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2017:groups:np:qfvlhc

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Squark decays beyond MFV at LHC

People: Priscilla Pani, Giacomo Polesello, Amit Chakraborty, Björn Herrmann, Benjamin Fuks, Mihoko Nojiri, Abishek Iyer

Idea

  • Investigate QFV signature: pp → t j ETmiss
  • Start by implementing a simplified model, then try to move on to more realistic case.

Setup

We start by investigating a simplified model setup as follows.

The two-squark system is parametrized with the parameters:

  • mSt (stop mass parameter),
  • mSc (scharm mass parameter),
  • mStc (mixing parameter).

After diagonalisation, the physical parameters are:

  • mSq1 (lighter squark),
  • mSq2 (heavier squark),
  • thSq (mixing angle),

such that Sq1 = cos(thSq)*St + sin(thSq)*Sc.

Moreover, we consider:

  • mN1 (neutralino mass),
  • mGl (gluino mass).

Put model files here…

Working plan

1. Compute diagonal production cross-sections (at LO): function of mSq1 and mSq2, but independent of thSq.

2. Compute non-diagonal production cross-sections (at LO): function of mSq1, mSq2, and thSq. Evaluate, e.g., for thSq=(0, pi/4, pi/2) and mGl=3 TeV, and check importance w.r.t. diagonal production.

3. Compute branching ratios of Sq1 and Sq2 into t+N1 and into c+N1: function of mSq1, mSq2, thSq, mN1.

4. From the above, deduce cross-sections pp → t t ETmiss, pp → c c ETmiss, pp → t c ETmiss: functions of mSq1, mSq2, thSq, mN1. Make sure to seperate contributions from different subchannels, since this information is necessary to determine the experimental acceptance!

5. Compute the above signal cross-sections in the full model (i.e. with 4×4 mixing) and use the obtained acceptances to deduce the limits.

References

  • “Impact of squark generation mixing on the search for squarks decaying into fermions at LHC”, (arXiv)
  • “General squark flavour mixing: constraints, phenomenology and benchmarks” (arXiv)
  • “Gluino Meets Flavored Naturalness” (arXiv)
2017/groups/np/qfvlhc.1497886736.txt.gz · Last modified: 2017/06/19 17:38 by bjoern.herrmann