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.

Per connettersi a zoom:

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.

Per connettersi a zoom:

Topic: Theory and Pheno seminars

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

Meeting ID: 857 318 5271

Seminario di Fenomenologia –

Although not being a dedicated heavy-flavour physics experiment at LHC, ATLAS experiment has a wide programme in that field and produces very competitive results. B-physics studies in ATLAS are mainly based on (multi-)muon signatures and benefit from large available statistics of pp collisions, perfect muon system and optimized triggers for B-physics.

An overview ATLAS B-physics opportunities is given, focusing on the triggers and updates made for LHC Run-3.

Selected recent results are discussed then, including onia production measurements and studies of B_c meson which aim at probing the QCD predictions, exotic hadron spectroscopy, and CP violation measurements in B decays, sensitive to possible BSM physics contributions.

Finally, future prospects are outlined for possible B-physics studies with Run-2 and Run-3 data.

Topic: Theory and Pheno seminars

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

Meeting ID: 857 318 5271

Seminario di Fenomenologia –

I shall review novel approaches that I have explored over the years to extract information optimally from varied observations across the electromagnetic spectrum. The aims are varied as well, and in particular I shall discuss: optimising parameter constraints for the concordance cosmological model; testing the inflationary principle through measuring its non-Gaussian imprint on the cosmic large-scale structure; confirming the validity of general relativity on the largest cosmic scales; probing the particle nature of dark matter; and learning about the origin and composition of ultra-high energy cosmic rays.

Topic: Theory and Pheno seminars

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

Meeting ID: 857 318 5271

Seminario di Fenomenologia –

The role of precise nuclear physics theories and models is increasing in neutrino physics. This has been recognized in low-energy neutrino experiments for many years, but recent progress of accelerator-based neutrino oscillation experiments emphasizes the importance of nuclear physics, or many-body nuclear problems. Modern neutrino oscillation experiments, such as T2K and NOvA, require us to simulate nucleon correlations, and this trend will continue with future experiments, including DUNE and Hyper-Kamiokande. Surprisingly, the need of such nuclear theory is everywhere in high-energy particle physics, and new calculations reveal previously ignored connections between nuclear physics and particle physics.

In this talk, I outline the status of neutrino interaction physics, focusing on the 1 to 10 GeV region which is critical to neutrino oscillation experiments. Special attention is paid to the recent developments in nuclear models which made contributions to neutrino physics.

Topic: Theory and Pheno seminars

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

Meeting ID: 857 318 5271