Search results for "Nucleon"
showing 10 items of 1041 documents
Band-terminating states in 101Ag
2004
Excited states of the neutron deficient Ag-101 nucleus have been investigated via the Cr-50(Ni-58, 3rho1alpha) heavy-ion induced reaction at 261 meV by use of in-beam spectroscopic methods. On the basis of the measured gammagamma-cincidence relations and angular distribution ratios high-spin bands have been extended up to I-pi = 35/2(+), 45/2((-)) and (49/2(-)). The negative parity states at the highest energy have been interpreted as terminating non-collective oblate states in the framework of the Nilsson-Strutinsky cranking formalism.
Electromagnetic form factors and axial charge of the nucleon from Nf = 2 + 1 Wilson fermions
2018
We present an update on our determination of the electromagnetic form factors and axial charge of the nucleon from theNf= 2 + 1 CLS ensembles with increased statistics and an additional finer lattice spacing. We also investigate the impact ofO(a)-improvement of the currents.
Probing Chiral Symmetry of Nucleons by Threshold Production
2001
Double meson production of eta and pi mesons in the threshold region is investigated in order to determine chiral properties of the nucleon. The eta can be used as a probe for the negative parity nucleon N ∗ ≡ N ∗ (1535), produced in the intermediate state. The coupling of the low energy pion in the final state is then used to extract the sign of the Yukawa coupling, gπN∗N ∗ , which distinguishes the two realizations of chiral symmetry, naive and mirror, for the nucleon.
A dispersion relation for the pion-mass dependence of hadron properties
2010
We present a dispersion relation in the pion-mass squared, which static quantities (nucleon mass, magnetic moment, etc.) obey under the assumption of analyticity in the entire complex $m_\pi^2$ plane modulo a cut at negative $m_\pi^2$ associated with pion production. The relation is verified here in a number of examples of nucleon and $\Delta$-isobar properties computed in chiral perturbation theory up to order $p^3$. We outline a method to obtain relations for other mass-dependencies, and illustrate it on a two-loop example.
Finite volume corrections to forward Compton scattering off the nucleon
2021
We calculate the spin-averaged amplitude for doubly virtual forward Compton scattering off nucleons in the framework of manifestly Lorentz invariant baryon chiral perturbation theory at complete one-loop order $O(p^4)$. The calculations are carried out both in the infinite and in a finite volume. The obtained results allow for a detailed estimation the finite-volume corrections to the amplitude which can be extracted on the lattice using the background field technique.
Spin-dependent sum rules connecting real and virtual Compton scattering verified
2017
We present a detailed derivation of the two sum rules relating the spin polarizabilities measured in real, virtual, and doubly-virtual Compton scattering. For example, the polarizability $\delta_{LT}$, accessed in inclusive electron scattering, is related to the spin polarizability $\gamma_{E1E1}$ and the slope of generalized polarizabilities $P^{(M1,M1)1}-P^{(L1,L1)1}$, measured in, respectively, the real and the virtual Compton scattering. We verify these sum rules in different variants of chiral perturbation theory, discuss their empirical verification for the proton, and prospect their use in studies of the nucleon spin structure.
Three-nucleon forces and the three-nucleon systems
1993
The basic principles and philosophy which have guided the area of few-nucleon physics are motivated and discussed. Recent advances have made it possible to solve accurately the Schrodinger (or Faddeev) equation for many of the configurations of the few-nucleon systems, A brief review is given of some of the results of these calculations, which also Indicate that one-pion exchange plays roughly the same role in binding these systems that it plays in electromagnetic meson-exchange currents. Finally, a qualitative discussion of chiral perturbation theory is presented, which highlights the role that chiral symmetry plays in the nuclear force. Three-body forces from different areas of physics ar…
Nucleon Pairing and Seniority
2007
Until now we have been dealing with particle and hole aspects of nuclear structure. In this second part of the book we go farther away from a closed major shell. Still near the beginning or end of a major shell we encounter vibrational, spherical open-shell nuclei that cannot be described in terms of a few particles or holes. Farther towards the middle of the shell the spherical shape will give way to permanent deformation signalled by rotational bands analogous to those of diatomic molecules. Microscopic description of such nuclei requires a deformed mean field as the starting point. Deformed nuclei will not be considered in any detail in this book.
Thermal conduction by dark matter with velocity and momentum-dependent cross-sections
2014
We use the formalism of Gould and Raffelt to compute the dimensionless thermal conduction coefficients for scattering of dark matter particles with standard model nucleons via cross-sections that depend on the relative velocity or momentum exchanged between particles. Motivated by models invoked to reconcile various recent results in direct detection, we explicitly compute the conduction coefficients $\alpha$ and $\kappa$ for cross-sections that go as $v_{\rm rel}^2$, $v_{\rm rel}^4$, $v_{\rm rel}^{-2}$, $q^2$, $q^4$ and $q^{-2}$, where $v_{\rm rel}$ is the relative DM-nucleus velocity and $q$ is the momentum transferred in the collision. We find that a $v_{\rm rel}^{-2}$ dependence can sig…
Dark Matter Results from 100 Live Days of XENON100 Data
2011
We present results from the direct search for dark matter with the XENON100 detector, installed underground at the Laboratori Nazionali del Gran Sasso of INFN, Italy. XENON100 is a two-phase time projection chamber with a 62 kg liquid xenon target. Interaction vertex reconstruction in three dimensions with millimeter precision allows to select only the innermost 48 kg as ultra-low background fiducial target. In 100.9 live days of data, acquired between January and June 2010, no evidence for dark matter is found. Three candidate events were observed in a pre-defined signal region with an expected background of 1.8 +/- 0.6 events. This leads to the most stringent limit on dark matter interact…