June 2013
Monday Tuesday Wednesday Thursday Friday Saturday Sunday
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03 04 05
10AM
11AM
5PM
06
11AM
2PM
07
2PM
3PM
08 09
2PM
4PM
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24 25 26 27 28 29 30

Wed June 5th

10AM - Higgs + jets

11AM - MC uncertainties @ NLO

$ \frac{d\hat{\delta}}{dQ^2dp_{T}^2} =  \int d^2b_{T} e^{ip_{T}b_{T}} \left[\sum\limits_{ij} \hat{\delta}^{LO}_{ij}\left(\mu_R,\mu_F\right)\left(1+H(\alpha_S(\mu_R^2))\right)\delta\left(1-\frac{\tau}{z_1z_2}\right) exp\left[\int\limits_{\frac{...}{b_{T}^2}}^{\mu_{Q^2}} \frac{d\bar{\mu}^2}{\bar{\mu}^2} \left(A(\alpha_S(\bar{\mu}^2) log \frac{\mu_{Q^2}}{\bar{\mu}^2} + B(\alpha_S(\bar{\mu}^2)))\right)\right] \int \frac{dz_1}{z_1} C(z_1)f(\frac{x_1}{z_1},\mu=\frac{1}{b_{T}}) \int \frac{dz_2}{z_2} C(z_2)f(\frac{x_2}{z_2},\mu=\frac{1}{b_{T}}) \right]$

$\tau=\frac{Q^2}{s}$

three scales: $\mu_R,\ \mu_F\ \&\ \mu_{Q^2}\ (\&\ \mu_{p_T})$

5PM - BHLA accord

  1. Passing parameters
  2. Treatment of unstable PS points
  3. Merged samples & different powers of coupling constants
  4. EW
  5. Loop induced processes
  6. Helicy & colour
  7. Diagram filters & use of symmetries

Thu June 6th

11AM - Higgs + dijets

  • VBF vs. ggF:
    • VBF: fwd+bwd, calm central region
    • ggF: central activity
  • Definition of dEtaqq can become ambiguous (producing high pT central jets is easier than producing high pT fwd jets)
  • Plotting $d\sigma/dy_{12}$ seems a good idea
  • FxFx merging:
    • cuts1: just requiring 2 jets --> limited influence from merging scale
    • cuts2: requiring 2 VBF jets --> big influence from merging scale

2PM - HepData/HepMC

HepMC
  • GenVertex::id() (--> currently defined but not allocated to something: nice for backward compatibility)

  • Base level:
    • 0. undefined / MC shit
    • 1. "signal" pr\ocess (ME) - hardest scatter - ...
    • 2. secondary scatters (partonic)
    • 3. hard decay (t,W,H, ...) - basically EW, but also hard SUSY decays, ...
    • 4. shower
    • 5. hadronisation (things coming out = primary hadrons in FS)
    • 6. hadron decays / tau decays
    • 10-99: generator specific codes
  • reweighting ~ status 1

  • weights should be named (consider e.g. MUF*2, MUR/2, ...: self-explanatory (OR MUFUP_MURDOWN)); in a vector. matrix is too much and not BWcompat.
  • naming: stick to 5 digit unique PDF naming, + index for variations
  • bottomline: it's a string, delimiter between weights = space

  • LHE discussion for Mon 2013-06-10 morning.

HepData

  • add no histogram data (0D) (e.g. cross sections w/o artificial $\delta,\eta$)
    • correlation/error matrices
    • +/- excursions for each systematic
  • auto-entry, formatting (previous discussion done --> don't want anonymous upload --> physics commitee responsibility: limited number of editors)
  • Export/import to Rivet
    • automatic "CMS data 2012" instead of "data" in plots (take from HepData)
    • automatic title if title is known instead of dxx_xxx_yxx
    • MC name/version (take from HepMC)
  • Plotting?
  • addition of background samples (e.g. complicated detector influences, not just physics)
  • search facility upgrade
    • talk to experimentalists
    • get a new manager
    • link to Rivet analyses
    • keywords

Fri June 7th

2PM - Jet substructure & PU

  • FastJet studies (G. Soyez)
    • Subtracting, areas, ...
    • W & t
  • Framework see TWiki
  • FastJet tutorial Sun June 9th, 2PM

3PM - Computing

  • aim: HEP theory
  • white paper: The computing needs of the theoretical high energy physics at the Energy Frontier
  • NERSC dedicated CPU hours: try your codes here
  • big efficiency gain for cosmology / lattice QCD

Sun June 9th

2PM - FastJet tutorial

Currently version 3.0.4 + seperate core version released Basic rules
  • clustering algorithm: anti-kt, cambridge, ...
  • all additional stuff goes into fastjet as plugins
    • e.g. ATLAS, CMS, CDF, Jade, SisCone, ... stuff
    • inlcude usually fastjet::SISConePlugin newobj(radius, threshold), then construct definition from that
  • pileup: pileup goes with jet areas --> how-to:
    • AreaDfinition: how does fastjet calculate area (cfr. doxygen)
      • e.g. active_area, but even better active_area_explicit_ghosts (if you don't keep the ghosts you loose info about the subjects)
      • if you're really bothered by ghosts, you can later on get rid of them
      • GhostedAreaSpec: basically just define the rapidity ranges etc.
    • ClusterSequenceArea: just clustering, but now with area. You still put the particles, the jet definition and now also the area definition.
    • GhostedAreaSpec
Specific to FastJet3
  • PseudoJets, after the clustering, retain the info of how they have been clustered: constituents()
  • Jets can be more the jets
  • Applying cuts: use Selectors
    • a whole bunch of selectors is predefined
    • they can be combined using logical operators
    • either use the pass() function or apply the selection to the full set and get a subset
  • PileUp --> one has to estimate the background
    • simple definition for median (for rho estimation) --> easy estimate
    • more computing efficient with GridMedian than with JetMedian
  • UserDefined functions
    • delicate part = defining result()

4PM - LHeC

Issues:
  • $u_{v}$ and $d_{v}$
    • what at $x < 10^{-2}$
    • what at $x > 0.6, 0.7$
  • $\bar{u}, \bar{d}, \bar{u}-\bar{d}$
    • $F_{2}$ = $4(u+\bar{u}) + (d+\bar{d})$
    • hi $Q^2$, CC$^{\pm}$
    • $F_{2} = (u+\bar{u}) + (d+\bar{d})$ ~ en-->eX
  • s: $ W^{\pm},Z$ at Hera, $s/\bar{d} = 1$
  • c: Silicon detectors and hi precision needed
  • b, t, b/t

  • saturation at low-x
  • non-linear gg
  • hadronization: $xg ~ A^{1/3}$
  • --> measure small $\alpha_S$, small x ($< 10^{-4}$), (ep,eA)

  • xg at high-x

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Topic revision: r6 - 2013-06-09 - SaraAlderweireldt
 
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