Calendar

Ott
28
Gio
Axion dark matter with low-scale inflation @ Aula 603 e online
Ott 28@11:00 am–12:00 pm

Seminario di Fenomenologia delle Particelle Elementari INFN/DIFI – Dr Lorenzo Ubaldi (SISSA)

After a brief introduction to the strong CP problem, I will introduce the axion as a solution and explain how it also provides a cold dark matter candidate. In the second part of my talk I will focus on cosmological scenarios with a low scale of inflation, and discuss a mechanism that can generate enough axion relics to match the observed dark matter abundance even in such scenarios.

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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
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Nov
4
Gio
Exact solutions to Einstein’s field equation coupled to dust @ Aula 603 e online
Nov 4@11:00 am–12:00 pm

Seminario di Fisica Teorica INFN/DIFI – Davide Astesiano (Università dell’Insubria)

To analyze the dynamics of a single spiral galaxy, we will discuss the known class of exact stationary axially-symmetric solutions to Einstein gravity coupled with neutral dust. Differently from the Newtonian description of the same system where all the quantities are completely fixed once the velocity or the matter distribution are known, the class of the relativistic solutions provides additional degrees of freedom, making the applications of this system much more interesting and wide. Up to now, from the relativistic perspective the already proposed models for galaxies are the co-rotating and the differentially rotating model. While in the first case the velocity of the dust satisfies L_u(g) = 0, in the second case it differs from zero. What is interesting about these solutions is that the low energy limits are non equivalent to the Newtonian theory. In particular, the differentially rotating case generalize the known results of Balasin and Grumiller and further highlights the discrepancy between Newtonian theory of gravity and general relativity at low velocities and energy densities. Using these exact solutions, we push forward the idea that the inertia of the gravitational field can simulate dark matter effects. In fact, we show that non co-rotance further reduces the amount of energy density required to explain the rotation curves for spiral galaxies.

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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
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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.

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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
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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
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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
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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