Some collider signals of the invisible and the visible: adiscourseinspiredbydarkmatter
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based Particle Physics Harish-Chandra Research Institute Allahabad, India
March, 2017
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter The LHC...
p p )( Ecm =7/8/13/14 TeV
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Heavy particles decay into lighter ones The particles are ‘boosted’: t = t / 1 v 2/c2 rest The stable/long-lived products are intercepted by di↵erent componentsp of detectors
Once collisions take place...
Many particles (known/unknown) can be produced
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter The particles are ‘boosted’: t = t / 1 v 2/c2 rest The stable/long-lived products are intercepted by di↵erent componentsp of detectors
Once collisions take place...
Many particles (known/unknown) can be produced Heavy particles decay into lighter ones
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter The stable/long-lived products are intercepted by di↵erent components of detectors
Once collisions take place...
Many particles (known/unknown) can be produced Heavy particles decay into lighter ones The particles are ‘boosted’: t = t / 1 v 2/c2 rest p
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Once collisions take place...
Many particles (known/unknown) can be produced Heavy particles decay into lighter ones The particles are ‘boosted’: t = t / 1 v 2/c2 rest The stable/long-lived products are intercepted by di↵erent componentsp of detectors
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter The CMS detector ...
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter The ATLAS detector...
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter The dimension of a detector...
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter The sequence of various layers of a detector has a particular logic......
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Not detected in any part of the detector The only LHC signal of such particles: imbalance of transverse momentum of all visible particles ‘MET’ The standard model candidates for MET: the three neutrinos Any additional ‘invisible’ particles Events with MET even after ‘subtracting’ ) the e↵ect of neutrinos Such particles can contribute to the dark matter content of the universe
Now think of...... Some particle(s) having neither strong not electromagnetic interaction
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter The only LHC signal of such particles: imbalance of transverse momentum of all visible particles ‘MET’ The standard model candidates for MET: the three neutrinos Any additional ‘invisible’ particles Events with MET even after ‘subtracting’ ) the e↵ect of neutrinos Such particles can contribute to the dark matter content of the universe
Now think of...... Some particle(s) having neither strong not electromagnetic interaction Not detected in any part of the detector
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter The standard model candidates for MET: the three neutrinos Any additional ‘invisible’ particles Events with MET even after ‘subtracting’ ) the e↵ect of neutrinos Such particles can contribute to the dark matter content of the universe
Now think of...... Some particle(s) having neither strong not electromagnetic interaction Not detected in any part of the detector The only LHC signal of such particles: imbalance of transverse momentum of all visible particles ‘MET’
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Any additional ‘invisible’ particles Events with MET even after ‘subtracting’ ) the e↵ect of neutrinos Such particles can contribute to the dark matter content of the universe
Now think of...... Some particle(s) having neither strong not electromagnetic interaction Not detected in any part of the detector The only LHC signal of such particles: imbalance of transverse momentum of all visible particles ‘MET’ The standard model candidates for MET: the three neutrinos
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Such particles can contribute to the dark matter content of the universe
Now think of...... Some particle(s) having neither strong not electromagnetic interaction Not detected in any part of the detector The only LHC signal of such particles: imbalance of transverse momentum of all visible particles ‘MET’ The standard model candidates for MET: the three neutrinos Any additional ‘invisible’ particles Events with MET even after ‘subtracting’ ) the e↵ect of neutrinos
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Now think of...... Some particle(s) having neither strong not electromagnetic interaction Not detected in any part of the detector The only LHC signal of such particles: imbalance of transverse momentum of all visible particles ‘MET’ The standard model candidates for MET: the three neutrinos Any additional ‘invisible’ particles Events with MET even after ‘subtracting’ ) the e↵ect of neutrinos Such particles can contribute to the dark matter content of the universe
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter If MET indicates new invisible particles,
The total standard model (SM) contribution needs to estimated and subtracted One also needs to estimate ‘fake’ MET arising from, say, mismeasurement of jet energy, pile-up e↵ects etc.
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Estimating the SM/residual MET in a ‘control region’.....
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Then looking for new physics with large MET.....
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter CMBR anisotropy
Observation of bullet clusters
Observation of -ray signals, excess positrons, excess in galactic antiproton/proton ratio....
