# PH-EP Articles

2013-05-17
11:55
 Study of $B^{0} \rightarrow D^{*-}\pi^{+}\pi^{-}\pi^{+}$ and $B^{0} \rightarrow D^{*-}K^{+}\pi^{-}\pi^{+}$ decays / LHCb Collaboration Using proton-proton collision data collected by the LHCb experiment at $\sqrt{s} =$ 7 TeV, corresponding to an integrated luminosity of 1.0 fb$^{-1}$, the ratio of branching fractions of the $B^{0}\rightarrow D^{*-}\pi^{+}\pi^{-}\pi^{+}$ decay relative to the $B^{0} \rightarrow D^{*-}\pi^{+}$ decay is measured to be \begin{equation*} \frac{\mathcal{B}(B^{0}\rightarrow D^{*-}\pi^{+}\pi^{-}\pi^{+})}{\mathcal{B}(B^{0} \rightarrow D^{*-}\pi^{+})} = 2.64 \pm 0.04\,(\text{stat.}) \pm 0.13\,(\text{syst.})\, . \label{eq:CF_BF_ratio_result} \end{equation*} The Cabibbo-suppressed decay $B^{0}\rightarrow D^{*-}K^{+}\pi^{-}\pi^{+}$ is observed for the first time and the measured ratio of branching fractions is \begin{equation*} \frac{\mathcal{B}(B^{0}\rightarrow D^{*-}K^{+}\pi^{-}\pi^{+})}{\mathcal{B}(B^{0} \rightarrow D^{*-}\pi^{+}\pi^{-}\pi^{+})} = (6.47 \pm 0.37\,(\text{stat.}) \pm 0.35\,(\text{syst.})) \times 10^{-2} \label{eq:CS_BF_ratio_result}\, . [...] arXiv:1303.6861; LHCB-PAPER-2012-046; CERN-PH-EP-2013-041.- Geneva : CERN, 2013 - 17 p. - Published in : Phys. Rev. D 87 (2013) 092001 APS Open Access article: PDF; Related data file(s): ZIP; External link: Preprint

2013-05-02
14:05
 Measurement of the $B^0 \to K^{*0}e^+e^-$ branching fraction at low dilepton mass / LHCb Collaboration The branching fraction of the rate decay $B^0 \rightarrow K^{*0}e^+e^-$ in the dilepton mass region from 30 to 1000 MeV$/c^2$ has been measured by the LHCb experiment, using $pp$ collision data, corresponding to an integrated luminosity of 1.0 fb$^{-1}$, at a centre-of-mass energy of 7 TeV. The decay mode $B^0 \rightarrow J/\psi(e^+e^-) K^{*0}$ is utilized as a normalization channel. [...] arXiv:1304.3035; LHCB-PAPER-2013-005; CERN-PH-EP-2013-048.- Geneva : CERN, 2013 - 19 p. - Published in : J. High Energy Phys. 05 (2013) 159 Fulltext: PDF; Related data file(s): ZIP; Springer Open Access article: PDF; External link: Preprint

2013-04-23
16:41
 Precision measurement of the $B^0_s - \bar{B}^0_s$ oscillation frequency with the decay $B^0_s \to D^-_s \pi^+$ / LHCb Collaboration A key ingredient to searches for physics beyond the Standard Model in $B^{0}_{s}$ mixing phenomena is the measurement of the $B^{0}_{s}$-$\bar{B}^{0}_{s}$ oscillation frequency, which is equivalent to the mass difference $\Delta m_{s}$ of the $B^{0}_{s}$ mass eigenstates. Using the world's largest $B^{0}_{s}$ meson sample accumulated in a dataset, corresponding to an integrated luminosity of 1.0 fb$^{-1}$, collected by the LHCb experiment at the CERN LHC in 2011, a measurement of $\Delta m_{s}$ is presented. [...] arXiv:1304.4741; CERN-PH-EP-2013-054; LHCB-PAPER-2013-006.- Geneva : CERN, 2013 - 18 p. - Published in : New J. Phys. 15 (2013) 053021 Fulltext: PDF; IOP Open Access article: PDF; Related data file(s): ZIP; External link: Preprint

