A clear evidence of inclusive diffraction observed by the CMS detector at the Large Hadron Collider in minimum bias events at $\sqrt{s}=$0.9 TeV, 2.36 TeV is presented. The observed diffractive signal is dominated by inclusive single-diffractive dissociation and can be identified by the presence of a Large Rapidity Gap that extends over the forward region of the CMS detector. A comparison of the data with Monte Carlo predictions provided by PYTHIA6 and PHOJET generators is given. In addition, first observation of the single-diffractive production of di-jets at $\sqrt{s}=$7 TeV is presented.
Recent CMS results on diffraction are presented. These include the measurements of the soft diffractive cross sections, of the forward rapidity gap cross section, of the diffractive dijet cross section, the measurement of a large rapidity gap in W and Z boson events and the measurement of the pseudorapidity distribution of charged particles in a single diffractive enhanced sample. This last measurement is the first common result of the CMS and TOTEM collaborations. Some prospects of common CMS-TOTEM data taking are also discussed.
In these proceedings we present CMS results on hard diffraction. Diffractive dijet production in pp collisions at $\sqrt{s}$=7 TeV is discussed. The cross section for dijet production is presented as a function of $\tildeξ$, representing the fractional momentum loss of the scattered proton in single-diffractive events. The observation of W and Z boson production in events with a large pseudo-rapidity gap is also presented.
We present measurements of soft single- and double-diffractive cross sections, as well as of forward rapidity gap cross sections at 7 TeV at the LHC, and compare the results to other measurements and to theoretical predictions implemented in various Monte Carlo simulations.
The observation of inclusive diffraction with the CMS detector at the LHC is presented for centre-of-mass energies \sqrt s = 0.9 TeV and 2.36 TeV. Diffractive events are selected by the presence of a Large Rapidity Gap in the forward region of the CMS detector and uncorrected data are compared with Monte Carlo simulations based on the event generators PYTHIA and PHOJET. The measurement of the forward energy flow, in the pseudorapidity region 3.15 < |η| < 4.9, is also presented at \sqrt s = 0.9 TeV, 2.36 TeV and 7 TeV. Uncorrected data are compared with Monte Carlo simulations based on PYTHIA.
Exclusive and diffractive physics measurements are important for the better understanding of the non-perturbative regime of QCD. Two recent results of the CMS experiment is presented in this paper. The total and differential cross sections of central exclusive $π^+π^-$ production are measured at 5.02 and 13 TeV in the $p_{\mathrm{T}}(π) > 0.2~$GeV/$c$ and $|η(π)| < 2.4$ kinematic region. The invariant mass distribution is fitted by the sum of a continuum and four interfering relativistic Breit-Wigner functions. In the second part of the paper the measurement of the single diffractive dijets is…
We report on the recent CMS measurements of soft hadron-hadron production, including the measurements of inclusive single- and double-diffractive cross sections, as well as the measurement of pseudorapidity distributions, and of the leading charged particle and leading jet cross sections. We present the cross sections for low-pT forward jets production, and production of dijets with large rapidity separation (central-forward, and forward-backward jets). Studies of double parton scattering using four-jet and W+2-jet events, and the cross sections for Drell-Yan with associated jet production are…
The forward physics program of the CMS experiment at the LHC spans a broad range of diverse physics topics including studies of low-x QCD and diffractive scattering, multi-parton interactions and underlying event structure, gamma-mediated processes and luminosity determination, Monte Carlo tuning and even MSSM Higgs discovery in central exclusive production. In this article, the forward detector instrumentation around the CMS interaction point is described and the prospects for diffractive and forward physics using the CMS forward detectors are summarized. In addition, first observation of for…
We report on a precision measurement of the effective weak mixing angle using the forward-backward asymmetry, $A_{FB}$, in Drell-Yan ($ee$ and $μμ$) events in pp collisions at $\sqrt{s}=8~\mathrm{TeV}$ at the CMS experiment at the Large Hadron Collider (LHC). The results are compared to other hadron collider measurements published by ATLAS, LHCb, CDF, D0 and Tevatron combination.