Outcomes of direct search experiments
Missing energy in collider experiments (Attempt to reconstruct masses from mT 2, mcT , psˆmin,...)
Dark matter is indicated/expected to show up in.... Galactic rotation curves
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Observation of bullet clusters
Observation of -ray signals, excess positrons, excess in galactic antiproton/proton ratio....
Outcomes of direct search experiments
Missing energy in collider experiments (Attempt to reconstruct masses from mT 2, mcT , psˆmin,...)
Dark matter is indicated/expected to show up in.... Galactic rotation curves
CMBR anisotropy
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Observation of -ray signals, excess positrons, excess in galactic antiproton/proton ratio....
Outcomes of direct search experiments
Missing energy in collider experiments (Attempt to reconstruct masses from mT 2, mcT , psˆmin,...)
Dark matter is indicated/expected to show up in.... Galactic rotation curves
CMBR anisotropy
Observation of bullet clusters
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Outcomes of direct search experiments
Missing energy in collider experiments (Attempt to reconstruct masses from mT 2, mcT , psˆmin,...)
Dark matter is indicated/expected to show up in.... Galactic rotation curves
CMBR anisotropy
Observation of bullet clusters
Observation of -ray signals, excess positrons, excess in galactic antiproton/proton ratio....
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Missing energy in collider experiments (Attempt to reconstruct masses from mT 2, mcT , psˆmin,...)
Dark matter is indicated/expected to show up in.... Galactic rotation curves
CMBR anisotropy
Observation of bullet clusters
Observation of -ray signals, excess positrons, excess in galactic antiproton/proton ratio....
Outcomes of direct search experiments
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Dark matter is indicated/expected to show up in.... Galactic rotation curves
CMBR anisotropy
Observation of bullet clusters
Observation of -ray signals, excess positrons, excess in galactic antiproton/proton ratio....
Outcomes of direct search experiments
Missing energy in collider experiments (Attempt to reconstruct masses from mT 2, mcT , psˆmin,...)
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Relic density in the case of thermal DM—- via Boltzmann equation
Light element abundance.
Various astro-cosmo data (time-dependent!)
Most proposed theoretical scenarios faces constraints from...
Various direct search experiments– mostly spin-independent scattering cross-sections with nucleons.
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Light element abundance.
Various astro-cosmo data (time-dependent!)
Most proposed theoretical scenarios faces constraints from...
Various direct search experiments– mostly spin-independent scattering cross-sections with nucleons.
Relic density in the case of thermal DM—- via Boltzmann equation
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Various astro-cosmo data (time-dependent!)
Most proposed theoretical scenarios faces constraints from...
Various direct search experiments– mostly spin-independent scattering cross-sections with nucleons.
Relic density in the case of thermal DM—- via Boltzmann equation
Light element abundance.
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Most proposed theoretical scenarios faces constraints from...
Various direct search experiments– mostly spin-independent scattering cross-sections with nucleons.
Relic density in the case of thermal DM—- via Boltzmann equation
Light element abundance.
Various astro-cosmo data (time-dependent!)
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter The DM candidate has very feeble interaction + The signal is NOT missing energy/momentum at collider experiments
There can still be scenarios, where....
DM-related issues face some twist for certain particle spectra Change in the basic paradigm for ) formulating/probing new physics
Example:
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter There can still be scenarios, where....
DM-related issues face some twist for certain particle spectra Change in the basic paradigm for ) formulating/probing new physics
Example: The DM candidate has very feeble interaction + The signal is NOT missing energy/momentum at collider experiments
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter ....
Points illustrated in the context of supersymmetry (SUSY)
SUSY: The action has a boson-fermion symmetry Abosonforeveryfermionandviceversa ) SUSY with particle-superpartner split TeV avoids ' unacceptable shifts in the Higgs boson mass via higher-order corrections
SUSY ADMcandidatearisingina ) ‘not-so-artificial’ manner However, similar possibilities in non-SUSY contexts can be of interest Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter The minimum SUSY scenario (MSSM) spectrum...
