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A. Arbey

Publications and source records attributed to A. Arbey.

At least 19 recordsLinked to original sources
arXiv2025

Future Circular Collider Feasibility Study Report: Volume 1, Physics, Experiments, Detectors

Volume 1 of the FCC Feasibility Report presents an overview of the physics case, experimental programme, and detector concepts for the Future Circular Collider (FCC). This volume outlines how FCC would address some of the most profound open questions in particle physics, from precision studies of the Higgs and EW bosons and of the top quark, to the exploration of physics beyond the Standard Model. The report reviews the experimental opportunities offered by the staged implementation of FCC, beginning with an electron-positron collider (FCC-ee), operating at several centre-of-mass energies, followed by a hadron collider (FCC-hh). Benchmark examples are given of the expected physics performance, in terms of precision and sensitivity to new phenomena, of each collider stage. Detector requirements and conceptual designs for FCC-ee experiments are discussed, as are the specific demands that the physics programme imposes on the accelerator in the domains of the calibration of the collision energy, and the interface region between the accelerator and the detector. The report also highlights advances in detector, software and computing technologies, as well as the theoretical tools /reconstruction techniques that will enable the precision measurements and discovery potential of the FCC experimental programme. This volume reflects the outcome of a global collaborative effort involving hundreds of scientists and institutions, aided by a dedicated community-building coordination, and provides a targeted assessment of the scientific opportunities and experimental foundations of the FCC programme.

hep-ex↗
arXiv2025

Future Circular Collider Feasibility Study Report: Volume 2, Accelerators, Technical Infrastructure and Safety

In response to the 2020 Update of the European Strategy for Particle Physics, the Future Circular Collider (FCC) Feasibility Study was launched as an international collaboration hosted by CERN. This report describes the FCC integrated programme, which consists of two stages: an electron-positron collider (FCC-ee) in the first phase, serving as a high-luminosity Higgs, top, and electroweak factory; followed by a proton-proton collider (FCC-hh) at the energy frontier in the second phase. FCC-ee is designed to operate at four key centre-of-mass energies: the Z pole, the WW production threshold, the ZH production peak, and the top/anti-top production threshold - delivering the highest possible luminosities to four experiments. Over 15 years of operation, FCC-ee will produce more than 6 trillion Z bosons, 200 million WW pairs, nearly 3 million Higgs bosons, and 2 million top anti-top pairs. Precise energy calibration at the Z pole and WW threshold will be achieved through frequent resonant depolarisation of pilot bunches. The sequence of operation modes remains flexible. FCC-hh will operate at a centre-of-mass energy of approximately 85 TeV - nearly an order of magnitude higher than the LHC - and is designed to deliver 5 to 10 times the integrated luminosity of the HL-LHC. Its mass reach for direct discovery extends to several tens of TeV. In addition to proton-proton collisions, FCC-hh is capable of supporting ion-ion, ion-proton, and lepton-hadron collision modes. This second volume of the Feasibility Study Report presents the complete design of the FCC-ee collider, its operation and staging strategy, the full-energy booster and injector complex, required accelerator technologies, safety concepts, and technical infrastructure. It also includes the design of the FCC-hh hadron collider, development of high-field magnets, hadron injector options, and key technical systems for FCC-hh.

physics.acc-ph↗
arXiv2025

Future Circular Collider Feasibility Study Report: Volume 3, Civil Engineering, Implementation and Sustainability

Volume 3 of the FCC Feasibility Report presents studies related to civil engineering, the development of a project implementation scenario, and environmental and sustainability aspects. The report details the iterative improvements made to the civil engineering concepts since 2018, taking into account subsurface conditions, accelerator and experiment requirements, and territorial considerations. It outlines a technically feasible and economically viable civil engineering configuration that serves as the baseline for detailed subsurface investigations, construction design, cost estimation, and project implementation planning. Additionally, the report highlights ongoing subsurface investigations in key areas to support the development of an improved 3D subsurface model of the region. The report describes development of the project scenario based on the 'avoid-reduce-compensate' iterative optimisation approach. The reference scenario balances optimal physics performance with territorial compatibility, implementation risks, and costs. Environmental field investigations covering almost 600 hectares of terrain - including numerous urban, economic, social, and technical aspects - confirmed the project's technical feasibility and contributed to the preparation of essential input documents for the formal project authorisation phase. The summary also highlights the initiation of public dialogue as part of the authorisation process. The results of a comprehensive socio-economic impact assessment, which included significant environmental effects, are presented. Even under the most conservative and stringent conditions, a positive benefit-cost ratio for the FCC-ee is obtained. Finally, the report provides a concise summary of the studies conducted to document the current state of the environment.

