Tuesday, 6 May 2014

Pheno 2014 Liveblog: Day One, Session 3

First parallel session of the conference.  I'm going to try and switch between rooms, starting in Dark Matter 1.

2:00 pm: Dark Matter and Complementarity, Alexander Wijangco

Complementarity follows from the same DM-Visible coupling relating different experimental probes.  The standard DD vs ID vs Collider probes.

For time reasons, example: use Hooper excess to motivate studies at DD/colliders (Bayesian language: to motivate/construct priors).

Using effective operators for Dirac fermion annihilating to bottom quarks.  Signal needs s-wave annihilation.  Just using different searches as applied to different effective operators for DM interactions.  This tells us that effective operators (heavy new physics) and couplings to protons in trouble.

Consider instead dark mediators.  Essentially annihilation to 4 or 6 b quarks.  Can work with all constraints, DM now heavier.

2:15 pm: New Directions in Dark-Matter Complementarity: Inelastic Scattering and Constraints on Dark-Sector Instability, Brooks Thomas

Multi-DM theories: in particular, the new direction of DM decay to a dark sector particle + SM.  Additionally, such theories have inelastic DM scattering at DD experiments.

Again, an EFT approach with (two) Dirac fermion DM.  A good approximation for direct detection.  Assume that single non-diagonal operator dominates to make the multi-component and dark decay effects relevant.

Kinematics important for up- vs down-scattering.

For decays, small Δm means only real decay is DM to DM + γγ.

Shown that:
  1. Regions exist unprobed by current searches, unlikely to ever be;
  2. Regions exist where multiple searches could see signals.
2:30 pm: Origin of the Icecube TeV-PeV Neutrino Events, Jordi Salvado

28 high energy events measured between May 2010 and May 2012.  7 measured with tracks (1 degree  resolution) and 21 with cascades (10 degree resolution).  Consistent with democratic neutrino flavour (expected from oscillations from distant source).  Sources point (with small statistics) towards galactic centre (by eye).

Icecube is more sensitive at high energies, so lack of signals > PeV might be relevant.

No correlations in position/time with GRB/AGN/similar.  Do we need NP to generate these neutrinos?  We would expect them to come from the galactic centre.  So try to do statistical analysis to test this.  Looks like the answer is no.

2:45 pm: Probing Radiative Neutrino Mass Generation through Monotop Production, Alejandro de la Puente

Looks like a fermion-partner type model, with the right-handed neutrino serving as DM.

Z2 symmetry forbids Dirac neutrino masses; Majorana masses arise at three loops.  Requires additional scalars, triplets under both colour and SU(2)L.

DM density requires largeish coupling to quarks, to get relic density without being killed by monojets.  Follows then that monotop searches are a natural direction to go.  Current data is insufficient.  14 TeV can still hope to say something useful, though can not rule model out completely in 300 inverse fb.

3:00 pm: Chasing Light Vector-Like Leptons from the SM Higgs to ZZ* Search, Seodong Shin

Motivated, of course. by Higgs decay to γγ which is still slightly large at ATLAS.  Also affect Higgs mass, running of couplings and possibly DM (if neutrino state).  If mix with SM leptons, can explain , of course.

Given this, how can Higgs golden channel constrain this?  Coming from a different topology; not 1 > 2, each 2 decaying, but 1 > 2, followed by 1 > 3.  Current constraints at ~ 120 GeV.

3:15 pm: Higgs Decays in Gauge Extensions of the Standard Model, Bithika Jain

Consider general [SU2 x U1]^n NLSM with link fields.  Typical simple model for extra dimensions/strong sectors.  Results in some general three-gauge boson couplings that can then contribute to Higgs loops.

Point seems to be to construct tools to compute a general example of such model, illustrated with a specific example (n = 4).

3:30 pm: A New Method for the Spin Determination of Dark Matter, Daniel Salmon

DM spin is a long-standing problem due to the missing energy.  As such we do not know the location of the parent rest frame.  Work is done at lepton collider, where at least it is possible to know the rest frame of the initial state.

Idea seems to be that once you know that parent/daughter masses, can analytically solve for the unknown kinematics.  Then you get distributions that can be classified into different groups.  However, "most likely" possibility (either DM or parent is scalar) give same distributions (I think).

3:45 pm: Better Mass Measurements Using Many-body Phase Space in Cascade Decay, Jianghao Yu

Another long-standing DM/SUSY problem.  In particular, we need to reconstruct the masses of multiple particles simultaneously.  Two-body decays and 3-body decays are well known, and realistic models have decay chains that factorise as successive 2- and 3-body final states.  So do we need to do any more?

The traditional approach is just to do this, but suffers heavily from low statistics.  So consider >3-body final states to track all phase space correlations.  In particular, construct multi-dimensional kinematic distributions, not just one-dimensional ones.

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