A general method for model-independent measurements of particle spins, couplings and mixing angles in cascade decays with missing energy at hadron colliders

被引:53
作者
Burns, Michael [1 ]
Kong, Kyoungchul [2 ]
Matchev, Konstantin T. [1 ]
Park, Myeonghun [1 ]
机构
[1] Univ Florida, Dept Phys, Gainesville, FL 32611 USA
[2] Fermilab Natl Accelerator Lab, Dept Theoret Phys, Batavia, IL 60510 USA
来源
JOURNAL OF HIGH ENERGY PHYSICS | 2008年 / 10期
关键词
Beyond Standard Model; Supersymmetric Standard Model; Hadronic Colliders;
D O I
10.1088/1126-6708/2008/10/081
中图分类号
O412 [相对论、场论]; O572.2 [粒子物理学];
学科分类号
摘要
We outline a general strategy for measuring spins, couplings and mixing angles in the case of a heavy partner decay chain terminating in an invisible particle. We consider the common example of a heavy scalar or fermion D decaying sequentially to other heavy particles C, B and A by emitting a quark jet j and two leptons l(n)(+/-) and l(f)(-/+). We derive analytic formulas for the dilepton ({l(+)l(-)}) and the two jet-lepton ({jl(n)} and {jl(f)}) invariant mass distributions for the case of most general couplings and mixing angles of the heavy partners. We then consider various spin assignments for the heavy particles A, B, C and D, and for each case, derive the relevant functional basis for the invariant mass distributions which contains the intrinsic spin information and does not depend on the couplings and mixing angles. We propose a new method for determining the spins of the heavy partners, using the three experimentally observable distributions {l(+)l(-)}, {jl(+)} + {jl(-)} and {jl(+)} - {jl(-)}. We show that the former two only depend on a single model-dependent parameter alpha, while the latter may depend on two other parameters beta and gamma. By fitting these distributions to our set of basis functions, we are able to do a pure measurement of the spins per se. Our method is also applicable at a p (p) over bar collider such as the Tevatron, for which the previously proposed lepton charge asymmetry is identically zero and does not contain any spin information. In the process of determining the spins, we also end up with an independent measurement of the parameters alpha, beta and gamma, which represent certain combinations of the couplings and the mixing angles of the heavy partners A, B, C and D.
引用
收藏
页数:64
相关论文
共 56 条
  • [1] ABDULLINT S, HEPPH0608322
  • [2] Measuring sparticle masses in non-universal string inspired models at the LHC
    Allanach, BC
    Lester, CG
    Parker, MA
    Webber, BR
    [J]. JOURNAL OF HIGH ENERGY PHYSICS, 2000, (09): : XIII - 30
  • [3] Unravelling the sbottom spin at the CERN LHC
    Alves, Alexandre
    Eboli, Oscar
    [J]. PHYSICAL REVIEW D, 2007, 75 (11):
  • [4] It is a gluino
    Alves, Alexandre
    Eboli, Oscar
    Plehn, Tilman
    [J]. PHYSICAL REVIEW D, 2006, 74 (09):
  • [5] [Anonymous], HEPPH0510204
  • [6] Bounds on universal extra dimensions
    Appelquist, T
    Cheng, HC
    Dobrescu, BA
    [J]. PHYSICAL REVIEW D, 2001, 64 (03)
  • [7] ATHANASIOU C, HEPPH0606212
  • [8] Athanasiou C, 2006, J HIGH ENERGY PHYS
  • [9] Weak-scale phenomenology of models with gauge-mediated supersymmetry breaking
    Bagger, JA
    Matchev, KT
    Pierce, DM
    Zhang, RJ
    [J]. PHYSICAL REVIEW D, 1997, 55 (05): : 3188 - 3200
  • [10] Measuring slepton spin at the LHC
    Barr, AJ
    [J]. JOURNAL OF HIGH ENERGY PHYSICS, 2006, (02): : 042