physics.acc-ph↗
arXiv2025

The Linear Collider Facility (LCF) at CERN

In this paper we outline a proposal for a Linear Collider Facility as the next flagship project for CERN. It offers the opportunity for a timely, cost-effective and staged construction of a new collider that will be able to comprehensively map the Higgs boson's properties, including the Higgs field potential, thanks to a large span in centre-of-mass energies and polarised beams. A comprehensive programme to study the Higgs boson and its closest relatives with high precision requires data at centre-of-mass energies from the Z pole to at least 1 TeV. It should include measurements of the Higgs boson in both major production mechanisms, ee -> ZH and ee -> vvH, precision measurements of gauge boson interactions as well as of the W boson, Higgs boson and top-quark masses, measurement of the top-quark Yukawa coupling through ee ->ttH, measurement of the Higgs boson self-coupling through HH production, and precision measurements of the electroweak couplings of the top quark. In addition, ee collisions offer discovery potential for new particles complementary to HL-LHC.

hep-ex↗
arXiv2025

A Linear Collider Vision for the Future of Particle Physics

In this paper we review the physics opportunities at linear $e^+e^-$ colliders with a special focus on high centre-of-mass energies and beam polarisation, take a fresh look at the various accelerator technologies available or under development and, for the first time, discuss how a facility first equipped with a technology mature today could be upgraded with technologies of tomorrow to reach much higher energies and/or luminosities. In addition, we will discuss detectors and alternative collider modes, as well as opportunities for beyond-collider experiments and R\&D facilities as part of a linear collider facility (LCF). The material of this paper will support all plans for $e^+e^-$ linear colliders and additional opportunities they offer, independently of technology choice or proposed site, as well as R\&D for advanced accelerator technologies. This joint perspective on the physics goals, early technologies and upgrade strategies has been developed by the LCVision team based on an initial discussion at LCWS2024 in Tokyo and a follow-up at the LCVision Community Event at CERN in January 2025. It heavily builds on decades of achievements of the global linear collider community, in particular in the context of CLIC and ILC.

hep-ex↗
arXiv2023

Revisiting the averaged annihilation rate of thermal relics at low temperature

We derive a low-temperature expansion of the formula to compute the average annihilation rate $\langle \sigma v \rangle$ for dark matter in $\mathbb{Z}_2$-symmetric models, both in the absence and the presence of mass degeneracy in the spectrum near the dark matter candidate. We show that the result obtained in the absence of mass degeneracy is compatible with the analytic formulae in the literature, and that it has a better numerical behaviour for low temperatures. We also provide as ancillary files two Wolfram Mathematica notebooks which perform the two expansions at any order.

hep-ph↗
arXiv2022

Higgs Properties and Supersymmetry: Constraints and Sensitivity from the LHC to an $e^+e^-$ Collider

The study of the Higgs boson properties offers compelling perspectives for testing the effects of physics beyond the Standard Model and has deep implications for the LHC program and future colliders. Accurate determinations of the Higgs boson properties can provide us with a distinctively precise picture of the Higgs sector, set tight bounds, and predict ranges for the values of new physics model parameters. In this paper, we discuss the constraints on supersymmetry that can be derived by a determination of the Higgs boson mass and couplings. We quantify these constraints by using scans of the 19-parameter space of the so-called phenomenological minimal supersymmetric Standard Model. The fraction of scan points that can be excluded by the Higgs measurements is studied for the coupling measurement accuracies obtained in LHC Run 2 and expected for the HL-LHC program and $e^+e^-$ colliders and contrasted with those derived from missing transverse energy searches at the LHC and from dark matter experiments.

hep-ph↗
arXiv2022

Automatic extraction of one-loop Wilson coefficients in general BSM scenarios using MARTY-1.4

We present a fully automated procedure providing an easy way to perform, systematically, phenomenological analyses in flavor physics for general BSM scenarios. This procedure relies on MARTY-1.4, is model independent and requires as input only the Lagrangian of the theory. Once the Lagrangian has been defined, tree-level and one-loop Wilson coefficients can be calculated symbolically by MARTY, from which flavor observables can be computed numerically by available software programs. We focus in particular on $b\to sγ$ and the recently updated $b\to s\ell^+\ell^-$ observables which are in tension with the SM, and present a general procedure to extract the relevant one-loop coefficients, such as $C_7$, $C_7^\prime$, $C_9$ and $C_{10}$.

hep-ph↗
arXiv2021

Discriminating same-mass Neutron Stars and Black Holes gravitational wave-forms

Gravitational wave-forms from coalescences of binary black hole systems and binary neutron star systems with low tidal effects can hardly be distinguished if the two systems have similar masses. In the absence of discriminating power based on the gravitational wave-forms, the classification of sources into binary neutron stars, binary black holes and mixed systems containing a black hole and a neutron star can only be unambiguous when assuming the standard model of stellar evolution and using the fact that there exists a mass gap between neutron stars and black holes. This approach is however limited by its own assumptions: for instance the 2.6 solar mass object detected in the GW190814 event remains unclassified, and models of new physics can introduce new compact objects, like primordial black holes, which may have masses in the same range as neutron stars. Then, without an electromagnetic counterpart (kilonova), classifying mergers of compact objects without mass gap criteria remains a difficult task, unless the source is close enough. In what follows we investigate a procedure to discriminate a model between binary neutron star merger and primordial binary black hole merger by using a Bayes factor in simulated wave-forms that we superimpose to realistic detector noise.

