arXiv subjects

Vasiliki A. Mitsou

Publications and source records attributed to Vasiliki A. Mitsou.

At least 19 recordsLinked to original sources

arXiv2026

Magnetic monopoles: from Dirac to the Large Hadron Collider

One of the basic properties of magnetism is that a magnet has always two poles, north and south, which cannot be separated into isolated poles, the magnetic monopoles. There are strong theoretical arguments in favour of monopoles' existence, but in spite of extensive searches they are yet to be found. In this review article, after highlighting briefly the theoretical foundations of monopoles, a historical overview of experimental endeavours to observe them is given, with emphasis on the state-of-the-art of searches in cosmic and collider experiments and in particular the Large Hadron Collider at CERN.

hep-ex↗

arXiv2026

Constraining magnetic monopoles and multiply charged particles with diphoton events at the LHC

The LHC is achieving energies never reached before, opening up possibilities for the discovery of exotic particles in the TeV mass range. Such states include magnetic monopoles, which can explain the electric charge quantisation and restore the symmetry in Maxwell's equations with respect to the magnetic and electric fields. Scenarios proposed to shed light to dark matter and neutrino masses introduce high-electric-charge objects (HECOs). The existence of both classes of particles can be probed in precision measurements in a manner complementary to direct searches. We focus on the contributions of such virtual particles to light-by-light scattering in the context of effective field theories and a Born-Infeld scenario. Specifically, measurements of central exclusive production of photon pairs with proton tagging carried out by the CMS-TOTEM Precision Proton Spectrometer with LHC Run 2 proton-proton collision data are used to constrain magnetic monopole and HECOs. Resummation techniques have been employed to deal with the large HECO-photon coupling. Masses of up to a few tens of TeV have been excluded for monopoles and HECOs of various spins and magnetic and electric charges, respectively.

hep-ph↗

arXiv2026

Promoting Green Computing in High Energy Physics and Astrophysics

This research topic aims to explore and promote strategies for green computing in high-energy physics and astrophysics. The primary objectives include assessing current energy consumption patterns, identifying opportunities for resource optimization, and fostering cross-disciplinary collaborations to enhance sustainability. Key questions to be addressed include: What are the current energy demands in these fields? How can existing technologies be leveraged for more efficient resource usage? What synergies can be identified between high-energy and astrophysics projects to promote green computing?

physics.comp-ph↗

arXiv2026

Magnetic-monopole resummation justifies perturbatively calculated collider production cross sections

A one-loop resummation scheme, inspired by Dyson-Schwinger (DS) formalism of strongly coupled quantum field theories, is applied to spin-1/2 magnetic monopoles (MMs), in the context of an effective field theory (EFT), invariant under the gauge group U(1)_em x U(1)', where U(1)' is a dual strongly coupled Abelian interaction, associated with a "dark photon". The latter leads to a MM appearing as a limiting case of a "dyon", with a tiny "electric charge", compensated by a huge wave-function renormalization of the MM, thereby leading to a finite renormalized MM-photon coupling. An ultra-violet fixed point structure is found in the resummed theory, which is purely non-perturbative due to different boundary conditions of the resummation equations, compared to the weak coupling (perturbative) case. The renormalized coupling of the MM to the electromagnetic photon in the fixed-point theory is identified with the magnetic charge, compatible with the Dirac quantization condition. This provides for the first time a formal justification of the use of tree-level Drell-Yan and photon-fusion MM production processes in collider searches, and of the corresponding cross sections and MM mass bounds thereof. The latter provide a means to constrain the resummed-EFT parameters experimentally. The DS resummation applies here primarily to elementary MMs. However, this approach may also be applied to the last stage (collapse) of the formation of composite MM pairs at colliders, in case they behave as quantum excitations, with their core radius comparable to the Compton wavelength, thereby avoiding the extreme suppression of their production.

hep-ph↗

arXiv2026

The COSMIC WISPers White Paper: The physics case for Weakly Interacting Slim Particles

