Zackaria Chacko
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View article: Searching for hidden sector particles at neutrino telescopes
Searching for hidden sector particles at neutrino telescopes Open
We explore the possibility of directly detecting light, long-lived hidden sector particles at the IceCube neutrino telescope. Such particles frequently arise in nonminimal hidden sectors that couple to the Standard Model through portal ope…
View article: Atomic dark matter, interacting dark radiation, and the Hubble tension
Atomic dark matter, interacting dark radiation, and the Hubble tension Open
A bstract We present a new class of interacting dark sector models that can address the Hubble tension. Interacting dark radiation (DR) has previously been put forward as a solution to the problem, but this proposal is disfavored by the hi…
View article: Searching for Hidden Sector Particles at Neutrino Telescopes
Searching for Hidden Sector Particles at Neutrino Telescopes Open
We explore the possibility of directly detecting light, long-lived hidden sector particles at the IceCube neutrino telescope. Such particles frequently arise in non-minimal hidden sectors that couple to the Standard Model through portal op…
View article: General form of effective operators from hidden sectors
General form of effective operators from hidden sectors Open
A bstract We perform a model-independent analysis of the dimension-six terms that are generated in the low energy effective theory when a hidden sector that communicates with the Standard Model (SM) through a specific portal operator is in…
View article: General form of effective operators from hidden sectors
General form of effective operators from hidden sectors Open
We perform a model-independent analysis of the dimension-six terms that are generated in the low energy effective theory when a hidden sector that communicates with the Standard Model (SM) through a specific portal operator is integrated o…
View article: Atomic Dark Matter, Interacting Dark Radiation, and the Hubble Tension
Atomic Dark Matter, Interacting Dark Radiation, and the Hubble Tension Open
We present a new class of interacting dark sector models that can address the Hubble tension. Interacting dark radiation (DR) has previously been put forward as a solution to the problem, but this proposal is disfavored by the high-$\ell$ …
View article: Composite dark matter and neutrino masses from a light hidden sector
Composite dark matter and neutrino masses from a light hidden sector Open
A bstract We study a class of models in which the particle that constitutes dark matter arises as a composite state of a strongly coupled hidden sector. The hidden sector interacts with the Standard Model through the neutrino portal, allow…
View article: Stepped partially acoustic dark matter: likelihood analysis and cosmological tensions
Stepped partially acoustic dark matter: likelihood analysis and cosmological tensions Open
We generalize the recently proposed Stepped Partially Acoustic Dark Matter (SPartAcous) model by including additional massless degrees of freedom in the dark radiation sector. We fit SPartAcous and its generalization against cosmological p…
View article: Neutrino masses from low scale partial compositeness
Neutrino masses from low scale partial compositeness Open
We consider a class of models in which the neutrinos acquire Majorana masses through mixing with singlet neutrinos that emerge as composite states of a strongly coupled hidden sector. In this framework, the light neutrinos are partially co…
View article: Stepped Partially Acoustic Dark Matter: Likelihood Analysis and Cosmological Tensions
Stepped Partially Acoustic Dark Matter: Likelihood Analysis and Cosmological Tensions Open
We generalize the recently proposed Stepped Partially Acoustic Dark Matter (SPartAcous) model by including additional massless degrees of freedom in the dark radiation sector. We fit SPartAcous and its generalization against cosmological p…
View article: Stepped partially acoustic dark matter, large scale structure, and the Hubble tension
Stepped partially acoustic dark matter, large scale structure, and the Hubble tension Open
A bstract We propose a new interacting dark sector model, Stepped Partially Acoustic Dark Matter (SPartAcous), that can simultaneously address the two most important tensions in current cosmological data, the H 0 and S 8 problems. As in th…
View article: Composite Dark Matter and Neutrino Masses from a Light Hidden Sector
Composite Dark Matter and Neutrino Masses from a Light Hidden Sector Open
We study a class of models in which the particle that constitutes dark matter arises as a composite state of a strongly coupled hidden sector. The hidden sector interacts with the Standard Model through the neutrino portal, allowing the re…
View article: Improved cosmological constraints on the neutrino mass and lifetime
Improved cosmological constraints on the neutrino mass and lifetime Open
We present cosmological constraints on the sum of neutrino masses as a function of the neutrino lifetime, in a framework in which neutrinos decay into dark radiation after becoming non-relativistic. We find that in this regime the cosmic m…
