We carry out an Effective Field Theory (EFT) study of the pp →t̅ t Zh process in the final state. This process can uniquely probe the t̅ t Zh couplings arising from higher dimensional EFT operators and can also provide bounds on t̅ t Z coupling deviations. We highlight the importance of the proposed proton-proton Future Circular Collider (FCC-hh) to study this process and then perform a complete collider analysis by examining the relevant background processes. This allows us to determine the FCC-hh sensitivity to probe anomalous t̅ t Zh couplings.

Abstract We carry out an Effective Field Theory (EFT) study of the $$pp \rightarrow \bar{t} t Zh$$ p p → t ¯ t Z h process in the final state. This process can uniquely probe the $$\bar{t} t Zh$$ t ¯ t Z h couplings arising from higher dimensional EFT operators and can also provide bounds on $$\bar{t} t Z$$ t ¯ t Z coupling deviations. We highlight the importance of the proposed proton-proton Future Circular Collider (FCC-hh) to study this process and then perform a complete collider analysis by examining the relevant background processes. This allows us to determine the FCC-hh sensitivity to probe anomalous $$\bar{t} t Zh$$ t ¯ t Z h couplings.

The kaon physics programme, long heralded as a cutting-edge frontier by the European Strategy for Particle Physics, continues to stand at the intersection of discovery and innovation in high-energy physics (HEP). With its unparalleled capacity to explore new physics at the multi-TeV scale, kaon research is poised to unveil phenomena that could reshape our understanding of the Universe. This document highlights the compelling physics case, with emphasis on exciting new opportunities for advancing kaon physics not only in Europe but also on a global stage. As an important player in the future of HEP, the kaon programme promises to drive transformative breakthroughs, inviting exploration at the forefront of scientific discovery.

Data from particle physics experiments are unique and are often the result of a very large investment of resources. Given the potential scientific impact of these data, which goes far beyond the immediate priorities of the experimental collaborations that obtain them, it is imperative that the collaborations and the wider particle physics community publish and preserve sufficient information to ensure that this impact can be realised, now and into the future. The information to be published and preserved includes the algorithms, statistical information, simulations and the recorded data. This publication and preservation requires significant resources, and should be a strategic priority with commensurate planning and resource allocation from the earliest stages of future facilities and experiments.

Inclusive Higgs boson production at large transverse momentum is induced by different production channels. We focus on the leading production through gluon fusion, and perform a consistent combination of the state of the art calculations obtained in the infinite-top-mass effective theory at next-to-next-to-leading order (NNLO) and in the full Standard Model (SM) at next-to-leading order (NLO). We thus present approximate QCD predictions for this process at NNLO, and a study of the corresponding perturbative uncertainties. This calculation is then compared with those obtained with commonly used event generators, and we observe that the description of the considered kinematic regime provided by these tools is in good agreement with state of the art calculations. Finally, we present accurate predictions for other production channels such as vector boson fusion, and associated production with a gauge boson, and with a $t\bar{t}$ pair. We find that, at large transverse momentum, the contribution of other production modes is substantial, and therefore must be included for a precise theory prediction of this observable.

The interpretation of LHC data, and the assessment of possible hints of new physics, require the precise knowledge of the proton structure in terms of parton distribution functions (PDFs). We present a systematic methodology designed to determine whether and how global PDF fits might inadvertently 'fit away' signs of new physics in the high-energy tails of the distributions. We showcase a scenario for the High-Luminosity LHC, in which the PDFs may completely absorb such signs of new physics, thus biasing theoretical predictions and interpretations. We discuss strategies to single out the effects in this scenario, and disentangle the inconsistencies that stem from them. Our study brings to light the synergy between the high luminosity programme at the LHC and future low-energy non-LHC measurements of large-x sea quark distributions. The analysis code used in this work is made public so that any users can test the robustness of the signal associated to a given BSM model against absorption by the PDFs.