2013-04-18
09:41
 Searches for violation of lepton flavour and baryon number in tau lepton decays at LHCb / LHCb Collaboration Searches for the lepton flavour violating decay $\tau^-\to \mu^-\mu^+\mu^-$ and the lepton flavour and baryon number violating decays $\tau^-\to \bar{p}\mu^+\mu^-$ and $\tau^-\to p\mu^-\mu^-$ have been carried out using proton-proton collision data, corresponding to an integrated luminosity of $1.0$ fb$^{-1}$, taken by the LHCb experiment at $\sqrt{s} = 7$ TeV. No evidence has been found for any signal, and limits have been set at $90\%$ confidence level on the branching fractions: $\cal B(\tau^-\to \mu^-\mu^+\mu^-) < 8.0 \times 10^{-8}$, $\cal B(\tau^-\to \bar{p}\mu^+\mu^-) < 3.3 \times 10^{-7}$ and $\cal B(\tau^-\to p\mu^-\mu^-) < 4.4 \times 10^{-7}$. [...] arXiv:1304.4518; LHCB-PAPER-2013-014; CERN-PH-EP-2013-062.- Geneva : CERN, 2013 - 19 p. - Published in : Phys. Lett. B 724 (2013) xx Fulltext: PDF; Related data file(s): ZIP; Related supplementary data file(s): ZIP; External link: Preprint

2013-04-17
17:41
 Measurement of the effective $B_s^0\rightarrow J/\psi K_{\mathrm S}^0$ lifetime / LHCb Collaboration This paper reports the first measurement of the effective $B_s^0\rightarrow J/\psi K_{\mathrm S}^0$ lifetime and an updated measurement of its time-integrated branching fraction. Both measurements are performed with a data sample, corresponding to an integrated luminosity of $1.0\:\text{fb}^{-1}$ of $pp$ collisions, recorded by the LHCb experiment in 2011 at a centre-of-mass energy of $7\:\text{TeV}$. [...] arXiv:1304.4500; CERN-PH-EP-2013-063; LHCB-PAPER-2013-015.- Geneva : CERN, 2013 - 20 p. - Published in : Nucl. Phys. B 873 (2013) 275-292 Elsevier Open Access article: PDF; Fulltext: PDF; Related data file(s): ZIP; External link: Preprint

2013-04-11
12:43
 Limits on neutral Higgs boson production in the forward region in pp collisions at $\sqrt{s}=7$ TeV / LHCb Collaboration Limits on the cross-section times branching fraction for neutral Higgs bosons, produced in $pp$ collisions at $\sqrt{s} = 7$ TeV, and decaying to two tau leptons with pseudorapidities between 2.0 and 4.5, are presented. The result is based on a dataset, corresponding to an integrated luminosity of 1.0 $\mathrm{fb}^{-1}$, collected with the LHCb detector. [...] arXiv:1304.2591; LHCB-PAPER-2013-009; CERN-PH-EP-2013-058.- Geneva : CERN, 2013 - 14 p. - Published in : J. High Energy Phys. 05 (2013) 132 Fulltext: PDF; Related data file(s): ZIP; Springer Open Access article: PDF; External link: Preprint

2013-03-31
18:00
 Search for a standard-model-like Higgs boson with a mass of up to 1 TeV at the LHC / CMS Collaboration A search for a standard-model-like Higgs boson in the H $\to$ WW and H $\to$ ZZ decay channels is reported, for Higgs boson masses in the range 145 < $m_H$ < 1000 GeV. The search is based upon proton-proton collision data samples corresponding to an integrated luminosity of up to 5.1 inverse femtobarns at $\sqrt{s}$ = 7 TeV and up to 5.3 inverse femtobarns at $\sqrt{s}$ = 8 TeV, recorded by the CMS experiment at the LHC. [...] arXiv:1304.0213; CMS-HIG-12-034; CERN-PH-EP-2013-050.- Geneva : CERN, 2013 - 43 p. - Published in : Eur. Phys. J. C 73 (2013) 2469 Fulltext: PDF; External link: Preprint

