26 research outputs found
Intertwinors on Functions over the Product of Spheres
We give explicit formulas for the intertwinors on the scalar functions over
the product of spheres with the natural pseudo-Riemannian product metric using
the spectrum generating technique. As a consequence, this provides another
proof of the even order conformally invariant differential operator formulas
obtained earlier by T. Branson and the present author
Translation to Bundle Operators
We give explicit formulas for conformally invariant operators with leading
term an -th power of Laplacian on the product of spheres with the natural
pseudo-Riemannian product metric for all .Comment: This is a contribution to the Proceedings of the 2007 Midwest
Geometry Conference in honor of Thomas P. Branson, published in SIGMA
(Symmetry, Integrability and Geometry: Methods and Applications) at
http://www.emis.de/journals/SIGMA
LHC Signals from Cascade Decays of Warped Vector Resonances
Recently (arXiv:1608.00526), a new framework for warped higher-dimensional
compactifications with "bulk" standard model (SM) was proposed: in addition to
the UV (Planck scale) and IR (a couple of TeV) branes, there is an intermediate
brane, taken to be around 10 TeV. The SM matter and Higgs fields propagate from
the UV brane down to this intermediate brane only, while gauge and gravity
fields propagate in the entire bulk. Such a configuration renders the lightest
gauge Kaluza-Klein (KK) states within LHC reach, simultaneously satisfying
flavor and CP constraints. In addition, the usual leading decay modes of the
lightest KK gauge bosons into top and Higgs bosons are suppressed. This effect
permits erstwhile subdominant channels to become significant. These include
flavor-universal decays to SM fermions and Higgs bosons, and a novel channel -
decay to a radion and a SM gauge boson, followed by radion decay to a pair of
SM gauge bosons. In this work, we first delineate the parameter space where the
above mentioned cascade decay of gauge KK particles dominates, and thereby can
be the discovery mode at the LHC. We then perform a detailed analysis of the
LHC signals from this model, finding that 300/fb suffices for evidence of
KK-gluon in tri-jet, jet + di-photon and jet + di-boson channels. However, KK
photon in photon + di-jet, and KK-W in leptonic W + di-jet require 3000/fb. The
crucial feature of this decay chain is a "double" resonance, i.e. 3-particle
and 2-particle invariant mass peaks, corresponding to the KK gauge boson and
the radion respectively.Comment: 50 page
Detecting a Boosted Diboson Resonance
New light scalar particles in the mass range of hundreds of GeV, decaying
into a pair of bosons can appear in several extensions of the SM. The
focus of collider studies for such a scalar is often on its direct production,
where the scalar is typically only mildly boosted. The observed are
therefore well-separated, allowing analyses for the scalar resonance in a
standard fashion as a low-mass diboson resonance. In this work we instead focus
on the scenario where the direct production of the scalar is suppressed, and it
is rather produced via the decay of a significantly heavier (a few TeV mass)
new particle, in conjunction with SM particles. Such a process results in the
scalar being highly boosted, rendering the 's from its decay merged. The
final state in such a decay is a "fat" jet, which can be either four-pronged
(for fully hadronic decays), or may be like a jet, but with leptons
buried inside (if one of the decays leptonically). In addition, this fat
jet has a jet mass that can be quite different from that of the /Higgs/top
quark-induced jet, and may be missed by existing searches. In this work, we
develop dedicated algorithms for tagging such multi-layered "boosted dibosons"
at the LHC. As a concrete application, we discuss an extension of the standard
warped extra-dimensional framework where such a light scalar can arise. We
demonstrate that the use of these algorithms gives sensitivity in mass ranges
that are otherwise poorly constrained.Comment: 33 pages, 13 figure
Dedicated Strategies for Triboson Signals from Cascade Decays of Vector Resonances
New colorless electroweak (EW) charged spin-1 particles with mass of a few
TeV arise in numerous extensions of the Standard Model (SM). Decays of such a
vector into a pair of SM particles, either fermions or EW bosons, are well
studied. Many of these models have an additional scalar, which can lead to (and
even dominate in certain parameter regions) a novel decay channel for the heavy
vector particles instead - into a SM EW boson and the scalar, which
subsequently decays into a SM EW boson pair. In this work, we focus on the
scalar being relatively heavy, roughly factor of two lighter than the vector
particles, rendering its decay products well separated. Such a cascade decay
results in a final state with three isolated bosons. We argue that for this
"triboson" signal the existing diboson searches are not quite optimal due to
combinatorial ambiguity for three identical bosons, and in addition, due to a
relatively small signal cross-section determined by the heaviness of the
decaying vector particle. In order to isolate the signal, we demonstrate that
tagging all three bosons, followed by use of the full triboson invariant mass
distribution as well as that of appropriate subsets of dibosons, is well
motivated. We develop these general strategies in detail within the context of
a specific class of models that are based on extensions of the standard warped
extra-dimensional scenario. We also point out that a similar analysis would
apply to models with an enlarged EW gauge sector in four dimensions, even if
they involve a different Lorentz structure for the relevant couplings
Spectrum generating on twistor bundle
summary:Spectrum generating technique introduced by Ólafsson, Ørsted, and one of the authors in the paper (Branson, T., Ólafsson, G. and Ørsted, B., Spectrum generating operators, and intertwining operators for representations induced from a maximal parabolic subgroups, J. Funct. Anal. 135 (1996), 163–205.) provides an efficient way to construct certain intertwinors when -types are of multiplicity at most one. Intertwinors on the twistor bundle over have some -types of multiplicity 2. With some additional calculation along with the spectrum generating technique, we give explicit formulas for these intertwinors of all orders