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production in pp collisions at TeV
No full textThe first measurement of production at the LHC is presented. The measurement is performed at midrapidity in both minimum-bias and high-multiplicity pp collisions at TeV. The is reconstructed via its weak-decay topology in the decay channel with . In a novel approach, the neutral pion is reconstructed by combining photons that convert in the detector material with photons measured in the calorimeters. The transverse-momentum () distributions of the and its rapidity densities / in both event classes are reported. The spectrum in minimum-bias collisions is compared to QCD-inspired event generators. The ratio of to previously measured baryons is in good agreement with calculations from the Statistical Hadronization Model. The high efficiency and purity of the novel reconstruction method for presented here will enable future studies of the interaction of with protons in the context of femtoscopic measurements, which could be crucial for understanding the equation of state of neutron stars.The measurement of production in pp collisions at TeV is presented. The measurement is performed at midrapidity in both minimum-bias and high-multiplicity pp collisions at TeV. The is reconstructed via its weak-decay topology in the decay channel with . In a novel approach, the neutral pion is reconstructed by combining photons that convert in the detector material with photons measured in the calorimeters. The transverse-momentum () distributions of the and its rapidity densities ddy in both event classes are reported. The spectrum in minimum-bias collisions is compared to QCD-inspired event generators. The ratio of to previously measured baryons is in good agreement with calculations from the Statistical Hadronization Model. The high efficiency and purity of the novel reconstruction method for presented here will enable future studies of the interaction of with protons in the context of femtoscopic measurements, which could be crucial for understanding the equation of state of neutron stars
Exploring the Hilbert Space of Quantum Field Theory with Hamiltonian Truncation
No full textThis talk will give a personal view of Hamiltonian truncation for quantum field theory. This is a variational approximation of quantum field theory formulated directly in the continuum, in which the Hamiltonian of the theory is numerically diagonalized on a large but finite subspace of states. This method can preserve symmetries that are broken by the lattice, for example chiral symmetries and supersymmetry, and therefore can be applied to theories that are otherwise inaccessible to numerical approximation. The truncated theory is a non-local effective theory, but with a systematic power counting that allows for an "improvement" program similar to the one used on the lattice. I will discuss some of the promise and challenges of Hamiltonian truncation, including the application to chiral gauge theories.
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Search for charged Higgs bosons decaying into a top and a bottom quark in proton-proton collisions at sqrt{s} = 13 TeV
No full textA search is presented for charged Higgs bosons () in proton-proton () collision events via the processes with decays. The analysis is based on the data collected at a center-of-mass energy of 13 TeV with the CMS detector at the LHC, corresponding to an integrated luminosity of 138 . Charged Higgs bosons in the 200 GeV to 1 TeV mass range are targeted in the search. The results are interpreted in the framework of the generalized two-Higgs-doublet model (g2HDM) assuming the real components of the extra Yukawa couplings and range up to unity. No significant excess above the standard model prediction is observed. Stringent upper limits at confidence level are derived on the product of the cross section and branching ratio , where , for boson masses up to TeV for depending on the and assumption. The results represent the first search for charged Higgs bosons based on the g2HDM at any collider and complement the existing results on additional neutral Higgs bosons
Precision luminosity measurement in proton-proton collisions at sqrt{s} = 13 TeV with the CMS detector
No full textThe measurement of the integrated luminosity recorded by the CMS detector at the LHC in proton-proton collisions at in 2017 and 2018 is reported. The absolute luminosity calibration is obtained with the van der Meer (vdM) method through beam-separation scans that were performed in special accelerator conditions. The extrapolation to regular data-taking conditions relies on detector-specific measurements. Multiple independently calibrated luminosity detectors (luminometers) are employed to derive the final integrated luminosity. A relative precision of and is achieved for the 2017 and 2018 data sets, respectively. Dominant uncertainties are the luminometer nonlinearity and the assumption of transverse factorizability in the vdM method. The consistency of the measurements for 2016, 2017, and 2018 is evaluated using Z boson rates. When combined with the 2015--2016 data sets at the same center-of-mass energy, the relative precision of the total integrated luminosity is , representing the most precise luminosity measurement ever achieved at bunched-beam hadron colliders. This is possible due to improved vdM methodology and the combination of results by independent luminometers
Searches for Higgs boson pair production in the ATLAS experiment
