Publications

I am a theoretical physicist and my work has focused on building extensions of the Standard Model of particle physics and the experimental phenomena that could be used to discover them.

2026

Understanding the quantized angular momentum of rotating Q-balls

Benjamin DeVries^‡, Fabrizio Vassallo, and Christopher B. Verhaaren

J. High Energy Phys. 2026, 108 (2026).
Review of neutral naturalness

Brian Batell, Matthew Low, Ethan T. Neil, and Christopher B. Verhaaren

Phys. Rep.-Rev. Sec. Phys. Lett. 1165, 1-49 (2026).

2025

Future Circular Collider Feasibility Study Report

M. Benedikt, F. Zimmermann, B. Auchmann, W. Bartmann, J. P. Burnet, C. Carli, … C. B. Verhaaren, … (1,468 other authors)

Eur. Phys. J. C 85, 1468 (2025).
Future circular collider feasibility study report: Volume 2 Accelerators, technical infrastructure and safety

M. Benedikt, F. Zimmermann, B. Auchmann, W. Bartmann, J. P. Burnet, C. Carli, … C. B. Verhaaren, … (1,466 other authors)

Eur. Phys. J. Spec. Top., (2025).
Extended color twin Higgs

Brian Batell, Thomas Cochran^‡, Logan Page^†, and Christopher B. Verhaaren

J. High Energy Phys. 2025, 92 (2025).
Future Circular Collider Feasibility Study Report: Volume 3 Civil Engineering, Implementation and Sustainability

M. Benedikt, F. Zimmermann, B. Auchmann, W. Bartmann, J. P. Burnet, C. Carli, … C. B. Verhaaren, … (754 other authors)

Eur. Phys. J. Spec. Top., (2025).
Geometrizing the anomaly

Joshua Newey^‡, John Terning, and Christopher B. Verhaaren

J. High Energy Phys. 2025, 5 (2025).
Visible collider signals of natural quirks

Joshua Forsyth^†, Matthew Low, Carson Tenney^‡, and Christopher B. Verhaaren

Phys. Rev. D 111 (11), 115021 (2025).

2024

Schwinger vs Coleman: Magnetic charge renormalization

Joshua Newey^†, John Terning, and Christopher B. Verhaaren

J. High Energy Phys. 11, 75 (2024).
Slowly rotating Q-balls

Yahya Almumin, Julian Heeck, Arvind Rajaraman, and Christopher B. Verhaaren

Eur. Phys. J. C 84 (4), 364 (2024).
Q-balls in anti-de Sitter space

Arvind Rajaraman, Alexander Stewart, and Christopher B. Verhaaren

Phys. Rev. D 109 (8), 086003 (2024).

2022

Theory, phenomenology, and experimental avenues for dark showers: a Snowmass 2021 report

Guillaume Albouy, Jared Barron, Hugues Beauchesne, Elias Bernreuther, Marcella Bona, Cesare Cazzaniga, … Christopher B. Verhaaren, … (47 other authors)

Eur. Phys. J. C 82 (12), 1132 (2022).
Simulating glueball production in N_f = 0 QCD

David Curtin, Caleb Gemmell, and Christopher B. Verhaaren

Phys. Rev. D 106 (7), 075015 (2022).
Searches for long-lived particles at the future FCC-ee

C. B. Verhaaren, J. Alimena, M. Bauer, P. Azzi, R. Ruiz, M. Neubert, … (13 other authors)

Front. Physics 10, 967881 (2022).
Excited Q-balls

Yahya Almumin, Julian Heeck, Arvind Rajaraman, and Christopher B. Verhaaren

Eur. Phys. J. C 82 (9), 801 (2022).

2021

Twin quark dark matter from cogenesis

Can Kilic, Christopher B. Verhaaren, and Taewook Youn

Phys. Rev. D 104 (11), 116018 (2021).
Proca Q-balls and Q-shells

Julian Heeck, Arvind Rajaraman, Rebecca Riley, and Christopher B. Verhaaren

J. High Energy Phys. 2021 (10), 103 (2021).
Ubiquity of gauged Q-shells

Julian Heeck, Arvind Rajaraman, and Christopher B. Verhaaren

Phys. Rev. D 104 (1), 016030 (2021).
Mapping gauged Q-balls

Julian Heeck, Arvind Rajaraman, Rebecca Riley, and Christopher B. Verhaaren

Phys. Rev. D 103 (11), 116004 (2021).
Understanding Q-balls beyond the thin-wall limit

Julian Heeck, Arvind Rajaraman, Rebecca Riley, and Christopher B. Verhaaren

Phys. Rev. D 103 (4), 045008 (2021).

