Search for long-lived heavy charged particles using a ring imaging Cherenkov technique at LHCb

The paper is available here.

arXiv:1506.09173, LHCB-PAPER-2015-002

More detailed informationLHCb-ANA-2013-081

Abstract

A search is performed for heavy long-lived charged particles using 3.0 fb−1 of pp collisions collected at √s = 7 and 8 TeV with the LHCb detector. The search is mainly based on the response of the ring imaging Cherenkov detectors to distinguish the heavy, slow-moving particles from muons. No evidence is found for the production of such long-lived states. The results are expressed as limits on the Drell-Yan production of pairs of long-lived particles, with both particles in the LHCb pseudorapidity acceptance, 1.8 < η < 4.9. The mass-dependent cross-section upper limits are in the range 24 fb (at 95% CL) for masses between 124 and 309 GeV/c2 .

Figures

(Note, pdf and eps versions are available under attachments).

Caption Figure
Figure 1: Number of CMSP candidates, as a function of the four variables used as inputs to the ANN. The black dots with error bars show the 2012 data. The dashed red histogram is the expected shape for 124 GeV/c2 CMSPs and the blue histogram shows the background from Z/γ decays into muons. The energy in the VELO is given in units of minimum ionising particle (MIP) deposition. The first bin of the histogram for ∆E in the ECAL has been multiplied by a factor 0.25. fig1_dllx.pngfig1_ecal.pngfig1_hcal.png fig1_velo.png
Figure 2: Number of CMSP pairs, N , as a function of the pair significance corresponding to the CMSP mass of 124 GeV/c2, respectively. The black points with their statistical uncertainty show the 7 TeV (top) and 8 TeV (bottom) data sets. The red dashed histogram is the expected shape from CMSP pairs and the blue histogram the background; both are normalised to the number of events. The arrows indicate the chosen selection criteria. .fig2_124_7tev.png.fig2_124_8tev.png
Figure 2 cont: Number of CMSP pairs, N , as a function of the pair significance corresponding to the CMSP mass of 309 GeV/c2. The black points with their statistical uncertainty show the 7 TeV (top) and 8 TeV (bottom) data sets. The red dashed histogram is the expected shape from CMSP pairs and the blue histogram the background; both are normalised to the number of events. The arrows indicate the chosen selection criteria. .fig2_309_7tev.png.fig2_309_8tev.png
Figure 3: (top) DLLx distributions from muons selected from Z decays in data (black points) and simulation (blue histogram). The expected shape from a 124 GeV/c2 CMSP is shown in dashed red. (bottom) The simulated DLLx values are shifted in such a way that data and simulation have the same fraction of entries with DLLx > −5. fig3_a.pngfig3_b.png
Figure 4: The DLLx variable for: (top) protons selected above the Cherenkov threshold, p > 30 GeV/c, in data (black line) and simulation (blue points); (middle) and (bottom) below-threshold protons, p < 3.8 GeV/c, from data and simulation, respectively. The results from the fit of a Gaussian function plus polynomial to the below-threshold proton distributions are shown by the red curves. fig4_a.pngfig4_b.png fig4_c.png
Figure 5: DLLx for protons with p < 3.8 GeV/c. In black the result with nominal simulation parameters are shown. (top) The red, dashed, and green, dash-dot, plots are for a change by +20% and -20% of the photon yield; (bottom) is for a change by +40% (red, dashed) and -40% (green, dash-dot) of the random noise probability. fig5_a.pngfig5_b.png
Figure 6: Upper limits at 95% CL on the cross-sections for the pair production of CMSPs in the LHCb acceptance (points) and the corresponding predictions assuming the Drell-Yan production of τ (bands representing 1σ uncertainty) with SPS7 parameters, for pp collisions as a function of the CMSP mass at √s =7 and 8 TeV. fig6.png
-- KatharinaMueller - 2015-08-13
Topic attachments
I Attachment History Action Size Date Who Comment
Unknown file formateps fig1_dllx.eps r1 manage 94.8 K 2015-08-13 - 15:50 KatharinaMueller  
PDFpdf fig1_dllx.pdf r1 manage 10.0 K 2015-08-13 - 15:50 KatharinaMueller  
