We demonstrate that cosmological observations place strong bounds on the reheat temperature $\textit{T}$ of the Standard Model (SM) in minimal models of ‘quirks’ — heavy fermions transforming under the SM gauge group together with a new non-Abelian gauge interaction with a confinement scale far below the mass of the fermions. These models have unique collider signals associated with the confining flux strings, which cannot break due to the large mass of the quirks. Our work shows that in these models $\textit{T}$ ≲ 𝒪(100) GeV for the entire ‘quirky’ parameter space where the effects of the flux string are important. These bounds are in tension with most models of baryogenesis, showing that the discovery of quirks at colliders can have far-reaching implications for cosmology. The bounds arise because the irreducible relic abundance of glueballs from UV freeze-in, combined with their long lifetimes, leads to constraints from the disruption of BBN, distortions of the CMB, excess $\textit{γ}$-rays, an over-abundance of self-interacting dark matter, and contributions to ∆$\textit{N}$ . The glueball freeze-in abundance has a strong dependence on $\textit{T}$ , making the bounds relatively insensitive to strong interaction uncertainties. The bounds are robust to the SM quantum numbers of the quirks and the presence of Yukawa couplings with the Higgs. In non-minimal extensions of the model where the glueballs can decay to an additional dark sector, the bounds remain for models where the flux string has a macroscopic length at colliders. We also show that for quirk masses above ~ 10 TeV, the dark glueballs can be the dominant component of dark matter. This work illustrates a striking connection between quirky collider signals and cosmological probes of new physics, strengthening the case for targeted quirk searches at colliders.

United States

Pouya Asadi

Switzerland

Graham Kribs

Markus Luty

Quirks live in cool universes

Dark sectors with confining gauge interactions can provide both simple dark matter candidates and striking signals at colliders. We recast Large Hadron Collider searches for two different signatures of dark mesons that arise from a strongly-coupled theory with vector-like dark quarks that are in some non-trivial representation of Standard Model SU(2) . For any such electroweak representation, there is a 3-plet of dark mesons whose charged components are long-lived, and we reinterpret searches for disappearing tracks to place a lower bound on their mass of ~ 1.2 TeV. When the dark quarks are in SU(2) representations larger than the fundamental, there is also a 5-plet of dark mesons that interacts with the electroweak gauge bosons via a chiral anomaly. We show that the 5-plet is the unique non-trivial meson multiplet with this anomaly and recast searches for the resulting diboson resonances to place bounds on model parameters. With additional measurements, the anomaly also enables one to reconstruct some ultraviolet parameters (the numbers of dark flavors and colors) while only measuring states in the infrared. Each of these signals represents an exciting opportunity for future searches using higher luminosity.

Austin Batz

Elias Bernreuther

Canada

Marco Costa

Samuel Homiller

Stopping dark mesons in their tracks with long-lived particle and resonant signatures

In the framework of AdS/CFT correspondence, the Fefferman-Graham (FG) gauge offers a useful way to express asymptotically anti-de Sitter spaces, allowing a clear identification of their boundary structure. A known feature of this approach is that choosing a particular conformal representative for the boundary metric breaks explicitly the boundary scaling symmetry. Recent developments have shown that it is possible to generalize the FG gauge to restore boundary Weyl invariance by adopting the Weyl-Fefferman-Graham gauge. In this paper, we focus on three-dimensional gravity and study the emergence of a boundary Weyl structure when considering the most general AdS boundary conditions introduced by Grumiller and Riegler [1]. We extend the holographic renormalization scheme to incorporate Weyl covariant quantities, identifying new subleading divergences appearing at the boundary. To address these, we introduce a new codimension-two counterterm, or corner term, that ensures the finiteness of the gravitational action. From here, we construct the quantum-generating functional, the holographic stress tensor, and compute the corresponding Weyl anomaly, showing that the latter is now expressed in a full Weyl covariant way. Finally, we discuss explicit applications to holographic integrable models and accelerating black holes. For the latter, we show that the new corner term plays a crucial role in the computation of the Euclidean on-shell action.

China

Gabriel Arenas-Henriquez

Russia

Felipe Diaz

David Rivera-Betancour

Generalized Fefferman-Graham gauge and boundary Weyl structures

Inelastic dark matter with moderate splittings,   <math> <mi>O</mi> </math>  $$ \mathcal{O} $$ (few to 150) keV, can upscatter to an excited state in the Earth, with the excited state subsequently decaying, leaving a distinctive monoenergetic photon signal in large underground detectors. The photon signal can exhibit sidereal-daily modulation, providing excellent separation from backgrounds. Using a detailed numerical simulation, we examine this process as a search strategy for magnetic inelastic dark matter with the dark matter mass near the weak scale, where the upscatter to the excited state and decay proceed through the same magnetic dipole transition operator. At lower inelastic splittings, the scattering is dominated by moderate mass elements in the Earth with high spin, especially 27Al, while at larger splittings, 56Fe becomes the dominant target. We show that the proposed large volume gaseous detector CYGNUS will have excellent sensitivity to this signal. Xenon detectors also provide excellent sensitivity through the inelastic nuclear recoil signal, and if a future signal is seen, we show that the synergy among both types of detection can provide strong evidence for magnetic inelastic dark matter. In the course we have calculated nuclear response functions for elements relevant for scattering in the Earth, which are publicly available on  GitHub  .

