3,855 research outputs found
The Strongly-Interacting Light Higgs
We develop a simple description of models where electroweak symmetry breaking
is triggered by a light composite Higgs, which emerges from a
strongly-interacting sector as a pseudo-Goldstone boson. Two parameters broadly
characterize these models: m_rho, the mass scale of the new resonances and
g_rho, their coupling. An effective low-energy Lagrangian approach proves to be
useful for LHC and ILC phenomenology below the scale m_rho. We identify two
classes of operators: those that are genuinely sensitive to the new strong
force and those that are sensitive to the spectrum of the resonances only.
Phenomenological prospects for the LHC and the ILC include the study of
high-energy longitudinal vector boson scattering, strong double-Higgs
production and anomalous Higgs couplings. We finally discuss the possibility
that the top quark could also be a composite object of the strong sector.Comment: 45 pages, 1 figure. v2: references adde
DNA waves and water
Some bacterial and viral DNA sequences have been found to induce low
frequency electromagnetic waves in high aqueous dilutions. This phenomenon
appears to be triggered by the ambient electromagnetic background of very low
frequency. We discuss this phenomenon in the framework of quantum field theory.
A scheme able to account for the observations is proposed. The reported
phenomenon could allow to develop highly sensitive detection systems for
chronic bacterial and viral infections.Comment: Invited talk at the DICE2010 Conference, Castiglioncello, Italy
September 201
Probing Split Supersymmetry with Cosmic Rays
A striking aspect of the recently proposed split supersymmetry is the
existence of heavy gluinos which are metastable because of the very heavy
squarks which mediate their decay. In this paper we correlate the expected flux
of these particles with the accompanying neutrino flux produced in inelastic
collisions in distant astrophysical sources. We show that an event rate at
the Pierre Auger Observatory of approximately 1 yr for gluino masses of
about 500 GeV is consistent with existing limits on neutrino fluxes. The
extremely low inelasticity of the gluino-containing hadrons in their collisions
with the air molecules makes possible a distinct characterization of the
showers induced in the atmosphere. Should such anomalous events be observed, we
show that their cosmogenic origin, in concert with the requirement that they
reach the Earth before decay, leads to a lower bound on their proper lifetime
of the order of 100 years, and consequently, to a lower bound on the scale of
supersymmetry breaking, GeV. Obtaining
such a bound is not possible in collider experiments.Comment: Version to be published in Phys. Rev.
Radiative seesaw and degenerate neutrinos
The radiative see-saw mechanism of Witten generates the right-handed neutrino
masses in SO(10) with the spinorial 16_H Higgs field. We study here
analytically the 2nd and 3rd generations for the minimal Yukawa structure
containing 10_H and 120_H Higgs representations. In the approximation of small
2nd generation masses and gauge loop domination we find the following results :
(1) b-tau unification, (2) natural coexistence between large theta_l and small
theta_q, (3) degenerate neutrinos.Comment: 4 page
The peripartum period influenced the serum macromineral profile in mares
Changes in metabolic requirements during pregnancy may produce nutritional imbalances predisposing mares to pathological conditions. Therefore, we aimed to examine changes in serum macrominerals during the peripartum period in mares. Fifteen pregnant mares (Group A) were monitored starting at the 263rd day of pregnancy until the 21st day after foaling. Seven non-pregnant and non-lactating mares were used as a control group (Group B). Group A was subjected to blood sampling within 24-12 h after parturition (P) and then 7, 14 and 21 days after foaling (C1, C2, C3 weeks, respectively). Group B was subjected to regular sampling throughout the study to ensure that seasonal changes had no significant effect on studied parameters. Serum samples were analysed for serum electrolytes including sodium (NaC), potassium (KC), calcium (CaCC), phosphorus (PC), chloride (Cl) and magnesium (MgCC). Two-way repeated measures of analysis of variance (ANOVA) was applied to evaluate significant effects of peripartum on electrolyte concentrations. Group A showed a decrease in Cl concentrations (P D 0:011) after foaling and lower PC concentrations (P D 0:015) compared to Group B throughout the study. The linear regression model showed an increase in NaC concentrations (P D 0:002) and a gradual decrease in serum CaCC (P D 0:001) during pregnancy. Because the most significant changes in serum electrolytes occurred within 2 weeks before and 2 weeks after foaling, monitoring serum electrolyte concentrations would indicate whether the mare needs further mineral supplementation at this stage. The significant changes in a mare's macromineral profile that we observed over the peripartum provide enhanced knowledge about mineral interrelations and their modifications during specific physiological conditions such as late pregnancy and early postpartum
Brane Cosmology and KK Gravitinos
The cosmology of KK gravitinos in models with extra dimensions is considered.
