739 research outputs found
Constraints on Baryon-Nonconserving Yukawa Couplings in a Supersymmetric Theory
The 1-loop evolution of couplings in the minimal supersymmetric standard
model, extended to include baryon nonconserving operators through
explicit -parity violation, is considered keeping only
superpotential terms involving the maximum possible number of third generation
superfields. If all retained Yukawa couplings are required to remain in
the perturbative domain upto the scale of gauge group unification,
upper bounds ensue on the magnitudes of the coupling strengths at
the supersymmetry breaking scale, independent of the model of unification. They
turn out to be similar to the corresponding fixed point values reached from a
wide range of (including all greater than unity) at the unification
scale. The coupled evolution of the top and Yukawa couplings results
in a reduction of the fixed point value of the former.Comment: PRL-TH-94/8 and TIFR/TH/94-7, 15 pages, LaTe
Signals of neutralinos and charginos from gauge boson fusion at the CERN Large Hadron Collider
We point out that interesting signals of the non-strongly interacting sector
of the supersymmetric standard model arise from the production of charginos and
neutralinos via vector boson fusion (VBF) at the Large Hadron Collider (LHC).
In particular, if R-parity is violated, the hadronically quiet signals of
charginos and neutralinos through direct production get considerably
suppressed. We show that in such cases, the VBF channel can be useful in
identifying this sector through clean and background-free final states.Comment: 10 pages Latex, 8 figures, minor changes in text and few references
added, to be published in Phys. Rev.
Like Sign Dilepton Signature for R-Parity Violating SUSY Search at the Tevatron Collider
The like sign dileptons provide the most promising signature for
superparticle search in a large category of -parity violating SUSY models.
We estimate the like sign dilepton signals at the Tevatron collider, predicted
by these models, over a wide region of the MSSM parameter space. One expects an
unambiguous signal upto a gluino mass of GeV ( GeV) with
the present (proposed) accumulated luminosity of .Comment: 12 page LaTeX file; 5 figures available upon request from the autho
Recursive Calculation of One-Loop QCD Integral Coefficients
We present a new procedure using on-shell recursion to determine coefficients
of integral functions appearing in one-loop scattering amplitudes of gauge
theories, including QCD. With this procedure, coefficients of integrals,
including bubbles and triangles, can be determined without resorting to
integration. We give criteria for avoiding spurious singularities and boundary
terms that would invalidate the recursion. As an example where the criteria are
satisfied, we obtain all cut-constructible contributions to the one-loop
n-gluon scattering amplitude, A_n^{oneloop}(...--+++...), with split-helicity
from an N=1 chiral multiplet and from a complex scalar. Using the
supersymmetric decomposition, these are ingredients in the construction of QCD
amplitudes with the same helicities. This method requires prior knowledge of
amplitudes with sufficiently large numbers of legs as input. In many cases,
these are already known in compact forms from the unitarity method.Comment: 36 pages; v2 clarification added and typos fixed, v3 typos fixe
Aids-related plasmablastic lymphoma of the oral cavity associated with an IgH/MYC translocation–treatment with autologous stem-cell transplantation in a patient with severe haemophilia-A
Plasmablastic lymphoma is an AIDS related lymphoma that continues to have a poor prognosis despite significant advances in the management of HIV and lymphoproliferative diseases. In part this has been due to limited insights into the biology of this disease and the molecular mechanisms of oncogenesis. To date molecular abnormalities have not been described in plasmablastic lymphoma, and its aggressive clinical behaviour has been difficult to understand. We describe the first reported cytogenetic abnormality in plasmablastic lymphoma, an IgH/MYC translocation. It is also the first description of autologous stem cell transplantation in a patient with severe haemophilia A
A study of single sneutrino production in association with fermion pairs at polarised photon colliders
We investigate single sneutrino production in the context of
R-parity-violating Supersymmetry at future linear colliders. The
sneutrino is produced in association with fermion pairs and it is shown that
its decays into two further fermions will lead to a clean signal. We also
discuss possible backgrounds and the effects of beam polarisation.Comment: 31 pages, LaTeX, 10 postscript figures. Title has been modified. Two
new figures and one appendix added. Detailed SM background estimations were
made. A new reference added. Version to appear in PR
Genomic landscape and actionable mutations of brain metastases derived from non–small cell lung cancer: A systematic review
Background
Brain metastases derived from non–small cell lung cancer (NSCLC) represent a significant clinical problem. We aim to characterize the genomic landscape of brain metastases derived from NSCLC and assess clinical actionability.
