31 MAY 2023
16:00 - 17:00

We discuss two notions of percolation on graphs. The first one is $r$-neighbor bootstrap percolation in which an activation process of the vertices of a given graph is carried out. The process starts with some initially activated vertices and then, in each round, any inactive vertex with at least $r$ active neighbors becomes activated. The second one is the so called graph bootstrap percolation in which we activate the edges of a graph instead of vertices. Starting with some initially activated edges, we activate any inactive edge which creates a new copy of $H$, the pattern or base graph. Two problems, one of combinatorial nature and the other of probabilistic type are reviewed. The minimum size of a set of initially activated vertices leading to the activation of all vertices of a graph $G$ in the $r$-neighbor bootstrap percolation is denoted by $m(G, r)$. Computing $m(G, r)$ is a combinatorial problem. In the second problem, each vertex of $G$ is initially activated with a probability $p$ and the question is to find the probability threshold of activation of all vertices of the graph $G$. We talk about the latest developments on both problems and also the connections between $r$-neighbor bootstrap percolation and graph bootstrap percolation.

Subscribing the Mathematics Colloquium mailing list:
https://groups.google.com/g/ipm-math-colloquium

31 MAY 2023
17:30 - 19:00

I will present joint work with Andrea Ferraguti which makes progress on a conjecture of Andrews and Petsche that classifies abelian dynamical Galois groups over number fields, in the unicritical case. I will explain how to reduce the conjecture to the post-critically finite case and the key tools to handle all unicritical PCF with periodic critical orbit over any number field and all PCF over quadratic number fields. Along the way I will present an earlier rigidity result of ours on the maximal closed subgroup of the automorphism group of a binary rooted tree, which offered us with the main input to translate the commutativity of the Galois image into diophantine equations. I will also overview progress on the tightly related problem of lower bounding arboreal degrees.

Zoom Meeting ID: 856 1386 0958
Passcode: 513992
ICS-File: https://researchseminars.org/seminar/FGC-IPM/ics

31 MAY 2023
13:30 - 15:00

The coefficients of the operators of an effective field theory (EFT) are constrained to satisfy certain inequalities, under the (mild) assumption that the UV completion satisfies general requirements of causality and unitarity. We begin the extension of these ideas to theories where the Lorentz symmetry is spontaneously broken, as it happens in cosmology and condensed matter physics. Constraints are derived using dispersive arguments for the 2-point function of conserved currents and of the stress-energy tensor.


To join the seminar, please click on the following link


https://www.skyroom.online/ch/soa/weekly-seminar

29 MAY 2023
16:00 - 18:00

Some Remarks on Coerced Confession

29 MAY 2023
11:00 - 12:00

Abstract:

Cosmic muons are high-energy particles that constantly bombard the Earth's atmosphere from outer space. These particles are created by cosmic rays colliding with atoms in the upper atmosphere, and are capable of penetrating deep underground and through dense materials such as lead and concrete. This feature makes them an excellent tool for imaging and exploration. In this work we have brief review on the source of the cosmic muons and their properties, then we discuss their application in imaging and at the end we introduce an optimal detector that has been developed in IPM (Institute for Research in Fundamental Sciences) of Iran for imaging.

Based on:
https://doi:10.1088/1742-6596/1596/1/012008

Meeting Place:
Seminar Room, School of Particles and Accelerators, IPM

Link to join virtually:
https://meet.google.com/fnv-dfkk-ghb

25 MAY 2023
11:00 - 12:00

Abstract:

In this talk, I will first briefly review some quantities which are believed to be the gravity dual of quantum complexity. One of them is generalized volume-complexity which was recently introduced in [arXiv:2111.02429]. This quantity is an extension of volume in the Complexity=Volume (CV) proposal, by adding higher curvature corrections with a coupling constant "lambda" to the volume functional.

Next, I will talk about the calculation of generalized volume-complexity for two-sided Hyperscaling Violating (HV) black branes in "d+2" dimensions for different values of the hyperscaling violation exponent "theta" and dynamical exponent "z". It is observed that the generalized volume-complexity always grows linearly at late times, provided that we choose the coupling constant properly. Moreover, it approaches its late time value from below. I will also discuss the dependence of its growth rate on "d", "theta", "z" and "lambda".

At the end, I will report our results for the complexity of formation obtained from volume-complexity and show that it is not UV divergent. I will also discuss its dependence on the thermal entropy and temperature of the black brane.

This talk is based on:
arXiv: 2207.05287.


