Abstract
Assuming dark matter particles can be pair-produced at the LHC from cascade decays of heavy particles, we investigate strategies to identify the event topologies based on the kinematic information of final state visible particles. This should be the first step towards measuring the masses and spins of the new particles in the decay chains including the dark matter particle. As a concrete example, we study in detail the final states with 4 jets plus missing energy. This is a particularly challenging scenario because of large experimental smearing effects and no fundamental distinction among the 4 jets. Based on the fact that the invariant mass of particles on the same decay chain has an end point in its distribution, we define several functions which can distinguish different topologies depending on whether they exhibit the end-point structure. We show that all possible topologies (e.g., two jets on each decay chain or three jets on one chain and the other jet on the other chain, and so on) in principle can be identified from the distributions of these functions of the visible particle momenta. We also consider cases with one jet from the initial state radiation as well as off-shell decays. Our studies show that the event topologymaybeidentifiedwithasfewasseveralhundredsignaleventsafterbasiccuts. The method can be readily generalized to other event topologies. In particular, event topologies including leptons will be easier because the end points are expected to be sharper and there are more distinct invariant mass distributions from different charges.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
S. Dimopoulos and H. Georgi, Softly broken supersymmetry and SU(5), Nucl. Phys. B 193 (1981) 150 [SPIRES].
T. Appelquist, H.-C. Cheng and B.A. Dobrescu, Bounds on universal extra dimensions, Phys. Rev. D 64 (2001) 035002 [hep-ph/0012100] [SPIRES].
H.-C. Cheng, K.T. Matchev and M. Schmaltz, Radiative corrections to Kaluza-Klein masses, Phys. Rev. D 66 (2002) 036005 [hep-ph/0204342] [SPIRES].
H.-C. Cheng, K.T. Matchev and M. Schmaltz, Bosonic supersymmetry? Getting fooled at the CERN LHC, Phys. Rev. D 66 (2002) 056006 [hep-ph/0205314] [SPIRES].
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].
F.E. Paige, Determining SUSY particle masses at LHC, hep-ph/9609373 [SPIRES].
I. Hinchliffe, F.E. Paige, M.D. Shapiro, J. Soderqvist and W. Yao, Precision SUSY measurements at CERN LHC, Phys. Rev. D 55 (1997) 5520 [hep-ph/9610544] [SPIRES].
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].
B.K. Gjelsten, D.J. Miller,2 and P. Osland, Measurement of SUSY masses via cascade decays for SPS 1a, JHEP 12 (2004) 003 [hep-ph/0410303] [SPIRES].
B.K. Gjelsten, D.J. Miller, 2 and P. Osland, Measurement of the gluino mass via cascade decays for SPS 1a, JHEP 06 (2005) 015 [hep-ph/0501033] [SPIRES].
D.J. Miller,2, P. Osland and A.R. Raklev, Invariant mass distributions in cascade decays, JHEP 03 (2006) 034 [hep-ph/0510356] [SPIRES].
M.M. Nojiri, K. Sakurai, Y. Shimizu and M. Takeuchi, Handling jets + missing E T channel using inclusive mT2, JHEP 10 (2008) 100 [arXiv:0808.1094] [SPIRES].
M. Burns, K.T. Matchev and M. Park, Using kinematic boundary lines for particle mass measurements and disambiguation in SUSY-like events with missing energy, JHEP 05 (2009) 094 [arXiv:0903.4371] [SPIRES].
K.T. Matchev, F. Moortgat, L. Pape and M. Park, Precise reconstruction of sparticle masses without ambiguities, JHEP 08 (2009) 104 [arXiv:0906.2417] [SPIRES].
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].
A. Barr, C. Lester and P. Stephens, m(T2): the truth behind the glamour, J. Phys. G 29 (2003) 2343 [hep-ph/0304226] [SPIRES].
C. Lester and A. Barr, MTGEN: mass scale measurements in pair-production at colliders, JHEP 12 (2007) 102 [arXiv:0708.1028] [SPIRES].
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].
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].
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].
H.-C. Cheng and Z. Han, Minimal kinematic constraints and MT2, JHEP 12 (2008) 063 [arXiv:0810.5178] [SPIRES].
M.M. Nojiri, Y. Shimizu, S. Okada and K. Kawagoe, Inclusive transverse mass analysis for squark and gluino mass determination, JHEP 06 (2008) 035 [arXiv:0802.2412] [SPIRES].
M. Burns, K. Kong, K.T. Matchev and M. Park, Using subsystem MT2 for complete mass determinations in decay chains with missing energy at hadron colliders, JHEP 03 (2009) 143 [arXiv:0810.5576] [SPIRES].
Y. Bai and Z. Han, Measuring the dark force at the LHC, Phys. Rev. Lett. 103 (2009) 051801 [arXiv:0902.0006] [SPIRES].
J. Alwall, K. Hiramatsu, M. M. Nojiri and Y. Shimizu, Novel reconstruction technique for new physics processes with initial state radiation, Phys. Rev. Lett. 103 (2009) 151802 [arXiv:0905.1201] [SPIRES].
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].
P. Konar, K. Kong, K.T. Matchev and M. Park, Dark matter particle spectroscopy at the LHC: generalizing MT2 to asymmetric event topologies, JHEP 04 (2010) 086 [arXiv:0911.4126] [SPIRES].
