906 research outputs found
Precision Measurement of the Position-space Wave Functions of Gravitationally Bound Ultracold Neutrons
Gravity is the most familiar force at our natural length scale. However, it
is still exotic from the view point of particle physics. The first experimental
study of quantum effects under gravity was performed using a cold neutron beam
in 1975. Following this, an investigation of gravitationally bound quantum
states using ultracold neutrons was started in 2002. This quantum bound system
is now well understood, and one can use it as a tunable tool to probe gravity.
In this paper, we review a recent measurement of position-space wave functions
of such gravitationally bound states, and discuss issues related to this
analysis, such as neutron loss models in a thin neutron guide, the formulation
of phase space quantum mechanics, and UCN position sensitive detectors. The
quantum modulation of neutron bound states measured in this experiment shows
good agreement with the prediction from quantum mechanics.Comment: 13 pages, 5 figure
Proposal for measuring the quantum states of neutrons in the gravitational field with a CCD-based pixel sensor
An experimental setup is proposed for the precise measurement of the quantum
states of ultracold neutrons bound in the earth's gravitational field. The
experiment utilizes a CCD-based pixel sensor and magnification system to
observe the fine structure of the neutron distribution. In this work, we
analyzed the sensor's deposited energy measurement capability and found that
its spatial resolution was 5.3 um. A magnifying power of two orders of
magnitude was realized by using a cylindrical rod as a convex mirror.Comment: Accepted for publication in NIMA; 13 pages, 8 figure
Experimental Search for Non-Newtonian Forces in the Nanometer Scale with Slow Neutrons
Improved limits for new gravity-like short-range interactions, in which a
scattering potential is modeled by the Yukawa-type parametrization, have been
obtained by measuring the angular distribution of 6 \AA\ neutrons scattering
from atomic xenon gas. We have collected approximately
small-angle neutron scattering events. The data are interpreted as no evidence
of new forces and show improved upper limits on the coupling strength in the
interaction range of nm to nm. These improved constraints are also
interpreted as new limits for a model, in which a charge of the new forces is
expressed as a linear combination of the baryon number and the lepton number.Comment: 8 pages, 2 figures, 14TH ASIA-PACIFIC PHYSICS CONFERENCE (APPC2019
Measurement of the strong coupling alpha_S from the three-jet rate in e+e- - annihilation using JADE data
We present a measurement of the strong coupling alpha_S using the three-jet
rate measured with the Durham algorithm in e+e- -annihilation using data of the
JADE experiment at centre-of-mass energies between 14 and 44 GeV. Recent
theoretical improvements provide predictions of the three-jet rate in e+e-
-annihilation at next-to-next-to-leading order. In this paper a measurement of
the three-jet rate is used to determine the strong coupling alpha_s from a
comparison to next-to-next-to-leading order predictions matched with
next-to-leading logarithmic approximations and yields a value for the strong
coupling alpha_S(MZ) = 0.1199+- 0.0010 (stat.) +- 0.0021 (exp.) +- 0.0054
(had.) +- 0.0007 (theo.) consistent with the world average.Comment: 27 pages, 8 figure
Charged and Pseudoscalar Higgs production at a Muon Collider
We consider single charged Higgs () and pseudoscalar Higgs ()
production in association with a gauge boson at colliders. We find
that the tree-level t-channel and s-channel contributions to are enhanced for large values of , allowing
sizeable cross-sections whose analogies at colliders would be very
small. These processes provide attractive new ways of producing such particles
at colliders and are superior to the conventional methods in
regions of parameter space.Comment: 11 pages Latex, 5 figures, formulae added in sections 2.2 and 2.3,
extra discussion in section 2.3, references adde
QCD Corrections to t anti-b H^- Associated Production in e^+ e^- Annihilation
We calculate the QCD corrections to the cross section of e^+ e^- -> t anti-b
H^- and its charge-conjugate counterpart within the minimal supersymmetric
extension of the Standard Model. This process is particularly important if m_t
b H^+ and e^+ e^- -> H^+ H^- are
not allowed kinematically. Large logarithmic corrections that arise in the
on-mass-shell scheme of quark mass renormalization, especially from the t
anti-b H^- Yukawa coupling for large values of tan(beta), are resummed by
adopting the modified minimal-subtraction scheme, so that the convergence
behavior of the perturbative expansion is improved. The inclusion of the QCD
corrections leads to a significant reduction of the theoretical uncertainties
due to scheme and scale dependences.Comment: 21 pages (Latex), 8 figures (Postscript); detailed discussion of
scheme and scale dependences adde
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