#---------------------------------------------------------------------# Alberto Mariotti Vrije Universiteit Brussel (VUB) https://hep.research.vub.be Phone: +32 (0) 2 629 32 15 E-mail: alberto.mariotti@vub.be Address: Vrije Universiteit Brussel Physics Department Pleinlaan 2, 1050 Brussels, Belgium #---------------------------------------------------------------------#

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From: FACCHINETTI Gaëtan gaetan.facchinetti@ulb.be Subject: Re: ULB PhysTH Seminar by Jeesun Sk - 23/09/2024 at 11 am Date: 17 September 2024 at 08:29:05 CEST To: GRP_ULB_PhysTh GRP_phys_th@ulb.be, GRP_ULB_Sem_Add GRP_physth_sem@ulb.be Resent-From: alberto.mariotti@vub.be

Dear All,

Please find below the title and abstract for next-week seminar (Monday 23/09/2024 at 11 am).

Studying dark sector imprints in cosmology and ground based experiments Relativistic degrees of freedom or N_eff is one of the crucial cosmological parameters and is sensitive to extra radiation energy density at the time of neutrino decoupling. The precise measurement of $N_eff$ at the time of CMB formation by Planck 2018 can be used to understand fundamental interactions and to shed light on beyond standard model (BSM) scenarios. In this talk I will explain how N_eff can probe light (MeV) freeze in dark matter models which contain additional neutrino injection at late time. We propose a scenario where a long lived scalar decays to a dark matter and active neutrinos after BBN. Despite the feeble coupling of DM the parameter space can be probed via N_eff. I will also talk about how N_eff at CMB can constrain light Z' gauge boson realized in generic BSM U(1)_X scenarios. Finally, from the perspective of ground based experiments, I will show how table top experiments like optically trapped nanospheres can shed light on MeV scale dark matter and other BSM particles like ALP.

Best regards,

Gaétan

...

Le 16 sept. 2024 à 13:23, FACCHINETTI Gaëtan gaetan.facchinetti@ulb.be a écrit :

Dear All,

I am happy to announce our first seminar of this academic year. Jesus Sk (IACS, Kolkata) will give us a seminar next Monday, the 23rd of September, at 11am in room 2.N7.110 (building NO, campus Plaine). Please note the unusual time slot! In case 11am is inconvenient for too many of you, please let me know and we can try to move it later that day (if it suits the speaker too). The title and abstract will be sent as soon as possible.

Best regards,

Gaétan

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