1,242 research outputs found
Next-to-leading order corrections to gauge-mediated gaugino masses
We compute the next-to-leading order corrections to the gaugino masses in gauge-mediated models for generic values of the messenger masses M and discuss the predictions of unified messenger models. If M<100 TeV there can be up to 10% corrections to the leading order relations . If the messengers are heavier there are only few % corrections. We also study the messenger corrections to gauge coupling unification: as a result of cancellations dictated by supersymmetry, the predicted value of the strong coupling constant is typically only negligibly increased
The golden ratio prediction for the solar neutrino mixing
We present a simple texture that predicts the cotangent of the solar neutrino
mixing angle to be equal to the golden ratio. This prediction is 1.4 standard
deviations below the present best-fit value and final SNO and KamLAND data
could discriminate it from tri-bi-maximal mixing. The neutrino mass matrix is
invariant under a Z_2 x Z'_2 symmetry: that geometrically is a reflection along
the diagonal of the golden rectangle. Assuming an analogous structure in the
quark sector suggests a golden prediction for the Cabibbo angle, theta_C =
pi/4- theta_12 = 13.3 degree, up to uncertainties comparable to V_{ub}.Comment: 5 pages. Final version, to appear on PR
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EU integration in the (post)-migrant-crisis context: learning new integration modes?
This article explores the integration of the European Union (EU) as an institution after the 2015-2016 migrant crisis. Qualitative data from elite interviews in Brussels and policy analysis, in the framework of a bigger project about the impact of the migrant crisis on European integration, highlight the EU learning about new integration modes as a key theme following the crisis. The article focuses on this theme and argues that EU integration has been happening through intensive learning after the-migrant crisis, whereby the EU has been exploring a combination of certain integration modes: shaping the relationships with candidate countries by restraining from enlargement; shaping the relationships with (prospectively) exiting Member States by considering fuzziness at the borders; exploring differentiation among the existing Member States, possibly through promoting a two-tier EU, instead of universal deepening. A key contribution lies in applying the notion âlearningâ to understanding EU integration modes specifically after the migrant crisis
Multi-muon events at the Tevatron: a hidden sector from hadronic collisions
Intrigued by some features of a small but significant fraction of the
multi-muon events recently published by the CDF collaboration, we show an
explicit attempt to describe them in terms of a light scalar singlet
which communicates with the standard quarks either through a heavy scalar or a
heavy fermion exchange. As suggested in arXiv:0810.7530, the singlet has
a chain decay into a final state made of four pairs. We can
simulate most of the muon properties of the selected sample of events. Some of
these properties adhere rather well to the already published data; others
should allow a decisive test of the proposed interpretation. Assuming that the
test is positively passed, we show how the PAMELA excess can be fitted by the
annihilation of a TeV Dark Matter particle that communicates with the Standard
Model via the new light singlet(s).Comment: 19 pp, v2: small changes, agrees with the published versio
Massive and Massless Neutrinos on Unbalanced Seesaws
The observation of neutrino oscillations requires new physics beyond the
standard model (SM). A SM-like gauge theory with p lepton families can be
extended by introducing q heavy right-handed Majorana neutrinos but preserving
its SU(2)_L x U(1)_Y gauge symmetry. The overall neutrino mass matrix M turns
out to be a symmetric (p+q) x (p+q) matrix. Given p>q, the rank of M is in
general equal to 2q, corresponding to 2q non-zero mass eigenvalues. The
existence of (p-q) massless left-handed Majorana neutrinos is an exact
consequence of the model, independent of the usual approximation made in
deriving the Type-I seesaw relation between the effective p x p light Majorana
neutrino mass matrix M_\nu and the q x q heavy Majorana neutrino mass matrix
M_R. In other words, the numbers of massive left- and right-handed neutrinos
are fairly matched. A good example to illustrate this seesaw fair play rule is
the minimal seesaw model with p=3 and q=2, in which one massless neutrino sits
on the unbalanced seesaw.Comment: RevTex 8 pages, 1 PS figure. Two crucial references adde
Anthropic solution to the magnetic muon anomaly: the charged see-saw
We present models of new physics that can explain the muon g-2 anomaly in
accord with with the assumption that the only scalar existing at the weak scale
is the Higgs, as suggested by anthropic selection. Such models are dubbed
"charged see-saw" because the muon mass term is mediated by heavy leptons. The
electroweak contribution to the g-2 gets modified by order one factors, giving
an anomaly of the same order as the observed hint, which is strongly correlated
with a modification of the Higgs coupling to the muon.Comment: 21 pages, many equations despite the first word in the title. v3:
loop function G_WN corrected, conclusions unchange
Parameters' domain in three flavour neutrino oscillations
We consider analytically the domain of the three mixing angles
and the CP phase for three flavour neutrino oscillations both in
vacuum and matter. Similarly to the quark sector, it is necessary and
sufficient to let all the mixing angles
and be in the range and ,
respectively. To exploit the full range of will be important in future
when more precise fits are possible, even without CP violation measurements.
With the above assumption on the angles we can restrict ourselves to the
natural order of masses . Considerations of the mass schemes with
some negative 's, though for some reasons useful, are not necessary
from the point of view of neutrino oscillation parametrization and cause double
counting only. These conclusions are independent of matter effects.Comment: references added, to appear in PL
Muon and Tau Neutrinos Spectra from Solar Flares
Solar neutrino flares and mixing are considered. Most power-full solar flare
as the ones occurred on 23th February 1956, September 29th 1989, 28th October
and on 2nd-4th November 2003 are sources of cosmic rays, X, gamma and neutrino
bursts. These flares took place both on front or in the edge and in the hidden
solar disk. The observed and estimated total flare energy should be a source of
a prompt secondary neutrino burst originated, by proton-proton-pion production
on the sun itself; a more delayed and spread neutrino flux signal arise by the
solar charged flare particles reaching the terrestrial atmosphere. Our first
estimates of neutrino signals in largest underground detectors hint for few
events in correlation with, gamma,radio onser. Our approximated spectra for
muons and taus from these rare solar eruption are shown over the most common
background. The muon and tau signature is very peculiar and characteristic over
electron and anti-electron neutrino fluxes. The rise of muon neutrinos will be
detectable above the minimal muon threshold of 113 MeV. The rarest tau
appearence will be possible only for hardest solar neutrino energies above
3.471 GeVComment: 14 pages, 4 figures, Vulcano Conference 200
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Introduction
The post-2014 'migrant crisis' focusing mainly on the European Union`s southeast periphery where the so called Balkan Route1 exists, has demonstrated that the degree of integration and solidarity among EU members is not as deep and complete as expected. Attempts to outsource the crisis to its periphery impacted also on the relationship of the Union with EU candidate countries. The lack of a common EU policy and reluctance to share sovereignty became evident among EU members from early on. This has in turn led to a demise in the credibility of the EU, its fundamental principles like solidarity among its member states and protection of human rights, as well as, its institutions. The Erasmus+ Jean Monnet project MIGRATE CTRL + Enter Europe â Jean Monnet Migrant Crisis Network2 looks into the developments in the Balkan Route pre and post the EU-Turkey Statement and the responses by the individual countries inside this framework
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