Recent Changes

Tuesday, May 31

  1. page Exotica Session edited ... {TracklessJetsWithSubstructure.png} Experimentalists would like to have a benchmark for this…
    ...
    {TracklessJetsWithSubstructure.png}
    Experimentalists would like to have a benchmark for this.
    Bloc 5: Long-lived Particles
    {LLP_summary_Shuve.pdf}

    Bloc 6: Collimated Objects / Hadronic Resonances
    Goals:
    (view changes)
    3:28 pm
  2. 3:26 pm

Thursday, May 26

  1. page Exotica Session edited ... Second trigger session: what can we do with FTK? Added value of a track trigger: * • for…
    ...
    Second trigger session: what can we do with FTK?
    Added value of a track trigger:
    * for scouting:
    ...
    have MET
    *

    for offline:
    Object improvements:
    * online MET
    *

    online pileup rejection
    *

    better online jet resolution
    *

    isolated tracks:
    ...
    isolated tracks?
    *

    could improve lepton/photon identification
    *

    displacement information
    Possible use cases for FTK:
    * Z+gamma, through a scalar
    *

    H-tautau, H-bb (VBF)
    *

    H ->
    ...
    is prohibitive
    *

    h/H->AA (<
    ...
    to muons
    *

    VBF + trackless jets
    *

    jet +
    ...
    resonant X
    *

    jet +
    ...
    pT track
    *

    VBF +
    but also cascade of chi2 chi1 radiating photons (edge)
    Third trigger session: triggering on clutter
    Theoretical motivation: see N. Craig's talk
    What is clutter? Hard process (annihilation) + soft process (spindown).
    * Expecting a
    ...
    soft objects.
    * how

    • How
    does this
    ...
    event”: http://arxiv.org/abs/0810.3948
    *

    Natural place
    ...
    bumphunt again
    *

    Equivalent to:
    ...
    a little
    *

    Crucial to
    Theory question: do we have models for this kind of searches? Once we have a model we start benchmarking searches and seeing if current triggers are sufficient (depends on how soft things are, it would be good to find a limiting case).
    Fourth trigger session: triggering on substructure
    (view changes)
    6:43 am
  2. page Exotica Session edited ... CMS (2015 but possibly obsolete): http://indico.ific.uv.es/indico/getFile.py/access?contribId=…
    ...
    CMS (2015 but possibly obsolete): http://indico.ific.uv.es/indico/getFile.py/access?contribId=175&sessionId=29&resId=1&materialId=slides&confId=2025
    Plenary topics:
    Motivation- Motivation for looking
    ...
    for this partpart:
    • DM very simplified models pointing the way
    • TLA done in ATLAS and CMS: numbers and performance
    ...
    light RPV stops (link to SUSY session) for substructure triggers, can we calculate granularity needed from first principles given this model?
    • what can you do with FTK and TLA? track information at L1. Lepton/photon separation?
    Motivation- Motivation for looking
    ...

    Points for discussiondiscussion:
    • Necessary to find further physics cases for this
    • Not much MET, jets are not hard enough, lepton is soft
    ...
    can you push down the single photon trigger?
    • electrons
    Differently- Differently timed LHC
    Topics for this part:
    • real-time analysis (mostly detector calibration)
    • unblinded monitoring analysis
    • delayed stream/data parking
    Accessoryaccessory collision experiments
    ...

    Points for discussiondiscussion:
    • what do we want to park and why?
    • blind analyses vs automatic analyses
    • LHCb turbo stream and buffering: why software (100% software) vs hardware triggers (FTK-like)
    • what other things can we do with auxiliary detectors using ATLAS as trigger
    Triggering- Triggering outside the
    Topics for this part:
    • Exotic Higgs as a use case
    • What is done in ATLAS and CMS in terms of unusual triggers for LLPs
    Points for discussiondiscussion:
    • How to motivate these searches, links between DM and composite Higgs and LLPs
    • Are anti-triggers useful (e.g. track or pixel veto for FTK, trackless jets)?
    ...
    • Higgs ExoDK, DM, Compressed Spectra good benchmarks for low-HT triggers. Are there others?
    • Triggers for boosted objects; Need? Status? Improvements?
    ...
    for long-lived paticles;particles; Optimized? Worth
    • Any places where moderate improvements in processing power could make a big difference?
    First trigger session: what are we scouting / what else can we scout?
    What- What is being
    Ideal use case: particle without known mass, produced in pairs, hidden in a large background. Can use sidebands/fit to find it.
    ...
    dedicated experimental studiesstudies.
    Jets: use cases and models
    dijets
    ...
    ATLAS: Record 1kHz, no parked data so far in 2015.
    Muons: use cases and models
    * single muons (dimuons)
    *

