Vector Boson Fusion A powerful tool to discover new physics at the LHC
Andr´esFl´orez
July 31, 2018
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at the 1 / LHC31 Generalities of the Standard Model (SM)
Fundamental particles and their 2 † † 2 V (φ) = −µ φ (φ) + λ(φ φ) (2) interactions:
Abelian higgs potential SU(3)C ⊗ SU(2)L ⊗ U(1)Y, (1) ) φ u c t γ V(
d s b g H
Im( φ e µ τ Z Boson de Higgs ) φ Re( )
W νe νµ ντ 2 2 2 ν 2 µ Quarks Leptones Bosones |h0|φ|0i| = , with ν = − (3) 2 λ
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at the 2 / LHC31 The Large Hadron Collider (LHC)
Figure: Sketch of the LHC. The main Figure: Sketch of the acceleration chain at the experiments are: CMS, ATLAS, ALICE and LHC LHCb
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at the 3 / LHC31 The Large Hadron Collider (LHC)
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at the 4 / LHC31
Figure: Sketch of the acceleration chain at the LHC The Large Hadron Collider (LHC)
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at the 5 / LHC31 Figure: Sketch of the acceleration chain at the LHC The CMS Detector
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at the 6 / LHC31 Detection of Particles
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at the 7 / LHC31 The CMS Detector
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at the 8 / LHC31 3 Coordinate systems 4 Pseudorapidity 5 η-gaps.
6 Missing transverse momentum p/T
Some important concepts
In particle physics, a cross section (σ) 1 Cross Section represents the probability of production of 2 Luminosity a specific process. This quantity is related with the level of the interaction between the beam and the target, or between two beams, and it depends on the energy of collisions.
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at the 9 / LHC31 4 Pseudorapidity 5 η-gaps.
6 Missing transverse momentum p/T
Some important concepts
1 Cross Section 2 Luminosity N × N × f × F L ∼ A B (4) 3 Coordinate systems 4π(σA × σB ) Z L = Ldt (5)
Ni = σi × L (6)
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at the 9 / LHC31 5 η-gaps.
6 Missing transverse momentum p/T
Some important concepts
Y
Detector
1 Cross Section Punto de Z Dirección Colision del haz θ ϕ 2 Luminosity 3 Coordinate systems 4 Pseudorapidity
X Centro del LHC
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at the 9 / LHC31 6 Missing transverse momentum p/T
Some important concepts
h θ i η ≡ − ln tan . 2
1 Cross Section 2 Luminosity 3 Coordinate systems 4 Pseudorapidity 5 η-gaps.
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at the 9 / LHC31 Some important concepts
h θ i η ≡ − ln tan . 2
1 Cross Section 2 Luminosity 3 Coordinate systems 4 Pseudorapidity 5 η-gaps.
6 Missing transverse momentum p/T
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at the 9 / LHC31 Some important concepts
X T ~pi = 0, i
1 Cross Section X X = ~pT (visible) + ~pT (invisible) 2 Luminosity j k j k 3 Coordinate systems X X ~pT (invisible) = − ~pT (visible) 4 Pseudorapidity k j k j 5 η-gaps.
6 Missing transverse momentum p/T X T p/T = − ~pj (visible) (4) j
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at the 9 / LHC31 The algorithm uses the information from the different sub-detectors to reconstruct individual particle candidates: Muons, electrons, photons, charged and neutral hadrons. The reconstructed particles are then used to reconstruct more complicated objets such as jets (see next) and hadronic taus (τh), and to also to measure the p/T in the event.
Particle Flow Algorithm - CMS
The Particle Flow (PF) algorithm used by the CMS collaboration, has no precedent in the history of HEP.
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 10 the / LHC31 The reconstructed particles are then used to reconstruct more complicated objets such as jets (see next) and hadronic taus (τh), and to also to measure the p/T in the event.
Particle Flow Algorithm - CMS
The Particle Flow (PF) algorithm used by the CMS collaboration, has no precedent in the history of HEP. The algorithm uses the information from the different sub-detectors to reconstruct individual particle candidates: Muons, electrons, photons, charged and neutral hadrons.
