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

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

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

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.

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

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

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

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.

Topic: Theory and Pheno seminars

https://infn-it.zoom.us/j/8573185271

Meeting ID: 857 318 5271

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.

Topic: Theory and Pheno seminars

https://infn-it.zoom.us/j/8573185271

Meeting ID: 857 318 5271

Seminario di Fenomenologia-

The Standard Model (SM) is an Effective Field Theory (EFT) with an electroweak hierarchy problem associated to an unnaturally light Higgs. After introducing the concept of the SM EFT and the naturalness problem, I will present the possibility that an unnatural hierarchy between certain higher-dimensional operator coefficients in a low-energy EFT would automatically imply that the Higgs’ vacuum expectation value is hierarchically smaller than the EFT cut-off, assuming the EFT emerged from a unitary, causal and local UV completion. Future colliders may have the sensitivity to infer such a pattern of coefficients for a little hierarchy with an EFT cut-off up to O(10) TeV.

Topic: Theory and Pheno seminars

https://infn-it.zoom.us/j/8573185271

Meeting ID: 857 318 5271