701 research outputs found
Signatures of HyperCharge Axions in Colliders
If in addition to the standard model fields, a new pseudoscalar field that
couples to hypercharge topological number density, the hypercharge axion,
exists, it can be produced in colliders in association with photons or Z
bosons, and detected by looking for its decay into photons or Z's. For a range
of masses below a TeV and coupling above a fraction of 1/TeV, existing data
from LEP II and the Tevatron can already put interesting constraints, and in
future colliders accessible detection range is increased significantly. The
hypercharge axion can help in explaining the matter-antimatter asymmetry in the
universe.Comment: 11 pages, 8 figures, uses axodraw.st
The Longitudinal Polarimeter at HERA
The design, construction and operation of a Compton back-scattering laser
polarimeter at the HERA storage ring at DESY are described. The device measures
the longitudinal polarization of the electron beam between the spin rotators at
the HERMES experiment with a fractional systematic uncertainty of 1.6%. A
measurement of the beam polarization to an absolute statistical precision of
0.01 requires typically one minute when the device is operated in the
multi-photon mode. The polarimeter also measures the polarization of each
individual electron bunch to an absolute statistical precision of 0.06 in
approximately five minutes. It was found that colliding and non-colliding
bunches can have substantially different polarizations. This information is
important to the collider experiments H1 and ZEUS for their future
longitudinally polarized electron program because those experiments use the
colliding bunches only.Comment: 21 pages (Latex), 14 figures (EPS
Integration of a smoking cessation program in the treatment protocol for patients with head and neck and lung cancer
Smoking is the main causative factor for development of head and neck and lung cancer. In addition, other malignancies such as bladder, stomach, colorectal, kidney and pancreatic cancer have a causative relation with smoking. Continued smoking after having been diagnosed with cancer has many negative consequences: effectiveness of radiotherapy is diminished, survival time is shortened and risks of recurrence, second primary malignancies and treatment complications are increased. In view of the significant health consequences of continued smoking, therefore, additional support for patients to stop smoking seems a logical extension of the present treatment protocols for smoking-related cancers. For prospectively examining the effect of nursing-delivered smoking cessation programme for patients with head and neck or lung cancer, 145 patients with head and neck or lung cancer enrolled into this programme over a 2-year period. Information on smoking behaviour, using a structured, programme specific questionnaire, was collected at baseline, and after 6 and 12Â months. At 6Â months, 58 patients (40%) had stopped smoking and at 12Â months, 48 patients (33%) still had refrained from smoking. There were no differences in smoking cessation results between patients with head and neck and lung cancer. The only significant factor predicting success was whether the patient had made earlier attempts to quit smoking. A nurse-managed smoking cessation programme for patients with head and neck or lung cancer shows favourable long-term success rates. It seems logical, therefore, to integrate such a programme in treatment protocols for smoking-related cancers
On Radiative Weak Annihilation Decays
We discuss a little-studied class of weak decay modes sensitive to only one
quark topology at leading order in G_F: M --> m gamma, where M,m are mesons
with completely distinct flavor quantum numbers. Specifically, they proceed via
the annihilation of the valence quarks through a W and the emission of a single
hard photon, and thus provide a clear separation between CKM and strong
interaction physics. We survey relevant calculations performed to date, discuss
experimental discovery potential, and indicate interesting future directions.Comment: 10 pages LaTeX, includes macros file and 9 .eps figures. Invited talk
at RADCOR 2000 (5th Int. Symp. on Radiative Corrections), Carmel, CA, Sept.
200
A No-Lose Theorem for Higgs Searches at a Future Linear Collider
Assuming perturbativity up to a high energy scale GeV, we
demonstrate that a future linear collider operating at
500 GeV with 500 fb per year (such as the recently
proposed TESLA facility) will detect a Higgs boson signal regardless of the
complexity of the Higgs sector and of how the Higgs bosons decay.Comment: 4 pages, LaTe
Sensitivity of CPT Tests with Neutral Mesons
The sensitivity of experiments with neutral mesons to possible indirect CPT
violation is examined. It is shown that experiments conventionally regarded as
equivalent can have CPT reaches differing by orders of magnitude within the
framework of a minimal CPT- and Lorentz-violating extension of the standard
model.Comment: 4 pages REVTeX, published in Physical Review Letter
Reshuffling the OPE: Delocalized Operator Expansion
A generalization of the operator product expansion for Euclidean correlators
of gauge invariant QCD currents is presented. Each contribution to the modified
expansion, which is based on a delocalized multipole expansion of a
perturbatively determined coefficient function, sums up an infinite series of
local operators. On a more formal level the delocalized operator expansion
corresponds to an optimal choice of basis sets in the dual spaces which are
associated with the interplay of perturbative and nonperturbative N-point
correlations in a distorted vacuum. A consequence of the delocalized expansion
is the running of condensates with the external momentum. Phenomenological
evidence is gathered that the gluon condensate, often being the leading
nonperturbative parameter in the OPE, is indeed a function of resolution.
Within a model calculation of the nonperturbative corrections to the ground
state energy of a heavy quarkonium system it is shown exemplarily that the
convergence properties are better than those of the OPE. Potential applications
of the delocalized operator expansion in view of estimates of the violation of
local quark-hadron duality are discussed.Comment: Talk given at conference Continuous advances in QCD 2002 /
Arkadyfest, Minneapolis; 16 pages, 4 figure
Discovering a Light Higgs Boson with Light
We evaluate the prospects for detecting a non-standard light Higgs boson with
a significant branching ratio to two photons, in Run II of the Fermilab
Tevatron. We derive the reach for several channels: inclusive,
jet and jets. We present the expected Run II limits on
the branching ratio of as a function of the Higgs mass, for
the case of ``bosonic'', as well as ``topcolor'' Higgs bosons.Comment: 11 pages, LaTeX, 7 figures, 4 tables, uses aipproc2.sty, contributed
to the Physics at Run II Workshop, analysis redone with optimized cuts and
improved background estimate, references adde
Charmed quark component of the photon wave function
We determine the c-anti-c component of the photon wave function on the basis
of (i) the data on the transitions e+ e- -> J/psi(3096), psi(3686), psi(4040),
psi(4415), (ii) partial widths of the two-photon decays eta_{c0}(2979),
chi_{c0}(3415), chi_{c2}(3556) -> gamma-gamma, and (iii) wave functions of the
charmonium states obtained by solving the Bethe-Salpeter equation for the
c-anti-c system. Using the obtained c-anti-c component of the photon wave
function we calculate the gamma-gamma decay partial widths for radial
excitation 2S state, eta_{c0}(3594) -> gamma-gamma, and 2P states
chi_{c0}(3849), chi_{c2}(3950) -> gamma-gamma.Comment: 20 pages, 8 figure
Cosmological Constraint on the String Dilaton in Gauge-mediated Supersymmetry Breaking Theories
The dilaton field in string theories (if exists) is expected to have a mass
of the order of the gravitino mass which is in a range of
keV--1GeV in gauge-mediated supersymmetry breaking models. If it is
the case, the cosmic energy density of coherent dilaton oscillation easily
exceeds the critical density of the present universe. We show that even if this
problem is solved by a late-time entropy production (thermal inflation) a
stringent constraint on the energy density of the dilaton oscillation is
derived from experimental upperbounds on the cosmic X()-ray
backgrounds. This excludes an interesting mass region, , in gauge-mediated supersymmetry breaking models.Comment: 13 pages (RevTex file including one figure, use psfig), revised
version to be published in Physical Review Letter
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