The main result is that the production of such KK modes is not compatible with
an epoch of non--standard expansion after inflation. This is so because the BBN
constraint on the zero mode forces the reduced five dimensional Planck mass
down to values much smaller than the usual four dimensional one, but this
in turn implies many KK states available for a given temperature. Once these
states are taken into account one finds that there is no for which the
produced KK gravitinos satisfy BBN and overclosure constraints. This conclusion
holds for both flat and warped models in which only gravity propagates in the
full spacetime.Comment: 19 pages, references added, IoP styl
Loop-Effects in Pseudo-Supersymmetry
We analyze the transmission of supersymmetry breaking in brane-world models
of pseudo-supersymmetry. In these models two branes preserve different halves
of the bulk supersymmetry. Thus supersymmetry is broken although each sector of
the model is supersymmetric when considered separately. The world-volume theory
on one brane feels the breakdown of supersymmetry only through two-loop
interactions involving a coupling to fields from the other brane. In a 5D toy
model with bulk vectors, we compute the diagrams that contribute to scalar
masses on one brane and find that the masses are proportional to the
compactification scale up to logarithmic corrections, m^2 ~ (2 pi R)^{-2}(ln(2
pi R ms)-1.1), where ms is an ultraviolet cutoff. Thus, for large
compactification radii, where this result is valid, the brane scalars acquire a
positive mass squared. We also compute the three-loop diagrams relevant to the
Casimir energy between the two branes and find E ~ (2 pi R)^{-4}((ln(2 pi R
ms)-1.7)^2+0.2). For large radii, this yields a repulsive Casimir force.Comment: Latex, 30 pages, 6 figures, v2: minor corrections, comments on susy
algebra and x^5 covariant derivative adde
comparison between thermal energy and acoustic emission for the fatigue behavior of steels
Abstract The paper is focused on the study of fatigue materials, using an energy approach, with the support of two different non-destructive techniques. Indeed, the analysis of the energy behavior was conducted by the simultaneous application of Acoustic Emission (AE) and Thermography (TH). The purpose of the paper was to compare and integrate the results obtained by the two methodologies to assess the fatigue behavior of materials. The experimental tests were carried out on flat steel specimens of steels commonly used for metal carpentry either under static loading or under sequences of increasing cyclic loading. The results allow to define the fatigue limit either by the thermography or by the acoustic emission and they are encouraging to continue the comparison and the integration between the two energetic methodologies
Higgs mass and vacuum stability in the Standard Model at NNLO
We present the first complete next-to-next-to-leading order analysis of the
Standard Model Higgs potential. We computed the two-loop QCD and Yukawa
corrections to the relation between the Higgs quartic coupling (lambda) and the
Higgs mass (Mh), reducing the theoretical uncertainty in the determination of
the critical value of Mh for vacuum stability to 1 GeV. While lambda at the
Planck scale is remarkably close to zero, absolute stability of the Higgs
potential is excluded at 98% C.L. for Mh < 126 GeV. Possible consequences of
the near vanishing of lambda at the Planck scale, including speculations about
the role of the Higgs field during inflation, are discussed.Comment: 35 pages, 8 figures. Final published version, misprints fixed,
figures update
Widespread extrahepatic expression of acute-phase proteins in healthy chicken (Gallus gallus) tissues
Acute phase proteins (APP) are plasma proteins that can modify their expression in response to inflammation caused by tissue injury, infections, immunological disorders or stress. Although APP are produced mainly in liver, extrahepatic production has also been described. As a prerequisite to get insight the expression of APP in chicken during diseases, this study investigated the presence of five APP, including alpha1-acid glycoprotein (AGP), Serum Amyloid A (SAA), PIT54, C-Reactive protein (CRP) and Ovotransferrin (OVT) in twenty tissues collected from healthy chicken (Gallus gallus) by quantitative Real Time PCR and immunohistochemistry. As expected, APP gene abundance was higher in liver compared with other tissues. The mRNA coding for CRP, OVT and SAA was detected in all analyzed tissues with a higher expression in gastrointestinal tract, respiratory and lymphatic samples. SAA expression was particularly high in cecal tonsil, lung, spleen and Meckel's diverticulum, whereas OVT in lung, bursa of Fabricius and pancreas. AGP and PIT54 mRNA expression were detected in all tissues but at negligible levels. Immunohistochemical expression of AGP and OVT was variably detected in different organs, being identified in endothelium of every tissue. Positive cells were present in the epithelium of the mucosal layer of gastrointestinal tract and kidney. Lung and central nervous system stained for both proteins. No positive staining was detected in lymphoid tissues and muscle. These results suggest that most tissues can express different amount of APP even in healthy conditions and are therefore capable to mount a local acute phase reaction
- âŠ