1 / 8

Exploring Muon pT Distribution for Z to Z’ Extrapolation in High-Energy Physics

This study investigates the pT distribution of muons from Z decay to extrapolate potential signatures of a Z’ boson in the high-energy regime (1-2 TeV). By employing a tag-probe method, we include both high pT (>30 GeV/c) and low pT (<30 GeV/c) muon tracks using loose selection criteria. The analysis utilizes data from ~250K events with MuidCombined muons, focusing on efficiency calculations with stringent cuts to suppress background. The goal is to understand the efficiency behavior at various pT ranges and improve systematic uncertainties in tag-probe fits.

tejana
Télécharger la présentation

Exploring Muon pT Distribution for Z to Z’ Extrapolation in High-Energy Physics

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. rec. muon pT (GeV/c) Tag-probe method:Fitting Z →μ+μ-mass peaks • Motivation: 1. Want to use long pT tail of muon from Z to extrapolate to high pT regime where Z’ might live (1TeV - 2TeV) 2. Also include low pT muons (< 30 GeV/c) • need loose selection criteria to allow for softer muons • so far no hard cuts or isolation on ID probe track • CBNT level analysis, using MuidCombined muons so far • Release 12 sample Pythia Z →μ+μ- (using ~250K events corresponding to ~150 pb-1) 2. 1.

  2. N: all ID tracks example: eff(2.25 < η < 2.50) = n/N tag muon pT > 30 GeV/c n: probe found in MS

  3. dRcut combined muon truth muon passes truth muon fails eff crosscheck with MCtruth • compare tag-probe fits with truth • would like to count only muons which came from Z • # true muons > 1 (within |η|<2.7) • Hard cut on truth muons: pT > 30 GeV/c • truth matching to reconstructed track: • dR = (dη2 + dΦ2)½ < 0.1 • might need to update the matching to include other parameters (ie: pT) • use vertex • eff is a function of truth pT or η, where in tag-probe, eff (ID track pT or η)

  4. N:(mu + any ID track) dimu mass (GeV/c2) n:(mu + mu ID track) dimu mass (GeV/c2) eff( probe η ) Cuts: • tag: pT > 30 GeV/c • probe: pT > 8 GeV/c (errors scaled to correspond to 100 pb-1) probe muon η - Bias may come from MCtruth method not corresponding exactly to tag-probe? - in mu+mu plot: asymmetry in histo from background or signal?

  5. N:(mu + any ID track) dimu mass (GeV/c2) n:(mu + mu ID track) dimu mass (GeV/c2) eff( probe η ) –> cleaned up Cuts: • tag: pT > 30 GeV/c • probe: pT > 30 GeV/c probe muon η • set background = 0 • (totally suppressed by pT cut) • - still no isolation cuts

  6. bin: 0 1 2 3 4 5 6 7 8 9 10 eff( probe pT ) cuts: • |η| < 2.5 • Virtually no bckgnd after 30 GeV/c Besides background, there is an asymmetric tail due to pT binning …need an asymmetric fit 1.2% uncertainty in tag-probe: 2.4% 4.0% 2.0% (errors scaled to correspond to 100 pb-1) bin4 pT: 50->58 GeV/c bin0 pT: 3->30 GeV/c bin1 pT: 30->38 GeV/c N N N dimu mass (GeV/c2) dimu mass (GeV/c2) dimu mass (GeV/c2) n n n

  7. Z (91 GeV): rec. muon pT (GeV/c) Z’ (1 TeV): (pT = 15 – 60 GeV) (pT = 60 – 600 GeV) rec. muon pT (GeV/c) (pT = 600 – 1600 GeV) MCtruth efficiency Z to Z’ • Quick check (on release 11) • How does the eff scale at higher energies? • Look at MCtruth eff in a wide bin from Z, Z’ • |η| < 2.5 …some evidence of eff having a pT dependence (but also could be due to different η distributions)

  8. to do list: • better fit? • signal and background separation • use asymmetric fit function rather than BW? • is asymmetry coming from signal or resolution? • examine the shape of the diMu background dist. • look at new release 12 Z’ samples • examine pT dependence of eff for Z’ analysis cuts (ie: isolation cuts) • move to AOD • go further out in pT…beyond 200 GeV/c thanks!

More Related