No full textIn the Standard Model, the ground state of the Higgs field is not found at zero but instead corresponds to one of the degenerate solutions minimising the Higgs potential. In turn, this spontaneous electroweak symmetry breaking provides a mechanism for the mass generation of nearly all fundamental particles. The Standard Model makes a definite prediction for the Higgs self-coupling and thereby the shape of the Higgs potential. Experimentally, both can be probed through the production of Higgs boson pairs (HH), a rare process that presently receives a lot of attention at the LHC. In this talk, the latest non resonant HH searches in ATLAS, as well as their statistical combination, are reported, with emphasis on the results obtained with the full LHC Run 2 dataset at 13 TeV and a partial Run 3 dataset at 13.6 TeV. Results are interpreted both in terms of sensitivity to the Standard Model and as limits on the Higgs self-coupling and Wilson coefficients in Effective Field Theories
Microdosimetry of Very-High-Energy Heavy Ion Beams for Electronics Testing Using Silicon-on-Insulator Detectors
No full textThis article explores the use of microdosimetry with
a silicon-on-insulator (SOI) detector for characterizing very-high-
energy (VHE) heavy ion beams used specifically for single event
effect (SEE) testing of electronics. The detector was deployed
at CERN’s heavy ion facility for radiation effects testing and
exposed to lead ion beams in the 100–1000 MeV per nucleon
kinetic energy range. The implications and possible benefits of
using microdosimetry for SEE testing purposes are discussed
Hadronic interaction at LHC: review for the LHCf and air shower related measurements
No full textFifteen years have past since the first beam collisions at the Large Hadron Collider (LHC) in CERN.Not only the discovery of the Higgs particle, the LHC made a significant contribution to the cosmic-ray community.Its designed collision energy =14TeV corresponds to the collision of a 10eV proton on a protonat the rest frame, which is the energy range handled by the air shower observations.The particle productions in the minimum-bias events and very-forward events have been extensively measured by thevarious dedicated detectors at the LHC, and they serve crucial tests for the hadronic interaction models used in the cosmic-ray air shower simulations. In addition, collisions realized at various are used to test the energy evolution of the hadronic interaction.In this paper, we will review the key measurements at the LHC relevant to the air shower simulations especially focusingon the forward measurements.We will start the review from a quick outlook of some important concepts used in the high-energy and collider physics
Search for heavy neutral leptons in decays of bosons produced in 13 TeV collisions using prompt signatures in the ATLAS detector
No full textThe existence of right-handed neutrinos with Majorana masses below the electroweak scale could help address the origins of neutrino masses, the matter-antimatter asymmetry, and dark matter. In this paper, leptonic decays of bosons from 140 fb of 13 TeV proton-proton collisions at the LHC, reconstructed in the ATLAS experiment, are used to search for heavy neutral leptons produced through their mixing with muon or electron neutrinos in a scenario with lepton number violation. The search is conducted using prompt leptonic decay signatures. The considered final states require two same-charge leptons or three leptons, while vetoing three-lepton same-flavour topologies. No significant excess over the expected Standard Model backgrounds is found, leading to constraints on the heavy neutral lepton's mixing with muon and electron neutrinos for heavy-neutral-lepton masses. The analysis excludes values above and values above in the full mass range of 8-65 GeV. The strongest constraints are placed on heavy-neutral-lepton masses in the range 15-30 GeV of and .The existence of right-handed neutrinos with Majorana masses below the electroweak scale could help address the origins of neutrino masses, the matter-antimatter asymmetry, and dark matter. In this paper, leptonic decays of W bosons from 140 fb of 13 TeV proton-proton collisions at the LHC, reconstructed in the ATLAS experiment, are used to search for heavy neutral leptons produced through their mixing with muon or electron neutrinos in a scenario with lepton number violation. The search is conducted using prompt leptonic decay signatures. The considered final states require two same-charge leptons or three leptons, while vetoing three-lepton same-flavour topologies. No significant excess over the expected Standard Model backgrounds is found, leading to constraints on the heavy neutral lepton's mixing with muon and electron neutrinos for heavy-neutral-lepton masses. The analysis excludes values above and values above in the full mass range of 8-65 GeV. The strongest constraints are placed on heavy-neutral-lepton masses in the range 15--30 GeV of and
Advancing gravitational wave predictions from cosmological first-order phase transitions
No full textIn this talk, I will investigate the formation of Primordial Black Holes as the result of the collapse of energy density fluctuations originating from supercooled first-order phase transitions. I will present the results of a simplified approach, where the energy density fluctuations are evolved within the limit of flat FRW Universe. I will show how energy density fluctuations modify the Gravitational Wave signals as the production of secondary Gravitational Waves is induced. Finally, we will discuss the full covariant formalism of cosmological perturbation and show how it impacts the production of Primordial Black Holes and Gravitational Waves