View
214
Download
2
Category
Preview:
Citation preview
Search for diboson resonances at CMS
identifying highly energetic boson decays and discriminating newphysics signals from the standardmodel background
Clemens Lange (CERN) DESY Physics Seminar
Hamburg/Zeuthen 31st May/1st June 2016
Clemens Lange - Diboson resonances searches at CMS31.05.2016
About diboson resonances
2
heavy resonances?
boson jets?
background estimation?
wasn’t there this diphoton
resonance?( )
[https://ideas.lego.com/projects/94885]
Clemens Lange - Diboson resonances searches at CMS31.05.2016
>how can we explain the big difference between the weak force and gravity?
>no symmetry in the standard model (SM) protects the Higgs mass
>µ|H2| always a singlet under phase transformations
> „natural“ explanation would be that SM is replaced by another theory at the TeV scale: µ2 ~ (heavier scale)2 ➜ new particles
> these theories could be:
>SUSY: protecting the Higgs mass by a symmetry
>Composite Higgs: the Higgs is not elementary
>Large/warped extra dimensions: gravity is strong at electroweak scale
We have a problem
3
µ2 = �v2 =�
g24M2
W ⇠ 104 GeV2 ⌧ MPl ⇠ 1038 GeV2
H H
t
t
31.05.2016 Clemens Lange - Diboson resonances searches at CMS
Composite Higgs?
> the Higgs could be non-fundamental
> instead: bound state of a new strong interaction
>e.g. size of 10-18 m ~ Fermi scale (100 GeV) ! light Higgs like a pion from a new sector
>solves hierarchy problem, and brings along new heavy particles/states
>heavy partners of SM particles decay to lighter ones (W, Z, H, top, …)
4
[https://www.learner.org/]
H H
t
t
31.05.2016 Clemens Lange - Diboson resonances searches at CMS
Why extra dimensions? RS1 Model
Original Randall-Sundrum (RS1) model o↵ers a solution to thehierarchy problem by postulating a 5
th space-time bounded by two(3 + 1)-dimensional branes.
Gravity is localized aty = 0, called the UV-
or Planck-brane.
Only gravity canpropagate through
‘bulk’.
SM particles reststrictedto y = ⇡R (IR- or TeV-brane).
Physical masses rescaledby e
�⇡kR: gravity is weak.
The resulting metric is nonfactorizable and depends on the radius yand curvature k
�1 of the extra dimension:
ds
2 = e
�2ky
⌘
µ⌫
dx
µ
dx
⌫ + dy
2; 0 y ⇡R
Therefore the RS warped geometry model proposes a solution to the‘hierarchy problem’ with reasonable values of kR ⇠ 11
Massive excited graviton modes (G⇤) are a defining featureE. Williams (Columbia U.) G⇤ ! WW ! `⌫jj thesis defense July 2nd, 2012 9 / 41
Large extra dimensions?
>another attempt to solve the hierarchy problem
>SM fields are confined to four-dimensional „membrane“, gravity propagates in additional dimensions
>effectively, change power law of gravity from to , where N = number of extra dimensions
> this only applies to particles with - smaller things have more possibilities to move
>„large“, because of size 1 mm to~1/TeV
>proposed by Arkani-Hamed, Dimopoulos, and Dvali (ADD)
5
Eric Williams
1/r2 1/r2+N
r ⌧ N
gravity gravity can propagatethrough bulk
bulk
Planck-brane TeV-brane
31.05.2016 Clemens Lange - Diboson resonances searches at CMS
Warped extra dimensions?
>often referred to as Randall-Sundrum (RS) models
>warping causes energy scale at one end of the extra dimension to be much larger than at the other end
>SM models reside on TeV-brane (in RS1 models)
>bulk graviton models allow SM particles into 5D-bulk
>overlap of 5-D profiles at TeV-brane (and Higgs) determine particle masses
>additionally, if distance between two branes is not fixed, additional fluctuations can occur
6
Eric Williams
Why extra dimensions? Bulk RS Model
Modern RS models (bulk RS) allow SM particles into 5-D bulk
Overlap of 5-D profiles at TeV brane (and the Higgs) determineparticles masses
Suppressed coupling to bosons and lightfermions; negligible rates to �� and ``
Enhanced coupling to heavy particles(t¯t,ZZ and WW ) motivates search in WW
channel!
