78 research outputs found

### The neutrino ground state in a neutron star

We address a recent claim that the stability of neutron stars implies a lower
bound on the mass of the neutrino. We argue that the result obtained by some
previous authors is due to an improper summation of an infrared-sensitive
series and that a non-perturbative "resummation" of the series yields a finite
and well-behaved result. The stability of neutron stars thus gives no lower
bound on the mass of the neutrino.Comment: 5 pages, 3 figures, Latex (uses espcrc2.sty); contribution to the
proceedings of Neutrino 98, Takayama, Japan, 4-9 June, 199

### Detecting New Physics in Rare Top Decays at the LHC

In the companion paper it was shown that there are six observables in $gg\to
t \bar t \to (b \bar b c) (\bar b \ell \bar \nu)$ that can be used to reveal
the presence of new physics (NP) in $t \to b \bar b c$. In the present paper we
examine the prospects for detecting and identifying such NP at the LHC, in both
the short term and long term. To this end, we develop an algorithm for
extracting the NP parameters from measurements of the observables. In the short
term, depending on what measurements have been made, there are several
different ways of detecting the presence of NP. It may even be possible to
approximately determine the values of certain NP parameters. In the long term,
it is expected that all six observables will be measured. The values of the NP
parameters can then be determined reasonably precisely from a fit to these
measurements, which will provide good information about the type of NP present
in $t \to b \bar b c$.Comment: Published versio

### Disentangling the Seesaw in the Left-Right Model -- An Algorithm for the General Case

Senjanovic and Tello have analyzed how one could determine the neutrino Dirac
mass matrix in the minimal left-right model, assuming that the mass matrices
for the light and heavy neutrinos could be taken as inputs. They have provided
an analytical solution for the Dirac mass matrix in the case that the
left-right symmetry is implemented via a generalized parity symmetry and that
this symmetry remains unbroken in the Dirac Yukawa sector. We extend the work
of Senjanovic and Tello to the case in which the generalized parity symmetry is
broken in the Dirac Yukawa sector. In this case the elegant method outlined by
Senjanovic and Tello breaks down and we need to adopt a numerical approach.
Several iterative approaches are described; these are found to work in some
cases but to be highly unstable in others. A stable, prescriptive numerical
algorithm is described that works in all but a vanishingly small number of
cases. We apply this algorithm to numerical data sets that are consistent with
current experimental constraints on neutrino masses and mixings. We also
provide some additional context and supporting explanations for the case in
which the parity symmetry is unbroken.Comment: 34 pages, 4 figures; published versio

### Higgs Sector of the Left-Right Model with Explicit CP Violation

We explore the Higgs sector of the Minimal Left-Right (LR) Model based on the
gauge group SU(2)_L x SU(2)_R x U(1)_{B-L} with explicit CP violation in the
Higgs potential. Since flavour-changing neutral current experiments and the
small scale of neutrino masses both place stringent constraints on the Higgs
potential, we seek to determine whether minima of the Higgs potential exist
that are consistent with current experimental bounds. We focus on the case in
which the right-handed symmetry-breaking scale is only ``moderately'' large, of
order 15-50 TeV. Unlike the case in which the Higgs potential is CP-invariant,
the CP noninvariant case does yield viable scenarios, although these require a
small amount of fine-tuning. We consider a LR model supplemented by an
additional U(1) horizontal symmetry, which results in a Higgs sector consistent
with current experimental constraints and a realistic spectrum of neutrino
masses.Comment: 20 pages, 2 figure

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