55 research outputs found
A Physics Show Performed by Students for Kids: From Mechanics to Elementary Particle Physics
We describe an initiative at the University of Bonn, where the students
develop and perform a 2 hour physics show for school classes and the general
public. The show is entertaining and educational and is aimed at children aged
10 and older. For the physics students this is a unique experience to apply
their knowledge at an early stage and gives them the chance to develop skills
in the public presentation of science, in front of 520 people per show. We have
extended the activity to put on an elementary particle physics show for
teenagers. Furthermore, local high schools have picked up the idea; their
students put on similar shows for fellow students and parents. We would be
interested in hearing about related activities elsewhere.Comment: 6 Pages, LateX, 3 Figures. High quality figures available from
author. Journal submission notice adde
Rapidity Gap Events for Squark Pair Production at the LHC
The exchange of electroweak gauginos in the or channel allows squark
pair production at hadron colliders without color exchange between the squarks.
This can give rise to events where little or no energy is deposited in the
detector between the squark decay products. We discuss the potential for
detection of such rapidity gap events at the Large Hadron Collider (LHC). We
present an analysis with full event simulation using PYTHIA as well as
Herwig++, but without detector simulation. We analyze the transverse energy
deposited between the jets from squark decay, as well as the probability of
finding a third jet in between the two hardest jets. For the mSUGRA benchmark
point SPS1a we find statistically significant evidence for a color singlet
exchange contribution.Comment: 4 pages, 2 figures. To be published in the proceedings of SUSY09,
Northeastern University, Boston, M
Supernova Constraints on MeV Dark Sectors from e+ e- Annihilations
Theories with dark forces and dark sectors are of interest for dark matter
models. In this paper we find the region in parameter space that is constrained
by supernova cooling constraints when the models include dark sector particles
with masses around 100 MeV or less. We include only interactions with electrons
and positrons. The constraint is important for small mixing parameters.Comment: 18 pages, 3 figure
White Dwarfs constrain Dark Forces
The white dwarf luminosity function, which provides information about their
cooling, has been measured with high precision in the past few years.
Simulations that include well known Standard Model physics give a good fit to
the data. This leaves little room for new physics and makes these astrophysical
objects a good laboratory for testing models beyond the Standard Model. It has
already been suggested that white dwarfs might provide some evidence for the
existence of axions. In this work we study the constraints that the white dwarf
luminosity function puts on physics beyond the Standard Model involving new
light particles (fermions or bosons) that can be pair-produced in a white dwarf
and then escape to contribute to its cooling. We show, in particular, that we
can severely constrain the parameter space of models with dark forces and light
hidden sectors (lighter than a few tens of keV). The bounds we find are often
more competitive than those from current lab searches and those expected from
most future searches.Comment: 25 pages, 8 figures, equivalent to published versio
Updating Bounds on -Parity Violating Supersymmetry from Meson Oscillation Data
We update the bounds on -parity violating supersymmetry originating from
meson oscillations in the and systems. To this end, we
explicitly calculate all corresponding contributions from -parity violating
operators at the one-loop level, thereby completing and correcting existing
calculations. We apply our results to the derivation of bounds on -parity
violating couplings, based on up-to-date experimental measurements. In
addition, we consider the possibility of cancellations among flavor-changing
contributions of various origins, e.g. from multiple -parity violating
couplings or -parity conserving soft terms. Destructive interferences among
new-physics contributions could then open phenomenologically allowed regions,
for values of the parameters that are naively excluded when the parameters are
varied individually.Comment: 53 pages, 10 figures, 2 tables; final versio
Long-lived Sterile Neutrinos at the LHC in Effective Field Theory
We study the prospects of a displaced-vertex search of sterile neutrinos at
the Large Hadron Collider (LHC) in the framework of the neutrino-extended
Standard Model Effective Field Theory (SMEFT). The production and decay of
sterile neutrinos can proceed via the standard active-sterile neutrino mixing
in the weak current, as well as through higher-dimensional operators arising
from decoupled new physics. If sterile neutrinos are long-lived, their decay
can lead to displaced vertices which can be reconstructed. We investigate the
search sensitivities for the ATLAS/CMS detector, the future far-detector
experiments: AL3X, ANUBIS, CODEX-b, FASER, MATHUSLA, and MoEDAL-MAPP, and at
the proposed fixed-target experiment SHiP. We study scenarios where sterile
neutrinos are predominantly produced via rare charm and bottom mesons decays
through minimal mixing and/or dimension-six operators in the SMEFT
Lagrangian. We perform simulations to determine the potential reach of
high-luminosity LHC experiments in probing the EFT operators, finding that
these experiments are very competitive with other searches.Comment: v1: 35 pages + Appendix, 12 figures, 17 tables; v2: accepted for
publication in JHEP, typos corrected, reasoning for neglecting direct
production of sterile neutrinos via parton collisions added upon referee's
suggestion, results unchange
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