W path with ATLAS data

Žilina, 6.2.2015

Ivan Melo

Particles of the Standard Model

W - path

W - path

Hadrons: p, n, π, K, ...

L H C j e naj väč ším a naj z lož it ej ším vedeckým nást r oj om, aký bol kedy post avený

27 km supravodivých magnetov chladených na 1,9 Kelvina

Urýchľovače – továrne na nové častice

E = mc2

p + p → H + ...

1 GeV + 1 GeV + Ekin = 125 GeV

91 GeV91 GeV

125 GeV + ...

ATLAS detectorElmag. kalorimeter

Hadrónový kalorimeter

Dráhový detektor

Miónové detektory

pp -> Z -> e+e-

pT1

pT2

Sum of initial pT = 0 Sum of final pT = 0

Transverse momentum pT

If sum of final pT ≠ 0:1 2

3

1+2+3

Missing pT = Missing ET = ETMiss

Chýbajúca priečna hybnosť

ETMiss > 20 GeV (asi neutríno)

ETMiss < 20 GeV (nie neutríno, skôr nedokonalosť detektora)

Beta decay

W production and decay

Higgs boson production

W - path

H W+ W- e+μ- ννe+e- νν μ+μ- ννμ+e- νν

Higgs boson decay via WW channel

W decay

pp -> Z -> e+e-

e-/e+

μ-/μ+

μ-/μ+

neutríno

Missing ET = missing pT > 20 GeV

kvarky (a gluóny) vidíme ako „jety“, spŕšky hadrónov

Veľa dráh, 2 eventy naraz (pile-up)

Invariantná hmotnosť

Invariantná hmotnosť

Pozadie (background)Signál +pozadie

To access ATLAS data:username: ippogpassword: mc13Pick assigned number (1 or 2) and letter (A,B,C,....,Z)

http://www.physicsmasterclasses.org/index.php?cat=local_organisation&page=measurements

ATLAS Z-path

Hypatia

1.Download 2.Unzip it onto your Desktop 3.To start HYPATIA:

a. Navigate to the HYPATIA folder you downloaded

b. On Windows and Mac:oDouble click on“Hypatia_7.4_Masterclass.jar”

c. On Linux: Right click on “HYPATIA_for_Linux.sh” and change permissions so that it is executable. Double-click on “HYPATIA_for_Linux.sh”

http://atlas.physicsmasterclasses.org/en/zpath_data.htm

Datasets: ATLAS real pp-data from 2012 at 8 TeV

Di-leptons: ~ 20 000 events

- Di-electrons and di-muons from Z (mainly), Jpsi and Upsilon

- 2 000 fully simulated Z’ events (mass 1 TeV)

Higgs candidates: real data events corresponding to 2 fb-1

- Di-photon: 12 000 events cuts as in ATLAS publication–including converted photons

- 4-leptons: 40 events cuts as in ATLAS publication

- very little background!- almost no need to discuss ET miss!

- Evaluate your set of 50 events (e.g. 1C)- Make notes on your tally sheet (e.g. 1C)- Consult cheat list for students: http://cernmasterclass.uio.no/2014/material/cheat-sheet_en.pdf

Set pT cut at 5 – 10 GeV Check tracks and physics objects If two tracks (+- charge) point to two elmag clusters in both views – e+e- candidate If no tracks point to two elmag clusters in both views - γγ candidate If two tracks (+- charge) continue to muon chambers – μμ candidate If four charged tracks (+-+-) - μμμμ, μμee, eeee candidate Check Pixel hits >= 2 and SCT hits >= 7 to see if particles come from the same vertex In case of converted photon candidate: check invariant mass of the (+-) double track, if close to 0, it is photon converted to e+e-

- Enter candidate tracks as ee, μμ, γγ to see their invariant mass- Export invariant mass table as .txt file (File – Export invariant masses)

Analysis

OploT: http://cernmasterclass.uio.no/OPloT/index.php

Click on Student For test pick January 01 2012, any test city, group number and letter Upload your .txt file with invariant masses (Browse button)

If you need to delete a students upload, you can do this from the Administrator tab. Password:

username: adminpassword: administrator

How to submit results