G*! WW G*! ZZ G*! HH G*! gg G*! tT
E. Williams (Columbia U.) G⇤ ! WW ! `⌫jj thesis defense July 2nd, 2012 10 / 41
bulk
Why extra dimensions? RS1 Model
Original Randall-Sundrum (RS1) model o↵ers a solution to thehierarchy problem by postulating a 5
th space-time bounded by two(3 + 1)-dimensional branes.
Gravity is localized aty = 0, called the UV-
or Planck-brane.
Only gravity canpropagate through
‘bulk’.
SM particles reststrictedto y = ⇡R (IR- or TeV-brane).
Physical masses rescaledby e
�⇡kR: gravity is weak.
The resulting metric is nonfactorizable and depends on the radius yand curvature k
�1 of the extra dimension:
ds
2 = e
�2ky
⌘
µ⌫
dx
µ
dx
⌫ + dy
2; 0 y ⇡R
Therefore the RS warped geometry model proposes a solution to the‘hierarchy problem’ with reasonable values of kR ⇠ 11
Massive excited graviton modes (G⇤) are a defining featureE. Williams (Columbia U.) G⇤ ! WW ! `⌫jj thesis defense July 2nd, 2012 9 / 41
gravity gravity can propagatethrough bulk
bulk
Planck-brane TeV-brane
RS1 model
Bulk model
31.05.2016 Clemens Lange - Diboson resonances searches at CMS
How do we observe these models at the LHC?
>should be able to observe excitations/resonances/fluctuations
>composite Higgs: electroweak composite vector resonances !mostly spin-1 (W’, Z’)
! decay to pairs of W, Z, H
>Randall-Sundrum: Kaluza-Klein excitations of gravitons + radion fluctuations
>gravitons (spin-2): !RS1: decay predominantly to leptons
! bulk: decay to pairs of W, Z
!ADD: broader excess from many narrow-spaced resonances
>radions (spin-0): ! only used for signal modelling here
>focus here on narrow resonances (width < detector resolution), mass ≥ 600 GeV
7
1 Feynman diagrams
W 0W
H
q0
q
b
b
l
⌫
(a)
XW
W
g
g
q
q̄
l
⌫
(b)
g
g
g
q
q̄
c, b
c̄, b̄
(c)
Figure 1.1: Heavy X particle production and decay.
1
1 Feynman diagrams
W 0W
H
q0
q
b
b
l
⌫
(a)
XW
W
g
g
q
q̄
l
⌫
(b)
g
g
g
q
q̄
c, b
c̄, b̄
(c)
Figure 1.1: Heavy X particle production and decay.
1
Clemens Lange - Diboson resonances searches at CMS31.05.2016
What about the diphoton resonance?
>neutral resonance could be graviton or radion as in diboson searches
> resonance cannot directly couple to photons ➜ loop of charged particles (e.g. W, top, ?) in decay (and production?)
> there must be more than just a di-photon resonance
>searches presented in this talk constrain what physics models this potential resonance could be
8
31.05.2016 Clemens Lange - Diboson resonances searches at CMS
Reconstructing heavy resonances
>bosons will be very energetic ➜ collimated decay products
>need to develop dedicated reconstruction methods
>hadronic decays of bosons: ! „boson-tagging“
! exploiting substructure of jets
> leptonic decays: ! special isolation for dileptonic decays
! dedicated reconstruction algorithms for high-pT leptons
! new tau-identification algorithms
9
focus here on Run-2 developments and analyses
31.05.2016 Clemens Lange - Diboson resonances searches at CMS
Hadronic boson identification
>at CMS use anti-kT jet algorithm with R = 0.4
>already for resonances of 1 TeV a significant fraction of cases where the boson decay is contained in a single jet
> increase jet size to R = 0.8 to contain full decay within „fat“ jet
10
back of the envelope calculation:
for a resonance of mass 1 TeV the bosons from the decay will have pT~0.4 TeV ➜ ΔR ≈ 0.4
�Rqq ⇡ 2MV
pVT
JHEP 12 (2014) 017
5
but instead require that there is at least one AK5 b jet, with an angular distance of DR > 0.8 tothe CA8 jet considered as W jet candidate. To increase the statistical precision of the sample,we select the CA8 jet with the largest mass and with Df between the lepton and the jet greaterthan p/2 as W jet candidate, rather than the highest pT CA8 jet.
