共查询到20条相似文献,搜索用时 109 毫秒
1.
H. -Th. Elze 《Zeitschrift fur Physik C Particles and Fields》1988,38(1):211-218
The gluon transport equations (Phys. Lett. 177B (1986) 402) are reconsidered to derive a consistent semiclassical limit. Introducing the color current of gluon fluctuations around a classical mean field, we calculate the color permeability function of a collisionless gluon plasma in linear response approximation. The dispersion relations and electric screening length agree with one-loop high temperature QCD results. We find no magnetic screening atO(g 2) and predict transverse magnetic plasma oscillations similar to electric ones. The extension to include particle production by a mean color field is shortly described. 相似文献
2.
I.M. Dremin 《The European Physical Journal C - Particles and Fields》2008,56(1):81-86
The equations of in-medium gluodynamics are proposed. Their classical lowest order solution is explicitly shown for a color
charge moving with constant speed. For nuclear permittivity larger than 1 it describes emission of Cherenkov gluons resembling
the results of classical electrodynamics. The choice of nuclear permittivity and Lorentz invariance of the problem are discussed.
Effects induced by the transversely and longitudinally moving (relative to the collision axis) partons at LHC energies are
described. 相似文献
3.
《Annals of Physics》1985,161(1):48-80
A classical relativistic kinetic theory for a plasma with non-Abelian gauge interactions is formulated. After the local equilibrium solutions for the quark distribution function are found, the associated moment equations and their near-equilibrium expansion, leading to a set of relativistic chromohydrodynamical equations for viscous colored fluids, are studied. 相似文献
4.
G. Abbiendi et al. 《The European Physical Journal C - Particles and Fields》1999,11(2):217-238
Gluon jets are identified in hadronic Z decays as all the particles in a hemisphere opposite to a hemisphere containing two tagged quark jets. Gluon jets defined
in this manner are equivalent to gluon jets produced from a color singlet point source and thus correspond to the definition
employed for most theoretical calculations. In a separate stage of the analysis, we select quark jets in a manner to correspond
to calculations, as the particles in hemispheres of flavor tagged light quark (uds) events. We present the distributions of
rapidity, scaled energy, the logarithm of the momentum, and transverse momentum with respect to the jet axes, for charged
particles in these gluon and quark jets. We also examine the charged particle multiplicity distributions of the jets in restricted
intervals of rapidity. For soft particles at large , we observe the charged particle multiplicity ratio of gluon to quark jets to be , in agreement with the prediction that this ratio should approximately equal the ratio of QCD color factors, . The intervals used to define soft particles and large for this result, GeV/ and GeV/, are motivated by the predictions of the Herwig Monte Carlo multihadronic event generator. Additionally, our gluon jet data
allow a sensitive test of the phenomenon of non-leading QCD terms known as color reconnection. We test the model of color
reconnection implemented in the Ariadne Monte Carlo multihadronic event generator and find it to be disfavored by our data.
Received: 24 February 1999 / Published online: 8 September 1999 相似文献
5.
M. Magg 《Physics letters. [Part B]》1978,77(2):199-202
The Coulomb solution of the classical Yang-Mills equations with external source is unstable for sufficiently strong coupling constant. We show that the Yang-Mills system has no other physically static, spherically symmetric solution. Some consequences for the quark confinement problem in non-abelian gauge theories are pointed out. 相似文献
6.
Kazem Bitaghsir Fadafan Hong Liu Krishna Rajagopal Urs Achim Wiedemann 《The European Physical Journal C - Particles and Fields》2009,61(4):553-567
We determine the energy it takes to move a test quark along a circle of radius L with angular frequency ω through the strongly coupled plasma of
supersymmetric Yang–Mills (SYM) theory. We find that for most values of L and ω the energy deposited by stirring the plasma in this way is governed either by the drag force acting on a test quark moving
through the plasma in a straight line with speed v=L
ω or by the energy radiated by a quark in circular motion in the absence of any plasma, whichever is larger. There is a continuous
crossover from the drag-dominated regime (ω≲π
T(1−v
2)3/4, meaning ω≲π
T and L small enough) to the radiation-dominated regime (ω≳π
T(1−v
2)3/4). In the crossover regime we find evidence for significant destructive interference between energy loss due to drag and due
to radiation as if in vacuum. The rotating quark thus serves as a model system in which the relative strength of, and interplay
between, two different mechanisms of parton energy loss is accessible via a controlled classical gravity calculation. We close
by speculating on the implications of our results for a quark that is moving through the plasma in a straight line while decelerating,
although in this case the classical calculation breaks down at the same value of the deceleration as the one at which the
radiation-dominated regime sets in. 相似文献
7.
8.
We investigate the dynamics of the chiral transition in an expanding quark-antiquark plasma. The calculations are made within a linear σ-model with explicit quark and antiquark degrees of freedom. We solve numerically the classical equations of motion for chiral fields coupled to the fluid dynamical equations for the plasma. Fast initial growth and strong oscillations of the chiral field and strong amplification of long wavelength modes of the pion field are observed in the course of the chiral transition. 相似文献
9.
10.
《Nuclear Physics A》2005,750(1):30-63
We discuss two special limiting forms of QCD matter which may be produced at RHIC. We conclude from the available empirical evidence that an equilibrated, but strongly coupled quark–gluon plasma has been made in such collisions. We also discuss the growing body of evidence that its source is a color glass condensate. 相似文献
11.
