S. Su DOE Review, 2007

Beyond the Standard Model Phenomenology

Shufang Su • U. of Arizona

DOE Review 2007 • Progress Report

S. Su DOE Review, 2007 2

Students and Postdoc -

Postdoc

− Hock-Seng Goh ( → Berkeley in Sep. 2007)− Brooks Thomas (group postdoc, started in Sep. 2007)

Graduate Students− Ethan Dolle (5th year)− Xinyu Miao (4th year)

Undergraduate Students− Jessica Goodman (→ UC Irvine in Sep 2007)− Will Parker (Senior)

S. Su DOE Review, 2007 3

Research and Collaborations -

Phenomenology of the left-right twin Higgs models Hock-Seng Goh (U. of Arizona)

− Phenomenology of the Left-Right Twin Higgs Models Hock-Seng Goh, S. Su, Phys. Rev. D75 (2007) 075010.

Review article on the low energy precision tests of SUSY Michael. Ramsey-Musolf (Caltech)

− Low Energy Precision Tests of Supersymmetry M. Ramsey-Musolf and S. Su, hep-ph/0612057, accepted by Phys. Report.

S. Su DOE Review, 2007 4

Research and Collaborations -

Signature of SUSY in pion decay Michael Ramsey-Musolf (Caltech), Sean Tulin (Caltech)

− Pion Leptonic Decays and Supersymmetry M. Ramsey-Musolf, S. Su and S. Tulin, arXiv: 0705.0028 [hep-ph], submitted to Phys. Rev. D6

0.1 0.2 0.5 1 2 5 10

me! !mΜ!

0.0002

0.0005

0.001

0.002

0.005

"#Re!ΜSUSY"!Re!Μ

FIG. 6: ∆RSUSY

e/µ as a function of the ratio meL/mµL

. Pa-rameter points which obey the LEP II bound are dark blue; pa-rameter points which violate the LEP II bound are light blue.

In Fig. 4, we see that the ∆V + ∆L contributions (thinsolid line) vanish for large µ, since in this regime gaugino-Higgsino mixing is suppressed and there is no ∆V + ∆L

contribution to ∆RSUSYe/µ (thick solid line). However, the

∆B contribution (dashed line) is nearly µ-independent,since box graphs with Higgsino exchange are suppressedin comparison to those with only gaugino exchange. InFig. 5, we see that both ∆V + ∆L and ∆B contribu-tions vanish for large M2. One general feature observedfrom these plots is that ∆V + ∆L and ∆B contributionstend to cancel one another; therefore, the largest totalcontribution to ∆RSUSY

e/µ occurs when either ∆V +∆L or∆B is suppressed in comparison to the other. This canoccur in the following ways: (1) if µ is large, then ∆B

may be large, while ∆V + ∆L is suppressed, and (2) ifmuL

and mdLare large, then ∆V + ∆L may be large,

while ∆B is suppressed. In Fig. 5, we have chosen pa-rameters for which there is a large cancellation between∆V +∆L and ∆B. However, by taking the limits µ → ∞or muL

, mdL→ ∞, ∆RSUSY

e/µ would coincide the ∆B

or ∆V + ∆L contributions, respectively. Because of thepossibility of this cancellation, it is impossible to deter-mine whether eL or µL is heavier by measuring the signof ∆RSUSY

e/µ without knowing the details of the MSSMspectrum.

Guided by the preceding analysis, we expect for∆RSUSY

e/µ :

• The maximum contribution is∣∣∣∆RSUSY

e/µ /Re/µ

∣∣∣ ∼0.001.

100 150 200 300 500 700 1000

Min #me!$L,mΜ! $L$ %GeV&

0.0002

0.0005

0.001

0.002

0.005

"#Re!ΜSUSY"!Re!Μ

FIG. 7: ∆RSUSY

e/µ as a function of Min[meL, mµL

], the mass ofthe lightest first or second generation charged slepton. Param-eter points which obey the LEP bound are dark blue; parameterpoints which violate the LEP bound are light blue.

• Both the vertex + leg and box contributions arelargest if M2 ∼ O(mZ) and vanish if M2 $ mZ . IfM2 ∼ O(mZ), then at least one chargino must belight.

• The contributions to ∆RSUSYe/µ vanish if meL

=mµL

and are largest if either mµL% meL

ormµL

$ meL.

• The contributions to ∆RSUSYe/µ are largest if eL or

µL is light.

• If µ is heavy, then the lack of gaugino-Higgsinomixing suppresses the ∆V + ∆L contributions to∆RSUSY

e/µ .

