Report of the 2021 U.S. Community Study on the Future of Particle Physics (Snowmass 2021) Summary Chapter

Butler, J. N.; Chivukula, R. Sekhar; Gouvêa, André de; Han, Tao; Kim, Young-Kee; Cushman, P.; Farrar, Glennys R.; Kolomensky, Yury; Nagaitsev, Sergei; Yunes, Nicolás; Gourlay, S.A.; Raubenheimer, T.O.; Shiltsev, Vladimir; Assamagan, K.; Quinn, B.; Elvira, V. D.; Gottlieb, Steven; Nachman, B. P.; Chou, A.; Soares-Santos, M.; Tait, Tim M. P.; Narain, M.; Reina, Laura; Tricoli, A.; Barbeau, P. S.; Merkel, P.; Zhang, Jinlong; Huber, Patrick; Scholberg, K.; Worcester, E.; Artuso, M.; Bernstein, R. H.; Petrov, Alexey A.; Craig, Nathaniel; Csáki, Csaba; El‐Khadra, Aida X.; Baudis, L.; Hall, J.; Lesko, K. T.; Orrell, J. L.; Gonski, Julia Lynne; Psihas, F.; Simon, Sara M.

doi:10.48550/arxiv.2301.06581

“…The terms proportional to cos 2 ξ and sin 2 ξ originate from the modulus square of diagrams where the Higgs is radiated off a top quark, such as figure 1(a). The terms independent of ξ are from the square of diagrams where the Higgs is radiated off an internal Z-boson, 3 proportional to cos ξ are due to interference between diagrams where the Higgs is radiated off of a top quark or Z-boson. Hence, for t th production we use the general parameterization,…”

Section: Cp Admixturesmentioning

confidence: 99%

“…One of the major goals of the Large Hadron Collider (LHC) and future collider programs is to measure the properties of the Higgs boson [1][2][3][4]. Since the top quark is the heaviest particle in the Standard Model (SM) and has the strongest coupling to the Higgs, processes involving the top quark Yukawa coupling provide us an ideal place to study the Higgs properties.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Probing the CP structure of the top quark Yukawa at the future muon collider

Cassidy,

Dong,

Kong

et al. 2024

J. High Energ. Phys.

2

0

View full text Add to dashboard Cite

We study the top-Higgs coupling with a CP violating phase ξ at a future multi-TeV muon collider. We focus on processes that are directly sensitive to the top quark Yukawa coupling: $$ t\overline{t}h $$ t t ¯ h , tbhμν, and $$ t\overline{t} h\nu \overline{\nu} $$ t t ¯ hν ν ¯ with $$ h\to b\overline{b} $$ h → b b ¯ and semileptonic top decays. At different energies, different processes dominate the cross section, providing complementary information. At and above an energy of $$ \mathcal{O}(10) $$ O 10 TeV, vector boson fusion processes dominate. As we show, in the Standard Model there is destructive interference in the vector boson fusion processes $$ t\overline{t} h\nu \overline{\nu} $$ t t ¯ hν ν ¯ and tbhμν between the top quark Yukawa and Higgs-gauge boson couplings. A CP-violating phase changes this interference, and the cross section measurement is very sensitive to the size of the CP-violating angle. Although we find that the cross sections are measured to $$ \mathcal{O}\left(50\%\right) $$ O 50 % statistical uncertainty at 1σ, a 10 and 30 TeV muon collider can bound the CP-violating angle |ξ| ≲ 9.0° and |ξ| ≲ 5.4°, respectively. However, cross section measurements are insensitive to the sign of the CP-violating angle. To determine that the coupling is truly CP violating, observables sensitive to CP-violation must be measured. We find in the $$ t\overline{t}h $$ t t ¯ h process the azimuthal angle between the $$ t+\overline{t} $$ t + t ¯ plane and the initial state muon+Higgs plane shows good discrimination for ξ = ±0.1π. For the tbhμν and $$ t\overline{t} h\nu \overline{\nu} $$ t t ¯ hν ν ¯ processes, the operator proportional to $$ \left({\overrightarrow{p}}_{\mu}\times {\overrightarrow{p}}_h\right) $$ p → μ × p → h · $$ {\overrightarrow{p}}_t $$ p → t is sensitive to the sign of CP phase ξ. From these observables, we construct asymmetry parameters that show good distinction between different values and signs of the CP violating angle.

show abstract

“…The Snowmass 2021 long-range exercise [4] is structured around ten working groups (or "Frontiers") meant to encompass all the activities of the particle physics community. Cosmic-ray physics belongs to the Cosmic Frontier (CF) [5] and more specifically to the topical group 7 (CF7) entitled "Cosmic Probes of Fundamental Physics" [6].…”

Section: The Snowmass Uhecr White Papermentioning

confidence: 99%

“Ultra-High-Energy Cosmic-Rays (UHECR): at the Intersection of the Cosmic and Energy Frontiers” -- Overview of the Snowmass UHECR white paper and roadmap

Sarazin¹

2023

Proceedings of 38th International Cosmic Ray Conference — PoS(ICRC2023)

