arXiv subjects

Massimo Casarsa

Publications and source records attributed to Massimo Casarsa.

At least 19 recordsLinked to original sources

arXiv2026

Prospects for precision Higgs boson measurements at a 10 TeV muon collider

A 10 TeV muon collider offers a powerful environment for precision studies of the Higgs sector through its large vector-boson-fusion production rates. This review presents projected sensitivities to single- and double-Higgs production cross sections, the Higgs boson mass, and the trilinear Higgs self-coupling. The projections are obtained from detailed simulations of the MUSIC detector, including machine-induced background, for a baseline configuration of two experiments, each collecting an integrated luminosity of 10 $\mathrm{ab}^{-1}$. The $H\to b\bar{b}$ and $H\to WW^\ast$ production cross sections can be measured with statistical precisions of 0.18% and 0.35%, respectively, while precisions of 2.6%, 4.2%, and 6.9% are expected for $H\to\gamma\gamma$, $H\to ZZ^\ast$, and $H\to\mu^+\mu^-$. Combining the $H\to b\bar{b}$, $H\to\gamma\gamma$, and $H\to\mu^+\mu^-$ channels yields an expected Higgs boson mass precision of about 19 MeV. Double-Higgs production can be measured with statistical precisions of 4.2% in the $HH\to b\bar{b}b\bar{b}$ channel and 14% in the $HH\to b\bar{b}WW^\ast$ channel. Using the $HH\to b\bar{b}b\bar{b}$ channel, the trilinear Higgs self-coupling can be determined with an expected precision of about 5%. These results demonstrate the potential of a high-energy muon collider for precision Higgs physics.

hep-ex↗

arXiv2026

Higgs Physics at a $\sqrt{s} = 10$ TeV Muon Collider

This contribution discusses the physics potential of a future muon collider operating at a center-of-mass energy of $\sqrt{s} = 10$ TeV for precision studies in the Higgs sector. Using a detailed detector simulation that incorporates the dominant sources of machine-induced background, the expected sensitivity to key Higgs processes is evaluated. These include the measurement of production cross sections for $H\to b\bar{b}$, $H\to WW^*$, and double-Higgs production $H\!H\to b\bar{b}b\bar{b}$. A central focus of the study is the determination of the Higgs boson trilinear self-coupling, a critical parameter for understanding the structure of the Higgs potential and electroweak symmetry breaking. The analysis is based on the MUSIC multi-purpose detector concept, specifically optimized for the muon collider environment, and assumes an integrated luminosity of $10$ ab$^{-1}$ collected over five years. The results presented highlight the exceptional prospects of a multi-TeV muon collider for exploring the Higgs potential with a level of precision unattainable by any other proposed future collider within a comparable timeframe.

hep-ex↗

arXiv2026

MUSIC: a detector concept for 10 TeV $\mathbf{μ^+μ^-}$ collisions

The full exploitation of the physics potential of a multi-TeV muon collider will ultimately lie in the detector's ability to cope with unprecedented levels of machine-induced backgrounds. This contribution introduces the MUSIC (MUon System for Interesting Collisions) detector concept and presents its performance in the context of $\sqrt{s}$ = 10 TeV muon-antimuon collisions. The MUSIC detector is designed to mitigate machine-induced background effects while maintaining high efficiency and accuracy in the reconstruction of physics events, in particular in the Higgs boson sector and in the search for new physics. It features an all-silicon tracking system, a semi-homogeneous lead-fluorite crystal electromagnetic calorimeter, an iron-scintillator sampling hadronic calorimeter, and a superconducting magnet providing a 5 T magnetic field. Detailed detector simulations, accounting for the dominant machine-induced backgrounds, demonstrate promising performance in track, muon, photon, electron, and jet reconstruction, as well as jet flavor identification, highlighting the detector's strong potential for high-energy muon collider experiments.