5 Algorithms for W jet identification
A jet clustering algorithm with R = 0.8 is used to identify W jets. A large value of R increasesthe efficiency to reconstruct W bosons with small boost as single jets, since the average angulardistance between the W decay products is inversely proportional to the pT of the W. The cho-sen value of R provides a high efficiency for W bosons with small boost and ensures that noefficiency is lost in the transition from classical W reconstruction from two small jets at low WpT and reconstruction from a single large jet at higher W pT (see e.g. Ref. [46]). Another pointto consider when choosing the value of R, is the tt data sample available for validating highlyboosted W jets. If R is chosen too large, the b quark from the t ! Wb decay tends to mergeinto the W jet. The chosen value of R is the result of a compromise between high efficiency forW bosons with small boost and a sufficiently large sample of W jets in tt data for validating theW jet identification algorithms.
(GeV)T
W boson p200 400 600 800 1000 1200
Rec
onst
ruct
ion
effic
ienc
y
0
0.2
0.4
0.6
0.8
1
Merged jet efficiency
single CA R=0.8 jet
R (W,jet) < 0.1∆
Resolved jets efficiency
two AK R=0.5 jets
) < 0.1j
,jeti
R (q∆
8 TeV
CMSSimulation
Figure 1: Efficiency to reconstruct a CA8 jet within DR < 0.1 of a generated W boson, and theefficiency to reconstruct two AK5 jets within DR < 0.1 of the generated quarks from longitudi-nally polarized W bosons, as a function of the pT of the W boson.
Figure 1 shows the pT range of W bosons for which the R = 0.8 algorithm is efficient andcompares this to the efficiency for reconstructing W bosons from two R = 0.5 jets. Above apT of 200 GeV, the CA8 jet algorithm, used to identify W jets, becomes more efficient than thereconstruction of a W boson from two AK5 jets. In this paper we therefore study substructureobservables to identify W jets for an R = 0.8 algorithm. Whether an AK or a CA algorithmis used in such comparison does not affect the overall conclusion. The choice of CA (withR = 0.8) and AK (R = 0.5) is simply due to their wide use in CMS publications, where CAwas introduced in the first top tagging algorithm paper of CMS [47]. Whenever we refer toefficiency (e) in this paper, we refer to the full efficiency to identify a W boson relative to allgenerated W bosons decaying to hadrons.
�R =p
�⌘2 +��2
Clemens Lange - Diboson resonances searches at CMS31.05.2016
CMS particle flow reconstruction
> tracking detectors and calorimeters contained in magnetic field
>particle flow algorithm makes use of sub-detectors with best resolution (both spatial and energy)
>actual „particles“ enter jet clustering
11
31.05.2016 Clemens Lange - Diboson resonances searches at CMS
Jet pruning
>we know the masses of W, Z and Higgs very well ➜ can use them as constraints
>however, large number of particles in jet ➜ rather bad resolution
> jet pruning (generally grooming) removes soft and large angle radiation
>strategy: ! recluster jet using Cambridge-Aachen
(CA) jet algorithm
12
?pruned jet mass
0 50 100 150
arb
itra
ry u
nits
0
0.1
0.2
SM Higgs, m = 600 GeV
ungroomed jet mass
W+Jets, MadGraph+Pythia6
ungroomed jet mass
CMS Simulation
CMS-PAS-HIG-14-008
31.05.2016 Clemens Lange - Diboson resonances searches at CMS
Reminder: jet clustering algorithms
>kT-algorithms: sequential clustering
>examine four-vector inputs pairwiseand construct jets hierarchically
>anti-kT: preferentially merge constituents with high pT with respect to their nearest neighbours first
>Cambridge-Aachen: no pT-weighting, merge based on spatial separation only ➜ undoing clustering yields subjets
13
JHEP 0804:063,2008
31.05.2016 Clemens Lange - Diboson resonances searches at CMS
Jet pruning
>we know the masses of W, Z and Higgs very well ➜ can use them as constraints
>however, large number of particles in jet ➜ rather bad resolution
> jet pruning (generally grooming) removes soft and large angle radiation
>strategy: ! recluster jet using Cambridge-Aachen
(CA) jet algorithm
! „soft“:
! „large angle“: , orig = unpruned CA jet
>cut on mass window (~±10 GeV)
14
min(piT , pjT )/p̃T < 1
�Rij > morig/porigTPruned mass [GeV]
0 50 100 150 200 250 300Ev
ents
/ 5.