Japan

Sweden

Joshua Eby

Patrick Fox

Earth-catalyzed detection of magnetic inelastic dark matter with photons in large underground detectors

We study confining dark sectors where the lightest hadrons are glueballs. Such models can provide viable dark matter candidates and appear in some neutral naturalness scenarios. In this work, we introduce a new phenomenological model of dark glueball hadronization inspired by the Lund string model. This enables us to make the most physically-motivated predictions for dark glueball phenomenology at the LHC to date. Our model approximately reproduces the expected thermal distribution of hadron species as an emergent consequence of hadronization dynamics. The ability to predict the production of glueball states heavier than the lightest species significantly expands the reach of long-lived glueball searches in MATHUSLA compared to previous simplified estimates. We also characterize regions of parameter space where emerging and/or semivisible jets could arise from pure-glue dark sectors, thereby providing new benchmark models that motivate searches for these signatures.

CERN

Timothy Cohen

David Curtin

Caleb Gemmell

Dark sector glueballs at the LHC

We investigate the asymptotic symmetries of three-dimensional AdS Einstein gravity in the Weyl-Fefferman-Graham gauge, which is a generalization of the Fefferman-Graham gauge inducing a Weyl connection as part of the boundary structure. We show that this gauge arises as a natural intermediary step of the gauge-fixing procedure in the Chern–Simons formulation. We prove that the diffeomorphism required to go to the usual Fefferman–Graham gauge can be charged, and thus its implementation has physical repercussions. We discuss the holographic renormalization and the variational principle offering a new holographic take on this gauge and its charges.

Luca Ciambelli

Belgium

Arnaud Delfante

United Kingdom

Austria

Romain Ruzziconi

Céline Zwikel

Symmetries and charges in Weyl-Fefferman-Graham gauge

Massive U(1) gauge theories featuring parametrically light vectors are suspected to belong in the Swampland of consistent EFTs that cannot be embedded into a theory of quantum gravity. We study four-dimensional, chiral U(1) gauge theories that appear anomalous over a range of energies up to the scale of anomaly-cancelling massive chiral fermions. We show that such theories must be UV-completed at a finite cutoff below which a radial mode must appear, and cannot be decoupled — a Stückelberg limit does not exist. When the infrared fermion spectrum contains a mixed U(1)-gravitational anomaly, this class of theories provides a toy model of a boundary into the Swampland, for sufficiently small values of the vector mass. In this context, we show that the limit of a parametrically light vector comes at the cost of a quantum gravity scale that lies parametrically below M P1, and our result provides field theoretic evidence for the existence of a Swampland of EFTs that is disconnected from the subset of theories compatible with a gravitational UV-completion. Moreover, when the low energy theory also contains a U(1)3 anomaly, the Weak Gravity Conjecture scale makes an appearance in the form of a quantum gravity cutoff for values of the gauge coupling above a certain critical size.

Nathaniel Craig

Isabel Garcia

The UV fate of anomalous U(1)s and the Swampland

We study luminous dark matter signals in models with inelastic scattering. Dark matter χ 1 that scatters inelastically off elements in the Earth is kicked into an excited state χ 2 that can subsequently decay into a monoenergetic photon inside a detector. The photon signal exhibits large sidereal-daily modulation due to the daily rotation of the Earth and anisotropies in the problem: the dark matter wind comes from the direction of Cygnus due to the Sun's motion relative to the galaxy, and the rock overburden is anisotropic, as is the dark matter scattering angle. This allows outstanding separation of signal from backgrounds. We investigate the sensitivity of two classes of large underground detectors to this modulating photon line signal: large liquid scintillator neutrino experiments, including Borexino and JUNO, and the proposed large gaseous scintillator directional detection experiment CYGNUS. Borexino's (JUNO's) sensitivity exceeds the bounds from xenon experiments on inelastic nuclear recoil for mass splittings   <math> <mi>δ</mi> <munder> <mo>&gt;</mo> <mo>˜</mo> </munder> </math>  $$ \delta \underset{\sim }{&gt;} $$  240 (180) keV, and is the only probe of inelastic dark matter for 350 keV   <math> <munder> <mo>&lt;</mo> <mo>˜</mo> </munder> <mi>δ</mi> <munder> <mo>&lt;</mo> <mo>˜</mo> </munder> </math>  $$ \underset{\sim }{&lt;}\delta \underset{\sim }{&lt;} $$  600 keV. CYGNUS's sensitivity is at least comparable to xenon experiments with ~ 10m3 volume detector for   <math> <mi>δ</mi> <munder> <mo>&lt;</mo> <mo>˜</mo> </munder> </math>  $$ \delta \underset{\sim }{&lt;} $$  150 keV, and could be substantially better with larger volumes and improved background rejection. Such improvements lead to the unusual situation that the inelastic signal becomes the superior way to search for dark matter even if the elastic and inelastic scattering cross sections are comparable.

