Seminario di Fisica Teorica –

In this talk I will show that the main properties of the fracton quasiparticles can be derived from a generalized covariant Maxwell-like action. Starting from a rank-2 symmetric tensor field, a partially symmetric rank-3 tensor field strength can be built, which obeys a kind of Bianchi identity. The most general action invariant under the covariant “fracton” transformation consists of two independent terms: one describing Linearized Gravity (LG) and the other referable to fractons, a proof of the always suspected relation between fractons and gravitons. I will also discuss that, as claimed in the Literature, the fracton part can be reconduced to a generalized Maxwell theory. In particular, in the covariant generalization of the fracton theory, the equations describing the fracton limited mobility, i.e. the charge and dipole conservation, are not external constraints, but rather consequences of the field equations of motion, hence of the invariant action and, ultimately, of the fracton covariant symmetry.

Per connettersi a zoom:

Topic: Theory and Pheno seminars

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

Meeting ID: 857 318 5271

Seminario di Fenomenologia –

Improved understanding of quantum chromodynamics (QCD) is crucial for advanced precision in LHC data analysis: nearly all LHC collisions used in physics analysis contain jets of hadronic radiation produced by QCD. Jets are reconstructed using signals from the ATLAS inner tracking detector and calorimeters, and calibrated using in situ techniques. Differential cross-section measurements of jets and jet substructure are multi-faceted physics analyses that enable the testing of new theoretical predictions including resummed analytical predictions and higher-accuracy parton shower Monte Carlos. In this seminar, I will review the prospects for extractions of Standard Model parameters from jet substructure, and I will present new measurements of novel event shape observables performed by ATLAS that are constructed using interdisciplinary data-science techniques.

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 INFN/DIFI

We study holographic correlators in 2d with states whose dimensions scale with the central charge. In the 3d bulk, these heavy states create smooth horizonless solutions of supergravity that reduce to black holes in a certain limit. By solving for quadratic perturbations around these backgrounds we compute heavy-heavy-light-light four point functions at strong coupling, and study their behavior as the geometry approaches that of a black hole. We show that in this limit the spectrum of the theory becomes effectively continuous, and the correlator in momentum space develops a branch cut. The discontinuity along the cut has poles at the quasinormal frequencies of the black hole, similarly to what happens for resonances in quantum mechanics.

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 INFN/DIFI

There is an ongoing discussion regarding the presence of a parity-odd term in the trace anomaly of a quantum field theory consisting of a free Weyl fermion in curved spacetime. The term in question is proportional to the Pontryagin density, times an imaginary factor of dangerous astrophysical implications. In this talk, I will begin by recalling some generalities of (trace) anomalies. Afterwards, I will slowly get into the details, exposing the particularities that arise in the case of Weyl fermions. I will state the arguments provided by those who claim that the odd term does exist, as well as the replies by those of us who asseverate the opposite.

Topic: Theory and Pheno seminars

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

Meeting ID: 857 318 5271

Seminario di Fisica Teorica INFN/DIFI

I will discuss some of the recent progress made in the computation of holographic correlators describing the scattering of gluons in anti de Sitter space. I will focus in particular on a special AdS_5 model, arising from N D3 branes probing a D7 brane singularity, which is the holographic description of a certain 4d N=2 USp(2N) gauge theory with matter. The (mass-deformed) partition function of such gauge theory gives a non-perturbative integral constraint that the holographic correlators must satisfy, thus allowing to fix a number of coefficients that cannot be obtained from bootstrap considerations alone. Among our results: we obtain a finite coupling expression for the first higher-derivative corrections in terms of modular functions, we derive the first three orders in the small alpha’ expansion of the Veneziano amplitude in AdS_5xS^3 and we completely fix a one-loop ambiguity in the gluon amplitude without a reference to the effective action on the D7 branes, which is not known.

Seminario di Fenomenologia-

The Standard Model (SM) is an Effective Field Theory (EFT) with an electroweak hierarchy problem associated to an unnaturally light Higgs. After introducing the concept of the SM EFT and the naturalness problem, I will present the possibility that an unnatural hierarchy between certain higher-dimensional operator coefficients in a low-energy EFT would automatically imply that the Higgs’ vacuum expectation value is hierarchically smaller than the EFT cut-off, assuming the EFT emerged from a unitary, causal and local UV completion. Future colliders may have the sensitivity to infer such a pattern of coefficients for a little hierarchy with an EFT cut-off up to O(10) TeV.

Topic: Theory and Pheno seminars

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

Meeting ID: 857 318 5271

Seminario di Fisica Teorica (Dr. Alessandro Georgoudis, Queen Mary)

In this talk I will present the S-matrix bootstrap program and its application to the study of 2d gapped and UV complete QFTs. In our work we extend the known results from pure S-matrix bootstrap by including into the set-up form factors and spectral functions of the stress energy tensor and conserved currents. I will explain how this extended set-up works and show how the associated sum rules allow us to put bounds on quantities like the central charge of the underlying conformal theories in the UV. Based on work with L. Córdova, M. Correia and A. Vuignier.

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-

The Bekenstein-Hawking entropy of supersymmetric and extremal (BPS) black holes has a precise statistical interpretation in the context of AdS/CFT duality. For non-BPS anti-de Sitter (AdS) black holes in dimensions larger than three, such a precise statistical interpretation has not been found yet. After reviewing the microscopic interpretation of the Bekenstein-Hawking entropy for large BPS black holes in five dimensional AdS, and time permitting, I will explain how some perturbative corrections, deviating from supersymmetry and extremality, can be computed in four-dimensional maximally supersymmetric SU(N) Yang Mills theory.

Topic: Theory and Pheno seminars

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

Meeting ID: 857 318 5271

Diffuse supernova neutrino background (DSNB), which is an integrated flux of neutrinos from all past core-collapse supernovae (CCSNe), are eagerly studied in the worldwide experiment because the detection of DNSB flux makes investigation about the star formation history as well as the neutrino emission from CCSNe.

Since 2020, Super-Kamiokande (SK) detector has been updated by loading gadolinium (Gd) as a new experimental phase, “SK-Gd”. In the SK-Gd experiment, neutrons can be efficiently identified due to high cross-section and high energy gamma-ray emission of thermal neutron capture on Gd. This enables to search low-energy electron antineutrinos such as a signal of DSNB via inverse-beta decay.

Until July 2022, the observation was operated with the 0.01% Gd mass concentration, termed as SK-VI. The neutron capture fraction on Gd is about 50% at that time. In this period, we operated neutron source calibration and obtained characteristics about the neutron identification in SK-Gd detector.

Using the whole period of SK-VI, we searched for astrophysical electron antineutrinos with the energy of O(10) MeV in SK-Gd with a 22.5×552 kton·day exposure at 0.01% Gd mass concentration for a first time in SK-Gd experiment.

This seminar provides the result of the search and prospects for future observation.

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