00 G
eV0
100
200
300
400
500
310×
CMS Data
WW (MADGRAPH))→ (2 TeV) Bulk
W (G
ZZ(MADGRAPH))→ (2 TeV) Bulk
Z (G WZ (MADGRAPH))→W (W' (2 TeV)
QCD PYTHIA8
(13 TeV)-12.6 fb
CMSPreliminary
Pruned mass [GeV]0 50 100 150 200 250 300
MC
Dat
a
0.5
1
1.5
CMS-PAS-EXO-15-002
Clemens Lange - Diboson resonances searches at CMS31.05.2016
N-subjettiness
> for boson-tagging: want to quantify how 2-subjetty a jet is
>➜ to what extent is energy flow aligned along 2 momentum directions (N=2)?
15
JHEP 1103:015,2011
(a)
−0.2 0 0.2 0.4 0.6 0.8 1
1
1.2
1.4
1.6
1.8
2
2.2Boosted W Jet, R = 0.6
η
φ
(b)
(c)
−1.2 −1 −0.8 −0.6 −0.4 −0.2
4.6
4.8
5
5.2
5.4
5.6
5.8Boosted QCD Jet, R = 0.6
η
φ
(d)
Figure 1: Left: Schematic of the fully hadronic decay sequences in (a) W+W− and (c) dijet QCDevents. Whereas a W jet is typically composed of two distinct lobes of energy, a QCD jet acquiresinvariant mass through multiple splittings. Right: Typical event displays for (b) W jets and (d)QCD jets with invariant mass near mW . The jets are clustered with the anti-kT jet algorithm [31]using R = 0.6, with the dashed line giving the approximate boundary of the jet. The marker sizefor each calorimeter cell is proportional to the logarithm of the particle energies in the cell. Thecells are colored according to how the exclusive kT algorithm divides the cells into two candidatesubjets. The open square indicates the total jet direction and the open circles indicate the twosubjet directions. The discriminating variable τ2/τ1 measures the relative alignment of the jetenergy along the open circles compared to the open square.
with τN ≈ 0 have all their radiation aligned with the candidate subjet directions and
therefore have N (or fewer) subjets. Jets with τN ≫ 0 have a large fraction of their energy
distributed away from the candidate subjet directions and therefore have at least N + 1
subjets. Plots of τ1 and τ2 comparing W jets and QCD jets are shown in Fig. 2.
Less obvious is how best to use τN for identifying boosted W bosons. While one might
naively expect that an event with small τ2 would be more likely to be a W jet, observe that
QCD jet can also have small τ2, as shown in Fig. 2(b). Similarly, though W jets are likely
– 4 –
(a)
−0.2 0 0.2 0.4 0.6 0.8 1
1
1.2
1.4
1.6
1.8
2
2.2Boosted W Jet, R = 0.6
η
φ
(b)
(c)
−1.2 −1 −0.8 −0.6 −0.4 −0.2
4.6
4.8
5
5.2
5.4
5.6
5.8Boosted QCD Jet, R = 0.6
η
φ
(d)
Figure 1: Left: Schematic of the fully hadronic decay sequences in (a) W+W− and (c) dijet QCDevents. Whereas a W jet is typically composed of two distinct lobes of energy, a QCD jet acquiresinvariant mass through multiple splittings. Right: Typical event displays for (b) W jets and (d)QCD jets with invariant mass near mW . The jets are clustered with the anti-kT jet algorithm [31]using R = 0.6, with the dashed line giving the approximate boundary of the jet. The marker sizefor each calorimeter cell is proportional to the logarithm of the particle energies in the cell. Thecells are colored according to how the exclusive kT algorithm divides the cells into two candidatesubjets. The open square indicates the total jet direction and the open circles indicate the twosubjet directions. The discriminating variable τ2/τ1 measures the relative alignment of the jetenergy along the open circles compared to the open square.
with τN ≈ 0 have all their radiation aligned with the candidate subjet directions and
therefore have N (or fewer) subjets. Jets with τN ≫ 0 have a large fraction of their energy
distributed away from the candidate subjet directions and therefore have at least N + 1
subjets. Plots of τ1 and τ2 comparing W jets and QCD jets are shown in Fig. 2.