• If uL and dL are heavy, then the ∆B contributionsto ∆RSUSY

e/µ are suppressed due to squark decou-pling.

• If uL, dL, and µ are all light, then there may becancellations between the ∆V + ∆L and ∆B con-tributions. ∆RSUSY

e/µ is largest if it is dominated byeither ∆V + ∆L or ∆B contributions.

We now study ∆RSUSYe/µ quantitatively by making a

numerical scan over MSSM parameter space, over the

8

and sign(µ) = +. It is clear that∣∣∣∆RSUSY

e/µ

∣∣∣ is largest in

the regions where either (1) µ is small, muLis large, and

the largest contributions to ∆RSUSYe/µ are from ∆V +∆L,

or (2) µ is large, muLis small, and the largest contri-

bution to ∆RSUSYe/µ is from ∆B. If both µ and muL

are

light, then ∆RSUSYe/µ can still be very small due to can-

cellations, even though both ∆V + ∆L and ∆B contri-butions are large individually. More precisely, to satisfy(25), we need either µ ! 150 GeV and muL

" 175 GeV,or µ " 350 GeV and muL

! 200 GeV (for our particu-lar choice of fixed parameters, which have been chosenfavorably toward large ∆RSUSY

e/µ ).

III. CONTRIBUTIONS FROM R-PARITYVIOLATING PROCESSES

uL eL, µL

dL νe, νµ

dRk

λ′11k for e

λ′21k for µ

FIG. 10: Tree-level RPV contributions to Re/µ.

In the presence of RPV interactions, tree-level ex-changes of sfermions (shown in Fig. 10), lead to viola-tions of lepton universality and non-vanishing effects inRe/µ. The magnitude of these tree-level contributions isgoverned by both the sfermion masses and by the pa-rameters λ′

11k and λ′21k that are the coefficients in RPV

interactions:

LRPV, ∆L=1 = λ′ijkLiQj

˜d†k + . . . (26)

Defining

∆′ijk(f) =

|λ′ijk|2

4√

2Gµm2f

≥ 0, (27)

contributions to Re/µ from RPV interactions are

∆RRPVe/µ

RSMe/µ

= 2∆′11k − 2∆′

21k. (28)

Note that RPV contribution to the muon lifetime (and,thus, the Fermi constant Gµ) cancels in Re/µ, thereforedoes not enter the expression.

The quantities ∆′ijk etc. are constrained by existing

precision measurements and rare decays. A summaryof the low energy constraints is given in Table III ofRef. [10], which includes tests of CKM unitarity (pri-marily through RPV effects in superallowed nuclear β-decay that yields a precise value of |Vud| [25]), atomic

0 1 2 3 4 5 6

x 10!3

!4

!2

0

2

4

6

8

10x 10

!3

!"

11k

!" 21k

FIG. 11: Present 95% C.L. constraints on RPV parameters∆′

j1k, j = 1, 2 that enter Re/µ obtained from a fit to pre-cision electroweak observables. Interior of the blue contourcorresponds to the fit using the current value of ∆Re/µ/RSM

e/µ

[15, 16], while the red (light) contour corresponds to the fit us-ing the future expected experimental precision [18], assumingthe same central value. The green curve indicates prospectiveimpact of a future measurement of the proton weak charge atJefferson Lab.

PV measurements of the cesium weak charge QCsW [26],

the ratio Re/µ itself [15, 16], a comparison of the Fermiconstant Gµ with the appropriate combination of α, MZ ,and sin2 θW [27], and the electron weak charge deter-mined from SLAC E158 measurement of parity violatingMøller scattering[28].

In Fig. 11 we show the present 95% C.L. constraintson the quantities ∆′

11k and ∆′21k obtained from the afore-

mentioned observables (interior of the blue curve). Sincethe ∆′

ijk are positive semidefinite quantities, only the re-gion of the contour in the upper right hand quadrant areshown. The green curve indicates the possible implica-tion of a future measurement of the proton weak chargeplanned at Jefferson Lab, assuming agreement with theStandard Model prediction for this quantity and the an-ticipated experimental uncertainty. The red curve showsthe possible impact of future measurements of Re/µ, as-suming agreement with the present central value but anoverall error reduced to the level anticipated in Ref. [18];with the error anticipated in Ref. [19] the width of theband would be a factor of two smaller than shown.

