Seminario di Fisica Teorica
It has became clear that the landscape of possible effective field theories arising from string compactifications is vast. On the other hand, in the last 20 years it has been shown that it represents only a small part of the possible QFTs coupled to gravity one may imagine. The reason is, as shown by the seminal work by Vafa and Ooguri, that most QFTs when coupled to gravity develop subtle inconsistencies and for that they can’t appear as effective field theories of a consistent theory of quantum gravity. The space of such theories as been called the “swampland”, in opposition to the landscape, and the conditions they fail to satisfy “swampland conjectures”. In this talk, I will give first a review of the swampland program and the main swampland conjectures, explaining the arguments that justify them, and then show recent results obtained with Martucci and Weigand about constraints on N=1 d=4 theories coming from the existence of peculiar extended objects in their spectrum we called “EFT strings”. In particular, we will be able to derive upper bounds on the possible rank of the gauge group of the 4 dimensional theory and check the validity of this claim in a large number of explicit string theory constructions.
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Topic: Theory and Pheno seminars
https://infn-it.zoom.us/j/8573185271
Meeting ID: 857 318 5271
Seminario di Fenomenologia
Recently, JPAC collaboration has developed and benchmarked a systematic approach to use Deep Neural Networks as a model-independent tool to analyze and interpret experimental data and to determine the nature of an exotic hadron. Specifically, we studied the line shape of the Pc(4312) signal reported by the LHCb collaboration. This novel method presents great potential and can be applied to other near-threshold resonance candidates.
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Topic: Theory and Pheno seminars
https://infn-it.zoom.us/j/8573185271
Meeting ID: 857 318 5271
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.
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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.
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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.
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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.
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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.
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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.
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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