Less obvious is how best to use τN for identifying boosted W bosons. While one might
naively expect that an event with small τ2 would be more likely to be a W jet, observe that
QCD jet can also have small τ2, as shown in Fig. 2(b). Similarly, though W jets are likely
– 4 –
(a)
−0.2 0 0.2 0.4 0.6 0.8 1
1
1.2
1.4
1.6
1.8
2
2.2Boosted W Jet, R = 0.6
η
φ
(b)
(c)
−1.2 −1 −0.8 −0.6 −0.4 −0.2
4.6
4.8
5
5.2
5.4
5.6
5.8Boosted QCD Jet, R = 0.6
η
φ
(d)
Figure 1: Left: Schematic of the fully hadronic decay sequences in (a) W+W− and (c) dijet QCDevents. Whereas a W jet is typically composed of two distinct lobes of energy, a QCD jet acquiresinvariant mass through multiple splittings. Right: Typical event displays for (b) W jets and (d)QCD jets with invariant mass near mW . The jets are clustered with the anti-kT jet algorithm [31]using R = 0.6, with the dashed line giving the approximate boundary of the jet. The marker sizefor each calorimeter cell is proportional to the logarithm of the particle energies in the cell. Thecells are colored according to how the exclusive kT algorithm divides the cells into two candidatesubjets. The open square indicates the total jet direction and the open circles indicate the twosubjet directions. The discriminating variable τ2/τ1 measures the relative alignment of the jetenergy along the open circles compared to the open square.
with τN ≈ 0 have all their radiation aligned with the candidate subjet directions and
therefore have N (or fewer) subjets. Jets with τN ≫ 0 have a large fraction of their energy
distributed away from the candidate subjet directions and therefore have at least N + 1
subjets. Plots of τ1 and τ2 comparing W jets and QCD jets are shown in Fig. 2.
Less obvious is how best to use τN for identifying boosted W bosons. While one might
naively expect that an event with small τ2 would be more likely to be a W jet, observe that
QCD jet can also have small τ2, as shown in Fig. 2(b). Similarly, though W jets are likely
– 4 –
(a)
−0.2 0 0.2 0.4 0.6 0.8 1
1
1.2
1.4
1.6
1.8
2
2.2Boosted W Jet, R = 0.6
η
φ
(b)
(c)
−1.2 −1 −0.8 −0.6 −0.4 −0.2
4.6
4.8
5
5.2
5.4
5.6
5.8Boosted QCD Jet, R = 0.6
η
φ
(d)
Figure 1: Left: Schematic of the fully hadronic decay sequences in (a) W+W− and (c) dijet QCDevents. Whereas a W jet is typically composed of two distinct lobes of energy, a QCD jet acquiresinvariant mass through multiple splittings. Right: Typical event displays for (b) W jets and (d)QCD jets with invariant mass near mW . The jets are clustered with the anti-kT jet algorithm [31]using R = 0.6, with the dashed line giving the approximate boundary of the jet. The marker sizefor each calorimeter cell is proportional to the logarithm of the particle energies in the cell. Thecells are colored according to how the exclusive kT algorithm divides the cells into two candidatesubjets. The open square indicates the total jet direction and the open circles indicate the twosubjet directions. The discriminating variable τ2/τ1 measures the relative alignment of the jetenergy along the open circles compared to the open square.
with τN ≈ 0 have all their radiation aligned with the candidate subjet directions and
therefore have N (or fewer) subjets. Jets with τN ≫ 0 have a large fraction of their energy
distributed away from the candidate subjet directions and therefore have at least N + 1
subjets. Plots of τ1 and τ2 comparing W jets and QCD jets are shown in Fig. 2.
