BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//CERN//INDICO//EN
BEGIN:VEVENT
SUMMARY:Resolving cosmological tensions with a sign-switching cosmological
  constant
DTSTART;VALUE=DATE-TIME:20230601T101500Z
DTEND;VALUE=DATE-TIME:20230601T104000Z
DTSTAMP;VALUE=DATE-TIME:20260907T150952Z
UID:indico-contribution-979@cern.ch
DESCRIPTION:Speakers: Ozgur AKARSU ()\nIn this talk\, inspired by the rece
 nt conjecture originated from graduated dark energy (gDE) that the univers
 e has transitioned from anti-de Sitter vacua to de Sitter vacua in the lat
 e universe\, we will discuss the superior features of the $\\Lambda_{\\rm 
 s}$CDM model\, which extends the standard $\\Lambda$CDM model by a cosmolo
 gical constant ($\\Lambda_{\\rm s}$) that switches sign at a certain redsh
 ift $z_\\dagger$\, over the standard $\\Lambda$CDM model in the light of o
 bservational data. We will first discuss that\, when the consistency of $\
 \Lambda_{\\rm s}$CDM with the CMB data is ensured\, $H_0$ and $M_B$ values
  are inversely correlated with $z_\\dagger$ and reach $H_0\\approx73.4~{\\
 rm km\\\, s^{-1}\\\, Mpc^{-1}}$ and $M_B\\approx-19.25\\\,{\\rm mag}$ for 
 $z_\\dagger=1.6$\, in agreement with the SH0ES measurements\, and $H(z)$ e
 xhibits an excellent fit to the Ly-$\\alpha$ data. We will then show that 
 the CMB alone is not able to well constrain $z_\\dagger$ and thus discrimi
 nate between $\\Lambda_{\\rm s}$CDM and $\\Lambda$CDM models\, but the CMB
 +BAO data set favors the sign switch of $\\Lambda_{\\rm s}$ providing the 
 constraint: $z_\\dagger=2.44\\pm0.29$. The further observational analysis 
 using more data sets reveals that $\\Lambda_{\\rm s}$CDM is significantly 
 favored over $\\Lambda$CDM\, and it resolves various tensions that prevail
  within $\\Lambda$CDM\; for instance\, the CMB+Pan data set with $M_B$ pri
 or gives $z_\\dagger=1.784^{+0.14}_{-0.18}$ along with $H_0\\approx72.38^{
 +0.98}_{-1.10}~{\\rm km\\\, s^{-1}\\\, Mpc^{-1}}$\, $S_8=0.785\\pm0.012$\,
  and $M_B=-19.290^{+0.026}_{-0.029}$\, all of which are consistent with th
 eir local measurements\, and moreover that the physical baryon density val
 ue\, $\\omega_b$\, better agrees with the BBN constraints on it and $H(z)$
  exhibits excellent fit to the Ly-$\\alpha$ data. While using the CMB+Pan+
 Ly-$\\alpha$ data set provides us with the similar constrains\, inclusion 
 of the low-redshift BAO data\, i.e.\, using CMB+Pan+BAO data set\, leads t
 o some compromise in these improvements. We will close the talk with a dis
 cussion on some other observational aspects and theoretical implications o
 f the $\\Lambda_{\\rm s}$CDM model. This talk is based on the works ``Grad
 uated dark energy: Observational hints of a spontaneous sign switch in the
  cosmological constant" [Akarsu\, Barrow\, Escamilla\, and Vazquez\, PRD 1
 01 (2020) 063528]\, ``Relaxing cosmological tensions with a sign switching
  cosmological constant" [Akarsu\, Kumar\, Ozulker\, and Vazquez\, PRD 104 
 (2021) 123512]\, and ``Relaxing cosmological tensions with a sign switchin
 g cosmological constant: Improved results with Planck\, BAO and Pantheon d
 ata" [Akarsu\, Kumar\, Ozulker\, Vazquez\, and Yadav\, arXiv:2211.05742] a
 nd several ongoing works by an extended group of leading researchers in th
 e field of cosmology.\n\nhttps://indico.unina.it/event/70/contributions/97
 9/
LOCATION:Lisbon
URL:https://indico.unina.it/event/70/contributions/979/
END:VEVENT
END:VCALENDAR