Search results for "visti"
showing 10 items of 759 documents
Medium-modified jets and initial state fluctuations as sources of charge correlations measured at energies available at the BNL Relativistic Heavy Io…
2011
We investigate the contribution of medium-modified jets and initial state fluctuations to the asymmetry in charged-particle production with respect to the reaction plane. This asymmetry has been suggested as a compelling signature for the chiral magnetic effect in QCD and makes the study of conventional scenarios for the creation of such charged-particle multiplicity fluctuations a timely endeavor. The different path-length combinations of jets through the medium in noncentral heavy ion collisions result in finite correlations of like and different charged particles emitted in the different hemispheres. Our calculation is based on the combination of jet events from Yet another Jet Energy-Lo…
Charged-pion cross sections and double-helicity asymmetries in polarizedp+pcollisions ats=200 GeV
2015
We present midrapidity charged-pion invariant cross sections, the ratio of the pi(-) to pi(+) cross sections and the charge-separated double-spin asymmetries in polarized p + p collisions at root s = p + 200 GeV. While the cross section measurements are consistent within the errors of next-to-leading-order (NLO) perturbative quantum chromodynamics predictions (pQCD), the same calculations overestimate the ratio of the charged-pion cross sections. This discrepancy arises from the cancellation of the substantial systematic errors associated with the NLO-pQCD predictions in the ratio and highlights the constraints these data will place on flavor-dependent pion fragmentation functions. The char…
The form factor of the pion in point-form of relativistic dynamics revisited
2003
The electromagnetic form factor of the pion is calculated in the "point-form" of relativistic quantum mechanics using simple, phenomenological wave functions. It is found that the squared charge radius of the pion is predicted one order of magnitude larger than the experimental value and the asymptotic behavior expected from QCD cannot be reproduced. The origin of these discrepancies is analyzed. The present results confirm previous ones obtained from a theoretical model and call for major improvements in the implementation of the "point-form" approach.
Recent results from PHENIX on the evolution of hot QCD
2014
The Relativistic Heavy Ion Collider’s (RHIC) energy scan program explores the phase transition between the hadron gas and the quark gluon plasma phases by varying center-of-mass energies from √sNN = 7.7 to 200 GeV and using various system sizes. The nuclear modification factor of π0 and the azimuthal anisotropy of charged hadrons were measured in Au+Au collisions at c.m. energies √sNN = 39, 62.4 and 200 GeV. In addition, we present recent results of direct photon yield and anisotropy measurements in Au+Au collisions at c.m. energy √sNN = 200 GeV.
Nucleon Structure Functions and Light-Front Dynamics
1999
We present a quark-parton model to describe polarized and unpolarized nucleon structure functions. The twist-two matrix elements for the QCD evolution analysis of lepton-hadron scattering are calculated within a light-front covariant quark model. The relativistic effects in the three-body wave function are discussed for both the polarized and unpolarized cases. Predictions are given for the polarized gluon distributions as will be seen in future experiments.
Search for CP-violating nuclear magnetic quadrupole moment using the LuOH+ cation
2020
The time-reversal and spatial parity violating interaction of the nuclear magnetic quadrupole moment (MQM) of the 175Lu and 176Lu nuclei with electrons in the molecular cation LuOH+ is studied. The resulting effect is expressed in terms of fundamental parameters, such as quantum chromodynamics angle θ⎯⎯, quark electric dipole moment (EDM), and chromo-EDM. For this, we have estimated the magnetic quadrupole moments of 175Lu and 176Lu nuclei and calculated the molecular constant that characterizes the interaction of the MQM with electrons in the considered molecules. Additionally, we predict the hyperfine structure constants for the ground electronic state of LuOH+. In the molecular calculati…
Faddeev study of heavy baryon spectroscopy
2007
16 pages, 3 figures.-- PACS nrs.: 12.39.Jh, 12.39.Pn, 14.20.-c.-- ISI Article Identifier: 000246249100015.-- ArXiv pre-print available at: http://arxiv.org/abs/hep-ph/0703257
Are there compact heavy four-quark bound states?
2007
6 pages, 1 figure.-- PACS nrs.: 12.39.Jh; 14.40.Lb.-- ISI Article Identifier: 000251327200050.-- ArXiv pre-print available at: http://arxiv.org/abs/0710.2516
The pion distribution amplitude and the pion-photon transition form factor in a nonlocal chiral quark model
2014
We study the pion Distribution Amplitude (\pi DA) in the context of a nonlocal chiral quark model. The corresponding Lagrangian reproduces the phenomenological values of the pion mass and decay constant, as well as the momentum dependence of the quark propagator obtained in lattice calculations. It is found that the obtained \pi DA has two symmetric maxima, which arise from the new contributions generated by the nonlocal character of the interactions. This \pi DA is applied to leading order and next-to-leading order calculations of the pion-photon transition form factor. Implications of the results are discussed.
A non-relativistic model for the $[cc][\bar{c}\bar{c}]$ tetraquark
2017
We use a non-relativistic model to study the spectroscopy of a tetraquark composed of $[cc][\bar{c}\bar{c}]$ in a diquark-antidiquark configuration. By numerically solving the Schr\"{o}dinger equation with a Cornell-inspired potential, we separate the four-body problem into three two-body problems. Spin-dependent terms (spin-spin, spin-orbit and tensor) are used to describe the splitting structure of the $c\bar{c}$ spectrum and are also extended to the interaction between diquarks. Recent experimental data on charmonium states are used to fix the parameters of the model and a satisfactory description of the spectrum is obtained. We find that the spin-dependent interaction is sizable in the …