__Personal Information__

(+30) 26510 - 08451

l.c.kazantzidis@gmail.com

lawrence.kazantzidis

Lavrentios Kazantzidis

Personal Website

**Research Interests**

**Short Curriculum Vitae**

**Education**

**2017 – 2022 Ph.D. in Physics** Thesis Title: “Cosmological Implications of Scalar Tensor Theories”

**Department of Physics, University of Ioannina**

**2015 – 2017 Postgraduate Studies (M.Sc.) in Physics**

Graduated with an overall grade 8.44/10.00

Department of Physics, University of Ioannina

**2011 – 2015 Bachelor of Science certificate (B.Sc.) in Physics**

Graduated with an overall grade 7.47/10.00

Department of Physics, University of Ioannina

**Scholarships/Grants**

**2021 – Present Tilted Cosmology** Role: Partner

**Funding Source: Hellenic Foundation of Research and Innovation (HFRI) – “1st Call for Hellenic Foundation for Research and**

Innovation Research Projects to support Faculty members and Researchers and the procurement of high-cost research equipment”.

**2018 – 2021 Cosmological Aspects of Modified Theories of Gravity**

Fellow of the Greek State Scholarships Foundation (IKY) for Ph.D. Studies.

**Computer Skills**

**Operating Systems Windows & LinuxProgramming C & Wolfram MathematicaScientific Software (MG)CAMB, (MG)COSMOMC, CLASS, MontePython, LaTeX**

**Languages**

**Greek NativeEnglish First Certificate in English (FCE) Examination for the Certificate of Competency in English (ECCE)French Diplôme d’études en langue française (DELF) B1**

**Collaborations **

**2021 – 2022 Snowmass2022 **

**2017 – 2021 Cosmology and Astrophysics Network for Theoretical Advances and Training Actions (CANTATA)**

**Peer Review **

**Societies**

**2018 – Present Junior Member of the Hellenic Society on Relativity, Gravitation and Cosmology**

**Publication Record**

For the full list of my publications please visit the inspirehep database.

**Cosmology Intertwined: A Review of the Particle Physics, Astrophysics, and Cosmology Associated with the Cosmological Tensions and Anomalies**E. Di Valentino et al., Contribution to the 2022 Snowmass Summer Study

*JHEAp*34 (2022) 49-211DOI: 10.1016/j.jheap.2022.04.002

**Observational constraints on the deceleration parameter in a tilted universe**K. Asvesta, L. Kazantzidis, L. Perivolaropoulos and C. G. Tsagas

*Mon.Not.Roy.Astron.Soc. 513 (2022) 2, 2394-2406*

DOI: 10.1093/mnras/stac922, Supplemental Material

**Late-transition vs smooth H(z) deformation models for the resolution of the Hubble crisis**G. Alestas, D. Camarena, E. Di Valentino, L. Kazantzidis, V. Marra, S. Nesseris and L. Perivolaropoulos

*Phys. Rev. D 105, 063538*

DOI: 10.1103/PhysRevD.105.063538, Supplemental Material

**A w – M phantom transition at z_{t}<0.1 as a resolution of the Hubble tension **G. Alestas, L. Kazantzidis, L. Perivolaropoulos

*Phys.Rev.D 103 (2021) 8, 083517*

DOI: 10.1103/PhysRevD.103.083517, Supplemental Material

**Hints for possible low redshift oscillation around the best fit ΛCDM model in the expansion history of the universe**

L. Kazantzidis, H. Koo, S. Nesseris, L. Perivolaropoulos, A. Shafieloo*Mon.Not.Roy.Astron.Soc. 501 (2021) 3, 3421-3426*DOI: 10.1093/mnras/staa3866

** H_{0 }tension, phantom dark energy, and cosmological parameter degeneracies**G. Alestas, L. Kazantzidis, L. Perivolaropoulos

*Phys.Rev.D 101 (2020) 12, 123516*

DOI: 10.1103/PhysRevD.101.123516, Supplemental Material

**Hints of a Local Matter Underdensity or Modified Gravity in the Low z Pantheon data**L. Kazantzidis, L. Perivolaropoulos

*Phys.Rev.D 102 (2020) 2, 023520*

*DOI: 10.1103/PhysRevD.102.023520, Supplemental Material*

**Hints of modified gravity in cosmos and in the lab?**Leandros Perivolaropoulos, Lavrentios Kazantzidis

*Int.J.Mod.Phys.D*

*28 (2019) 05, 1942001, Invited Review for Special Issue on Modified Gravity*

DOI: 10.1142/S021827181942001X

**Constraining power of cosmological observables: blind redshift spots and optimal ranges**L. Kazantzidis, L. Perivolaropoulos, F. Skara