View full text Add to dashboard Cite

As part of the US "Snowmass" community planning exercise, the UHECR community has come together to write a comprehensive white paper discussing the recent progress and open questions in the field, as they relate to the overarching goals of particle and astroparticle physics. The document outlines strategies and recommendations for answering these questions over the next two decades. It also proposes an integrated timeline, which considers the progress expected to be achieved by the upgraded Pierre Auger Observatory and Telescope Array experiment in this decade, and the need for a set of complementary next-generation experiments combining high-accuracy measurements (GCOS, IceCube-Gen2 with its surface array) and very high exposure at the highest energies (GRAND, POEMMA) in the next decade. The resulting document, entitled "Ultra-High Energy Cosmic-Rays: at the Intersection of the Cosmic and Energy Frontiers", appears as a special issue of Astroparticle Physics (Astropart. Phys. 149 (2023) 102819 -arXiv:2205.05845). This contribution provides a summary of the document with a focus on (selected) recommendations and proposed roadmap.

show abstract

“…To address this situation, our community needs to put forward an ambitious program to discover the now-unknown fundamental interactions that underlie the SM. The community [6][7][8][9][10][11] is converging globally on a program with two essential elements:…”

Section: Introductionmentioning

confidence: 99%

Status and future plans for C³ R&D

Nanni,

Breidenbach,

Li

et al. 2023

View full text Add to dashboard Cite

C3 is an opportunity to realize an e + e - collider for the study of the Higgs boson at √s = 250 GeV, with a well defined upgrade path to 550 GeV while staying on the same short facility footprint [2,3]. C3 is based on a fundamentally new approach to normal conducting linear accelerators that achieves both high gradient and high efficiency at relatively low cost. Given the advanced state of linear collider designs, the key system that requires technical maturation for C3 is the main linac. This paper presents the staged approach towards a facility to demonstrate C3 technology with both Direct (source and main linac) and Parallel (beam delivery, damping ring, ancillary component) R&D. The primary goal of the C3 Demonstration R&D Plan is to reduce technical and cost risk by building and operating the key components of C3 at an adequate scale. This R&D plan starts with the engineering design, and demonstration of one cryomodule and will culminate in the construction of a 3 cryomodule linac with pre-production prototypes. This R&D program would also demonstrate the linac rf fundamentals including achievable gradient and gradient stability over a full electron bunch train and breakdown rates. It will also investigate beam dynamics including energy spread, wakefields, and emittance growth. This work will be critical to confirm the suitability of the C3 beam parameters for the physics reach and detector performance in preparation for a Conceptual Design Report (CDR), as well as for follow-on technology development and industrialization. The C3 Demonstration R&D Plan will open up significant new scientific and technical opportunities based on development of high-gradient and high-efficiency accelerator technology. It will push this technology to operate both at the GeV scale and mature the technology to be reliable and provide high-brightness electron beams. The timeline for progressing with C3 technology development will be governed by practical limitations on both the technical progress and resource availability. It consists of four stages: Stage 0) Ongoing fundamental R&D on structure prototypes, damping and vibrations. Stage 1) Advancing the engineering maturity of the design and developing start-to-end simulations including space-charge and wakefield effects. This stage will include testing of strucutres operating at cryogenic temperatures. Beam tests would be performed with high beam current to test full beam loading. Stage 2) Production and testing of the first cryomodule at cryogenic temperatures. This would provide sufficient experimental data to compile a CDR and it is anticipated for Stage 2 to last 3 years and to culminate with the transport of photo-electrons through the first cryomodule. Stage 3) Updates to the engineering design of the cryomodules, production of the second and third cryomodule and their installation. Lower charge and lower emittance beams will be used to investigate emittance growth. The successful full demonstration of the 3 cryomodules to deliver up to a 3 GeV beam and achieve the C3five gradient will allow a comprehensive and robust evaluation of the technical design of C3 as well as mitigate technical, schedule, and cost risks required to proceed with a Technical Design Report (TDR).

show abstract

Report of the 2021 U.S. Community Study on the Future of Particle Physics (Snowmass 2021) Summary Chapter

Cited by 3 publications

References 13 publications

Probing the CP structure of the top quark Yukawa at the future muon collider

Probing the CP structure of the top quark Yukawa at the future muon collider

“Ultra-High-Energy Cosmic-Rays (UHECR): at the Intersection of the Cosmic and Energy Frontiers” -- Overview of the Snowmass UHECR white paper and roadmap

Status and future plans for C³ R&D

Contact Info

Product

Resources

About

Report of the 2021 U.S. Community Study on the Future of Particle Physics (Snowmass 2021) Summary Chapter

Cited by 3 publications

References 13 publications

Probing the CP structure of the top quark Yukawa at the future muon collider

Probing the CP structure of the top quark Yukawa at the future muon collider

“Ultra-High-Energy Cosmic-Rays (UHECR): at the Intersection of the Cosmic and Energy Frontiers” -- Overview of the Snowmass UHECR white paper and roadmap

Status and future plans for C3 R&D

Contact Info

Product

Resources

About

Status and future plans for C³ R&D