CMS Forward and small-x QCD Physics Results

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• Last Postings

2012 Plots and Results:

• Very forward energy flow in CASTOR in p-p collisions at $\sqrt{\rm{S}}$ = 0.9, 2.76, 7 TeV

• Identified pi/k/p spectra in p-p collisions at $\sqrt{\rm{S}}$ = 0.9, 2.76, 7 TeV

• Measurement of the inelastic pp cross section at $\sqrt{\rm{s}} = 7 \mbox{ TeV}$ (via single-side triggers)

• Exclusive diphotons and dielectrons in pp collisions at $\sqrt{\rm{S}}$ = 7 TeV

• Evidence for hard-diffractive dijet production in pp collisions at $\sqrt{\rm{S}}$ = 7 TeV

• Forward jets and forward-central dijets in pp collisions at $\sqrt{\rm{S}}$ = 7 TeV

• Exclusive dimuons in pp collisions at $\sqrt{\rm{S}}$ = 7 TeV

• Measurement of the inelastic pp cross section at $\sqrt{\rm{s}} = 7 \mbox{ TeV}$ (via pileup event counting)

A new method to measure the inelastic pp cross section has been developed based on the assumption that pile-up events are randomly distributed according to a Poisson probability.

• Measurement of the exclusive two-photon production of muon pairs at the LHC

The first measurement is reported of the exclusive two-photon production of muon pairs in proton-proton collisions at 7TeV

• Forward Energy Flow and Central Track Multiplicities in W and Z boson Events at 7 TeV pp Collisions

In this paper we study the energy flow in the forward detectors, and the correlations of the forward energy flow with the track multiplicity in the central detector using events with centrally produced and bosons, identified with their leptonic decays. The observed forward energy deposits, their correlations and the track multiplicities in the central part of the CMS experiment are compared with different Monte Carlo models

• Forward energy flow

A measurement of the energy flow in the forward region of the CMS detector at the LHC is presented for centre-of-mass energies of 900 GeV and 7000 GeV.

• Measurement of forward jets

We report on a measurement of the cross section of inclusive forward jets in proton-proton collisions at ~=~7~TeV, with 3.14~pb integrated luminosity. Jets are reconstructed with the anti- algorithm (size ~0.5) in the Hadronic Forward calorimeters at pseudorapidities 3.2 4.7, in the transverse momentum range ~35 -- 150~GeV/c. The measurement is compared to next-to-leading order perturbative Quantum Chromodynamics calculations, to PYTHIA and HERWIG parton shower event generators, as well as to the CASCADE Monte Carlo.

* Cross section measurement for simultaneous production of a central and a forward jet in proton collisions at sqrt(s)=7 TeV

The measurement of the cross section for the production of pairs of jets, with one of them in the central region and the other one in the forward region of the CMS detector at LHC, in proton-proton collision at =~7~TeV, is presented using a luminosity of 3.14~pb. The jets are selected if they have transverse momentum ~35~GeV and axis within pseudorapidity ~4.7. The differential cross sections for the central and forward jets are compared to various Monte Carlo predictions.

* Observation of diffraction in proton-proton collisions at 7~TeV centre-of-mass energies at the LHC
The observation of inclusive diffraction at LHC with the CMS detector at s=7~TeV is presented, along with a comparison of the data with the predictions of the {\sc Pythia6}, {\sc Pythia8} and {\sc Phojet} generators.

• Event displays of W and Z Bosons with Large Rapidity Gaps

• Measurement of the energy flow in the forward region at the LHC
  A measurement is presented of the energy flow in the forward region of the CMS detector at the LHC for centre-of-mass energies sqrt(s) of 900 GeV, 2360 GeV and 7000 GeV. The energy flow is measured in two different event classes: in minimum bias events and in events with a hard scale provided by a dijet system at central pseudorapidities and with transverse energy ETjet>8 GeV at sqrt(s) of 900 GeV and 2360 GeV and with ETjet >20 GeV at sqrt(s) of 7000 GeV.

• Observation of diffraction in proton-proton collisions at 900 and 2360 GeV centre-of-mass energies at the LHC
  The observation of inclusive diffraction at LHC with the CMS detector at s=900 and 2360~GeV is presented, along with a comparison of the data with the predictions of the {\sc Pythia} and {\sc Phojet} generators..

2011 Results

Analysis	Approved Plots	CDS Entry	Luminosity	Comment
Measurement of the inelastic pp cross section at √s = 7 TeV with the CMS detector	FWD-11-001	PAS-11-001	36/pb	Journal: PLB, Conference:Moriond2011
Measurement of the inclusive production cross sections for forward jets and for dijet events with one forward and one central jet in pp collisions at √s = 7 TeV	CMS-FWD-11-002	PAS-11-002	3.14/pb	Journal: JHEP arXiv:1202.0704, Conference:QM2011
Search for central exclusive γγ production and observation of central exclusive e+e− production in pp collisions at √s = 7 TeV	FWD-11-004	PAS-11-004	36/pb

2010 Results

Analysis	Approved Plots	CDS Entry	Luminosity	Comment
Observation of diffraction in proton-proton collisions at 900 and 2360 GeV centre-of-mass energies at the LHC	FWD-10-001	PAS-10-001	10/μb, 0.4/μb	https://twiki.cern.ch/twiki/bin/view/CMS/InclusiveDiffraction7TeV
Measurement of the energy flow at large pseudorapidity at the LHC at √s=900, 2360 and 7000 GeV	FWD-10-002	PAS-10-002
Inclusive forward jet production cross sections in proton–proton collisions at √s = 7 TeV	FWD-10-003	PAS-10-003	3.14/pb	Conference:Moriond2011
Evidence for hard-diffractive dijet production in pp collisions at √s = 7 TeV	FWD-10-004	PAS-10-004	2.7/nb	Conference:Moriond2012
Measurement of exclusive γγ → μ+μ− production at √s = 7 TeV	CMS-FWD-10-005	PAS-10-005	40/pb	Journal: JHEP arXiv:1111.5536, Conference:Moriond2011
Cross section measurement for simultaneous production of a central and a forward jet in proton-proton collisions at √s =7 TeV	FWD-10-006	PAS-10-006	3.14/pb	Conference:Moriond2011
Observation of diffraction in proton-proton collisions at 7 TeV centre-of-mass energies at the LHC	FWD-10-007	PAS-10-007	20/μb
Forward Energy Flow, Central Track Multiplicities and Large Rapidity Gaps in W and Z Boson Events at 7 TeV pp Collisions	CMS-FWD-10-008	PAS-10-008	36/pb	Journal:EPJC arXiv:1110.0181v1, Conference:Moriond2011
Forward energy flow in the CMS detector	CMS-FWD-10-011	PAS-10-011	239/μb, 206/μb	Journal JHEP arXiv:1110.0211, Conference:Moriond2011
Measurement of inclusive and exclusive dijet production ratio at large rapidity intervals at √s = 7 TeV	FWD-10-014	PAS-10-014	5/pb	Journal:EPJC, Conference:EPS2011

Publications

• Papers
• Physics Analysis Summaries with collision data
• Physics Analysis Summaries from MC studies