360 research outputs found
Anomalous Neutrino Interaction, Muon g-2, and Atomic Parity Nonconservation
We propose a simple unified description of two recent precision measurements
which suggest new physics beyond the Standard Model of particle interactions,
i.e. the deviation of in deep inelastic neutrino-nucleon
scattering and that of the anomalous magnetic moment of the muon. Our proposal
is also consistent with a third precision measurement, i.e. that of parity
nonconservation in atomic Cesium, which agrees with the Standard Model.Comment: 9 pages, including 1 figure, latest muon g-2 information adde
Searching for energetic cosmic axions in a laboratory experiment: testing the PVLAS anomaly
Astrophysical sources of energetic gamma rays provide the right conditions
for maximal mixing between (pseudo)scalar (axion-like) particles and photons if
their coupling is as strong as suggested by the PVLAS claim. This is
independent of whether or not the axion interaction is standard at all energies
or becomes supressed in the extreme conditions of the stellar interior. The
flux of such particles through the Earth could be observed using a metre long,
Tesla strength superconducting solenoid thus testing the axion interpretation
of the PVLAS anomaly. The rate of events in CAST caused by axions from the Crab
pulsar is also estimated for the PVLAS-favoured parameters.Comment: 5 pages, 3 figur
TeV-scale bileptons, see-saw type II and lepton flavor violation in core-collapse supernova
Electrons and electron neutrinos in the inner core of the core-collapse
supernova are highly degenerate and therefore numerous during a few seconds of
explosion. In contrast, leptons of other flavors are non-degenerate and
therefore relatively scarce. This is due to lepton flavor conservation. If this
conservation law is broken by some non-standard interactions, electron
neutrinos are converted to muon and tau-neutrinos, and electrons - to muons.
This affects the supernova dynamics and the supernova neutrino signal. We
consider lepton flavor violating interactions mediated by scalar bileptons,
i.e. heavy scalars with lepton number 2. It is shown that in case of TeV-mass
bileptons the electron fermi gas is equilibrated with non-electron species
inside the inner supernova core at a time-scale of order of (1-100) ms. In
particular, a scalar triplet which generates neutrino masses through the
see-saw type II mechanism is considered. It is found that supernova core is
sensitive to yet unprobed values of masses and couplings of the triplet.Comment: accepted to Eur.Phys.J.
The Majorana neutrino masses, neutrinoless double beta decay and nuclear matrix elements
The effective Majorana neutrino mass is evaluated by using the latest results
of neutrino oscillation experiments. The problems of the neutrino mass
spectrum,absolute mass scale of neutrinos and the effect of CP phases are
addressed. A connection to the next generation of the neutrinoless double beta
decay (0nbb-decay) experiments is discussed. The calculations are performed for
76Ge, 100Mo, 136Xe and 130Te by using the advantage of recently evaluated
nuclear matrix elements with significantly reduced theoretical uncertainty. An
importance of observation of the 0nbb-decay of several nuclei is stressed.Comment: 29 pages, 5 figures, EXO (10 t) experiment considere
More about neutron - mirror neutron oscillation
It was pointed out recently that oscillation of the neutron into mirror
neutron , a sterile twin of the neutron with exactly the same mass, could
be a very fast process with the the baryon number violation, even faster than
the neutron decay itself. This process is sensitive to the magnetic fields and
it could be observed by comparing the neutron lose rates in the UCN storage
chambers for different magnetic backgrounds. We calculate the probability of
oscillation in the case when a mirror magnetic field is
non-zero and show that in this case it can be suppressed or resonantly enhanced
by applying the ordinary magnetic field , depending on its strength
and on its orientation with respect to . The recent experimental
data, under this hypothesis, still allow the oscillation time order 1 s
or even smaller. Moreover, they indicate that the neutron losses are sensitive
to the orientation of the magnetic field. %at about level. If these
hints will be confirmed in the future experiments, this would point to the
presence of the mirror magnetic field on the Earth of the order of 0.1 G, or
some equivalent spin-dependent force of the other origin that makes a
difference between the neutron and mirror neutron states.Comment: 10 page
Search for heavy neutrinos mixing with tau neutrinos
We report on a search for heavy neutrinos (\nus) produced in the decay
D_s\to \tau \nus at the SPS proton target followed by the decay \nudecay in
the NOMAD detector. Both decays are expected to occur if \nus is a component
of .\
From the analysis of the data collected during the 1996-1998 runs with
protons on target, a single candidate event consistent with
background expectations was found. This allows to derive an upper limit on the
mixing strength between the heavy neutrino and the tau neutrino in the \nus
mass range from 10 to 190 . Windows between the SN1987a and Big Bang
Nucleosynthesis lower limits and our result are still open for future
experimental searches. The results obtained are used to constrain an
interpretation of the time anomaly observed in the KARMEN1 detector.\Comment: 20 pages, 7 figures, a few comments adde
Search for Doubly-Charged Higgs Bosons at LEP
Doubly-charged Higgs bosons are searched for in e^+e^- collision data
collected with the L3 detector at LEP at centre-of-mass energies up to 209 GeV.
Final states with four leptons are analysed to tag the pair-production of
doubly charged Higgs bosons. No significant excess is found and lower limits at
95% confidence level on the doubly-charged Higgs boson mass are derived. They
vary from 95.5 GeV to 100.2 GeV, depending on the decay mode. Doubly-charged
Higgs bosons which couple to electrons would modify the cross section and
forward-backward asymmetry of the e^+e^- -> e^+e^- process. The measurements of
these quantities do not deviate from the Standard Model expectations and
doubly-charged Higgs bosons with masses up to the order of a TeV are excluded
Explaining through the synthesis of ordinary matter from mirror matter: a more general analysis
The emerging cosmological picture is of a spatially flat universe composed
predominantly of three components: ordinary baryons (),
non-baryonic dark matter () and dark energy
(). We recently proposed that ordinary matter was
synthesised from mirror matter, motivated by the argument that the observed
similarity of and suggests an underlying similarity
between the fundamental properties of ordinary and dark matter particles. In
this paper we generalise the previous analysis by considering a wider class of
effective operators that non-gravitationally couple the ordinary and mirror
sectors. We find that while all considered operators imply
few, only a subset quantitatively reproduce the observed ratio
. The eV mass scale induced
through these operators hints at a connection with neutrino oscillation
physics.Comment: minor changes, some references added, about 10 page
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