619 research outputs found
Higgs Couplings in Composite Models
We study Higgs couplings in the composite Higgs model based on the coset
SO(5)/SO(4). We show that the couplings to gluons and photons are insensitive
to the elementary-composite mixings and thus not affected by light fermionic
resonances. Moreover, at leading order in the mixings the Higgs couplings to
tops and gluons, when normalized to the Standard Model (SM), are equal. These
properties are shown to be direct consequences of the Goldstone symmetry and of
the assumption of partial compositeness. In particular, they are independent of
the details of the elementary-composite couplings and, under the further
assumption of CP invariance, they are also insensitive to derivative
interactions of the Higgs with the composite resonances. We support our
conclusions with an explicit construction where the SM fermions are embedded in
the 14 dimensional representation of SO(5).Comment: 13 pages, 3 figures, 2 tables; v2: small improvements in the
discussion, results unchanged; typos corrected; one reference added. Matches
version submitted to PR
RELATIONSHIP OF DOCOSAHEXAENOIC ACID SUPPLEMENTATION AND INSULINE RESISTANCE IN OBESE CHILDREN
BACKGROUND: obesity may be associated with a later onset of chronic disorders and clinical complications. Insulin resistance, glucose intolerance and hyperinsulinemia are major components of the metabolic syndrome, which is highly prevalent among children and adolescents with severe obesity. Low levels of LCPUFAs, especially docosahexaenoic acid (C22:6 n-3, [DHA]) and a high n-6/n-3 LCPUFA ratio in skeletal muscle membrane phospholipids have been associated with insulin resistance in adults. Recent data suggest that the synthesis of DHA differs between obese children and normal weight children. In particular, in obese children, the highest quartile of BMI z-score was associated with higher plasma levels of the n-6/n-3 LCPUFA ratio. Given the high prevalence of insulin resistance in childhood obesity, we asked whether supplementation with DHA would be more effective than diet and physical activity alone in reducing this metabolic alteration.
AIM: to determine whether DHA supplementation, in addition to adequate diet and lifestyle, may reduce insulin resistance compared with diet and physical activity only, in obese children. Secondary aims were to evaluate whether may exist an association of the change of steatosis degree after the intervention with DHA supplementation...
SUBJECTS AND METHODS: this is a multicenter, longitudinal, double-blind, randomized, placebo-controlled trial that started on January 01, 2010. Up to September 30, 2012, thirty (14 boys, 16 girls, mean [SD] age, 11.4 [1.29] years, range 8-13), were recruited. All obese children consecutively admitted to the Department of Paediatrics, San Paolo Hospital, Milan, and to the Department of Paediatrics, Federico II Hospital, Naples, for routine examinations were assessed for eligibility. The study protocol scheduled daily oral supplementation of either an intervention \u201cproduct\u201d, that is two capsule of purified DHA (500 mg) or two capsule of wheat germ oil (500 mg). A nutritional-behavioural intervention was additionally recommended in all recruited children promoting a normocaloric balanced diet and an active lifestyle based on the Italian guidelines for treatment of childhood obesity. Additional recommendations were given to engage in a moderate daily exercise program (30-45 minutes/day aerobic physical exercise), tailored to individual preferences. Children were visited at the care centers within 3\ub11 days (baseline) after enrolment, and at 6 months after starting intervention. Evaluations included anthropometrical measurements, nutritional, metabolic assessment and liver ultrasonography.
Children were randomly assigned to the intervention or control group based on a computer generated, blocked randomization list by each center. A block size of four was used, stratified according to gender. The investigator who generated the randomization sequence was independent of the research staff and unaware of children.
RESULTS: at baseline there was no significant difference between groups for any anthropometrical (minimum P= 0.806) or dietary (minimum P= 0.318) or biochemical (minimum P=0.539) variable.
No significant difference among groups occurred for daily intake of energy or any macronutrient and the end of the study (minimum P=0.111).
