3,475 research outputs found
Probing the Messenger of SUSY Breaking with Gaugino Masses
Gaugino masses might provide useful information on the underlying scheme of
supersymmetry breaking as they are least dependent on the unknown physics
between the TeV scale and the high messenger scale of supersymmetry breaking.
We discuss the pattern of low energy gaugino masses in various schemes of
supersymmetry breaking together with the possibility to determine the gaugino
masses at LHC.Comment: 11 pages, To appear at the Proceedings of International Workshop on
Theoretical High Energy Physics, March 2007, Roorkee, Indi
Mass measurement in boosted decay systems at hadron colliders
We report a new possibility of using the \mct2 (Constransverse mass)
variable for mass measurement in single step decay chains involving missing
particles with moderate transverse momentum. We show that its experimental
feasibility is enhanced compared to the corresponding \mt2-kink method. We
apply this method to reconstruct a pair of chargino decay chains.Comment: 6 pages, 12 figures, published in PRD,
http://link.aps.org/doi/10.1103/PhysRevD.84.03501
Gluino Stransverse Mass
We introduce a new observable, 'gluino stransverse mass', which is an
application of the Cambridge variable to the process where gluinos are
pair produced in proton-proton collision and each gluino subsequently decays
into two quarks and one LSP, $i.e. \tilde{g}\tilde{g} \to qq\tilde\chi_1^0\
qq\tilde\chi_1^0$. We show that the gluino stransverse mass can be utilized to
measure the gluino and the lightest neutralino masses separately, and also the
(1st and 2nd generation) squark masses if lighter than the gluino mass, thereby
providing a good first look at the pattern of sparticle masses experimentally.Comment: Typos corrected, Some discussions and one reference adde
M_T2-assisted on-shell reconstruction of missing momenta and its application to spin measurement at the LHC
We propose a scheme to assign a 4-momentum to each WIMP in new physics event
producing a pair of mother particles each of which decays to an invisible
weakly interacting massive particle (WIMP) plus some visible particle(s). The
transverse components are given by the value that determines the event variable
M_T2, while the longitudinal component is determined by the on-shell condition
on the mother particle. Although it does not give the true WIMP momentum in
general, this M_T2-assisted on-shell reconstruction of missing momenta provides
kinematic variables well correlated to the true WIMP momentum, and thus can be
useful for an experimental determination of new particle properties. We apply
this scheme to some processes to measure the mother particle spin, and find
that spin determination is possible even without a good knowledge of the new
particle masses.Comment: 11 pages, 10 figures, typos are corrected, figures are replace
Probing resonance decays to two visible and multiple invisible particles
We consider the decay of a generic resonance to two visible particles and any
number of invisible particles. We show that the shape of the invariant mass
distribution of the two visible particles is sensitive to both the mass
spectrum of the new particles, as well as the decay topology. We provide the
analytical formulas describing the invariant mass shapes for the nine simplest
topologies (with up to two invisible particles in the final state). Any such
distribution can be simply categorized by its endpoint, peak location and
curvature, which are typically sufficient to discriminate among the competing
topologies. In each case, we list the effective mass parameters which can be
measured by experiment. In certain cases, the invariant mass shape is
sufficient to completely determine the new particle mass spectrum, including
the overall mass scale.Comment: Added new figures, conclusions unchanged, published versio
Nitrogen doping of carbon nanoelectrodes for enhanced control of DNA translocation dynamics
Controlling the dynamics of DNA translocation is a central issue in the
emerging nanopore-based DNA sequencing. To address the potential of heteroatom
doping of carbon nanostructures to achieve this goal, herein we carry out
atomistic molecular dynamics simulations for single-stranded DNAs translocating
between two pristine or doped carbon nanotube (CNT) electrodes. Specifically,
we consider the substitutional nitrogen doping of capped CNT (capCNT)
electrodes and perform two types of molecular dynamics simulations for the
entrapped and translocating single-stranded DNAs. We find that the
substitutional nitrogen doping of capCNTs stabilizes the edge-on nucleobase
configurations rather than the original face-on ones and slows down the DNA
translocation speed by establishing hydrogen bonds between the N dopant atoms
and nucleobases. Due to the enhanced interactions between DNAs and N-doped
capCNTs, the duration time of nucleobases within the nanogap was extended by up
to ~ 290 % and the fluctuation of the nucleobases was reduced by up to ~ 70 %.
Given the possibility to be combined with extrinsic light or gate voltage
modulation methods, the current work demonstrates that the substitutional
nitrogen doping is a promising direction for the control of DNA translocation
dynamics through a nanopore or nanogap based of carbon nanomaterials.Comment: 11 pages, 4 figure
Divergent roles of the regulatory subunits of class IA PI3K
The regulatory subunit of phosphatidylinositol 3-kinase (PI3K), known as p85, is a critical component in the insulin signaling pathway. Extensive research has shed light on the diverse roles played by the two isoforms of p85, namely p85α and p85β. The gene pik3r1 encodes p85α and its variants, p55α and p50α, while pik3r2 encodes p85β. These isoforms exhibit various activities depending on tissue types, nutrient availability, and cellular stoichiometry. Whole-body or liver-specific deletion of pik3r1 have shown to display increased insulin sensitivity and improved glucose homeostasis; however, skeletal muscle-specific deletion of p85α does not exhibit any significant effects on glucose homeostasis. On the other hand, whole-body deletion of pik3r2 shows improved insulin sensitivity with no significant impact on glucose tolerance. Meanwhile, liver-specific double knockout of pik3r1 and pik3r2 leads to reduced insulin sensitivity and glucose tolerance. In the context of obesity, upregulation of hepatic p85α or p85β has been shown to improve glucose homeostasis. However, hepatic overexpression of p85α in the absence of p50α and p55α results in increased insulin resistance in obese mice. p85α and p85β have distinctive roles in cancer development. p85α acts as a tumor suppressor, but p85β promotes tumor progression. In the immune system, p85α facilitates B cell development, while p85β regulates T cell differentiation and maturation. This review provides a comprehensive overview of the distinct functions attributed to p85α and p85β, highlighting their significance in various physiological processes, including insulin signaling, cancer development, and immune system regulation
Improving the sensitivity of stop searches with on-shell constrained invariant mass variables
The search for light stops is of paramount importance, both in general as a
promising path to the discovery of beyond the standard model physics and more
specifically as a way of evaluating the success of the naturalness paradigm.
While the LHC experiments have ruled out much of the relevant parameter space,
there are "stop gaps", i.e., values of sparticle masses for which existing LHC
analyses have relatively little sensitivity to light stops. We point out that
techniques involving on-shell constrained M_2 variables can do much to enhance
sensitivity in this region and hence help close the stop gaps. We demonstrate
the use of these variables for several benchmark points and describe the effect
of realistic complications, such as detector effects and combinatorial
backgrounds, in order to provide a useful toolkit for light stop searches in
particular, and new physics searches at the LHC in general.Comment: 49 pages, 28 figures, revised version published in JHEP, references
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