gr-qc↗
arXiv2021

Dark matter and the early Universe: a review

Dark matter represents currently an outstanding problem in both cosmology and particle physics. In this review we discuss the possible explanations for dark matter and the experimental observables which can eventually lead to the discovery of dark matter and its nature, and demonstrate the close interplay between the cosmological properties of the early Universe and the observables used to constrain dark matter models in the context of new physics beyond the Standard Model.

hep-ph↗
arXiv2021

Semi-automated BSM model building procedures in MARTY-1.1 through a 2HDM example

MARTY is a C++ computer algebra system specialized for High Energy Physics that can calculate amplitudes, squared amplitudes and Wilson coefficients in a large variety of beyond the Standard Model scenarios up to the one-loop order. It is fully independent of any other framework and its main development guideline is generality, in order to be adapted easily to any type of model. The calculations are fully automated from the Lagrangian up to the generation of the C++ code evaluating the theoretical results (numerically, depending on the model parameters). Once a phenomenological tool chain has been set up - from a Lagrangian to observable analysis - it can be used in a model independent way leaving only model building, with MARTY, as the task to be performed by physicists. Here we present the main steps to build a general new physics model, namely gauge group, particle content, representations, replacements, rotations and symmetry breaking, using the example of a 2 Higgs Doublet Model. The sample codes that are shown for this example can be easily generalized to any Beyond the Standard Model scenario written with MARTY.

hep-ph↗
arXiv2020

Cosmological scalar fields and Big-Bang nucleosynthesis

The nature of dark matter and of dark energy which constitute more than $95\%$ of the energy in the Universe remains a great and unresolved question in cosmology. Cold dark matter can be made of an ultralight scalar field dominated by its mass term which interacts only gravitationally. The cosmological constant introduced to explain the recent acceleration of the Universe expansion can be easily replaced by a scalar field dominated by its potential. More generally, scalar fields are ubiquitous in cosmology: inflaton, dilatons, moduli, quintessence, fuzzy dark matter, dark fluid, etc. are some examples. One can wonder whether all these scalar fields are independent. The dark fluid model aims at unifying quintessence and fuzzy dark matter models with a unique scalar field. One step futher is to unify the dark fluid model with inflation. In the very early Universe such scalar fields are not strongly constrained by direct observations, but Big-Bang nucleosynthesis set constraints on scalar field models which lead to a modification on the abundance of the elements. In this talk we will present a scalar field model unifying dark matter, dark energy and inflation, and study constraints from Big-Bang nucleosynthesis on primordial scalar fields.

astro-ph.CO↗
arXiv2020

MARTY -- Modern ARtificial Theoretical phYsicist: A C++ framework automating symbolic calculations Beyond the Standard Model

Studies Beyond the Standard Model (BSM) will become more and more important in the near future with a rapidly increasing amount of data from different experiments around the world. The full study of BSM models is in general an extremely time-consuming task involving long and difficult calculations. It is in practice not possible to do exhaustive predictions in these models by hand, in particular if one wants to perform a statistical comparison with data and the SM. Here we present MARTY (Modern ARtificial Theoretical phYsicist), a new C++ framework that fully automates calculations from the Lagrangian to physical quantities such as amplitudes or cross-sections. This framework can fully simplify, automatically and symbolically, physical quantities in a very large variety of models. MARTY can also compute Wilson coefficients in effective theories. This will considerably facilitate the study of BSM models in flavor physics. Contrary to the existing public codes in this field MARTY aims to give a unique, free, open-source, powerful and user-friendly tool for high-energy physicists studying predictive BSM models, in effective or full theories up to the 1-loop level, which does not rely on any external package. With a few lines of code one can gather final expressions that may be evaluated numerically for statistical analysis. Features like automatic generation and manual edition of Feynman diagrams, comprehensive manual and documentation, clear and easy to handle user interface are amongst notable features of MARTY.

hep-ph↗
arXiv2020

MARTY, a new C++ framework for automated symbolic calculations in Beyond the Standard Model physics

