SCHOOL OF PHYSICS :: Seminars

Seminars

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Tue Feb 18, 2025 (1403/11/30)

	Feb 18 1403/11/30	14:00	Search for CP-violation as a guiding star towards new physics Show Abstract Abstract:Within the relativistic field theory, CPT is proved to be conserved. However, CP can be broken. The violation of CP can induce electric dipole moment for elementary fermions. Indeed, CP is broken in the Standard Model (SM) of particles. However, the predicted value of the electron electric dipole moment within the SM is too small to be resolvable by present and upcoming experiments. In this talk after a short review of the phenomenological impact of CV-violation, I will discuss our project on the CP-violation carried out in collaboration with late Prof. Demir. Lecturer(s): Yasaman Farzan From : School Of Physics, IPM Research Group: HEPCO Group Weekly Seminar More Info. : Link
Tue Feb 11, 2025 (1403/11/23)

	Feb 11 1403/11/23	14:00	What is the origin of cosmological neutrino mass bounds? Background versus perturbations Show Abstract Abstract:The cosmological upper bound on the total neutrino mass is the dominant limit on this fundamental parameter. Recent observations have strongly tightened it, approaching the lower limit set by oscillation data. Understanding its physical origin, robustness, and model-independence becomes pressing. In this seminar I will introduce a novel framework to explicitly separate for the first time the two distinct cosmological neutrino-mass effects. On the one hand, the impact on background evolution, related to the energy in neutrino masses; on the other hand, the "kinematic" impact on perturbations, related to neutrino free-streaming. I will didactically explain how these effects separately modify CMB anisotropies, by introducing two effective masses enclosing background and perturbations effects. I will explain the results of analyzing CMB data in this framework, which show that the neutrino-mass bound is mostly a background measurement, i.e., how the neutrino energy density evolves with time. The results also quantify the difficulty of measuring the neutrino "kinematical" mass, whose bound is relaxed by 3 orders of magnitude. Lecturer(s): Toni Bertolez Martinez From : ICCUB Research Group: HEPCO Group Weekly Seminar More Info. : Link
Tue Feb 04, 2025 (1403/11/16)

	Feb 04 1403/11/16	14:00	Three unique analyses for three new neutrino detectors Show Abstract Abstract:Next-generation neutrino experiments, such as JUNO, Hyper-K, and DUNE, offer new, unique probes into neutrino and beyond the standard model physics. In this talk, I will discuss how each detector's target material (or size) will lead to distinct signatures and how they could be used in new physics and precision studies. For JUNO, we will utilize low-energy neutrino signals in Carbon to discover the atmospheric tau-neutrino flux. For DUNE, nuclear transitions in Argon allow for new and exciting measurements of solar neutrinos Ã la SNO. Finally, for Hyper-K, its size, and sensitivity to low-energy neutrinos will allow it to measure neutrinos coming from dark matter annihilating within Jupiter's core, reaching sensitivities similar to current direct detection experiments. Lecturer(s): Stephan Meighen-Berger From : University of Melbourne Research Group: HEPCO Group Weekly Seminar More Info. : Link
Tue Jan 21, 2025 (1403/11/2)

	Jan 21 1403/11/2	14:13	Dark Acoustic Oscillation Faces the Cosmological Tension Show Abstract Abstract:With the growing precision of cosmological measurements, tensions in the determination of cosmological parameters have arisen that might be the first manifestations of physics going beyond Lambda CDM. We propose a new class of interacting dark sector models, which lead to qualitatively distinct cosmological behavior, dark acoustic oscillation, which can potentially simultaneously address the two most important tensions in cosmological data, the H0 and S8 tensions. The main ingredients in this class of models are self-interacting dark radiation and its dark acoustic oscillation induced by strong interactions with a fraction of dark matter. I will also present the latest results from applying this model across various combinations of cosmological data, illustrating the improvement it provides over Lambda CDM. Lecturer(s): Taewook Youn From : Cornell University, Korea Institute for Advanced Study Research Group: HEPCO Group Weekly Seminar More Info. : Link
Tue Dec 31, 2024 (1403/10/11)

	Dec 31 1403/10/11	14:00	Looping story in early universe cosmology Show Abstract Abstract:We will review the ongoing debates on loop corrections in the multi-phase inflationary universe and their controversial results. Then, we will show that quantum effects can dramatically affect the long CMB-scale modes after regularizing and renormalizing divergences in different stages of inflationary evolution. Lecturer(s): Haidar Sheikhahmadi From : School Of Astronomy, IPM Research Group: HEPCO Group Weekly Seminar More Info. : Link
Tue Dec 17, 2024 (1403/9/27)

