96,590 research outputs found
Inclusion of Z->b b-bar vertex corrections in Precision Electroweak Tests on the Sp(6)_L X U(1)_Y Model
We extend our previous work on the precision electroweak tests in the Sp(6)_L
X U(1)_Y family model to include for the first time the important Z->b b-bar
vertex corrections encoded in a new variable epsilon_b, utilizing all the
latest LEP data. We include in our analysis the one loop EW radiative
corrections due to the new bosons in terms of epsilon_1, epsilon_b and
. We find that the correlation between epsilon_1 and epsilon_b
makes the combined constraint much stronger than the individual ones. The model
is consistent with the recent CDF result of m_t=174\pm 10^{+13}_{-12}\GeV,
but it can not accomodate m_t\gsim 195\GeV.Comment: Latex, 16 pages+4 figures(not included but available as uuencoded or
PS files from [email protected]), PURD-TH-94-08, SNUTP-94-4
Precision Electroweak Tests on the Model
We perform precision electroweak tests on the model.
The purpose of the analysis is to delineate the model parameters such as the
mixing angles of the extra gauge bosons present in this model. We find that the
model is already constrained considerably by the present LEP data.Comment: 14 pages+2 figures(not included), PURD-TH-93-13, to appear in Phys.
Rev. D(figures available upon request by regular mail
Density Expansion for the Mobility in a Quantum Lorentz Model
We consider the mobility of electrons in an environment of static hard-sphere
scatterers, which provides a realistic description of electrons in Helium gas.
A systematic expansion in the scatterer density is carried to second order
relative to the Boltzmann result, and the analytic contribution at this order
is derived, together with the known logarithmic term in the density expansion.
It is shown that existing experimental data are consistent with the existence
of the logarithmic term in the density expansion, but more precise experiments
are needed in order to unambiguously detect it. We show that our calculations
provide the necessary theoretical information for such an experiment, and give
a detailed discussion of a suitable parameter range.Comment: 17pp., REVTeX, 7 figure attached as 8 postscript files, db/94/
The Solar pp and hep Processes in Effective Field Theory
The strategy of modern effective field theory is exploited to pin down
accurately the flux factors for the and processes in the Sun.
The technique used is to combine the high accuracy established in few-nucleon
systems of the "standard nuclear physics approach" (SNPA) and the systematic
power counting of chiral perturbation theory (ChPT) into a consistent effective
field theory framework. Using highly accurate wave functions obtained in the
SNPA and working to \nlo3 in the chiral counting for the current, we make
totally parameter-free and error-controlled predictions for the and
processes in the Sun.Comment: 5 pages, aipproc macros are included. Talk given at International
Nuclear Physics Conference 2001, Berkeley, California, July 30 - August 3,
200
How to look for supersymmetry under the lamppost at the LHC
We apply a model-independent, agnostic approach to the collider phenomenology
of supersymmetry (SUSY), in which all mass parameters are taken as free inputs
at the weak scale. We consider the gauginos, higgsinos, and the first two
generations of sleptons and squarks, and analyze all possible mass hierarchies
among them ( in total) in which the lightest superpartner
is neutral, leading to missing energy. In each case, we identify the full set
of the dominant (i.e. least suppressed by phase space, small mixing angles or
Yukawa couplings) decay chains originating from the lightest colored
superpartner. Our exhaustive search reveals several quite dramatic yet
unexplored multilepton signatures with up to 8 isolated leptons (plus possibly
up to 2 massive gauge or Higgs bosons) in the final state. Such events are
spectacular, background-free for all practical purposes, and may lead to a
discovery of SUSY in the very early stage () of LHC
operations at 7 TeV.Comment: 4 pages, 4 figure
Erratum: Dynamics and scaling in a quantum spin chain material with bond randomness
Follow-up neutron measurements, performed on a sample much larger than the
one used in the original study, show that in the energy range 0.5-45 meV the
magnetic excitations in BaCu2SiGeO7 are indistinguishable from those in
conventional (disorder-free) quantum S=1/2 chains. Scrutinizing the previous
data, we found that the analysis was affected by a poorly identified structured
background and an additional technical mistake in the data reduction.Comment: This is a complete withdrawal of the original paper, also published
as in Phys. Rev. Lett 93, 077206 (2004). One page, one figur
Anisotropy of in-plane magnetization due to nodal gap structure in the vortex state
We examine the interplay between anisotropy of the in-plane magnetization and
the nodal gap structure on the basis of the approximate analytic solution in
the quasiclassical formalism. We show that a four-fold oscillation appears in
the magnetization, and its amplitude changes sign at an intermediate field. The
high-field oscillation originates from the anisotropy of the upper critical
field, while the low-field behavior can be understood by the thermally
activated quasiparticles near nodes depending on the applied field angles. The
temperature dependence of the magnetization also shows a similar sign change.
The anisotropy of the magnetization offers a possible measurement to identify
the gap structure directly for a wide class of type II superconductors.Comment: 4 pages, 4 figure
- …