Effective Field theory opens up a new programme of searching for New Physics in the absence of evidence for any new light particles. I will discuss recent progress in theoretical computations for Effective Field Theory and present results of global effective theory interpretations of LHC measurements.
Latest advances on the formulation of a grand covariant quantum field theory that includes fermions will be presented.
The LHC experiments are designed to discover hypothetical particles with prompt decays. In parallel, meta-stable particles are constrained by cosmological observations. Between these two extremes, there is a gap with particles with moderate lifetimes, connecting hidden sectors and the Standard Model through feeble interactions in "portal" models of dark matter, neutrino masses and other...
I will review briefly how inflation is expected to generate a stochastic background of primordial gravitational waves (GWs). Then, I will discuss how such GWs can be enhanced by a stiff period following inflation, enough to be observable. I will present examples of this in the contact of hybrid inflation with alpha-attractors, or a period of hyper-kination in Palatini gravity.
Axions can be considered as good dark matter candidates. The detection of such light particles an be achieved by observing axion induced atomic excitations. The target is in a magnetic field so that the m-degeneracy is removed the energy levels can be suitably adjusted. Since the axion is absorbed by the atom the cross section exhibits resonance behavior. Using an axion-electron coupling...
In recent years we have been witnesses of the blooming of Gravitational Wave Astronomy. In the near future, with the more advanced, as well as the space-based detectors coming online, it is expected to detect events originating from compact binary objects at much higher rates. One of the future data analysis challenges, is performing robust statistical analyses in the presence of detector...
The REINFORCE EU project engages and supports citizens to cooperate with researchers and contribute to the development of new knowledge for science and society. REINFORCE offers four “discovery demonstrators” in different areas of physics. The infrastructure of all demonstrators is based on Zooniverse, the most popular citizen-science platform. The demonstrator titled “Search for new particles...
According to the current experimental data, the Higgs vacuum appears to be metastable due to the development of a second lower ground state in its potential. Consequently, vacuum decay would induce the nucleation of true vacuum bubbles with catastrophic consequences for our Universe and therefore we are motivated to study possible stabilising mechanisms in the early universe. In our latest...
Astroneu is an array for extensive air shower detection which is developed and operated in the Hellenic Open University campus near the city of Patras, Greece. In the first stage of operation (Astroneu I) it consisted of 9 scintillators detectors and 6 antennas, which were arranged in 3 stations. The Astroneu array is entering the next phase of operation, where 48 particle detectors and 16 RF...
Chern-Simons gravity with axions is revisited from the point of view of studying Kerr-like black hole solutions which take into account the back reaction of the axion field onto the spacetime geometry. We extend previous results by giving analytic expressions for slowly rotating black holes, which formally include an all order expansion in the pertinent coupling constant. We investigate...
Vector Boson Scattering (VBS) processes provide a great source of information on the structure of the Quartic Gauge Boson Couplings (QGCs). The Standard Model allows self interactions of the charged vector gauge bosons, although vertices with neutral-only bosons are forbidden. We use Monte Carlo samples containing VBS events with two Z-bosons in association with two jets, and we present...
Vector Boson Scattering in the WZ fully leptonic channel is being studied in ATLAS with the full Run 2 data of 139 fb-1. The importance of the channel for indirect New Physics searches beyond the Standard Model will be presented, and the procedure for an Effective Field Theory interpretation of the existence of quartic gauge couplings will be shown. Limits on anomalous couplings related to...
We examine how large the effects in $b\to s\ell^+\ell^-$ transitions in the MSSM with a general flavour structure can be. After carefully analyzing all potentially important supersymmetric contributions, we find that the largest effects arise in case of a light wino, a light smuon and muon sneutrino, a relatively light left stop, maximal mixing among left-handed down-squarks of the $2^{\rm...
This study presents an analysis of the ZZ->2l2v interaction using the full Run2 data of 139 fb-1 collected by the ATLAS detector at the LHC. The analysis includes a background estimation using a simultaneous fit method and a measurement of the cross section of the inclusive ZZ production, as well as in association with two jets, both differentially and inclusively. The ZZ->2l2v process is an...
