New Physics

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15:30, QCD Room: Boosted Z / W - Analysis plan of attack
15:30, QCD Room: Boosted Z / W - Analysis plan of attack
17:00 transition zone between classical ttbar to boosted top

Revision as of 07:38, 25 June 2009


New Physics at the LHC

The New Physics part will meet at Les Houches during the period 17-26 June 2009, but people should form an idea of the studies they would like to pursue before that. All work should be completed by the end of 2009. The preference will be for studies focused on recent developments in new physics possibilities.



15:00 Auditorium: BSM with top, incl. jet structure


9:00 Auditorium: Dark matter & colliders, hidden sectors/valleys

Matt Strassler: Intro to Hidden Valleys Image:Strassler.LesHouches.pdf

David Morrissey: Dark Matter in Dark Sectors and "Lepton Jets" Image:Leshouches-dm.pdf

Jay Wacker: Composite Dark Matter, DAMA, and "Lepton Jets" Image:Wacker.LesHouches.pdf

Yuri Gershtein: D0 Results on Searches for SUSY inspired "Lepton Jets"

16:00 Library: Hidden Valley Monte Carlo Discussion

16:30 QCD room: Boosted W and Z


11:00 Auditorium: Dictionaries mapping signatures to models

14:00 Library: Long-Lived Particles

16:30 Library: spin/mass determination



9:00, Auditorium: Delphes Tutorial

11:00, Library: From signatures to models: follow-up.

11:30, QCD room: Flavour violating Higgs couplings (Kaustubh Agashe).

14:00, QCD room: Dirac gauginos and new SUSY signals (Adam Martin).

14:00, Library: Boosted W & Z

15:00, Auditorium: Dark Matter from Extra Dimensions at the LHC (Giacomo Cacciapaglia)

16:00, Library: Spins and Masses

16:30, QCD room: (CONTINUED from 14:00 meeting in Library) Pairs of boosted hadronic W/Z from decay of resonances (Kaustubh Agashe)

18:00 QCD room: Long-lived stuff (including D0 experimental techniques)


11:00, Library: Hidden Sector Benchmarks (HV and Dark Matter, for both experimental reco and analysis)

11:00, QCD room: Flavour violating Higgs couplings (Kaustubh Agashe): see references/wishlist in "Talks and Links" below.

14:00, QCD room: Use of polarized tops (Ritesh Singh).

15:00, QCD room: Four top events (Ben Gripaios).

16:00 Library: Spins and Masses


11:00, Library: Dirac gauginos, R-symmetry, and new signals of SUSY (Adam Martin).

14:00, QCD room: Flavour violating Higgs couplings (Kaustubh Agashe): see references/wishlist in "Talks and Links" below.

17:00, QCD Room: Nearby resonances and MC implementation (Aldo Deandrea)


10:00, Auditorium: Z_2 versus Z_3 dark matter (Geraldine Servant, Kaustubh Agashe, Seung Lee)

14:00, QCD room: Flavour violating Higgs couplings (Kaustubh Agashe): see references/wishlist in "Talks and Links" below.

14:30, Library: Spins and masses

15:30, QCD Room: Boosted Z / W - Analysis plan of attack

17:00 transition zone between classical ttbar to boosted top


Talks and links

BSM with top:

* [1] ATLAS note on top reconstruction with substructure
* [2] ATLAS note on very high pT b-tagging
* see also the Jet Substructure page that was started in session 1.

SUSY blind analysis project:

* [3] Webpage with description & first results.

Data Reporting:

* [4] Talk by Kyle Cranmer regarding publishing Likelihood maps for discoveries electronically using the RooStats package.

Mass Determination:

* [5] WIMPMASS code (polynomial system solver for cascade decays with 2 missing particles)
* Media:Leshouches_2009.pdf Bob McElrath's talk about polynomial methods.


  • See, for example,

for a model-INDEPENDENT study of Higgs flavor violation.

Higgs flavor-violation in (warped) extra- dimensional/composite Higgs model is discussed in same reference [estimates are given in abstract are BR (t->cH) ~ 10^(-4) and BR(H->tc) ~ 5 x 10^(-3)]

and (for more detailed numbers).

[Note that the "RADION" (scalar particle corresponding to fluctuations of size of extra dimension) also decays to tc (very similarly to Higgs): see]

  • The THEORY reference which claims LHC sensitivity of 5 x 10^(-5) for BR(t->cH) (FOR M_H < m_t) is (table 4 on p.11) (see also for more details).

Upon some discussion involving experimentalists and phenomenologists, it was found that (up to effects from detector simulations) this level of sensitivity sounds reasonable.

(A reference for a study of H->tc - for M_H > m_t - at a similar level could not be found).

  • A wish list:

(a) A detailed study of LHC sensitivity for tcH coupling FOR M_H > m_t

(i) Via Higgs DECAYS: the Higgs can be produced via gluon fusion or by WW fusion (in the latter case, we can tag forward jets).

See references and given above for 1st steps toward this goal (including some analysis of background.

And, reference studied flavor-violating Higgs decays to top in a different framework (2-Higgs doublet model), but without any analysis of background.

(ii) Another option is to use the tcH coupling to PRODUCE Higgs, for example, g c -> t H (see reference for a study of this channel, but with H->bbbar, whereas here we would like to use H->WW/ZZ since M_H > m_t).

