The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform

Joseph A Morrone - One of the best experts on this subject based on the ideXlab platform.

  • Momentum Distribution vibrational dynamics and the potential of mean force in ice
    Physical Review B, 2011
    Co-Authors: Joseph A Morrone, Michele Parrinello
    Abstract:

    By analyzing the Momentum Distribution obtained from path integral and phonon calculations we find that the protons in hexagonal ice experience an anisotropic quasiharmonic effective potential with three distinct principal frequencies that reflect molecular orientation. Due to the importance of anisotropy, anharmonic features of the environment cannot be extracted from existing experimental Distributions that involve the spherical average. The full directional Distribution is required, and we give a theoretical prediction for this quantity that could be verified in future experiments. Within the quasiharmonic context, anharmonicity in the ground-state dynamics of the proton is substantial and has quantal origin, a finding that impacts the interpretation of several spectroscopies.

  • displaced path integral formulation for the Momentum Distribution of quantum particles
    Physical Review Letters, 2010
    Co-Authors: Joseph A Morrone, Michele Parrinello
    Abstract:

    : The proton Momentum Distribution, accessible by deep inelastic neutron scattering, is a very sensitive probe of the potential of mean force experienced by the protons in hydrogen-bonded systems. In this work we introduce a novel estimator for the end-to-end Distribution of the Feynman paths, i.e., the Fourier transform of the Momentum Distribution. In this formulation, free particle and environmental contributions factorize. Moreover, the environmental contribution has a natural analogy to a free energy surface in statistical mechanics, facilitating the interpretation of experiments. The new formulation is not only conceptually but also computationally advantageous. We illustrate the method with applications to an empirical water model, ab initio ice, and one dimensional model systems.

  • proton Momentum Distribution in water an open path integral molecular dynamics study
    Journal of Chemical Physics, 2007
    Co-Authors: Joseph A Morrone, Varadharajan Srinivasan, Daniel Sebastiani
    Abstract:

    Recent neutron Compton scattering experiments have detected the proton Momentum Distribution in water. The theoretical calculation of this property can be carried out via “open” path integral expressions. In this work, present an extension of the staging path integral molecular dynamics method, which is then employed to calculate the proton Momentum Distributions of water in the solid, liquid, and supercritical phases. We utilize a flexible, single point charge empirical force field to model the system’s interactions. The calculated Momentum Distributions depict both agreement and discrepancies with experiment. The differences may be explained by the deviation of the force field from the true interactions. These Distributions provide an abundance of information about the environment and interactions surrounding the proton.

B S Acharya - One of the best experts on this subject based on the ideXlab platform.

  • measurement of the transverse Momentum Distribution of w bosons in pp collisions at s 7 tev with the atlas detector
    Physical Review D, 2012
    Co-Authors: B Abbott, J Abdallah, A A Abdelalim, A Abdesselam, O Abdinov, M Abolins, H Abramowicz, H Abreu, E Acerbi, B S Acharya
    Abstract:

    This paper describes a measurement of the W boson transverse Momentum Distribution using ATLAS pp collision data from the 2010 run of the LHC at root s = 7 TeV, corresponding to an integrated lumin ...

  • measurement of the normalized z γ μ μ transverse Momentum Distribution in pp collisions at s 1 96 tev
    Physics Letters B, 2010
    Co-Authors: V M Abazov, B Abbott, M Abolins, B S Acharya, M R Adams, T Adams, G D Alexeev, G Alkhazov, A Alton, G Alverson
    Abstract:

    Abstract We present a new measurement of the Z / γ ∗ transverse Momentum Distribution in the range 0–330 GeV, in proton–antiproton collisions at s = 1.96 TeV . The measurement uses 0.97 fb−1 of integrated luminosity recorded by the D0 experiment and is the first using the Z / γ ∗ → μ + μ − + X channel at this center-of-mass energy. This is also the first measurement of the Z / γ ∗ transverse Momentum Distribution that presents the result at the level of particles entering the detector, minimizing dependence on theoretical models. As any Momentum of the Z / γ ∗ in the plane transverse to the incoming beams must be balanced by some recoiling system, primarily the result of QCD radiation in the initial state, this variable is an excellent probe of the underlying process. Tests of the predictions of QCD calculations and current event generators show they have varied success in describing the data. Using this measurement as an input to theoretical predictions will allow for a better description of hadron collider data and hence it will increase experimental sensitivity to rare signals.

B Abbott - One of the best experts on this subject based on the ideXlab platform.

  • measurement of the transverse Momentum Distribution of w bosons in pp collisions at s 7 tev with the atlas detector
    Physical Review D, 2012
    Co-Authors: B Abbott, J Abdallah, A A Abdelalim, A Abdesselam, O Abdinov, M Abolins, H Abramowicz, H Abreu, E Acerbi, B S Acharya
    Abstract:

    This paper describes a measurement of the W boson transverse Momentum Distribution using ATLAS pp collision data from the 2010 run of the LHC at root s = 7 TeV, corresponding to an integrated lumin ...

