14 JUN 2021
11:00 - 12:00

Based on
https://arxiv.org/abs/2103.12226


Abstract: Over the past five years, modern machine learning has been quietly revolutionizing particle physics. Old methodology is being outdated and entirely new ways of thinking about data are becoming commonplace. This article will review some aspects of the natural synergy between modern machine learning and particle physics, focusing on applications at the Large Hadron Collider. A sampling of examples is given, from signal/background discrimination tasks using supervised learning to direct data-driven approaches. Some comments on persistent challenges and possible future directions for the field are included at the end.


https://meet.google.com/anh-ditu-htd

9 JUN 2021
13:30 - 15:00

The interstellar medium (ISM) is referred to as the ''gasses between stars'' within a galaxy. The ISM has quite various physics and chemistry, where to include the environments with a temperature of a few million Kelvin to pretty cool areas. Because of the young star activities in addition to the mass ejection of old stars, and of course, supernova explosions, several atoms, molecules, and compounds are found in the ISM. Neutral gases can be observed in this environment as well as very hot and highly ionized clouds. The ISM is the birthplace of all-stars of space and therefore its study tells us stories about a wide range of mysteries from the formation of large galaxies to life creation on a planet like Earth. In this talk, I'll discuss a group of extremely heavy molecules whose chemical structures have not been discovered for 100 years. I'll show some new molecules discovered in a very high-quality EDIBLES survey as well as some time variations of them.

9 JUN 2021
11:00 - 12:00

Abstract: Lepton flavor violating interactions are absent in the standard model but are expected in various beyond standard models. In this work, the potential of the future circular electron-positron collider to probe the four fermion lepton flavor couplings via the e+e- → e τ process is revisited by means of an effective field theory approach. We provide constraints at 95% CL on the dimension-six Wilson coefficients including major sources of background processes and considering realistic detector effects at four expected operation energies of 157.5, 162.5, 240 and 365 GeV according to their corresponding integrated luminosities. We demonstrate that statistical combination of the results from four center-of-mass energies, improve the sensitivity to the LFV couplings significantly. We compare the results with the prospects from Belle II with 50 ab^-1 and other studies at electron-positron colliders.


Indico: https://indico.particles.ipm.ir/indico/event/412

https://meet.google.com/vax-dyjg-wju

9 JUN 2021
14:00 - 15:00

Abstract:
Active particles include a wide range of artificial self-propellers and biological swimmers that consume ambient free energy to facilitate their persistent, active, motion. Active Brownian particles constitute a basic model to approximate the swimming motion. These self-propelled particles are typically assumed to move at constant speed, while they are also subject to translational and rotational Brownian (thermal) noise and interaction forces from other surrounding objects in the medium. Study of active Brownian particles and their response to different forms of external stimuli, e.g., fluid flow and external chemical/ magnetic fields, has found a wide range of applications in phenomena such as rheotaxis, chemotaxis and magnetotaxis of artificial or biological swimmers. We explore the nonequilibrium, steady-state, dynamics of non-interacting, active and passive, spheroidal Brownian particles subject to channel flow and external fields. We use a continuum probabilistic approach, by studying the solutions of a Smoluchowski equation, governing the joint position-orientation probability distribution function of the spheroidal particles. The solutions of Smoluchowski equation are obtained numerically using finite-element methods. In the case of active magnetic spheroids subject to Couette flow and downward magnetic field, our results include: (i) linear response of prolate and oblate swimmers under weak magnetic fields, in terms of their migration to lower half of the channel; (ii) reverse migration of oblate swimmers under intermediate magnetic fields; and (iii) upstream swimming of prolate, as well as, oblate swimmers when subject to strong magnetic fields. The study of passive magnetic spheroids subject to Poiseuille flow and inclined magnetic fields focuses on the effects of rotational dynamics of passive spheroids and particlewall hydrodynamic interactions. We find that (i) the wall-induced lift velocity focuses the pinned prolate/oblate spheroids in the upper/lower halves of the channel; (ii) the spread of the density peak of focused spheroids around the focusing latitude is dependent on the field-inclination angle and the ratio of the field-to-shear strength, as well as, thermal effects that decrease by increasing the individual magnetic field/shear strengths; and finally, (iii) optimal focusing, achieved under certain ranges of field inclination angles, can be used for efficient shape-based separation of magnetic spheroids.

Date: Wednesday, June 9, 2021

Time: 14:00-15:00

To join the webinar, please follow this link:
https://www.skyroom.online/ch/schoolofphysics/condensed-matter-and-statistical-physics
and log in as guest.

Organized by: Condensed Matter and Statistical Physics Group, School of Physics (IPM)

Queries about this event should be addressed to Dr. A. Faridi at azadeh.faridi@ipm.ir

8 JUN 2021
14:00 - 15:00

Abstract:

In this talk thermodynamics of z = 4 Hořava-Lifshitz black holes in 3+1 dimensions will be presented in extended phase space. By using the scaling argument we will find the Smarr relation and the first law for the black hole solutions of z = 4 Hořava-Lifshitz gravity. We will find that it is necessary to take into account the variation of dimensionful parameters of the theory in the first law. We will also find that the reverse isoperimetric inequality can be violated for spherical, flat, and hyperbolic horizons and in all such cases we have black holes for which the specific heat at constant pressure and volume are positive. This provides a counterexample to a recent conjecture stating that black holes violating the reverse isoperimetric inequality are thermodynamically unstable. We will find for z = 4 Hořava-Lifshitz black holes with hyperbolic horizons that there are two critical points: one showing Van der Waals behavior, the other reverse Van der Waals behavior.


Date: Tuesday, June 8th

2 p.m. - 3 p.m. (Tehran time)





Zoom. (click)

Meeting ID: 881 3325 0645

Passcode: 078775

8 JUN 2021
17:00 - 18:00

Abstract: I review the exotic RG flow in Einstein-Hilbert gravity and talk about the detail of our recent work 2105.13208v1. By considering the general quadratic curvature corrections, we examine the formal and the possible new critical points of this theory. In other words, we find the critical points of the RG flow near the local minima and maxima of the potential of the matter field and show the existence of the bounce solutions by using the superpotential approach. In addition to the former constraints on the superpotential values, there are new ones and the RG flow is controlled by singular curves. This study may shed some light on how a c-function can exist in the presence of these corrections.

8 JUN 2021
16:00 - 18:00

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2 JUN 2021
11:00 - 12:00

Abstract: We refine an earlier introduced 5-dimensional gravity solution capable of holographically capturing several qualitative aspects of (lattice) QCD in a strong magnetic background such as the anisotropic behavior of the string tension, inverse catalysis at the level of the deconfinement transition or sensitivity of the entanglement entropy to the latter. Here, we consistently modify our solution of the considered Einstein-Maxwell-dilaton system to not only overcome an unphysical flattening at large distances in the quark-antiquark potential plaguing earlier work, but also to encapsulate inverse catalysis for the chiral transition in the probe approximation. This brings our dynamical holographic QCD model yet again closer to a stage at which it can be used to predict magnetic QCD quantities not directly computable via lattice techniques.


Phys. Rev. D 103, 086021 (2021), [arXiv:2010.04578 [hep-th]]

Indico: https://indico.particles.ipm.ir/indico/event/409
https://meet.google.com/vax-dyjg-wju

2 JUN 2021
13:30 - 15:00

In this talk, I will briefly introduce some concepts associated to ``multiverse” and discuss new challenges of doing science in this context. I will also argue for (and against) some proposals to overcome these challenges.