6,976 research outputs found
Measurements of Diffractive Processes at CDF
We review the results of measurements on hard diffractive processes performed
by the CDF Collaboration and report preliminary CDF results on two soft
diffractive processes with a leading antiproton and a rapidity gap in addition
to that associated with the antiproton. All results have been obtained from
data collected in Run I of the Fermilab Tevatron collider.Comment: 7 pages, Presented at 14 Topical Conference on Hadron Collider
Physics, HCP-2002, Karlsruhe, Germany, 29 Sep - 4 Oct 200
Experimental review of diffractive phenomena
A review is given of the measurements of the hard diffractive interactions in
recent years from two high-energy colliders, the HERA collider and the
Tevatron collider. The structure of the diffractive exchange in
terms of partons, the factorisation properties and the ratio of diffractive to
non-diffractive cross sections are discussed.Comment: Contribution to the proceedings of BARYONS 2004. LaTeX 10 page
Energy Level Diagrams for Black Hole Orbits
A spinning black hole with a much smaller black hole companion forms a
fundamental gravitational system, like a colossal classical analog to an atom.
In an appealing if imperfect analogy to atomic physics, this gravitational atom
can be understood through a discrete spectrum of periodic orbits. Exploiting a
correspondence between the set of periodic orbits and the set of rational
numbers, we are able to construct periodic tables of orbits and energy level
diagrams of the accessible states around black holes. We also present a closed
form expression for the rational q, thereby quantifying zoom-whirl behavior in
terms of spin, energy, and angular momentum. The black hole atom is not just a
theoretical construct, but corresponds to extant astrophysical systems
detectable by future gravitational wave observatories.Comment: 8 page
Diffractive Higgs boson production at Tevatron and LHC: an experimental review
We discuss the different models of central diffractive production of the
Higgs boson at the Tevatron and the LHC. We also describe how the models can be
tested using diffractive production data being taken at the Tevatron. We
finally discuss the advantages of using diffractive events to reconstruct the
mass of the Higgs boson especially at the LHC.Comment: short review to be published in Mod. Phys. Let
Triangular mass matrices for quarks and leptons
We assume that all quark and lepton mass matrices which appear
in the standard model lagrangian (after spontaneous symmetry breaking) with
neutrinos treated as Dirac patricles have the triangular form. Such matrices
have not only less non-zero elements (three of them are equal to zero) but also
lead to very asymmetrical decomposition into one diagonal and two unitary
matrices for quarks and leptons. We also assume that unitary matrices which
transform flavor into definite mass states for right handed components (weakly
non-interacting) in the same weak isodoublet are equal. Using all available
experimental data on quark and lepton masses and mixing angles, treating in the
universal way quarks and leptons, we determine the triangular mass matrices for
up and down type quarks, neutrinos and charged leptons and as a consequence
mixing matrices for left-handed and right handed components. As the result of
the fit we get predictions for the neutrino masses including smallest neutrino
mass. The calculations without CP violation and with inclusion of this effect
in quark sector are also presented.Comment: 12 pages, no figure
Diffraction in hadron-hadron interactions
Results on soft and hard diffraction in and collisions are
reviewed with emphasis on factorization and scaling properties of differential
cross sections. While conventional factorization breaks down at high energies,
a scaling behavior emerges, which leads to a universal description of
diffractive processes in terms of a (re)normalized rapidity gap probability
distribution.Comment: 12 pages, Late
W Boson Cross Section and Decay Properties at the Tevatron
We present the first measurements of sigma(p\bar{p} -> W -> l nu) and
sigma(p\bar{p} -> Z -> l l) at sqrt{s} = 1.96 TeV, along with new measurements
of W angular-decay distributions in p\bar{p} collisions at sqrt{s} = 1.8 TeV.Comment: Submitted to ICHEP 2002 proceeding
Design and Expected Performance of the BTeV RICH
The BTeV experiment is a b-physics experiment designed to conduct precision
tests of the CKM description of CP violation and study rare processes involving
bottom and charm hadrons. The experiment will be located in the C0 interaction
region at the Fermilab Tevatron, and is intended to begin data-taking around
2007-2008. One of the most important elements of the BTeV spectrometer is the
ring-imaging Cerenkov detector (RICH) which is used for particle
identification. In this article we describe the BTeV RICH and present its
expected performance.Comment: 5 pages, 5 figures. Proceedings of the RICH2002 Conference, Pylos,
Greece, June 5-10, 200
Top Quark Mass Measurements at CDF
Recent measurements of the mass of the top quark are presented using 162 pb-1
of data of ppbar collisions at sqrt(s)=1.96 TeV collected by the CDF detector
at the Tevatron collider during Run II. The analyses focus on the semi-leptonic
decay mode with one or two identified bottom quarks. The Template Method
reconstructs the invariant mass of the top quark in each event. The
Multivariate Template Method enhances this approach by adding information on
the event topology. The Dynamical Likelihood Method discriminates between
possible mass values using top quark decay observables and attempts to use the
maximum amount of information on top quarks provided by the Standard Model. All
three methods produce similar results. The Dynamical Likelihood Method yields a
top quark mass of 177.8+-4.5/5.0(stat)+-6.2(sys)GeV/c^2.Comment: 4 pages, 3 figures. Referee's comments included. To appear in the
proceedings of the 6th International Conference on Hyperons, Charm and Beauty
Hadrons, June 27 - July 03, 2004, Chicago, IL, US
Top squark mass: current limits revisited and new limits from Tevatron Run-I
Analyzing the -jets+ \met (where ), data from Run-I of
the Tevatron using the Bayesian technique, we obtain model independent limits
on the product \br(\lstop\ra be^{+}\nu_e \lspone) \times \br(\lstop^{*}\ra
\bar{b}q\bar{q^{\prime}}\lspone) for different values of the lighter top
squark(\lstop) mass and the lightest supersymmetric particle(\lspone) mass.
The SUSY signals have been simulated by interfacing the 4-body decay of
\lstop at the parton level with the event generator PYTHIA. These limits have
been translated into exclusion plots in the \mlstop-\mlspone plane, which
also turn out to be fairly model independent for fixed values of the BR of the
competing loop decay mode \lstop\ra c \lspone. Assuming the loop decay BR to
be negligible and using the leading order cross section for \lstoplstop pair
production, we obtain conservatively \mlstop \ge 77.0 (74.5) GeV for
\mlspone=5(15) GeV, while for \br(\lstop\ra c \lspone)=20%, the
corresponding limits are \mlstop \ge 68.0 (65.0) GeV. Using the larger next
to leading order cross-section stronger limits are obtained. For example, if
\br(\lstop\ra c \lspone)=20%, \mlstop \ge 73.0 (72.7) GeV for
\mlspone=5(15) GeV. Our limits nicely complement the ALEPH bounds which get
weaker for low \mlspone.Comment: 11 pages, 5 figures, few comments adde
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