2020

Spurious poles in the scattering of electric and magnetic charges

John Terning and Christopher B. Verhaaren

J. High Energy Phys. 2020 (12), 153 (2020).
Dynamical evidence for a fifth force explanation of the ATOMKI nuclear anomalies

Jonathan L. Feng, Tim M. P. Tait, and Christopher B. Verhaaren

Phys. Rev. D 102 (3), 036016 (2020).
Breaking mirror twin color

Brian Batell, Wei Hu, and Christopher B. Verhaaren

J. High Energy Phys. 2020 (8), 9 (2020).
A minimal model for neutral naturalness and pseudo-Nambu-Goldstone dark matter

Aqeel Ahmed, Saereh Najjari, and Christopher B. Verhaaren

J. High Energy Phys. 2020 (6), 7 (2020).

2019

Detecting dark matter with Aharonov-Bohm

John Terning and Christopher B. Verhaaren

J. High Energy Phys. 2019 (12), 152 (2019).
Breaking mirror twin hypercharge

Brian Batell and Christopher B. Verhaaren

J. High Energy Phys. 2019 (12), 10 (2019).
Light hidden mesons through the Z portal

Hsin-Chia Cheng, Lingfeng Li, Ennio Salvioni, and Christopher B. Verhaaren

J. High Energy Phys. 2019 (11), 31 (2019).
Collider signals of the Mirror Twin Higgs boson through the hypercharge portal

Zackaria Chacko, Can Kilic, Saereh Najjari, and Christopher B. Verhaaren

Phys. Rev. D 100 (3), 035037 (2019).
HE-LHC: The High-Energy Large Hadron Collider

A. Abada, M. Abbrescia, S. S. AbdusSalam, I. Abdyukhanov, J. Abelleira Fernandez, A. Abramov, … C. B. Verhaaren, … (1,356 other authors)

Eur. Phys. J. Spec. Top. 228 (5), 1109-1382 (2019).
FCC-hh: The Hadron Collider

A. Abada, M. Abbrescia, S. S. AbdusSalam, I. Abdyukhanov, J. Abelleira Fernandez, A. Abramov, … C. B. Verhaaren, … (1,356 other authors)

Eur. Phys. J. Spec. Top. 228 (4), 755-1107 (2019).
FCC Physics Opportunities

A. Abada, M. Abbrescia, S. S. AbdusSalam, I. Abdyukhanov, J. Abelleira Fernandez, A. Abramov, … C. B. Verhaaren, … (1,356 other authors)

Eur. Phys. J. Spec. Top. 79 (6), 474 (2019).
FCC-ee: The Lepton Collider

A. Abada, M. Abbrescia, S. S. AbdusSalam, I. Abdyukhanov, J. Abelleira Fernandez, A. Abramov, … C. B. Verhaaren, … (1,355 other authors)

Eur. Phys. J. Spec. Top. 228 (2), 261-623 (2019).
Composite twin dark matter

John Terning, Christopher B. Verhaaren, and Kyle Zora

Phys. Rev. D 99 (9), 095020 (2019).
Discovering the twin Higgs boson with displaced decays

Can Kilic, Saereh Najjari, and Christopher B. Verhaaren

Phys. Rev. D 99 (7), 075029 (2019).
Singleton portals to the twin sector

Fady Bishara and Christopher B. Verhaaren

J. High Energy Phys. 2019 (5), 16 (2019).
Resolving the Weinberg paradox with topology

John Terning and Christopher B. Verhaaren

J. High Energy Phys. 2019 (3), 177 (2019).

2018

The CLIC potential for new physics

S. Alipour-Fard, W. Altmannshofer, A. Azatov, D. Azevedo, J. Baglio, M. Bauer, … C. B. Verhaaren, … (87 other authors)

CERN Yellow Reports: Monographs 3 (2018).
Dark monopoles and SL(2, ℤ) duality

John Terning and Christopher B. Verhaaren

J. High Energy Phys. 2018 (12), 123 (2018).
Singlet scalar top partners from accidental supersymmetry

Hsin-Chia Cheng, Lingfeng Li, Ennio Salvioni, and Christopher B. Verhaaren

J. High Energy Phys. 2018 (5), 57 (2018).
Testing the scalar sector of the twin Higgs model at colliders

Zackaria Chacko, Can Kilic, Saereh Najjari, and Christopher B. Verhaaren

Phys. Rev. D 97 (5), 055031 (2018).

2017

Beyond the Standard Model Phenomena

T. Golling, M. Hance, P. Harris, M.L. Mangano, M. McCullough, F. Moortgat, … C. Verhaaren, … (107 other authors)

CERN Yellow Reports: Monographs 3 (2017).

2016

A quirky probe of neutral naturalness

Zackaria Chacko, David Curtin, and Christopher B. Verhaaren

Phys. Rev. D 94 (1), 011504 (2016).
Quirky explanations for the diphoton excess

David Curtin and Christopher B. Verhaaren

Phys. Rev. D 93 (5), 055011 (2016).

