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 Fisica Teorica –
Over the past two decades, f(R) gravity has been at the forefront of providing an alternative to dynamical dark energy to explain the origin of late-time acceleration in the universe. This talk will provide a survey of work that has been done in this area using covariant methods, dealing with diverse topics from cosmological dynamics to gravitational lensing and perturbations of black holes.
Per connettersi a zoom:
https://infn-it.zoom.us/j/93341311520?pwd=RklTcFFVWjdtUzR5TUZKM3V1TjJiQT09
Seminario di Fisica Teorica-
In the first part of the presentation, I will present a study of the spectra and strong decay widths of heavy baryons. The masses of single heavy baryons up to the D-wave have been calculated within a constituent quark model, employing both the three-quark and quark-diquark schemes. The decay widths of the ground and excited single heavy baryons into the heavy single baryon-(vector/pseudoscalar) meson pairs and the (octet/ decuplet) baryon-
(pseudoscalar/vector) heavy meson pairs, have been calculated. Moreover, I will discuss why the presence or absence of the ρ-mode excitations in the experimental spectrum is the key to distinguishing between the quark-diquark and three-quark behaviours, as it was originally pointed out in. The quantum number assignments and predictions for mass spectra and strong-decay widths are in agreement with the available data. These findings provide valuable
guidance for future measurements in experiments as ATLAS, CMS, LHCb, Belle, and Belle II.
In the second part of this talk, I will present a new application of the Interacting Boson Fermion-Fermion Model (IBFFM) for describing double charge exchange reactions. The study of double charge exchange reactions induced by heavy ions involving candidate nuclei for neutrinoless double beta decay is a complex task carried out by the NUMEN collaboration [5], to which I belong. This investigation faces the intricacies of complex odd-odd intermediate nuclei in sequential double charge exchange processes. I will offer a comprehensive description of heavy odd-odd nuclei using the (IBFFM). Additionally, I will outline the methodology for describing transfer operators within this framework.
Finally, I will explore the potential applications of our results in future reaction codes for describing double charge exchange reactions.
Per connettersi a zoom:
https://infn-it.zoom.us/j/93341311520?pwd=RklTcFFVWjdtUzR5TUZKM3V1TjJiQT09
Seminario di Fisica Teorica-
The advent of noisy-intermediate-scale quantum (NISQ) devices is opening new horizons for fundamental theoretical research. When viewed as experimental platforms for many-body quantum physics, NISQ devices can be conceptualized as systems evolving according to discrete sequences of few-body unitary processes, local projective measurements, and feedback. These ingredients give rise to new qualitative features and universal phenomena out of equilibrium, such as the recently discovered entanglement measurement-induced phase transitions (MIPTs). In the first part of the talk, I will provide an overview of the recent literature on the subject, introducing different quantum-circuit models for non-equilibrium many-body physics and the MITPs. In the second part, I will focus on some of my recent work on explicit models, showing either interesting new phenomena or allowing for analytic insight based on mappings to statistical mechanics problems.
Per connettersi a zoom:
https://infn-it.zoom.us/j/93341311520?pwd=RklTcFFVWjdtUzR5TUZKM3V1TjJiQT09
Seminario di Fenomenologia –
In this talk I will describe how the common treatment of heavy quark mass effects in either the initial of final state can lead to important issues and how can we construct a more effective way of dealing with massive quarks in a consistent way both theoretically and practically.
Per connettersi a zoom:
https://infn-it.zoom.us/j/93341311520?pwd=RklTcFFVWjdtUzR5TUZKM3V1TjJiQT09
Seminario Generale
The Precision Proton Spectrometer (PPS) was developed by the CMS and TOTEM Collaborations and started to be used extensively during Run 2 of the LHC. It is a powerful tool for advancing new measurements with forward proton tags and beyond the standard model searches. The commissioning of this new detector involves understanding different aspects of forward proton reconstruction (alignment and optics calibrations, radiation damage, pileup contributions and validation using standard model candles).
In this seminar I’ll illustrate how PPS can be used by focussing on a generic search for the associated production of a Z boson or a photon with an additional unspecified massive particle X in proton-tagged events from proton-proton (pp) collisions at √s =13 TeV, recorded in 2017. The so-called missing mass spectrum is analysed in the 600–1600 GeV range and a fit is performed to search for possible deviations from the background expectation. No significant resonant deviations in data with respect to the background predictions have been observed. Model-independent upper limits on the visible production cross section of pp → pp + Z/γ + X are set. Results from other recent searches with PPS and Run 2 will also be summarized.