Bhaskar Dutta
description
Transcript of Bhaskar Dutta
1
Bhaskar Dutta
Texas A&M University
Phenomenology Projects
2
QuestionsSome Outstanding Issues of High Energy Theory
1. Dark Matter content ( is 27%)
2. Electroweak Scale
3. Baryon Content ( is 5%)
4. Rapid Expansion of the Early Universe
5. Neutrino Mass . . . Need: Theory, Experiment and Observation
DM
b
3
Current StatusCollider Experiments: LHCDirect Detection Experiments: DAMA, CDMS, XENON 100, CoGeNT, LUX etc.Indirect Detection Experiments: Fermi, AMS, PAMELACosmic Microwave Sky: PlanckNeutrino Experiments: T2K, Daya Bay, Double CHOOZ, RENO etc.
What have we learnt? What is the status of theory models? What do we expect in the near future?Are we closing in?
4
LHC: SupersymmetryMost models predict: 1-3 TeV (colored particle masses)So far: No colored particle up to 1.5 TeV
Non-colored SUSY particles: 100 GeV to 1-2 TeV (Major role in the DM content of the Universe) Weak LHC bound for non-colored particles hole in searches!
Trouble in Models with very tight correlation between colored and non-colored particles , e.g., minimal SUGRA/CMSSM
LHC + Direct Detection + Indirect Detection quite constraining
Origin of Dark Matter-ThermalProduction of thermal DM:
Thermal ModelsFreeze-Out: Hubble expansion dominates over the interaction rate
Non-relativistic
5
v1~DM
20~ DM
fmT
Dark Matter Content:
Assuming : 2
2
~v
mf~O(10-2) with m ~ O(100) GeV leads to the correct relic abundance
m/Tfreeze out
ffDMDM
scm3
26103v
Thermal Dark MatterDM particle + DM Particle SM particles
Annihilation Cross-section Rate:
6
vann
DM
DM
DM
DM
f: SM particles; h, H, A: various Higgs, : SUSY particleNote: All the particles in the diagram are colorless
v1~DM
DM Abundance:
f~
scm3
26103v We need to satisfy thermal DM requirement
7
Suitable DM Candidate: Weakly Interacting Massive Particle (WIMP)
Typical in Physics beyond the SM (LSP, LKP, …)
Most Common: Neutralino (SUSY Models)
Neutralino: Mixture of Wino, Higgsino and Bino
Larger/Smaller Annihilation Non-thermal Models
Thermal Dark Matter
Larger annihilation cross-section
smaller annihilation cross-section
v1~DM
8
Dark Matter at the LHCAnnihilation of lightest neutralinos quarks, leptons etc.At the LHC: proton + proton DM particles
DM Annihilation diagrams: mostly non-colored particles e.g., sleptons, staus, charginos, neutralinos, etc.
How do we produce these non-colored particles and the DM particle at the LHC? Can we measure the annihilation cross-section ? 1. Cascade decays of squarks and gluinos2. Monojet Searches3. Via stop squark4. Vector Boson fusion
TAMU Theory+ Experiment Collaboration
vann
9
The signal : jets + leptons+ t’s +W’s+Z’s+H’s + missing ET
1. Via Cascade decays at the LHC
(or l+l-, tt)
DM
DMColored particles are produced and they decay finally into the weakly interacting stable particle
High PT jet
High PT jet
[mass difference is large]
The pT of jets and leptons depend on the sparticle masses which are given by models
R-parity conserving
(or l+l-, tt)LHC is very complicated
10
1. Via Cascade decays at the LHCAmbitious Goal:
Final states Masses Model Parameters Calculate dark matter density
We may not be able to solve for masses of all the sparticles in a model
Challenge: Solving for the MSSM
01
~~ lqQ 01
~~ lL0
10
4,3,2~,,~ llhZ etc. Identifying one side
is very tricky!