V. S. Filinov M. Bonitz Y. B. Ivanov V. V. Skokov P. R. Levashov V. E. Fortov 《等离子体物理论文集》2011,51(4):322-327
A strongly coupled plasma of quark and gluon quasiparticles is studied by combination of Path integral Monte Carlo and quantum Wigner dynamics simulations. This method extends previous classical nonrelativistic simu‐lations based on a color Coulomb interaction to the quantum regime. First results for the momentum‐momentum autocorrelation function and diffusion constant are presented (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
12.
The behavior of a quark in a monopole-type field is studied, the field being the solution of the equations of motion of a classical field for nonlinear effective Lagrangian in the IR region. The Dirac equation (at J = 0) in this field can be transformed to a supersymmetric form (in the energy ground state, equal to zero, which leads to the possibility of quark maintenance). The solution of the classical Wong equations in the monopole field is considered and the quantities which are conserved are determined.Translated from Izvestiya Uchebnykh Zavedenii, Fizika, No. 6, pp. 36–41, June, 1989. 相似文献
13.
I. M. Dremin 《Physics of Atomic Nuclei》2010,73(4):657-671
The equations of in-medium gluodynamics are proposed. Their classical lowest-order solution is explicitly shown for a color
charge moving with constant speed. For chromopermittivity larger than 1 it describes emission of Cherenkov gluons resembling
results of classical electrodynamics. The values of the real and imaginary parts of the chromopermittivity are obtained from
the fits to experimental data on the double-humped structure around the away-side jet obtained at RHIC. The dispersion of
the chromopermittivity is predicted by comparing the RHIC, SPS, and cosmic-ray data. This is important for LHC experiments.
Cherenkov gluons may be responsible for the asymmetry of dilepton mass spectra near ρ meson observed in the SPS experiment with excess in the low-mass wing of the resonance. This feature is predicted to be common
for all resonances. The “color rainbow” quantum effect might appear according to higher-order terms of in-medium QCD if the
chromopermittivity depends on color. 相似文献
14.
M. Döring S. Ejiri O. Kaczmarek F. Karsch E. Laermann 《The European Physical Journal C - Particles and Fields》2006,46(1):179-189
We analyze the dependence of heavy quark free energies on the baryon chemical potential μb in 2-flavor QCD by performing a 6th order Taylor expansion in the chemical potential which circumvents the sign problem.
The bare quark mass at
corresponds to a pion mass of about 770 MeV and is thus not in the range of physical quark masses but the quark mass dependence
is known to be small above Tc. At Nτ = 4 the lattices are coarse, however, we are using improved (p4 staggered) fermions. The Taylor expansion coefficients of
color singlet and color averaged free energies are calculated and from this the expansion coefficients for the corresponding
screening masses are determined. We find that for small μb the free energies of a static quark-antiquark pair decrease in a medium with a net excess of quarks and that screening is
well described by a screening mass which increases with increasing μb. The μb-dependent corrections to the screening masses are well described by perturbation theory for T ≳ 2Tc. In particular, we find for all temperatures above Tc that the expansion coefficients for singlet and color averaged screening masses differ by a factor 2.
PACS. 11.15.Ha, 11.10.Wx, 12.38Gc, 12.38.Mh 相似文献
15.
The NΔ and ΔΔ dibaryon resonances are studied by calculating the NN scattering phase shifts with explicitly coupling these dibaryon channels in a multi-channel coupling calculation with two quark models.These quark models,the chiral quark model and quark delocalization color screening model,describe the NN S-,D-wave phase shifts below the π production threshold quantitatively well.Both quark models predict the ~1D_2 resonance discovered in NN partial wave phase shift analysis and the J=1 or 3 isoscalar resonance recently reported by CELSIUS-WASA Collaboration are NΔ~5S_2 and ΔΔ~7S_3 resonance,respectively.Further measurements at COSY,LEPS and Lanzhou Cooling Storage Ring(CSR) to check the ΔΔ resonance are discussed. 相似文献
16.
17.
GAO Ying-Jia ZHANG Yu-Jie CHAO Kuang-Ta 《理论物理通讯》2006,46(6):1017-1022
We study radiative decays of T to light quark jets in nonrelativistic QCD by taking both the color singlet and color octet b^-b operators into consideration. The cut for quark jet energy and cut for the angle between two quark jets are introduced. The sensitivity to the soft and collinear singularities in the loop integrals are greatly reduced by these cuts. With the jet energy cut of about 1 GeV, and the jet angle cut of about 36°, the branching ratio for γ→ rq^- is found to be 8.2 × 10^-4 from color singlet contributions. The color octet contributions could be much larger than that of color singlet, depending on the estimate of the color octet matrix elements. This process may provide a new test for the color octet mechanism in nonrelativistic QCD. 相似文献
18.
19.
E. Abdalla R. Banerjee C. Molina 《The European Physical Journal C - Particles and Fields》2000,17(3):467-471
We compute the quark–antiquark potential in three-dimensional massive quantum electrodynamics for an arbitrary fermion mass.
The result indicates that screening prevails for any quark masses, contrary to the classical expectations, generalizing our
previous result obtained for large masses. We also test the validity of several approximation schemes using a detailed numerical
analysis. The classical result is still reproduced for a small separation of the quarks.
Received: 16 May 2000 / Published online: 25 September 2000 相似文献
20.
Static spherically symmetric space-time is studied to describe dense compact star with quark matter within the framework of MIT Bag Model. The system of Einstein’s field equations for anisotropic matter is expressed as a new system of differential equations using transformations and it is solved for a particular general form of gravitational potential with parameters. For a particular parameter, as an example, it is shown that the model satisfies all major physical features expected in a realistic star. The generated model also smoothly matches with the Schwarzschild exterior metric at the boundary of the star. It is shown that the generated solutions are useful to model strange quark stars. 相似文献