10 SEP 2024
14:00 - 15:00

Date and time

Tuesday, September 10th, 2024 (Shahrivar 20th, 1403), 2:00 pm (Tehran zone)





Link

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



Abstract
In this talk, I will discuss some properties of the Kerr-Newman (KN) Electromagnetic Fields, which is the G → 0 limit of the KN solution of Einstein-Maxwell equations. In this limit, the electromagnetic sector of the solution survives, while the background becomes locally flat with nontrivial topology. The discussion includes the complex transformation between the non-spinning Coulomb solution and the spinning KN, the g = 2 gyromagnetic ratio of the solution noted by Carter, and the corresponding multipole structure. The topological conserved charges of the electromagnetic field, i.e. the classical helicity and classical spin, are calculated for this solution. Moreover, we studied the interaction of two such solutions by evaluating the Lagrangian for the superposition of those fields. This yields a correction to the interaction potential beyond the Coulomb interaction due to the spin of the fields. The talk is based on: https://arxiv.org/pdf/2405.12602.

9 SEP 2024
11:00 - 12:00

Abstract:

Precise predictions of experimental data at the high energy proton–proton collision are significantly important. Due to the complex nature of proton, where the partons are bound by the strong gluonic force inside the proton, this calculation is not an easy task.
Hence, one cannot calculate the cross section, as simple as, that of the point like particles cross section. Fortunately, the factorization theorem allows us to calculate the cumbersome hadronic differential cross section (DCS) in terms of the elementary partonic cross section, convoluted by the familiar parton distribution functions (PDFs).
In the literature, there can be found different factorization frameworks for calculating the cross section, mostly based on the assumptions of parton behavior inside the proton
, such as the collinear and kt-factorizations (kt is the partonic transverse momentum).
For example, in the collinear factorization, it is assumed that the parton moves collinear to the proton and enters into the hard collision.
Therefore in the collinear factorization theorem, it is supposed that the constituent partons can only have a fraction of the proton momentum, i.e., x,
and these partons do not carry any transverse momentum dependency, i.e. kt.
To describe the distribution of these partons inside the proton, one should use the parton distribution functions (PDFs). However, in the small x limit, the transverse momentum of parton (kt), becomes comparable against the collinear component, i.e., xP (P is the proton momentum). Therefore, the evolution equation of collinear parton, should be generalized by the fact that, parton can also have transverse momentum. This means that the PDFs should have kt dependency. These kt dependent PDFs are called transverse momentum dependent PDFs (TMDs) or unintegrated parton distribution functions (UPDFs).

Link to Join Virtually:
https://meet.google.com/bda-vsem-tuv

28 AUG 2024
11:00 - 12:00

Abstract:

In this talk, I quantify the effects of light spin-zero particles with pseudoscalar couplings to leptons and scalar couplings to nucleons on the evolution of solar neutrinos. I show in this scenario the matter potential sourced by the nucleons in the Sun’s matter gives rise to spin precession of the relativistic neutrino ensemble. For Dirac neutrinos, the spin-flavour precession results in active-sterile oscillations, while for Majorana neutrinos it results in left-handed neutrino to right-handed antineutrino oscillations. In both cases, this leads to distortions in the solar neutrino spectrum which we use to derive constraints on the allowed values of the mediator mass and couplings via a global analysis of the solar neutrino data. In addition for Majorana neutrinos, spin-flavour precession results into a potentially observable flux of solar electron antineutrinos at the Earth which we quantify and constrain with the existing bounds from Borexino and KamLAND.

Indico Link:
https://indico.hep.ipm.ir/e/s.ansarifard1

Link to Join Virtually:
https://meet.google.com/bda-vsem-tuv

28 AUG 2024
09:00 - 10:30

Diagnostic tests that utilize molecular biomarkers in the blood have wide-spread clinical applications. However, early detection of cancer and other devastating diseases is challenging due to the requirement of accurate methods for distinguishing rare molecules carrying disease signals in the background of nondisease associated molecules. Next generation sequencing (NGS) combined with mathematical modelingbased data analysis have proven promising for high accuracy and high throughput diagnostics. Here, I give an overview of the state-of-the-art computational methods that integrate genetic and epigenetic NGS data to extract meaningful signals for diagnosis and disease prevention in cancer screening and other clinical contexts.

This Seminar is free and open to the public.

You can join with this link:

https://www.skyroom.online/ch/arashfj/talk

27 AUG 2024
14:00 - 15:00

Date and time

Tuesday, August 27th, 2024 (Shahrivar 6th, 1403), 2:00 pm (Tehran zone)


Link

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



Abstract
In the Standard Model at high temperatures, anomalous effects contribute to the violation of baryon number ($B$) and lepton number ($L$), separately, while $B-L$ remains conserved. There are also corresponding changes in the helicity of the hypermagnetic field ($h$) and the Chern-Simons numbers of the non-Abelian gauge fields ($N_{\rm CS,W}$ and $N_{\rm CS,S}$). In this study, we investigate a baryogenesis process in the symmetric phase of the early Universe by taking into account the Abelian and non-Abelian anomalous effects as well as the perturbative chirality-flip processes of all fermions. We calculate explicitly the time evolution of all relevant physical quantities, including those of $h$ and $N_{\rm CS,W}$, and show that there is another conserved global charge involving total matter-antimatter asymmetry $B+L$, hypermagnetic helicity $h_B$ and $N_{\rm CS,W}$.

26 AUG 2024
11:00 - 12:00

Abstract:

Recently, a new rearrangement of short-range interactions has been suggested in the 1S0 nucleon-nucleon channel within Chiral Effective Field Theory. This is intended to reproduce the amplitude zero at leading order, and it includes subleading corrections perturbatively in a way that is consistent with renormalization-group invariance. Systematic improvement is shown at next-to-leading order, the obtained results have been fitted empirical phase shifts remarkably well all the way up to the pion-production threshold. An approach in which pions have been integrated out is included, which allows us to present analytic results that also fit phenomenology surprisingly well.

Based on:
https://doi.org/10.48550/arXiv.1704.08524.

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

Link to Join Virtually:
https://meet.google.com/bda-vsem-tuv