2015

Discovering uncolored naturalness in exotic Higgs decays

David Curtin and Christopher B. Verhaaren

J. High Energy Phys. 2015 (12), 1-36 (2015).
Putting a stop to di-Higgs modifications

Brian Batell, Matthew McCullough, Daniel Stolarski, and Christopher B. Verhaaren

J. High Energy Phys. 2015 (9), 216 (2015).
Interactions of a stabilized radion and duality

Zackaria Chacko, Rashmish K. Mishra, Daniel Stolarski, and Christopher B. Verhaaren

Phys. Rev. D 92 (5), 056004 (2015).
A couplet from flavored dark matter

Prateek Agrawal, Zackaria Chacko, Can Kilic, and Christopher B. Verhaaren

J. High Energy Phys. 2015 (8), 72 (2015).
Colorless top partners, a 125 GeV Higgs boson, and the limits on naturalness

Gustavo Burdman, Zackaria Chacko, Roni Harnik, Leonardo de Lima, and Christopher B. Verhaaren

Phys. Rev. D 91 (5), 055007 (2015).

2014

Leptophilic dark matter and the anomalous magnetic moment of the muon

Prateek Agrawal, Zackaria Chacko, and Christopher B. Verhaaren

J. High Energy Phys. 2014 (8), 147 (2014).

2012

Unifying the inertia and Riemann curvature tensors through geometric algebra

M. Berrondo, J. Greenwald^‡, and C. Verhaaren^†

Am. J. Phys. 80 (10), 905-912 (2012).

2010

Dispersive dielectrics and time reversal: Free energies, orthogonal spectra, and parity in dissipative media

Scott Alan Glasgow, John Corson^†, and Chris Verhaaren^†

Phys. Rev. E 82 (1), 011115 (2010).
Chaotic orbits for spinning particles in Schwarzschild spacetime

Chris Verhaaren^† and Eric W. Hirschmann

Phys. Rev. D 81 (12), 124034 (2010).

^‡Undergraduate Student Author

^†Graduate Student Author

Selected Publications

Benjamin DeVries and Christopher B. Verhaaren (et al.)

Non-topological solitons, such as Q-balls, may contribute to the cosmological dark matter. The formation and evolution of Q-balls in the early universe requires an understanding of solitons with nonzero angular momentum. We derive (rather than assume) the schematic form of the scalar field configurations that produce rotating Q-balls, which produce their well known quantized angular momentum. This analysis leads to additional insight into the properties of these rotating solitons, including a method for computing their characteristic angular velocity. By considering rotating solitons in two spatial dimensions, we investigate these attributes concretely. We develop analytical approximations for the solitons and their defining quantities. We show that they agree with numerical results and exhibit the general properties of rotating solitons.

Christopher B. Verhaaren (et al.)

The hierarchy between the mass parameter of the Higgs boson and larger mass scales becomes ever more puzzling as experiments explore higher energies. Neutral naturalness is the umbrella term for symmetry-based explanations for these hierarchies whose quark symmetry partners are not charged under the SU(3)

color gauge group of the Standard Model. Though the first manifestations of this idea predate the physics runs of the Large Hadron Collider, since the Higgs discovery this paradigm has grown and developed to include a wide variety of concrete realizations with connections to intriguing collider signals. Determining the phenomenology of such models often requires the characterization—typically relying on lattice calculations—of a new confining gauge symmetry. This presents additional motivation to further develop our understanding of nonperturbative field theory as well as to pursue specific lattice studies. The wide range of suggested hidden sectors also produces a variety of dark matter candidates, intersections with astrophysics and cosmology, and ties to neutrinos and flavor. In this review, we orient the reader within both this growing collection of specific models and the physical phenomena they produce. We also survey the often less familiar dynamics of hidden-sector glueballs and quirks. In addition to providing a guide to past efforts, we reveal interesting directions for further study.

C. B. Verhaaren (et al.)

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. The content and structure of this report are guided by the scope and priorities defined in the mandate of the FCC Feasibility Study. It is therefore not intended to serve as an exhaustive review of the full physics potential of FCC. Several topics, already covered in earlier reports such as the FCC CDR, are not reiterated here or are addressed only briefly, in alignment with the study’s focus. 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.

C. B. Verhaaren (et al.)

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. The FCC-ee is designed to operate at four key centre-of-mass energies: the Z pole, the WW pair production threshold, the ZH production peak, and the top/anti-top production threshold—each 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 between the Z, WW, and ZH substages remains flexible. The 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 upcoming High-Luminosity LHC. Its mass reach for direct discovery extends to several tens of TeV. In addition to proton-proton collisions, the 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.

Thomas Cochran, Logan Page, and Christopher B. Verhaaren (et al.)

We describe a novel variation of the mirror twin Higgs model in which the color gauge group in both sectors is extended to SU(4)c and spontaneously broken to SU(3)c exclusively in the visible sector. Through this process, the mirror Z2 symmetry is spontaneously broken, allowing for a phenomenologically viable electroweak vacuum alignment. This structure produces interesting collider signatures, including heavy vectors and fermions with fractional electric charges. The twin sector, with unbroken SU(4)c, produces interesting cosmological characteristics, such as the possibility to reduce ∆Neff and stable spin-0 baryons. The enlarged top quark sector required by the extended color gauge symmetry preserves naturalness, with even less tuning than the original twin Higgs in many circumstances.

C. B. Verhaaren (et al.)

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 the 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 summary of the studies conducted to document the current state of the environment.