  • measurement of the normalized z γ μ μ transverse Momentum Distribution in pp collisions at s 1 96 tev
    Physics Letters B, 2010
    Co-Authors: V M Abazov, B Abbott, M Abolins, B S Acharya, M R Adams, T Adams, G D Alexeev, G Alkhazov, A Alton, G Alverson
    Abstract:

    Abstract We present a new measurement of the Z / γ ∗ transverse Momentum Distribution in the range 0–330 GeV, in proton–antiproton collisions at s = 1.96 TeV . The measurement uses 0.97 fb−1 of integrated luminosity recorded by the D0 experiment and is the first using the Z / γ ∗ → μ + μ − + X channel at this center-of-mass energy. This is also the first measurement of the Z / γ ∗ transverse Momentum Distribution that presents the result at the level of particles entering the detector, minimizing dependence on theoretical models. As any Momentum of the Z / γ ∗ in the plane transverse to the incoming beams must be balanced by some recoiling system, primarily the result of QCD radiation in the initial state, this variable is an excellent probe of the underlying process. Tests of the predictions of QCD calculations and current event generators show they have varied success in describing the data. Using this measurement as an input to theoretical predictions will allow for a better description of hadron collider data and hence it will increase experimental sensitivity to rare signals.

Timo A Lahde - One of the best experts on this subject based on the ideXlab platform.

  • Momentum Distribution and contact of the unitary fermi gas
    Physical Review Letters, 2011
    Co-Authors: Joaquin E Drut, Timo A Lahde
    Abstract:

    : We calculate the Momentum Distribution n(k) of the unitary Fermi gas by using quantum Monte Carlo calculations at finite temperature T/ϵ(F) as well as in the ground state. At large momenta k/k(F), we find that n(k) falls off as C/k⁴, in agreement with the Tan relations. From the asymptotics of n(k), we determine the contact C as a function of T/ϵ(F) and present a comparison with theory. At low T/ϵ(F), we find that C increases with temperature, and we tentatively identify a maximum around T/ϵ(F) ≃ 0.4. Our calculations are performed on lattices of spatial extent up to N(x) = 14 with a particle number per unit volume of ≃ 0.03-0.07.

George Reiter - One of the best experts on this subject based on the ideXlab platform.

  • proton Momentum Distribution of liquid water from room temperature to the supercritical phase
    Physical Review Letters, 2008
    Co-Authors: C Pantalei, J. Mayers, A Pietropaolo, R Senesi, Silvia Imberti, C Andreani, Christian J Burnham, George Reiter
    Abstract:

    Measurements of the proton Momentum Distribution n(p) in water from ambient conditions to above the supercritical point are compared with theoretical calculations based on a recently developed polarizable water model. The n(p) along the H-bond direction is narrower in the dense phases, and approaches that of the isolated molecule in the more dilute phases. The theoretical model, which includes only electrostatic interactions, is unable to explain the softening of the local potential experienced by the proton in the dense phases, but it accurately predicts the n(p) for the dilute phases.

  • on the origin of the redshift of the oh stretch in ice ih evidence from the Momentum Distribution of the protons and the infrared spectral density
    Physical Chemistry Chemical Physics, 2006
    Co-Authors: C J Burnham, J. Mayers, George Reiter, T Abdulredah, H Reichert, H Dosch
    Abstract:

    Recent measurements of the Momentum Distribution in water and ice have shown that the proton is in a considerably softer potential in ice Ih than in water or the free monomer. This is broadly consistent with the large red shift observed in the vibrational spectrum. We show that existing water models, which treat the intramolecular potential as unchanged by the hydrogen bonding are unable to reproduce the Momentum Distribution. In addition, even if they can substantially explain the red shift they are unable to explain the large increase in intensity observed in the infrared spectrum in going from the monomer to ice Ih. We show that the inclusion of a bond dipole derivative term is essential to explain the observed intensities in the infrared spectrum. Though this term is partially responsible for the softening of the effective potential of the proton we show that best agreement with the observed Momentum Distribution requires a further softening of the harmonic component of the intramolecular potential. We introduce an efficient normal-mode molecular dynamics algorithm for calculating the Momentum Distribution with path-integrals.

  • Momentum Distribution Spectroscopy Using Deep Inelastic Neutron Scattering
    arXiv: Condensed Matter, 1999
    Co-Authors: George Reiter, J. Mayers, J. Noreland
    Abstract:

    We show that deep inelastic neutron scattering from hydrogen(or other light nuclei) can be used to measure a spectrum of anharmonic contributions to the target atom Momentum Distribution with high and known accuracy . The method is applied here to determine the Momentum Distribution of the hydrogen in the hydrogen bonded system KHC2O4(potassium binoxalate), where 13 anharmonic coefficients are obtained at the 2-sigma to 3-sigma level. The Momentum Distribution is obtained to an accuracy of better than few percent at all significant values of Momentum.