Axions and other very weakly interacting slim particles (WISPs), with masses below 1 GeV, arise naturally in many extensions of the Standard Model of particle physics. In particular, they could offer a new framework to explain the nature of dark matter and may help address a range of puzzling observations in astrophysics and particle physics. This review provides an overview of ongoing WISP searches and outlines the prospects for the next decade, spanning their theoretical motivation, indirect signatures in astrophysical observations, and dedicated laboratory experiments. It is based on the work carried on by the EU-funded COST Action ``Cosmic WISPers in the Dark Universe: Theory, astrophysics, and experiments'' (CA21106, https://www.cost.eu/actions/CA21106). This network plays a key role in coordinating and supporting WISP searches across Europe, while also contributing to the development of a roadmap aimed at securing European leadership in this research area. It is emphasized that Europe is currently pursuing a rich, diverse, and cost-effective experimental program, with the potential to deliver one or more transformative discoveries.

hep-ph↗

arXiv2025

t-channel dark matter at the LHC -- a whitepaper

This report, summarising work achieved in the context of the LHC Dark Matter Working Group, investigates the phenomenology of $t$-channel dark matter models, spanning minimal setups with a single dark matter candidate and mediator to more complex constructions closer to UV-complete models. For each considered class of models, we examine collider, cosmological and astrophysical implications. In addition, we explore scenarios with either promptly decaying or long-lived particles, as well as featuring diverse dark matter production mechanisms in the early universe. By providing a unified analysis framework, numerical tools and guidelines, this work aims to support future experimental and theoretical efforts in exploring $t$-channel dark matter models at colliders and in cosmology.

hep-ph↗

arXiv2025

Minicharged Particle Sensitivity of the MAPP Outrigger Detector

We present a detailed study of the projected background-free sensitivity of the MAPP Outrigger Detector (OD) to minicharged particles (mCPs) at the High-Luminosity Large Hadron Collider (HL-LHC). As the first upgrade to the MAPP Experiment, the MAPP OD is a standalone detector designed to offer enhanced sensitivity to high-mass mCPs with intermediate effective charges. The MAPP OD is planned for installation in a duct adjacent to the MAPP-1 detector, located between the LHC's UA83 gallery and the beamline. Considering mCP production via the Drell-Yan mechanism and various meson decays, the results show that, at the 95% confidence level, the MAPP OD can extend the experiment's upper mass reach to mCP masses of approximately 200 GeV at the HL-LHC.

hep-ph↗

arXiv2025

Impact of resummation on the production and experimental bounds of scalar high-electric-charge objects

A one-loop Dyson-Schwinger-like resummation scheme is applied to scalar High-Electric-Charge compact Objects (HECOs), extending previous work on spin-1/2 case. The electromagnetic interactions of HECOs are considered within the framework of strongly coupled scalar Quantun Electrodynamics. The resummation amounts to determining non-trivial ultraviolet (UV) fixed points, at which the effective Lagrangian, which will lead to the pertinent predictions on the cross sections, is computed. In contrast to the fermionic HECO case, in which the fixed point structure was determined solely by the interactions of the HECOs with the photon field, in the scalar case the existence of non-trivial UV fixed points requires the presence of additional strong self interactions among the HECOs. Our resummation scheme, which is notably different from a lattice strong-coupling approach, makes the computation of the pertinent scalar-HECO-production cross sections reliable, thus allowing revisiting the mass bounds obtained from searches for such objects in current or future colliders. Our MadGraph implementation of the results leads to enhanced (up to ~30%) lower bounds on the mass of scalar HECOs, as compared to those extracted from the tree-level processes typically used in LHC collider searches by ATLAS and MoEDAL experiments.

