Radiative corrections in a minimal extension of the standard model

Radiative corrections are studied within an extension of the standard model, containing extra singlet scalars. The calculations determine the effect of a large width of the Higgs boson on radiative corrections. They throw some light on the treatment of unstable particles inside loop-graphs.Comment: 5 pages, LaTeX, 1 eps-figur

A higher dimensional explanation of the excess of Higgs-like events at CERN LEP

Searches for the SM Higgs boson by the four LEP experiments have found a 2.3 sigma excess at 98 GeV and a smaller 1.7 sigma at around 115 GeV. We interpret these excesses as evidence for a Higgs boson coupled to a higher dimensional singlet scalar. The fit implies a relatively low dimensional mixing scale mu_{lhd} < 50 GeV, which explains the low confidence level found for the background fit in the range s^{1/2} > 100 GeV. The data show a slight preference for a five-dimensional over a six-dimensional field. This Higgs boson cannot be seen at the LHC, but can be studied at the ILC.Comment: 9 page

New spectra in the HEIDI Higgs models

We study the so-called HEIDI models, which are renormalizable extensions of the standard model with a higher dimensional scalar singlet field. As an additional parameter we consider a higher-dimensional mixing mass parameter. This leads to enriched possibilities compared to a previous study. We find effective spectral densities of the Higgs propagator, consisting of one, two or no particle peaks, together with a continuum. We compare with the LEP-2 data and determine for which range of the model parameters the data can be described. Assuming two peaks to be present we find for the new mass scale \nu\approx 56\pm12 \gev, largely independent of the dimension. In the limiting case of $d\rightarrow 6$ and two peaks we find a higher dimensional coupling constant $\alpha_6=0.70 \pm 0.18$, indicative of strong interactions among the higher dimensional fields. The LHC will not be able to study this Higgs field.Comment: 17 pages, 4 figure

Three-Loop Electroweak Correction to the Rho Parameter in the Large Higgs Mass Limit

We present an analytical calculation of the leading three-loop radiative correction to the rho-parameter in the Standard Model in the large Higgs mass limit. This correction, of order g^6 m_H^4/M_W^4, is opposite in sign to the leading two-loop correction of order g^4 m_H^2/M_W^2. The two corrections cancel each other for a Higgs mass of approximately 480 GeV. The result shows that it is extremely unlikely that a strongly interacting Higgs sector could fit the data of electroweak precision measurements.Comment: 15 pages, late

Three-loop electroweak corrections to the W-boson mass and sin^2 theta_eff in the large Higgs mass limit

We present an analytical calculation of the leading three-loop radiative correction to the S-parameter in the Standard Model in the large Higgs mass limit. Numerically, S^(3) = 1.1105*g^4/(1024 pi^3)*m_H^4/M_W^4. When combined with the corresponding three-loop correction to the rho-parameter, this leads to shifts of Delta^(3) sin^2 theta_eff = 4.6*10^-9*m_H^4/M_W^4 in the effective weak mixing angle and Delta^(3) M_W = -6.3*10^-4*MeV*m_H^4/M_W^4 in the W boson mass. For both of these observables, the sign of the three-loop correction is equal to that of the one-loop correction.Comment: 12 pages, two Figure

An axially-symmetric Newtonian Boson Star

A new solution to the coupled gravitational and scalar field equations for a condensed boson field is found in Newtonian approximation. The solution is axially symmetric, but not spherically symmetric. For N particles the mass of the object is given by $M = Nm - 0.02298 N^3 G_N^2 m^5$, to be compared with $M = Nm - 0.05426 N^3 G_N^2 m^5$ for the spherically symmetric case.Comment: 4 pages, figures available on reques

The weight of matter

Einstein's traceless 1919 gravitational theory is analyzed from a variational viewpoint. It is shown to be equivalent to a transverse (invariant only under diffeomorphisms that preserve the Lebesgue measure) theory, with an additional Weyl symmetry, in which the gauge is partially fixed so that the metric becomes unimodular. In spite of the fact that this symmetry forbids direct coupling of the potential energy with the gravitational sector, the equivalence principle is recovered in the unimodular gauge owing to Bianchi's identities.Comment: LaTeX, 11 page

Gravitational anomaly and fundamental forces

I present an argument, based on the topology of the universe, why there are three generations of fermions. The argument implies a preferred gauge group of SU(5), but with SO(10) representations of the fermions. The breaking pattern SU(5) to SU(3)xSU(2)xU(1) is preferred over the pattern SU(5) to SU(4)xU(1). On the basis of the argument one expects an asymmetry in the early universe microwave data, which might have been detected already.Comment: Contribution to the 2nd School and Workshop on Quantum Gravity and Quantum Geometry. Corfu, september 13-20 2009. 10 page

Non--decoupling, triviality and the ρ\rho parameter

The dependence of the $\rho$ parameter on the mass of the Higgs scalar and the top quark is computed non--perturbatively using the $1/N_F$ expansion in the standard model. We find an explicit expression for the $\rho$ parameter that requires the presence of a physical cutoff. This should come as no surprise since the theory is presumably trivial. By taking this cutoff into account, we find that the $\rho$ parameter can take values only within a limited range and has finite ambiguities that are suppressed by inverse powers of the cutoff scale, the so called ``scaling--violations". We find that large deviations from the perturbative results are possible, but only when the cutoff effects are also large.Comment: 16pp, Figures NOT included, harvmac, minor modifications incl. wording, refs., UCLA/92/TEP/23,OHSTPY-HEP-T-92-00

Corrections to oblique parameters induced by anomalous vector boson couplings

We study quadratically divergent radiative corrections to the oblique parameters at LEP1 induced by non-standard vector boson self-couplings. We work in the Stueckelberg formalism and regulate the divergences through a gauge-invariant higher derivative scheme. Using consistency arguments together with the data we find a limit on the anomalous magnetic moment Delta kappa of the W-boson, |Delta kappa| <= 0.26.Comment: 32 pages, LaTeX; cross reference corrected, minor beautifications, version to be published in Phys.Rev.