58 research outputs found

    New constraints for CP-violating forces between nucleons in the range 10-4 cm - 1 cm

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    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

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    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

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    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

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    It was pointed out recently that oscillation of the neutron nn into mirror neutron nn', 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 nnn-n' oscillation in the case when a mirror magnetic field B\vec{B}' is non-zero and show that in this case it can be suppressed or resonantly enhanced by applying the ordinary magnetic field B\vec{B}, depending on its strength and on its orientation with respect to B\vec{B}'. The recent experimental data, under this hypothesis, still allow the nnn-n' 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 3σ3\sigma 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

    Path to AWAKE : evolution of the concept

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    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]

    Bio-analytical Assay Methods used in Therapeutic Drug Monitoring of Antiretroviral Drugs-A Review

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