20 research outputs found
Gluon vs. Photon Production of a 750 GeV Diphoton Resonance
The production mechanism of a 750 GeV diphoton resonance, either via gluon or
photon fusion, can be probed by studying kinematic observables in the diphoton
events. We perform a detector study of the two production modes of a
hypothetical scalar or tensor diphoton resonance in order to characterize the
features of the two scenarios. The nature of the resonance production can be
determined from the jet multiplicity, the jet and diphoton rapidities, the rate
of central pseudorapidity gaps, or the possible detection of forward protons
from elastic photoproduction for events in the signal region. Kinematic
distributions for both signals and expected irreducible diphoton background
events are provided for comparison along with a study of observables useful for
distinguishing the two scenarios at an integrated luminosity of 20 fb.
We find that decay photons from a 750 GeV scalar resonance have a preference
for acceptance in the central detector barrel, while background events are more
likely to give accepted photons in the detector end caps. This disfavors the
interpretation of the large number of excess events found by the the Run-2 CMS
diphoton search with one photon detected in the end cap as a wide spin-0
resonance signal. However, one expects more end cap photons in the case of
spin-2 resonance.Comment: 14 pages, 15 figure
Phenomenology of a Long-Lived LSP with R-Parity Violation
We present the leading experimental constraints on supersymmetric models with
R-parity violation (RPV) and a long-lived lightest superpartner (LSP). We
consider both the well-motivated dynamical RPV scenario as well as the
conventional holomorphic RPV operators. Guided by naturalness, we study the
cases of stop, gluino, and higgsino LSPs with several possible leading decay
channels in each case. The CMS displaced dijet and the ATLAS multitrack
displaced vertex searches have been fully recast, with all cuts and vertex
reconstruction algorithms applied. Heavy charged stable particle searches by
CMS are also applied. In addition, we consider representative bounds for prompt
LSP decays that are directly applicable. Our main results are exclusion plots
in the plane for the various scenarios. We find
that the natural parameter space ( GeV,
GeV, GeV) is excluded for a long-lived
LSP ( mm).Comment: 25 pages, 8 figure
Continuum Naturalness
We present a novel class of composite Higgs models in which the top and gauge
partners responsible for cutting off the Higgs quadratic divergences form a
continuum. The continuum states are characterized by their spectral densities,
which should have a finite gap for realistic models. We present a concrete
example based on a warped extra dimension with a linear dilaton, where this
finite gap appears naturally. We derive the spectral densities in this model
and calculate the full Higgs potential for a phenomenologically viable
benchmark point, with percent level tuning. The continuum top and gauge
partners in this model evade all resonance searches at the LHC and yield
qualitatively different collider signals