Methods
We searched Embase, MEDLINE, Web of Science, and BIOSIS from inception to 18/19 May 2022. We extracted information on patient demographics, smoking status, genomic data, matched primary NSCLC, and programmed cell death ligand 1 expression.
Results
We found 72 included papers and data on 2346 patients. The most frequently mutated genes from our data were EGFR (n = 559), TP53 (n = 331), KRAS (n = 328), CDKN2A (n = 97), and STK11 (n = 72). Common missense mutations included EGFR L858R (n = 80) and KRAS G12C (n = 17). Brain metastases of ever versus never smokers had differing missense mutations in TP53 and EGFR, except for L858R and T790M in EGFR, which were seen in both subgroups. Of the top 10 frequently mutated genes that had primary NSCLC data, we found 37% of the specific mutations assessed to be discordant between the primary NSCLC and brain metastases.
Conclusions
To our knowledge, this is the first systematic review to describe the genomic landscape of brain metastases derived from NSCLC. These results provide a comprehensive outline of frequently mutated genes and missense mutations that could be clinically actionable. These data also provide evidence of differing genomic landscapes between ever versus never smokers and primary NSCLC compared to the BM. This information could have important consequences for the selection and development of targeted drugs for these patients
Higgs Boson Decay into Hadronic Jets
The remarkable agreement of electroweak data with standard model (SM)
predictions motivates the study of extensions of the SM in which the Higgs
boson is light and couples in a standard way to the weak gauge bosons.
Postulated new light particles should have small couplings to the gauge bosons.
Within this context it is natural to assume that the branching fractions of the
light SM-like Higgs boson mimic those in the standard model. This assumption
may be unwarranted, however, if there are non-standard light particles coupled
weakly to the gauge bosons but strongly to the Higgs field. In particular, the
Higgs boson may effectively decay into hadronic jets, possibly without
important bottom or charm flavor content. As an example, we present a simple
extension of the SM, in which the predominant decay of the Higgs boson occurs
into a pair of light bottom squarks that, in turn, manifest themselves as
hadronic jets. Discovery of the Higgs boson remains possible at an
electron-positron linear collider, but prospects at hadron colliders are
diminished substantially.Comment: 30 pages, 7 figure
Search for Global Dipole Enhancements in the HiRes-I Monocular Data above 10^{18.5} eV
Several proposed source models for Ultra-High Energy Cosmic Rays (UHECRs)
consist of dipole distributions oriented towards major astrophysical landmarks
such as the galactic center, M87, or Centaurus A. We use a comparison between
real data and simulated data to show that the HiRes-I monocular data for
energies above 10^{18.5} eV is, in fact, consistent with an isotropic source
model. We then explore methods to quantify our sensitivity to dipole source
models oriented towards the Galactic Center, M87, and Centaurus A.Comment: 17 pages, 31 figure
Analysis of the vector form factors and with light-cone QCD sum rules
In this article, we calculate the vector form factors and
within the framework of the light-cone QCD sum rules
approach. The numerical values of the are compatible with the
existing theoretical calculations, the central value of the ,
, is in excellent agreement with the values from the chiral
perturbation theory and lattice QCD. The values of the are
very large comparing with the theoretical calculations and experimental data,
and can not give any reliable predictions. At large momentum transfers with
, the form factors and can
either take up the asymptotic behavior of or decrease more
quickly than , more experimental data are needed to select the
ideal sum rules.Comment: 22 pages, 16 figures, revised version, to appear in Eur. Phys. J.
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