Minimal SUSY Standard Model (MSSM)
Chiral superfields:
Names spin 0 spin 1/2 SU(3)C,SU(2)L, . U(1)Y squarks, quarks 1 Q (uL dL) (uL dL) ( 3, 2 , 6) c 2 (3 families) U u u† (3, 1, ) R⇤ R 3 c e 1 D e dR⇤ dR† (3, 1, 3) sleptons, leptons 1 L (⌫eeL) (⌫eL) ( 1, 2 , 2) c (3 families) E eeR⇤ eR† ( 1, 1, 1) Higgs, higgsinos + 0 + 0 1 Hu (Hue eHu ) (Hu Hu ) ( 1, 2 , +2) 0 0 1 Hd (Hde Hd ) (Hd Hd ) ( 1, 2 , 2) e e e e
Gauge superfields :
Names spin 1/2 spin 1 SU(3)C,SU(2)L,U(1)Y gluino, gluon g g ( 8, 1 , 0) 0 0 winos, W bosons W ± W W ± W ( 1, 3 , 0) bino, B boson Be0 B0 ( 1, 1 , 0) f f e
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research0 and Institute the visible: Allahabad, a discourse India inspired by dark matter +gravitino? (Not considered in the present discussion)
Physical states important in phenomenology:
˜ ˜ Charginos: 1±,2 =(...)W ± +(...)H± 0 ˜ ˜ 3 ˜0 ˜0 Neutralinos: 1,2,3,4 =(...)B + W +(...)H1 +(...)H2
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter R-conserving SUSY the lightest superparticle is stable )
AsourceofMissingET at the LHC: Adarkmattercandidate (Subject to direct search + relic density constraints) The most suitable candidate in MSSM: 0 the lightest neutralino ( 1) Expected signal of SUSY with a DM candidate: MET + jets/leptons/photons
In a supersymmetric scenario....
R =( )(3B+L+2J) is +1 for all SM particles, -1 for superparticles Rconservedmultiplicatively,ifnoB/Lviolation by odd units
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter AsourceofMissingET at the LHC: Adarkmattercandidate (Subject to direct search + relic density constraints) The most suitable candidate in MSSM: 0 the lightest neutralino ( 1) Expected signal of SUSY with a DM candidate: MET + jets/leptons/photons
In a supersymmetric scenario....
R =( )(3B+L+2J) is +1 for all SM particles, -1 for superparticles Rconservedmultiplicatively,ifnoB/Lviolation by odd units R-conserving SUSY the lightest superparticle is stable )
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter The most suitable candidate in MSSM: 0 the lightest neutralino ( 1) Expected signal of SUSY with a DM candidate: MET + jets/leptons/photons
In a supersymmetric scenario....
R =( )(3B+L+2J) is +1 for all SM particles, -1 for superparticles Rconservedmultiplicatively,ifnoB/Lviolation by odd units R-conserving SUSY the lightest superparticle is stable )
AsourceofMissingET at the LHC: Adarkmattercandidate (Subject to direct search + relic density constraints)
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Expected signal of SUSY with a DM candidate: MET + jets/leptons/photons
In a supersymmetric scenario....
R =( )(3B+L+2J) is +1 for all SM particles, -1 for superparticles Rconservedmultiplicatively,ifnoB/Lviolation by odd units R-conserving SUSY the lightest superparticle is stable )
AsourceofMissingET at the LHC: Adarkmattercandidate (Subject to direct search + relic density constraints) The most suitable candidate in MSSM: 0 the lightest neutralino ( 1)
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter In a supersymmetric scenario....
R =( )(3B+L+2J) is +1 for all SM particles, -1 for superparticles Rconservedmultiplicatively,ifnoB/Lviolation by odd units R-conserving SUSY the lightest superparticle is stable )
AsourceofMissingET at the LHC: Adarkmattercandidate (Subject to direct search + relic density constraints) The most suitable candidate in MSSM: 0 the lightest neutralino ( 1) Expected signal of SUSY with a DM candidate: MET + jets/leptons/photons
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter The MSSM and ATLAS results...
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter The MSSM and CMS results...
~~ ~ ∼0 pp → gg, g → tt χ1 ICHEP 2016
2000 CMS Preliminary 12.9 fb-1 (13 TeV) miss
[GeV] SUS-16-014, 0-lep (H ) 0 18001 T Expected ∼ χ SUS-16-015, 0-lep (MT2) Observed m 1600 SUS-16-016, 0-lep (αT) SUS-16-019, 1-lep (∆φ) 1400 SUS-16-020, ≥2-lep (SS) SUS-16-022, ≥3-lep 1200 SUS-16-030, 0-lep (top tag)
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Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Adominantdecaychannel(inoneorsometimes two steps) for each sparticle is assumed in most analyses (‘simplified models’). The spectrum is constrained by the need to keep m 125GeV . h ⇡
Remember: with > 100 free parameters,...