Measurements of hadron production in pp collisions by the ATLAS and CMS experiments are presented, including charged particle transverse momentum, pseudorapidity and event-by-event multiplicity distributions at sqrt(s) = 0.9, 2.36 and 7 TeV, for NSD and inelastic events. Diffraction is studied with either diffraction enriched or suppressed data samples. Total inelastic cross-section as well as gap cross-section measurements are shown. Measured spectra of identified strange hadrons, reconstructed based on their decay topology, are also discussed. Comparisons to several QCD Monte Carlo models an…
We discuss the observability of the lightest neutral Higgs boson in the constrained MSSM (CMSSM), with universal soft supersymmetry-breaking parameters, at hadron colliders such as the Tevatron and the LHC. We take account of the constraints on parameter space provided by LEP, the measured rate of b to s gamma decay, the cosmological relic density Omega h^2, and the recent measurement of g_mu - 2. We normalize products of the expected CMSSM Higgs production cross sections and decay branching ratios (sigma B)_CMSSM relative to those expected for a Standard Model Higgs boson of the same mass. In…
We present results from a measurement of double diffraction dissociation in $\bar pp$ collisions at the Fermilab Tevatron collider. The production cross section for events with a central pseudorapidity gap of width $Δη^0>3$ (overlapping $η=0$) is found to be $4.43\pm 0.02{(stat)}{\pm 1.18}{(syst) mb}$ [$3.42\pm 0.01{(stat)}{\pm 1.09}{(syst) mb}$] at $\sqrt{s}=1800$ [630] GeV. Our results are compared with previous measurements and with predictions based on Regge theory and factorization.
We summarize the results of several searches for evidence of new physics phenomena using proton-proton collisions at 7 TeV delivered by the Large Hadron Collider at CERN and recorded by the CMS detector in 2011.
In keeping with the "find the Higgs" bandwagon, due to embark together with the Large Hadron Collider (LHC), we investigate discovery prospects with Higgs produced in conjunction with two top quarks decaying in the dilepton channel. The following is a brief account of adventures along the way; the interested reader may find more in our CMS note.
The Compact Muon Solenoid (CMS) detector is one of two general-purpose detectors that reconstruct the products of high energy particle interactions at the Large Hadron Collider (LHC) at CERN. The silicon pixel detector is the innermost component of the CMS tracking system. It determines the trajectories of charged particles originating from the interaction region in three points with high resolution enabling precise momentum and impact parameter measurements in the tracker. The pixel detector is exposed to intense ionizing radiation generated by particle collisions in the LHC. This irradiation…
The potential for top quark physics of the ATLAS and CMS experiments at the Large Hadron Collider is surveyed ranging from top quark "re-discovery" and its use as a calibration tool to initial and later stage measurements.
Results by the CMS Collaboration on forward physics, diffraction, and physics in the small-$x$ limit of quantum chromodynamics (QCD), are presented. In particular, results on azimuthal angle decorrelations between two jets in events where two outermost jets are separated by a large rapidity interval are discussed. In addition, results based on the production of two jets separated by a large rapidity gap (interval void of radiation) are presented. These dijet production processes are expected to be sensitive to Balitsky-Fadin-Kuraev-Lipatov (BFKL) evolution effects. We highlight results on incl…
The Compact Muon Solenoid (CMS) Experiment is a general purpose particle detector experiment located at the Large Hadron Collider (LHC) at CERN. In 2008, the LHC beam was commissioned and successfully steered through the CMS detector. First results from CMS with beam data are described, focusing on detector commissioning with beam data, from beam halo studies with the endcap muon system to displays of "beam splash" events, in which the proton beam was stopped by an upstream collimator.
From particle identification to the discovery of the Higgs boson, deep learning algorithms have become an increasingly important tool for data analysis at the Large Hadron Collider (LHC). We present an innovative end-to-end deep learning approach for jet identification at the Compact Muon Solenoid (CMS) experiment at the LHC. The method combines deep neural networks with low-level detector information, such as calorimeter energy deposits and tracking information, to build a discriminator to identify different particle species. Using two physics examples as references: electron vs. photon discr…
The Large Hadron Collider is an ideal place for precision measurements of the properties of the electroweak gauge bosons W^\pm, Z^0, as well as of the top quark. In this article, a few highlights of the prospects for performing such measurements with the CMS detector are summarized, with an emphasis on the first few 1/fb of data.
The capabilities of the ATLAS, CMS and LHCb detectors to reconstruct jets at forward rapidities (|η|> 3) in p-p collisions at the CERN Large Hadron Collider are reviewed. The QCD and Higgs physics motivations for such measurements are summarised. Details are given on studies that provide information on the parton structure and evolution at small values of fractional momenta in the proton.
The most recent results on top-quark physics reported by the CMS experiment at the Large Hadron Collider (LHC) are presented in this talk. The results are based on a data sample of about 36/pb of data collected during 2010 at a pp center-of-mass energy of 7 TeV.
