The stransverse mass, M T2, in special cases

Article

Abstract

This document describes some special cases in which the stransverse mass, M T2, may be calculated by non-iterative algorithms. The most notable special case is that in which the visible particles and the hypothesised invisible particles are massless — a situation relevant to its current usage in the Large Hadron Collider as a discovery variable, and a situation for which no analytic answer was previously known. We also derive an expression for M T2 in another set of new (though arguably less interesting) special cases in which the missing transverse momentum must point parallel or anti parallel to the visible momentum sum. In addition, we find new derivations for already known M T2 solutions in a manner that maintains manifest contralinear boost invariance throughout, providing new insights into old results. Along the way, we stumble across some unexpected results and make conjectures relating to geometric forms of M eff and H T and their relationship to M T2.

Keywords

Supersymmetry Phenomenology 

References

  1. [1]
    C.G. Lester and D.J. Summers, Measuring masses of semiinvisibly decaying particles pair produced at hadron colliders, Phys. Lett. B 463 (1999) 99 [hep-ph/9906349] [SPIRES].ADSGoogle Scholar
  2. [2]
    A. Barr, C. Lester and P. Stephens, m T2 : the truth behind the glamour, J. Phys. G 29 (2003) 2343 [hep-ph/0304226] [SPIRES].ADSGoogle Scholar
  3. [3]
    C. Lester and A. Barr, M TGen : mass scale measurements in pair-production at colliders, JHEP 12 (2007) 102 [arXiv:0708.1028] [SPIRES].ADSCrossRefGoogle Scholar
  4. [4]
    W.S. Cho, J.E. Kim and J.-H. Kim, Amplification of endpoint structure for new particle mass measurement at the LHC, Phys. Rev. D 81 (2010) 095010 [arXiv:0912.2354] [SPIRES].ADSGoogle Scholar
  5. [5]
    H.-C. Cheng and Z. Han, Minimal kinematic constraints and M T2, JHEP 12 (2008) 063 [arXiv:0810.5178] [SPIRES].ADSCrossRefGoogle Scholar
  6. [6]
    D.R. Tovey, On measuring the masses of pair-produced semi-invisibly decaying particles at hadron colliders, JHEP 04 (2008) 034 [arXiv:0802.2879] [SPIRES].ADSCrossRefGoogle Scholar
  7. [7]
    A.J. Barr and C. Gwenlan, The race for supersymmetry: using M T2 for discovery, Phys. Rev. D 80 (2009) 074007 [arXiv:0907.2713] [SPIRES].ADSGoogle Scholar
  8. [8]
    A.J. Barr, C. Gwenlan, C.G. Lester and C.J.S. Young, A comment on ‘Amplification of endpoint structure for new particle mass measurement at the LHC’, arXiv:1006.2568 [SPIRES].
  9. [9]
    ATLAS collaboration, Early supersymmetry searches in channels with jets and missing transverse momentum with the ATLAS detector, Technical Report, ATLAS-COM-CONF-2010-066, CERN, Geneva Switzerland (2010).Google Scholar
  10. [10]
    ATLAS collaboration, J.B.G. da Costa et al., Search for squarks and gluinos using final states with jets and missing transverse momentum with the ATLAS detector in \( \sqrt {s} = 7 \) TeV proton-proton collisions, arXiv:1102.5290 [SPIRES].
  11. [11]
    W.S. Cho, K. Choi, Y.G. Kim and C.B. Park, Measuring the top quark mass with m T2 at the LHC, Phys. Rev. D 78 (2008) 034019 [arXiv:0804.2185] [SPIRES].ADSGoogle Scholar
  12. [12]
    CDF collaboration, T. Aaltonen et al., Top quark mass measurement using m T2 in the dilepton channel at CDF, Phys. Rev. D 81 (2010) 031102 [arXiv:0911.2956] [SPIRES].ADSGoogle Scholar
  13. [13]
    D.R. Tovey, Measuring the SUSY mass scale at the LHC, Phys. Lett. B 498 (2001) 1 [hep-ph/0006276] [SPIRES].ADSGoogle Scholar
  14. [14]
    W.S. Cho, K. Choi, Y.G. Kim and C.B. Park, Measuring superparticle masses at hadron collider using the transverse mass kink, JHEP 02 (2008) 035 [arXiv:0711.4526] [SPIRES].ADSCrossRefGoogle Scholar
  15. [15]
    A.J. Barr and C.G. Lester, A review of the mass measurement techniques proposed for the Large Hadron Collider, J. Phys. G 37 (2010) 123001 [arXiv:1004.2732] [SPIRES].ADSGoogle Scholar
  16. [16]
    UA1 collaboration, G. Arnison et al., Experimental observation of isolated large transverse energy electrons with associated missing energy at \( \sqrt {s} = 540 \) GeV, Phys. Lett. B 122 (1983) 103 [SPIRES].ADSGoogle Scholar
  17. [17]