	Dec 17 1403/9/27	14:00	Null Boundary Poisson Brackets Show Abstract Abstract:In physics, we often encounter different types of boundaries: spacelike, timelike, and null boundaries. Spacelike boundaries (e.g., constant time slices) are used for initial value problems, while timelike boundaries (e.g., constant radial surfaces) are suited for boundary value problems. Null boundaries are unique because they share characteristics of both, conceptually lying between spacelike and timelike boundaries. Examples include black hole horizons and null infinity in asymptotically flat spacetimes. In this talk, I will discuss Einstein's gravity in the presence of a generic null boundary and examine the structure of Poisson brackets defined on it. Key results include the ultralocal nature of these brackets and the Carrollian structure of the null boundary solution space. Lecturer(s): Vahid Taghiloo From : School Of Physics, IPM Research Group: HEPCO Group Weekly Seminar More Info. : Link
Tue Dec 03, 2024 (1403/9/13)

	Dec 03 1403/9/13	14:00	Entanglement in Lifshitz Fermion Theories Show Abstract Abstract:I will discuss the static entanglement structure in (1+1)-dimensional free Dirac-fermion theory with Lifshitz symmetry, focusing on arbitrary integer dynamical critical exponents. My presentation will examine the behavior of various entanglement measures in both pure and mixed states. I will also highlight the distinctive properties of Dirac-Lifshitz fermions, particularly their locality, which contrasts with the non-local behavior of scalar counterparts and plays a crucial role in shaping their entanglement structure. Lecturer(s): Mohammad Javad Vasli From : University of Guilan Research Group: HEPCO Group Weekly Seminar More Info. : Link
Tue Nov 26, 2024 (1403/9/6)

	Nov 26 1403/9/6	14:00	A Quantum Description of Wave Dark Matter (Arxiv no: 2408.04696) Show Abstract Abstract:In this talk, I will outline a fundamentally quantum description of bosonic dark matter. Following a quantum optics inspired approach, I will show the density operator of dark matter, which takes a mixed Gaussian form over a coherent state basis. This formalism also allows a precise description of quantities related to dark matter coherence. I will further give a continuous description of dark matter through the wave-particle transition, where the density fluctuation in various scales evolves between the two limits, showing a unique behavior near the boundary of these descriptions. Lecturer(s): Dhong Yeon Cheong From : Yonsei University, Seoul, Republic of Korea Research Group: HEPCO Group Weekly Seminar More Info. : Link
Tue Nov 12, 2024 (1403/8/22)

	Nov 12 1403/8/22	14:00	Explicit Entanglement Wedge Reconstruction via Petz Map Show Abstract Abstract:We revisit entanglement wedge reconstruction in AdS/CFT using the Petz recovery channel. In the case of a spherical region on the boundary, we show that the Petz map reproduces the AdS-Rindler HKLL reconstruction. Moreover, for a generic subregion of the boundary, we could obtain the same boundary representation of a local bulk field lies in the entanglement wedge as the one proposed earlier in JLMS paper using properties of the modular flow. Lecturer(s): Niloofar Vardian From : Sharif University of Technology Research Group: HEPCO Group Weekly Seminar More Info. : Link
Tue Nov 05, 2024 (1403/8/15)

	Nov 05 1403/8/15	14:00	The charge and magnetic radii of the nucleons from the generalized parton distributions Show Abstract Abstract:The proton-radius puzzle refers to the discrepancy observed in measurements of the proton's charge radius when using different methods. This inconsistency has prompted extensive research and debate within the physics community, as it challenges the understanding of quantum electrodynamics and the fundamental properties of protons. In the present study, we determine the charge and magnetic radii of the proton and neutron through a global analysis of the generalized parton distributions (GPDs) at zero skewness for the first time. Our results challenge the measurements or analyses in which the nucleon's radii are extracted considering just a particular experiment or observable, or using only data points covering particular kinematic regions. We emphasize that simultaneous analysis of all available experimental data related to the radii of the nucleons would be preferable to determine their exact values. The final results obtained from our analysis by this way are: rpE=0.8558Â±0.0135 fm, rpM=0.8268Â±0.0533 fm, â?¨r2nEâ?©=â??0.1181Â±0.0270 fm2, and rnM=0.8367Â±0.0845 fm. Lecturer(s): Muhammad Goharipour From : School of Physics, IPM Research Group: HEPCO Group Weekly Seminar More Info. : Link
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