We present heavy flavor measurements performed by the ATLAS and CMS Collaborations with data collected at the Large Hadron Collider. The production mechanism of heavy flavor hadrons is discussed as well as lifetime measurements and searches for the rare decay Bs->mumu. The large available statistics of about 5 fb-1 per experiment collected during the year 2011 together with the excellent detector performance allows to perform competitive heavy flavor measurements.
The production of jets at the Large Hadron Collider (LHC) at TeV centre-of-mass energy is summarized, including results from both the ATLAS and CMS detectors. Current jet performance is described, followed by inclusive jet and multi-jet measurements in various final state configurations. Finally some results on heavy flavour and jet substructure are presented.
Forward physics with CMS at the LHC covers a wide range of physics subjects, including very low-x QCD, underlying event and multiple interactions characteristics, gamma-mediated processes, shower development at the energy scale of primary cosmic ray interactions with the atmosphere, diffraction in the presence of a hard scale and even MSSM Higgs discovery in central exclusive production. We describe the forward detector instrumentation around the CMS interaction point and present selected feasibility studies to illustrate their physics potential.
We present an overview of measurements of electroweak vector boson pair production and anomalous Triple Gauge Couplings (aTGC), with semileptonic and fully leptonic final states. The data analyzed were taken at center of mass energy of 7 & 8 TeV by the CMS detector at the Large Hadron Collider. The cross-section measurements are important because they are test of the Standard Model predictions, while these processes serve as background for Higgs searches and various other processes.
After a brief overview of the Compact Muon Solenoid (CMS) experiment, the status of construction and installation is described in the first part of the note. The second part of the document is devoted to a discussion of the general commissioning strategy of the CMS experiment, with a particular emphasis on trigger, calibration and alignment. Aspects of b-physics, as well as examples for early physics with CMS are also presented. CMS will be ready for data taking in time for the first collisions in the Large Hadron Collider (LHC) at CERN in late 2007.
A prospective analysis for the search of the Standard Model Higgs boson decaying in vector boson pairs is presented with the CMS experiment in the context of the initial luminosity at the CERN LHC pp collider. Monte Carlo data corresponding to an integrated luminosity of up to 1 fb$^{-1}$ are analysed and the expected significance for a Standard Model-like Higgs boson in these channels is established.
In this article we describe the methods of observing WZ signal at CMS experiment at Large Hadron Collider. To reduce the dependence on Monte Carlo simulation we use data-driven techniques and estimate that 5sigma significance of WZ signal can be reached with less than 350 pb^{-1} at 95% C.L. for sqrt{s} = 14 TeV. We also overview several models that would yield anomalous production of the WZ final state, sensitivity to which can be achieved with less data.
Results on diffraction from the Fermilab Tevatron collider obtained by the CDF II Collaboration using data from proton-antiproton collisions at a c.m.s. energy of 1.96 TeV are reviewed and compared with theoretical expectations. Implications for predictions of exclusive Higgs boson production rates at the Large Hadron Collider are discussed.
The CMS detector is one of the two general purpose experiments that will study the collisions produced by the Large Hadron Collider (LHC). The LHC is supposed to start its operation in 2007 at an instantaneous luminosity of 2 x 10^33 cm-2 s-1, which may well result in an integrated luminosity of 10 fb-1 after the first year of running. The corresponding physics reach of CMS is exemplified with the study of a few standard model channels (weak boson and top quark production) and with the searches for Higgs bosons.
Results on soft and hard diffraction obtained by the CDF Collaboration in Run I of the Fermilab Tevatron pbar-p collider are reviewed and compared with results from the DESY e-p collider HERA and with theoretical expectations. In addition, the CDF program for diffractive studies in Run II is briefly reviewed with emphasis on the relevant detector upgrades and physics goals.
From 1992 to 2007, HERA, the first electron-proton collider, operated at cms energies of about 320 GeV and allowed the investigation of deep-inelastic and photoproduction processes at the highest energy scales accessed thus far. This review is an introduction to, and a summary of, the main results obtained at HERA during its operation.
Thanks to the excellent tracking and muon identification performance, combined with a flexible trigger system, the CMS experiment at the Large Hadron Collider is conducting a rich and competitive program of measurements in the field of heavy flavor physics. We review the status of b-quark production cross section measurements in inclusive and exclusive final states, the measurement of B hadron angular correlations, the search for rare $B^0_s$ and $B^0$ decays to dimuons, and the observation of the X(3872) resonance.
