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First measurement of the energy and Mandelstam-t dependence of incoherent J/ψ photonuclear production with ALICE
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Quantum chromodynamics predicts that at sufficiently high energies the gluon density inside hadrons enters a regime, known as gluon saturation, where gluon splitting and recombination reach a dynamic equilibrium. Diffractive photoproduction of J/ψ mesons is a particularly sensitive probe of this phe- nomenon, since it directly couples to the gluon distribution of the nucleus. With its unique coverage of photon–nucleon center-of-mass energies from about 20 to 800 GeV, the ALICE detector can study the energy dependence of J/ψ production across three orders of magnitude in Bjorken-x.
In this talk, I will present the latest ALICE measurements of the energy dependence of incoher- ent photonuclear J/ψ production in Pb–Pb ultra-peripheral collisions at √sNN = 5.02 TeV, analyzed in three Mandelstam-t intervals. While low-|t| production reflects the average gluon density in nu- clei, higher-|t| values probe gluon fluctuations at smaller spatial scales. The observed suppression of the cross-section growth with energy at large |t| relative to low |t| provides new evidence of gluon saturation–like dynamics, offering unprecedented constraints on models of QCD in the high-energy limit.
Refreshments will be served at 10h30
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Top Quark Cross Section and Mass Measurements at ATLAS and CMS
No full textThe top-quark mass is one of the key fundamental parameters of the Standard Model that must be determined experimentally. Its value has an important effect on many precision measurements and tests of the Standard Model. The Tevatron and LHC experiments have developed an extensive program to determine the top quark mass using a variety of methods. In this contribution, the top quark mass measurements by the ATLAS and CMS experiments are reviewed. These include measurements in two broad categories, the direct measurements, where the mass is determined from a comparison with Monte Carlo templates, and determinations that compare differential cross-section measurements to first-principle calculations. The exceptionally large dataset collected by the ATLAS detector at the highest proton-proton collision energies provided by the LHC enables precision testing of theoretical predictions using an extensive sample of top quark events. Measurements of the inclusive top quark production rates at the LHC have reached a precision of several percent and test advanced Next-to-Next-to-Leading Order predictions in QCD. Differential measurements in several observables are important to test SM predictions and improve Monte Carlo generator predictions. Recent measurements include total and differential top quark cross sections, as well as detailed studies of top quark production at various center-of-mass energies. This contribution presents the latest highlights from the ATLAS top quark physics program, including key measurements from Run II, and new results using Run III data
Towards mono-energetic virtual beam cross-section measurements: A feasibility study of -Ar interaction analysis with DUNE-PRISM
No full textNeutrino-nucleus cross-section measurements are critical for future neutrino oscillation analyses. However, our models to describe them require further refinement, and a deeper understanding of the underlying physics is essential for future neutrino oscillation experiments to realize their ambitious physics goals. Current neutrino cross-section measurements provide clear deficiencies in neutrino interaction modeling, but almost all are reported averaged over broad neutrino fluxes, rendering their interpretation challenging. Using the DUNE-PRISM concept (Deep Underground Neutrino Experiment Precision Reaction Independent Spectrum Measurement) -- a movable near detector that samples multiple off-axis positions -- neutrino interaction measurements can be used to construct narrow virtual fluxes (less than 100 MeV wide). These fluxes can be used to extract charged-current neutrino-nucleus cross sections as functions of outgoing lepton kinematics within specific neutrino energy ranges. Based on a dedicated simulation with realistic event statistics and flux-related systematic uncertainties, but assuming an almost-perfect detector, we run a feasibility study demonstrating how DUNE-PRISM data can be used to measure muon neutrino charged-current integrated and differential cross sections over narrow fluxes. We find that this approach enables a model independent reconstruction of powerful observables, including energy transfer, typically accessible only in electron scattering measurements, but that large exposures may be required for differential cross-section measurements with few-% statistical uncertainties
RF Measurement and Tuning of the Linac4 Spare RFQ
No full textThe first radio-frequency (RF) accelerating structure in Linac4 is a 352.2 MHz, three-metre-long radio-frequency quadrupole (RFQ) that bunches and accelerates the 45 keV H- beam from the ion source to an energy of 3 MeV. As the RFQ constitutes a single point of failure (SPOF) in Linac4, an almost identical spare has been manufactured. The spare cavity is comprised of three sections, each one metre in length, and features 32 cylindrical tuners. This document describes the low-power RF measurement results and the procedures used to tune the frequency, the electromagnetic field profile, and the power coupler
Combination of searches for nonresonant Higgs boson pair production in proton-proton collisions at 13 TeV
No full textThis paper presents a combination of searches for the nonresonant production of Higgs boson pairs (HH) in proton-proton collisions at a centre-of-mass energy of 13 TeV. The data set was collected by the CMS experiment at the LHC from 2016 to 2018 and corresponds to a total integrated luminosity of 138 fb. The observed (expected) upper limit on the inclusive HH production cross section relative to the standard model (SM) prediction is found to be 3.5 (2.5). Assuming all other Higgs boson couplings are equal to their SM values, the Higgs boson trilinear self-coupling modifier is constrained in the range 1.35 6.37 at 95% confidence level. Similarly, for the coupling modifier , which governs the interaction between two vector bosons and two Higgs bosons, we have excluded 0 at more than 5 standard deviations for all values of . At 95% confidence level assuming other couplings are equal to their SM values, is constrained in the range 0.64 1.40. This work also studies HH production in several new physics scenarios, using the Higgs effective field theory (HEFT) framework. The HEFT framework is further exploited to study various ultraviolet complete models with an extended Higgs sector and set constraints on specific parameters. An extrapolation of the results to the integrated luminosity expected after the high-luminosity upgrade of the LHC is reported as well.This paper presents a combination of searches for the nonresonant production of Higgs boson pairs (HH) in proton-proton collisions at a centre-of-mass energy of 13 TeV. The data set was collected by the CMS experiment at the LHC from 2016 to 2018 and corresponds to a total integrated luminosity of 138 fb. The observed (expected) upper limit on the inclusive HH production cross section relative to the standard model (SM) prediction is found to be 3.5 (2.5). Assuming all other Higgs boson couplings are equal to their SM values, the Higgs boson trilinear self-coupling modifier is constrained in the range 1.35 6.37 at 95% confidence level. Similarly, for the coupling modifier , which governs the interaction between two vector bosons and two Higgs bosons, we have excluded = 0 at more than 5 standard deviations for all values of . At 95% confidence level assuming other couplings are equal to their SM values, is constrained in the range 0.64 1.40. This work also studies HH production in several new physics scenarios, using the Higgs effective field theory (HEFT) framework. The HEFT framework is further exploited to study various ultraviolet complete models with an extended Higgs sector and set constraints on specific parameters. An extrapolation of the results to the integrated luminosity expected after the high-luminosity upgrade of the LHC is reported as well
Her Excellency Dr Regina Valutyte Vice-Minister of Science and Studies Ministry of Education, Science and Sport Republic of Lithuania
No full text- Signature of the Memorandums of Understanding for the Future Circular Collider (FCC) Feasibility Study between Vilnius University (VU) represented by R. Petrauskas, Kaunas University of Technology (KTU) represented by E. Valatka, Lithuanian University of Health Sciences (LSMU) represented by R. Benetis and CERN, represented by M. Lamon