Constraints and allowed regions are spectrum-dependent– branching ratios of sparticles crucial inputs.
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter The spectrum is constrained by the need to keep m 125GeV . h ⇡
Remember: with > 100 free parameters,...
Constraints and allowed regions are spectrum-dependent– branching ratios of sparticles crucial inputs. Adominantdecaychannel(inoneorsometimes two steps) for each sparticle is assumed in most analyses (‘simplified models’).
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Remember: with > 100 free parameters,...
Constraints and allowed regions are spectrum-dependent– branching ratios of sparticles crucial inputs. Adominantdecaychannel(inoneorsometimes two steps) for each sparticle is assumed in most analyses (‘simplified models’). The spectrum is constrained by the need to keep m 125GeV . h ⇡
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter ....
‘SUSY with organising principles’: proposed for having fewer free parameters more constrained in general Constrained MSSM (cMSSM) based on minimal supergravity: Everything determined by m0, m1/2, A0, tan ,Sgn(µ)
LHC data+DM constraints+observed mh strong constraints (more) on this later)
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter c The term y⌫lL ⌫R H2 is absent in the superpotential If neutrinos have just Dirac mass, then this term could be present ⌫˜R is there: Another potential LSP (read DM)) candidate
⌫˜R is a gauge singlet: ultra-feeble interactions It forms non-thermal DM ) The next-to-lightest SUSY particle (LSP) does not decay into the LSP within collider detectors: new collider signals )
SUSY with a right sneutrino LSP....
The MSSM has no right-handed neutrino or its superpartner
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter If neutrinos have just Dirac mass, then this term could be present ⌫˜R is there: Another potential LSP (read DM)) candidate
⌫˜R is a gauge singlet: ultra-feeble interactions It forms non-thermal DM ) The next-to-lightest SUSY particle (LSP) does not decay into the LSP within collider detectors: new collider signals )
SUSY with a right sneutrino LSP....
The MSSM has no right-handed neutrino or its superpartner c The term y⌫lL ⌫R H2 is absent in the superpotential
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter ⌫˜R is a gauge singlet: ultra-feeble interactions It forms non-thermal DM ) The next-to-lightest SUSY particle (LSP) does not decay into the LSP within collider detectors: new collider signals )
SUSY with a right sneutrino LSP....
The MSSM has no right-handed neutrino or its superpartner c The term y⌫lL ⌫R H2 is absent in the superpotential If neutrinos have just Dirac mass, then this term could be present ⌫˜R is there: Another potential LSP (read DM)) candidate
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter The next-to-lightest SUSY particle (LSP) does not decay into the LSP within collider detectors: new collider signals )
SUSY with a right sneutrino LSP....
The MSSM has no right-handed neutrino or its superpartner c The term y⌫lL ⌫R H2 is absent in the superpotential If neutrinos have just Dirac mass, then this term could be present ⌫˜R is there: Another potential LSP (read DM)) candidate
⌫˜R is a gauge singlet: ultra-feeble interactions It forms non-thermal DM )
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter SUSY with a right sneutrino LSP....