hep-ph↗

arXiv2024

Revisiting experimental mass limits on HECOs using Dyson-Schwinger resummation

High-Electric-Charge compact Objects (HECOs) appear in several theoretical particle physics models beyond the Standard Model, and are actively searched for in current colliders, such as the Large Hadron Collider (LHC). In such searches, mass bounds of these objects have been placed, using Drell-Yan and Photon-Fusion processes at tree level so far. However, such estimates are not reliable, given that, as a result of the large values of the electric charge of the HECO, perturbative QED calculations break down. We present a Dyson-Schwinger-like resummation scheme, which allows for a large gauge coupling and thus makes the computation of the pertinent HECO-production cross sections reliable, thus allowing us to extract improved mass bounds for such objects from ATLAS and MoEDAL searches.

hep-ph↗

arXiv2024

Resummation schemes for high-electric-charge objects leading to improved experimental mass limits

High-Electric-Charge compact Objects (HECOs) appear in several theoretical particle physics models beyond the Standard Model, and are actively searched for in current colliders, such as the Large Hadron Collider at CERN. In such searches, mass bounds of these objects have been placed, using Drell-Yan and photon-fusion processes at tree level so far. However, such mass-bound estimates are not reliable, given that, as a result of the large values of the electric charge of the HECO, perturbative Quantum Electrodynamics calculations break down. In this work, we perform a Dyson-Schwinger resummation scheme (as opposed to lattice strong-coupling approach), which makes the computation of the pertinent HECO-production cross sections reliable, thus allowing us to extract improved mass bounds for such objects from ATLAS and MoEDAL searches.

hep-ph↗

arXiv2023

Searching for Minicharged Particles at the Energy Frontier with the MoEDAL-MAPP Experiment at the LHC

MoEDAL's Apparatus for Penetrating Particles (MAPP) Experiment is designed to expand the search for new physics at the LHC, significantly extending the physics program of the baseline MoEDAL Experiment. The Phase-1 MAPP detector (MAPP-1) is currently undergoing installation at the LHC's UA83 gallery adjacent to the LHCb/MoEDAL region at Interaction Point 8 and will begin data-taking in early 2024. The focus of the MAPP experiment is on the quest for new feebly interacting particles$\unicode{x2014}$avatars of new physics with extremely small Standard Model couplings, such as minicharged particles (mCPs). In this study, we present the results of a comprehensive analysis of MAPP-1's sensitivity to mCPs arising in the canonical model involving the kinetic mixing of a massless dark $U(1)$ gauge field with the Standard Model hypercharge gauge field. We focus on several dominant production mechanisms of mCPs at the LHC across the mass$\unicode{x2013}$mixing parameter space of interest to MAPP: Drell$\unicode{x2013}$Yan pair production, direct decays of heavy quarkonia and light vector mesons, and single Dalitz decays of pseudoscalar mesons. The $95\%$ confidence level background-free sensitivity of MAPP-1 for mCPs produced at the LHC's Run 3 and the HL-LHC through these mechanisms, along with projected constraints on the minicharged strongly interacting dark matter window, are reported. Our results indicate that MAPP-1 exhibits sensitivity to sizable regions of unconstrained parameter space and can probe effective charges as low as $8 \times 10^{-4}\:e$ and $6 \times 10^{-4}\:e$ for Run 3 and the HL-LHC, respectively.

hep-ph↗

arXiv2022

Discovery prospects for long-lived multiply charged particles at the LHC

In this work, we aim to provide a comprehensive and largely model independent investigation on prospects to detect long-lived multiply charged particles at the LHC. We consider particles with spin 0 and $\frac{1}{2}$, with electric charges in range $1 \le |Q/e| \le 8$, which are singlet or triplet under $SU(3)_C$. Such particles might be produced as particle-antiparticle pairs and propagate through detectors, or form a positronium(quarkonium)-like bound state. We consider both possibilities and estimate lower mass bounds on new particles, that can be provided by ATLAS, CMS and MoEDAL experiments at the end of Run 3 and HL-LHC data taking periods. We find out that the sensitivities of ATLAS and CMS are generally stronger than those of MoEDAL at Run 3, while they may be competitive at HL-LHC for $3 \lesssim |Q/e| \lesssim 7$ for all types of long-lived particles we consider.