The μΝet project is an extended educational program aiming for the deployment and operation of an extensive school network of educational Cosmic Ray telescopes throughout Greece. In the first year of operation (school term 2022-2023) 20 Cosmic Ray telescopes were installed in the region of Peloponnese, while more than 50 schools and 500 students from all over Greece attended by distance the...
In the general framework of Metric-Affine theories of gravity, where the metric and the connection are independent variables, we consider actions quadratic in the Ricci scalar curvature and the Holst invariant (the contraction of the Riemann curvature with the Levi-Civita antisymmetric tensor) coupled non-minimally to a scalar field. We study the profile of the equivalent effective metric...
I discuss the possibility that torsion in the early Universe, which is a feature of several cosmological models, also in the realm of string theory, can provide dark energy which is sufficient to lead to inflation, but also to matter-antimatter asymmetry in the post inflationary Universe, through the axion-like degrees of freedom associated with the torsion. Specifically, I discuss how such...
Application Specific Integrated Circuits are vital for the LHC experiments and have involved some of the biggest technology innovations applied in the LHC detectors. Using the history of some of the principal ASICs used by the CMS experiment at the LHC as a reference point, ASIC developments for the first LHC generation will be discussed, commenting on the challenges and risks and how they...
The ATLAS collaboration at LHC has endorsed the resistive Micromegas technology, along with the small-strip Thin Gap Chambers (sTGC), for the high luminosity upgrade of the first muon station in the high-rapidity region, the so called New Small Wheel (NSW) project. After the R&D, the prototyping phase, the first series production Micromegas quadruplets have been constructed and the...
From the perspective of Particle Physics and Field Theory, Dark Energy is a low energy phenomenon. Thus, we expect that field theory in curved space time should be sufficient to understand the physics of Dark Energy and its observational consequences. However, in the context of the Standard Model of Particle Physics obtaining fields with sufficiently low masses that can both be protected...
The classical and quantum properties of systems maybe drastically affected by imposing constraints in their phase space. Desirable properties such as unitarity and renormalizability may not be retained. In this general context we consider a specific model which by construction is also classically integrable. After imposing a constraint we show that at tree level integrability is preserved ...
We derive the quantum energy-momentum tensor and the corresponding quantum equation of state for gauge field theory using the effective Lagrangian approach. The energy-momentum tensor has a term proportional to the space-time metric and provides a finite non-diverging contribution to the effective cosmological term. This allows to investigate the influence of the gauge field theory vacuum...
An update concerning the Network Activities during the last year will be given with a focus on the Athens Group.
We summarize the famous tensions between various observational datasets and theoretical predictions of the Standard Model of Cosmology, such as the H0 and S8 tensions, that could be a sign that we are approaching New Physics. Then we provide possible solutions, arising from modifications /extensions of the standard lore.
This talk will address the challenges and necessary technological advances for accelerator and detector optimization, further R&D work on critical technologies within the ILC International Technology Network (ITN), and discuss plans on power, energy and sustainability for future Linear Collider facilities.
In this talk we will discuss models which allows the simultaneous generation of the baryon asymmetry of the Universe along with its dark matter content. We employ the out-of-equilibrium decays of heavy bath states into a feebly coupled dark matter particle and Standard Model charged fermions. These decays lead to dark matter production via the freeze-in mechanism and, assuming that they...
Silicon detectors are used in Nuclear and Particle Physics since the 60-ies. However, the real break-through came in the early 80-ies when micrometer-position resolution for charged particle was achieved and their superior performance for tracking down short-lived particles in the Particle Physics experiments demonstrated.
This presentation outlines the historical evolution from strip...
I discuss the entanglement entropy resulting from tracing out local degrees of freedom of quantum harmonic systems, which include free scalar field theory as a continuum limit. It is known that the entanglement entropy of such a system in its ground state is dominated by an area law term. This peculiar feature resembles the famous property of black hole entropy. I summarize the calculation of...
CAST is astroparticle physics experiment of CERN since 1999, searching mainly for axions. Without having observed as yet this theoretically postulated particle, CAST have further narrowed the phase space for the axion. Today, it is reasonable to say that the rest mass of this tiny particle is probably in the sub-meV range. Following a suggestion (with other 8 colleagues from 7 afiliations)...