The MSSM has no right-handed neutrino or its superpartner c The term y⌫lL ⌫R H2 is absent in the superpotential If neutrinos have just Dirac mass, then this term could be present ⌫˜R is there: Another potential LSP (read DM)) candidate
⌫˜R is a gauge singlet: ultra-feeble interactions It forms non-thermal DM ) The next-to-lightest SUSY particle (LSP) does not decay into the LSP within collider detectors: new collider signals ) Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter In the scalar potential: 2 2 c soft M ⌫˜R +(y⌫A⌫Hu.L˜⌫˜ + h.c.) L ⇠ ⌫˜R | | R The low-scale sneutrino mass matrix:
2 1 2 µ 2 ML˜ + 2 mZ cos 2 y⌫v(A⌫ sin cos ) m⌫˜ = 2 y⌫v(A⌫ sin µ cos ) M ✓ ⌫˜R ◆
ML˜ =softmassfortheleft-handedsleptons
M⌫˜R =softmassfortheright-handedsneutrino
In general, ML˜ = M⌫˜R because of di↵erent evolution patterns + D-term6 contribution for the former. Physical states: ⌫˜1(lighter), ⌫˜2(heavier)
Features that a right sneutrino LSP brings in.... Assuming Dirac masses only for neutrinos, In the superpotential: Terms y l c ⌫ H mD = y H ⇠ ⌫ L R u ) ⌫ ⌫h ui
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter The low-scale sneutrino mass matrix:
2 1 2 µ 2 ML˜ + 2 mZ cos 2 y⌫v(A⌫ sin cos ) m⌫˜ = 2 y⌫v(A⌫ sin µ cos ) M ✓ ⌫˜R ◆
ML˜ =softmassfortheleft-handedsleptons
M⌫˜R =softmassfortheright-handedsneutrino
In general, ML˜ = M⌫˜R because of di↵erent evolution patterns + D-term6 contribution for the former. Physical states: ⌫˜1(lighter), ⌫˜2(heavier)
Features that a right sneutrino LSP brings in.... Assuming Dirac masses only for neutrinos, In the superpotential: Terms y l c ⌫ H mD = y H ⇠ ⌫ L R u ) ⌫ ⌫h ui In the scalar potential: 2 2 c soft M ⌫˜R +(y⌫A⌫Hu.L˜⌫˜ + h.c.) L ⇠ ⌫˜R | | R
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Features that a right sneutrino LSP brings in.... Assuming Dirac masses only for neutrinos, In the superpotential: Terms y l c ⌫ H mD = y H ⇠ ⌫ L R u ) ⌫ ⌫h ui In the scalar potential: 2 2 c soft M ⌫˜R +(y⌫A⌫Hu.L˜⌫˜ + h.c.) L ⇠ ⌫˜R | | R The low-scale sneutrino mass matrix:
2 1 2 µ 2 ML˜ + 2 mZ cos 2 y⌫v(A⌫ sin cos ) m⌫˜ = 2 y⌫v(A⌫ sin µ cos ) M ✓ ⌫˜R ◆
ML˜ =softmassfortheleft-handedsleptons
M⌫˜R =softmassfortheright-handedsneutrino
In general, ML˜ = M⌫˜R because of di↵erent evolution patterns + D-term6 contribution for the former. Physical states: ⌫˜1(lighter), ⌫˜2(heavier)
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Features that a right sneutrino LSP brings in....
With high-scale SUSY breaking generating M⌫˜R , dM2 ⌫˜R 2 2 2 dt = 16⇡2 y⌫ A⌫ Extremely small Yukawa couplings M nearly frozen at the high-scale value ) ⌫˜R Other sfermion masses are jacked up at the electroweak scale Aright-chiralsneutrinoforeveryfamilyisatthe bottom) of the spectrum
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Features that a right sneutrino LSP brings in....
The LSP state(s) =˜⌫1 Dominantly ⌫˜R ,withadmixtureof⌫˜L y⌫ 2 ⇠ All decay widths into ⌫˜1 is y⌫ Extremely suppressed– decay⇠ takes place outside detector Within the detector, all decays lead to the NLSP The NLSP controls collider phenomenology Example: For a stau-NLSP, there will be long-lived charged tracks Signal: tracks in the tracker/muon chamber + jets + leptons
No Missing-ET signal for SUSY, in spite of a DM candidate in the spectrum
The ⌫˜R changes signals simply by remaining supremely inert!
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter ...
Gregory (Scotland Yard detective): ”Is there any other point to which you would wish to draw my attention?”
Holmes: ”To the curious incident of the dog in the night-time.”
Gregory: ”The dog did nothing in the night-time.” Holmes: ”That was the curious incident.”
Silver Blaze in The Memoirs of Sherlock Holmes by Sir Arthur Conan Doyle
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter The stable tracks will leave their mark in the tracking chamber, and will also arrive at the muon chamber Thus they need to be distinguished from muons
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Ways to separate the stable tracks from muons: pT (track)...
