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SUSY in the Coannihilation Region

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1. SUSY in the Coannihilation Region. Alfredo Gurrola. LHC Phenomenology Meeting. Jan. 11, 2008 ... We have 4 observables defined as functions of 4 masses ... – PowerPoint PPT presentation

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Title: SUSY in the Coannihilation Region


1
SUSY in the Coannihilation Region
  • Alfredo Gurrola
  • LHC Phenomenology Meeting
  • Jan. 11, 2008

2
For our reference point (10 fb-1)
137 19 GeV
260 15 GeV
829 28 GeV
3
For our reference point (10 fb-1)
We can determine DM to 17 accuracy and the
gluino mass to 5!
4
SUSY in the Coannihilation Region
  • What do we already know?
  • In the previous studies, we were able to show
    that by using 4/5 observables, we can measure the
    SUSY masses as well as the dark matter relic
    density to fairly good accuracy even at 10 fb-1 .
  • Using the above methodology, we can test the idea
    of gaugino universality!!!
  • If we prove that Universality is correct, then we
    can translate our measurement of the SUSY masses
    to measurements of the SUSY model parameters.
  • What assumptions were made?
  • We assumed constant tanb and constant A0
  • Under these assumptions, m0 and m1/2 determine
    all the SUSY masses at the electroweak scale.
  • Measurement of the SUSY masses translates to a
    determination of m0 and m1/2.

5
SUSY in the Coannihilation Region
  • What do we want to know?
  • Because the other mSUGRA parameters (tanb and A0)
    also have an affect on the SUSY masses as well as
    the dark matter relic density, our previous
    methods used to determine the mSUGRA parameters
    and dark matter relic density are NOT complete.
  • We want to incorporate the effects of tanb and A0
  • How do we incorporate these effects?
  • The previous functions used to extract the SUSY
    masses from the observables were obtained by
    varying each relevant SUSY mass independently of
    the other relevant SUSY masses. For example, we
    varied DM between 5 and 15 GeV while keeping the
    other masses constant!
  • Because each mass was varied independently of the
    other masses, experimentally we are independent
    of the assumptions of Universality. How we
    extract the SUSY model parameters from the SUSY
    masses is the key to incorporating the tanb and
    A0 dependence!!
  • Since the mSUGRA parameters determine the SUSY
    masses, it is natural to try to determine tanb
    and A0 from the determination of the masses.
  • However, there is NOT enough information to
    extract all mSUGRA parameters from the
    measurement of the masses.

6
SUSY in the Coannihilation Region
  • How do the SUSY masses depend on tanb ?
  • The value of DM is very sensitive to the change
    in tanb
  • Around the reference point, variations in tanb
    have no dependence on the values of the gaugino
    masses

7
SUSY in the Coannihilation Region
  • How do the SUSY masses depend on A0 ?
  • The value of DM varies slightly with a change in
    A0
  • Around the reference point, variations in A0 have
    no dependence on the values of the gaugino masses

8
SUSY in the Coannihilation Region
  • We already know how DM and the gluino mass depend
    on m0 and m1/2.

9
SUSY in the Coannihilation Region
  • Incorporating the dependence on tanb and A0
  • Measurement of the SUSY masses DOES NOT determine
    m0, m1/2 , tanb, and A0

NOT ENOUGH INFORMATION! WE NEED 2 MORE
OBSERVABLES THAT WILL GIVE US ANOTHER FUNCTION OF
TANb AND A0!
10
SUSY in the Coannihilation Region
  • From the extraction of the SUSY masses, if
    gaugino universality is correct, then the gaugino
    masses determines m1/2. However, since DM depends
    on m0, tanb, and A0, we need at least two more
    observables that are functions of m0, tanb, and
    A0.
  • Effective Mass (Meff)
  • Measures the SUSY scale (Analysis done by Paige
    and collaborators)
  • Has been shown to be a function of the gluino or
    squark mass
  • Event Selection for effective mass measurement
  • At least 4 non-b jets with PT,4 gt 50 GeV and PT,1
    gt 100 GeV
  • Zero isolated electrons or muons with PT gt 20 GeV
    and h lt 2.5
  • Missing Transverse Energy gt 200 GeV
  • Missing Transverse Energy gt 0.2 Meff

11
SUSY in the Coannihilation Region
  • ETj1 gt 100 GeV, ETj2,3,4 gt 50 GeV No es,
    ms with pT gt 20 GeV
  • Meff gt 400 GeV (Meff ? ETj1ETj2ETj3ETj4
    ETmiss No b jets eb 50)
  • ETmiss gt max 100, 0.2 Meff