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 10 the / LHC31 Particle Flow Algorithm - CMS
The Particle Flow (PF) algorithm used by the CMS collaboration, has no precedent in the history of HEP. The algorithm uses the information from the different sub-detectors to reconstruct individual particle candidates: Muons, electrons, photons, charged and neutral hadrons. The reconstructed particles are then used to reconstruct more complicated objets such as jets (see next) and hadronic taus (τh), and to also to measure the p/T in the event.
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 10 the / LHC31 Particle Flow Algorithm - CMS
The Particle Flow (PF) algorithm used by the CMS collaboration, has no precedent in the history of HEP. The algorithm uses the information from the different sub-detectors to reconstruct individual particle candidates: Muons, electrons, photons, charged and neutral hadrons. The reconstructed particles are then used to reconstruct more complicated objets such as jets (see next) and hadronic taus (τh), and to also to measure the p/T in the event.
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 10 the / LHC31 Particle Flow Algorithm - CMS
The Particle Flow (PF) algorithm used by the CMS collaboration, has no precedent in the history of HEP. The algorithm uses the information from the different sub-detectors to reconstruct individual particle candidates: Muons, electrons, photons, charged and neutral hadrons. The reconstructed particles are then used to reconstruct more complicated objets such as jets (see next) and hadronic taus (τh), and to also to measure the p/T in the event.
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 10 the / LHC31 2 Jet reconstruction
Some important concepts
1 Jet 1 Partonic 2 Hadronic 3 Detector
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 11 the / LHC31 Some important concepts
1 Jet 1 Partonic 2 Hadronic 3 Detector
2 Jet reconstruction
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 11 the / LHC31 Some important concepts
π − + Jet 1 − π Κ + Κ + π π 0
1 Jet 1 Partonic 2 Hadronic 3 Detector π − Vertice primario 2 Jet reconstruction π +
Κ +
π −
π 0 Jet 2
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 11 the / LHC31 Jet Reconstruction Algorithms
The identification of jets in collider experiments is very important. Cone-based reconstruction algorithms are of common use in particle physics. Determining the boundary of a cone for a reconstructed jet it is not a trivial problem, due to the repetitive branching nature of QCD radiation. There are two main classes of jet-reconstruction algorithms: 1 The iterative cone. 2 The sequential clustering, which includes the Kt and Anti−Kt algorithms.
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 12 the / LHC31 Important considerations
There are to important aspects that any jet algorithm must consider: The jet size and if the algorithm is infra-red and collinear(IRC) safe. The area of the cone enclosing the jet determine how much soft radiation is allowed. When a large jet radius is set, it allows to include enough particles from the hadronization process. Therefore, there is a good accuracy when the jet mass and energy are estimated. Nevertheless, with large jet radius, the jet mass and energy can often be overestimated due to Underlying Event (UE) and Pile-Up (PU) effects. The UE and PU effect can be reduced with a smaller jet radius.
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 13 the / LHC31 Reconstruction of Hadronic Tau Leptons
Taus (τ) are the heaviest known leptons: Mass 1.777 GeV. Because of their large mass, taus can decay both leptonically and hadronically.
The table shows the decay branching fraction for taus. Note that hadronic final states are the dominant decay modes : 64.8%.
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 14 the / LHC31 Electroweak SUSY Searches
Searches in the color sector have not yield positive signs of SUSY until now. SUSY searches in the electroweak (EWK) sector open a different avenue to find new physics: X Smaller predicted cross sections but lower levels of hadronic activity. X Complements the color searches.
The discovery of the Higgs opened a new set of SUSY searches: X Lightest neutral CP–even Higgs (h) expected to be SM–like, if others are heavy. X Would provide an indication for SUSY solution to hierarchy problem. X It can point to interesting models in compressed spectra scenarios.