We plan to add high precision tracking- and timing-detectors at z = +/- 240 m to CMS to study exclusive processes p + p -- p + X + p at high luminosity. This enables the LHC to be used as a tagged photon-photon collider, with X = l+l- and W+W-, and as a "tagged" gluon-gluon collider (with a spectator gluon) for QCD studies with jets. A second stage at z = 240 m would allow observations of exclusive Higgs boson production.
At the Large Hadron Collider at CERN the proton bunches cross at a rate of 40MHz. At the Compact Muon Solenoid experiment the original collision rate is reduced by a factor of O (1000) using a Level-1 hardware trigger. A subsequent factor of O(1000) data reduction is obtained by a software-implemented High Level Trigger (HLT) selection that is executed on a multi-processor farm. In this review we present in detail prototype CMS HLT physics selection algorithms, expected trigger rates and trigger performance in terms of both physics efficiency and timing.
After nearly two decades of design, construction and commissioning, the CMS detector was operated with colliding LHC proton beams for the first time in November 2009. Collision data were recorded at centre-of-mass energies of 0.9 and 2.36 TeV, and analyzed with a fast turn-around time by the CMS collaboration. In this talk I will present a selection of commissioning results and striking first physics resonances observed. Then I will discuss the analysis of the transverse momentum and rapidity distribution of charged hadrons, which led to the first CMS physics publication. The excellent perform…
A search for the standard model Higgs boson in the \bbbar decay channel has been carried out with the CMS detector at the LHC collider. The searched production modes are the associated VH production, the VBF production and the production in association with top quark pairs (ttH). The analyses are based on pp collision data collected at centre-of-mass energies of 7 and 8 TeV, corresponding to integrated luminosities of 5 fb$^{-1}$ and 20 fb$^{-1}$, respectively. The strategy and results of the searches are reported.
Two recent observations of new b hadrons in pp collisions at \sqrt{s} = 7 TeV at the Large Hadron Collider (LHC) are presented. The ATLAS collaboration has observed a new state in radiative transitions to Υ(1S) and Υ(2S) and interprets this as the first observation of the χ_b(3P) states. The CMS collaboration has observed a new b baryon decaying to Ξ_b-π+ (plus charge conjugates). This is interpreted as a neutral J^P = 3/2^+ Ξ_b* baryon.
The identification of jets originating from b quarks is crucial both for the searches for new physics and for the measurement of standard model processes. The Compact Muon Solenoid (CMS) collaboration at the Large Hadron Collider (LHC) has developed a variety of algorithms to select b-quark jets based on variables such as the impact parameter of charged particle tracks, properties of reconstructed secondary vertices from heavy hadron decays, and the presence or absence of a lepton in the jet, or combinations thereof. Performance measurements of these b-jet identification algorithms are present…
Recent measurements of Higgs boson cross-section and properties are presented using up to $139~\text{fb}^{-1}$ of proton-proton collision data delivered by the Large Hadron Collider at $\sqrt{s}~=~13~\text{TeV}$ and recorded by the ATLAS and CMS detectors. Three measurements are discussed. The first is the measurement of Higgs boson production with sizeable transverse momentum decaying to a $b\bar{b}$ pair. The remaining two measurements exploit the $H \rightarrow WW^*$ decay channel in various production modes: gluon fusion, vector boson fusion, and production in association with a $W$ or $Z$…
Results on diffraction obtained by the CDF Collaboration in Run I of the Fermilab Tevatron $\bar pp$ collider are reviewed. New results are reported on soft double diffraction and diffractive $J/ψ$ production. The CDF program for diffractive studies in Run II is briefly discussed.
Results on hard diffraction from HERA and proton-antiproton Colliders are reviewed with emphasis on the factorization properties of the diffractive structure function of the proton and on the structure of the pomeron.
In this proceeding, an overview of the recent progress of the exotic hadrons studies at hadron colliders is presented, including the experimental measurement results from CMS, LHCb, CDF and D0. The talk covers the physics properties study of X(3872); the search for Y(4140) state etc; the recent result of Z(4430); and also the extended study to bottomonium sector.
A general review of the latest results about single and double vector boson production in the multipurpose experiments at LHC (ATLAS and CMS) and at Tevatron (CDF and D0) will be presented. The review will focus on boson production, while a more detailed report about W and Z properties can be found elsewhere. Only leptonic decays into electrons and muons will be considered.
