J. Maalampi

Large underground, liquid based detectors for astro-particle physics in Europe: Scientific case and prospects

This document reports on a series of experimental and theoretical studies conducted to assess the astro-particle physics potential of three future large scale particle detectors proposed in Europe as next generation underground observatories. The proposed apparatuses employ three different and, to some extent, complementary detection techniques: GLACIER (liquid argon TPC), LENA (liquid scintillator) and MEMPHYS (water Cherenkov), based on the use of large mass of liquids as active detection media. The results of these studies are presented along with a critical discussion of the performance attainable by the three proposed approaches coupled to existing or planned underground laboratories, in relation to open and outstanding physics issues such as the search for matter instability, the detection of astrophysical neutrinos and geo-neutrinos and to the possible use of these detectors in future high intensity neutrino beams.

Doubly charged Higgs at LHC

Abstract We have investigated the production of doubly charged Higgs particles Δ L , R ++ via the WW fusion process in proton-proton collisions at LHC energies in the framework of the left-right symmetric model. The production cross section of the right-triplet Higgs Δ R ++ is for representative values of the model parameters at femtobarn level. The discovery reach depends on the mass of the right-handed gauge boson W R . At best Δ R ++ masses up to 2.4 TeV are achievable within a one-year run. For Δ L ++ the corresponding limit is 1.75 TeV which depends on the value of the left-triplet vev ν L . Comparison with Drell-Yan pair production processes shows that studies of the WW fusion processes extend the discovery reach of LHC roughly by a factor of two. The main experimental signal of a produced Δ L , R ++ would be a hard same-sign lepton pair. There will be no substantial background due to the Standard Model (SM) interactions, since in the SM a same-sign lepton pair will always be associated with missing energy, i.e. neutrinos, due to lepton number conservation.We have investigated production of doubly charged Higgs particles

Refraction and oscillations of neutrinos in the early universe

\Delta_{L,R}^{++}

Physics of mirror fermions

via WW fusion process in proton-proton collisions at LHC energies in the framework of the left-right symmetric model. The production cross section of the right-triplet Higgs is for representative values of model parameters at femtobarn level. The discovery reach depends on the mass of the right-handed gauge boson W_R. At best

Tree level unitarity and triviality bounds for two-Higgs models☆

\Delta_R^{++}

Resonant neutrino transitions and nucleosynthesis

mass up to 2.4 TeV are achievable within one year run. For

Inert neutrinos is supernovae

\Delta^{++}_L

Non-standard self-interactions of the weak vector bosons and their phenomenological implications

the corresponding limit is 1.75 TeV which depends on the value of the left-triplet vev v_L. Comparison with Drell-Yan pair production processes shows that studies of the WW fusion processes extend the discovery reach of LHC roughly by a factor of two. The main experimental signal of a produced Higgs would be a hard same-sign lepton pair. There will be no substantial background due to the Standard Model (SM) interactions, since in the SM a same-sign lepton pair will always be associated with missing energy, i.e. neutrinos, due to lepton number conservation.

Neutrino Asymmetry and Oscillations in the Early Universe

We have investigated the behaviour of the electron neutrinos νc and antineutrinos νc in the heat bath of the early Universe. We have determined the effective energies of νc and νc as functions of the temperature of the Universe. We assume that νc and νc mix with inert states νx and νinx, respectively, and consider the νc ↔ νx and νc ↔ νx oscillations. We have paid special attention to the adiabaticity and coherence of these transitions and have found that for a large region of the parameter space the system will evolve through a Mikheyev-Smirnov resonance. The numerical study of the combined neutrino and antineutrino systems shows that the dynamical lepton asymmetry is driven to zero. Thus no significant νc t νc asymmetry can be created. If a resonance exists, both neutrinos and antineutrinos will go through it simultaneously. A large conversion of the νc and νc populations in the early Universe into the inert states νx and νx is thus possible.

Cosmic abundances of very heavy neutrinos

Abstract We review the theoretical motivation and phenomenological implications of mirror fermions. Mirror fermions are a new class of particles having V + A weak interactions. They are predicted by many recent particle theories, including orthogonal and unitary symmetries for family unification, Kaluza-Klein theories, extended supersymmetry and composite models. The mass of mirror particles breaks the electroweak symmetry and hence they must be lighter than about 300 GeV. Charged mirror leptons must be heavier than about 27 GeV. Mixing with ordinary quarks and leptons, the mirror fermions would cause violation of the V - A rule in weak interactions. We present an overall fit to experimental data and derive upper bounds for such mixing. We also make a survey of various laboratory experiments, as well as astrophysical and cosmological observations to find constraints for mirror neutrino masses, lifetimes and mixinf angles. We conclude that mirror neutrinos N with masses in the ranges m N ≲ 1 eV and m N ≳ 18 GeV could mix appreciably with ordinary neutrinos. In the ranges 50 MeV ≲ m N ≲ 18 GeV and 1 eV ≲ m N ≲ 25 eV the mixing is 10 −4 -10 −8 or less. Elsewhere mirror neutrinos are forbidden by astrophysical or cosmological arguments. Mirror neutrinos with masses m N ≲ 25 eV or m N ≳ 5 GeV are WIMP candidates; to make them responsible also for the solar neutrino deficiency problem would be rather contrived, however. No limits can be inferred for mirror quarks which must have very small mixing with ordinary quarks. We describe the experimental signatures of and prospects for production of mirror fermions in the new generation of accelerators.