65 research outputs found
Search for the Top Partner at the LHC using Multi-b-Jet Channels
Vector-like quarks are introduced in various new physics models beyond the
standard model (SM) at the TeV scale. We especially consider the case that the
quark is singlet (triplet) under the SU(2) (SU(3)) gauge group and
couples only to the third generation quarks of the SM. The vector-like quark of
this kind is often called a top partner. The top partoner decays into
and . In the ATLAS and CMS collaborations, the top partner has
been searched in the final states of and , while the search based on
the decay mode has not been started yet. However, the decay into
is important since it is significantly enhanced if some strong dynamics
exists in the TeV scale. In the presence of a light higgs boson, the decay mode
followed by produces three bottom quarks. We study
the sensitivity for the top partner using multi-b-jet events at the 8 TeV run
of the LHC experiment. The multi-b-jet eventss turn out to play a complementary
role to the existing and searches by the ATLAS and CMS
collaborations.Comment: 26 pages, 9 figures, 10 Table
Searching for Dark Absorption with Direct Detection Experiments
We consider the absorption by bound electrons of dark matter in the form of
dark photons and axion-like particles, as well as of dark photons from the Sun,
in current and next-generation direct detection experiments. Experiments
sensitive to electron recoils can detect such particles with masses between a
few eV to more than 10 keV. For dark photon dark matter, we update a previous
bound based on XENON10 data and derive new bounds based on data from XENON100
and CDMSlite. We find these experiments to disfavor previously allowed
parameter space. Moreover, we derive sensitivity projections for SuperCDMS at
SNOLAB for silicon and germanium targets, as well as for various possible
experiments with scintillating targets (cesium iodide, sodium iodide, and
gallium arsenide). The projected sensitivity can probe large new regions of
parameter space. For axion-like particles, the same current direction detection
data improves on previously known direct-detection constraints but does not
bound new parameter space beyond known stellar cooling bounds. However,
projected sensitivities of the upcoming SuperCDMS SNOLAB using germanium can go
beyond these and even probe parameter space consistent with possible hints from
the white dwarf luminosity function. We find similar results for dark photons
from the sun. For all cases, direct-detection experiments can have
unprecedented sensitivity to dark-sector particles.Comment: 18 pages, 5 figures, Figs. 3 and 4 fixed, appendices adde
Effect of Forest Grazing in Summer on Grazing Behaviour, Heart Beat and Heat Production of Beef Cows
In Japan summer is very hot and humid, particularly in daytime, therefore the supply of shade to animals is important. At the same time, a lot of forest and partial forest area is under-utilised in most of the mountain areas. Introduction of animals to forest areas might result in not only less labour demanding animal management, but also in the efficient weeding in the forest (Sugimoto et al., 1999). We compared the grazing behaviour, heart beat and heat production of beef cows in partial forest with those in the normal grazing place outside the forest
Gluino Decay as a Probe of High Scale Supersymmetry Breaking
A supersymmetric standard model with heavier scalar supersymmetric particles
has many attractive features. If the scalar mass scale is O(10 - 10^4) TeV, the
standard model like Higgs boson with mass around 125 GeV, which is strongly
favored by the LHC experiment, can be realized. However, in this scenario the
scalar particles are too heavy to be produced at the LHC. In addition, if the
scalar mass is much less than O(10^4) TeV, the lifetime of the gluino is too
short to be measured. Therefore, it is hard to probe the scalar particles at a
collider. However, a detailed study of the gluino decay reveals that two body
decay of the gluino carries important information on the scalar scale. In this
paper, we propose a test of this scenario by measuring the decay pattern of the
gluino at the LHC.Comment: 29 pages, 9 figures; version published in JHE
Feebly-interacting particles: FIPs 2020 workshop report
With the establishment and maturation of the experimental programs searching for new physics with sizeable couplings at the LHC, there is an increasing interest in the broader particle and astrophysics community for exploring the physics of light and feebly-interacting particles as a paradigm complementary to a New Physics sector at the TeV scale and beyond. FIPs 2020 has been the first workshop fully dedicated to the physics of feebly-interacting particles and was held virtually from 31 August to 4 September 2020. The workshop has gathered together experts from collider, beam dump, fixed target experiments, as well as from astrophysics, axions/ALPs searches, current/future neutrino experiments, and dark matter direct detection communities to discuss progress in experimental searches and underlying theory models for FIPs physics, and to enhance the cross-fertilisation across different fields. FIPs 2020 has been complemented by the topical workshop Physics Beyond Colliders meets theory, held at CERN from 7 June to 9 June 2020. This document presents the summary of the talks presented at the workshops and the outcome of the subsequent discussions held immediately after. It aims to provide a clear picture of this blooming field and proposes a few recommendations for the next round of experimental results
Testing Little Higgs Mechanism at Future Colliders
In the framework of the little higgs scenario, coupling constants of several
interactions are related to each other to guarantee the stability of the higgs
boson mass at one-loop level. This relation is called the little higgs
mechanism. We discuss how accurately the relation can be tested at future e+e-
colliders, with especially focusing on the top sector of the scenario using a
method of effective lagrangian. In order to test the mechanism at the top
sector, it is important to measure the Yukawa coupling of the top partner. We
consider higgs associated production and threshold production of the top
partner, and find that the mechanism can be tested precisely using the
associate production when the center of mass energy is large enough. The
threshold production also allows us to test it even if the center mass energy
is not so large.Comment: 22 pages, 5 figures, 2 tables ; v2 minor correction
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