Two general observations emerge from Fig. 11. First,given the present constraints, values of ∆′

21k and ∆′11k

differing substantially from zero are allowed. For val-ues of these quantities inside the blue contour, ∆RSUSY

e/µ

could differ from zero by up to five standard deviationsfor the error anticipated in Ref. [18]. Such RPV effectscould, thus, be considerably larger than the SUSY loopcorrections discussed above. On the other hand, agree-ment of Re/µ with the SM would lead to considerabletightening of the constraints on this scenario, particu-larly in the case of ∆′

21k, which is currently constrained

SUSY Loop

RPV

S. Su DOE Review, 2007 5

Research and Collaborations -

Dark matter in the left-right twin Higgs models Jessica Goodman (U. of Arizona), Ethan Dolle (U. of Arizona)

− Relic Density Analysis of the Dark Matter Candidate E. Dolle and S. Su, in preparation.

− Direct and Indirect Detection Potential J. Goodman, E. . Dolle and S. Su, in preparation.

0 50 100 150 2000

0.05

0.1

0.15

0.2

0.25

0.3

MS (GeV)

! h

2

200 400 600 800 10000

0.05

0.1

0.15

0.2

0.25

0.3

MS (GeV)

! h

2

S. Su DOE Review, 2007 6

Research and Collaborations -

Electroweak precision analysis in various SUSY breaking scenarios Sven Heinemeyer (Instituto de Fisica de Cantabria), Xinyu Miao (U. of Arizona), Georg Weiglein (Durham)

− Electroweak Precision Data in mSUGRA, mGMSB and mAMSB S. Heinemeyer, X. Miao, S. Su and G. Weiglein, draft to be finished.

0 500 1000 1500 2000 2500 30000

10

20

30

40

50

60

SUGRA today !>0

mA (GeV)

tan!

S. Su DOE Review, 2007 7

Research and Collaborations -

Discovery potential for the heavy top quark Xinyu Miao (U. of Arizona)

− Collider Studies of the Heavy Top Quark in the Left-Right Twin Higgs Models X. Miao and S. Su, in preparation.

j

WtH

φ±

b

b

t

b

l

ν

3 b + 1 j + 1 lepton + missing ET

S. Su DOE Review, 2007 8

Research and Collaborations -

SUSY contributions to the low energy/z-pole observables Jennifer Kyle (Brookhaven), Michael Ramsey-Musolf (Madison), Sean Tulin (Caltech)

− Analysis of Precision Observables in Supersymmetry J. Kyle, M. Ramsey-Musolf, S. Su and S. Tulin, in preparation.

Sbottom in the golden region Will Parker (U. of Arizona)

− Discovery Sbottom in the Golden Region W. Parker and S. Su, in preparation.

S. Su DOE Review, 2007 9

Activities (for past year) -

• Invited talk at workshop “Fundamental Symmetries: from Nuclei and Neutrino to the Universe”

− Low Energy Precision Measurements June, 2007, Trento, Italy.

• Invited talk at international workshop on the interconnection between particle physics and cosmology

− Long Lived Charged Particles May, 2007, Texas A&M, TX.

• Invited talk at Phenomenology 2007 Symposium− Signatures in the Electroweak Symmetry Breaking Sector May, 2007, University of Wisconsin, Madison, WI.

S. Su DOE Review, 2007 10

Activities (for past year) -

• Invited talk at MC4BSM II− Left-Right Twin Higgs Models at Calchep March, 2007, Princeton, NJ

• Calchep Tutorial August, 2006, Aspen, CO

• Invited talk at Jefferson Lab Hall C 2006 Summer Workshop− Theory Overview on Neutral Current Measurements August, 2006, Jefferson Lab

• Invited talk at US-China Medium Energy Symposium− Test New Physics at Neutral Current Measurements August, 2006, Beijing, China.

S. Su DOE Review, 2007 11

Activities (for past year) -

• Invited talk at OCPA5 “International Conference on Physics Education and Frontier Physics”

− Phenomenology of the left-right Twin Higgs Models June, 2006, Taipei, Taiwan.

• Many other talks at conferences and invited seminars ...

S. Su DOE Review, 2007 12

Organization of conferences/workshops-

• Organize KITPC 2008 program: New physics beyond the Standard Model

12 weeks long program, budget of about $130 K (1M RMB)

• Convener for ALCPG07 meeting, physics signature IV working group

Charged Particle Momentum Measurement, V0 Reconstruction, and Identification of Stable Charged Particles

S. Su DOE Review, 2007 13

-

Future Plans

• LHC related physics: understand what data really means

− Communicate (more) with our exp neighbor (LHC, ALTAS)

− Train students to work on LHC physics simulation tools for new physics and SM background experimental physics observables/ capabilities …

− New physics phenomenology / distinguish various new physics

• Connection to cosmology

− New candidate for dark matter

− Collider studies of dark matter properties (ILC physics)