Search results for "Center of mass"
showing 5 items of 85 documents
Measurement of the ratios of the Z/γ∗+⩾n jet production cross sections to the total inclusive Z/γ∗ cross section in pp¯ collisions at s=1.96 TeV
2008
We present a study of events with Z bosons and jets produced at the Fermilab Tevatron Collider in ppbar collisions at a center of mass energy of 1.96 TeV. The data sample consists of nearly 14,000 Z/G* -> e+e- candidates corresponding to the integrated luminosity of 340 pb-1 collected using the D0 detector. Ratios of the Z/G* + >= n jet cross sections to the total inclusive Z/G* cross section have been measured for n = 1 to 4 jet events. Our measurements are found to be in good agreement with a next-to-leading order QCD calculation and with a tree-level QCD prediction with parton shower simulation and hadronization.
Search for Standard Model Higgs Boson Production in Association with a W Boson at CDF
2012
We present a search for the standard model Higgs boson production in association with a W boson in proton-antiproton collisions (pp̅ →W±H→ℓνbb̅ ) at a center of mass energy of 1.96 TeV. The search employs data collected with the CDF II detector which correspond to an integrated luminosity of approximately 2.7 fb-1. We recorded this data with two kinds of triggers. The first kind required high-pT charged leptons and the second required both missing transverse energy and jets. The search selects events consistent with a signature of a single lepton (e±/μ±), missing transverse energy, and two jets. Jets corresponding to bottom quarks are identified with a secondary vertex tagging method and a…
Test of the heavy quark-light diquark approximation for baryons with a heavy quark
2008
We check a commonly used approximation in which a baryon with a heavy quark is described as a heavy quark-light diquark system. The heavy quark influences the diquark internal motion reducing the average distance between the two light quarks. Besides, we show how the average distance between the heavy quark and any of the light quarks, and that between the heavy quark and the center of mass of the light diquark, are smaller than the distance between the two light quarks, which seems to contradict the heavy quark-light diquark picture. This latter result is in agreement with expectations from QCD sum rules and lattice QCD calculations. Our results also show that the diquark approximations pr…
Anomalous diffusion in polymer melts
2002
Abstract We present a study of the anomalous diffusion regimes in polymer melt dynamics performing a Monte Carlo (MC) simulation of the bond-fluctuation lattice model. Special emphasis is laid on the crossover from a Rouse-like motion to the behavior predicted by reptation theory. For the longest chains of N=400 the high statistical accuracy of the data allows for clear identification of the subdiffusive regimes in the center of mass motion and the monomer displacement. They are well compatible with those predicted by reptation theory. Furthermore a detailed analysis of the different short time anomalous diffusion regimes in the melt dynamics of polymer chains is presented and it is shown t…
Directional Control Mechanisms in Multidirectional Step Initiating Tasks.
2020
Typical anticipatory postural adjustments (APAs) in forward gait or step initiation tasks to prepare for possible disturbances caused by prime voluntary movements and to accelerate the body forward have been previously reported. However, it is not clear how wide the variations in step directions are differentiated and controlled in non-forward step initiation tasks during the APA phase. The main goal of this study is to explain the directional control mechanisms by investigating the APA of step initiation tasks in forward, diagonal, lateral, and posterior directions. The center of pressure (COP) trajectories and related muscle (soleus, tibialis anterior, and gluteus medius of both lower lim…