hep-ph↗

arXiv2021

LHC experiments for long-lived particles of the dark sector

Dark matter scenarios are being tested at the LHC in the general-purpose experiments through promptly decaying states. In parallel, new dedicated detectors have been proposed for the LHC to probe dark matter portal theories predicting long-lived particles that decay away from the interaction point: MoEDAL-MAPP, MoEDAL-MALL, FASER, SND@LHC, CODEX-b, MATHUSLA, AL3X, ANUBIS, FACET, milliQan, FORMOSA. In addition, the SHiP beam-dump experiment is planned to operate with the SPS beam to extend the discovery reach for such particles. The detector design and expected physics sensitivity of these experiments is presented with emphasis on scenarios explaining the nature of dark matter.

hep-ex↗

arXiv2021

Results and future plans of the MoEDAL experiment

The unprecedented collision energy of the LHC has opened up a new discovery frontier. Unfortunately, signs of new physics have yet to be seen. The LHC's first dedicated search experiment, MoEDAL, started data taking for LHC Run 2. MoEDAL is designed to search highly ionising particle avatars of new physics using pp and heavy-ion collisions at the LHC. The planned upgrade for MoEDAL at Run 3 - the MAPP detector (MoEDAL Apparatus for Penetrating Particles) - will extend MoEDAL's physics reach to include feebly interacting and long-lived messengers of physics beyond the Standard Model. This will allow us to explore a number of models of new physics, including dark-sector models, in a complementary way to that of conventional LHC collider detectors. This article focuses on recent results and plans for the LHC Run 3.

hep-ex↗

arXiv2020

Magnetic monopoles revisited: Models and searches at colliders and in the Cosmos

In this review, we discuss recent developments in both the theory and the experimental searches of magnetic monopoles in past, current and future colliders and in the Cosmos. The theoretical models include, apart from the standard Grand Unified Theories, extensions of the Standard Model that admit magnetic monopole solutions with finite energy and masses that can be as light as a few TeV. Specifically, we discuss, among other scenarios, modified Cho-Maison monopoles and magnetic monopoles in (string-inspired, higher derivative) Born-Infeld extensions of the hypercharge sector of the Standard Model. We also outline the conditions for which effective field theories describing the interaction of monopoles with photons are valid and can be used for result interpretation in monopole production at colliders. The experimental part of the review focuses on, past and present, cosmic and collider searches, including the latest bounds on monopole masses and magnetic charges by the ATLAS and MoEDAL experiments at the LHC, as well as prospects for future searches.

hep-ph↗

arXiv2019

Dark matter: experimental and observational status

This brief review covers recent results on searches for dark matter in collider experiments, as well as from direct and indirect detection observatories. It focuses on generic searches for dark matter signatures at the LHC, e.g. mono-X, dijets, etc. Recently observed astrophysical signals that may provide hints of dark matter are also discussed.

hep-ph↗

arXiv2019

Monopole production via photon fusion at the LHC

The existence of magnetic monopoles, also predicted in some GUT theories, would symmetrise Maxwell equations and explain the charge quantisation. Searches for them are being performed in cosmic telescopes as well as in collider experiments, such as MoEDAL and ATLAS. In this report, we focus on the, least explored, photon-fusion mechanism, yet Drell-Yan results are discussed, too. Cross sections for monopoles of spin 0, 1/2 and 1 for an effective monopole-velocity-dependent magnetic charge are presented. For spin-1/2 and spin-1 monopoles, a magnetic-moment term is included, which is treated as a new phenomenological parameter and, together with the velocity-dependent coupling, allows for a perturbative treatment of the cross-section calculation. We present an appropriate implementation of photon-fusion and Drell-Yan processes into MadGraph UFO models, aimed to serve as a useful tool in monopole searches at LHC, especially for photon fusion, given that it has not been considered by experimental collaborations recently. Moreover, the experimental implications of such perturbatively reliable monopole searches are discussed.

hep-ph↗

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↗