SPICE: Simulation Package for
Including Flavor in Collider Events
Felix YuUniversity of California, Irvine
G. Engelhard, J.L. Feng, I. Galon, D. Sanford, FY, arXiv: 0904:1415v1 [hep-ph]
J.L. Feng, I. Galon, D. Sanford, Y. Shadmi, FY, arXiv: 0904.1416v1 [hep-ph]
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The Standard Model Flavor Problem and Beyond
• Theorist’s motivation for flavor studies– SM flavor problem– If new physics is seen at the LHC, have to also
address new physics flavor puzzle– Can create and test new models which explain
some of these outstanding issues
• Experimentalist’s motivation– Minimal flavor-violating models are simple, but
new physics is not necessarily simple– Flavor-violating new physics could be easier to
see than flavor-conserving version
• Enter SPICE
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What is SPICE?
• SPICE is a simulation tool for lepton flavor studies– takes a flavor-conserving minimal SUSY model– adds flavor-violating parameters– outputs the SUSY spectrum and lepton flavor-
general branching ratios– relies upon SOFTSUSY and SUSYHIT
• Output (in Herwig, SLHA, and SLHA2 formats) is ready for use in your favorite Monte Carlo event generator
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mSUGRA
mGMSB “Spine”
mAMSB
What is SPICE?
Flavor-violating
parameters
(U(1) charges or
user-defined)
SPICE
SUSY spectrum and flavor-general decay widths
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Yet Another Simulation Package?
• Most all simulation packages (ISAJET, CompHEP, MadGraph) typically adopt MSSM and other minimal SUSY models as standard– Currently, adopting a non-minimal model requires
customization via LanHEP (for CompHEP) or FeynRules (for MadGraph)
• Our program allows for an explanation of flavor observables via U(1) flavor models
Feng, Lester, Nir, Shadmi (2007)
Froggatt, Nielsen, Ibanez, Ross, Nir, Seiberg, Anderson, Raby, Dimopoulos, Hall, Starkman…
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LHC Applications
• Could generically get lots of new low-energy signatures which can be clean and easily measurable– The nature of the NLSP and the light SUSY
particle decays dictates the difficulties and efficiencies of reconstruction
• Will now focus on models with slepton NLSPs– Gravitino is LSP, slepton NLSP escapes the
detector– Reasonable, easier than bino NLSP case, and
interesting on its own
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FC Three-Body Decay Modes in Models with Slepton NLSPs
• Previous work on three-body slepton decays was restricted to flavor-conserving models– Studies using flavor-conserving models ensure that
taus are ubiquitous
-
R
~–
1~-
~ R
~–
-
1~+
~
Charge-preserving Charge-flipping
Ambrosanio, Kribs, Martin (1997)
West Coast LHC Theory Meeting, April 17, 2009
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FV Three-Body Decay Modes in Models with Slepton NLSPs
• With flavor violation, lots of modes open up and many different lepton combinations are possible
Three-Body Modes Included in SPICE
Charge-preserving Charge-flipping
~–
-
~
-
~+
~–
-
~
-
~+
-
~–
~
+
~–
-
~–
~
+
~–
-
~–
H ,q
~–
+,q– -
~–
Z ,q~–
+,q– –
Feng, Galon, Sanford, Shadmi, FY (2009)
West Coast LHC Theory Meeting, April 17, 2009
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Cascade Decays
q~02
~01
~
q
4-6
~
2-3
~
1
~
G~(
)• An optimistic scenario for SUSY with a slepton
NLSP– Lots of leptons, and especially interesting with flavor
violation
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Reconstructing Decay Chain
• Truth masses (in GeV) for
a different FV slepton NLSP
model
• Can we see flavor-violation
at early stages of reconstruction?
– reconstruction of slepton
NLSP should be straightforward0.403~2.225~8.344
~6.306
~8.283
~9.169
~9.139
~9.134
~
02
01
6
5
4
3
2
1
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Flavor Information in the Bino Reconstruction?
