# PH-EP Articles

Nyeste elementer:
2013-03-08
17:11
 Observation of the decay $B_c^+ \to \psi(2S)\pi^+$ / LHCb Collaboration The decay $B_c^+ \to \psi(2S)\pi^+$ with $\psi(2S) \to \mu^+\mu^-$ is observed with a significance of $5.2\,\sigma$ using $pp$ collision data corresponding to an integrated luminosity of 1.0 $fb^{-1}$ collected by the LHCb experiment. The branching fraction of $B_c^+ \to \psi(2S)\pi^+$ decays relative to that of the $B_c^+ \to J/\psi\pi^+$ mode is measured to be \begin{equation*} \frac{\mathcal{B}(B_c^+ \to \psi(2S)\pi^+)}{\mathcal{B}(B_c^+ \to J/\psi\pi^+)} = 0.250 \pm 0.068 \,\text{stat} \pm 0.014 \,\text{\syst} \pm 0.006 \,(\mathcal{B}). [...] arXiv:1303.1737; LHCB-PAPER-2012-054; CERN-PH-EP-2013-028.- Geneva : CERN, 2013 - 12 p. - Published in : Phys. Rev. D 87 (2013) 071103 APS Open Access article: PDF; Related data file(s): ZIP; External link: Preprint

2013-02-27
11:54
 Observation of the $B^0_{s}\to\psi{(2\mathrm{S})}\eta$ and $B^0_{(s)}\to\psi{(2\mathrm{S})}\pi^+\pi^-$ decays / LHCb Collaboration First observations of the $B^0_s \rightarrow \psi(2S) \eta$, $B^0 \rightarrow \psi(2S) \pi^+ \pi^-$ and $B^0_s \rightarrow \psi(2S) \pi^+ \pi^-$ decays are made using a dataset corresponding to an integrated luminosity of 1.0 $fb^{-1}$ collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=7$ TeV. The ratios of the branching fractions of each of the $\psi(2S)$ modes with respect to the corresponding $J/\psi$ decays are $\frac{\mathcal{B}(B^0_s \rightarrow \psi(2S) \eta) }{\mathcal{B}(B^0_s \rightarrow J/\psi \eta)} =0.83\pm0.14\,(stat)\pm0.12\,(syst)\pm0.02\,(\mathcal{B}),$ $\frac{\mathcal{B}(B^0 \rightarrow \psi(2S) \pi^+ \pi^-)}{\mathcal{B}(B^0 \rightarrow J/\psi \pi^+ \pi^-)} =0.56\pm0.07\,(stat)\pm0.05\,(syst)\pm0.01\,(\mathcal{B}),$ $\frac{\mathcal{B}(B^0_s \rightarrow \psi(2S) \pi^+ \pi^-)}{\mathcal{B}(B^0_s \rightarrow J/\psi \pi^+ \pi^-)} =0.34\pm0.04\,(stat)\pm0.03\,(syst)\pm0.01\,(\mathcal{B}),$ where the third uncertainty corresponds to the uncertainties of the dilepton branching fractions of the $J/\psi$ and $\psi$(2S) meson decays.. arXiv:1302.6354; CERN-PH-EP-2013-024; LHCB-PAPER-2012-053.- Geneva : CERN, 2013 - 16 p. - Published in : Nucl. Phys. B 871 (2013) 403-419 Elsevier Open Access article: PDF; Related data file(s): ZIP; External link: Preprint

2013-02-11
19:15
 Study of the underlying event at forward rapidity in pp collisions at $\sqrt{s}$ = 0.9, 2.76, and 7 TeV / CMS Collaboration The underlying event activity in proton-proton collisions at forward pseudorapidity (-6.6 $\lt \eta \lt$ -5.2) is studied with the CMS detector at the LHC, using a novel observable: the ratio of the forward energy density, dE/d$\eta$, for events with a charged-particle jet produced at central pseudorapidity (abs(eta[jet]) $\lt$ 2) to the forward energy density for inclusive events. This forward energy density ratio is measured as a function of the central jet transverse momentum, pt, at three different pp centre-of-mass energies ($\sqrt{s}$ = 0.9, 2.76, and 7 TeV). [...] arXiv:1302.2394; CMS-FWD-11-003; CERN-PH-EP-2013-012.- Geneva : CERN, 2013 - 33 p. - Published in : J. High Energy Phys. 04 (2013) 072 Springer Open Access article: PDF; External link: Preprint

2013-01-30
16:51
 A Particle Consistent with the Higgs Boson Observed with the ATLAS Detector at the Large Hadron Collider / ATLAS Collaboration Nearly 50 years ago, theoretical physicists proposed that a field permeates the universe and gives energy to the vacuum. This field was required to explain why some, but not all, fundamental particles have mass. [...] CERN-PH-EP-2012-303.- Geneva : CERN, 2012 - 8 p. - Published in : Science 338 (2012) 1576-1582 Fulltext: PDF PDF (PDFA); External links: Previous draft version; Supplementary Materials