While sanctions in political and economic areas are now part of the standard repertoire of Western countries (not always endorsed by UN mandates), sanctions in science and culture in general are new. Historically, fundamental research as conducted at international research centers such as CERN has long been seen as a driver for peace, and the Science4Peace idea has been celebrated for decades. However, much changed with the war against Ukraine, and most Western science organizations put scientific cooperation with Russia and Belarus on hold immediately after the start of the war in 2022. In addition, common publications and participation in conferences were banned by some institutions, going against the ideal of free scientific exchange and communication. These and other points were the topics of an international virtual panel discussion organized by the Science4Peace Forum together with the "Natural Scientists Initiative - Responsibility for Peace and Sustainability" (NatWiss e.V.) in Germany and the journal "Wissenschaft und Frieden" (W&F) (see the Figure). Fellows from the Hamburg Institute for Peace Research and Security Policy (IFSH), scientists collaborating with the large physics research institutes DESY and CERN, as well as from climate and futures researchers were represented on the panel. In this Dossier we document the panel discussion, and give additional perspectives. The authors of the individual sections present their personal reflections, which should not be taken as implying that they are endorsed by the Science4Peace Forum or any other organizations. It is regrettable that some colleagues who expressed support for this document felt that it would be unwise for them to co-sign it.

In this white paper for the 2021 Snowmass process, we give a description of the proposed Future Circular Collider (FCC) project and its physics program. The paper summarizes and updates the discussion submitted to the European Strategy on Particle Physics. After construction of an approximately 90 km tunnel, an electron-positron collider based on established technologies allows world-record instantaneous luminosities at center-of-mass energies from the Z resonance up to tt thresholds, enabling a rich set of fundamental measurements including Higgs couplings determinations at the sub percent level, precision tests of the weak and strong forces, and searches for new particles, including dark matter, both directly and via virtual corrections or mixing. Among other possibilities, the FCC-ee will be able to (i) indirectly discover new particles coupling to the Higgs and/or electroweak bosons up to scales around 7 and 50 TeV, respectively; (ii) perform competitive SUSY tests at the loop level in regions not accessible at the LHC; (iii) study heavy-flavor and tau physics in ultra-rare decays beyond the LHC reach, and (iv) achieve the best potential in direct collider searches for dark matter, sterile neutrinos, and axion-like particles with masses up to around 90 GeV. The tunnel can then be reused for a proton-proton collider, establishing record center-of-mass collision energy, allowing unprecedented reach for direct searches for new particles up to the around 50 TeV scale, and a diverse program of measurements of the Standard Model and Higgs boson, including a precision measurement of the Higgs self-coupling, and conclusively testing weakly-interacting massive particle scenarios of thermal relic dark matter.

We present a measurement of the W boson mass in W-->e(nu) decays using 1 fb-1 of data collected with the D0 detector during Run II of the Fermilab Tevatron collider. With a sample of 499830 W-->e(nu) candidate events, we measure M(W)=80.401+/-0.043 GeV. This is the most precise measurement from a single experiment.

The Future Circular Collider (FCC) study was launched as a worldwide international collaboration hosted by CERN with the ultimate goal of pushing the energy frontier far beyond the LHC. FCC covers two accelerators, namely an energy-frontier hadron collider (FCC-hh) and a highest luminosity, high-energy lepton collider (FCC-ee) serving as electroweak Higgs factory, as a possible first stage. The mass of particles that could be either directly produced at FCC-hh or indirectly detected at FCC-ee is increased by an order of magnitude, relative to today's reach, and the subatomic distances that can be resolved are decreased in the same proportion. Importantly, FCC-hh and FCC-ee share the same ~100 km tunnel infrastructure. This paper focuses on the FCC-hh, summarising its key features, such as accelerator design, performance reach, and underlying technologies. The discussion is based on the 2019 conceptual design report (CDR) [1], which represents a study milestone, but also describes more recent design activities and indicates future directions.

The Future Circular Collider (FCC) study was launched as a world-wide international collaboration hosted by CERN. Its goal is to push the field to the next energy frontier beyond LHC, increasing by an order of magnitude the mass of particles that could be directly produced, and decreasing by an order of magnitude the subatomic distances to be studied. The FCC study covers two accelerators, namely, an energy-frontier hadron collider (FCC-hh) and a highest luminosity, high-energy lepton collider (FCC-ee). Both rings are hosted in the same 100 km tunnel infrastructure, replicating the CERN strategy for LEP and LHC, i.e. developing a lepton and a hadron ring sharing the same tunnel. This paper is devoted to the FCC-hh and summarizes the key features of the FCC-hh accelerator design, performance reach, and underlying technologies. The material presented in this paper builds on the conceptual design report published in 2019, and extends it, including also the progress made and the results achieved since then.