hep-ex↗

arXiv2025

MUSIC: A Multi-Purpose Detector Concept for Physics at the 10 TeV Muon Collider

This work presents a proof of concept for MUSIC, a multi-purpose detector conceived for high-precision and ultra-high-energy physics studies in the challenging environment of $\sqrt{s}=10$ TeV muon-antimuon collisions. The detector features a central tracking system, electromagnetic and hadronic calorimeters, and dedicated muon detectors. This paper outlines the main design elements of each subdetector, with an emphasis on the effects of machine-induced backgrounds and the reconstruction strategies employed for key physics objects. Performance results for electrons, photons, muons, and jets are reported, and studies of jet flavour identification are discussed.

hep-ex↗

arXiv2025

MuCol Milestone Report No. 7: Consolidated Parameters

This document is comprised of a collection of consolidated parameters for the key parts of the muon collider. These consolidated parameters follow on from the October 2024 Preliminary Parameters Report. Attention has been given to a high-level consistent set of baseline parameters throughout all systems of the complex, following a 10 TeV center-of-mass design. Additional details of the designs contributing to this baseline design are featured in the appendix. Likewise, explorative variations from this baseline set can be found in the appendix. The data is collected from a collaborative spreadsheet and transferred to overleaf.

physics.acc-ph↗

arXiv2025

The Muon Collider

Muons offer a unique opportunity to build a compact high-energy electroweak collider at the 10 TeV scale. A Muon Collider enables direct access to the underlying simplicity of the Standard Model and unparalleled reach beyond it. It will be a paradigm-shifting tool for particle physics representing the first collider to combine the high-energy reach of a proton collider and the high precision of an electron-positron collider, yielding a physics potential significantly greater than the sum of its individual parts. A high-energy muon collider is the natural next step in the exploration of fundamental physics after the HL-LHC and a natural complement to a future low-energy Higgs factory. Such a facility would significantly broaden the scope of particle colliders, engaging the many frontiers of the high energy community. The last European Strategy for Particle Physics Update and later the Particle Physics Project Prioritisation Panel in the US requested a study of the muon collider, which is being carried on by the International Muon Collider Collaboration. In this comprehensive document we present the physics case, the state of the work on accelerator design and technology, and propose an R\&D project that can make the muon collider a reality.

physics.acc-ph↗

arXiv2024

A space-time tracking algorithm for high occupancy events at future colliders

We propose to explore the potential advantages of a new class of tracking algorithms loosely inspired by the Hough transform concept and where we include the time of arrival of each hit as an additional coordinate to be treated in the same way as a spatial coordinate. A remarkable property of this algorithm is that the execution time is proportional to the total number of hits to be processed, making it particularly attractive for high occupancy situations expected at future colliders. The particular structure of the algorithm also lends itself naturally to parallel hardware implementations which, combined to its intrinsic flexibility, should provide a powerful tool for triggering at future colliders. To probe the effectiveness of the algorithm, we apply it to a quasi-realistic simulated environment of a possible future muon collider experiment and report the performance.

hep-ex↗

arXiv2024

MuCol Milestone Report No. 5: Preliminary Parameters

This document is comprised of a collection of updated preliminary parameters for the key parts of the muon collider. The updated preliminary parameters follow on from the October 2023 Tentative Parameters Report. Particular attention has been given to regions of the facility that are believed to hold greater technical uncertainty in their design and that have a strong impact on the cost and power consumption of the facility. The data is collected from a collaborative spreadsheet and transferred to overleaf.

