475 research outputs found
Experimental Techniques
In this course we will give examples for experimental techniques used in
particle physics experiments. After a short introduction, we will discuss
applications in silicon microstrip detectors, wire chambers, and single photon
detection in Ring Imaging Cherenkov (RICH) counters. A short discussion of the
relevant physics processes, mainly different forms of energy loss in matter, is
enclosed.Comment: 20 pages with 15 figures included. Course given at the VII Mexican
Workshop on Particles and Fields, Merida, Yucatan, Mexico, November 10-17,
1999. Proceedings to be published by AI
SELEX RICH Performance and Physics Results
SELEX took data in the 1996/7 Fixed Target Run at Fermilab. The excellent
performance parameters of the SELEX RICH Detector had direct influence on the
quality of the obtained physics results.Comment: Contributed talk at the Fourth Workshop on RICH Detectors, June 5-10,
2002, Pylos, Greece. Accepted for publication in NIM
Semileptonic Decays of Heavy Omega Baryons in a Quark Model
The semileptonic decays of and are treated in the
framework of a constituent quark model developed in a previous paper on the
semileptonic decays of heavy baryons. Analytic results for the form
factors for the decays to ground states and a number of excited states are
evaluated. For to the form factors obtained are shown to
satisfy the relations predicted at leading order in the heavy-quark effective
theory at the non-recoil point. A modified fit of nonrelativistic and
semirelativistic Hamiltonians generates configuration-mixed baryon wave
functions from the known masses and the measured \lcle rate, with wave
functions expanded in both harmonic oscillator and Sturmian bases. Decay rates
of \ob to pairs of ground and excited \omc states related by heavy-quark
symmetry calculated using these configuration-mixed wave functions are in the
ratios expected from heavy-quark effective theory, to a good approximation. Our
predictions for the semileptonic elastic branching fraction of vary
minimally within the models we use. We obtain an average value of (84 2%)
for the fraction of decays to ground states, and 91%
for the fraction of decays to the ground state
. The elastic fraction of \ob \to \omc ranges from about 50%
calculated with the two harmonic-oscillator models, to about 67% calculated
with the two Sturmian models.Comment: 52 pages, 8 figure
Isospin splittings of doubly heavy baryons
The SELEX Collaboration has reported a very large isospin splitting of doubly
charmed baryons. We show that this effect would imply that the doubly charmed
baryons are very compact. One intriguing possibility is that such baryons have
a linear geometry Q-q-Q where the light quark q oscillates between the two
heavy quarks Q, analogous to a linear molecule such as carbon dioxide. However,
using conventional arguments, the size of a heavy-light hadron is expected to
be around 0.5 fm, much larger than the size needed to explain the observed
large isospin splitting. Assuming the distance between two heavy quarks is much
smaller than that between the light quark and a heavy one, the doubly heavy
baryons are related to the heavy mesons via heavy quark-diquark symmetry. Based
on this symmetry, we predict the isospin splittings for doubly heavy baryons
including Xi_{cc}, Xi_{bb} and Xi_{bc}. The prediction for the Xi_{cc} is much
smaller than the SELEX value. On the other hand, the Xi_{bb} baryons are
predicted to have an isospin splitting as large as (6.3\pm1.7) MeV. An
experimental study of doubly bottomed baryons is therefore very important to
better understand the structure of baryons with heavy quarks.Comment: 11 page
Renaissance of the ~1 TeV Fixed-Target Program
This document describes the physics potential of a new fixed-target program
based on a ~1 TeV proton source. Two proton sources are potentially available
in the future: the existing Tevatron at Fermilab, which can provide 800 GeV
protons for fixed-target physics, and a possible upgrade to the SPS at CERN,
called SPS+, which would produce 1 TeV protons on target. In this paper we use
an example Tevatron fixed-target program to illustrate the high discovery
potential possible in the charm and neutrino sectors. We highlight examples
which are either unique to the program or difficult to accomplish at other
venues.Comment: 31 pages, 11 figure
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