Search results for "Interaction"
showing 10 items of 5710 documents
Electroweak penguins in isospin-violating Bs decays
2011
¯Bs ! φ π 0 and ¯ Bs ! φ ρ 0 , which are dominated by EW penguins. Our results extend the analysis in [1] and have recently been published in [2]. Here we give a brief overview of the outcome. We show that in presence of a new EW penguin amplitude the two Bs branching ratios can be enhanced by an order of magnitude without violating any constraints from other hadronic B decays. This makes them very interesting modes for LHCb and Super B factories. We perform both a model-independent analysis and a study within realistic New Physics (NP) models such as a modified- Z 0 -penguin scenario, a model with an additional Z 0 boson and the MSSM, including a fit to B ! πK data and the relevant experim…
On Interchangeability of Probe-Object Roles in Quantum-Quantum Interaction-Free Measurement
2019
In this paper we examine Interaction-free measurement (IFM) where both the probe and the object are quantum particles. We argue that in this case the description of the measurement procedure must by symmetrical with respect to interchange of the roles of probe and object. A thought experiment is being suggested that helps to determine what does and what doesn't happen to the state of the particles in such a setup. It seems that unlike the case of classical object, here the state of both the probe and the object must change. A possible explanation of this might be that the probe and the object form an entangled pair as a result of non-interaction.
Non-local stiffness and damping models for shear-deformable beams
2013
This paper presents the dynamics of a non-local Timoshenko beam. The key assumption involves modeling non-local effects as long-range volume forces and moments mutually exerted by non-adjacent beam segments, that contribute to the equilibrium of any beam segment along with the classical local stress resultants. Elastic and viscous long-range volume forces/moments are endowed in the model. They are built as linearly depending on the product of the volumes of the interacting beam segments and on generalized measures of their relative motion, based on the pure deformation modes of the beam. Attenuation functions governing the space decay of the non-local effects are introduced. Numerical resul…
Constraints on four-fermion interactions from the tt¯ charge asymmetry at hadron colliders
2016
The charge asymmetry in top quark production at hadron colliders is sensitive to beyond-the-Standard-Model four-fermion interactions. In this study we compare the sensitivity of $$t\bar{t}$$ cross-section and charge asymmetry measurements to effective operators describing four-fermion interactions and study the limits on the validity of this approach. A fit to a combination of Tevatron and LHC measurements yields stringent limits on the linear combinations $$C_1$$ and $$C_2$$ of the four-fermion effective operators.
Insight Into The Spin-Vibronic Problem of a Mixed Valence Magnetic Molecular Cell for Quantum Cellular Automata.
2021
The effects of the vibronic coupling in quantum cellular automata (QCA) based on the square planar mixed valence (MV) molecular cells comprising four paramagnetic centers (spin cores) and two excess mobile electrons are analyzed in the important particular case when the Coulomb energy gap between the ground antipodal diagonal-type two-electron configurations and the excited side-type configurations considerably exceeds both the one-electron transfer parameter (strong U-limit) and the vibronic stabilization energy. Under such conditions the developed model involves the second-order double exchange, the Heisenberg-Dirac-Van Vleck (HDVV) exchange and the vibronic coupling of the excess electro…
Rotation of Molecules and Nuclear Spin Relaxation
1978
Nuclear spin relaxation has been developed as a standard method for studying molecular motions in liquids, solids, polymers, and—to a lesser extent—gases, staring with the pioneering work of Bloembergen, Purcell, and Pound [1]. Of the great variety of molecular motions possible (e.g., translations, rotations, vibrations) rotations are particularly important for nuclear spin relaxation. Conversely, nuclear spin relaxation can be especially successful if information about rotational motions is desired. In this case nuclear spin relaxation can yield quantitative information over an extraordinary wide range of characteristic frequencies, from about 1 Hz to 1014Hz. It shoud be noted that, typica…
X-ray absorption spectra at the CaL2,3edge calculated within multichannel multiple scattering theory
2004
We report a theoretical method for x-ray absorption spectroscopy (XAS) in condensed matter which is based on the multichannel multiple scattering theory of Natoli et al. and the eigen-channel $R$-matrix method. While the highly flexible real-space multiple scattering (RSMS) method guarantees a precise description of the single-electron part of the problem, multiplet-like electron correlation effects between the photoelectron and localized electrons can be taken account for in a configuration interaction scheme. For the case where correlation effects are limited to the absorber atom, a technique for the solution of the equations is devised, which requires only little more computation time th…
High-resolution study of some doubly excited vibrational states of PH2D: the m1 + m2, m2 + m5, m2 + m3, and m2 + m6 bands
2004
Abstract The absorption bands ν 1 + ν 2 , ν 2 + ν 3 , and ν 2 + ν 6 of PH 2 D have been recorded for the first time using a high-resolution Bruker 120 HR interferometer, and rotationally analyzed. Some transitions belonging to the very weak band ν 2 + ν 5 and enhanced in intensity by strong interactions with the ν 1 + ν 2 band were also assigned. Sets of parameters obtained from the fit reproduce experimental line position of the bands ν 1 + ν 2 and ν 2 + ν 3 with about the experimental accuracy. The residuals of the ro-vibrational energies of the ν 2 + ν 6 band are about 10 times larger. Reasons for the poorer reproduction of the latter data are given.
Quantum Sensors Assisted by Spontaneous Symmetry Breaking for Detecting Very Small Forces
2015
We propose a quantum-sensing scheme for measuring weak forces based on a symmetry-breaking adiabatic transition in the quantum Rabi model. We show that the system described by the Rabi Hamiltonian can serve as a sensor for extremely weak forces with sensitivity beyond the yoctonewton (yN) per sqrt (Hz) range. We propose an implementation of this sensing protocol using a single trapped ion. A major advantage of our scheme is that the force detection is performed by projective measurement of the population of the spin states at the end of the transition, instead of the far slower phonon number measurement used hitherto.
ISOLTRAP Mass Measurements for Weak-Interaction Studies
2005
International audience; The conserved-vector-current (CVC) hypothesis of the weak interaction and the unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) matrix are two fundamental postulates of the Standard Model. While existing data on CVC supports vector current conservation, the unitarity test of the CKM matrix currently fails by more than two standard deviations. High-precision mass measurements performed with the ISOLTRAP experiment at ISOLDE/CERN provide crucial input for these fundamental studies by greatly improving our knowledge of the decay energy of super-allowed beta decays. Recent results of mass measurements on the beta emitters 18Ne, 22Mg, 34Ar, and 74Rb as pertaining to weak-i…