Low-x QCD with CMS at the LHC

The physics of gluon saturation and non-linear evolution at small values of parton momentum fraction x in the proton and nucleus is discussed in the context of experimental results at HERA and RHIC. The rich physics potential of low-x QCD studies at the LHC is discussed and some measurements in pp, pA and AA collisions accessible with the Compact Muon Solenoid (CMS) experiment are presented.Comment: Extended clarifications to Eq. (6). A couple of typos corrected. To appear in EPJ

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

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.

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

CMS physics highlights in the LHC Run 1

The main physics results obtained by the CMS experiment during the first three years of operation of the CERN Large Hadron Collider (2010--2013, aka. Run 1) are summarized. The advances in our understanding of the fundamental particles and their interactions are succinctly reviewed under the following physics topics: (i) Quantum Chromodynamics, (ii) Quark Gluon Plasma, (iii) Electroweak interaction, (iv) Top quark, (v) Higgs boson, (vi) Flavour, (vii) Supersymmetry, (viii) Dark Matter, and (ix) other searches of physics beyond the Standard Model.Comment: 14 pages, 9 figures. Proceedings Bormio'2015. PoS, to appear. Typo correcte

High p_T identified particles in PHENIX: data vs. theory

Two of the most interesting experimental results of heavy-ion reactions at RHIC collider energies are in the hard scattering sector where central Au+Au data show a very different behaviour compared to p+p and peripheral Au+Au collisions. The so-called ``high p_T pi^0 suppression'' and the ``anomalous'' baryon/meson ratio observed by PHENIX in central Au+Au collisions at sqrt(s_{NN}) = 200 GeV are reviewed and compared to various theoretical calculations based on different strongly interacting medium scenarios.Comment: To appear in the proceedings of 19th Winter Workshop on Nuclear Dynamics, Breckenridge, Colorado, US, March 8-15, 200

Improved strong coupling determinations from hadronic decays of electroweak bosons at N3^3LO accuracy

We present two new extractions of the QCD coupling constant at the Z pole, $\alpha_S(m_Z)$, from detailed comparisons of inclusive W and Z hadronic decays data to state-of-the-art perturbative Quantum Chromodynamics calculations at next-to-next-to-next-to-leading order (N$^{3}$LO) accuracy, incorporating the latest experimental and theoretical developments. In the W boson case, the total width computed at N$^{3}$LO is used for the first time in the extraction. For the Z boson pseudo-observables, the N$^{3}$LO results are complemented with the full two- and partial three-loop electroweak corrections recently made available, and the experimental values are updated to account for newly estimated LEP luminosity biases. A combined reanalysis of the Z boson data yields $\alpha_S(m_Z) = 0.1203 \pm 0.0028$, with a 2.3\% uncertainty reduced by about 7\% compared to the previous state-of-the-art. From the combined W boson data, a value of $\alpha_S(m_Z) = 0.101 \pm 0.027$ is extracted, with still large experimental uncertainties but also reduced compared to previous works. The levels of theoretical and parametric precision required in the context of QCD coupling determinations with permil uncertainties from high-statistics W and Z boson samples expected at future $e^+e^-$ colliders such as the FCC-ee, are discussed in detail.Comment: 18 pages, 5 figure