spice: simulation package for including flavor in collider events felix yu university of california,...

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]

West Coast LHC Theory Meeting, April 17, 2009

2

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


3

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


4

mSUGRA

mGMSB “Spine”

mAMSB

What is SPICE?

Flavor-violating

parameters

(U(1) charges or

user-defined)

SPICE

SUSY spectrum and flavor-general decay widths


5

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…


6

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


7


8


9

Flavor-Violating Slepton NLSP Model


10

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)


11

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)


12

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


13

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


14

Flavor Information in the Bino Reconstruction?

• Invariant mass of 1e and 1after cut on

pT

Preliminary, Work in Progress


15

Flavor Information in the Bino Reconstruction?

• Zooming in on the hard-pT cut plots

Preliminary, Work in Progress


16

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


17

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


18

Backup Slides


20

Flavor-Conserving Bino NLSP Model


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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


22

Flavor-Violating Bino NLSP Model


23



24


• 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


25

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


26

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


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Flavor-Violating Parameters

spice: simulation package for including flavor in collider events felix yu university of california,...

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