physics.acc-ph↗

arXiv2024

Experimentation at a muon collider

Experimental activities involving multi-TeV muon collisions are a relatively recent endeavor. The community has limited experience in designing detectors for lepton interactions at center-of-mass energies of 10 TeV and beyond. This review provides a short overview of the machine characteristics and outlines potential sources of beam-induced background that could impact the detector performance. The strategy for mitigating the effects of beam-induced background on the detector at $\sqrt{s}=3$ TeV is discussed, focusing on the machine-detector interface, detector design, and the implementation of reconstruction algorithms. The physics potential at this center-of-mass energy is evaluated using a detailed detector simulation that incorporates the effects of beam-induced background. This evaluation concerns the Higgs boson couplings and the Higgs field potential sensitivity, that then are used to get confidence on the expectations at 10 TeV. The physics and detector requirements for an experiment at $\sqrt{s}=10$ TeV, outlined here, form the foundation for the initial detector concept at that center-of-mass energy .

hep-ex↗

arXiv2024

Higgs Physics at a $\sqrt{s}=3$ TeV Muon Collider with detailed detector simulation

The Muon Collider is one of the most promising future collider facilities with the potential to reach multi-TeV center-of-mass energy and high luminosity. Due to the significant Higgs boson production cross section in muon collisions at these high energies, the collider can be considered a Higgs factory. It holds the capability to significantly advance our understanding of the Higgs sector to an unprecedented level of precision. However, the presence of beam-induced background resulting from the decay of the beam muons poses unique challenges for detector development and event reconstruction. In this paper, the prospects for various measurements of the Higgs boson production cross sections at a $\sqrt{s}=3$ TeV collider are presented using a detailed detector simulation in a realistic environment. The study demonstrates the feasibility of achieving high precision measurements of the Higgs boson production cross sections with the current state-of-the-art detector design. In addition, the paper discusses the detector requirements necessary for obtaining such resolutions and for measuring the Higgs trilinear self-coupling.

hep-ex↗

arXiv2023

Towards a Muon Collider

A muon collider would enable the big jump ahead in energy reach that is needed for a fruitful exploration of fundamental interactions. The challenges of producing muon collisions at high luminosity and 10 TeV centre of mass energy are being investigated by the recently-formed International Muon Collider Collaboration. This Review summarises the status and the recent advances on muon colliders design, physics and detector studies. The aim is to provide a global perspective of the field and to outline directions for future work.

physics.acc-ph↗

arXiv2022

Charged Particle Tracking in Real-Time Using a Full-Mesh Data Delivery Architecture and Associative Memory Techniques

We present a flexible and scalable approach to address the challenges of charged particle track reconstruction in real-time event filters (Level-1 triggers) in collider physics experiments. The method described here is based on a full-mesh architecture for data distribution and relies on the Associative Memory approach to implement a pattern recognition algorithm that quickly identifies and organizes hits associated to trajectories of particles originating from particle collisions. We describe a successful implementation of a demonstration system composed of several innovative hardware and algorithmic elements. The implementation of a full-size system relies on the assumption that an Associative Memory device with the sufficient pattern density becomes available in the future, either through a dedicated ASIC or a modern FPGA. We demonstrate excellent performance in terms of track reconstruction efficiency, purity, momentum resolution, and processing time measured with data from a simulated LHC-like tracking detector.

hep-ex↗

arXiv2022

Simulated Detector Performance at the Muon Collider

In this paper we report on the current status of studies on the expected performance for a detector designed to operate in a muon collider environment. Beam-induced backgrounds (BIB) represent the main challenge in the design of the detector and the event reconstruction algorithms. The current detector design aims to show that satisfactory performance can be achieved, while further optimizations are expected to significantly improve the overall performance. We present the characterization of the expected beam-induced background, describe the detector design and software used for detailed event simulations taking into account BIB effects. The expected performance of charged-particle reconstruction, jets, electrons, photons and muons is discussed, including an initial study on heavy-flavor jet tagging. A simple method to measure the delivered luminosity is also described. Overall, the proposed design and reconstruction algorithms can successfully reconstruct the high transverse-momentum objects needed to carry out a broad physics program.

hep-ex↗

arXiv2022

Muon Collider Physics Summary

The perspective of designing muon colliders with high energy and luminosity, which is being investigated by the International Muon Collider Collaboration, has triggered a growing interest in their physics reach. We present a concise summary of the muon colliders potential to explore new physics, leveraging on the unique possibility of combining high available energy with very precise measurements.