One of the main theoretical systematics in studies of final states with large jet multiplicities at high-energy hadron colliders is associated with the merging of QCD parton showers and hard-scattering matrix elements. We present a method to incorporate the physics of transverse momentum recoils due to initial-state shower evolution into multi-jet merging algorithms by using the concept of transverse momentum dependent (TMD) distributions and the associated parton branching. We investigate the dependence on the merging scale and illustrate the impact of the new method at the level of both exclusive and inclusive final-state observables by studying differential jet rates, transverse momentum spectra and multiplicity distributions, using vector boson + jets events at the LHC as a case study.

CERN-ACC-2018-004517 March 2019Higgs and Electro-weak symmetry breaking at the FCC-hhL. Borgonovi∗, S. Braibant∗, B. Di Micco†, E. Fontanesi∗, P. Harris‡, C. Helsens§, D. Jamin§,M.L. Mangano§, G. Ortona¶, M. Selvaggi1)§, A. Sznajder‖, M. Testa¶, M. Verducci¶On behalf of the FCC-hh Collaboration∗Universita di Bologna, Italy,†Universita degli Studi Roma Tre, Italy,‡Massachusetts Institute of Technology (MIT), Cambridge, USA,§European Organization for Nuclear Research (CERN), Geneva, Switzerland,¶Laboratoire Leprince-Ringuet, Ecole Polytechnique (LLR), Palaiseau, France,‖Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, BrazilAbstractThe future circular hadron-hadron collider FCC-hh is expected to produce collisions at thecenter of mass energy of√s=100 TeV and to deliver an integrated luminosity of 30 ab−1.The Higgs-self coupling will be measured with a 5% precision via double Higgs production.Tens of billions of Higgs bosons will be produced at the FCC-hh. Such large statisticswill allow for a wide range of possibilities in the realm of precision Higgs measurements.Several Higgs couplings will be measured to a percent level precision, including the secondgeneration muon yukawa coupling. The Higgs to invisible branching fraction will be probedto a level of few 10−4and the rate of longitudinally polarized vector bosons produced invector boson scattering will be measured with 2% precision.

The theoretical description of the physics of multi-jets in hadronic collisions at high energies is based on “merging” methods, which combine short-timescale production of jets with long-timescale evolution of partonic showers. We point out potential implications of the evolution of transverse momentum dependent (TMD) distributions on the structure of multi-jet states at high energies, and in particular on the theoretical systematics associated with multi-jet merging. To analyze this, we propose a new merging methodology, and illustrate its impact by comparing our theoretical results with experimental measurements for Z-boson + jets production at the Large Hadron Collider (LHC).

— We discuss implications of the evolution of transverse momentum dependent (TMD) parton distributions on the structure of multi-jet states at high energies. In particular we analyze the theoretical systematics associated with multi-jet merging. We introduce a new merging methodology incorporating TMDs, illustrate its main features and present a comparison of our theoretical results with experimental measurements for Z-boson + jets production at the Large Hadron Collider (LHC).

We review the main software and computing challenges for the Monte Carlo physics event generators used by the LHC experiments, in view of the High-Luminosity LHC (HL-LHC) physics programme. This paper has been prepared by the HEP Software Foundation (HSF) Physics Event Generator Working Group as an input to the LHCC review of HL-LHC computing, which has started in May 2020.

We discuss the origin and size of potential uncertainties arising in the estimate of cross sections for the production of multiparticle final states induced by QCD instantons at the LHC.

We address the potential of measurements with boosted single-top final states at the high-luminosity LHC (HL-LHC) and possible future hadron colliders: the high-energy LHC (HE-LHC), and the future circular collider (FCC). As new physics examples to assess the potential, we consider the search for tbW anomalous couplings and for a weakly-coupled W ' boson. The FCC would improve by a factor of two the sensitivity to anomalous couplings of the HL-LHC. For W ' bosons, the FCC is sensitive to W ' couplings 2-5 times smaller than the HL-LHC in the mass range 2-4 TeV, and to masses up to 30 TeV in the case of Standard Model-like couplings.

This note addresses the requirements that should satisfy a detector operating in the FCChh environment in order to maximise its physics potential. Such a detector will operate in challenging conditions, and will be required to respond optimally in a wide energy range to fulfill a physics programme ranging from the electro-weak scale to the multi-tens of TeV energy frontier. Extreme granularity, excellent energy-momentum resolution beyond the LHC detectors, together will novel algorthims will be needed to achieve optimal object reconstruction and identification. c © 2020 CERN for the benefit of the FCC Collaboration. Reproduction of this article or parts of it is allowed as specified in the CC-BY-4.0 license. clement.helsens@cern.ch michelangelo.mangano@cern.ch michele.selvaggi@cern.ch