
We clarify a point concerning the ultraviolet behaviour of the Quantum Field
Theory of gravity, under the assumption of the existence of an ultraviolet
Fixed Point. We explain why Newton's constant should to scale like the inverse
of the square of the cutoff, even though it is technically inessential. As a
consequence of this behaviour, the existence of an UV Fixed Point would seem to
imply that gravity has a built-in UV cutoff when described in Planck units, but
not necessarily in other units.Comment: 8 pages; CQG class; minor changes and rearrangement
Annihilation, Rescattering, and CP Asymmetries in B Meson Decays
A number of meson decays may proceed only through participation of the
spectator quark, whether through amplitudes proportional to or via
rescattering from other less-suppressed amplitudes. An expected hierarchy of
amplitudes in the absence of rescattering will be violated by rescattering
corrections. Such violations could point the way toward channels in which
final-state interactions could be important. Cases in which final state phases
can lead to large CP asymmetries are pointed out.Comment: 9 page
Improvements to the Method of Dispersion Relations for B Nonleptonic Decays
We bring some clarifications and improvements to the method of dispersion
relations in the external masses variables, that we proposed recently for
investigating the final state interactions in the B nonleptonic decays. We
first present arguments for the existence of an additional term in the
dispersion representation, which arises from an equal-time commutator in the
LSZ formalism and can be approximated by the conventional factorized amplitude.
The reality properties of the spectral function and the Goldberger-Treiman
procedure to perform the hadronic unitarity sum are analyzed in more detail. We
also improve the treatment of the strong interaction part by including the
contributions of both t and u-channel trajectories in the Regge amplitudes.
Applications to the and decays are
presented.Comment: 16 pages, 4 new figures. modifications of the dispersion
representatio
Dispersion Relations and Rescattering Effects in B Nonleptonic Decays
Recently, the final state strong interactions in nonleptonic B decays were
investigated in a formalism based on hadronic unitarity and dispersion
relations in terms of the off-shell mass squared of the meson. We consider
an heuristic derivation of the dispersion relations in the mass variables using
the reduction LSZ formalism and find a discrepancy between the spectral
function and the dispersive variable used in the recent works. The part of the
unitarity sum which describes final state interactions is shown to appear as
spectral function in a dispersion relation based on the analytic continuation
in the mass squared of one final particles. As an application, by combining
this formalism with Regge theory and SU(3) flavour symmetry we obtain
constraints on the tree and the penguin amplitudes of the decay .Comment: 17 pages, Latex, 2 figure
Possibility of extracting the weak phase from decays
We explore the possibility of extracting the weak phase from pure
tree decays in a model
independent way. The CP violating weak phase can be determined
cleanly, without any hadronic uncertainties, as these decay modes are free from
the penguin pollutions. Furthermore, neither tagging nor time dependent studies
are required to extract the angle with these modes.Comment: 12 pages, LaTex, Minor changes in the text, version to appear in
Phys. Rev.
Pion Interactions in Chiral Field Theories
We study in various chiral models the pion charge radius, form
factor ratio, amplitude, charge pion
polarizabilities, amplitude at low
energies and the s-wave I = 0 scattering length. We find that a
quark-level linear sigma-model approach (also being consistent with tree-level
vector meson dominance) is quite compatible with all of the above data.Comment: 12 pages, 9 eps figure
Detecting new physics contributions to the D0-D0bar mixing through their effects on B decays
New physics effects may yield a detectable mass difference in the D0-D0bar
system, Delta m_D. Here we show that this has an important impact on some B -->
D decays. The effect involves a new source of CP violation, which arises from
the interference between the phases in the B --> D decays and those in the
D0-D0bar system. This interference is naturally large. New physics may well
manifest itself through Delta m_D contributions to these B decays.Comment: 10 pages, Revtex, no figures. To appear in PR
Improved Methods for Observing CP Violation in B+/- --> K+/- D0 and Measuring the CKM Phase gamma
Various methods are discussed for obtaining the CKM angle gamma through the
interference of the charged B-meson decay channels B- -> K- D0 and B- -> K-
D0-bar where the D0 and D0-bar decay to common final states. It is found that
choosing final states which are not CP eigenstates can lead to large direct CP
violation which can give significant bounds on gamma without any theoretical
assumptions. If two or more modes are studied, gamma may be extracted with a
precision on the order of +/-15 degrees given about 10^8 B-mesons. We also
discuss the case of three body decays of the D0 where additional information
may be obtained from the distribution of the D0 decay products and consider the
impact of D-D-bar oscillations.Comment: 51 pages 8 figures, typo in equation 33 correcte
Veneziano Ghost Versus Isospin Breaking
It is argued that an account for the Veneziano ghost pole, appearing in
resolving the U(1) problem, is necessary for understanding an isospin violation
in the system. By virtue of a perturbative expansion
around the ( ) symmetric Veneziano solution, we
find that the ghost considerably suppresses isospin breaking gluon and s-quark
matrix elements. We speculate further on a few cases where the proposed
mechanism can play an essential role. We discuss the isospin violation in
meson-nucleon couplings and its relevance to the problem of charge asymmetric
nuclear forces and possible breaking of the Bjorken sum rule. It is shown that
the ghost pole could yield the isospin violation of order 2 \% for the couplings and 20 \% for the
Bjorken sum rule.Comment: 16 pages , Preprint TAUP-2127-9
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