42 research outputs found
Higgs-photon associated production at colliders
We present complete analytical expressions for the amplitudes of the process
. The calculation is performed using nonlinear
gauges, which significantly simplifies both the actual analytical calculation
and the check of its gauge invariance. After comparing our results with a
previous numerical calculation, we extend the range of Higgs masses and center
of mass energies to those appropriate to LEP 200 and a future linear collider.Comment: To appear in PRD. 18 pages latex, uses REVTEX; 5 postscript figure
Analysis of Intelligent Classifiers and Enhancing the Detection Accuracy for Intrusion Detection System
In this paper we discuss and analyze some of the intelligent classifiers
which allows for automatic detection and classification of networks attacks for
any intrusion detection system. We will proceed initially with their analysis
using the WEKA software to work with the classifiers on a well-known IDS
(Intrusion Detection Systems) dataset like NSL-KDD dataset. The NSL-KDD dataset
of network attacks was created in a military network by MIT Lincoln Labs. Then
we will discuss and experiment some of the hybrid AI (Artificial Intelligence)
classifiers that can be used for IDS, and finally we developed a Java software
with three most efficient classifiers and compared it with other options. The
outputs would show the detection accuracy and efficiency of the single and
combined classifiers used
Form Factors and QCD in Spacelike and Timelike Region
We analyze the basic hard exclusive processes: \pi\gamma*\gamma - transition,
pion and nucleon electromagnetic form factors, and discuss the analytic
continuation of QCD formulas from the spacelike q^2<0 to the timelike region
q^2 >0 of the relevant momentum transfers. We describe the construction of the
timelike version of the coupling constant \alpha_s. We show that due to the
analytic continuation of the collinear logarithms each eigenfunction of the
evolution equation acqiures a phase factor and investigate the resulting
interference effects which are shown to be very small. We found no sources for
the K-factor-type enhancements in the perturbative QCD contribution to the
hadronic form factors. To study the soft part of the pion electromagnetic form
factor, we use a QCD sum rule inspired model and show that there are
non-canceling Sudakov double logarithms which result in a K-factor-type
enhancement in the timelike region.Comment: 12 pages, LaTeX; a few typos corrected, references adde
Natural disturbance impacts on trade-offs and co-benefits of forest biodiversity and carbon
With accelerating environmental change, understanding forest disturbance impacts on trade-offs between biodiversity and carbon dynamics is of high socio-economic importance. Most studies, however, have assessed immediate or short-term effects of disturbance, while long-term impacts remain poorly understood. Using a tree-ring-based approach, we analysed the effect of 250 years of disturbances on present-day biodiversity indicators and carbon dynamics in primary forests. Disturbance legacies spanning centuries shaped contemporary forest co-benefits and trade-offs, with contrasting, local-scale effects. Disturbances enhanced carbon sequestration, reaching maximum rates within a comparatively narrow post-disturbance window (up to 50 years). Concurrently, disturbance diminished aboveground carbon storage, which gradually returned to peak levels over centuries. Temporal patterns in biodiversity potential were bimodal; the first maximum coincided with the short-term post-disturbance carbon sequestration peak, and the second occurred during periods of maximum carbon storage in complex old-growth forest. Despite fluctuating local-scale trade-offs, forest biodiversity and carbon storage remained stable across the broader study region, and our data support a positive relationship between carbon stocks and biodiversity potential. These findings underscore the interdependencies of forest processes, and highlight the necessity of large-scale conservation programmes to effectively promote both biodiversity and long-term carbon storage, particularly given the accelerating global biodiversity and climate crises
Production of neutral and charged Higgs bosons of the MSSM at the future e-gamma colliders
A complete study for the production of neutral (h^0, H^0, A^0 (= \phi^0_i))
and charged Higgs (H^\pm) bosons at electron-photon colliders is presented in
the context of the minimal supersymmetric standard model.
A particular choice of the non-linear R_\xi gauge is used to evaluate the
amplitudes of the reaction e-gamma --> e \phi^0_i.
The resulting cross section indicates that it will be possible to detect a
signal from the neutral Higgs bosons for most regions of parameter space at the
future linear colliders with \sqrt{s}=500 GeV through the reaction e gamma -->
e \phi^0_i. This reaction also offers the interesting possibility to measure
the Higgs mass through the detection of the outgoing electron.
The production of the charged Higgs boson through the reaction e gamma -->
\nu_e H^\pm$ has in general smaller values for the cross section, which seems
more difficult to observe.Comment: submitted to Phys. Rev.
Differential Requirements of Two recA Mutants for Constitutive SOS Expression in Escherichia coli K-12
Background Repairing DNA damage begins with its detection and is often followed by elicitation of a cellular response. In E. coli, RecA polymerizes on ssDNA produced after DNA damage and induces the SOS Response. The RecA-DNA filament is an allosteric effector of LexA auto-proteolysis. LexA is the repressor of the SOS Response. Not all RecA-DNA filaments, however, lead to an SOS Response. Certain recA mutants express the SOS Response (recAC) in the absence of external DNA damage in log phase cells. Methodology/Principal Findings Genetic analysis of two recAC mutants was used to determine the mechanism of constitutive SOS (SOSC) expression in a population of log phase cells using fluorescence of single cells carrying an SOS reporter system (sulAp-gfp). SOSC expression in recA4142 mutants was dependent on its initial level of transcription, recBCD, recFOR, recX, dinI, xthA and the type of medium in which the cells were grown. SOSC expression in recA730 mutants was affected by none of the mutations or conditions tested above. Conclusions/Significance It is concluded that not all recAC alleles cause SOSC expression by the same mechanism. It is hypothesized that RecA4142 is loaded on to a double-strand end of DNA and that the RecA filament is stabilized by the presence of DinI and destabilized by RecX. RecFOR regulate the activity of RecX to destabilize the RecA filament. RecA730 causes SOSC expression by binding to ssDNA in a mechanism yet to be determined