146 research outputs found
Heavy stable charged tracks as signatures of non-thermal dark matter at the LHC : a study in some non-supersymmetric scenarios
We consider two theoretical scenarios, each including a -odd
sector and leading to an elementary dark matter candidate. The first one is a
variant of the Type-III seesaw model where one lepton triplet is
-odd, together with a heavy sterile neutrino. It leads to a
fermionic dark matter, together with the charged component of the triplet being
a quasi-stable particle which decays only via a higher-dimensional operator
suppressed by a high scale. The second model consists of an inert scalar
doublet together with a -odd right-handed Majorana neutrino
dark matter. A tiny Yukawa coupling delays the decay of the charged component
of the inert doublet into the dark matter candidate, making the former
long-lived on the scale of collider detectors. The parameter space of each
model has been constrained by big-bang nucleosynthesis constraints, and also by
estimating the contribution to the relic density through freeze-out of the
long-lived charged particle as well the freeze-in production of the dark matter
candidate. We consider two kinds of signals at the Large Hadron Collider for
the first kind of models, namely two charged tracks and single track + MET. For
the second kind, the characteristic signals are opposite as well as same-sign
charged track pairs. We perform a detailed analysis using event selection
criteria consistent with the current experimental programmes. It is found that
the scenario with a lepton triplet can be probed upto 960(1190) GeV with an
integrated luminosity of 300(3000) , while the corresponding numbers
for the inert doublet scenario are 630(800) GeV. Furthermore, the second kind
of signal mentioned in each case allows us to differentiate different dark
matter scenarios from each other.Comment: v2:published in JHEP: Minor changes in text, Appendix added: 26
pages, 8 figures, 6 table
Implications of Unitarity and Charge Breaking Minima in Left-Right Symmetric Model
We examine the usefulness of the unitarity conditions in Left-Right symmetric
model which can translate into giving a stronger constraint on the model
parameters together with the criteria derived from vacuum stability and
perturbativity. In this light, we demonstrate the bounds on the masses of the
physical scalars present in the model and find the scenario where multiple
scalar modes are in the reach of Large Hadron Collider. We also analyse the
additional conditions that can come from charge breaking minima in this
context.Comment: v2: Accepted for publication in Phys. Rev. D, reference added, minor
change in the text, 16 pages, 2 figure
Higgs vacuum stability and inflationary dynamics after BICEP2 and PLANCK dust polarisation data
If the recent detection of mode polarization of the Cosmic Microwave
Background by BICEP2 observations, withstand the test of time after the release
of recent PLANCK dust polarisation data, then it would surprisingly put the
inflationary scale near Grand Unification scale if one considers single-field
inflationary models. On the other hand, Large Hadron Collider has observed the
elusive Higgs particle whose presently observed mass can lead to electroweak
vacuum instability at high scale GeV). In this
article, we seek for a simple particle physics model which can simultaneously
keep the vacuum of the theory stable and yield high-scale inflation
successfully. To serve our purpose, we extend the Standard Model of particle
physics with a gauged symmetry which spontaneously breaks down
just above the inflationary scale. Such a scenario provides a constrained
parameter space where both the issues of vacuum stability and high-scale
inflation can be successfully accommodated. The threshold effect on the Higgs
quartic coupling due to the presence of the heavy inflaton field plays an
important role in keeping the electroweak vacuum stable. Furthermore, this
scenario is also capable of reheating the universe at the end of inflation.
Though the issues of Dark Matter and Dark Energy, which dominate the late-time
evolution of our universe, cannot be addressed within this framework, this
model successfully describes the early universe dynamics according to the Big
Bang model.Comment: Title and text are modified to match the accepted version in JCAP. 22
pages, 3 figures, Latex fil
Impact of Climate Change in Physical Activity and Competitive Sports: Adaptive Measures and Evaluating Future Impacts in Arunachal Pradesh, India
The aim of this paper is to make a detailed study on climate change\u27s impacts on physical activity and organized competitive sports with further attention paid to their adaptation efforts and evaluating the future impacts with special reference to Arunachal Pradesh, India. Linkages between climate and human activity cannot be ignored and it is a universal phenomenon and is certainly possible due to adaptations. These adaptations have direct linkage with physical, mental, emotional, social and overall wellbeing of human beings. Ignoring the degree of adaptation could impact the health upto severe consequences due to climate change. The relationship between sport and environment has to be examined to understand how environment and climatic parameters impacts sport in terms of training, performance and sports injuries. Arunachal Pradesh is a hub of youth potentials especially in sports. Looking at the present climatic crisis, the study aims to assess the impacts of climate change, and measures to be taken by organized competitive sport entities to adapt to the impacts. The study adopts a descriptive analysis including both qualitative and quantitative assessment by exploring secondary information. The findings of the study states that most of the outdoor sport activities especially endurance sports are strongly influenced by meteorological parameters. The effects of weather on sports are varied, performances can get reduced or improved, becomes very severe during extreme weather conditions leading to threat for life. If climate change progresses in scope and severity as predicted, no doubt physical activity and outdoor organized competitive sports is under threat. The valence of this paper lies in its conceptualization of the climate vulnerability on sport activities and its potential to inspire future research and interest in this domain. However, it is important for government, agencies, sports organizations, coaches, athletes, environmentalists, and health experts to have the tools to identify the risks and understand their vulnerabilities
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