    B.C. Allanach, C.G. Lester, M.A. Parker and B.R. Webber, Measuring sparticle masses in non-universal string inspired models at the LHC, JHEP 09 (2000) 004 [hep-ph/0007009] [SPIRES].ADSCrossRefGoogle Scholar
  18. [18]
    A.J. Barr, C.G. Lester, M.A. Parker, B.C. Allanach and P. Richardson, Discovering anomaly-mediated supersymmetry at the LHC, JHEP 03 (2003) 045 [hep-ph/0208214] [SPIRES].ADSCrossRefGoogle Scholar
  19. [19]
    W.S. Cho, K. Choi, Y.G. Kim and C.B. Park, Gluino stransverse mass, Phys. Rev. Lett. 100 (2008) 171801 [arXiv:0709.0288] [SPIRES].ADSCrossRefGoogle Scholar
  20. [20]
    B. Gripaios, Transverse observables and mass determination at hadron colliders, JHEP 02 (2008) 053 [arXiv:0709.2740] [SPIRES].ADSCrossRefGoogle Scholar
  21. [21]
    A.J. Barr, B. Gripaios and C.G. Lester, Weighing wimps with kinks at colliders: invisible particle mass measurements from endpoints, JHEP 02 (2008) 014 [arXiv:0711.4008] [SPIRES].ADSCrossRefGoogle Scholar
  22. [22]
    G.G. Ross and M. Serna, Mass determination of new states at hadron colliders, Phys. Lett. B 665 (2008) 212 [arXiv:0712.0943] [SPIRES].ADSGoogle Scholar
  23. [23]
    M.M. Nojiri, G. Polesello and D.R. Tovey, A hybrid method for determining SUSY particle masses at the LHC with fully identified cascade decays, JHEP 05 (2008) 014 [arXiv:0712.2718] [SPIRES].ADSCrossRefGoogle Scholar
  24. [24]
    M. Serna, A short comparison between m T2 and m CT, JHEP 06 (2008) 004 [arXiv:0804.3344] [SPIRES].ADSCrossRefGoogle Scholar
  25. [25]
    A.J. Barr, G.G. Ross and M. Serna, The precision determination of invisible-particle masses at the LHC, Phys. Rev. D 78 (2008) 056006 [arXiv:0806.3224] [SPIRES].ADSGoogle Scholar
  26. [26]
    W.S. Cho, K. Choi, Y.G. Kim and C.B. Park, M T2 -assisted on-shell reconstruction of missing momenta and its application to spin measurement at the LHC, Phys. Rev. D 79 (2009) 031701 [arXiv:0810.4853] [SPIRES].ADSGoogle Scholar
  27. [27]
    M. Burns, K. Kong, K.T. Matchev and M. Park, Using subsystem m T2 for complete mass determinations in decay chains with missing energy at hadron colliders, JHEP 03 (2009) 143 [arXiv:0810.5576] [SPIRES].ADSCrossRefGoogle Scholar
  28. [28]
    A.J. Barr, A. Pinder and M. Serna, Precision determination of invisible-particle masses at the CERN LHC: II, Phys. Rev. D 79 (2009) 074005 [arXiv:0811.2138] [SPIRES].ADSGoogle Scholar
  29. [29]
    A.J. Barr, B. Gripaios and C.G. Lester, Measuring the Higgs boson mass in dileptonic W-boson decays at hadron colliders, JHEP 07 (2009) 072 [arXiv:0902.4864] [SPIRES].ADSCrossRefGoogle Scholar
  30. [30]
    A.J. Barr, B. Gripaios and C.G. Lester, Transverse masses and kinematic constraints: from the boundary to the crease, JHEP 11 (2009) 096 [arXiv:0908.3779] [SPIRES].ADSCrossRefGoogle Scholar
  31. [31]
    G. Polesello and D.R. Tovey, Supersymmetric particle mass measurement with the boost-corrected contransverse mass, JHEP 03 (2010) 030 [arXiv:0910.0174] [SPIRES].ADSCrossRefGoogle Scholar
  32. [32]
    I.-W. Kim, Algebraic singularity method for mass measurement with missing energy, Phys. Rev. Lett. 104 (2010) 081601 [arXiv:0910.1149] [SPIRES].ADSCrossRefGoogle Scholar
  33. [33]
    P. Konar, K. Kong, K.T. Matchev and M. Park, Superpartner mass measurement technique using 1D orthogonal decompositions of the Cambridge transverse mass variable M T2, Phys. Rev. Lett. 105 (2010) 051802 [arXiv:0910.3679] [SPIRES].ADSCrossRefGoogle Scholar
  34. [34]
    P. Konar, K. Kong, K.T. Matchev and M. Park, Dark matter particle spectroscopy at the LHC: generalizing m T2 to asymmetric event topologies, JHEP 04 (2010) 086 [arXiv:0911.4126] [SPIRES].ADSCrossRefGoogle Scholar
  35. [35]
    L. Randall and D. Tucker-Smith, Dijet searches for supersymmetry at the LHC, Phys. Rev. Lett. 101 (2008) 221803 [arXiv:0806.1049] [SPIRES].ADSCrossRefGoogle Scholar
  36. [36]
    A.J. Barr and C.G. Lester, Oxbridge stransverse mass library, http://www.hep.phy.cam.ac.uk/∼lester/mt2/index.html.
  37. [37]
    H.-C. Cheng and Z. Han, UCD stransverse mass library, http://particle.physics.ucdavis.edu/hefti/projects/doku.php?id=wimpmass.

Copyright information

© SISSA, Trieste, Italy 2011

Authors and Affiliations

  1. 1.University of Cambridge, Department of Physics, Cavendish LaboratoryCambridgeU.K.

Personalised recommendations