arXiv subjects

Paolo Ciafaloni

Publications and source records attributed to Paolo Ciafaloni.

25 records · Page 2Linked to original sources

arXiv2001

Bloch-Nordsieck Violation in Spontaneously Broken Abelian Theories

We point out that, in a spontaneously broken U(1) gauge theory, inclusive processes, whose primary particles are mass eigenstates that do not coincide with the gauge eigenstates, are not free of infrared logarithms. The charge mixing allowed by symmetry breaking and the ensuing Bloch-Nordsieck violation are here analyzed in a few relevant cases and in particular for processes initiated by longitudinal gauge bosons. Of particular interest is the example of weak hypercharge in the Standard Model where, in addition, left-right mixing effects arise in transversely polarized fermion beams.

hep-ph↗

arXiv1999

Leading electroweak corrections at the TeV scale

The planned next generation of linear colliders (NLCs) will be able to probe the infrared structure of Standard Model electroweak interactions, that determines the behavior of electroweak radiative corrections at TeV scale energies. I present results of a recent calculation at the leading log level, and discuss my view on open issues and possible future developments of this new and interesting subject.

hep-ph↗

arXiv1999

Are electroweak corrections at 1 TeV under control at the 1 % level?

Future lepton colliders will provide a powerful tool for making precision experiments at energies that will range typically between 500 GeV and 2 TeV. At such high energies, one loop electroweak corrections are bigger than one could naively expect a priori. Thus, the calculation of higher order electroweak effects (and possibly their resummation) might be needed.

hep-ph↗

arXiv1998

Naturalness bounds on gauge mediated soft terms

After a general discussion about the quantitative meaning of the naturalness upper bounds on the masses of supersymmetric particles, we compute these bounds in models with gauge-mediated soft terms. We find interesting upper limits on the right-handed slepton masses that, unless the messenger fields are very light, disfavor minimal models with large messenger content. Deep unphysical minima, that however turn out to be not dangerous, are usually present in such models. The mu-problem can be solved by adding a light singlet only at the price of a large amount of fine tuning that gives also rise to heavy sparticles and large tanβ.

hep-ph↗

arXiv1997

Dynamical determination of the Supersymmetric Higgs mass

Considering the supersymmetric Higgs mass ($μ$-parameter) as a dynamical variable to be determined by minimizing the energy, we predict its value as a function of the soft masses of the potential. We find that $μ$ has a nonzero value close to the weak scale. This scenario offers a simultaneous solution to the doublet-triplet splitting problem and to the $μ$-problem. We discuss its viability in theories with gauge mediated supersymmetry breaking.

hep-ph↗

arXiv1995

Lepton Flavour Violations in SO(10) with large $\tanβ$

In supersymmetric~SO(10) with large $\tanβ$ and Yukawa coupling unification $λ_t=λ_b=λ_τ$, we compute the rates for lepton flavour violating processes. Experiments in progress or foreseen for $μ\to eγ$, $μ\to e$ conversion (and the dipole moment of the electron) are shown to provide very significant tests of the theory for all slepton masses up to about $1\TeV$.

hep-ph↗

arXiv1992

Radiative Correction Effects of a Very Heavy Top

If the top is very heavy, m_t >> M_Z, the dominant radiative correction effects in all electroweak precision tests can be exactly characterized in terms of two quantities, the rho-parameter and the GIM violating Z -> b bbar coupling. These quantities can be computed using the Standard Model Lagrangian with vanishing gauge couplings. This is done here up to two loops for arbitrary values of the Higgs mass.

hep-ph↗