Not all the sparticles appear in cascade decays
Problem 1:
Problem 2:Apply :Bi-Event Subtraction Technique (BEST)Dutta, Kamon, Krislock, ‘12
11
1fb 10 L
1fb 50
1111
1. Via Cascade decays at the LHCmSUGRA Non Universal Higgs Model
@ 200 fb-1
1fb 001
Mirage Mediation Model
Determine DM content at14 TeV LHC with high luminosityIf squarks are produced
Arnowitt, Dutta, Kamon, Gurrola, Krislock, Toback: PRL 100 (2008) 231802
Dutta, Kamon, Krislock, Sinha, Wang: Phys.Rev. D85 (2012) 115007
Dutta, Gurrola,Kamon, Krislock, Mavromatos, Nanopoulos: Phys.Rev. D79 (2009) 055002
12
3. DM via Monojet at LHC
1 2
Monojet Dijet
Dutta, Gao, Kamon: In preparation
Allahverdi, Dutta: Phys.Rev. D88 (2013) 023525
13
3. DM via Monojet at LHC
:Dijet pair
Dutta, Gao, Kamon: In preparation
3. DM via Stop at 8 TeV LHC
14
LHC Stop pair productions up to ~ 600 GeV @ 8 TeV LHCUtilize Stop decay modes to search charginos, sleptons, neutralinos
Ex. 1 is mostly bino and is wino
Topness variable to identify stops
2 jets+ 2 leptons (OSSF-OSDF)+missing energy
Existence and type of DM particle, hard to calculate the DM content
Stop can identified via fully hadronic or 1 lepton plus multijet final states
Ex. 3 is mostly Bino-Higgsino Correct relic density
01 0
2
Ex. 2 are mostly Higgsino02,1
01
For lighter sleptons
[Yang Bai, Cheng, Gallichio, Gu, 1203.4813;Han, Katz, Krohn, Reece, 1205.5808;Plehn, Spannowsky, Takeuchi, 1205.2696;Kaplan, Rehermann, Stolarski, 1205.5816; Dutta, Kamon, Kolev, Sinha, Wang, 1207.1893]
Grasser, Shelton, 2012
Dutta, Kamon, Kolev, Wang, Wu, Phys.Rev. D87 (2013) 095007
3. DM via Stop at 8 TeV LHC
15
Bino-Higgsino dark matter
GeV6501
02
mm
GeV11001
m
Correct dark matter content
5 (s/(s+B)) : for lightest stop mass ~ 600 GeV at 30 fb-1
Dilepton end-point after OSSF-OSDF including background
Dutta, Kamon, Kolev, Wang, Wu, Phys.Rev. D87 (2013) 095007
4. DM at the LHC Via VBF
16
LHC has a blind spot for productions of non-colored particle
The W boson (colorless) coming out of high energy protons can produce colorless particlesVector Boson Fusion(VBF)
Special search strategy needed to extract the signal
New way of understanding DM or new physics sector at the LHC
Theory + Experiment Collaboration
Delannoy, Dutta, Kamon, Sinha, Wang, Wu et al; Phys.Rev.Lett. 111 (2013) 061801Dutta, Gurrola, Kamon, John, Sinha, Shledon; Phys.Rev. D87 (2013) 035029Dutta, Eusebi, Gao, Ghosh, Kamon: In preparationDutta, Flanagan, Johns, Kamon, Gurrola, Sheldon, Sinha, Wang, Wu: arXiv:1312.1348; In preparationDutta, Gao, Kamon, Shakya: In preparation
4. DM at the LHC Via VBF
17
jjjjjjjjpp 02
02
0211111
~~,~~,~~,~~
Signal: missing energy,
t22 j missing energy
22 j
For : 01
021
~,mmmm l
LHC 8 TeV data (expected): 260 GeV [ 180 GeV [
jjpp ~~
LHC 14 TeV data (expected): To appear soon
Signal: missing energy,
22 j
22 j missing energy] t22 j missing energy]
18
Cross Sections via VBFDM via VBFDM at the LHCjjpp 0
10
1~~
CDM
19
DM Content via VBFSimultaneous fit of the observed rate, shape of missing energy distribution:
Phys.Rev.Lett. 111 (2013) 061801
4. DM at the LHC Via VBF
20
Direct probes of colorless charginos, neutralinos and sleptons do not have strong limits from the LHC
The weak Bosons from protons can produce
P + P
Two high ET forward jets in opposite hemispheres with large dijet invariant mass
DM
21
Ongoing Projects
1. Double charged Higgs Boson search: VBF This model arises in the context of L-R symmetry [Dutta, Eusebi, Gao, Ghosh, Kamon, In progress]
2. NMSSM : 126 GeV Higgs is easily explainedVBF production of the neutralino sector: 2 jet+4 b signal[Dutta, Gao, Ghosh, Shakya, In progress]
3. VBF searches for light sbottom, In preparation
4. VBF searches for 3 body decay modes of stop, In preparation
22
Concluding Insights Model ideas have constraints from LHC, Planck, Neutrino data, direct and indirect detection constraints Higgs mass is within the supersymmetry model prediction window LHC measurements so far seem to be preferring large DM annihilation cross-section Non-thermal DM
Non-thermal scenarios can accommodate both large and small annihilation cross-sections and can allow us to understand the baryon-DM coincidence puzzle
Determination of the DM Annihilation Cross-section is crucial: LHC and Indirect detections identify DM modelNeed to investigate colorless particles (suitable for DM calculation) at the LHC using vector Boson technique