2013-03-20
12:13
 Observation of the suppressed ADS modes $B^\pm \to [\pi^\pm K^\mp \pi^+\pi^-]_D K^\pm$ and $B^\pm \to [\pi^\pm K^\mp \pi^+\pi^-]_D \pi^\pm$ / LHCb Collaboration An analysis of $B^{\pm}\to DK^{\pm}$ and $B^{\pm}\to D\pi^{\pm}$ decays is presented where the $D$ meson is reconstructed in the four-body final state $K^{\pm}\pi^{\mp} \pi^+ \pi^-$. Using LHCb data corresponding to an integrated luminosity of $1.0{\rm \,fb}^{-1}$, first observations are made of the suppressed ADS modes $B^{\pm}\to [\pi^{\pm} K^{\mp}\pi^+\pi^-]_D K^{\pm}$ and $B^{\pm}\to [\pi^{\pm} K^{\mp} \pi^+\pi^- ]_D\pi^{\pm}$ with a significance of $5.1\sigma$ and greater than $10\sigma$, respectively. [...] arXiv:1303.4646; CERN-PH-EP-2013-038; LHCB-PAPER-2012-055.- Geneva : CERN, 2013 - 20 p. - Published in : Phys. Lett. B 723 (2013) 44-53 Elsevier Open Access article: PDF; Related data file(s): ZIP; External link: Preprint

2013-03-20
08:24
 Studies of jet mass in dijet and W/Z+jet events / CMS Collaboration Invariant mass spectra for jets reconstructed using the anti-kt and Cambridge-Aachen algorithms are studied for different jet "grooming" techniques in data corresponding to an integrated luminosity of 5 inverse femtobarns, recorded with the CMS detector in proton-proton collisions at the LHC at a center-of-mass energy of 7 TeV. Leading-order QCD predictions for inclusive dijet and W/Z+jet production combined with parton-shower Monte Carlo models are found to agree overall with the data, and the agreement improves with the implementation of jet grooming methods used to distinguish merged jets of large transverse momentum from softer QCD gluon radiation.. arXiv:1303.4811; CMS-SMP-12-019; CERN-PH-EP-2013-016.- Geneva : CERN, 2013 - 51 p. - Published in : J. High Energy Phys. 05 (2013) 090 Fulltext: PDF; Springer Open Access article: PDF; External link: Preprint

2013-03-15
13:10
 Search for rare $B^0_{(s)}\rightarrow \mu^+ \mu^- \mu^+ \mu^-$ decays / LHCb Collaboration A search for the decays $B^0_{s}\rightarrow \mu^+ \mu^- \mu^+ \mu^-$ and $B^0 \rightarrow \mu^+ \mu^- \mu^+ \mu^-$ is performed using data, corresponding to an integrated luminosity of 1.0 fb$^{-1}$, collected with the LHCb detector in 2011. The number of candidates observed is consistent with the expected background and, assuming phase-space models of the decays, limits on the branching fractions are set: ${\cal B}(B^0_{s}\rightarrow \mu^+ \mu^- \mu^+ \mu^-) < 1.6 \ (1.2) \times 10^{-8}$ and ${\cal B}(B^0 \rightarrow \mu^+ \mu^- \mu^+ \mu^-)< 6.6 \ (5.3) \times 10^{-9}$ at 95% (90%) confidence level. [...] arXiv:1303.1092; CERN-PH-EP-2013-031; LHCB-PAPER-2012-049.- Geneva : CERN, 2013 - 10 p. - Published in : Phys. Rev. Lett. 110 (2013) 1528276 APS Open Access article: PDF; Related data file(s): ZIP; External link: Preprint