At Reference Point
Meffpeak 1274 GeV
12
SUSY in the Coannihilation Region
  • How does Meff depend on m1/2 and m0?
  • Error band reflects the uncertainties at 10 fb-1
  • Good sensitivity at 10 fb-1
  • Peak is insensitive to A0 and tanb

13
SUSY in the Coannihilation Region
  • ETj1 gt 100 GeV, ETj2,3,4 gt 50 GeV No es,
    ms with pT gt 20 GeV
  • Meff(b) gt 400 GeV (Meff(b) ? ETj1bETj2ETj3ETj
    4 ETmiss j1 b jet)
  • ETmiss gt max 100, 0.2 Meff

At Reference Point
Meff(b)peak 1026 GeV
14
Meff(b) vs. mSUGRA Parameters
15
dm0 / m0 4.9 dm1/2 / m1/2 3
We have made a determination of the masses
1s ellipse
The gaugino masses determine m1/2
dtanb / tanb 7.8 dA0 25 GeV
Incorporating the Meff and Meff(b) observables
Writing DM as a function of the model parameters
1s ellipse
We can determine the model parameters!!!
16
We have made a determination of the mSUGRA model
parameters
The Dark Matter relic density depends on the
model parameters
We can determine DM to 17 accuracy and Wh2 to
35
17
SUSY in the Coannihilation Region
  • A different approach to incorporating the tanb
    and A0 dependence
  • Parameterize the observables as functions of the
    mSUGRA parameters
  • Invert the equations to obtain the mSUGRA
    parameters as functions of the observables.
  • Therefore, we need at least 4 good observables to
    use the above method
  • NOTE The above methodology will only be accurate
    if we know that Universality is correct. If the
    results using this method do not agree with the
    previously discussed method, then this also
    proves that we live in a Non-Universal world.

18
Meff(b) vs. mSUGRA Parameters
19
SUSY in the Coannihilation Region
  • How does Meff depend on m1/2 and m0?
  • Error band reflects the uncertainties at 10 fb-1
  • Good sensitivity at 10 fb-1
  • Peak is insensitive to A0 and tanb

20
SUSY in the Coannihilation Region
  • How does the ditau mass vary with the mSUGRA
    parameters?

21
SUSY in the Coannihilation Region
  • How does the jtt mass vary with the mSUGRA
    parameters?

p
p
  • jtt mass DOES NOT depend on tanb and A0 because
  • variations in A0 and tanb only change DM. As we
    have
  • already seen, there is NO dependence on stau
    mass.

22
SUSY in the Coannihilation Region
  • How does the jtt mass vary with m0?
  • Within the Coannihilation region (5 15 GeV),
    variations in m0 DO NOT produce significant
    changes in the jtt mass.

23
We have 4 observables defined as functions of 4
parameters
dtanb / tanb 2.2 dA0 16 GeV
dm0 / m0 2.0 dm1/2 / m1/2 1.2
24
We have made a determination of the mSUGRA model
parameters
The Dark Matter relic density depends on the
model parameters
At 10 fb-1, we can determine Wh2 to 11
25
SUSY in the Coannihilation Region
  • How does the uncertainty in the Dark Matter relic
    density change with Luminosity?

26
Webpage for LHC Pheno. Project
  • All plots shown in these slides (along with
    other plots) will be placed on a webpage
  • http//hepr8.physics.tamu.edu/hep/twotau
  • Click on the link titled Plots

27
t ID Efficiency
  • What is the current t ID efficiency for CMS at
    20 GeV according to Monte Carlo?
  • Shrinking DR signal cone of 5.0 / PT
  • Flat DR Tracker isolation annulus 0.07 lt DR lt
    0.5
  • t ID requirements
  • Seed track PT gt 5 GeV
  • Zero tracks with PT gt 1 GeV
  • in the isolation annulus
  • Still Optional Zero neutral
  • pions or photons in the
  • isolation annulus

28
BACKUP SLIDES
29
SUSY in the Coannihilation Region
We can combine the soft t to the jet from the
squark decay to provide another mass peak
M1/2 342 GeV
Peak can be good observable!!!!!!!
p
p
M1/2 365 GeV
30
SUSY in the Coannihilation Region
A0 -20 GeV Mjt Peak 157 GeV
A0 50 GeV Mjt Peak 185.3 GeV
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