The upcoming High Luminosity upgrade of the LHC will provide us with experimental data of unprecedented precision. Making sense of the data and exploiting the machine’s full potential will require theoretical predictions of equally high precision. In recent years, the theoretical particle physics community has made a tremendous effort to meet the challenge of performing notoriously difficult...
Supersymmetry (SUSY) remains one of the most appealing theories beyond the standard model (BSM) of elementary particles, due to its completeness, rich phenomenology, and ability to provide answers to fundamental open questions of modern particle physics and cosmology. The LHC Run II sample of pp collisions at 13 TeV center-of-mass energy collected with the CMS detector is a statistically...
Cosmological simulations for cold dark matter (DM) suggest that a large number of streams might exist in our Galaxy. The current work includes gravitational focusing (GF) effects on streaming DM constituents by the Sun and the Earth as they approach the Earth bound detectors. For streaming DM, the GF gives rise to spatiotemporal flux enhancements of orders of magnitude above the nominal DM...
We propose a modification of no-scale supergravity models which incorporates sgoldstino stabilization and supersymmetry (SUSY) breaking with a tunable cosmological constant by introducing a Kahler potential which yields a kinetic pole of order one. The resulting scalar potential may develop an inflection point close to which an inflationary period can be realized for subplanckian field values...
We will study the effects of an anomalous Z' boson on the anomalous magnetic moment of the muon (g-2), and especially the impact of its axial coupling. We mainly evaluate the negative contribution to (g-2) of such couplings at one-loop and look at the anomalous couplings generated at two loops. We find areas of the parameter space, where the anomalous contribution becomes comparable and even...
A measurement is presented of the ratio observable $R_{\Delta\phi}$, which is related in a novel way to the azimuthal correlations among jets. It is defined as the fraction of the number of neighboring jets exceeding a minimal transverse momentum of 100 GeV within a 3-jet topology enforced through the allowed azimuthal angular separation of $2\pi/3<\Delta\phi<7\pi/8$ with respect to the...
We study Carrollian hydrodynamics on arbitrary backgrounds by employing two distinct but complementary paths. The first one is Carrollian diffeomorphism invariance while the second one consists in analyzing the relativistic fluid equations at small speed of light. The results of the method agree, but the second approach is superior as it effortlessly captures more elaborate situations with...
The Barrel Muon Trigger (BMT) is a part of the upgraded CMS Level-1 Trigger and is the subsystem responsible for searching and reconstructing Muons crossing the barrel region of the detector at Phase-2. Muons crossing the Barrel Muon detector are measured by Drift Tubes and Resistive Plate Chambers. Hits are transmitted to the back end processors via optical links. BMT Layer-1 then uses the...
An ATCA processor was designed to instrument the first layer of the CMS Barrel Muon Trigger. The processor receives and processes DT and RPC data and produces muon track segments. Furthermore, it provides readout for the DT detectors. The ATCA processor is based on a Xilinx XCVU13P FPGA, it receives data via 10 Gbps optical links and transmits track segments via 25 Gbps optical links. The...
We analyse in all generality beyond Horndeski theories of shift symmetry in a static and spherically symmetric spacetime. By introducing four auxiliary functions, we write the field equations in a particularly compact form. We show that assuming additionally parity symmetry renders the system directly integrable giving multiple families of black-hole solutions. These have typically an...
A measurement of the dijet production cross section is reported based on an integrated luminosity of $36.3 fb^{-1}$ of proton-proton collision data collected in 2016 at $\sqrt{s} = 13$ TeV by the CMS detector at the CERN LHC. Jets are reconstructed with the anti-$k_T$ algorithm for distance parameters of $R = 0.4$ and $R = 0.8$ and differential cross sections are measured as a function of the...
A measurement of inclusive differential multijet cross sections and ratios is presented. The analysis is based on data from proton-proton collisions collected by the CMS experiment at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 59.8 $fb^{-1}$. The observables $R_{mn}$ are calculated from the corresponding differential multijet cross sections with different...
Neutron stars are some of the most fascinating stellar objects in the universe, offering unique opportunities to study fundamental physics at supra-nuclear densities. However, their internal structure remains poorly known due to the uncertainties in the equation of state (EoS). In recent years, a lot of work has revealed the existence of universal relations between various observable...