2013-01-25
14:22
 Measurement of the $t\bar{t}$ production cross section in the $\tau$+jets channel in pp collisions at $\sqrt{s}$ = 7 TeV / CMS Collaboration The top-quark pair production cross section in 7 TeV centre-of-mass proton proton collisions is measured using data collected by the CMS detector at the LHC. The measurement uses events with one jet identified as a hadronically-decaying tau lepton and at least four additional energetic jets, at least one of which is identified as coming from a b quark. [...] arXiv:1301.5755; CMS-TOP-11-004; CERN-PH-EP-2012-374.- Geneva : CERN, 2013 - 27 p. - Published in : Eur. Phys. J. C 73 (2013) 2386 Springer Open Access article: PDF; External link: Preprint

2013-01-25
13:31
 Analysis of the resonant components in $\overline{B}^0 \to J/\psi \pi^+ \pi^-$ / LHCb collaboration Interpretation of CP violation measurements using charmonium decays, in both the B0 and Bs systems, can be subject to changes due to "penguin" type diagrams. These effects can be investigated using measurements of the Cabibbo-suppressed B0->J/\psi pi+pi- decays. [...] arXiv:1301.5347; LHCB-PAPER-2012-045; CERN-PH-EP-2013-004.- Geneva : CERN, 2013 - 38 p. - Published in : Phys. Rev. D 87 (2013) 052001 APS Open Access article: PDF; Related data file(s): ZIP; External link: Preprint

2013-01-20
23:18
 Measurement of $W^+W^-$ and ZZ production cross sections in pp collisions at $\sqrt{s}$=8 TeV / CMS Collaboration The W+W- and ZZ production cross sections are measured in proton-proton collisions at $\sqrt{s}$ = 8 TeV with the CMS experiment at the LHC in data samples corresponding to an integrated luminosity of up to 5.3 inverse femtobarns. The measurements are performed in the leptonic decay modes W+W- to l' nu l' nu and ZZ to 2l 2l', where l = e, mu and l' = e, mu, tau. [...] arXiv:1301.4698; CMS-SMP-12-024; CERN-PH-EP-2012-376.- Geneva : CERN, 2013 - Published in : Phys. Lett. B 721 (2013) 190-211 Elsevier Open Access article: PDF; External link: Preprint

2012-12-30
15:58
 Measurement of the $t\bar{t}$ production cross section in pp collisions at $\sqrt{s}$ = 7 TeV with lepton + jets final states / CMS Collaboration A measurement of the t t-bar production cross section in pp collisions at $\sqrt{s}$ = 7 TeV is presented. The results are based on data corresponding to an integrated luminosity of 2.3 inverse femtobarns collected by the CMS detector at the LHC. [...] arXiv:1212.6682; CMS-TOP-11-003; CERN-PH-EP-2012-285.- Geneva : CERN, 2013 - 31 p. - Published in : Phys. Lett. B 720 (2013) 83-104 Elsevier Open access article: PDF; External link: Preprint

2012-12-28
17:40
 A search for prompt lepton-jets in pp collisions at $\sqrt{s}$ = 7 TeV with the ATLAS detector / ATLAS Collaboration We present a search for a light (mass < 2 GeV) boson predicted by Hidden Valley supersymmetric models that decays into a final state consisting of collimated muons or electrons, denoted "lepton-jets". The analysis uses 5fb-1 of $\sqrt{s}$ = 7 TeV proton--proton collision data recorded by the ATLAS detector at the Large Hadron Collider to search for the following signatures: single lepton-jets with at least four muons; pairs of lepton-jets, each with two or more muons; and pairs of lepton-jets with two or more electrons. [...] arXiv:1212.5409; CERN-PH-EP-2012-319.- Geneva : CERN, 2013 - 24 p. - Published in : Phys. Lett. B 719 (2013) 299-317 Elsevier Open Access article: PDF; External links: Previous draft version; Preprint

2012-12-28
15:56
 Search for supersymmetry in pp collisions at $\sqrt{s}$ = 7 TeV in events with a single lepton, jets, and missing transverse momentum / CMS Collaboration Results are reported from a search for new physics processes in events containing a single isolated high-transverse-momentum lepton (electron or muon), energetic jets, and large missing transverse momentum. The analysis is based on a 4.98 inverse femtobarn sample of proton-proton collisions at a center-of-mass energy of 7 TeV, obtained with the CMS detector at the LHC. [...] arXiv:1212.6428; CMS-SUS-12-010; CERN-PH-EP-2012-348.- Geneva : CERN, 2013 - 59 p. - Published in : Eur. Phys. J. C 73 (2013) 2404 Springer Open Access article: PDF; External link: Preprint