The distribution is much harder for ⌫˜1-LSP: S. K. Gupta + BM + S. K. Rai (2007), S. Biswas + BM (2010)
(a) Benchmark point 1 . 1000 Benchmark point 2 SM Background
100
Number of Events 10
1 0 200 400 600 800 1000 p (GeV) T Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Ways to separate: ⌃ p ... | T |
(c) Benchmark point 1 1000 Benchmark point 2 SM Background
100
Number of Events 10
1 0 400 800 1200 1600 2000 p (GeV) T
Also used: Time-delay between inner tracker and muon chamber, ‘stopper detector’, dE/dx measurements... K. Hamaguchi, M. Nojoiri, A. de Roeck (2006), CMS (2011), ATLAS (2015)... Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Regions above this range: can be probed at 13/14 TeV, 1 upto 5 with 1000 fb ,usingjustpT -based event selection.
...
Model-independent limits on stau NLSP from stable charged track search at (8 + 13) TeV LHC: 360 GeV ⇡
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter ...
Model-independent limits on stau NLSP from stable charged track search at (8 + 13) TeV LHC: 360 GeV ⇡
Regions above this range: can be probed at 13/14 TeV, 1 upto 5 with 1000 fb ,usingjustpT -based event selection.
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Relic density: The stau-NLSP decays well after freeze-out
Thus ⌦⌫˜R =⌦⌧˜1 m⌫˜R /m⌧˜1
⌦⌧˜1 obtained by solving Boltzmann equation One can check if ⌦ is consistent ) ⌫˜R (only if non-thermal production is neglected) Constraints depend on whether or not
m⌧˜1 , m⌫˜R come from the same m0
Right sneutrino LSP: Constraints to satisfy
Lower limit on the stable stau mass
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Right sneutrino LSP: Constraints to satisfy
Lower limit on the stable stau mass Relic density: The stau-NLSP decays well after freeze-out
Thus ⌦⌫˜R =⌦⌧˜1 m⌫˜R /m⌧˜1
⌦⌧˜1 obtained by solving Boltzmann equation One can check if ⌦ is consistent ) ⌫˜R (only if non-thermal production is neglected) Constraints depend on whether or not
m⌧˜1 , m⌫˜R come from the same m0
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter m 125 GeV + observed LHC signal strengths h ⇡
Right sneutrino LSP: Constraints to satisfy
Big-bang nucleosynthesis (BBN) and light-element abundance: ⌧˜ -lifetime 100s (approx) ) 1 Constraints on y , ⌧˜ ⌧˜ mixing ) ⌫ L R constraints on µ ) constraints on EWSB conditions )
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Right sneutrino LSP: Constraints to satisfy
Big-bang nucleosynthesis (BBN) and light-element abundance: ⌧˜ -lifetime 100s (approx) ) 1 Constraints on y , ⌧˜ ⌧˜ mixing ) ⌫ L R constraints on µ ) constraints on EWSB conditions m) 125 GeV + observed LHC signal strengths h ⇡
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter LHC signals: high energy run
Looking for two stable stau tracks + 2 hard ( 70 GeV) jets: three cut sets for stau track identification
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Cut set B: pT and minv cuts slightly relaxed, but slower tracks included Cut set C: pT and minv cuts much more relaxed but only delayed tracks chosen
Conclusion: pT -based cuts work well for lower stau-masses, but time-delay selection wins for higher masses
Remarks on the chosen cut-sets
Cut set A: Sti↵ pT and minv cuts but only fast tracks chosen
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Cut set C: pT and minv cuts much more relaxed but only delayed tracks chosen
Conclusion: pT -based cuts work well for lower stau-masses, but time-delay selection wins for higher masses
Remarks on the chosen cut-sets
Cut set A: Sti↵ pT and minv cuts but only fast tracks chosen Cut set B: pT and minv cuts slightly relaxed, but slower tracks included
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Conclusion: pT -based cuts work well for lower stau-masses, but time-delay selection wins for higher masses
Remarks on the chosen cut-sets
Cut set A: Sti↵ pT and minv cuts but only fast tracks chosen Cut set B: pT and minv cuts slightly relaxed, but slower tracks included Cut set C: pT and minv cuts much more relaxed but only delayed tracks chosen
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Remarks on the chosen cut-sets
Cut set A: Sti↵ pT and minv cuts but only fast tracks chosen Cut set B: pT and minv cuts slightly relaxed, but slower tracks included Cut set C: pT and minv cuts much more relaxed but only delayed tracks chosen
Conclusion: pT -based cuts work well for lower stau-masses, but time-delay selection wins for higher masses
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter LHC signals: high energy run
Some signal and background rates: m⌧˜1 = 350 - 600 GeV, mg˜, mq˜ = 2.2 - 3.6 TeV
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Acuriosity....