*Phys.Rev.D 99 (2019) 6, 063537*

DOI: 10.1103/PhysRevD.99.063537, Supplemental Material

**σ_{8 }Tension. Is gravity getting weaker at low z? Observational evidence and theoretical implications**Lavrentios Kazantzidis, Leandros Perivolaropoulos

*Invited contribution for the White Paper of COST CA-15117 project “CANTATA” (Cosmology and Astrophysics Network for Theoretical Advances and Training Actions) “Observational Discriminators” section.*

DOI: 10.1007/978-3-030-83715-0_33, arXiv: 1907.03176, Supplemental Material

**Consistency of modified gravity with a decreasing G_{eff} (z) in a ΛCDM background**Radouane Gannouji, Lavrentios Kazantzidis, Leandros Perivolaropoulos, David Polarski

*Phys.Rev.D 98 (2018) 10, 104044*

DOI: 10.1103/PhysRevD.98.104044, Supplemental Material

**Evolution of the fσ_{8}**

**tension with the Planck15/ΛCDM determination and implications for modified gravity theories**

Lavrentios Kazantzidis, Leandros Perivolaropoulos

*Phys.Rev.D 97 (2018) 10, 103503*

DOI: 10.1103/PhysRevD.97.103503, Supplemental Material

**Experience**

**Teaching Assistance**

**Winter Semesters 2017 – 2022 Classical Electrodynamics I (5th Semester Core Course – 52)** Department of Physics, University of Ioannina, Greece

**Spring Semesters 2020 – 2022 Cosmology (Advanced Undergraduate Elective Course – 105)**

Department of Physics, University of Ioannina, Greece

**Spring Semesters 2018 – 2019 Gravity and Cosmology (Advanced Graduate Elective Course – M122)**

Department of Physics, University of Ioannina, Greece

**M.Sc. Diploma Thesis**

**Title: **Dark Energy from Generalized Gravitational Theories with a Time-dependent Newton’s Constant (scalar tensor theories).**Abstract: **This work is focused on alternative forms of Dark Energy. The challenges that the ΛCDM model faces led to a variety of alternative models, such as extra dimensions, quintessence models, $f(R)$ extended gravity theories, scalar tensor quintessence models etc. The main goal of my master thesis is to investigate the cosmological dynamics for general scalar tensor quintessence field models. Firstly, we introduce the reader to the mathematical formalism of Standard Cosmology and then, we study alternative theories that can play the role of Dark Energy such as quintessence models based on linear-negative potentials of the form $V (\phi) = −s \, \phi$. In the second part of this work we review the scalar tensor quintessence field models and their theoretical background. We investigate the equation of state parameter $w(z)$ for these particular models and we use the Union2.1 dataset of 580 SnIa as a validity test and to explore the observational consistency of the theoretical model and its predictions for the fate of our Universe. Finally we study qualitatively different potentials of the form $V = s \, |\phi|^{n}$ and use, once again the Union2.1 dataset as a consistency test of our model.

You can see my full M.Sc. thesis here.

Ph.D. Thesis

**Title: **Cosmological Implications of Scalar Tensor Theories**Abstract: **In this PhD dissertation we study the cosmological consequences of modified theories of gravity. Motivated by the theoretical and observational challenges of the concordance model ΛCDM, we use up to date cosmological data from both geometric and dynamical probes to constrain modified gravity theories and extract the relevant best fit parameters. In particular, we first introduce the reader to the mathematical formalism of standard cosmology and then focusing on one of the two major tensions that ΛCDM faces ($\sigma_8$ tension), we introduce a purely phenomenological parametrization for the evolving Newton’s constant $G_{\rm eff}$ and constructing an up to date compilation of growth data we extract its best fit parameters. Then, we study viable modified theories of gravities (such as f(R) and scalar tensor theories) in order to see if they have the potential to support the observed behavior the evolving Newton’s constant. Moreover, we examine other cosmological data (such as the low l cosmic microwave background data as well as the Pantheon compilation, i.e. the latest publicly available Type Ia supenovae compilation that is publicly available) to impose strong constraints on the phenomenological parametrization for $G_{\rm eff}$. Next, we study the constraining power (sensitivity) of a wide range of cosmological observables on cosmological parameters, showing that the sensitivity is actually a rapidly varying function of the redshift where the observable is measured and not a monotonically increasing function. In addition, we consider two late time gravitational transition dark energy models that have the ability to simultaneously tackle both the $H_0$ and growth problems and using the full cosmic microwave background data as well as some other up to date cosmological data, we obtain their quality of fit and compare it with the quality of fit provided by other well studied dark energy models that have been proposed as possible solutions in the literature as well as with the concordance model of standard cosmology. Finally, we study the impact of various modified gravity models in the sub-mm scales using the data of the Washington experiment.

You can see my full Ph.D. thesis here.