Theoretical calculations Beyond the Standard Model (BSM) constitute a challenge for high energy physicists, but are necessary when searching for New Physics. The predictions of a BSM scenario need to be compared with experimental data and the Standard Model values in order to identify the model that fits better what we observe in particle colliders. BSM predictions require very involved and error prone calculations of amplitudes, cross-sections and Wilson coefficients. Calculations at the one-loop level are often necessary for these quantities since some phenomenologically important processes may not occur at tree-level, such as Flavor Changing Neutral Currents (FCNC) in flavor physics that vanish at the tree-level. One-loop calculations have to be done analytically which is very time consuming and in practice rarely done for general BSM models. Here we present MARTY, a public and open-source C++ code. MARTY is the very first independent program able to calculate automatically amplitudes, squared amplitudes and Wilson coefficients at the one-loop level for general BSM models. This type of calculations requires a computer algebra system and could only be done, up to now, using Mathematica, a commercial and closed software for symbolic manipulations. MARTY does not rely on Mathematica since it re-implements its own computer algebra system also in C++, called CSL. MARTY will considerably ease BSM studies as by automating the analytical calculations the main task of the user would be the model building part. Once interfaced with other phenomenological codes in particle physics, MARTY will be incredibly efficient to make detailed predictions for general BSM models automatically.

hep-ph↗
arXiv2020

Unifying dark matter, dark energy and inflation with a fuzzy dark fluid

Scalar fields appear in many cosmological models, in particular in order to provide explanations for dark energy and inflation, but also to emulate dark matter. In this paper, we show that it is possible for a scalar field to replace simultaneously dark matter, dark energy and inflation by assuming the existence of a non-minimal coupling to gravity, a Mexican hat potential, and a spontaneous symmetry breaking before inflation. After inflation, the scalar field behaves like a dark fluid, mimicking dark energy and dark matter, and has a dark matter behaviour similar to fuzzy dark matter.

astro-ph.CO↗
arXiv2020

Exploring Supersymmetric CP Violation after LHC Run 2 with Electric Dipole Moments and B Observables

We consider the prospects for measuring distinctive signatures of the CP-violating phases in the minimal supersymmetric extension of the Standard Model (MSSM) in light of the limits on sparticle masses from searches at the LHC. We use the CPsuperH code to evaluate model predictions and scan the parameter space using a geometric approach that maximizes CP-violating observables subject to the current upper limits on electric dipole moments (EDMs). We focus on the possible CP-violating asymmetry $A_{\rm CP}$ in $b \to s γ$ decay and on a possible CP-violating contribution to the $B_s - \overline{B}_s$ mass difference $ΔM^{NP}_{B_s}$, as well as future measurements of the EDMs of the proton, neutron and electron. We find that the current LHC and EDM limits are consistent with values of $A_{\rm CP}$, $ΔM^{NP}_{B_s}$ and the proton EDM that are measurable with the Belle-II detector, LHCb and a proposed measurement of the proton EDM using a storage ring, respectively. Measurement of a non-zero proton EDM would constrain $A_{\rm CP}$ significantly, but it and a CP-violating contribution to $ΔM^{NP}_{B_s}$ could still be measurable, along with neutron and electron EDMs. A more accurate measurement of $A_{\rm CP}$ with the current central value would favour stop and chargino masses within reach of future LHC runs as well as a potentially measurable value of $ΔM^{NP}_{B_s}$.

hep-ph↗
arXiv2019

Beyond the Standard Model Physics at the HL-LHC and HE-LHC

This is the third out of five chapters of the final report [1] of the Workshop on Physics at HL-LHC, and perspectives on HE-LHC [2]. It is devoted to the study of the potential, in the search for Beyond the Standard Model (BSM) physics, of the High Luminosity (HL) phase of the LHC, defined as $3~\mathrm{ab}^{-1}$ of data taken at a centre-of-mass energy of $14~\mathrm{TeV}$, and of a possible future upgrade, the High Energy (HE) LHC, defined as $15~\mathrm{ab}^{-1}$ of data at a centre-of-mass energy of $27~\mathrm{TeV}$. We consider a large variety of new physics models, both in a simplified model fashion and in a more model-dependent one. A long list of contributions from the theory and experimental (ATLAS, CMS, LHCb) communities have been collected and merged together to give a complete, wide, and consistent view of future prospects for BSM physics at the considered colliders. On top of the usual standard candles, such as supersymmetric simplified models and resonances, considered for the evaluation of future collider potentials, this report contains results on dark matter and dark sectors, long lived particles, leptoquarks, sterile neutrinos, axion-like particles, heavy scalars, vector-like quarks, and more. Particular attention is placed, especially in the study of the HL-LHC prospects, to the detector upgrades, the assessment of the future systematic uncertainties, and new experimental techniques. The general conclusion is that the HL-LHC, on top of allowing to extend the present LHC mass and coupling reach by $20-50\%$ on most new physics scenarios, will also be able to constrain, and potentially discover, new physics that is presently unconstrained. Moreover, compared to the HL-LHC, the reach in most observables will generally more than double at the HE-LHC, which may represent a good candidate future facility for a final test of TeV-scale new physics.

hep-ph↗