High-density QCD with CMS at the LHC

The capabilities of the CMS experiment to explore the rich heavy-ion physics programme offered by the CERN Large Hadron Collider (LHC) are summarised. Various representative measurements in Pb-Pb collisions at sqrt(s) = 5.5 TeV are covered. These include "bulk" observables (charged hadron multiplicity, low-pT inclusive hadron spectra and elliptic flow) which provide information on the collective properties of the system; as well as perturbative processes (high-pT hadrons, jets, gamma-jet and quarkonium production) which yield "tomographic" information of the densest phases of the reaction.Comment: 8 pages, 7 figs. Proceeds plenary talk Quark-Matter'08, Jaipur, India. To appear in J. Phys.

High-energy heavy-ions physics: from RHIC to LHC

A selection of experimental results in high-energy nucleus-nucleus collisions after five years of operation of the Relativistic Heavy-Ion Collider (RHIC) is presented. Emphasis is put on measurements that provide direct information on fundamental properties of high-density QCD matter. The new experimental opportunities accessible at LHC are introduced, in particular those that may help clarify some of the current open issues at RHIC.Comment: A few misprints corrected. Matches version to appear in NP

Impact of LHC Run-1 on particle astrophysics

An overview of the impact of the first three years of LHC operation on two of the most important open questions in astroparticle physics is presented. Measurements in proton-proton collisions at the energy frontier that provide valuable information on the identity of the highest-energy particles in the cosmos as well as new constraints on the nature of dark matter, are summarized.Comment: 7 pages, 8 figures. Proceedings invited plenary talk at "2nd Intl. Conf. on New Frontiers in Physics" (ICNFP 2013) in Kolymbari, Crete. To appear in Eur.Phys.J.Con

αs\alpha_s review (2016)

The current world-average of the strong coupling at the Z pole mass, $\alpha_s(m^2_{Z}) = 0.1181 \pm 0.0013$, is obtained from a comparison of perturbative QCD calculations computed, at least, at next-to-next-to-leading-order accuracy, to a set of 6 groups of experimental observables: (i) lattice QCD "data", (ii) $\tau$ hadronic decays, (iii) proton structure functions, (iv) event shapes and jet rates in $e^+e^-$ collisions, (v) Z boson hadronic decays, and (vi) top-quark cross sections in p-p collisions. In addition, at least 8 other $\alpha_s$ extractions, usually with a lower level of theoretical and/or experimental precision today, have been proposed: pion, $\Upsilon$, W hadronic decays; soft and hard fragmentation functions; jets cross sections in pp, e-p and $\gamma$-p collisions; and photon F$_2$ structure function in $\gamma\,\gamma$ collisions. These 14 $\alpha_s$ determinations are reviewed, and the perspectives of reduction of their present uncertainties are discussed.Comment: 4 pages, 2 figures. Minor changes. Version submitted to Proceedings Moriond QCD 201

Physics case of FCC-ee

The physics case for electron-positron beams at the Future Circular Collider (FCC-ee) is succinctly summarized. The FCC-ee core program involves $e^+e^-$ collisions at $\sqrt{s}$ = 90, 160, 240, and 350 GeV with multi-ab$^{-1}$ integrated luminosities, yielding about 10$^{12}$ Z bosons, 10$^{8}$ W$^+$W$^-$ pairs, 10$^{6}$ Higgs bosons and 4$\cdot$10$^{5}$ $t\bar{t}$ pairs per year. The huge luminosities combined with $\cal{100}$ keV knowledge of the c.m. energy will allow for Standard Model studies at unrivaled precision. Indirect constraints on new physics can thereby be placed up to scales $\Lambda_{_{\rm NP}} \approx$ 7 and 100 TeV for particles coupling respectively to the Higgs and electroweak bosons.Comment: 8 pages, 6 figures. Proceedings LFC15: Physics Prospects for Linear and Other Future Colliders, ECT*, Trento, Oct. 201

Physics at the FCC-ee

The physics program accessible in $e^+e^-$ collisions at the Future Circular Collider (FCC-ee) is summarized. The FCC-ee aims at collecting multi-ab$^{-1}$ integrated luminosities in $e^+e^-$ at $\sqrt{s}$ = 90, 160, 240, and 350 GeV, yielding 10$^{12}$ Z bosons, 10$^{8}$ W$^+$W$^-$ pairs, 10$^{6}$ Higgs bosons and $4\cdot 10^{5}$ top-quark pairs per year. Such huge data samples combined with a $\cal{O}(100 \rm keV)$ c.m. energy uncertainty will allow for Standard Model measurements with unparalleled precision and searches for new physics in regions not probed so far. The FCC-ee will be able to (i) indirectly discover new particles coupling to the Higgs and electroweak bosons up to scales $\Lambda \approx$ 7 and 100 TeV; (ii) perform competitive SUSY tests at the loop level in regions beyond the LHC reach; and (iii) achieve the best potential in direct collider searches for dark matter and sterile neutrinos with masses below 60 GeV.Comment: 8 pages, 8 figures. Proceedings 17th Lomonosov conference on Elementary Particle Physics, Moscow, Aug. 2015. World Scientific, to appear. arXiv admin note: text overlap with arXiv:1601.06640

Higgs and Beyond the Standard Model physics with the FP420 detector at the LHC

The physics case of the FP420 R&D project aiming at the installation of proton detectors in the LHC tunnel at 420 m from the ATLAS and CMS interaction points, is presented. The motivations of the measurements accessible with FP420 -- exclusive Higgs production (pp --> p H p) and photon-induced processes (pp --> p gamma p --> p X p, pp --> p gamma gamma p --> p X p, where X is sensitive to new physics) -- are outlined.Comment: Proceedings Moriond-QCD 2009. 5 pages, 3 fig

Higgs physics at the Future Circular Collider

The unique Higgs physics opportunities accessible at the CERN Future Circular Collider (FCC) in electron-positron ($\sqrt{s}$ = 125, 240, 350 GeV) and proton-proton ($\sqrt{s}$ = 100 TeV) collisions, are succinctly summarized. Thanks to the large c.m. energies and enormous luminosities (plus clean experimental conditions in the $e^+e^-$ case), many open fundamental aspects of the Higgs sector of the Standard Model (SM) can be experimentally studied: (i) Measurement of the Higgs Yukawa couplings to the lightest fermions: u,d,s quarks (via rare exclusive $H\to(\rho,\omega,\phi)+\gamma$ decays); and e$^\pm$ (via resonant s-channel $e^+e^-\to H$ production); as well as neutrinos (within low-scale seesaw mass generation scenarios); (ii) Measurement of the Higgs potential (triple $\lambda_3$, and quartic $\lambda_4$ self-couplings), via double and triple Higgs boson production in pp collisions at 100 TeV; (iii) Searches for new physics coupled to the scalar SM sector at scales $\Lambda>$ 6 TeV, thanks to measurements of the Higgs boson couplings with subpercent uncertainties in $e^+e^-\to H\,Z$; and (iv) Searches for dark matter in Higgs-portal interactions, via high-precision measurements of on-shell and off-shell Higgs boson invisible decays. All these measurements are beyond the reach of pp collisions at the Large Hadron Collider. New higher-energy $e^+e^-$ and pp colliders such as FCC are thus required to complete our understanding of the full set of SM Higgs parameters, as well as to search for new scalar-coupled physics in the multi-TeV regime.Comment: 8 pages, 5 figures. Proceeds ICHEP'16, Chicago (USA