58 research outputs found
New constraints for CP-violating forces between nucleons in the range 10-4 cm - 1 cm
The range of nucleon interaction 10-4 cm - 1 cm is interesting because it
corresponds to the mass range of a intermediate particle inside so named "axion
window" that is not closed yet by experiment. Depolarization of ultracold
neutrons (UCN) during their storage in material traps can be caused by
CP-violating pseudo-magnetic precession of the neutron spin in the vicinity of
the unpolarized substance surface. Using the experimental limits for UCN
depolarization new constraints were set for the product of the scalar,
pseudo-scalar dimensionless constants gS*gP and the parameter lam_PS,
determining the Yukawa-type of the nucleon interaction potential via new
pseudo-scalar boson (axion-like particle) with a mass of m_PS: gS*gP*lam_PS^2
<= 2.96*10-21 [cm^2] for 10-3 cm < lam_PS < 1 cm; gS*gP*lam_PS^2 <= 3.9*10-22
[cm^2] for 10-4 cm < lam_PS < 10-3 cm. Improvement of the limit for gS*gP in
the area of lam_PS from 0.1 cm to 1 cm accounts for 4-5 orders of magnitude in
comparision with previous limit. The prospects of increasing in accuracy search
for CP-violating pseudo-magnetic precession are considered. The estimations of
the possible effects of pseudo-magnetic precession in the frame of the
theoretical models with CP-violation are discussed.Comment: 8 page
A dimensionally continued Poisson summation formula
We generalize the standard Poisson summation formula for lattices so that it
operates on the level of theta series, allowing us to introduce noninteger
dimension parameters (using the dimensionally continued Fourier transform).
When combined with one of the proofs of the Jacobi imaginary transformation of
theta functions that does not use the Poisson summation formula, our proof of
this generalized Poisson summation formula also provides a new proof of the
standard Poisson summation formula for dimensions greater than 2 (with
appropriate hypotheses on the function being summed). In general, our methods
work to establish the (Voronoi) summation formulae associated with functions
satisfying (modular) transformations of the Jacobi imaginary type by means of a
density argument (as opposed to the usual Mellin transform approach). In
particular, we construct a family of generalized theta series from Jacobi theta
functions from which these summation formulae can be obtained. This family
contains several families of modular forms, but is significantly more general
than any of them. Our result also relaxes several of the hypotheses in the
standard statements of these summation formulae. The density result we prove
for Gaussians in the Schwartz space may be of independent interest.Comment: 12 pages, version accepted by JFAA, with various additions and
improvement
Lattice-switch Monte Carlo
We present a Monte Carlo method for the direct evaluation of the difference
between the free energies of two crystal structures. The method is built on a
lattice-switch transformation that maps a configuration of one structure onto a
candidate configuration of the other by `switching' one set of lattice vectors
for the other, while keeping the displacements with respect to the lattice
sites constant. The sampling of the displacement configurations is biased,
multicanonically, to favor paths leading to `gateway' arrangements for which
the Monte Carlo switch to the candidate configuration will be accepted. The
configurations of both structures can then be efficiently sampled in a single
process, and the difference between their free energies evaluated from their
measured probabilities. We explore and exploit the method in the context of
extensive studies of systems of hard spheres. We show that the efficiency of
the method is controlled by the extent to which the switch conserves correlated
microstructure. We also show how, microscopically, the procedure works: the
system finds gateway arrangements which fulfill the sampling bias
intelligently. We establish, with high precision, the differences between the
free energies of the two close packed structures (fcc and hcp) in both the
constant density and the constant pressure ensembles.Comment: 34 pages, 9 figures, RevTeX. To appear in Phys. Rev.
More about neutron - mirror neutron oscillation
It was pointed out recently that oscillation of the neutron into mirror
neutron , a sterile twin of the neutron with exactly the same mass, could
be a very fast process with the the baryon number violation, even faster than
the neutron decay itself. This process is sensitive to the magnetic fields and
it could be observed by comparing the neutron lose rates in the UCN storage
chambers for different magnetic backgrounds. We calculate the probability of
oscillation in the case when a mirror magnetic field is
non-zero and show that in this case it can be suppressed or resonantly enhanced
by applying the ordinary magnetic field , depending on its strength
and on its orientation with respect to . The recent experimental
data, under this hypothesis, still allow the oscillation time order 1 s
or even smaller. Moreover, they indicate that the neutron losses are sensitive
to the orientation of the magnetic field. %at about level. If these
hints will be confirmed in the future experiments, this would point to the
presence of the mirror magnetic field on the Earth of the order of 0.1 G, or
some equivalent spin-dependent force of the other origin that makes a
difference between the neutron and mirror neutron states.Comment: 10 page
Período de suplementação de ractopamina em dietas para suínos machos castrados em terminação
Path to AWAKE : evolution of the concept
This paper describes the conceptual steps in reaching the design of the AWAKE experiment currently under construction at CERN. We start with an introduction to plasma wakefield acceleration and the motivation for using proton drivers. We then describe the self-modulation instability - a key to an early realization of the concept. This is then followed by the historical development of the experimental design, where the critical issues that arose and their solutions are described. We conclude with the design of the experiment as it is being realized at CERN and some words on the future outlook. A summary of the AWAKE design and construction status as presented in this conference is given in Gschwendtner et al. [1]
Duração da suplementação de ractopamina em dietas para leitoas em terminação mantidas sob alta temperatura ambiente
Bio-analytical Assay Methods used in Therapeutic Drug Monitoring of Antiretroviral Drugs-A Review
Alimentação de suínos em terminação com dietas contendo ractopamina e extratos cítricos: desempenho e características de carcaça
- …