Less obvious is how best to use τN for identifying boosted W bosons. While one might
naively expect that an event with small τ2 would be more likely to be a W jet, observe that
QCD jet can also have small τ2, as shown in Fig. 2(b). Similarly, though W jets are likely
– 4 –
W-jet QCD-jet
normalisation sum over particles minimise distance to candidate subjets
⌧N =1
d0
X
k
pT,k min(�R1,k,�R2,k, ...,�RN,k)
1 axis2 axes
low values of τN ➜ compatibility with the hypothesis of N axes
31.05.2016 Clemens Lange - Diboson resonances searches at CMS
N-subjettiness ratio
>bare τN has very little discrimination power
>take ratio τ2/τ1 instead
>mind: rather complicated variable, difficult to model ➜ need to validate in data
>clean sample of W-jets: top-antitop quark pairs used for calibration
16
21τ0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Even
ts /
0.05
2000
4000
6000
8000
10000
12000
14000CMS Data
WW (MADGRAPH)→ (2 TeV) BulkG
ZZ(MADGRAPH)→ (2 TeV) BulkG WZ (MADGRAPH)→W' (2 TeV)
QCD PYTHIA8
< 105 GeVP65 GeV < M
(13 TeV)-12.6 fb
CMSPreliminary
21τ0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
MC
Dat
a
0.5
1
1.5
CMS-PAS-EXO-15-002
Even
ts /
( 0.0
4 )
0
50
100
150
200
250
300
350 CMS Data tt
Single Top VV
W+jets MC Stat
Wprime1TeV x 50
(13 TeV)-12.2 fb
CMSPreliminary
(13 TeV)-12.2 fb
CMSPreliminary
1τ/2τ0 0.2 0.4 0.6 0.8 1
Dat
a / M
C
0.5
1
1.5
2
31.05.2016 Clemens Lange - Diboson resonances searches at CMS
Higgs➜bb tagging
>Higgs has higher mass than W/Z bosons ➜ τ2/τ1 less important, exploit b-jet content instead
> two different strategies: ! identify b-subjets
! tag fat jet
>currently, both show comparable performance
>50% lower mis-tagging rate than W-/Z-tagging
>dedicated Higgs-tagger available soon
17
EXO-14-009
(GeV)jJet mass m0 50 100 150 200
Arbi
trary
sca
le
0
0.1
0.2
0.3
0.4q/g MADGRAPH+PYTHIA
q'bq → Wb →t b b→H
4q→ WW* →H q'q →W q q→Z
CA pruned R=0.8
CMSSimulation
8 TeV
CMS DP-2015/038
H➜WW➜qqqq tagging is done using τ4/τ2 ratio
(cf. τ2/τ1 for W/Z)
31.05.2016 Clemens Lange - Diboson resonances searches at CMS
Higgs➜ττ tagging
>τ-lepton can decay hadronically and leptonically
>need to take into account potential overlap between the two τ-leptons ! remove tracks/particles entering other
isolation cone
>discrimination against q-/g-jets: MVA-based isolation ! sum reconstructed particle energies in
various cones around τ decay products
>neutrinos in decay cannot be reconstructed ➜ missing energy ! ττ-reconstruction using templates from
Monte Carlo simulation (SVfit)
18
CMS-PAS-EXO-15-008
b-tagged untaggedν
!
!
H
μ ν
ν
π
h
CMS Preliminary (8 TeV)-119.7 fb
) [GeV]τ,τM(20 40 60 80 100 120 140 160 180 200 220 240
Even
ts /
10 G
eV
5
10
15
20
25
30
35 Drell-Yan + jetstt
W + jetsSingle topDibosonQCD multijets
=1)RΛ=1.5 TeV, X
30 (M×Signal Observed
currently only 8 TeV results
31.05.2016 Clemens Lange - Diboson resonances searches at CMS
Lepton (muon + electron) reconstruction
> two isolation issues: ! radiation from highly energetic leptons
spoils isolation
! leptons spoil each other’s isolation
>employ dedicated high-pT algorithms to preserve high efficiency
> loosen selection criteria one of the leptons in Z➜ll decays
> leptonic W-decay: need to recover z-component of neutrino ! use W-mass constraint for reconstruction
19
Effic
ienc
y
0.75
0.8
0.85
0.9
0.95
1
>35 GeVT
Barrel, E
-1 L dt = 19.6 fb∫ = 8 TeV, sCMS Preliminary,
DATA (BG subtracted)
DY (MC)
(GeV)TE40 50 60 70 100 200 300 400 500 1000
Scal
e Fa
ctor
0.90.920.940.960.98
11.021.041.061.08
1.1
High energy electron ID (HEEP)
