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Search Results: 1 - 10 of 297585 matches for " J. Maalampi "
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WW$γ$ and WWZ Production in $e^-e^-$ Collisions in the Left-Right Model
A. Pietil?,J. Maalampi
Physics , 1995, DOI: 10.1103/PhysRevD.52.1386
Abstract: We have investigated the three vector boson production in electron-electron collisions in the framework of the left-right symmetric electroweak model. The process occurs due to lepton number violating interactions mediated by Majorana neutrinos and triplet Higgs scalars. We find that only the reactions with a heavy gauge boson pair in the final state, $e^-e^-\to W^{-}_2 W^{-}_2\gamma$ and $e^-e^- \to W^{-}_2 W^{-}_2Z^0_1$, are phenomenologically interesting from the point of view of the Next Linear Collider. If the mass of $W_2^-$ is 0.5 TeV and the mass of the heavy Majorana neutrino of the order of 1 TeV, the cross section of both reactions is in the range 1 to 10 fb at $\sqrt{s}= 2$ TeV, depending on the mass of the doubly charged triplet Higgs $\delta^{--}$, yielding a 1 % background for the pair production of $W_2^-$. At the $\delta^{--}$ resonance the cross section can be as large as 1 pb.
Phenomenological Determination of the Beauty Meson Decay Parameter $f_B$ and the CP-Violating Angle $δ$
J. Maalampi,M. Roos
Physics , 1994, DOI: 10.1007/BF01553985
Abstract: We fit the ${\cal CKM}$-matrix to all recent data with the following free parameters: three mixing angles, the CP-violating angle $\delta$ in the Maiani parametrisation, the top quark mass $m_t$, and the product $f_B{\cal B}_{\B}^{1/2}$, where $f_B$ is the $B$-meson decay parameter and ${\cal B}_{\B}$ is the bag parameter. Our fits span a contiguous region in the $(f_B{\cal B}_{\B}^{1/2},\ \cos\delta)$--plane, limited by $0.117\lsim f_B{\cal B}_{\B}^{1/2}/{\rm GeV}\lsim 0.231$ and --0.95 $\lsim$ $\cos\delta$ $\lsim$ 0.70. The parameters $f_B{\cal B}_{\B}^{1/2}$ and $\cos\delta$ are strongly positively correlated.
Production of qqQQ final states in ee collisions in the left-right symmetric model
J. Maalampi,N. Romanenko
Physics , 1998, DOI: 10.1103/PhysRevD.60.055002
Abstract: We consider the reaction ee ->qqQQ as a test of lepton number non-conservation in the framework of the left-right-symmetric electroweak model. The main contributions to this process are due to Majorana neutrino exchange in t-channel and doubly charged Higgs (Delta{--}) exchange in s-channel with a pair of right-handed weak bosons (WR) as intermediate state. We show that in a linear ee collider with the collision energy of 1 TeV (1.5 TeV) the cross section of this process is 0.01 fb (1 fb), and it will, for the anticipated luminosity of 10**{35} cm**{-2}, be detectable below the WR threshold. We study the sensitivity of the reaction on the masses of the heavy neutrino, WR and Delta{--}.
Testing neutrino instability with active galactic nuclei
P. Keranen,J. Maalampi,J. T. Peltoniemi
Physics , 1999, DOI: 10.1016/S0370-2693(99)00862-X
Abstract: Active galactic nuclei and gamma ray bursts at cosmological distances are sources of high-energy electron and muon neutrinos and provide a unique test bench for neutrino instability. The typical lifetime-to-mass ratio one can reach there is $\tau/m\sim 500 Mpc/cE_{\nu}\sim 500$ s/eV. We study the rapid decay channel $\nu_i\to\nu_j+\phi$, where $\phi$ is a massless or very light scalar (possibly a Goldstone boson), and point out that one can test the coupling strength of $g_{ij}\nu_i\nu_j$ down to $g_{ij}\lsim 10^{-8} eV/m$ by measuring the relative fluxes of $\nu_{e}$, $\nu_{\mu}$ and $\nu_{\tau}$. This is orders of magnitude more stringent bound than what one can obtain in other phenomena, e.g. in neutrinoless double beta decay with scalar emission.