    CMS: invariant
    ...
    pT>3 GeV
    *

    low dimuon
    ...
    dark photons
    What

    - What
    else to
    Photons
    * standard photons:
    ...
    isn't there
    *

    photon-jets, pure
    ...
    work here.
    *

    no compelling
    [Here the session was interrupted by a whale sighting https://goo.gl/photos/DEnSe6yc4S1Wao649]
    Taus:
    * see problems
    Trigger thresholds are high for single photons and taus, but no compelling physics cases so far.
    Additional complication: need photon and tau identification with tracking -> see second session
    MET:
    * would be
    ...
    lower MET
    *

    Example: "exploding
    ...
    soft particles
    *

    however, need
    ...
    data scouting)
    *

    this may
    ...
    forward region
    *

    CMS has
    Displaced triggers:
    * CMS has
    ...
    jet triggers
    *

    ATLAS has displaced triggers
    *

    Can we
    Second trigger session: what can we do with FTK?
    Added value of a track trigger:
    (view changes)
    6:41 am

Wednesday, May 25

  1. page Exotica Session edited ... Points for discussion • what can we do that dileptons can't ◦ are are there sensible ... …
    ...
    Points for discussion
    • what can we do that dileptons can't
    ◦ areare there sensible
    ...
    without leptons?
    ◦ FCC

    FCC
    question: when
    • are you convinced by the quality of a TLA?
    • how low to go in couplings: in principle, leave no stone unturned. in practice, effort vs outcome: need more compelling cases
    ◦ lightlight RPV stops
    • what can you do with FTK and TLA? track information at L1. Lepton/photon separation?
    Motivation for looking for other scoutable things
    ...
    • Not much MET, jets are not hard enough, lepton is soft
    • what other corners can we experimentally cut?
    ◦ leptonsleptons - isolation,
    ▪ what are the motivations to do this? multilepton?
    • what can we do with muons?
    ◦ L1_MU15/20,L1_MU15/20, impose FTK,
    • photons
    ◦ whatwhat are the
    ...
    with this
    ◦ can

    can
    you push
    • electrons
    Differently timed LHC analyses
    ...
    Sociological/difficulty issue: these searches have to be very well motivated, as those require dedicated experimental studies
    Jets: use cases and models
    * dijets
    * plain:
    dijets
    plain:
    done at CMS/ATLAS
    * +

    +
    ISR
    * may

    may
    need substructure
    ...
    fat jet
    * models:
    * vector/axial

    models:
    vector/axial
    Z', but
    ...
    dilepton signatures
    * pseudoscalar

    pseudoscalar
    particle, but
    ...
    on vertex
    * single

    single
    production of
    ...
    ~100 GeV
    * paired

    paired
    dijets/4 jets
    * light

    light
    RPV stops, pair produced
    * may

    may
    need substructure
    ...
    third session
    * double

    double
    parton scattering:
    ...
    pp collision
    * triplets
    * gluino

    triplets
    gluino
    coverage gap
    CMS: Use of parked data in case there is something. The rate limitation of 1 kHz still applies, but only 300 Hz is processed right away.
    ATLAS: Record 1kHz, no parked data so far in 2015.
    (view changes)
    1:46 pm
  2. page Exotica Session edited ... • Triggers for long-lived paticles; Optimized? Worth additional effort right now? • Any place…
    ...
    • Triggers for long-lived paticles; Optimized? Worth additional effort right now?
    • Any places where moderate improvements in processing power could make a big difference?
    First tirggertrigger session: what
    What is being scouted:
    Ideal use case: particle without known mass, produced in pairs, hidden in a large background. Can use sidebands/fit to find it.
    (view changes)
    1:39 pm
  3. page Exotica Session edited ... A lot has been done but we are missing connections - should be improved. a) Improved theory i…
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    A lot has been done but we are missing connections - should be improved.
    a) Improved theory input can improve uncertainties:
    ...
    N_subjettiness variables (tau_DDT)(tau_DDT),
    https://arxiv.org/abs/1603.00027

