Calendar

Gen
1
Gio
Positivity Constraints on Lorentz-breaking EFTs (Paolo Criminelli, ICTP) @ Aula 500 e online
Gen 1 1970@1:00 am–Feb 7 2106@7:28 am

Seminario di Fisica Teorica-

The coefficients of the operators of an effective field theory (EFT) are constrained to satisfy certain inequalities, under the (mild) assumption that the UV completion satisfies general requirements of causality and unitarity. We begin the extension of these ideas to theories where the Lorentz symmetry is spontaneously broken, as it happens in cosmology and condensed matter physics. Constraints are derived using dispersive arguments for the 2-point function of conserved currents and of the stress-energy tensor.

Per connettersi a zoom:

https://infn-it.zoom.us/j/93341311520?pwd=RklTcFFVWjdtUzR5TUZKM3V1TjJiQT09

Nov
11
Gio
Recent jet measurements on ALICE @ Aula 603 e online
Nov 11@11:00 am–12:00 pm

Seminario INFN/DIFI di fenomenologia delle particelle elementari – Dr. Ezra Lesser (UC Berkeley)

In recent years, jet and jet substructure observables have been used at the LHC as instruments to search for new physics as well as to test perturbative and probe non-perturbative processes in QCD. Some observables are infrared and collinear (IRC) safe and thus easily comparable to first-principles calculations, while others offer direct insight into specific physical phenomena such as the quark-gluon plasma (QGP) formed in heavy-ion collisions. The high-precision capability of the ALICE tracking system allows a unique opportunity at LHC energies to measure tracks with low $p_text{T}$, permitting both accessibility to the softer components inside jets as well as measurement of jets with altogether lower pT. This allows ALICE a rare view into QCD and QGP dynamics at pT < 100 GeV/c. We review several recent jet measurements in ALICE using both pp and Pb-Pb collisions at 5.02 TeV and discuss the results. —————————————————————————-
Per partecipare in presenza, prenotarsi seguendo il link
https://docs.google.com/document/d/1uaw5DHG0VykTHraDiAqYjbLFXsrOIXaftj_n04sj4PE/edit?usp=sharing
oppure per partecipare su Zoom, collegarsi al meeting
Topic: Theory and Pheno seminars
https://infn-it.zoom.us/j/8573185271
Meeting ID: 857 318 5271
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Nov
17
Mer
A Finite S-matrix @ on-line
Nov 17@2:00 pm–3:00 pm

Seminario di Fisica Teorica INFN/DIFI – Dr. Holmfridur Hannesdottir (Institute for Advanced Studies – Princeton)

The S-matrix is a fundamental object in quantum field theory, relating theoretical predictions to data from collider experiments. However, in theories with massless particles when interactions between single-particle states prevail at asymptotic times, the S-matrix is infrared (IR) divergent in perturbation theory. In this talk, we explore three solutions to the IR divergence problem: i) summing over initial and final states to obtain a finite cross section, ii) modifying the S-operator, and iii) using coherent states as scattering states. In particular, we exploit the universality of asymptotic evolution to define a modified S-operator in theories with massless particles. The resulting S-matrix can be interpreted as Wilson coefficients in Soft-collinear effective theory, as remainder functions in N=4 super Yang-Mills theory, or as coherent states. Examining its analytic structure thus provides a new probe of familiar objects from scattering calculations.

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Per partecipare su Zoom, collegarsi al meeting
Topic: Theory and Pheno seminars
https://infn-it.zoom.us/j/8573185271
Meeting ID: 857 318 5271
—————————————————————————–

Nov
25
Gio
The X17 anomaly: status and prospects @ online
Nov 25@11:00 am–12:00 pm

Seminario di Fenomenologia delle Particelle Elementari INFN/DIFI – Dr. Enrico Nardi (INFN Laboratori Nazionali di Frascati)

Certain anomalies observed in the angular correlation spectra of
electron/positron pairs produced in nuclear transitions of 8Be, 4He
and 12C can be interpreted as the emission of a bosonic particle with
a mass of 17 MeV, that promptly decays into e+e−. I review the current
status of these anomalies, and some theoretical interpretation for the
hypothetical new particle. I will also describe the prospects for
validating or disproving the X17 hypothesis by means of a particle
physics experiment.

Per partecipare su Zoom, collegarsi al meeting
Topic: Theory and Pheno seminars
https://infn-it.zoom.us/j/8573185271
Meeting ID: 857 318 5271

Nov
29
Lun
CDS @ on-line
Nov 29@2:00 pm–3:00 pm

Consiglio di Sezione

Dic
2
Gio
The ATLAS beauty @ A603 e online
Dic 2@11:00 am–12:00 pm

Seminario di Fenomenologia INFN/DIFI – Prof . Umberto De Sanctis (Roma Tor Vergata)