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 15 the / LHC31 Particle Physics Cosmology
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 16 the / LHC31 Vector Boson Fusion Topology
The VBF topology is characterized by the presence of two highly energetic jets, with a large ∆η gap, located in oposite hemispheres of the detector, and with a large dijet reconstructed mass.
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 17 the / LHC31 Vector Boson Fusion Topology
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 18 the / LHC31 VBF SUSY at 8 TeV - Published in JHEP 1511 (2015) 189
8 final states considered. Did not look at soft lepton channels. Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 19 the / LHC31 VBF SUSY at 8 TeV - Published in PRL 118, 021802 (2017)
Andr´esFl´orez VectorVBF Boson to Invisible Fusion A final powerful state. tool to discoverJuly new 31, physics 2018 at 20 the / LHC31 VBF SUSY at 13 TeV
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 21 the / LHC31 Pheno.: VBF Heavy Neutrino - Phys.Lett. B778 (2018)
One of the open questions the SM fails to CMS and ATLAS searches assume address is the non-zero mass of the three that N` is lighter than VR: 0 mN` < mW ± and mN` < 0.5mZ . generations of neutrinos, which is implied by R the observation of neutrino oscillations. It has been suggested that because neutrinos can be their own anti-particles (Majorana fermions), the non-zero mass of light neutrinos ν` could be generated by a see-saw mechanism. For example, in the left-right symmetric model (LRSM), originally introduced to
Signal cross section as function of m(Nτ) explain the non-conservation of parity in 10
weak interactions within the SM, the (fb) Drell-Yan σ VBF introduction of a SU(2)R group, the 1 right-handed analogue of the SM SU(2)L group, produces three heavy right-handed
neutrino states N` (` = e, µ, τ) and three 10−1 ± 0 gauge bosons, VR = {WR ,Z }. ATLAS and CMS have a strong program to 10−2 1000 1200 1400 1600 1800 2000 2200 2400 search for N`. m(Nτ) [GeV] Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 22 the / LHC31 Phenomenology: VBF Heavy Neutrino
104 The phenomenological analysis was performed using tt-semileptonic 50 fb-1 3 m(N ) = 0.5 TeV two final states: µµjjj j and ττjjj j 10 µ f f f f m(Nµ) = 1.0 TeV
m(Nµ) = 1.5 TeV 102 Criterion τhτhjjjf jf µµjjjf jf Central Selections 10 |η(τh/µ)| < 2.1 < 2.5 1 plead(τ /µ) > 50 GeV > 50 GeV T h slead − p (τ /µ) > 20 GeV > 8 GeV 10 1 T h N(τ /µ) > 1 > 1 h −2 ∆R(τh1/µ1, τh2/µ2) > 0.3 > 0.3 10 |∆p (τ /µ , τ /µ )| > 50 GeV > 50 GeV T h1 1 h2 2 − 10 3 Q(τh1/µ1) × Q(τh2/µ2) > 0 > 0 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 Nb−jets = 0 = 0 MET ST [GeV] pcentral(j) 30 GeV 30 GeV T |ηcentral(j)| < 2.4 < 2.4 106 50 fb-1 N (j) = 2 = 2 5 DY→ll+jets central 10 W+jets
∆R(τ /µ, j) > 0.4 > 0.4 Events h tt-semileptonic VBF Selections 104 m(Nτ) = 0.5 TeV lead m(N ) = 1.0 TeV p (jet) 30 GeV 30 GeV 103 τ T m(Nτ) = 1.5 TeV lead |η (jet)| < 5.0 < 5.0 102 sub−lead p (jet) 30 GeV 30 GeV T 10 |ηsub−lead(jet)| < 5.0 < 5.0 1 ∆R(τh/µ, jet) > 0.4 > 0.4 η(j1) · η(j2) < 0 < 0 10−1 |∆η(j , j )| > 4.2 > 4.2 1 2 10−2 mjj > 750 GeV > 750 GeV −3 10 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
MET ST [GeV]
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 23 the / LHC31 Phenomenology: VBF Heavy Neutrino
The figures show the expected signal significance in the µµjjjf jf and τhτhjjjf jf channels, respectively, for integrated luminosities Lint = 50-1000 −1 2 fb and mixing |V`N` | = 1. −1 For Lint = 100 fb , the expected 95% exclusion on mNµ using the µµjjjf jf search channel is ∼ 1.7 TeV, while the 3σ (5σ) reach is ∼ 1.3 (1.0) TeV.