At the end of the intervention a significant reduction of plasma fasting glucose (DHA group P=0.046; placebo group P=0.048), insulin (DHA group P=0.001; placebo group P=0.048) and HOMA (DHA group P=0.001; placebo group P=0.050) in both groups was observed. A higher percentage variation of plasma fasting insulin (P=0.0046) and HOMA (P=0.0045) in DHA than placebo group was showed.
There was a difference between groups for percentage reduction of liver steatosis: in DHA group from 14 to 7 % (P=0.655), in placebo group from 20 to 13 % (P=0.275)
Early (and Later) LHC Search Strategies for Broad Dimuon Resonances
Resonance searches generally focus on narrow states that would produce a
sharp peak rising over background. Early LHC running will, however, be
sensitive primarily to broad resonances. In this paper we demonstrate that
statistical methods should suffice to find broad resonances and distinguish
them from both background and contact interactions over a large range of
previously unexplored parameter space. We furthermore introduce an angular
measure we call ellipticity, which measures how forward (or backward) the muon
is in eta, and allows for discrimination between models with different parity
violation early in the LHC running. We contrast this with existing angular
observables and demonstrate that ellipticity is superior for discrimination
based on parity violation, while others are better at spin determination.Comment: 31 pages, 19 figures. References added, minor modifications made to
section
Non-universal minimal Z' models: present bounds and early LHC reach
We consider non-universal 'minimal' Z' models, whose additional U(1) charge
is a non-anomalous linear combination of the weak hypercharge Y, the baryon
number B and the partial lepton numbers (L_e, L_mu, L_tau), with no exotic
fermions beyond three standard families with right-handed neutrinos. We show
that the observed pattern of neutrino masses and mixing can be fully reproduced
by a gauge-invariant renormalizable Lagrangian, and flavor-changing neutral
currents in the charged lepton sector are suppressed by a GIM mechanism. We
then discuss the phenomenology of some benchmark models. The electrophilic
B-3L_e model is significantly constrained by electroweak precision tests, but
still allows to fit the hint of an excess observed by CDF in dielectrons but
not in dimuons. The muonphilic B-3L_mu model is very mildly constrained by
electroweak precision tests, so that even the very early phase of the LHC can
explore significant areas of parameter space. We also discuss the hadrophobic
L_mu-L_tau model, which has recently attracted interest in connection with some
puzzling features of cosmic ray spectra.Comment: 29 pages, 13 figure
Minimal Z' models: present bounds and early LHC reach
We consider `minimal' Z' models, whose phenomenology is controlled by only
three parameters beyond the Standard Model ones: the Z' mass and two effective
coupling constants. They encompass many popular models motivated by grand
unification, as well as many arising in other theoretical contexts. This
parameterization takes also into account both mass and kinetic mixing effects,
which we show to be sizable in some cases. After discussing the interplay
between the bounds from electroweak precision tests and recent direct searches
at the Tevatron, we extend our analysis to estimate the early LHC discovery
potential. We consider a center-of-mass energy from 7 towards 10 TeV and an
integrated luminosity from 50 to several hundred pb^-1, taking all existing
bounds into account. We find that the LHC will start exploring virgin land in
parameter space for M_Z' around 700 GeV, with lower masses still excluded by
the Tevatron and higher masses still excluded by electroweak precision tests.
