49 research outputs found
New Physics in : Interplay between semileptonic kaon and hyperon decays
We review a novel model-independent approach to the analysis of new-physics
effects in the transitions. We apply it to (semi)leptonic
kaon decays and study their complementarity with pion and hyperon
decays or with collider searches of new physics.Comment: Contribution to the NA62 Physics Handbook. It summarizes the analysis
presented in arXiv:1605.07114 and discusses in more detail the interplay
between and semileptonic hyperon decays as new-physics probe
decay anomalies from nonabelian local horizontal symmetry
Recent anomalies in meson decays are consistent with
exchange of a heavy vector boson. Here we try to connect such new physics
to understanding the origin of flavor, by gauging generation number.
Phenomenological and theoretical considerations suggest that the smallest
viable flavor symmetry (not including any extra U(1) factors) is chiral , which acts only on generation indices and does
not distinguish between quarks and leptons. Spontaneous breaking of the
symmetry gives rise to the standard model Yukawa matrices, and masses for the
16 -like gauge bosons, one of which is presumed to be light enough to
explain the anomalies. We perform a bottom-up study of
this framework, showing that it is highly constrained by LHC dilepton searches,
meson mixing, decays and CKM unitarity. Similar anomalies are predicted for
semileptonic decays of to lighter mesons, with excesses in the
channels and deficits in , but no deviation in .
The lightest mass is TeV if the gauge coupling is .Comment: 13 pages, 4 figures; v2: minor corrections and improvements,
references added; v3: corrected fig.1, published versio
Non-standard semileptonic hyperon decays
We investigate the discovery potential of semileptonic hyperon decays in
terms of searches of new physics at teraelectronvolt scales. These decays are
controlled by a small -flavor breaking parameter that allows for
systematic expansions and accurate predictions in terms of a reduced dependence
on hadronic form factors. We find that muonic modes are very sensitive to
non-standard scalar and tensor contributions and demonstrate that these could
provide a powerful synergy with direct searches of new physics at the LHC.Comment: v2. Comparison with direct searches of new physics at the LHC
presente
Supernova constraints on dark flavored sectors
Proto-neutron stars forming a few seconds after core-collapse supernovae are hot and dense environments where hyperons can be efficiently produced by weak processes. By making use of various state-of-the-art supernova simulations combined with the proper extensions of the equations of state including Î hyperons, we calculate the cooling of the star induced by the emission of dark particles X0 through the decay Î â nX0. Comparing this novel energy-loss process to the neutrino cooling of SN 1987A allows us to set a stringent upper limit on the branching fraction, BR(Î â nX0 ) †8 Ă 10â9, that we apply to massless dark photons and axions with flavor-violating couplings to quarks. We find that the new supernova bound can be orders of magnitude stronger than other limits in dark-sector models.publishedVersio
Confronting fuzzy dark matter with the rotation curves of nearby dwarf irregular galaxies
We investigate phenomenologically the viability of fuzzy dark matter (FDM).
We do this by confronting the predictions of the model, in particular, the
formation of a solitonic core at the center of dark matter halos, with a
homogeneous and robust sample of high-resolution rotation curves from the
''LITTLE THINGS in 3D'' catalog. This comprises a collection of isolated, dark
matter dominated dwarf-irregular galaxies that provides an optimal benchmark
for cosmological studies. We use a statistical framework based on Markov chain
Monte Carlo techniques that allows us to extract relevant parameters such as
the axion mass, the mass of the solitonic core, the mass of the dark matter
halo and its concentration parameter with a rather loose set of priors except
for the implementation of a core-halo relation that is predicted by
simulations. The results of the fits are used to perform various diagnostics on
the predictions of the model. FDM provides an excellent fit to the rotation
curves of the ''LITTLE THINGS in 3D'' catalog, with axion masses determined
from different galaxies clustering around eV.
However, we find two major problems in our analysis. First, the data follow
scaling relations of the properties of the core which are not consistent with
the predictions of the soliton. This problem is particularly acute in the core
radius - mass relation with a tension that, at face value, has a significance
. The second problem is related to the strong suppression of
the linear power spectrum that is predicted by FDM for the axion mass preferred
by the data. This can be constrained very conservatively by the galaxy counts
in our sample, which leads to a tension exceeding again . We estimate
the effects of baryons in our analysis and discuss whether they could alleviate
the tensions of the model with observations.Comment: 22 pages, 9 figures, 3 table
The Mono-Tau Menace: From Decays to High- Tails
We investigate the crossing-symmetry relation between
decay and scattering to derive direct correlations
of New Physics in semi-tauonic -meson decays and the mono-tau signature at
the LHC ( + MET). Using an exhaustive set of effective operators
and heavy mediators we find that the current ATLAS and CMS data constrain
scenarios addressing anomalies in -decays. Pure tensor solutions, completed
by leptoquark, and right-handed solutions, completed by or
leptoquark, are challenged by our analysis. Furthermore, the sensitivity that
will be achieved in the high-luminosity phase of the LHC will probe the
possible scenarios that explain the anomalies. Finally, we note that the LHC is
also competitive in the transitions and bounds in some cases are
currently better than those from decays.Comment: No comment