24 research outputs found
Precision Observables in the MSSM: W mass and the muon magnetic moment
The precision observables M_W and g-2 of the muon are discussed in the
framework of the MSSM. Recent progress in the evaluation of the theoretical
predictions is described, and the MSSM predictions are compared with the SM
predictions and the experimental values.Comment: 4 pages, 2 figures. To appear in Proceedings of SUSY06, the 14th
International Conference on Supersymmetry and the Unification of Fundamental
Interactions, UC Irvine, California, 12-17 June 200
Precise Prediction for M_W in the MSSM
We present the currently most accurate evaluation of the W boson mass, M_W,
in the Minimal Supersymmetric Standard Model (MSSM). The full complex phase
dependence at the one-loop level, all available MSSM two-loop corrections as
well as the full Standard Model result have been included. We analyse the
impact of the different sectors of the MSSM at the one-loop level with a
particular emphasis on the effect of the complex phases. We discuss the
prediction for M_W based on all known higher-order contributions in
representative MSSM scenarios. Furthermore we obtain an estimate of the
remaining theoretical uncertainty from unknown higher-order corrections.Comment: 38 pages, 25 figures. Minor corrections, additional reference
PASCal: A principal-axis strain calculator for thermal expansion and compressibility determination
We describe a web-based tool (PASCal; Principal Axis Strain Calculator) aimed
at simplifying the determination of principal coefficients of thermal expansion
and compressibilities from variable-temperature and variable-pressure lattice
parameter data. In a series of three case studies, we use PASCal to re-analyse
previously-published lattice parameter data and show that additional scientific
insight is obtainable in each case. First, the two-dimensional metal-organic
framework Cu-SIP-3 is found to exhibit the strongest area-negative thermal
expansion (NTE) effect yet observed; second, the widely-used explosive HMX
exhibits much stronger mechanical anisotropy than had previously been
anticipated, including uniaxial NTE driven by thermal changes in molecular
conformation; and, third, the high-pressure form of the mineral malayaite is
shown to exhibit a strong negative linear compressibility (NLC) effect that
arises from correlated tilting of SnO6 and SiO4 coordination polyhedra.Comment: 31 pages, 8 figures, formatted as preprint for J. Appl. Crys
Review of Top Quark Physics Results
As the heaviest known fundamental particle, the top quark has taken a central
role in the study of fundamental interactions. Production of top quarks in
pairs provides an important probe of strong interactions. The top quark mass is
a key fundamental parameter which places a valuable constraint on the Higgs
boson mass and electroweak symmetry breaking. Observations of the relative
rates and kinematics of top quark final states constrain potential new physics.
In many cases, the tests available with study of the top quark are both
critical and unique. Large increases in data samples from the Fermilab Tevatron
have been coupled with major improvements in experimental techniques to produce
many new precision measurements of the top quark. The first direct evidence for
electroweak production of top quarks has been obtained, with a resulting direct
determination of . Several of the properties of the top quark have been
measured. Progress has also been made in obtaining improved limits on potential
anomalous production and decay mechanisms. This review presents an overview of
recent theoretical and experimental developments in this field. We also provide
a brief discussion of the implications for further efforts.Comment: 119 pages, 55 figure
ROS-mediated PI3K activation drives mitochondrial transfer from stromal cells to hematopoietic stem cells in response to infection
Hematopoietic stem cells (HSCs) undergo rapid expansion in response to stress stimuli. Here we investigate the bioenergetic processes which facilitate the HSC expansion in response to infection. We find that infection by Gram-negative bacteria drives an increase in mitochondrial mass in mammalian HSCs, which results in a metabolic transition from glycolysis toward oxidative phosphorylation. The initial increase in mitochondrial mass occurs as a result of mitochondrial transfer from the bone marrow stromal cells (BMSCs) to HSCs through a reactive oxygen species (ROS)-dependent mechanism. Mechanistically, ROS-induced oxidative stress regulates the opening of connexin channels in a system mediated by phosphoinositide 3-kinase (PI3K) activation, which allows the mitochondria to transfer from BMSCs into HSCs. Moreover, mitochondria transfer from BMSCs into HSCs, in the response to bacterial infection, occurs before the HSCs activate their own transcriptional program for mitochondrial biogenesis. Our discovery demonstrates that mitochondrial transfer from the bone marrow microenvironment to HSCs is an early physiologic event in the mammalian response to acute bacterial infection and results in bioenergetic changes which underpin emergency granulopoiesis