Question: Do the constraints on mSUGRA-based cMSSM change for a ⌫˜R DM? Yes, because
(a) m⌧˜ < m 0 now allowed 1 1 (b) The DM is non-thermal now S. Banerjee, G. Belanger, BM, P. D. Serpico, JHEP 07 (2016) 095
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Direct search limits going up some annihilation channels become ine) ↵ective m , m 0 , m are related: so are m ,˜ g˜ 1 1± q˜ ` 0 µ gets fixed, so the Higgsino component in 1 cannot be tweaked
0 The limits on cMSSM with 1 DM are strong because....
m0, m1/2 also a↵ect Higgs mass(es)
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter m , m 0 , m are related: so are m ,˜ g˜ 1 1± q˜ ` 0 µ gets fixed, so the Higgsino component in 1 cannot be tweaked
0 The limits on cMSSM with 1 DM are strong because....
m0, m1/2 also a↵ect Higgs mass(es) Direct search limits going up some annihilation channels become ine) ↵ective
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter 0 µ gets fixed, so the Higgsino component in 1 cannot be tweaked
0 The limits on cMSSM with 1 DM are strong because....
m0, m1/2 also a↵ect Higgs mass(es) Direct search limits going up some annihilation channels become ine) ↵ective m , m 0 , m are related: so are m ,˜ g˜ 1 1± q˜ `
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter 0 The limits on cMSSM with 1 DM are strong because....
m0, m1/2 also a↵ect Higgs mass(es) Direct search limits going up some annihilation channels become ine) ↵ective m , m 0 , m are related: so are m ,˜ g˜ 1 1± q˜ ` 0 µ gets fixed, so the Higgsino component in 1 cannot be tweaked
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter mSUGRA-based cMSSM has strong limits...
Red solid: 68%C.L., Blue solid:95%C.L. From O. Buchmueller et al., EPJC 74.2922(2014)
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter mSUGRA-based cMSSM limits: all constraints included
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter mSUGRA-based cMSSM limits: all constraints included
mLSP allowed to be di↵erent from m0
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter To conclude...
To verify any dark matter scenario in a terrestrial (read accelerator) experiment, it may be too restrictive to think in terms of stereotyped signals!
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter For m 440 GeV, tan 33 stau1 ⇡ ⇡
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Problem with Li overproduction: optimal 3 solution prefers ⌧m 10 s ⌧˜R ⇡ M. Pospelov et al., (2007, 2009) Abundance issues are satisfied for certain absolute values of neutrino masses
In the stauR NLSP, snuR LSP scenario...
General BBN constraints satisfied by tweaking
m⌧˜R vs. m⌫˜R T. Asaka, K. Ishiwaka, T. Moroi (2005, 2006)....
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Abundance issues are satisfied for certain absolute values of neutrino masses
In the stauR NLSP, snuR LSP scenario...
General BBN constraints satisfied by tweaking
m⌧˜R vs. m⌫˜R T. Asaka, K. Ishiwaka, T. Moroi (2005, 2006).... Problem with Li overproduction: optimal 3 solution prefers ⌧m 10 s ⌧˜R ⇡ M. Pospelov et al., (2007, 2009)
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter In the stauR NLSP, snuR LSP scenario...
General BBN constraints satisfied by tweaking
m⌧˜R vs. m⌫˜R T. Asaka, K. Ishiwaka, T. Moroi (2005, 2006).... Problem with Li overproduction: optimal 3 solution prefers ⌧m 10 s ⌧˜R ⇡ M. Pospelov et al., (2007, 2009) Abundance issues are satisfied for certain absolute values of neutrino masses
Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter Biswarup Mukhopadhyaya Regional Centre for Accelerator-based ParticleSome Physics collider Harish-Chandra signals of the invisible Research and Institute the visible: Allahabad, a discourse India inspired by dark matter