In both (i) and (ii) above, a starting point might be to use existing studies of related channels in SM (or its extensions) which look similar (for example, g b -> t H^+ in 2-Higgs doublet models vs. g c -> t H here or single top production in SM vs. gg-> H->tc here) to see how other background was reduced.

(b) ATLAS group is undertaking a study of t->cH: can CMS be far behind?

(c) tagging charm from t-> cH (which typically dominates over t->uH), in case it is useful for rejecting some background.

(d) more precise study of LHC sensitivity for t-> cH, for example

(i) optimizing cuts to improve the sensitivity and

(ii) including intermediate M_H of ~150 GeV (say) so that H -> bb is very small and H->WW dominates (only M_H = 110, 130 GeV were studied in above references such that the dominant decay mode H->bb was used).

be within LHC reach (see reference

Interestingly, this leptonic decay is of the above size (reachable at the LHC) only for Higgs which is NOT a pseudo-Goldstone boson (PGB), whereas it is much smaller (i.e., beyond LHC reach) for PGB Higgs. Hence, this channel might provide a window into the nature of Higgs in this framework. It turns out that Htc coupling is of similar size for PGB vs. non-PGB (although the chiral structure is different for the two cases) and thus this channel might not be as suitable for distinguishing the two cases.)

Work Topics & Wish Lists

Boosted W/Z:

Theorists' wish list:

  • Efficiency & background rejection for boosted Z to ee, mumu, bb; W and Z to qq (non-bb); what is the jet mass resolution vs jet pT for merged jets from color singlet objects?
  • Can we identify something like u' -> Wu, W->e/mu nu? (MET will be aligned with lepton/jet, use collinear approx & W mass to constrain fake MET?)

Experimental results

Experimenters' wish list:

  • Exhaustive list of models producing boosted W and Z bosons (organized by other objects in the event), with x-section ranges.

Long-Lived Particles:

"If it can be short-lived, it can often also be long-lived"

Experimenter's wish list:

  • Monte Carlo generators

Spin and Mass Reconstruction:

  • With current mass methods developed for SUSY, what do you get for non-SUSY? (Tommaso)
  • Comparisons of mass methods and where they work/fail (Bob)
  • What about off-shell particles? (Juergen/Ritesh)

Dirac Gauginos:

From Signature to Model:

ttbar + n jets in the SM:

It has become clear that the ttbar + n jets (with n > 3) background to searches is large. Studying the properties of measurable quantities in anticipation of comparisons to data and validation of models is thus important.


From the information given during the registration process, the following "groups of interest" were identified:

   -Extra dimensions: Agashe, Boos, Bunichev, Cacciapaglia, Deandrea, Fichet, Fox, 
    Gopalakrishna, Grojean, Harper, Henderson, Karagoz Unel, Kraml, Lee, Llodra-Perez, 
    Mahmoudi, Moreau, Morrissey, Przysiezniak, Rosenfeld?, Servant, Singh, Wacker.
   -Technicolor & other EWSB: Agashe, Black, Bose, Boudjema, Del Debbio, Gripaios, 
    Grojean, Harper, Lane, Maravin, Martin, Reuter, Rosenfeld, Servant, Shepherd, Wacker.
   -Z': Basso, Harper, Jackson, Reuter, Singh, Shepherd.
   -BSM through top: Agashe, Boos, Boudjema, Brooijmans, Gopalakrishna, Gray, Gripaios, Grojean,   Guchait,Karagoz 
    Unel, Lee, Lessard, (Raklev), Servant, Shepherd, Singh, Tytgat, Vos, Wacker.
   -Hidden Valley: long-lived particles: Basso, Gershtein, Maravin, Morrissey , Strassler, Tomalin.
   -Hidden Valley: multiparticle production (benchmarks and backgrounds): Strassler.
   -Dark matter and colliders: Agashe, Belanger, Boudjema, Fox, Gopalakrishna, Guchait,Kraml, 
    Kribs, Lee, LLodra-Perez, Mahmoudi, Martin, Morrissey, Pukhov, Robens, Roy, Raklev, Sekmen, Shepherd, Strassler.
   -Dictionary of signatures & model-independent searches: Belyaev, Bruneliere, Das, 
    Datta, Del Debbio, Fichet, Fox, Gopalakrishna, Henderson, Kauer, Kraml, Lari, Reuter, Robens, Roy, Sekmen, 
    Shepherd, Tytgat.
   -Spin/mass determination: Boudjema, Datta, Gripaios, Lester, Mahmoudi, 
    McElrath, Reuter, Robens, Singh.
   -SUSY Pheno: Fichet, Kraml, Lari, Mahmoudi, Martin, Morrissey, Reuter, Robens, Roy, Slavich, Spira.
   -Tools: Basso, Belyaev, Boos, Bruneliere, Bunichev, Cacciapaglia, Das, Datta, 
    Del Debbio, Kraml, Mahmoudi, Przysiezniak, Pukhov, Reuter, Richardson, Semenov, Slavich, 
    Spira, Strassler.

(Before registration, we had listed some possibilities:

   - Hidden valleys (and other models with long-lived particles)
   - New physics decaying to top quarks
   - Exotic quarks
   - 4th family (mirror or sequential)
   - LHC-dark matter: LHC signals related to hints from PAMELA, ATTIC, DAMA

Furthermore, it would be interesting to further develop guidelines for follow-ups after a potential discovery: if we see X then what should we look for?)

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