Baryon and lepton number transport in electroweak phase transition
J. Maalampi,J. Sirkka,I. Vilja
Physics , 1994, DOI: 10.1016/0370-2693(94)91454-0
Abstract: We consider the baryon number generation by charge transport mechanism in the electroweak phase transition taking properly into account thermal fluxes through the wall separating true and false vacuum in the spatial space. We show that the diffusion from the true vacuum to the false one has a large diminishing effect on the baryon number unless the wall velocity is near to, but less than, the speed of sound in the medium and the ratio between the collision rate and wall thickness is about 0.3. The maximum net baryon density generated is $\rho_B/s\simeq 0.2\times 10^{-10}$, where $s$ is the entropy density of the Universe. If the wall proceeds as a detonation, no baryon number is produced.
The $W_R$ production in $eγ$ collisions
K. Huitu,J. Maalampi,M. Raidal
Physics , 1995, DOI: 10.1016/0370-2693(95)01291-5
Abstract: We consider the production of a single right-handed gauge boson $W_R$ in the high-energy $e^-\gamma$ collisions with polarized beams. If the associated neutrino is light, the reaction will give the best discovery reach for $W_R$ in the Next Linear Collider.
Supersymmetric Left-Right Model and its Tests in Linear Colliders
K. Huitu,J. Maalampi,M. Raidal
Physics , 1993, DOI: 10.1016/0550-3213(94)90073-6
Abstract: We investigate phenomenological implications of a supersymmetric left-right model based on $SU(2)_L\times SU(2)_R\times U(1)_{B-L}\,$ gauge symmetry testable in the next generation linear colliders. We concentrate in particular on the doubly charged $SU(2)_R$ triplet higgsino $\tilde\Delta$, which we find very suitable for experimental search. We estimate its production rate in $e^+e^-$, $e^-e^-$, $e^-\gamma$ and $\gamma\gamma$ collisions and consider its subsequent decays. These processes have a clear discovery signature with a very low background from other processes.
Phenomenological implications of supersymmetry in left-right electroweak model.
K. Huitu,J. Maalampi,M. Raidal
Physics , 1995,
Abstract: The basics of a supersymmetric left-right model are reviewed. The production and subsequent decays of the doubly charged triplet higgsino $ \tilde\Delta^{\pm\pm}$ in the Next Linear Collider are discussed. The slepton pair production in the framework of this model is also analysed.
Supersymmetric Left-Right Model and its Phenomenological Implications
K. Huitu,J. Maalampi,M. Raidal
Physics , 1994,
Abstract: We review here our study of a supersymmetric left-right model (SLRM). In the model the $R$-parity is spontaneously broken. Phenomenologically novel feature of the model is the occurrance of the doubly charged particles in the Higgs sector, which are possibly light enough to be seen in the next linear collider. Detection of the doubly charged higgsinos in the next linear collider is discussed.
Slepton pair production in e+e- collision in supersymmetric left-right model
K. Huitu,J. Maalampi,M. Raidal
Physics , 1994, DOI: 10.1016/0370-2693(94)90428-6
Abstract: The pair production of sleptons in electron-positron collisions is investigated in a supersymmetric left-right model. The cross section is found considerably larger than in the minimal supersymmetric version of the Standard Model (MSSM) because of more contributing graphs. A novel process is a doubly charged higgsino exchange in u-channel, which makes the angular distribution of the final state particles and the final state asymmetries to differ from those of the MSSM. It also allows for the flavour non-diagonal final states $\tilde e\tilde\mu$, $\tilde e\tilde\tau$ and $\tilde \mu\tilde\tau$, forbidden in the MSSM. These processes also give indirect information about neutrino mixings since they depend on the same couplings as the Majorana mass terms of the right-handed neutrinos.
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