The ATLAS experiment is one of the four experiments collecting data from proton-proton collision produced by the Large Hadron Collider (LHC) at CERN in Geneva. From 2010 to 2018, ATLAS collected more than 150 fb-1 of data in the Run 1 and Run 2 campaigns. In this talk I will summarise the main results obtained during this period by the ATLAS experiment in the flavour physics domain highlighting the strategies to analyse the huge amount of data available and the physics channels where ATLAS can produce competitive results in comparison with other experiments.
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Per partecipare in presenza, prenotarsi seguendo il link
https://docs.google.com/document/d/1uaw5DHG0VykTHraDiAqYjbLFXsrOIXaftj_n04sj4PE/edit?usp=sharing
oppure per partecipare su Zoom, collegarsi al meeting
Topic: Theory and Pheno seminars
https://infn-it.zoom.us/j/8573185271
Meeting ID: 857 318 5271
—————————————————————————–

Dic
23
Gio
CDS @ on-line
Dic 23@2:00 pm–3:00 pm

Consiglio di Sezione

Mar
3
Gio
Measurement of the W boson mass at LHCb @ on-line
Mar 3@11:00 am–12:00 pm

Seminario di Fenomenologia INFN/DIFI – Mika Vesterinen (Warwick University)

Global fits to precision electroweak data are sensitive to physics beyond the Standard Model but this sensitivity is currently limited by the precision with which the W mass has been directly measured. The most precise measurements of the W mass have been at hadron collider experiments using the kinematic distributions in leptonic W decays. I present the first measurement of the W mass with the LHCb experiment, which is a single-arm small-angle spectrometer experiment at the LHC. I will start with an introduction to the standard model and the precision electroweak observables before describing the challenges in measuring the W mass and the solutions used in LHCb’s measurement. This measurement is based on a subset of the existing LHCb data and I will present an outlook for a more precise measurement with the full dataset, and future combinations with the other LHC experiments.

Per partecipare su Zoom, collegarsi al meeting
Topic: Theory and Pheno seminars
https://infn-it.zoom.us/j/8573185271
Meeting ID: 857 318 5271

Mar
10
Gio
Astrometric techniques for the calibration of the ASTRI Cherenkov telescope @ on-line e Aula 601
Mar 10@11:00 am–12:00 pm

Seminario pheno/astro INFN/DIFI – Dr. Simone Iovenitti (INAF)

ASTRI is an Italian project for the study of Very High-Energy astrophysical phenomena up to 300 TeV and beyond. After the success of the first prototype instrument located in Italy, ASTRI-Horn, the project is entering the realization phase of the MiniArray: 9 identical Cherenkov telescopes working in stereoscopic mode to be installed in Tenerife, Canary Islands. The ASTRI telescopes present a dual-mirror Schwarzschild-Couder optical configuration (never adopted before in gamma-ray astronomy) and a Cherenkov camera based on fast SiPM sensors, able to image the nanosecond atmospheric flashes produced by energetic cosmic photons. Unfortunately, such devices are almost blind to the steady flux of stars in the field of view and consequently the calibration of their pointing represents a technological challenge, also because the compactness of the structure prevents from installing auxiliary monitoring camera sharing the same optical system of the telescope. However, exploiting the so-called Variance method (a statistical algorithm implemented in the ASTRI electronics) the star signal can be successfully recovered by ASTRI (down to ~ 7 mag), offering the potentiality to image the night sky background and meet the demanding pointing requirement (few arc-sec) despite the coarse pixel size of the camera (11 arc-min). To this end, dedicated astrometry techniques have been developed on purpose. Their validation with data from ASTRI-Horn revealed the presence of unexpected systematic errors, demonstrating the importance of such analysis. At present, similar routines for the astrometric calibration of the pointing are being developed to be implemented in the MiniArray, enhancing the accuracy of the whole system.
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Per partecipare in presenza, prenotarsi seguendo il link
https://docs.google.com/document/d/1uaw5DHG0VykTHraDiAqYjbLFXsrOIXaftj_n04sj4PE/edit?usp=sharing
oppure per partecipare su Zoom, collegarsi al meeting
Topic: Theory and Pheno seminars
https://infn-it.zoom.us/j/8573185271
Meeting ID: 857 318 5271

Mar
14
Lun
Increasing the precision of the QCD coupling around the tau mass scale @ Aula 601 e online
Mar 14@2:00 pm–3:00 pm

Seminario di Fenomenologia – Dr. Diogo Boito (Universidade de Sao Paulo/University of Vienna)

The theoretical precision of many crucial observables in the
Standard Model is nowadays limited by our knowledge of QCD parameters.
Determining the strong coupling and quark masses with smaller uncertainties is
therefore a fundamental task in order to match the reduced errors
that are expected from present and future experiments.
Extracting the QCD parameters is not a straightforward task, since
they are not physical observables: theory input is as important as experimental data. I will
discuss recent developments in the precise determination of the strong coupling
around the tau mass scale, which represents one of the most stringent
tests of asymptotic freedom. I will discuss a viable solution to a
long-standing problem related to the renormalization group improvement
of the perturbative series, the interplay between perturbative and
non-perturbative contributions, and the role of recent experimental
data.
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Per partecipare in presenza, prenotarsi seguendo il link
https://docs.google.com/document/d/1uaw5DHG0VykTHraDiAqYjbLFXsrOIXaftj_n04sj4PE/edit?usp=sharing
oppure per partecipare su Zoom, collegarsi al meeting
Topic: Theory and Pheno seminars
https://infn-it.zoom.us/j/8573185271
Meeting ID: 857 318 5271