View article: Searching for a fifth force with atomic and nuclear clocks
Searching for a fifth force with atomic and nuclear clocks Open
We consider the general class of theories in which there is a new ultralight scalar field that mediates an equivalence principle violating, long-range force. In such a framework, the Sun and Earth act as sources of the scalar field, leadin…
View article: Stepped Partially Acoustic Dark Matter, Large Scale Structure, and the Hubble Tension
Stepped Partially Acoustic Dark Matter, Large Scale Structure, and the Hubble Tension Open
We propose a new interacting dark sector model, Stepped Partially Acoustic Dark Matter (SPartAcous), that can simultaneously address the two most important tensions in current cosmological data, the $H_0$ and $S_8$ problems. As in the Part…
View article: Searching for a Fifth Force with Atomic and Nuclear Clocks
Searching for a Fifth Force with Atomic and Nuclear Clocks Open
We consider the general class of theories in which there is a new ultralight scalar field that mediates an equivalence principle violating, long-range force. In such a framework, the sun and the earth act as sources of the scalar field, le…
View article: Cosmological signatures of a mirror twin Higgs
Cosmological signatures of a mirror twin Higgs Open
Here, we explore the cosmological signatures associated with the twin baryons, electrons, photons and neutrinos in the Mirror Twin Higgs framework. We consider a scenario in which the twin baryons constitute a subcomponent of dark matter, …
View article: Leptophilic dark matter and the anomalous magnetic moment of the muon
Leptophilic dark matter and the anomalous magnetic moment of the muon Open
We consider renormalizable theories such that the scattering of dark matter off leptons arises at tree level, but scattering off nuclei only arises at loop. In this framework, the various dark matter candidates can be classified by their s…
View article: The International Linear Collider: Report to Snowmass 2021
The International Linear Collider: Report to Snowmass 2021 Open
The International Linear Collider (ILC) is on the table now as a new global energy-frontier accelerator laboratory taking data in the 2030s. The ILC addresses key questions for our current understanding of particle physics. It is based on …
View article: The International Linear Collider: Report to Snowmass 2021
The International Linear Collider: Report to Snowmass 2021 Open
The International Linear Collider (ILC) is on the table now as a new global energy-frontier accelerator laboratory taking data in the 2030s. The ILC addresses key questions for our current understanding of particle physics. It is based on …
View article: Time-varying fine structure constant from naturally ultralight dark matter
Time-varying fine structure constant from naturally ultralight dark matter Open
We present a class of models in which the coupling of the photon to an ultralight scalar field that has a time-dependent vacuum expectation value causes the fine structure constant to oscillate in time. The scalar field is assumed to const…
View article: Determining the neutrino lifetime from cosmology
Determining the neutrino lifetime from cosmology Open
We explore the cosmological signals of theories in which the neutrinos decay\ninto invisible dark radiation after becoming non-relativistic. We show that in\nthis scenario, near-future large scale structure measurements from the Euclid\nsa…
View article: Determining the Neutrino Lifetime from Cosmology
Determining the Neutrino Lifetime from Cosmology Open
We explore the cosmological signals of theories in which the neutrinos decay into invisible dark radiation after becoming non-relativistic. We show that in this scenario, near-future large scale structure measurements from the Euclid satel…
View article: Collider signals of the Mirror Twin Higgs boson through the hypercharge portal
Collider signals of the Mirror Twin Higgs boson through the hypercharge portal Open
We consider the collider signals arising from kinetic mixing between the hypercharge gauge boson of the Standard Model and its twin counterpart in the Mirror Twin Higgs model, in the framework in which the twin photon is massive. Through t…
View article: Detecting a secondary cosmic neutrino background from Majoron decays in neutrino capture experiments
Detecting a secondary cosmic neutrino background from Majoron decays in neutrino capture experiments Open
We consider theories in which the generation of neutrino masses is associated\nwith the breaking of an approximate global lepton number symmetry. In such a\nscenario the spectrum of light states includes the Majoron, the pseudo-Nambu\nGold…
View article: The CLIC Potential for New Physics
The CLIC Potential for New Physics Open
The Compact Linear Collider (CLIC) is a mature option for the future of high energy physics. It combines the benefits of the clean environment of $e^+e^-$ colliders with operation at high centre-of-mass energies, allowing to probe scales b…