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We study the discovery prospects of leptophilic dark matter (DM) in future lepton colliders by considering the light neutrinos to be of Dirac type. Adopting an effective field theory (EFT) approach, we write down dimension six operators…

High Energy Physics - Phenomenology · Physics 2025-11-14 Debasish Borah , Nayan Das , Sahabub Jahedi , Bhavya Thacker

It is usually assumed that relic neutrinos possess a Fermi-Dirac distribution, acquired during thermal equilibrium in the Early Universe. However, various mechanisms could introduce strong distortions in this distribution. We perform a…

Astrophysics · Physics 2010-12-09 A. Cuoco , J. Lesgourgues , G. Mangano , S. Pastor

Cosmological observations are becoming increasingly sensitive to the effects of light particles in the form of dark radiation (DR) at the time of recombination. The conventional observable of effective neutrino number, $N_{\rm eff}$, is…

Cosmology and Nongalactic Astrophysics · Physics 2017-08-30 Christopher Brust , Yanou Cui , Kris Sigurdson

Of the many proposed extensions to the $\Lambda$CDM paradigm, a model in which neutrinos self-interact until close to the epoch of matter-radiation equality has been shown to provide a good fit to current cosmic microwave background (CMB)…

Cosmology and Nongalactic Astrophysics · Physics 2019-09-25 Minsu Park , Christina D. Kreisch , Jo Dunkley , Boryana Hadzhiyska , Francis-Yan Cyr-Racine

In the early universe, Dirac neutrino magnetic moments due to their chirality-flipping nature could lead to thermal production of right-handed neutrinos, which would make a significant contribution to the effective neutrino number, $N_{\rm…

High Energy Physics - Phenomenology · Physics 2023-04-04 Shao-Ping Li , Xun-Jie Xu

Perturbations in the cosmic neutrino background produce a characteristic phase shift in the acoustic oscillations imprinted in the anisotropies of the cosmic microwave background (CMB), providing a unique observational probe of neutrino…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-18 Gabriele Montefalcone , Subhajit Ghosh , Kimberly K. Boddy , Daven Wei Ren Ho , Yuhsin Tsai

We consider Big Bang nucleosynthesis and the cosmic microwave background when both the neutrino temperature and neutrino number are allowed to vary from their standard values. The neutrino temperature is assumed to differ from its standard…

Cosmology and Nongalactic Astrophysics · Physics 2017-03-15 Richard Galvez , Robert J. Scherrer

The gauge-singlet right-handed neutrinos would be essential to explain the tiny masses of active neutrinos. We consider the effective field theory of the Standard Model extended with these fields under the assumption that neutrinos are…

High Energy Physics - Phenomenology · Physics 2025-09-19 Anirban Biswas , Eung Jin Chun , Sanjoy Mandal , Dibyendu Nanda

We explore the possibility of redshift-dependent deviations in the contribution of relativistic degrees of freedom to the radiation budget of the cosmos, conventionally parameterized by the effective number of neutrinos $N_{\rm eff}$, from…

Cosmology and Nongalactic Astrophysics · Physics 2024-12-17 Sarah Safi , Marzieh Farhang , Olga Mena , Eleonora Di Valentino

We perform a comprehensive study of cosmological constraints on non-standard neutrino self-interactions using cosmic microwave background (CMB) and baryon acoustic oscillation data. We consider different scenarios for neutrino…

Cosmology and Nongalactic Astrophysics · Physics 2021-09-22 Thejs Brinckmann , Jae Hyeok Chang , Marilena LoVerde

The connection between cosmological observations and neutrino physics is discussed in detail. Neutrinos decouple from thermal contact in the early Universe at a temperature of order 1 MeV which coincides with the temperature where light…

High Energy Physics - Phenomenology · Physics 2008-11-26 Steen Hannestad

We evaluate the ability of future cosmic microwave background (CMB) experiments to measure the power spectrum of large scale structure using quadratic estimators of the weak lensing deflection field. We calculate the sensitivity of upcoming…

Astrophysics · Physics 2009-11-13 Julien Lesgourgues , Laurence Perotto , Sergio Pastor , Michel Piat

We analyze signals in the Cosmic Microwave Background (CMB) in theories where the small Dirac neutrino masses arise as a consequence of the compositeness of right-handed neutrinos. In such theories, the right-handed neutrinos are massless…

High Energy Physics - Phenomenology · Physics 2011-07-19 Takemichi Okui

The relativistic degrees of freedom ($N_{\rm eff}$) is one of the crucial cosmological parameters. The precise measurement of $N_{\rm eff}$ at the time of cosmic microwave background formation, by Planck 2018 can be used to understand the…

High Energy Physics - Phenomenology · Physics 2024-09-24 Dilip Kumar Ghosh , Purusottam Ghosh , Sk Jeesun , Rahul Srivastava

In this paper, we put forward a connection between the self-interacting dark matter and the Dirac nature of neutrinos. Our exploration involves a $Z_4 \otimes Z_4'$ discrete symmetry, wherein the Dirac neutrino mass is produced through a…

High Energy Physics - Phenomenology · Physics 2024-03-05 Satyabrata Mahapatra , Sujit Kumar Sahoo , Narendra Sahu , Vicky Singh Thounaojam

Recent work on increasing the effective number of neutrino species (Neff) in the early universe has focussed on introducing extra relativistic species (`dark radiation'). We draw attention to another possibility: a new particle of mass less…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 Celine Boehm , Matthew J. Dolan , Christopher McCabe

New interactions of neutrinos can stop them from free streaming even after the weak interaction freeze-out. This results in a phase shift in the cosmic microwave background (CMB) acoustic peaks which can alleviate the Hubble tension. In…

High Energy Physics - Phenomenology · Physics 2021-01-12 Subhajit Ghosh , Rishi Khatri , Tuhin S. Roy

We study scatter-like interactions between neutrinos and dark matter in light of different combinations of temperature, polarization and lensing data released by three independent CMB experiments - the Planck satellite, the Atacama…

Cosmology and Nongalactic Astrophysics · Physics 2024-03-15 William Giarè , Adrià Gómez-Valent , Eleonora Di Valentino , Carsten van de Bruck

The self-interacting neutrino hypothesis is well motivated for addressing the tension between the origin of sterile neutrino dark matter and indirect detection constraints. It can also result in a number of testable signals from the…

High Energy Physics - Phenomenology · Physics 2022-06-01 Kevin J. Kelly , Manibrata Sen , Yue Zhang