Calendar

Nov
17
Gio
From detector hits to final state particles with machine learning (Nilotpal Kakati, Weizmann Institute of Science, Israel) @ Aula 602 e online
Nov 17@11:00 am–12:00 pm

Seminario di Fenomenologia

Particle Flow (PFlow), the task of reconstructing final state particles from the detector readout, is at the heart of Collider physics. The task is quite challenging due to the complex nature of the detector data, which is heterogeneous (tracks, cells, cluster of energies), sparse, and usually originates from a non-uniform detector geometry. The recent advancements in the felid of Machine learning (ML) have suggested new possibilities beyond the scope of traditional parametric approaches to solving this complex task. In the talk, I will show models that use a set of detector hits as inputs and predict a set of reconstructed particles. I will also discuss a few novel approaches with graph-based architectures, and understand how we can combine ML with physical motivations to obtain State-of-the-art performance. I will also discuss how these models are well-suited to tackle generative problems.

Per connettersi a zoom:
Topic: Theory and Pheno seminars
https://infn-it.zoom.us/j/8573185271
Meeting ID: 857 318 5271

Nov
24
Gio
Challenges in cosmic ray physics: galactic sources, antimatter, dark matter (Prof. Fiorenza Donato, Torino U.) @ Aula 601 e online
Nov 24@2:00 pm–3:00 pm

Seminario di Fenomenologia
The unprecedented precision of data cosmic rays and gamma rays challenges
our understanding of the origin and of the behaviour of cosmic rays in the
Galaxy. We will discuss possible interpretations of the nuclear component,
with emphasis payed to the antimatter channels, where a possible
contribution from dark matter annihilation has been argued.
We will critically assess the leptonic component within a multi-messenger
approach, and in connection with the most recent observations in
gamma-rays.

Per connettersi a zoom:
Topic: Theory and Pheno seminars
https://infn-it.zoom.us/j/8573185271
Meeting ID: 857 318 5271

Dic
1
Gio
Higher-dimensional Quantum Spin and Valley Hall Effects in Synthetic Matter (Giandomenico Palumbo, Dublin Institute for Advanced Studies) @ Aula 602 e online
Dic 1@11:00 am–12:00 pm

Seminario di Fisica Teorica

Higher-dimensional topological phases play a key role in understanding the lower-dimensional topological phases and the related topological responses through a dimensional reduction procedure. In this talk, I present a 4+1-D Dirac-type Hamiltonian protected by CP-symmetry, whose 3D boundary supports an odd number of Dirac cones. This system supports (4+1)-D quantum spin and valley Hall effects. A specific perturbation splits each bulk massive Dirac cone into two valleys separated in energy-momentum space with opposite second Chern numbers, in which the 3D boundary modes become a nodal sphere or a Weyl semi-metallic phase. By introducing the electromagnetic (EM) and pseudo-EM fields, exotic topological responses of our system are revealed, which are found to be described by the (4+1)-D mixed Chern-Simons theories in the low-energy regime. Notably, several topological phase transitions occur when the bulk gap closes by giving rise to exotic double-nodal-line/nodal-hyper-torus gapless phases. Finally, I show how to probe experimentally these topological effects in cold atoms.

Per connettersi a zoom
Topic: Theory and Pheno seminars
https://infn-it.zoom.us/j/8573185271
Meeting ID: 857 318 5271

Dic
2
Ven
Joint Analysis Center progress in hadron spectroscopy (Prof. Adam Szczepaniak, Indiana University) @ Aula 605
Dic 2@11:00 am–12:00 pm

Seminario generale

In this seminar, Prof. A.Szcepaniak will present the current activity of JLab Joint Physics Analysis Center (JPAC) concerning the analysis of hadronic resonances in data set s from GLUE, CLAS12, LHCb, BESIII, and COMPASS. Plans and opportunities for the foreseen upgrade in the energy of the CEBAF accelerator, 20+ GeV, will also be discussed.

Dic
16
Ven
Scattering Amplitudes: Mathematical Methods and Novel Results (Giulio Gambuti, Oxford U.) @ Aula 500 e online
Dic 16@2:00 pm–3:00 pm

Seminario di Fisica Teorica

Scattering amplitudes provide a window on the mathematical structure of Quantum Field Theory and serve as a bridge between theoretical predictions and experimental data. Because of this, their computation is of interest to many different research areas. Although much progress has been made in the last few decades, it remains very hard to compute scattering amplitudes at higher orders in perturbation theory. I will describe modern mathematical methods for the analytic computation of amplitudes in a general QFT. As a direct example and application, I will present new three-loop results which, for the first time, allowed a direct extraction of the quadrupole radiation contribution to the infrared structure of QCD. I will conclude with a description of the high-energy (Regge) limit and the first computation of the three-loop gluon Regge trajectory.