Meeting Place:
Seminar Room, School of Particles and Accelerators, IPM

24 MAY 2023
11:00 - 12:00

Abstract:

In this talk, I present our last study in which we use the charged-current Higgs boson production process at future electron-proton colliders, with the subsequent decay of the Higgs boson into a $b\bar{b}$ pair, to probe the Standard Model effective field theory with dimension-six operators involving the Higgs boson and the bottom quark. The study is performed for two proposed future high-energy electron-proton colliders, the Large Hadron Electron Collider (LHeC) and the Future Circular Collider (FCC-he) at the center-of-mass energies of 1.3 TeV and 3.46 TeV, respectively. Constraints on the CP-even and CP-odd couplings are derived by analyzing the simulated signal and background samples. A realistic detector simulation is performed and a multivariate technique using the gradient Boosted Decision Trees algorithm is employed to discriminate the signal from background. Expected limits are obtained at $95\%$ Confidence Level for the LHeC and FCC-he assuming the integrated luminosities of 1, 2 and 10 $ab^{-1}$. We find that using 1 $ab^{-1}$ of data, the CP-even and CP-odd couplings can be constrained with accuracies of the order of $10^{-3}$ and $10^{-2}$, respectively, and a significant region of the unprobed parameter space becomes accessible.

Indico Link:
https://indico.hep.ipm.ir/e/r.jafari

Meeting Place:
Seminar Room, School of Particles and Accelerators, IPM

Link to join virtually:
https://meet.google.com/fnv-dfkk-ghb

24 MAY 2023
17:30 - 19:00

I will survey some recent developments regarding the minimal model program for foliations defined over a complex algebraic variety, together with some applications towards the study of fibrations in birational geometry.

https://zoom.us/join
Meeting ID: 9086116889
Passcode: 362880

24 MAY 2023
14:00 - 15:00

Argumentation has gained attention in AI disciplines such as game theory, non-monotonic reasoning, and knowledge representation, as well as in fields like philosophy, psychology, and law. Formalisms of argumentation enable the modeling and evaluation of arguments. Our presentation focuses on implementing formalisms of argumentation to assess the quality of online product reviews. Despite the importance of product reviews in decision-making, dealing with numerous inconsistent reviews is challenging. We demonstrate how argumentation formalisms can be used to evaluate the quality of online product reviews.

link: https://room.gharar.ir/ba05e1ad-99f6-4911-b60e-dbf02616a692

24 MAY 2023
13:30 - 15:00

It has been pointed out that nonlinear effects are necessary to model the ringdown stage of the gravitational waveform produced by the merger of two black holes giving rise to a remnant Kerr black hole. We show that this nonlinear behaviour is explained, both on the qualitative and quantitative level, by near-horizon symmetries of the Kerr black hole within the Kerr/CFT correspondence.



To join the seminar, please click on the following link


https://www.skyroom.online/ch/soa/weekly-seminar

23 MAY 2023
14:00 - 15:00

Date and time

Today, 23rd of May 2023 (2nd of Khordad, 1402), 2:00 pm (Tehran zone)



Link

https://www.skyroom.online/ch/schoolofphysics/highenergyseminar



Abstract

The symmetron field has an environment (density) dependent behavior which is a common feature of the models with the screening mechanism and results in a rich phenomenology. This model can produce domain walls between regions with different densities. We consider this aspect and study the physics of domain walls in between (underdensity) voids and (overdensity) halo structures. The (spherical) domain walls exert a repulsive force on a test mass outside of the wall while a test mass inside of the wall sees no force. This makes the structures outside the voids go further to a larger radius. Effectively, this means the voids are becoming larger in this scenario in comparison to the standard model of cosmology. Interestingly, this makes voids emptier which may shed light on Peeble’s void phenomenon.

22 MAY 2023
11:00 - 12:00

Abstract:

Upcoming searches for the stochastic background of inflationary gravitational waves (GWs) offer the exciting possibility to probe the evolution of our Universe prior to Big Bang nucleosynthesis. In this spirit, we explore the sensitivity of future GW observations to a broad class of beyond-the-Standard-Model scenarios that lead to a nonstandard expansion history. We consider a new scalar field whose coherent oscillations dominate the energy density of the Universe at very early times, resulting in a scalar era prior to the standard radiation-dominated era. The imprint of this scalar era on the primordial GW spectrum provides a means to probe well-motivated yet elusive models of particle physics. Our work highlights the complementarity of future GW observatories across the entire range of accessible frequencies.

Based on:
https://arxiv.org/abs/1904.07870

Meeting Place:
Seminar Room, School of Particles and Accelerators, IPM

Link to join virtually:
https://meet.google.com/fnv-dfkk-ghb

18 MAY 2023
-

May 17-18, 2023 (27-28 Ordibehesht 1402)