    b) calculational tools can be used to constrain experimental uncertainties
    Example:
    (view changes)
    1:37 pm
  4. page Exotica Session edited ... Experimentalists would like to have a benchmark for this. Bloc 6: Collimated Objects / Hadron…
    ...
    Experimentalists would like to have a benchmark for this.
    Bloc 6: Collimated Objects / Hadronic Resonances
    Preliminary information:Goals:
    1) Maximize theory input to experiment
    2) SM Opportunities
    3) New Ideas for BSM searches
    1) Maximize theory input to experiment
    A lot has been done but we are missing connections - should be improved.
    a) Improved theory input can improve uncertainties:
    Example: decorrelation for N_subjettiness variables (tau_DDT)
    b) calculational tools can be used to constrain experimental uncertainties
    Example:
    Machine learning vs. groomers - soft-residual function is not currently exploited in tagging algorithms. This is information that helps machine learning algorithms performing a bit better. Should be explored.
    2) SM Opportunities
    Discussed 3 main areas where we can improve by utilizing substructure for SM measurements:
    a) precision measurements
    b) constraining systematics and improving simulations (eg parton showers, pdf's etc)
    c) extrapolating SM measurements to higher pt and applications to searches
    low-lying fruit:
    - boosted SM dibosons, ttbar
    - can gain knowledge by considering semileptonic channels
    - study the internal structure of gluon jets more: track multiplicity is used a lot but is infrared unsafe;
    number of subjets is better to look at infrared safe vars
    - q/g discrimination currently in context of searches but could have some made headway for SM information - and can be applicable to searches --> the better modeling of this in a data-driven way will improve our understanding and then fold into all sorts of measurements (and searches)in the long run
    - HF content (g-> bbar, ratios of HF/LF)
    harder-to-reach fruit:
    - interplay dsigma/dX (groomed) / dsigma/dX (ungroomed) --> access to the soft /hard separately
    - photon fragmentation (hard quark -> photon + soft quark) - a collinear effect
    3) New Ideas for BSM searches
    I) Experimental:
    - explore fancier triggers
    II) Non-SM like topologies
    e.g. Hidden Valley/Dark sector:
    a) boosted + diffuse
    b) boosted + boosted
    Some brainstorming ideas:
    - look for pair produced new particles decaying hadronically, can search for two highest-pT subjets in two different jets or subjets that have the same mass in two sides of the event
    - look for two highest pT jets in event that have some substructure and plot jet mass in a 2-D plot to see if there is evidence for two highly boosted particles with same mass (could be Ws or some other new particle); could be used in complicated events with additional leptons, ETMiss, b-tags, etc.; could look at jet mass or subjet mass
    - this sort of approach already used in CMS for VLQ top pair already -- i.e. extension of current techniques: RPV susy, Z'->Tt or ->TT (VLQ) etc
    ==> Led to idea of adopting a general application of a "catch-all approach" for massive subjets:
    - pair of large diffuse jets containing a single hard subjet each with the same mass
    - paired dijets with very high boost, see example by ATLAS hadronic search for RPV stops: http://arxiv.org/abs/1601.07453
    - also could apply to more general situation to look for different signal regions depending on number of leptons, b-tags, ETmiss, etc.
    III) Applications of Boosted leptons/taus and photons
    For lepton isolation, 3 approaches exist:
    a) "cone": transverse momentum sum relative to lepton in a fixed or shrinking jet cone
    b) "lepton subjet fraction" (goes along the hidden valley applications): lepton vs. subjet inside large-R jet, could be used in displaced vertex searches in conjunction with use of pronginess ; could be useful in searches for dilepton resonances at mass < 100 GeV in events that are busy, could not afford standard isolation in such case; here have access to clustering sequence information to find out whether lepton is associated with a subjet; this method is good for any non-jet particle (lepton or photon) isolation
    c) "specialized boosted" isolation: select in deltaR vs pT_rel(lep, jet) space

    (view changes)
    1:35 pm
  5. page Exotica Session edited ... {TracklessJetsWithSubstructure.png} Experimentalists would like to have a benchmark for this…
    ...
    {TracklessJetsWithSubstructure.png}
    Experimentalists would like to have a benchmark for this.
    Bloc 6: Collimated Objects / Hadronic Resonances
    Preliminary information:

    (view changes)
    1:31 pm

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