• Invariant mass of 1e and 1after cut on
pT
Preliminary, Work in Progress
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Flavor Information in the Bino Reconstruction?
• Zooming in on the hard-pT cut plots
Preliminary, Work in Progress
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Questions to Consider
• Can we distinguish ~5-10 GeV mass splittings?
• Can we measure mixings with early LHC data?
• What are the easy signatures of flavor-violating models? – Do not necessarily have lots of taus, for
example
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Conclusions
• SPICE is a timely, useful application to help with lepton flavor studies– completely general
• Download it from
http://hep.ps.uci.edu/~spice• Future work
– inclusion of squark flavor mixing– calculation of low-energy constraints
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Flavor-Conserving Bino NLSP Model
• Light higgs 109.4505• Heavy, Pseudoscalar Higgs 494.3590• Charged Higgs 500.7804• Left d, s 837.4747• Left u, c 830.4740• Light b 782.0099• Light t 686.9815• Right d, s 793.4322• Right u, c 796.2180• Heavy b 794.6305• Heavy t 810.8433
• Gluino 780.7523
• Neut1 131.0896
• Neut2 246.6087
• Neut3 415.8810
• Neut4 436.3886
•Slep1 147.4091
•Slep2 152.9753
•Slep3 152.9897
•Slep4 287.0535
•Slep5 287.1140
•Slep6 287.7173
•Snu1 275.3281
•Snu2 275.7312
•Snu3 275.7325
•Char1 246.7770
•Char2 438.3474
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Flavor-Violating Bino NLSP Model
• Light higgs 109.4327• Heavy, Pseudoscalar Higgs 495.5477• Charged Higgs 501.9262• Left d, s 837.3721• Left u, c 830.3876• Light b 781.8474• Light t 687.4050• Right d, s 793.1978• Right u, c 796.6701• Heavy b 794.4472• Heavy t 810.8499
• Gluino 780.7551
• Neut1 131.2707
• Neut2 246.7691
• Neut3 416.5810
• Neut4 437.0140
•Slep1 191.0296
•Slep2 197.7382
•Slep3 203.8811
•Slep4 267.1493
•Slep5 289.6940
•Slep6 309.8771
•Snu1 253.7412
•Snu2 277.8040
•Snu3 299.4458
•Char1 246.9317
•Char2 438.9892
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Flavor-Conserving Slepton NLSP Model
• Light higgs 111.7324• Heavy, Pseudoscalar Higgs 567.0095• Charged Higgs 573.7404• Left d, s 1112.511• Left u, c 1104.877• Light b 1058.835• Light t 963.7986• Right d, s 1071.065• Right u, c 1073.026• Heavy b 1070.766• Heavy t 1081.010• Gluino 1285.116• Neut1 238.1757• Neut2 416.1312• Neut3 477.5750• Neut4 536.9010
•Slep1 152.9594•Slep2 159.9425•Slep3 159.9555•Slep4 320.8758•Slep5 322.8931•Slep6 322.9183•Snu1 312.5524•Snu2 312.8549•Snu3 312.8559•Char1 416.8510•Char2 536.9010
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Flavor-Violating Slepton NLSP Model
• Light higgs 111.6894• Heavy, Pseudoscalar Higgs 567.5025• Charged Higgs 574.1964• Left d, s 1112.478• Left u, c 1104.863• Light b 1058.783• Light t 963.9231• Right d, s 1070.985• Right u, c 1073.174• Heavy b 1070.698• Heavy t 1081.022• Gluino 1285.116• Neut1 238.2914• Neut2 416.3343• Neut3 477.8518• Neut4 536.5364
•Slep1 180.9873•Slep2 186.4298•Slep3 191.048•Slep4 302.838•Slep5 323.498•Slep6 343.3143•Snu1 292.7925•Snu2 314.1631•Snu3 333.9243•Char1 417.0538•Char2 537.1004