747 research outputs found
Theoretical overview on tau physics
Precise measurements of the tau lepton properties provide stringent tests of
the Standard Model structure and accurate determinations of its parameters. We
overview the present status of a few selected topics: lepton universality, QCD
tests and the determination of alpha_s, m_s and V_us from hadronic tau decays,
and lepton flavor violation phenomena.Comment: Invited talk at the International Workshop on Tau-Charm Physics
(Charm2006), Beijing, China, June 5-7, 2006. 8 pages, 2 figure
Alternating commensurate-incommensurate structures in the magnetic phase diagram of CsNiF3
The magnetic phase diagram of the quasi one-dimensional spinchain system
CsNiF below the N\'eel temperature is determined. For magnetic fields
perpendicular to the spin chains incommensurate phases are predicted. From
linear spin-wave theory we obtain the instability line of the paramagnetic
phase as a function of the strength and the direction of the field. The system
undergoes a transition to a commensurate or an incommensurate phase depending
on the direction of the magnetic field. In the commensurate phase the
characterizing wave vector is locked to values describing a two-sublattice
structure, whereas in the incommensurate phase the wave vector changes
continuously between the corresponding two-sublattice wave vectors.Comment: 11 pages, LaTeX, 5 figures, sent to PRB Rapid Communicatio
Effect of long range connections on an infinite randomness fixed point associated with the quantum phase transitions in a transverse Ising model
We study the effect of long-range connections on the infinite-randomness
fixed point associated with the quantum phase transitions in a transverse Ising
model (TIM). The TIM resides on a long-range connected lattice where any two
sites at a distance r are connected with a non-random ferromagnetic bond with a
probability that falls algebraically with the distance between the sites as
1/r^{d+\sigma}. The interplay of the fluctuations due to dilutions together
with the quantum fluctuations due to the transverse field leads to an
interesting critical behaviour. The exponents at the critical fixed point
(which is an infinite randomness fixed point (IRFP)) are related to the
classical "long-range" percolation exponents. The most interesting observation
is that the gap exponent \psi is exactly obtained for all values of \sigma and
d. Exponents depend on the range parameter \sigma and show a crossover to
short-range values when \sigma >= 2 -\eta_{SR} where \eta_{SR} is the anomalous
dimension for the conventional percolation problem. Long-range connections are
also found to tune the strength of the Griffiths phase.Comment: 5 pages, 1 figure, To appear in Phys. Rev.
The effect of magnetic dipolar interactions on the interchain spin wave dispersion in CsNiF_3
Inelastic neutron scattering measurements were performed on the ferromagnetic
chain system CsNiF_3 in the collinear antiferromagnetic ordered state below T_N
= 2.67K. The measured spin wave dispersion was found to be in good agreement
with linear spin wave theory including dipolar interactions. The additional
dipole tensor in the Hamiltonian was essential to explain some striking
phenomena in the measured spin wave spectrum: a peculiar feature of the
dispersion relation is a jump at the zone center, caused by strong dipolar
interactions in this system. The interchain exchange coupling constant and the
planar anisotropy energy were determined within the present model to be J'/k_B
= -0.0247(12)K and A/k_B = 3.3(1)K. This gives a ratio J/J' \approx 500, using
the previously determined intrachain coupling constant J/k_B = 11.8$. The small
exchange energy J' is of the same order as the dipolar energy, which implies a
strong competition between the both interactions.Comment: 18 pages, TeX type, 7 Postscript figures included. To be published in
Phys. Rev.