CMS DP-2013/003
Clemens Lange - Diboson resonances searches at CMS31.05.2016
Strategy/event selection for VV analyses
20
VV ➜ qqqq analysis VW ➜ qqlν analysis VZ ➜ qqll analysis
trigger HT trigger (800 GeV)or jet+groomed mass single lepton trigger (e/µ pT > 105/45 GeV)
lepton(s) — HEEP e/high-pT µ special iso/ID for2nd lepton
V-jetanti-kT R=0.8, pT > 200 GeV,exploit substructure τ2/τ1, use groomed mass
V boson candidate(s)
Δη < 1.3 reconstruct leptonic V, pT > 200 GeV use mass window
Xreconstruct X using both reconstructed vector bosons
search for bump in mVV distribution
Models and final states
• Looking for mass>~600 GeV VV/VH/HH resonances • Models of extra dimensions
• KK-Graviton G ! WW/ZZ/HH, Radion R ! WW/ZZ/HH • Bulk graviton model prefers di-boson decays,
while classical Randall-Sundrum model prefers di-fermion decays • Models of compositeness, new forces
• W’ ! WZ/WH, Z’ ! WW/ZH, Technicolor ρTC ! WZ • Composite Higgs, Little Higgs model prefer di-boson decays,
while sequential standard model prefers di-fermion decays • Generalized models of heavy vector triplets (HVT) consisting of X± and X0
• Bosons get high (pT>~200 GeV) boost • special reconstruction techniques
for jets and taus • special isolation techniques for leptons
3 4 Nov 2014 Andreas Hinzmann
G
W
W
g
g
q
q
⌫
`
More from Jen, Alexandra
More from Nhan, Dinko, Cesar, Aniello
X
additional cuts on separation of bosons in Δɸ and ΔR
31.05.2016 Clemens Lange - Diboson resonances searches at CMS
Dijet (VV) analysis
>trigger at ~100% efficiency at mJJ > 1 TeV ! apply cut on reconstructed dijet system
>define different τ2/τ1 regions: ! high purity to suppress background
! low purity to recover signal efficiency at high masses
>split W and Z samples based on pruned jet mass (65-85, 85-105 GeV)
>still dominated by QCD multi-jet events
>difficult to obtain sufficient MC simulation statistics
>need a data-driven approach
>exponentially falling spectrum: use fit function
21
21τ0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Even
ts /
0.05
2000
4000
6000
8000
10000
12000
14000CMS Data
WW (MADGRAPH)→ (2 TeV) BulkG
ZZ(MADGRAPH)→ (2 TeV) BulkG WZ (MADGRAPH)→W' (2 TeV)
QCD PYTHIA8
< 105 GeVP65 GeV < M
(13 TeV)-12.6 fb
CMSPreliminary
21τ0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
MC
Dat
a
0.5
1
1.5
CMS-PAS-EXO-15-002
HP
LP
31.05.2016 Clemens Lange - Diboson resonances searches at CMS
VV background estimation
>naively, fitting the mJJ spectrum could swallow signal
>also, need to avoid claiming false discovery (in particular in tail)
>fit function:
>number of free parameters determined byF-test: ! check if quality of fit improves by > 10% confidence
level
! if not, stick with current fit function
>extensive bias tests conducted
>combined signal+background fit performed
22
Dijet invariant mass [GeV]1000 1500 2000 2500 3000 3500
Even
ts /
94.7
GeV
-110
1
10
210
310
410CMS data
2 par. background fit
= 0.014 pb)σWW (→G(2 TeV)
WW, low-purity > 200 GeV
T| < 2.4, pη|
| < 1.3jjη∆ > 1 TeV, |jjM
(13 TeV)-12.6 fb
CMSPreliminary
Dijet invariant mass [GeV]1000 1500 2000 2500 3000 3500
σD
ata-
Fit
-3-2-10123
or
2 parameters 3 parameters
CMS-PAS-EXO-15-002
very similar background estimation strategy as for
diphoton resonance search
Clemens Lange - Diboson resonances searches at CMS31.05.2016
Intermezzo: Zɣ search overview
> recently published Z➜ll + ɣ search
> inspired by ɣɣ „excess“
>same photon ID as ɣɣ search, dilepton ID as in ZV search, fit background
> limited by statistics, no significant excess
23
CMS-PAS-EXO-16-019
Even
ts /
( 20
GeV
)