The ATLAS and CMS experiments have collected data at the CERN Large Hadron Collider (LHC) since December 2009, and with a collision energy \sprts=7 TeV since March 2010. Both detectors work remarkably well at this early stage of operation, and several physics analyses have already been published. It is currently expected that an integrated luminosity of ~1 fb-1 will be collected before a 15 month shutdown from early 2012, and that up to 10 (100) fb-1 will be collected at a collision energy at or near \sqrts=14 Tev by the end of 2013 (2016). Taking account of the outstanding Tevatron results ob…
The CMS experiment uses missing E_T to both measure processes in the Standard Model and test models of physics beyond the Standard Model. These proceedings show the performance of the missing E_T reconstruction evaluated by using 4.6 fb-1 of proton-proton collision data at the center-of-mass energy 7 TeV collected in 2011 with the CMS detector at the Large Hadron Collider. Missing E_T was reconstructed based on a particle-flow technique. Jet energy corrections were propagated to missing E_T. After anomalous signals and events were addressed, the missing E_T spectrum was well reproduced by MC s…
The diffractive program of the CDF Collaboration at the Fermilab Tevatron pbar-p Collider is reviewed with emphasis on recent results from Run-II and future prospects.
Top quarks can be produced abundantly at hadron colliders like the Tevatron at Fermilab and the Large Hadron Collider at CERN, and a variety of measurements of top-quark properties have been gathered in the recent years from four experiments: CDF and D0 at the Tevatron and ATLAS and CMS at the Large Hadron Collider. In this review the most recent results on the measurement of the top-quark mass by the four different collaborations, with various techniques and considering different topologies, are reported.
The Large Hadron Collider (LHC), scheduled to start operation in 2006, is foreseen to provide in the first year of running a total of $\sim 10^{12}$ $τ$ leptons. CMS (Compact Muon Solenoid) is a general-purpose experiment designed to study proton-proton and heavy-ion collisions at LHC. Even if the Susy particles and Higgs searches togheter with the B-physics present its main goal, the large amount of $τ$-lepton, could allow a systematic study of tau-physics. We have performed a full simulation of CMS using GEANT 3 package and the object-oriented reconstruction program ORCA to study the sensiti…
We describe recent results from CMS and TOTEM on hard diffraction, diffractive jets and jet gap jet events. We also give the first sensitivities and limits on quartic anomalous couplings and axion-like particles at high mass using the LHC as a $γγ$ collider. The predicted sensitivities with 300 fb$^{-1}$ are better by two or three orders of magnitude compared to the more standard methods at the LHC without measuring intact protons after collision
The two calorimeters CASTOR and ZDCs enhance the hermeticity of the CMS detector at the LHC by extending the rapidity coverage in the forward region. After having described these detectors, their forward physics capabilities are presented. These latters include the study of parton shower, multiple parton interactions, diffraction and ultra high energy cosmic rays models. The processes to be measured to constrain these topics are multi-jet events with a forward jet, central-forward activity correlation, rapidity gaps and forward neutron production.
In 2016, the Large Hadron Collider provided proton-proton collisions at 13 TeV center-of-mass energy and achieved very high luminosity and reliability. The performance of the CMS Experiment in this running period and a selection of recent physics results are presented. These include precision measurements and searches for new particles. The status and prospects for data-taking in 2017 and a brief summary of the highlights of the High Luminosity (HL-LHC) upgrade of the CMS detector are also presented.
We present recent measurements of multijet correlations using forward and low-$p_{\mathrm{T}}$ jets performed by the CMS collaboration at the LHC collider. In pp collisions at $\sqrt{s} = 7$ TeV, azimuthal correlations in dijets separated in rapidity by up to 9.4 units were measured. The results are compared to BFKL- and DGLAP-based Monte Carlo generator and analytic predictions. In pp collisions at $\sqrt{s} = 8$ TeV, cross sections for jets with $p_{\mathrm{T}}$ > 21 GeV and |y| < 4.7, and for track-jets with $p_{\mathrm{T}}$ > 1 GeV (minijets) are presented. The minijet results are sensitiv…
The CMS experiment at the Large Hadron Collider collected in the first months of operation a luminosity of about 300/nb. The first results in the context of the B physics obtained with these data are presented. The di-muon resonances from J/psi and Y decays are presented and their total and differential cross-sections measured. The inclusive B production have also being investigated and two independent measurements are reported. Muons in jets are used as a way to identify events with B content, the kinematic properties (ptRel) of the muons are used to separate the B production from other proce…