Israel

Roni Harnik

Luminous signals of inelastic dark matter in large detectors

A new, strongly-coupled “dark” sector could be accessible to LHC searches now. These dark sectors consist of composites formed from constituents that are charged under the electroweak group and interact with the Higgs, but are neutral under Standard Model color. In these scenarios, the most promising target is the dark meson sector, consisting of dark vector-mesons as well as dark pions. In this paper we study dark meson production and decay at the LHC in theories that preserve a global SU(2) dark flavor symmetry. Dark pions — like the pions of QCD — can be pair-produced through resonant dark vector meson production, pp → ρ  D  → π  D  π  D , and decay in one of two distinct ways: “gaugephobic”, when   <math> <msub> <mi>π</mi> <mi>D</mi> </msub> <mo>→</mo> <mi>f</mi> <msup> <mover> <mi>f</mi> <mo>¯</mo> </mover> <mo>′</mo> </msup> </math>  $$ {\pi}_D\to f{\overline{f}}^{\prime } $$  generally dominates; or “gaugephilic”, when π  D  → W + h, Z + h dominates once kinematically open. Unlike QCD, the decay π   D  0  → γγ is virtually absent due to the dark flavor symmetry. We recast a vast set of existing LHC searches to determine the current constraints on (and future opportunities for) dark meson production and decay. When   <math> <msub> <mi>m</mi> <msub> <mi>ρ</mi> <mi>D</mi> </msub> </msub> </math>  $$ {m}_{\rho_D} $$  is slightly heavier than   <math> <mn>2</mn> <msub> <mi>m</mi> <msub> <mi>π</mi> <mi>D</mi> </msub> </msub> </math>  $$ 2{m}_{\pi_D} $$  and ρ   D  ±,0  kinetically mixes with the weak gauge bosons, the 8 TeV same-sign lepton search strategy sets the best bound,   <math> <msub> <mi>m</mi> <msub> <mi>π</mi> <mi>D</mi> </msub> </msub> </math>  $$ {m}_{\pi_D} $$  &gt; 500 GeV. Yet, when only the ρ   D  0  kinetically mixes with hypercharge, we find the strongest LHC bound is   <math> <msub> <mi>m</mi> <msub> <mi>π</mi> <mi>D</mi> </msub> </msub> </math>  $$ {m}_{\pi_D} $$  &gt; 130 GeV, that is only slightly better than what LEP II achieved two decades ago. We find the relative insensitivity of LHC searches, especially at 13 TeV, can be blamed mainly on their penchant for high mass objects or large missing energy. Dedicated searches would undoubtedly yield substantially improved sensitivity. We provide a GitHub page to speed the implementation of these searches in future LHC analyses. Our findings for dark meson production and decay provide a strong motivation for model-independent searches of the form pp → A → B + C → SM SM + SM SM where the theoretical prejudice is for SM to be a 3rd generation quark or lepton, W, Z, or h.

Adam Martin

Bryan Ostdiek

Tom Tong

Dark mesons at the LHC

Dark mesons are bosonic composites of a new, strongly-coupled sector beyond the Standard Model. We consider several dark sectors with fermions that transform under the electroweak group, as arise from a variety of models including strongly-coupled theories of dark matter (e.g., stealth dark matter), bosonic technicolor (strongly-coupled indcued electroweak symmetry breaking), vector-like confinement, etc. We consider theories with two and four flavors under an SU(N) strong group that acquire variously chiral, vector-like, and mixed contributions to their masses. We construct the non-linear sigma model describing the dark pions and match the ultraviolet theory onto a low energy effective theory that provides the leading interactions of the lightest dark pions with the Standard Model. We uncover two distinct classes of effective theories that are distinguishable by how the lightest dark pions decay: “Gaugephilic”: where π0 → Zh, π± → W h dominate once kinematically open, and “Gaugephobic”: where   <math> <msup> <mi>π</mi> <mn>0</mn> </msup> <mo>→</mo> <mover> <mi>f</mi> <mo>¯</mo> </mover> <mi>f</mi> </math>  $$ {\pi}^0\to \overline{f}f $$ ,   <math> <msup> <mi>π</mi> <mo>±</mo> </msup> <mo>→</mo> <mover> <mi>f</mi> <mo>¯</mo> </mover> <mo>′</mo> <mi>f</mi> </math>  $$ {\pi}^{\pm}\to \overline{f}^{\prime }f $$  dominate. Custodial SU(2) plays a critical role in determining the “philic” or “phobic” nature of a model. In dark sectors that preserve custodial SU(2), there is no axial anomaly, and so the decay π 0 → γγ is highly suppressed. In a companion paper, we study dark pion production and decay at colliders, obtaining the constraints and sensitsivity at the LHC.

Effective theories of dark mesons with custodial symmetry