Перспективы развития трубопроводной системы на Дальнем Востоке
We report synthesis of colloids with polymer core and inorganic shell consisting of silver nanoparticles (AgNPs) which can be used as building blocks for the preparation of conducting composite films. Polymer colloids based on copolymer of styrene and butyl acrylate with variable film formation temperature and functional surface have been prepared by surfactant-free emulsion polymerization. Polymer particles with average size between 140 nm and 220 nm and narrow size distribution were used as templates for deposition of AgNPs by microwave-assisted reduction of silver precursors in aqueous medium. The loading of the AgNPs on the polymer particle surface has been increased up to 60 wt.-%. Obtained hybrid colloids were used for preparation of composite films. The electrical conductivity of the composite films starts to increase if the AgNPs loading on the polymer particle surface is above 20 wt.-%
Radiative and non radiative muon capture on the proton in heavy baryon chiral perturbation theory
We have evaluated the amplitude for muon capture by a proton, mu + p --> n +
nu, to O(p^3) within the context of heavy baryon chiral perturbation theory
(HBChPT) using the new O(p^3) Lagrangian of Ecker and Mojzis (E&M). We obtain
expressions for the standard muon capture form factors and determine three of
the coefficients of the E&M Lagrangian, namely, b_7, b_{19}, and b_{23}. We
describe progress on the next step, a calculation of the radiative muon capture
process, mu + p --> n + nu + gamma.Comment: Talk at the 15th Int. Conf. on Few-Body Problems in Physics, 22-26
July, 1997, Groningen, The Netherlands, to be published in the proceedings; 5
pages, LaTeX, using espcrc1.st
Hard Corrections as a Probe of the Symmetry Breaking Sector
Non-decoupling effects related to a large affecting non-oblique
radiative corrections in vertices () and boxes (- mixing
and ) are very sensitive to the particular mechanism of spontaneous
symmetry breaking. We analyze these corrections in the framework of a chiral
electroweak standard model and find that there is only one operator in the
effective lagrangian which modifies the longitudinal part of the boson
without touching the oblique corrections. The inclusion of this operator
affects the vertex, the - mixing and the CP-violating
parameter , generating interesting correlations among the hard
corrections to these observables, for example, the maximum
vertex correction allowed by low energy physics is about one
percent.Comment: LaTex, 8 pages, 1 postscript figure include
Anomalous Chiral Behavior in Quenched Lattice QCD
A study of the chiral behavior of pseudoscalar masses and decay constants is
carried out in quenched lattice QCD with Wilson fermions. Using the modified
quenched approximation (MQA) to cure the exceptional configuration problem,
accurate results are obtained for pion masses as low as 200 MeV. The
anomalous chiral log effect associated with quenched loops is studied
in both the relation between vs. and in the light-mass
behavior of the pseudoscalar and axial vector matrix elements. The size of
these effects agrees quantitatively with a direct measurement of the
hairpin graph, as well as with a measurement of the topological susceptibility,
thus providing several independent and quantitatively consistent determinations
of the quenched chiral log parameter . For with
clover-improved fermions all results are consistent with
.Comment: 51 pages, 20 figures, Late
Measurement of the electric dipole moment using longitudinal polarization of beams
Certain CP-odd momentum correlations in the production and subsequent decay
of pairs in collisions are enhanced significantly when the
and beams are longitudinally polarized. These may be used to probe
the real and imaginary parts of , the electric dipole moment of
the . Closed-form expressions for these ``vector correlations'' and the
standard deviation of the operators defining them due to standard model
interactions are presented for the two-body final states of decays. If
42\% average polarization of each beam is achieved, as proposed for the
tau-charm factories, with equal integrated luminosities for each sign of
polarization and a total yield of pairs, it is
possible to attain sensitivities for of , , cm respectively and for of , , cm respectively at the three operating center-of-mass energies of
3.67, 4.25 and 10.58 GeV. These bounds emerge when the effects of a posible
weak dipole form factor are negligible as is the case when it is of
the same order of magnitude as . Furthermore, in such a
polarization experiment where different polarizations are possible, a
model-independent disentangling of their individual effects is possible, and a
technique to achieve this is described. A strong longitudinal polarization
physics programme at the tau-charm factory appears warranted.Comment: 30 pages, latex, no figure
Political brand identity: an examination of the complexities of Conservative brand and internal market engagement during the 2010 UK General Election campaign
This paper seeks to build an understanding of the importance of internal communications when building a strong political brand. Using Kapferer’s brand prism as a conceptual framework, the paper explores UK Conservative Party members’ attitudes towards the development of the Conservative brand as personified by David Cameron. There are clear implications for political strategists as the findings suggest that it is crucial to engage the internal market in the co-creation of the marketing communications strategy for as brand evangelists they interpret the brand promise at the local level
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