arXiv subjects

Vasiliki A. Mitsou

Publications and source records attributed to Vasiliki A. Mitsou.

At least 37 records · Page 2Linked to original sources

arXiv2017

Hunting magnetic monopoles and more with MoEDAL at the LHC

The MoEDAL experiment at the LHC is optimised to detect highly-ionising particles such as magnetic monopoles, dyons and (multiply) electrically-charged stable massive particles predicted in a number of theoretical scenarios. MoEDAL, deployed in the LHCb cavern, combines passive nuclear track detectors with magnetic monopole trapping volumes, while backgrounds are being monitored with an array of MediPix detectors. The detector concept and its physics reach is presented with emphasis given to recent results on monopoles.

hep-ex↗

arXiv2017

The MoEDAL experiment at the LHC: status and results

The MoEDAL experiment at the LHC is optimised to detect highly ionising particles such as magnetic monopoles, dyons and (multiply) electrically charged stable massive particles predicted in a number of theoretical scenarios. MoEDAL, deployed in the LHCb cavern, combines passive nuclear track detectors with magnetic monopole trapping volumes (MMTs), while spallation-product backgrounds are being monitored with an array of MediPix pixel detectors. An introduction to the detector concept and its physics reach, complementary to that of the large general purpose LHC experiments ATLAS and CMS, will be given. Emphasis is given to the recent MoEDAL results at 13 TeV, where the null results from a search for magnetic monopoles in MMTs exposed in 2015 LHC collisions set the world-best limits on particles with magnetic charges more than 1.5 Dirac charge. The potential to search for heavy, long-lived supersymmetric electrically-charged particles is also discussed.

hep-ex↗

arXiv2016

Physics reach of MoEDAL at LHC: magnetic monopoles, supersymmetry and beyond

MoEDAL is a pioneering experiment designed to search for highly ionising messengers of new physics such as magnetic monopoles or massive (pseudo-)stable charged particles, that are predicted to exist in a plethora of models beyond the Standard Model. Its ground-breaking physics program defines a number of scenarios that yield potentially revolutionary insights into such foundational questions as, are there extra dimensions or new symmetries, what is the mechanism for the generation of mass, does magnetic charge exist, what is the nature of dark matter, and, how did the big-bang develop at the earliest times. MoEDAL's purpose is to meet such far-reaching challenges at the frontier of the field. The physics reach of the existing MoEDAL detector is discussed, giving emphasis on searches for magnetic monopoles, supersymmetric (semi)stable partners, doubly charged Higgs bosons, and exotic structures such as black-hole remnants in models with large extra spatial dimensions and D-matter in some brane theories.

hep-ph↗

arXiv2015

Conciliating SUSY with the Z-peaked excess

The ATLAS experiment observed an excess at the $3σ$ level in the channel of $Z$ boson, jets and high missing transverse momentum in the full 2012 dataset at 8 TeV while searching for SUSY. The question arises whether the abundance and the kinematical features of this excess are compatible with the yet unconstrained supersymmetric realm, respecting at the same time the measured Higgs boson properties and dark matter density. By trying to explain this signal with SUSY we find that only relatively light gluinos together with a heavy neutralino NLSP decaying predominantly to a $Z$ boson plus a light gravitino could reproduce the excess. We construct an explicit general gauge mediation model able to match the observed signal. More sophisticated models could also reproduce the signal, as long as it features light gluinos, or heavy particles with a strong production cross section, producing at least one $Z$ boson in its decay chain. The implications of our findings for the Run II at LHC with the scaling on the $Z$ peak, as well as for the direct search of gluinos and other SUSY particles, are also discussed.

hep-ph↗

arXiv2015

MoEDAL: Seeking magnetic monopoles and more at the LHC

The MoEDAL experiment (Monopole and Exotics Detector at the LHC) is designed to directly search for magnetic monopoles and other highly ionising stable or metastable particles arising in various theoretical scenarios beyond the Standard Model. Its physics goals --largely complementary to the multi-purpose LHC detectors ATLAS and CMS-- are accomplished by the deployment of plastic nuclear track detectors combined with trapping volumes for capturing charged highly ionising particles and TimePix pixel devices for monitoring. This paper focuses on the status of the detectors and the prospects for LHC Run II.

