87 research outputs found
Does the `Higgs' have Spin Zero?
The Higgs boson is predicted to have spin zero. The ATLAS and CMS experiments
have recently reported of an excess of events with mass ~ 125 GeV that has some
of the characteristics expected for a Higgs boson. We address the questions
whether there is already any evidence that this excess has spin zero, and how
this possibility could be confirmed in the near future. The excess observed in
the gamma gamma final state could not have spin one, leaving zero and two as
open possibilities. We calculate the angular distribution of gamma gamma pairs
from the decays of a spin-two boson produced in gluon-gluon collisions, showing
that is unique and distinct from the spin-zero case. We also calculate the
distributions for lepton pairs that would be produced in the W W* decays of a
spin-two boson, which are very different from those in Higgs decays, and note
that the kinematics of the event selection used to produce the excess observed
in the W W* final state have reduced efficiency for spin two.Comment: 22 pages, 22 figures, Version accepted for publication in JHEP,
includes additional plots of dilepton mass distribution
Testing supersymmetry at the LHC through gluon-fusion production of a slepton pair
Renormalizable quartic couplings among new particles are typical of
supersymmetric models. Their detection could provide a test for supersymmetry,
discriminating it from other extensions of the Standard Model. Quartic
couplings among squarks and sleptons, together with the SU(3) gauge couplings
for squarks, allow a new realization of the gluon-fusion mechanism for
pair-production of sleptons at the one-loop level. The corresponding production
cross section, however, is at most of fb for slepton and squark
masses of GeV. We then extend our investigation to the
gluon-fusion production of sleptons through the exchange of Higgs bosons. The
cross section is even smaller, of fb, if the exchanged Higgs
boson is considerably below the slepton-pair threshold, but it is enhanced when
it is resonant. It can reach fb for the production of sleptons
of same-chirality, exceeding these values for 's of
opposite-chirality, even when chirality-mixing terms in the squark sector are
vanishing. The cross section can be further enhanced if these mixing terms are
nonnegligible, providing a potentially interesting probe of the Higgs sector,
in particular of parameters such as , , and .Comment: 28 pages, 11 figure
Multi-Photon Signals from Composite Models at LHC
We analyze the collider signals of composite scalars that emerge in certain
little Higgs models and models of vectorlike confinement. Similar to the decay
of the pion into photon pairs, these scalars mainly decay through
anomaly-induced interactions into electroweak gauge bosons, leading to a
distinct signal with three or more photons in the final state. We study the
standard model backgrounds for these signals, and find that the LHC can
discover these models over a large range of parameter space with 30 fb
at 14 TeV. An early discovery at the current 7 TeV run is possible in some
regions of parameter space. We also discuss possibilities to measure the spin
of the particles in the and decay channels.Comment: 18 pages, LaTe
Beneficial effect of Sparassis crispa on stroke through activation of Akt/eNOS pathway in brain of SHRSP
Sparassis crispa (S. crispa) is a mushroom used as a natural medicine that recently became cultivatable in Japan. In this study, we investigated not only the preventive effects of S. crispa against stroke and hypertension in stroke-prone spontaneously hypertensive rats (SHRSP) but also the mechanism involved by using studies of the cerebral cortex at a young age. Six-week-old male SHRSP were divided into 2 groups, a control group and an S. crispa group administered 1.5% S. crispa in feed, and we then observed their survival. In addition, rats of the same age were treated with 1.5% S. crispa for 4 weeks and we measured body weight, blood pressure, blood flow from the tail, NOx production, and the levels of expression of several proteins in the cerebral cortex by western blot analysis. Our results showed that the S. crispa group had a delayed incidence of stroke and death and significantly decreased blood pressure and increased blood flow after the administration. Moreover, the quantity of urinary excretion and the nitrate/nitrite concentration in cerebral tissue were higher than those of control SHRSP rats. In the cerebral cortex, phosphor-eNOS (Ser1177) and phosphor-Akt (Ser473) in S. crispa-treated SHRSP were increased compared with those of control SHRSP rats. In conclusion, S. crispa could ameliorate cerebrovascular endothelial dysfunction by promoting recovery of Akt-dependent eNOS phosphorylation and increasing NO production in the cerebral cortex. S. crispa may be useful for preventing stroke and hypertension
Twenty Years of SUGRA
A brief review is given of the developments of mSUGRA and its extensions
since the formulation of these models in 1982. Future directions and prospects
are also discussed.Comment: Invited talk at the International Conference BEYOND-2003, Schloss
Ringberg, Germany, June 10-14, 2003; 21 pages, Late
Primary ciliogenesis defects are associated with human astrocytoma/glioblastoma cells