hep-ph↗

arXiv2022

The physics case of a 3 TeV muon collider stage

In the path towards a muon collider with center of mass energy of 10 TeV or more, a stage at 3 TeV emerges as an appealing option. Reviewing the physics potential of such muon collider is the main purpose of this document. In order to outline the progression of the physics performances across the stages, a few sensitivity projections for higher energy are also presented. There are many opportunities for probing new physics at a 3 TeV muon collider. Some of them are in common with the extensively documented physics case of the CLIC 3 TeV energy stage, and include measuring the Higgs trilinear coupling and testing the possible composite nature of the Higgs boson and of the top quark at the 20 TeV scale. Other opportunities are unique of a 3 TeV muon collider, and stem from the fact that muons are collided rather than electrons. This is exemplified by studying the potential to explore the microscopic origin of the current $g$-2 and $B$-physics anomalies, which are both related with muons.

hep-ph↗

arXiv2022

Mono-chromatic single photon events at the muon collider

The cross section for lepton pair annihilation into a photon and a dark photon or an axion-like particle is constant for large center-of-mass energies because some of the portal operators coupling Standard Model and dark sector are proportional to the energy. Feebly coupled though they are, these portal operators will be enhanced by the large center-of-mass energy made available by a muon collider and thus provide the ideal example of possible physics beyond the Standard Model to be studied with such a machine. We discuss the characteristic signature of the presence of these operators: mono-chromatic single photon events for the two benchmarks of having center-of-mass energies of 3 and 10 TeV and integrated luminosity of, respectively, 1 and 10 ab$^{-1}$. We find that an effective scale of the portal operator as large as $Λ=112$ TeV for an axion-like particle and $Λ=141$ TeV for a dark photon can be separated from the background with a confidence level of 95% in the first benchmark; these interaction scales can be raised to $Λ=375$ TeV and $Λ=459$ TeV in the case of the second benchmark. The signal for the pseudo scalar particle can be distinguished from that of the spin-1 with about 500 events. The response of the detector to high-energy photons is examined.

hep-ph↗

arXiv2022

Promising Technologies and R&D Directions for the Future Muon Collider Detectors

Among the post-LHC generation of particle accelerators, the muon collider represents a unique machine with capability to provide very high energy leptonic collisions and to open the path to a vast and mostly unexplored physics programme. However, on the experimental side, such great physics potential is accompanied by unprecedented technological challenges, due to the fact that muons are unstable particles. Their decay products interact with the machine elements and produce an intense flux of background particles that eventually reach the detector and may degrade its performance. In this paper, we present technologies that have a potential to match the challenging specifications of a muon collider detector and outline a path forward for the future R&D efforts.

physics.ins-det↗

arXiv2020

Detector and Physics Performance at a Muon Collider

A muon collider represents the ideal machine to reach very high center-of-mass energies and luminosities by colliding elementary particles. This is the result of the low level of beamstrahlung and synchrotron radiation compared to linear or circular electron-positron colliders. In contrast with other lepton machines, the design of a detector for a multi-TeV muon collider requires the knowledge of the interaction region due to the presence of a large amount of background induced by muon beam decays. The physics reaches can be properly evaluated only when the detector performance is determined. In this work, the background generated by muon beams of $750$ GeV is characterized and the performance of the tracking system and the calorimeter detector are illustrated. Solutions to minimize the effect of the beam-induced background are discussed and applied to obtain track and jet reconstruction performance. The $μ^+μ^-\to Hν\barν\to b\bar b ν\barν$ process is fully simulated and reconstructed to demonstrate that physics measurements are possible in this harsh environment. The precision on Higgs boson coupling to $b\bar b$ is evaluated for $\sqrt{s}=1.5$, 3, and 10 TeV and compared to other proposed machines.

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