Acute myeloid leukemia induces pro-tumoral p16INK4a driven senescence in the bone marrow microenvironment
Acute myeloid leukemia (AML) is an age-related disease that is highly dependent on the bone marrow (BM) microenvironment. With increasing age, tissues accumulate senescent cells, characterized by an irreversible arrest of cell proliferation and the secretion of a set of proinflammatory cytokines, chemokines, and growth factors, collectively known as the senescence-associated secretory phenotype (SASP). Here, we report that AML blasts induce a senescent phenotype in the stromal cells within the BM microenvironment and that the BM stromal cell senescence is driven by p16INK4a expression. The p16INK4a-expressing senescent stromal cells then feed back to promote AML blast survival and proliferation via the SASP. Importantly, selective elimination of p16INK4a 1 senescent BM stromal cells in vivo improved the survival of mice with leukemia. Next, we find that the leukemia-driven senescent tumor microenvironment is caused by AML-induced NOX2-derived superoxide. Finally, using the p16-3MR mouse model, we show that by targeting NOX2 we reduced BM stromal cell senescence and consequently reduced AML proliferation. Together, these data identify leukemia-generated NOX2-derived superoxide as a driver of protumoral p16INK4a-dependent senescence in BM stromal cells. Our findings reveal the importance of a senescent microenvironment for the pathophysiology of leukemia. These data now open the door to investigate drugs that specifically target the “benign” senescent cells that surround and support AML
Mass Bounds on a Very Light Neutralino
Within the Minimal Supersymmetric Standard Model (MSSM) we systematically
investigate the bounds on the mass of the lightest neutralino. We allow for
non-universal gaugino masses and thus even consider massless neutralinos, while
assuming in general that R-parity is conserved. Our main focus are laboratory
constraints. We consider collider data, precision observables, and also rare
meson decays to very light neutralinos. We then discuss the astrophysical and
cosmological implications. We find that a massless neutralino is allowed by all
existing experimental data and astrophysical and cosmological observations.Comment: 36 pages, 13 figures, minor modification in astro-physical bounds.
EPJC versio
The MSSM confronts the precision electroweak data and the muon g-2
We update the electroweak study of the predictions of the Minimal
Supersymmetric Standard Model (MSSM) including the recent results on the muon
anomalous magnetic moment, the weak boson masses, and the final precision data
on the Z boson parameters from LEP and SLC. We find that the region of the
parameter space where the slepton masses are a few hundred GeV is favored from
the muon g-2 for \tan\beta \ltsim 10, whereas for \tan\beta \simeq 50 heavier
slepton mass up to \sim 1000 GeV can account for the reported 3.2 \sigma
difference between its experimental value and the Standard Model (SM)
prediction. As for the electroweak measurements, the SM gives a good
description, and the sfermions lighter than 200 GeV tend to make the fit worse.
We find, however, that sleptons as light as 100 to 200 GeV are favored also
from the electroweak data, if we leave out the jet asymmetry data that do not
agree with the leptonic asymmetry data. We extend the survey of the preferred
MSSM parameters by including the constraints from the b \to s \gamma
transition, and find favorable scenarios in the minimal supergravity, gauge-,
and mirage-mediation models of supersymmetry breaking.Comment: 40 pages, 12 figures. v2: minor changes, references added, version to
appear in JHE
W mass and Leptonic Z-decays in the NMSSM
We study a subset of electroweak-precision observables consisting of ,
, and
(characterizing leptonic
-decays) in the context of the NMSSM. After a brief review of common
MSSM-NMSSM effects, e.g. for ,
which has been little discussed, even in the MSSM), specific NMSSM scenarios
are studied, with the result that the NMSSM, considering existing constraints
on its spectrum, is essentially consistent with available measurements, given
the current accuracy.Comment: 25 pages, 12 figure