144 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
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
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
The baryon-decuplet in the chiral dynamics of Lambda-hyperons in nuclear matter
We study the long range part of the -hyperon optical potential in
nuclei using Quantum Many Body techniques and flavor-SU(3) Chiral Lagrangians
as starting point. More precisely, we study the contributions to the
-hyperon optical potential due to the long-range two-pion exchange,
with and baryons in the internal baryonic lines and
considering Nh and h excitations. We also consider the contribution to
the spin-orbit potentials that comes out from these terms. Our results support
a natural explanation of the smallness of the -nuclear spin-orbit
interaction and shows the importance of the and degrees of
freedom for the hyperon-nucleus interactions.Comment: 8 pages, 5 figure
Electromagnetic properties of baryons
We discuss the chiral behavior of nucleon and Delta(1232) electromagnetic
properties within the framework of a SU(2) covariant baryon chiral perturbation
theory. Our one-loop calculation is complete to the order p^3 and p^4/Delta
with Delta as the Delta(1232)-nucleon energy gap. We show that the magnetic
moment of a resonance can be defined through the linear energy shift only when
an additional relation between the involved masses and the applied magnetic
field strength is fulfilled. Singularities and cusps in the pion mass
dependence of the Delta(1232) electromagnetic moments reflect a
non-fulfillment. We show results for the pion mass dependence of the nucleon
iso-vector electromagnetic quantities and present results for finite volume
effects on the iso-vector anomalous magnetic moment.Comment: 4 pages, 3 figures, prepared for Proceedings of the International
Conference on the Structure of Baryons (BARYONS'10), Osaka, Japan, Dec. 7-11,
201
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