1,424 research outputs found
Partons and Jets at the LHC
I review some issues related to short distance QCD and its relation to the
experimental program of the Large Hadron Collider (LHC) now under construction
in Geneva.Comment: Talk at the conference QCD2002 at IIT Kanpur, India, November 2002.
Ten pages with 12 figure
Liquid-liquid coexistence in the phase diagram of a fluid confined in fractal porous materials
Multicanonical ensemble sampling simulations have been performed to calculate
the phase diagram of a Lennard-Jones fluid embedded in a fractal random matrix
generated through diffusion limited cluster aggregation. The study of the
system at increasing size and constant porosity shows that the results are
independent from the matrix realization but not from the size effects. A
gas-liquid transition shifted with respect to bulk is found. On growing the
size of the system on the high density side of the gas-liquid coexistence curve
it appears a second coexistence region between two liquid phases. These two
phases are characterized by a different behaviour of the local density inside
the interconnected porous structure at the same temperature and chemical
potential.Comment: 5 pages, 4 figures. To be published in Europhys. Letter
Spin operator and spin states in Galilean covariant Fermi field theories
Spin degrees of freedom of the Galilean covariant Dirac field in (4+1)
dimensions and its nonrelativistic counterpart in (3+1) dimensions are
examined. Two standard choices of spin operator, the Galilean covariant and
Dirac spin operators, are considered. It is shown that the Dirac spin of the
Galilean covariant Dirac field in (4+1) dimensions is not conserved, and the
role of non-Galilean boosts in its nonconservation is stressed out. After
reduction to (3+1) dimensions the Dirac field turns into a nonrelativistic
Fermi field with a conserved Dirac spin. A generalized form of the Levy-Leblond
equations for the Fermi field is given. One-particle spin states are
constructed. A particle-antiparticle system is discussed.Comment: Minor corrections in the text; journal versio
Color transparency in deeply inelastic diffraction
We suggest a simple physical picture for the diffractive parton distributions
that appear in diffractive deeply inelastic scattering. In this picture,
partons impinging on the proton can have any transverse separation, but only
when the separation is small can they penetrate the proton without breaking it
up. By comparing the predictions from this picture with the diffractive data
from HERA, we determine rough values for the small separations that dominate
the diffraction process.Comment: 10 pages, 2 figures; v2: citations added, two comments revised and
expanded, results unchange
Heavy Quark Production and PDF's Subgroup Report
We present a status report of a variety of projects related to heavy quark
production and parton distributions for the Tevatron Run II.Comment: Latex. 8 pages, 7 eps figures. Contribution to the Physics at Run II
Workshops: QCD and Weak Boson Physic
Cervicitis as a Clinical Indicator of Gonococcal and Chlamydial Infections in Pregnancy
Objective: We undertook the present study to attempt to apply clinical indicators predictive of cervical infection in nongravid populations with either Neisseria gonorrhoeae or Chlamydia trachomatis to our pregnant population and to determine the significance of the clinical diagnosis of “cervicitis.
Asymptotic Freedom and Bound States in Hamiltonian Dynamics
We study a model of asymptotically free theories with bound states using the
similarity renormalization group for hamiltonians. We find that the
renormalized effective hamiltonians can be approximated in a large range of
widths by introducing similarity factors and the running coupling constant.
This approximation loses accuracy for the small widths on the order of the
bound state energy and it is improved by using the expansion in powers of the
running coupling constant. The coupling constant for small widths is order 1.
The small width effective hamiltonian is projected on a small subset of the
effective basis states. The resulting small matrix is diagonalized and the
exact bound state energy is obtained with accuracy of the order of 10% using
the first three terms in the expansion. We briefly describe options for
improving the accuracy.Comment: plain latex file, 15 pages, 6 latex figures 1 page each, 1 tabl
Intrinsic transverse momentum and the polarized Drell-Yan process
In this paper we study the cross section at leading order in for
polarized Drell-Yan scattering at measured lepton-pair transverse momentum
. We find that for a hadron with spin the quark content at leading
order is described by six distribution functions for each flavor, which depend
on both the lightcone momentum fraction , and the quark transverse momentum
\bbox{k}_T^2. These functions are illustrated for a free-quark ensemble. The
cross sections for both longitudinal and transverse polarizations are expressed
in terms of convolution integrals over the distribution functions.Comment: 25 pages, REVTEX 3.0 (3 figures included in separate LATEX file using
feynman.tex), NIKHEF-94-P1 (Revised version
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