<p>Abstract</p> <p>Background</p> <p>Primary cilia are non-motile sensory cytoplasmic organelles that have been implicated in signal transduction, cell to cell communication, left and right pattern embryonic development, sensation of fluid flow, regulation of calcium levels, mechanosensation, growth factor signaling and cell cycle progression. Defects in the formation and/or function of these structures underlie a variety of human diseases such as Alström, Bardet-Biedl, Joubert, Meckel-Gruber and oral-facial-digital type 1 syndromes. The expression and function of primary cilia in cancer cells has now become a focus of attention but has not been studied in astrocytomas/glioblastomas. To begin to address this issue, we compared the structure and expression of primary cilia in a normal human astrocyte cell line with five human astrocytoma/glioblastoma cell lines.</p> <p>Methods</p> <p>Cultured normal human astrocytes and five human astrocytoma/glioblastoma cell lines were examined for primary cilia expression and structure using indirect immunofluorescence and electron microscopy. Monospecific antibodies were used to detect primary cilia and map the relationship between the primary cilia region and sites of endocytosis.</p> <p>Results</p> <p>We show that expression of primary cilia in normal astrocytes is cell cycle related and the primary cilium extends through the cell within a unique structure which we show to be a site of endocytosis. Importantly, we document that in each of the five astrocytoma/glioblastoma cell lines fully formed primary cilia are either expressed at a very low level, are completely absent or have aberrant forms, due to incomplete ciliogenesis.</p> <p>Conclusions</p> <p>The recent discovery of the importance of primary cilia in a variety of cell functions raises the possibility that this structure may have a role in a variety of cancers. Our finding that the formation of the primary cilium is disrupted in cells derived from astrocytoma/glioblastoma tumors provides the first evidence that altered primary cilium expression and function may be part of some malignant phenotypes. Further, we provide the first evidence that ciliogenesis is not an all or none process; rather defects can arrest this process at various points, particularly at the stage subsequent to basal body association with the plasma membrane.</p
Phenomenology of the Higgs effective Lagrangian via FeynRules
The Higgs discovery and the lack of any other hint for new physics favor a description of non-standard Higgs physics in terms of an effective field theory. We present an implementation of a general Higgs effective Lagrangian containing operators up to dimension six in the framework of FeynRules and provide details on the translation between the mass and interaction bases, in particular for three- and four-point interaction vertices involving Higgs and gauge bosons. We illustrate the strengths of this implementation by using the UFO interface of FeynRules capable to generate model files that can be understood by the MadGraph 5 event generator and that have the specificity to contain all interaction vertices, without any restriction on the number of external legs or on the complexity of the Lorentz structures. We then investigate several new physics effects in total rates and differential distributions for different Higgs production modes, including gluon fusion, associated production with a gauge boson and di-Higgs production. We finally study contact interactions of gauge and Higgs bosons to fermions
Complete Higgs sector constraints on dimension-6 operators
Constraints on the full set of Standard Model dimension-6 operators have previously used triple-gauge couplings to complement the constraints obtainable from Higgs signal strengths. Here we extend previous analyses of the Higgs sector constraints by including information from the associated production of Higgs and massive vector bosons (H+V production), which excludes a direction of limited sensitivity allowed by partial cancellations in the triple-gauge sector measured at LEP. Kinematic distributions in H+V production provide improved sensitivity to dimension-6 operators, as we illustrate here with simulations of the invariant mass and pT distributions measured by D0 and ATLAS, respectively. We provide bounds from a global fit to a complete set of CP-conserving operators affecting Higgs physics
Extracellular Administration of BCL2 Protein Reduces Apoptosis and Improves Survival in a Murine Model of Sepsis
Severe sepsis and septic shock are major causes of morbidity and mortality worldwide. In experimental sepsis there is prominent apoptosis of various cell types, and genetic manipulation of death and survival pathways has been shown to modulate organ injury and survival.We investigated the effect of extracellular administration of two anti-apoptotic members of the BCL2 (B-cell lymphoma 2) family of intracellular regulators of cell death in a murine model of sepsis induced by cecal ligation and puncture (CLP). We show that intraperitoneal injection of picomole range doses of recombinant human (rh) BCL2 or rhBCL2A1 protein markedly improved survival as assessed by surrogate markers of death. Treatment with rhBCL2 or rhBCL2A1 protein significantly reduced the number of apoptotic cells in the intestine and heart following CLP, and this was accompanied by increased expression of endogenous mouse BCL2 protein. Further, mice treated with rhBCL2A1 protein showed an increase in the total number of neutrophils in the peritoneum following CLP with reduced neutrophil apoptosis. Finally, although neither BCL2 nor BCL2A1 are a direct TLR2 ligand, TLR2-null mice were not protected by rhBCL2A1 protein, indicating that TLR2 signaling was required for the protective activity of extracellularly adminsitered BCL2A1 protein in vivo.Treatment with rhBCL2A1 or rhBCL2 protein protects mice from sepsis by reducing apoptosis in multiple target tissues, demonstrating an unexpected, potent activity of extracellularly administered BCL2 BH4-domain proteins
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