PNGpng fig1_dllx.png r1 manage 93.3 K 2015-08-13 - 15:50 KatharinaMueller  
Unknown file formateps fig1_ecal.eps r1 manage 97.4 K 2015-08-13 - 15:50 KatharinaMueller  
PDFpdf fig1_ecal.pdf r1 manage 11.7 K 2015-08-13 - 15:50 KatharinaMueller  
PNGpng fig1_ecal.png r1 manage 114.6 K 2015-08-13 - 15:50 KatharinaMueller  
Unknown file formateps fig1_hcal.eps r1 manage 98.0 K 2015-08-13 - 15:50 KatharinaMueller  
PDFpdf fig1_hcal.pdf r1 manage 12.1 K 2015-08-13 - 15:50 KatharinaMueller  
PNGpng fig1_hcal.png r1 manage 118.7 K 2015-08-13 - 15:50 KatharinaMueller  
Unknown file formateps fig1_velo.eps r1 manage 94.7 K 2015-08-13 - 15:51 KatharinaMueller  
PDFpdf fig1_velo.pdf r1 manage 10.3 K 2015-08-13 - 15:51 KatharinaMueller  
PNGpng fig1_velo.png r1 manage 100.8 K 2015-08-13 - 15:51 KatharinaMueller  
Unknown file formateps fig2_124_7tev.eps r1 manage 95.3 K 2015-08-13 - 15:51 KatharinaMueller  
PDFpdf fig2_124_7tev.pdf r1 manage 9.9 K 2015-08-13 - 15:51 KatharinaMueller  
PNGpng fig2_124_7tev.png r1 manage 93.4 K 2015-08-13 - 15:51 KatharinaMueller  
Unknown file formateps fig2_124_8tev.eps r1 manage 95.7 K 2015-08-13 - 15:51 KatharinaMueller  
PDFpdf fig2_124_8tev.pdf r1 manage 24.3 K 2015-08-13 - 15:51 KatharinaMueller  
PNGpng fig2_124_8tev.png r1 manage 92.4 K 2015-08-13 - 15:51 KatharinaMueller  
Unknown file formateps fig2_309_7tev.eps r1 manage 94.7 K 2015-08-13 - 15:52 KatharinaMueller  
PDFpdf fig2_309_7tev.pdf r1 manage 23.3 K 2015-08-13 - 15:52 KatharinaMueller  
PNGpng fig2_309_7tev.png r1 manage 90.5 K 2015-08-13 - 15:52 KatharinaMueller  
Unknown file formateps fig2_309_8tev.eps r1 manage 95.2 K 2015-08-13 - 15:52 KatharinaMueller  
PDFpdf fig2_309_8tev.pdf r1 manage 24.1 K 2015-08-13 - 15:52 KatharinaMueller  
PNGpng fig2_309_8tev.png r1 manage 93.6 K 2015-08-13 - 15:52 KatharinaMueller  
Unknown file formateps fig3_a.eps r1 manage 100.2 K 2015-08-13 - 15:53 KatharinaMueller  
PDFpdf fig3_a.pdf r1 manage 13.1 K 2015-08-13 - 15:53 KatharinaMueller  
PNGpng fig3_a.png r1 manage 111.4 K 2015-08-13 - 15:53 KatharinaMueller  
Unknown file formateps fig3_b.eps r1 manage 99.5 K 2015-08-13 - 15:53 KatharinaMueller  
PDFpdf fig3_b.pdf r1 manage 12.5 K 2015-08-13 - 15:53 KatharinaMueller  
PNGpng fig3_b.png r1 manage 93.7 K 2015-08-13 - 15:53 KatharinaMueller  
Unknown file formateps fig4_a.eps r1 manage 94.2 K 2015-08-13 - 15:53 KatharinaMueller  
PDFpdf fig4_a.pdf r1 manage 9.0 K 2015-08-13 - 15:53 KatharinaMueller  
PNGpng fig4_a.png r1 manage 75.6 K 2015-08-13 - 15:53 KatharinaMueller  
Unknown file formateps fig4_b.eps r1 manage 92.5 K 2015-08-13 - 15:53 KatharinaMueller  
PDFpdf fig4_b.pdf r1 manage 10.7 K 2015-08-13 - 15:53 KatharinaMueller  
PNGpng fig4_b.png r1 manage 71.2 K 2015-08-13 - 15:53 KatharinaMueller  
Unknown file formateps fig4_c.eps r1 manage 92.6 K 2015-08-13 - 15:53 KatharinaMueller  
PDFpdf fig4_c.pdf r1 manage 8.2 K 2015-08-13 - 15:53 KatharinaMueller  
PNGpng fig4_c.png r1 manage 76.5 K 2015-08-13 - 15:53 KatharinaMueller  
Unknown file formateps fig5_a.eps r1 manage 92.6 K 2015-08-13 - 15:53 KatharinaMueller  
PDFpdf fig5_a.pdf r1 manage 8.4 K 2015-08-13 - 15:53 KatharinaMueller  
PNGpng fig5_a.png r1 manage 88.5 K 2015-08-13 - 15:53 KatharinaMueller  
Unknown file formateps fig5_b.eps r1 manage 92.6 K 2015-08-13 - 15:54 KatharinaMueller  
PDFpdf fig5_b.pdf r1 manage 8.2 K 2015-08-13 - 15:54 KatharinaMueller  
PNGpng fig5_b.png r1 manage 86.4 K 2015-08-13 - 15:54 KatharinaMueller  
Unknown file formateps fig6.eps r1 manage 93.2 K 2015-08-13 - 15:54 KatharinaMueller  
PDFpdf fig6.pdf r1 manage 8.4 K 2015-08-13 - 15:54 KatharinaMueller  
PNGpng fig6.png r1 manage 123.2 K 2015-08-13 - 15:54 KatharinaMueller  
Edit | Attach | Watch | Print version | History: r1 | Backlinks | Raw View | WYSIWYG | More topic actions
Topic revision: r1 - 2015-08-13 - KatharinaMueller
 
    • Cern Search Icon Cern Search
    • TWiki Search Icon TWiki Search
    • Google Search Icon Google Search

    LHCb All webs login

This site is powered by the TWiki collaboration platform Powered by PerlCopyright & 2008-2019 by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding TWiki? Send feedback