K. Kawagoe, M.M. Nojiri and G. Polesello, A new SUSY mass reconstruction method at the CERN LHC, Phys. Rev. D 71 (2005) 035008 [hep-ph/0410160] [SPIRES].
H.-C. Cheng, J. F. Gunion, Z. Han, G. Marandella and B. McElrath, Mass determination in SUSY-like events with missing energy, JHEP 12 (2007) 076 [arXiv:0707.0030] [SPIRES].
H.-C. Cheng, D. Engelhardt, J.F. Gunion, Z. Han and B. McElrath, Accurate mass determinations in decay chains with missing energy, Phys. Rev. Lett. 100 (2008) 252001 [arXiv:0802.4290] [SPIRES].
H.-C. Cheng, J. F. Gunion, Z. Han and B. McElrath, Accurate mass determinations in decay chains with missing energy: II, Phys. Rev. D 80 (2009) 035020 [arXiv:0905.1344] [SPIRES].
M.M. Nojiri, K. Sakurai and B.R. Webber, Reconstructing particle masses from pairs of decay chains, JHEP 06 (2010) 069 [arXiv:1005.2532] [SPIRES].
E. Izaguirre, M. Manhart and J.G. Wacker, Bigger, better, faster, more at the LHC, JHEP 12 (2010) 030 [arXiv:1003.3886] [SPIRES].
D.S.M. Alves, E. Izaguirre and J.G. Wacker, It’s on: early interpretations of ATLAS results in jets and missing energy searches, arXiv:1008.0407 [SPIRES].
J. Alwall et al., MadGraph/MadEvent v4: the new web generation, JHEP 09 (2007) 028 [arXiv:0706.2334] [SPIRES].
J. Pumplin et al., New generation of parton distributions with uncertainties from global QCD analysis, JHEP 07 (2002) 012 [hep-ph/0201195] [SPIRES].
T. Sjöstrand, S. Mrenna and P.Z. Skands, PYTHIA 6.4 physics and manual, JHEP 05 (2006) 026 [hep-ph/0603175] [SPIRES].
J.S. Conway, Pretty Good Simulation of high-energy collisions, 090401 release, http://physics.ucdavis.edu/~conway/research/software/pgs/pgs4-general.htm (2009).
D. Krohn, L. Randall and L.-T. Wang, On the feasibility and utility of ISR tagging, arXiv:1101.0810 [SPIRES].
P. Meade and M. Reece, BRIDGE: Branching ratio inquiry/ decay generated events, hep-ph/0703031 [SPIRES].
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].
H.-C. Cheng and I. Low, TeV symmetry and the little hierarchy problem, JHEP 09 (2003) 051 [hep-ph/0308199] [SPIRES].
H.-C. Cheng and I. Low, Little hierarchy, little Higgses and a little symmetry, JHEP 08 (2004) 061 [hep-ph/0405243] [SPIRES].
I. Low, T parity and the littlest Higgs, JHEP 10 (2004) 067 [hep-ph/0409025] [SPIRES].
Y. Bai and R. J. Hill, Weakly interacting stable pions, Phys. Rev. D 82 (2010) 111701 [arXiv:1005.0008] [SPIRES].
K. Agashe, D. Kim, M. Toharia and D.G.E. Walker, Distinguishing dark matter stabilization symmetries using multiple kinematic edges and cusps, Phys. Rev. D 82 (2010) 015007 [arXiv:1003.0899] [SPIRES].
T.R. Dulaney, P. Fileviez Perez and M.B. Wise, Dark matter, baryon asymmetry and spontaneous B and L breaking, Phys. Rev. D 83 (2011) 023520 [arXiv:1005.0617] [SPIRES].
B. Batell, Dark discrete gauge symmetries, Phys. Rev. D 83 (2011) 035006 [arXiv:1007.0045] [SPIRES].
L.-T. Wang and I. Yavin, Spin measurements in cascade decays at the LHC, JHEP 04 (2007) 032 [hep-ph/0605296] [SPIRES].
J. Hubisz, J. Lykken, M. Pierini and M. Spiropulu, Missing energy look-alikes with 100 pb −1 at the LHC, Phys. Rev. D 78 (2008) 075008 [arXiv:0805.2398] [SPIRES].
G. Hallenbeck, M. Perelstein, C. Spethmann, J. Thom and J. Vaughan, Model discrimination with the CMS detector: a case study, Phys. Rev. D 79 (2009) 075024 [arXiv:0812.3135] [SPIRES].
M. Blanke, D. Curtin and M. Perelstein, SUSY-Yukawa sum rule at the LHC, Phys. Rev. D 82 (2010) 035020 [arXiv:1004.5350] [SPIRES].
A. Rajaraman and F. Yu, A new method for resolving combinatorial ambiguities at hadron colliders, Phys. Lett. B 700 (2011) 126 [arXiv:1009.2751] [SPIRES].
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
Open Access This is an open access article distributed under the terms of the Creative Commons Attribution Noncommercial License (https://creativecommons.org/licenses/by-nc/2.0), which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.
About this article
Cite this article
Bai, Y., Cheng, HC. Identifying dark matter event topologies at the LHC. J. High Energ. Phys. 2011, 21 (2011). https://doi.org/10.1007/JHEP06(2011)021
Received:
Revised:
Accepted:
Published:
DOI: https://doi.org/10.1007/JHEP06(2011)021