327 research outputs found
Interpreting the 750 GeV digamma excess: a review
We summarise the main experimental, phenomenological and theoretical issues
related to the 750 GeV digamma excessComment: To appear in the proceedings of the Moriond 2016 conference. Version
2: note added, it's dea
Sommerfeld corrections to type-II and III leptogenesis
We study thermal leptogenesis from decays of the electroweak triplets that
mediate neutrino masses in type-II and type-III see-saw. We find that
Sommerfeld corrections reduce the baryon asymmetry by ~30%, and that successful
leptogenesis needs triplets heavier than 1.6 TeV, beyond the discovery reach of
LHC.Comment: 12 pages, 4 figures, final version. The group theory of the
non-abelian Sommerfeld effect presented in this paper can be relevant for
scenarios of Dark Matter charged under new dark gauge groups, as suggested by
recent dat
Distinguishing gauge-mediated from unified-supergravity spectra
We show that gauge-mediation and unified-supergravity give sufficiently firm
and different predictions for the spectrum of supersymmetric particles to make
it possible to discriminate the two scenarios even if the messenger mass is
close to the unification scale.Comment: 6 page
Naturalness of supersymmetric models
After presenting a simple procedure for testing naturalness (similar to
Bayesian inference and not more subjective than it) we show that LEP2
experiments pose a naturalness problem for `conventional' supersymmetric
models. About 95% of the parameter space of minimal supergravity MSSM is
excluded by LEP2 experiments. Moreover in this model electroweak baryogenesis,
or detectable supersymmetric corrections to mixing of K and B mesons, are
possible only in very small corners of the parameter space. The naturalness
problem is stronger in gauge mediation models, expecially with light
messengers. We recall some possible explanations (different from an improbable
numerical accident) of why supersymmetry has not (yet?) been found.Comment: from a talk presented at Moriond 99. This paper is mainly a brief
discussion of hep-ph/9811386, with only few original point
Implications of first LHC results
We discuss implications of first LHC results for models motivated by the
hierarchy problem: large extra dimensions and supersymmetry. We present bounds,
global fits and implications for naturalness.Comment: Talk at Moriond 2011. Updated to latest data (up to 165/pb
Radiatively induced light right-handed stop
A right-handed stop not much heavier or even lighter than the Z boson has
today desirable phenomenological consequences. We study how it can result
within the usual radiative scenario of electroweak symmetry breaking. A
restriction on the gaugino mass parameters, M_2 < 0.3 m_10, arises if soft
terms satisfy relations suggested by unification theories. Moreover, requiring
to get a light stop without unnatural fine-tunings below the per-cent level, we
obtain another more interesting upper bound on the chargino mass, M_chargino <
M_Z, and we derive interesting conclusions about the masses of the gluino, M_3
\sim (150-300) GeV, of the heavy stop, M_stop \sim (250-500) GeV, and of the
left/right mixing angle in the stop sector, |\theta_stop| < 0.3.Comment: 4 pages, figures included, one reference added. PS-file also
available at http://www.ft.uam.es/~strumia/15Art/15Art2.p
Which solar neutrino experiment after KamLAND and Borexino?
We estimate how well we will know the parameters of solar neutrino
oscillations after KamLAND and Borexino. The expected error on Delta m^2 is few
per-mille in the VO and QVO regions, few per-cent in the LMA region, and around
10% in the LOW region. The expected error on sin^2 2theta is around 5%. KamLAND
and Borexino will tell unambiguously which specific new measurement, dedicated
to pp solar neutrinos, is able to contribute to the determination of theta and
perhaps of Delta m^2. The present data suggest as more likely outcomes: no
measurement, or the total pp rate, or its day/night variation.Comment: 12 pages, 4 figures. v2: comments and references added, final versio
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