Similarly, the expected 95% exclusion on mNτ using the τhτhjjjf jf search −1 channel is ∼ 0.8 TeV at Lint = 100 fb .
102 102 -1 -1 LHC s = 13 TeV Lint = 50.0 fb LHC s = 13 TeV Lint = 50.0 fb L = 100.0 fb-1 L = 100.0 fb-1 µµ j j j j int τ τ j j j j int f f -1 h h f f -1 Lint = 500.0 fb Lint = 500.0 fb -1 -1 Lint = 1000.0 fb Lint = 1000.0 fb Significance Significance
10 10 5σ 5σ
3σ 3σ
1.69σ 1.69σ
1 1
1000 1500 2000 2500 3000 1000 1500 2000 2500 3000 m(Nµ) [GeV] m(Nτ) [GeV]
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 24 the / LHC31 VBF Heavy Neutrino
102 102 -1 -1 LHC s = 13 TeV Lint = 50.0 fb LHC s = 13 TeV Lint = 50.0 fb L = 100.0 fb-1 L = 100.0 fb-1 µµ j j j j int τ τ j j j j int f f -1 h h f f -1 Lint = 500.0 fb Lint = 500.0 fb -1 -1 Lint = 1000.0 fb Lint = 1000.0 fb Significance Significance
10 10 5σ 5σ
3σ 3σ
1.69σ 1.69σ
1 1
1000 1500 2000 2500 3000 1000 1500 2000 2500 3000 m(Nµ) [GeV] m(Nτ) [GeV]
102 µµ j j j j , |V |2=10-1 2 µ | LHC s = 13 TeV f f N 1.3 µ 2 -2 µ -1 µµ j j j j , |V | =10 N 2 -1 f f µN Lint = 1000.0 fb µ 2 -1 µ LHC s = 13 TeV τ τ |V | =10 h h j j j j , |Vτ | =10 -1 µN f f Nτ 2 -2 µ τ τ j j j j , |V | =10 Lint = 1000 fb h h τ 1.2 2 f f Nτ / |V |V | =1
2 µ N Significance | µ µ N µ 1.1 10 |V 5σ δ 1 3σ 1.69σ 0.9 1
0.8
0.7 1000 1500 2000 2500 3000 0.7 0.8 0.9 1 1.1 1.2 1.3 m(N) [GeV] δ m / m Nµ Nµ
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 25 the / LHC31 Pheno.: VBF Z’ - Phys.Lett. B767 (2017)
Another interesting idea, is the search of Z’ bosons through VBF production. So far, the LHC has search for Z’, assuming DY production, and mainly assuming SSM scenarios. Nevertheless, what happens if this particle does not couple to the color sector? We have studied different scenarios, assuming the couplings go as: gZ0qq = kq × gZqq, gZ0vv = kv × gZvv If the Z’ couples to vector bosons, its decay width is given by:
5 g 0 cosθ m Z vv ω Z0 192πm4 W The decay width can not be larger than the Z0 mass: max 0 2 gZ0vv = (5.3 × mW /mZ ) Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 26 the / LHC31 Phenomenology: VBF Z’
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 27 the / LHC31 3 VBF is perhaps of the best way to explore very compressed spectra region with taus, in SUSY scenarios, which has a direct connection to DM. 4 Other important applications of VBF have been proposed to search for heavy neutrinios of Z’ at the LHC. 5 The group at Uniandes is one of the main leaders of VBF searches at CMS and also has participated proposing new ideas to be explored at the LHC, from the phenological side.
Thank you!
