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In supersymmetric models, scalar top quarks, or stops, generically have parity-violating couplings to top quarks. As a result, tops produced in stop decays should be polarized. In this paper, we will argue that this effect may be observable…

High Energy Physics - Phenomenology · Physics 2009-04-03 Maxim Perelstein , Andreas Weiler

During the LEP2 operation, the 4 LEP experiments have collected data at centre-of-mass energies up to 209 GeV. Those data have been analysed in the search of charginos, neutralinos and sfermions in the framework of the Minimal…

High Energy Physics - Experiment · Physics 2007-05-23 T. Alderweireld

This paper presents a statistical combination of searches targeting final states with two top quarks and invisible particles, characterised by the presence of zero, one or two leptons, at least one jet originating from a $b$-quark and…

High Energy Physics - Experiment · Physics 2023-06-19 ATLAS Collaboration

A multitude of searches have already been performed by the ATLAS and CMS collaborations at the LHC to probe the heavy Higgses of the Minimal Supersymmetric Standard Model (MSSM) through their decay to the Standard Model particles. In this…

High Energy Physics - Phenomenology · Physics 2016-10-26 Rahool K. Barman , Biplob Bhattacherjee , Amit Chakraborty , Arghya Choudhury

Simplified Models are a useful way to characterize new physics scenarios for the LHC. Particle decays are often represented using non-renormalizable operators that involve the minimal number of fields required by symmetries. Generalizing to…

High Energy Physics - Phenomenology · Physics 2016-08-26 Timothy Cohen , Matthew J. Dolan , Sonia El Hedri , James Hirschauer , Nhan Tran , Andrew Whitbeck

We introduce a set of minimal simplified models for dark matter interactions with the Standard Model, connecting the two sectors via either a scalar or pseudoscalar particle. These models have a wider regime of validity for dark matter…

High Energy Physics - Phenomenology · Physics 2015-06-23 Matthew R. Buckley , David Feld , Dorival Goncalves

We present updated results for the production cross sections of slepton pairs and neutralino-chargino pairs at the LHC with next-to-next-to logarithmic precision matched at approximate QCD next-to-next-to leading order. The explored range…

High Energy Physics - Phenomenology · Physics 2020-11-24 Juri Fiaschi , Michael Klasen

We investigate squark and gluino pair production at LHC (CMS) with subsequent decays into quarks, leptons and LSP in models with effective supersymmetry where third generation of squarks is relatively light while the first two generations…

High Energy Physics - Phenomenology · Physics 2007-05-23 S. I. Bityukov , N. V. Krasnikov

We address the question of how to determine the stop mixing angle and its CP-violating phase at the LHC. As an observable we discuss ratios of branching ratios for different decay modes of the light stop ~t_1 to charginos and neutralinos.…

High Energy Physics - Phenomenology · Physics 2015-03-13 Krzysztof Rolbiecki , Jamie Tattersall , Gudrid Moortgat-Pick

We compare the first results on searches for supersymmetry with the Large Hadron Collider (LHC) to the current and near-term performance of experiments sensitive to neutralino dark matter. We limit our study to the particular slices of…

High Energy Physics - Phenomenology · Physics 2011-08-08 Stefano Profumo

In this letter, we study the implications of precise gauge coupling unification on supersymmetric particle masses. We argue that precise unification favors the superpartner masses that are in the range of several TeV and well beyond. We…

High Energy Physics - Phenomenology · Physics 2023-09-25 Prudhvi N. Bhattiprolu , James D. Wells

Indirect limits on the mass of the lightest neutralino are derived from the results of searches for charginos, neutralinos, and sleptons performed with data taken by the ALEPH Collaboration at centre-of-mass energies near the Z peak and at…

High Energy Physics - Experiment · Physics 2012-08-27 The ALEPH Collaboration

We examine current collider constraints on some simple $Z^\prime$ models that fit neutral current $B-$anomalies, including constraints coming from measurements of Standard Model (SM) signatures at the LHC. The `MDM' simplified model is not…

High Energy Physics - Phenomenology · Physics 2020-01-29 B. C. Allanach , J. M. Butterworth , Tyler Corbett

Although the Large Hadron Collider (LHC) has not observed supersymmetric (SUSY) partners of the Standard Model particles, their existence is not ruled out yet. One recently explored scenario in which there are light SUSY partners that have…

High Energy Physics - Phenomenology · Physics 2014-04-23 Chul Kim , Ahmad Idilbi , Thomas Mehen , Yeo Woong Yoon

Top squark (stop) is a crucial part of supersymmetric models (SUSY) to understand the naturalness problem. Other than the traditional stop pair production, the single production via electroweak interaction provides signals with distinctive…

High Energy Physics - Phenomenology · Physics 2020-09-03 Tian-Peng Tang , Hang Zhou , Ning Liu

We compute the full O(alpha_s) supersymmetric QCD corrections for neutralino-stop co-annihilation into electroweak gauge and Higgs bosons in the Minimal Supersymmetric Standard Model (MSSM). We show that these annihilation channels are…

High Energy Physics - Phenomenology · Physics 2013-04-09 J. Harz , B. Herrmann , M. Klasen , K. Kovarik , Q. Le Boulc'h

Weak scale supersymmetry is often said to be fine-tuned, especially if the matter content is minimal. This is not true if there is a large A term for the top squarks. We present a systematic study on fine-tuning in minimal supersymmetric…

High Energy Physics - Phenomenology · Physics 2009-09-29 Ryuichiro Kitano , Yasunori Nomura

We discuss the fine-tuning issue within the MSSM framework. Following the idea that the fine-tuning can measure effects of some missing mechanism, we impose non-universal gaugino masses at the GUT scalem and explore the low scale…

High Energy Physics - Phenomenology · Physics 2017-08-02 Ali Cici , Zerrin Kirca , Cem Salih Un

This work investigates the possibility of a long-lived stop squark in supersymmetric models with the neutralino as the lightest supersymmetric particle (LSP). We study the implications of meta-stable stops on the sparticle mass spectra and…

High Energy Physics - Phenomenology · Physics 2014-11-20 M. Johansen , J. Edsjo , S. Hellman , D. Milstead

We use the LHC Higgs data to derive updated constraints on electroweak-scale sterile neutrinos that naturally occur in many low-scale seesaw extensions of the Standard Model to explain the neutrino masses. We also analyze the signal…

High Energy Physics - Phenomenology · Physics 2018-03-21 Arindam Das , P. S. Bhupal Dev , C. S. Kim