physics.ins-det↗

arXiv2015

R-parity violating supersymmetry and neutrino physics: experimental signatures

$R$-parity violating supersymmetric models (RPV SUSY) are becoming increasingly more appealing than its $R$-parity conserving counterpart in view of the hitherto non-observation of SUSY signals at the LHC. In this paper, we discuss RPV scenarios where neutrino masses are naturally generated, namely RPV through bilinear terms (bRPV) and the $μ$-from-$ν$ supersymmetric standard model ($μν$SSM). The latter is characterised by a rich Higgs sector that easily accommodates a 125-GeV Higgs boson. The phenomenology of such models at the LHC is reviewed, giving emphasis on final states with displaced objects, and relevant results obtained by LHC experiments are presented. The implications for dark matter for these theoretical proposals is also addressed.

hep-ph↗

arXiv2015

Exploring neutrino physics at LHC via R-parity violating SUSY

R-parity violating supersymmetric models (RPV SUSY) are becoming increasingly more appealing than its R-parity conserving counterpart in view of the hitherto non-observation of SUSY signals at the LHC. In this talk, RPV scenarios where neutrino masses are naturally generated are discussed, namely RPV through bilinear terms (bRPV) and the "mu from nu" supersymmetric standard model. The latter is characterised by a rich Higgs sector that easily accommodates a 125-GeV Higgs boson. The phenomenology of such models at the LHC is reviewed, giving emphasis on final states with displaced objects, and relevant results obtained by LHC experiments are presented. The implications for dark matter for these theoretical proposals is also addressed.

hep-ph↗

arXiv2015

Hunting physics beyond the standard model with unusual $W^\pm$ and $Z$ decays

Nonstandard on-shell decays of $W^\pm$ and $Z$ bosons are possible within the framework of extended supersymmetric models, i.e., with singlet states and/or new couplings compared to the minimal supersymmetric standard model. These modes are typically encountered in regions of the parameter space with light singlet-like scalars, pseudoscalars, and neutralinos. In this letter we emphasize how these states can lead to novel signals at colliders from $Z$- or $W^\pm$-boson decays with prompt or displaced multileptons/tau jets/jets/photons in the final states. These new modes would give distinct evidence of new physics even when direct searches remain unsuccessful. We discuss the possibilities of probing these new signals using the existing LHC run-I data set. We also address the same in the context of the LHC run-II, as well as for the future colliders. We exemplify our observations with the "$μ$ from $ν$" supersymmetric standard model, where three generations of right-handed neutrino superfields are used to solve shortcomings of the minimal supersymmetric standard model. We also extend our discussion for other variants of supersymmetric models that can accommodate similar signatures.

hep-ph↗

arXiv2014

The physics case for the MoEDAL experiment at LHC

The MoEDAL experiment (Monopole and Exotics Detector at the LHC) is designed to directly search for magnetic monopoles and other highly-ionising stable or metastable particles arising in theoretical scenarios beyond the Standard Model. Its physics goals are accomplished by the deployment of plastic nuclear track detectors combined with trapping volumes for capturing charged highly-ionising particles and TimePix pixel devices for monitoring. This paper is an overview of the MoEDAL physics reach, which is largely complementary to the programs of the large multi-purpose LHC detectors ATLAS and CMS.

hep-ph↗

arXiv2014

Probing the $μν$SSM with light scalars, pseudoscalars and neutralinos from the decay of a SM-like Higgs boson at the LHC

The "$μ$ from $ν$" supersymmetric standard model ($μν$SSM) can accommodate the newly discovered Higgs-like scalar boson with a mass around 125 GeV. This model provides a solution to the $μ$-problem and simultaneously reproduces correct neutrino physics by the simple use of right-handed neutrino superfields. These new superfields together with the introduced $R$-parity violation can produce novel and characteristic signatures of the $μν$SSM at the LHC. We explore the signatures produced through two-body Higgs decays into the new states, provided that these states lie below in the mass spectrum. For example, a pair produced light neutralinos depending on the associated decay length can give rise to displaced multi-leptons/taus/jets/photons with small/moderate missing transverse energy. In the same spirit, a Higgs-like scalar decaying to a pair of scalars/pseudoscalars can produce final states with prompt multi-leptons/taus/jets/photons.

hep-ph↗

arXiv2014

Overview of searches for dark matter at the LHC

Dark matter remains one of the most puzzling mysteries in Fundamental Physics of our times. Experiments at high-energy physics colliders are expected to shed light to its nature and determine its properties. This review talk focuses on recent searches for dark-matter signatures at the Large Hadron Collider, either within specific theoretical scenarios, such as supersymmetry, or in a model-independent scheme looking for mono-X events arising in WIMP-pair production.