Per connettersi a zoom
Topic: Theory and Pheno seminars
https://infn-it.zoom.us/j/8573185271
Meeting ID: 857 318 5271

Feb
2
Gio
Vector boson fusion production of new physics at current and future colliders (Timothy Martonhelyi, Università di Melbourne) @ Aula 500 e online
Feb 2@3:00 pm–4:00 pm

Seminario di Fenomenologia

We clarify the role of vector boson fusion (VBF) in the production of heavy vector triplets at the LHC and the HL-⁠LHC. We point out that the presence of VBF production leads to an unavoidable rate of Drell-⁠Yan
(DY) production and highlight the subtle interplay between the falling parton luminosities and the increasing importance of VBF production
as the heavy vector mass increases. We discuss current LHC searches and
HL-⁠LHC projections in di-⁠boson and di-⁠lepton final states and demonstrate that VBF production outperforms DY production for resonance masses above 1 TeV in certain regions of the parameter space. We define two benchmark parameter points which provide
competitive production rates in vector boson fusion.

Per connettersi a zoom:
Topic: Theory and Pheno seminars
https://infn-it.zoom.us/j/8573185271
Meeting ID: 857 318 5271

Feb
15
Mer
Inferring the impact of feedback on the matter distribution using the Sunyaev Zel’dovich effect (Dr. Shivam Pandey, Columbia University, NY) @ A603 e online
Feb 15@2:00 pm–3:00 pm

Seminario di Fenomenologia

Feedback from active galactic nuclei and stellar processes changes the matter distribution on small scales, leading to significant systematic uncertainty in weak lensing constraints on cosmology. In this talk, I will describe how the observable properties of group-scale halos can be used to constrain the impact of feedback on the matter distribution using Cosmology and Astrophysics with Machine Learning Simulations (CAMELS). By extending the results of previous work to smaller halo masses and higher wave numbers, k, we find that the baryon fraction in halos contains valuable information about the impact of feedback on the matter power spectrum. We will also explore how the thermal Sunyaev Zel’dovich (tSZ) signal from group-scale halos can provide similar information. Using recent Dark Energy Survey (DES) weak lensing and Atacama Cosmology Telescope (ACT) tSZ cross-correlation measurements and models trained on CAMELS, we obtain 10% constraints on the effects of feedback on the power spectrum at k ~ 5 h/Mpc. I will also demonstrate that with future surveys, it will be possible to constrain baryonic effects on the power spectrum to O(<1%) at k = 1 h/Mpc and O(3%) at k = 5 h/Mpc using the methods introduced here. Per connettersi a zoom: Topic: Theory and Pheno seminars
https://infn-it.zoom.us/j/8573185271
Meeting ID: 857 318 5271

Feb
22
Mer
Charm in the proton (Prof. Stefano Forte, Universitá di Milano) @ 603 e online
Feb 22@2:00 pm–3:00 pm

Seminario di Fenomenologia

I present the first clear evidence for the presence of an intrinsic charm component in the proton. I recall the meaning of intrinsic charm and how intrinsic and perturbative charm can be distinguished from each other. I briefly review the NNPDF4.0 determination of the structure of the proton, and I discuss how its results, together with recent advanced tools for the evolution and matching of parton distributions, can be used for a separation of the perturbative and intrinsic charm components and a determination of the latter. I present results for the intrinsic charm component, I compare them to models, I discuss which current data have animpact on it, and briefly examine ongoing future improvements of the current result.

Per connettersi a zoom:
Topic: Theory and Pheno seminars
https://infn-it.zoom.us/j/8573185271
Meeting ID: 857 318 5271

Feb
28
Mar
Signal-background interference effects in Higgs-mediated diphoton production beyond NLO (Federica Devoto, Oxford U.) @ 605 e online
Feb 28@2:00 pm–3:00 pm

Seminario di Fenomenologia

In this talk I will consider signal-background interference effects in Higgs-mediated diphoton production at the LHC. The inclusion of such effects results in a shift of the diphoton invariant mass distribution and in a destructive contribution to the total cross section. As pointed out in earlier works, one can exploit interference studies to put bounds on the Higgs boson decay width. After reviewing the Higgs interferometry framework I will present an extension of this analysis up to NNLO QCD in the soft-virtual approximation.

Per connettersi a zoom:
Topic: Theory and Pheno seminars
https://infn-it.zoom.us/j/8573185271
Meeting ID: 857 318 5271

Giu
21
Mer
Gluon scattering in AdS from supersymmetric localization (Pietro Ferrero – Simons Center) @ 602
Giu 21@2:00 pm–3:00 pm

Seminario di Fisica Teorica INFN/DIFI

I will discuss some of the recent progress made in the computation of holographic correlators describing the scattering of gluons in anti de Sitter space. I will focus in particular on a special AdS_5 model, arising from N D3 branes probing a D7 brane singularity, which is the holographic description of a certain 4d N=2 USp(2N) gauge theory with matter. The (mass-deformed) partition function of such gauge theory gives a non-perturbative integral constraint that the holographic correlators must satisfy, thus allowing to fix a number of coefficients that cannot be obtained from bootstrap considerations alone. Among our results: we obtain a finite coupling expression for the first higher-derivative corrections in terms of modular functions, we derive the first three orders in the small alpha’ expansion of the Veneziano amplitude in AdS_5xS^3 and we completely fix a one-loop ambiguity in the gluon amplitude without a reference to the effective action on the D7 branes, which is not known.