Increasing the energy up to 10 TeV, the LHC will start probing a wider range of
Z' masses and couplings, although several hundred pb^-1 will be needed to
explore the regions of couplings favored by grand unification and to overcome
the Tevatron bounds in the mass region around 250 GeV.Comment: 25 pages. v2: small improvements and minor corrections, version
accepted for publication on JHE
Effects of β2-receptor stimulation by indacaterol in chronic heart failure treated with selective or non-selective β-blockers: a randomized trial
Alveolar \u3b22-receptor blockade worsens lung diffusion in heart failure (HF). This effect could be mitigated by stimulating alveolar \u3b22-receptors. We investigated the safety and the effects of indacaterol on lung diffusion, lung mechanics, sleep respiratory behavior, cardiac rhythm, welfare, and exercise performance in HF patients treated with a selective (bisoprolol) or a non-selective (carvedilol) \u3b2-blocker. Study procedures were performed before and after indacaterol and placebo treatments according to a cross-over, randomized, double-blind protocol in forty-four patients (27 on bisoprolol and 17 on carvedilol). No differences between indacaterol and placebo were observed in the whole population except for a significantly higher VE/VCO2 slope and lower maximal PETCO2 during exercise with indacaterol, entirely due to the difference in the bisoprolol group (VE/VCO2 31.8\u2009\ub1\u20095.9 vs. 28.5\u2009\ub1\u20095.6, p\u2009<\u20090.0001 and maximal PETCO2 36.7\u2009\ub1\u20095.5 vs. 37.7\u2009\ub1\u20095.8\u2009mmHg, p\u2009<\u20090.02 with indacaterol and placebo, respectively). In carvedilol, indacaterol was associated with a higher peak heart rate (119\u2009\ub1\u200934 vs. 113\u2009\ub1\u200930 bpm, with indacaterol and placebo) and a lower prevalence of hypopnea during sleep (3.8 [0.0;6.3] vs. 5.8 [2.9;10.5] events/hour, with indacaterol and placebo). Inhaled indacaterol is well tolerated in HF patients, it does not influence lung diffusion, and, in bisoprolol, it increases ventilation response to exercise
Product Differentiation Costs and Global Competition
The growing competitive intensity on the markets determines the emergence of
competition costs that are expressed at a corporate level and have implicit
repercussions for the supply system. This type of costs makes it possible to identify
a close link between competition costs and supply differentiation costs.
Classification by competitive intensity presupposes that the analysis performed
identifies the classification of company costs as the discriminating element, in
terms of the competitive pressure of the context in which the firm operates.
The emergence of competition costs is linked to an attempt to squeeze them as an
aspect of vertical, or more specifically, horizontal cooperation strategies.Product Differentiation; Differentiation Costs; Over-Supply; Global Competition; Marketing; Market-Driven Management; Global Corporations; Global Markets DOI:http://dx.doi.org/10.4468/2005.1.06garbelli
Higgs Mass from D-Terms: a Litmus Test
We explore supersymmetric theories in which the Higgs mass is boosted by the
non-decoupling D-terms of an extended gauge symmetry, defined here to
be a general linear combination of hypercharge, baryon number, and lepton
number. Crucially, the gauge coupling, , is bounded from below to
accommodate the Higgs mass, while the quarks and leptons are required by gauge
invariance to carry non-zero charge under . This induces an irreducible
rate, BR, for relevant to
existing and future resonance searches, and gives rise to higher dimension
operators that are stringently constrained by precision electroweak
measurements. Combined, these bounds define a maximally allowed region in the
space of observables, (BR, ), outside of which is excluded by
naturalness and experimental limits. If natural supersymmetry utilizes
non-decoupling D-terms, then the associated boson can only be observed
within this window, providing a model independent `litmus test' for this broad
class of scenarios at the LHC. Comparing limits, we find that current LHC
results only exclude regions in parameter space which were already disfavored
by precision electroweak data.Comment: 7 pages, 9 figure
Low Scale Flavor Gauge Symmetries
We study the possibility of gauging the Standard Model flavor group. Anomaly
cancellation leads to the addition of fermions whose mass is inversely
proportional to the known fermion masses. In this case all flavor violating
effects turn out to be controlled roughly by the Standard Model Yukawa,
suppressing transitions for the light generations. Due to the inverted
hierarchy the scale of new gauge flavor bosons could be as low as the
electroweak scale without violating any existing bound but accessible at the
Tevatron and the LHC. The mechanism of flavor protection potentially provides
an alternative to Minimal Flavor Violation, with flavor violating effects
suppressed by hierarchy of scales rather than couplings.Comment: 24 pages + appendices; v2) Refs. added and numerical examples
improved. Results unchanged; v3) small typos in appendix B correcte
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