Search results for "GRAVITATION"

Measurement of quantum states of neutrons in the Earth's gravitational field

2003

The lowest stationary quantum state of neutrons in the Earth's gravitational field is identified in the measurement of neutron transmission between a horizontal mirror on the bottom and an absorber/scatterer on top. Such an assembly is not transparent for neutrons if the absorber height is smaller than the ``height'' of the lowest quantum state.

Nonlocal energy density functionals for pairing and beyond-mean-field calculations

2017

We propose to use two-body regularized finite-range pseudopotential to generate nuclear energy density functional (EDF) in both particle-hole and particle-particle channels, which makes it free from self-interaction and self-pairing, and also free from singularities when used beyond mean field. We derive a sequence of pseudopotentials regularized up to next-to-leading order (NLO) and next-to-next-to-leading order (N2LO), which fairly well describe infinite-nuclear-matter properties and finite open-shell paired and/or deformed nuclei. Since pure two-body pseudopotentials cannot generate sufficiently large effective mass, the obtained solutions constitute a preliminary step towards future imp…

Probing neutrino masses with CMB lensing extraction

2005

We evaluate the ability of future cosmic microwave background (CMB) experiments to measure the power spectrum of large scale structure using quadratic estimators of the weak lensing deflection field. We calculate the sensitivity of upcoming CMB experiments such as BICEP, QUaD, BRAIN, ClOVER and PLANCK to the non-zero total neutrino mass M_nu indicated by current neutrino oscillation data. We find that these experiments greatly benefit from lensing extraction techniques, improving their one-sigma sensitivity to M_nu by a factor of order four. The combination of data from PLANCK and the SAMPAN mini-satellite project would lead to sigma(M_nu) = 0.1 eV, while a value as small as sigma(M_nu) = 0…

Kaluza-Klein FIMP dark matter in warped extra-dimensions

2020

We study for the first time the case in which Dark Matter (DM) is made of Feebly Interacting Massive Particles (FIMP) interacting just gravitationally with the standard model particles in an extra-dimensional Randall-Sundrum scenario. We assume that both the dark matter and the standard model are localized in the IR-brane and only interact via gravitational mediators, namely the graviton, the Kaluza-Klein gravitons and the radion. We found that in the early Universe DM could be generated via two main processes: the direct freeze-in and the sequential freeze-in. The regions where the observed DM relic abundance is produced are largely compatible with cosmological and collider bounds.

Gravity-mediated dark matter in clockwork/linear dilaton extra-dimensions

2020

We study for the first time the possibility that Dark Matter (represented by particles with spin $0,1/2$ or $1$) interacts gravitationally with Standard Model particles in an extra-dimensional Clockwork/Linear Dilaton model. We assume that both, the Dark Matter and the Standard Model, are localized in the IR-brane and only interact via gravitational mediators, namely the Kaluza-Klein (KK) graviton and the radion/KK-dilaton modes. We analyse in detail the Dark Matter annihilation channel into Standard Model particles and into two on-shell Kaluza-Klein towers (either two KK-gravitons, or two radion/KK-dilatons, or one of each), finding that it is possible to obtain the observed relic abundanc…

Constraint on the coupling of axionlike particles to matter via ultracold neutron gravitational experiment

2006

We present a new constraint for the axion monopole-dipole coupling in the range of 1 micrometer to a few millimeters, previously unavailable for experimental study. The constraint was obtained using our recent results on the observation of neutron quantum states in the Earth's gravitational field. We exploit the ultimate sensitivity of ultra-cold neutrons (UCN) in the lowest gravitational states above a material surface to any additional interaction between the UCN and the matter, if the characteristic interaction range is within the mentioned domain. In particular, we find that the upper limit for the axion monopole-dipole coupling constant is (g_p g_s)/(\hbar c)<2 x 10^{-15} for the ax…

Gravitational depolarization of ultracold neutrons : comparison with data

2015

We compare the expected effects of so-called gravitationally enhanced depolarization of ultracold neutrons to measurements carried out in a spin-precession chamber exposed to a variety of vertical magnetic-field gradients. In particular, we have investigated the dependence upon these field gradients of spin depolarization rates and also of shifts in the measured neutron Larmor precession frequency. We find excellent qualitative agreement, with gravitationally enhanced depolarization accounting for several previously unexplained features in the data.

Blowing up Feynman integrals

2008

In this talk we discuss sector decomposition. This is a method to disentangle overlapping singularities through a sequence of blow-ups. We report on an open-source implementation of this algorithm to compute numerically the Laurent expansion of divergent multi-loop integrals. We also show how this method can be used to prove a theorem which relates the coefficients of the Laurent series of dimensionally regulated multi-loop integrals to periods.

Erratum: Measurement of the absolute branching fractions forDs−→ℓ−ν¯ℓand extraction of the decay constantfDs[Phys. Rev. D82, 091103(R) (2010)]

2015

A method of magnetic storage of ultra-cold neutrons for a precise measurement of the neutron lifetime

1999

The beta-decay lifetime of the free neutron has been determined most precisely using storage of ultra-cold neutrons (UCNs) in material bottles. The quantity measured is the storage time which is substantially smaller than due to spurious losses of UCNs at collisions with the bottle walls. The systematic uncertainty of the correction - to the true lifetime is presently the main obstacle towards higher precision in this measurement. In the alternative magnetic trapping of UCNs, storage conditions can be realized where this correction becomes vanishingly small. This paper gives a method to measure the neutron lifetime with very low systematic errors, using confinement of UCNs in vacuum by magn…