hep-ex↗

arXiv2014

Probing neutrino physics at LHC through R-parity breaking supersymmetry

R-parity conservation is an ad-hoc assumption in the most popular versions of supersymmetric scenarios. Hence R-parity violation (RPV) not only is allowed but, if induced by bilinear terms (bRPV), it also provides an explanation for the observed neutrino masses and mixing. Here bRPV models are discussed, giving emphasis on the $μ$-from-$ν$ supersymmetric standard model, which is characterised by a rich Higgs sector that easily accommodates a 125-GeV Higgs boson. The phenomenology of such models at the Large Hadron Collider is reviewed and some recent results obtained by LHC experiments are presented. The possibility to extend such analyses to probe bRPV scenarios with a gravitino dark matter candidate is also explored.

hep-ph↗

arXiv2013

ATLAS Physics Results

The ATLAS experiment at the Large Hadron Collider at CERN has been successfully taking data since the end of 2009 in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV, and in heavy ion collisions. In these lectures, some of the most recent ATLAS results will be given on Standard Model measurements, the discovery of the Higgs boson, searches for supersymmetry and exotics and on heavy-ion results.

hep-ex↗

arXiv2013

Shedding Light on Dark Matter at Colliders

Dark matter remains one of the most puzzling mysteries in Fundamental Physics of our times. Experiments at high-energy physics colliders are expected to shed light to its nature and determine its properties. This review focuses on recent searches for dark-matter signatures at the Large Hadron Collider, also discussing related prospects in future e+e- colliders.

hep-ex↗

arXiv2013

Probing the "$μ$ from $ν$" supersymmetric standard model with displaced multileptons from the decay of a Higgs boson at the LHC

The "$μ$ from $ν$" supersymmetric standard model ($μν$SSM) cures the $μ$-problem and concurrently reproduces measured neutrino data by using a set of usual right-handed neutrino superfields. Recently, the LHC has revealed the first scalar boson which naturally makes it tempting to test $μν$SSM in the light of this new discovery. We show that this new scalar while decaying to a pair of unstable long-lived neutralinos, can lead to a distinct signal with non-prompt multileptons. With concomitant collider analysis we show that this signal provides an unmistakable signature of the model, pronounced with light neutralinos. Evidence of this signal is well envisaged with sophisticated displaced vertex analysis, which deserves experimental attention.

hep-ph↗

arXiv2013

Experimental status of particle and astroparticle searches for supersymmetry

An overview of supersymmetry searches is presented, covering collider experiments, direct and indirect searches for supersymmetric dark matter. Recent LHC experimental results are reviewed, and the constraints from B-meson decays are reported. Implications for supersymmetry of the latest direct and indirect searches are thoroughly discussed. The focus is on the complementarity of the various probes -- particle and astrophysical -- for constraining Supersymmetry.

hep-ph↗

arXiv2012

Highlights from SUSY searches with ATLAS

Supersymmetry (SUSY) is one of the most relevant scenarios of new physics searched by the ATLAS experiment at the CERN Large Hadron Collider. In this writeup the principal search strategies employed by ATLAS are outlined and the most recent results for analyses targeting SUSY discovery are discussed. A wide range of signatures is covered motivated by various theoretical scenarios and topologies: strong production, third-generation fermions, long-lived particles and R-parity violation, among others. The results are based on up to ~5 fb-1 of data recorded during 2010-2011 at sqrt(s) = 7 TeV centre-of-mass energy by the ATLAS experiment at the LHC.

hep-ex↗

arXiv2012

Looking for magnetic monopoles at LHC with diphoton events

Magnetic monopoles have been a subject of interest since Dirac established the relation between the existence of monopoles and charge quantization. The intense experimental search carried thus far has not met with success. The Large Hadron Collider is reaching energies never achieved before allowing the search for exotic particles in the TeV mass range. In a continuing effort to discover these rare particles we propose here other ways to detect them. We study the observability of monopoles and monopolium, a monopole-antimonopole bound state, at the Large Hadron Collider in the $γγ$ channel for monopole masses in the range 500-1000 GeV. We conclude that LHC is an ideal machine to discover monopoles with masses below 1 TeV at present running energies and with 5 fb$^{-1}$ of integrated luminosity.

hep-ph↗