13,400 research outputs found
Electroweak and supersymmetry breaking from the Higgs discovery
We will explore the consequences on the electroweak breaking condition, the
mass of supersymmetric partners and the scale at which supersymmetry is broken,
for arbitrary values of the supersymmetric parameters tan(beta) and the stop
mixing X_t, which follow from the Higgs discovery with a mass m_H\simeq 126 GeV
at the LHC. Within the present uncertainty on the top quark mass we deduce that
radiative breaking requires tan(beta) \gtrsim 7 for maximal mixing X_t\simeq
\sqrt{6}, and tan(beta) \gtrsim 20 for small mixing X_t\lesssim 1. The scale at
which supersymmetry is broken \mathcal M can be of order the unification or
Planck scale only for large values of tan(beta) and negligible mixing X_t\simeq
0. On the other hand for maximal mixing and large values of tan(beta)
supersymmetry should break at scales as low as \mathcal M\simeq 10^5 GeV. The
uncertainty in those predictions stemming from the uncertainty in the top quark
mass, i.e. the top Yukawa coupling, is small (large) for large (small) values
of tan(beta). In fact for tan(beta)=1 the uncertainty on the value of \mathcal
M is of several orders of magnitude.Comment: 16 pages, 7 figures; v2: numerical typo corrected in codes, and 2
loop radiative corrections added. Some conclusions slightly change
GMSB with Light Stops
Gauge mediated supersymmetry breaking (GMSB) is an elegant mechanism to
transmit supersymmetry breaking from the hidden to the MSSM observable sector,
which solves the supersymmetric flavor problem. However the smallness of the
generated stop mixing requires superheavy stops to reproduce the experimental
value of the Higgs mass. Two possible ways out are: i) To extend GMSB by direct
superpotential messenger-MSSM Yukawa couplings to generate sizeable mixing,
thus reintroducing the flavor problem; ii) To extend the MSSM Higgs sector with
singlets and/or triplets providing extra tree-level corrections to the Higgs
mass. Singlets will not get any soft mass from GMSB and triplets will
contribute to the parameter which could be an issue. In this paper we
explore the second way by introducing extra supersymmetric triplets with
hypercharges , with a tree-level custodial global symmetry in the Higgs sector protecting the parameter: a
supersymmetric generalization of the Georgi-Machacek model, dubbed as
supersymmetric custodial triplet model (SCTM). The renormalization group
running from the messenger to the electroweak scale mildly breaks the custodial
symmetry. We will present realistic low-scale scenarios (with the NLSP being a
Bino-like neutralino or the right-handed stau) based on general (non-minimal)
gauge mediation and consistent with all present experimental data. Their main
features are: i) Light ( TeV) stops; ii) Exotic couplings ( and ) absent in the MSSM and proportional to the
triplets VEV, ; and, iii) A possible (measurable) universality
breaking of the Higgs couplings .Comment: 21 pages, 9 figures; v2: references adde
Cooperative Glutamatergic and Cholinergic Mechanisms Generate Short-Term Modifications of Synaptic Effectiveness in Prepositus Hypoglossi Neurons
To maintain horizontal eye position on a visual target after a saccade, extraocular motoneurons need a persistent (tonic) neural activity, called "eye-position signal," generated by prepositus hypoglossi (PH) neurons. We have shown previously in vitro and in vivo that this neural activity depends, among others mechanisms, on the interplay of glutamatergic transmission and cholinergic synaptically triggered depolarization. Here, we used rat sagittal brainstem slices, including PH nucleus and paramedian pontine reticular formation (PPRF). We made intracellular recordings of PH neurons and studied their synaptic activation from PPRF neurons. Train stimulation of the PPRF area evoked a cholinergic-sustained depolarization of PH neurons that outlasted the stimulus. EPSPs evoked in PH neurons by single pulses applied to the PPRF presented a short-term potentiation (STP) after train stimulation. APV (an NMDA-receptor blocker) or chelerythrine (a protein kinase-C inhibitor) had no effect on the sustained depolarization, but they did block the evoked STP, whereas pirenzepine (an M1 muscarinic antagonist) blocked both the sustained depolarization and the STP of PH neurons. Thus, electrical stimulation of the PPRF area activates both glutamatergic and cholinergic axons terminating in the PH nucleus, the latter producing a sustained depolarization probably involved in the genesis of the persistent neural activity required for eye fixation. M1-receptor activation seems to evoke a STP of PH neurons via NMDA receptors. Such STP could be needed for the stabilization of the neural network involved in the generation of position signals necessary for eye fixation after a saccade
