585 research outputs found

### 略论《共产党宣言》中的马克思主义自由观

本文着眼于《共产党宣言》中若干与马克思主义自由观有关的论述,从马克思主义自由观的历史发展,信仰自由、宗教自由、政治自由等精神领域的自由、无产阶级争取自由的斗争,以及社会自由与个人自由的发展的关系等角度进行了一些探讨,并简要分析了个人自由的发展与社会自由的发展之间的关系的现实意义

### Transverse mass and invariant mass observables for measuring the mass of a semi-invisibly decaying heavy particle

Formulae are derived for the positions of end-points in the invariant mass
and transverse mass distributions obtained from the products of heavy states
decaying to pairs of semi-invisibly decaying lighter states. Formulae are
derived both for the special case where the two decay chains are identical and
the more general case where they are different. The formulae are tested with a
simple case study of heavy SUSY higgs particles decaying to gauginos at the
LHC.Comment: 13 pages, 8 eps figure

### The Analysis of Multijet Events Produced at High Energy Hadron Colliders

We define and discuss a set of (4N - 4) parameters that can be used to
analyse events in which N jets have been produced in high energy hadron-hadron
collisions. These multijet variables are the multijet mass and (4N - 5)
independent dimensionless parameters. To illustrate the use of the variables
QCD predictions are presented for events with up to five jets produced at the
Fermilab Tevatron Proton-Antiproton Collider. These QCD predictions are
compared with the predictions of a model in which multijet events uniformly
populate the N-body phase-space

### Sqrt{shat}_{min} resurrected

We discuss the use of the variable sqrt{shat}_{min}, which has been proposed
in order to measure the hard scale of a multi parton final state event using
inclusive quantities only, on a SUSY data sample for a 14 TeV LHC. In its
original version, where this variable was proposed on calorimeter level, the
direct correlation to the hard scattering scale does not survive when effects
from soft physics are taken into account. We here show that when using
reconstructed objects instead of calorimeter energy and momenta as input, we
manage to actually recover this correlation for the parameter point considered
here. We furthermore discuss the effect of including W + jets and t tbar+jets
background in our analysis and the use of sqrt{shat}_{min} for the suppression
of SM induced background in new physics searches.Comment: 23 pages, 9 figures; v2: 1 figure, several subsections and references
as well as new author affiliation added. Corresponds to published versio

### Elastic pp Scattering at LHC Energies

We consider the first LHC data for elastic pp scattering in the framework of
Regge theory with multiple Pomeron exchanges. The simplest eikonal approach
allows one to describe differential elastic cross sections at LHC, as well as
pp and $\bar{p}p$ scattering at lower collider energies, on a reasonable level.Comment: 11 pages, 5 figures, and 1 tabl

### Proton-nucleus cross section at high energies

Cross sections for proton inelastic collision with different nuclei are
described within the Glauber and multiple scattering approximations. A
significant difference between approximate `Glauber' formula and exact
calculations with a geometrical scaling assumption for very high-energy cross
section is shown. Experimental values of proton-proton cross sections obtained
using extensive air shower data are based on the relationship of proton-proton
and respective proton-air absorption cross sections. According to obtained
results values reported by the Akeno and Fly's Eye experimental groups are
about 10% overestimated. The proper energy dependence of absorption cross
section for collisions with air nuclei is of a great importance for studies of
high energy cosmic rays using the Monte Carlo technique.Comment: 9pp (9 eps figures

### How to Make Large Domains of Disoriented Chiral Condensate

Rajagopal and Wilczek have proposed that relativistic nuclear collisions can
generate domains in which the chiral condensate is disoriented. If sufficiently
large ({\it i.e.} nucleus sized), such domains can yield measurable
fluctuations in the number of neutral and charged pions. However, by numerical
simulation of the zero-temperature two-flavor linear sigma model, we find that
domains are essentially {\it pion} sized. Nevertheless, we show that large
domains can occur if the effective mesons masses are much lighter.Comment: 6 pages and 2 postscript figures, BNL-GGP-

### Effect of friction on disoriented chiral condensate formation

We have investigated the effect of friction on the DCC domain formation. We
solve the Newton equation of motion for the O(4) fields, with quenched initial
condition. The initial fields are randomly distributed in a Gaussian form. In
one dimensional expansion, on the average, large DCC domains can not be formed.
However, in some particular orbits, large instabilities may occur. This
possibility also greatly diminishes with the introduction of friction. But, if
the friction is large, the system may be overdamped and then, there is a
possibility of large DCC domain formation in some events.Comment: 9 pages, including figure

### Hadronic Total Cross-sections Through Soft Gluon Summation in Impact Parameter Space

The Bloch-Nordsieck model for the parton distribution of hadrons in impact
parameter space, constructed using soft gluon summation, is investigated in
detail.
Its dependence upon the infrared structure of the strong coupling constant
$\alpha_s$ is discussed, both for finite as well as singular, but integrable,
$\alpha_s$. The formalism is applied to the prediction of total proton-proton
and proton-antiproton cross-sections, where screening, due to soft gluon
emission from the initial valence quarks, becomes evident.Comment: 20 pages, Latex2e, input FEYNMAN,12 postscipt figures. Submitted to
PR

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