Summary
Introduction. 1 The VBF topology is a power tool to search for new physics at the LHC. 2 The particular topology allows to reduce QCD multi-jet BGs significantly, while keeping great signal acceptance
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 28 the / LHC31 4 Other important applications of VBF have been proposed to search for heavy neutrinios of Z’ at the LHC. 5 The group at Uniandes is one of the main leaders of VBF searches at CMS and also has participated proposing new ideas to be explored at the LHC, from the phenological side.
Thank you!
Summary
Introduction. 1 The VBF topology is a power tool to search for new physics at the LHC. 2 The particular topology allows to reduce QCD multi-jet BGs significantly, while keeping great signal acceptance 3 VBF is perhaps of the best way to explore very compressed spectra region with taus, in SUSY scenarios, which has a direct connection to DM.
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 28 the / LHC31 5 The group at Uniandes is one of the main leaders of VBF searches at CMS and also has participated proposing new ideas to be explored at the LHC, from the phenological side.
Thank you!
Summary
Introduction. 1 The VBF topology is a power tool to search for new physics at the LHC. 2 The particular topology allows to reduce QCD multi-jet BGs significantly, while keeping great signal acceptance 3 VBF is perhaps of the best way to explore very compressed spectra region with taus, in SUSY scenarios, which has a direct connection to DM. 4 Other important applications of VBF have been proposed to search for heavy neutrinios of Z’ at the LHC.
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 28 the / LHC31 Thank you!
Summary
Introduction. 1 The VBF topology is a power tool to search for new physics at the LHC. 2 The particular topology allows to reduce QCD multi-jet BGs significantly, while keeping great signal acceptance 3 VBF is perhaps of the best way to explore very compressed spectra region with taus, in SUSY scenarios, which has a direct connection to DM. 4 Other important applications of VBF have been proposed to search for heavy neutrinios of Z’ at the LHC. 5 The group at Uniandes is one of the main leaders of VBF searches at CMS and also has participated proposing new ideas to be explored at the LHC, from the phenological side.
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 28 the / LHC31 Summary
Introduction. 1 The VBF topology is a power tool to search for new physics at the LHC. 2 The particular topology allows to reduce QCD multi-jet BGs significantly, while keeping great signal acceptance 3 VBF is perhaps of the best way to explore very compressed spectra region with taus, in SUSY scenarios, which has a direct connection to DM. 4 Other important applications of VBF have been proposed to search for heavy neutrinios of Z’ at the LHC. 5 The group at Uniandes is one of the main leaders of VBF searches at CMS and also has participated proposing new ideas to be explored at the LHC, from the phenological side.
Thank you!
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 28 the / LHC31 Summary
Introduction. 1 The VBF topology is a power tool to search for new physics at the LHC. 2 The particular topology allows to reduce QCD multi-jet BGs significantly, while keeping great signal acceptance 3 VBF is perhaps of the best way to explore very compressed spectra region with taus, in SUSY scenarios, which has a direct connection to DM. 4 Other important applications of VBF have been proposed to search for heavy neutrinios of Z’ at the LHC. 5 The group at Uniandes is one of the main leaders of VBF searches at CMS and also has participated proposing new ideas to be explored at the LHC, from the phenological side.
Thank you!
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 28 the / LHC31 Questions?
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 29 the / LHC31 Sources
http://iopscience.iop.org/article/10.1088/1748-0221/3/08/S08004/pdf http://cdsweb.cern.ch/record/1194487/files/PFT-09-001-pas.pdf http://iopscience.iop.org/article/10.1088/1742-6596/645/1/012008/pdf https://arxiv.org/pdf/1510.07488.pdf http://science.sciencemag.org/content/347/6226/1100/F1 https://www.quantumdiaries.org/2011/06/01/anatomy-of-a-jet-in-cms/ http://ed.fnal.gov/samplers/hsphys/old/activities%20old/top_quark_ stud_old.html
Andr´esFl´orez Vector Boson Fusion A powerful tool to discoverJuly new 31, physics 2018 at 30 the / LHC31