Dark Matter from the Supersymmetric Custodial Triplet Model
The Supersymmetric Custodial Triplet Model (SCTM) adds to the particle
content of the MSSM three triplet chiral superfields with hypercharge
. At the superpotential level the model respects a global symmetry only broken by the Yukawa interactions. The pattern
of vacuum expectation values of the neutral doublet and triplet scalar fields
depends on the symmetry pattern of the Higgs soft breaking masses. We study the
cases where this symmetry is maintained in the Higgs sector, and when it is
broken only by the two doublets attaining different vacuum expectation values.
In the former case, the symmetry is spontaneously broken down to the vectorial
subgroup and the parameter is protected by the custodial
symmetry. However in both situations the parameter is protected at tree
level, allowing for light triplet scalars with large vacuum expectation values.
We find that over a large range of parameter space, a light neutralino can
supply the correct relic abundance of dark matter either through resonant
s-channel triplet scalar funnels or well tempering of the Bino with the triplet
fermions. Direct detection experiments have trouble probing these model points
because the custodial symmetry suppresses the coupling of the neutralino and
the and a small Higgsino component of the neutralino suppresses the
coupling with the Higgs. Likewise the annihilation cross sections for indirect
detection lie below the Fermi-LAT upper bounds for the different channels.Comment: 26 pages, 8 figures; v2 revised comments on classification method and
indirect detection section. Results unchanged, matches PRD published versio
Effects of insecticidal ketones present in mint plants on GABA A receptor from mammalian neurons
The genus Mentha, an important member of the Lamiaceae family, is represented by many species commonly known as mint. The insecticidal activity of Mentha oil and its main components has been tested and established against various insects/pests. Among these, the ketone monoterpenes that are most common in different Mentha species demonstrated insect toxicity, with pulegone being the most active, followed by carvone and menthone. Considering that the GABAA receptor (GABAA-R) is one of the main insecticide targets on neurons, and that pulegone would modulate the insect GABA system, it may be expected that the insecticidal properties of Mentha ketones are mediated by their interaction with this receptor.Fil: Sánchez, Mariela Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; ArgentinaFil: Delgado Marín, Leticia Ester. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; ArgentinaFil: Garcia, Daniel Asmed. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; Argentin
Understanding the Relationship between Customer Concentration and Profitability in Public Firms in the Electronics Manufacturing Industry
This study investigates the relationship between a supplier’s profitability and their major customers. Previous literature concerning a firm’s customer makeup and their profitability have produced two general conclusions. The first conclusion is that there is a negative correlation due to the power imbalance major customers gain over their suppliers, resulting in lower prices, overextended credit accounts, and inconsistent cash payments for the goods provided by the supplier. Other literature argues that there is a positive correlation due to mutual dependence between a customer and its supplier causing an increase in information sharing and joint actions, resulting in a higher profitability for the supplier. This study analyzed 136 firms in the electronics manufacturing industry in 2017 and found a positive and significant correlation between customer concentration and a supplier’s profitability. The analysis also found a positive but insignificant correlation between mutual dependence and a supplier’s profitability. The results suggest that gained efficiencies from greater customer concentration outweigh the effects of a disadvantageous power imbalance by major customers
- …