43 research outputs found
The anomalous threshold, confinement, and an essential singularity in the heavy-light form factor
The analytic behavior of the heavy-light meson form factor is investigated
using several relativistic examples including unconfined, weakly confined, and
strongly confined mesons. It is observed that confinement erases the anomalous
threshold singularity and also induces an essential singularity at the normal
annihilation threshold. In the weak confinement limit, the "would be" anomalous
threshold contribution is identical to that of the real singularity on its
space-like side.Comment: Latex 2.09 with epsf.sty. 24 pages of text and 8 postscript figures.
Postscript version of complete paper will also be available soon at
http://phenom.physics.wisc.edu/pub/preprints/1997/madph-97-983 or at
ftp://phenom.physics.wisc.edu/pub/preprints/1997/madph-97-98
CP violation in chargino decays in the MSSM
In the minimal supersymmetric standard model (MSSM) with complex parameters,
supersymmetric loop effects can lead to \emph{CP} violation. We calculate the
rate asymmetries of decays of charginos into the lightest neutralino and a
boson on the basis of the most important loop contributions in the third
generation squark sectors. It turns out that the \emph{CP} violating
asymmetries can be a few per cent in typical regions of the parameter space of
the MSSM. These processes would provide very promising channels for probing
\emph{CP} violation in the MSSM at future high-energy colliders.Comment: 15 pages, 5 figures, LaTeX2
Electric Dipole Moments Do Not Require the CP-violating Phases of Supersymmetry To Be Small
We report the first fully general numerical calculation of the neutron and
electron dipole moments, including the seven significant phases. We find that
there are major regions in the parameter space where none of the phases are
required to be small, contrary to the conventional wisdom. The electric dipole
moments (EDM's) do provide useful constraints, allowing other regions of
parameter space to be carved away. We keep all superpartner masses light so
agreement with experimental limits arises purely from interesting relations
among soft breaking parameters.Comment: 23 pages, 7 figures; 2 references adde
Wide shear zones and the spot model: Implications from the split-bottom geometry
The spot model has been developed by Bazant and co-workers to describe
quasistatic granular flows. It assumes that granular flow is caused by the
opposing flow of so-called spots of excess free volume, with spots moving along
the slip lines of Mohr-Coulomb plasticity. The model is two-dimensional and has
been successfully applied to a number of different geometries. In this paper we
investigate whether the spot model in its simplest form can describe the wide
shear zones observed in experiments and simulations of a Couette cell with
split bottom. We give a general argument that is independent of the particular
description of the stresses, but which shows that the present formulation of
the spot model in which diffusion and drift terms are postulated to balance on
length scales of order of the spot diameter, i.e. of order 3-5 grain diameters,
is difficult to reconcile with the observed wide shear zones. We also discuss
the implications for the spot model of co-axiality of the stress and strain
rate tensors found in these wide shear flows, and point to possible extensions
of the model that might allow one to account for the existence of wide shear
zones.Comment: 6 pages, 6 figures, to be published in EPJ
Electron and Neutron Electric Dipole Moments in the Constrained MSSM
We analyze the effects of CP-violating phases on the electric dipole moment
(EDM) of electron and neutron in the constrained minimal supersymmetric model.
We find that the phases phi_{\mu} and phi_{A_0} have to be strongly correlated,
in particular for small values of the SUSY mass parameters. We calculate the
neutron EDM in two different models, the Quark-Parton Model and the Chiral
Quark Model. It turns out that the predictions are quite sensitive to the model
used. We show parameter regions in the M_0-M_1/2 plane which are excluded by
considering simultaneously the experimental bounds of both electron and neutron
EDM, assuming specific values for the phases phi_{\mu} and phi_{A_0}.Comment: 23 pages LaTeX with 8 figures included, using the epsfig-stylefil
Non-local rheology in dense granular flows -- Revisiting the concept of fluidity
Granular materials belong to the class of amorphous athermal systems, like foams, emulsion or suspension they can resist shear like a solid, but flow like a liquid under a sufficiently large applied shear stress. They exhibit a dynamical phase transition between static and flowing states, as for phase transitions of thermodynamic systems, this rigidity transition exhibits a diverging length scales quantifying the degree of cooperatively. Several experiments have shown that the rheology of granular materials and emulsion is non-local, namely that the stress at a given location does not depend only on the shear rate at this location but also on the degree of mobility in the surrounding region. Several constitutive relations have recently been proposed and tested successfully against numerical and experimental results. Here we use discrete elements simulation of 2D shear flows to shed light on the dynamical mechanism underlying non-locality in dense granular flows
Probing exotic phenomena at the interface of nuclear and particle physics with the electric dipole moments of diamagnetic atoms: A unique window to hadronic and semi-leptonic CP violation
The current status of electric dipole moments of diamagnetic atoms which
involves the synergy between atomic experiments and three different theoretical
areas -- particle, nuclear and atomic is reviewed. Various models of particle
physics that predict CP violation, which is necessary for the existence of such
electric dipole moments, are presented. These include the standard model of
particle physics and various extensions of it. Effective hadron level combined
charge conjugation (C) and parity (P) symmetry violating interactions are
derived taking into consideration different ways in which a nucleon interacts
with other nucleons as well as with electrons. Nuclear structure calculations
of the CP-odd nuclear Schiff moment are discussed using the shell model and
other theoretical approaches. Results of the calculations of atomic electric
dipole moments due to the interaction of the nuclear Schiff moment with the
electrons and the P and time-reversal (T) symmetry violating
tensor-pseudotensor electron-nucleus are elucidated using different
relativistic many-body theories. The principles of the measurement of the
electric dipole moments of diamagnetic atoms are outlined. Upper limits for the
nuclear Schiff moment and tensor-pseudotensor coupling constant are obtained
combining the results of atomic experiments and relativistic many-body
theories. The coefficients for the different sources of CP violation have been
estimated at the elementary particle level for all the diamagnetic atoms of
current experimental interest and their implications for physics beyond the
standard model is discussed. Possible improvements of the current results of
the measurements as well as quantum chromodynamics, nuclear and atomic
calculations are suggested.Comment: 46 pages, 19 tables and 16 figures. A review article accepted for
EPJ
Involvement, Tate and me
The involvement construct has been explored in relation to products, services and leisure but not in an art museum context. The purpose of this paper is to address this theoretical gap by drawing on the marketing and leisure literature to understand membersâ consumption of Tate using the involvement construct. Tate, a portfolio of four art museums in the UK has more than 90,000 members that receive a benefits package in return for a membership fee. Data were collected using an interpretive, qualitative approach. 59 face to face semi-structured interviews were conducted with Tate Members during spring 2008. The narratives expose the complexity in exploring the involvement construct and the analysis revealed six new involvement characteristics: 1) Centrality and Pleasure; 2) Desire to Learn; 3) Escapism: Spirituality and Creativity; 4) Sense of Belonging and Prestige; 5) Physical; and 6) Drivers of Involvement. These are discussed in the context of previous studies into museum consumption, services and leisure involvement literature. The authors discuss how these findings may be transferred to other settings and the managerial implications for marketers and membership managers are considered