1
10
Data
Fit
Uncertainty
) [GeV]γ-e+M(e200 400 600 800 1000 1200 1400
stat
σ(d
ata-
fit)/
2−1−012
(13 TeV)-12.7 fbCMS Preliminary
Even
ts /
( 20
GeV
)
1
10
210Data
Fit
Uncertainty
) [GeV]γ-µ+µM(200 400 600 800 1000 1200 1400
stat
σ(d
ata-
fit)/
2−1−012
(13 TeV)-12.7 fbCMS Preliminary
electron channelmuon channel
31.05.2016 Clemens Lange - Diboson resonances searches at CMS
VW/VZ analysis overview
>for 2015 data, two separate analyses performed: ! „low mass“: 600-1000 GeV
! „high mass“: 1-4 TeV
!VZ analysis not yet public
>difference low vs. high mass: ! lower boost ➜ can use isolated lepton
triggers with 27 GeV thresholds
>requiring an isolated lepton suppresses QCD multi-jet background significantly
>dominant backgrounds: !Drell-Yan/W+Jets
! top-antitop quark production
>can estimate individual background components from sidebands
24
Even
ts /
( 20
)
0
0.20.4
0.60.8
11.2
1.41.6
1.8
310×CMS Data W+jets
VV tt
Single Top MC Stat
Wprime1TeV x 50
(13 TeV)-12.2 fb
CMSPreliminary
(13 TeV)-12.2 fb
CMSPreliminary
(GeV)AK8pT100 200 300 400 500 600 700
Dat
a / M
C
0.5
1
1.5
2
CMS-PAS-B2G-16-004
31.05.2016 Clemens Lange - Diboson resonances searches at CMS
VW analysis background estimation
>statistics in MC simulated samples still limited
> furthermore, analysis performed in extreme phase space
>use pruned mass sidebands (40-65 GeV, 135-160 GeV) to exploit correlation between pruned jet mass and resonance mass ! Higgs mass region kept blind
>determine ratio of simulated to data distributions in sideband
>extrapolate to signal region using transfer function (based on simulation)
>method accounts for data-MC differences in shape and normalisation
25
CMS-PAS-B2G-16-004CMS-PAS-EXO-15-002
Pruned jet mass (GeV)40 60 80 100 120 140
data
σD
ata-
Fit
-202
Even
ts /
( 5 G
eV )
50
100
150
200
250
300
350
→ signal region ←
WWenriched
WZenriched
High-Purity
νµCMS Data W+jets
WW/WZ ttSingle Top Uncertainty
(13 TeV)-12.2 fb
CMSPreliminary
(GeV)WVM1 1.5 2 2.5 3 3.5 4
310×
data
σD
ata-
Fit
-202
Even
ts /
( 100
GeV
)-210
-110
1
10
210
310
410 νCMS Data e W+jets
WW/WZ ttSingle Top Uncertainty
100)×=2 TeV (G MBulkGHigh-Purity, WW enriched
(13 TeV)-12.2 fb
CMSPreliminary
Higgs
Clemens Lange - Diboson resonances searches at CMS31.05.2016
Intermezzo: ɣɣ vs. Zɣ vs. WW
> limits for narrow resonances ! caveat: slightly different models used
>minimal upward fluctuations?
26
CM
S-PA
S-E
XO
-15-004
CM
S-PA
S-B
2G-16-004
CM
S-PA
S-E
XO
-16-019
Resonance Mass [GeV]400 600 800 1000 1200 1400 1600 1800 2000
) [fb
]γZ
→ B
R(A
× σ
95%
CL
UL
on
0
50
100
150
200
250
300
W = 0.014%
Observed
σ 1±Expected
σ 2±Expected
(13 TeV)-1 2.7 fbCMS Preliminary
(GeV)GM600 700 800 900 1000
WW
)(pb)
→ Bu
lk x
BR
(G95
%σ
-310
-210
-110
1
10
210 (13 TeV)-12.3 fb
CMSPreliminary Expected
SAsympt. CL
1 s.d.± Expected S
Asympt. CL 2 s.d.± Expected
SAsympt. CL
, k = 0.5 WW→BulkG BR× THσ
ObservedS
Asympt. CL
ν l→W
ɣɣ
Zɣ
WW
Clemens Lange - Diboson resonances searches at CMS31.05.2016
VH analysis overview
>2015 data: H➜bb, leptonic W/Z decays !W➜lν
! Z➜ll
! Z➜νν
>categorise in single and double subjet b-tag categories
>same background estimation method as for VW search
27
CMS-PAS-B2G-16-003
jet pruned mass (GeV)50 100 150 200 250 300
Even
ts /
5.0
GeV
0
5
10
15
20
25
30
35
40
45 (13 TeV)-12.17 fb
CMSPreliminary
)bbνν,ν (ll,l→ Vh →X
0l, 1 b-tag
LSB VV Higgs HSB
DataV+jetsTop, STVV, VHBkg. unc.
jet pruned mass (GeV)50 100 150 200 250 300
Pulls
4−2−024
(GeV)VhTm
1000 1500 2000 2500 3000
Even
ts /
100.
0 G
eV2−10
1−10
1
10
210
(13 TeV)-12.17 fb
CMSPreliminary
)bbνν,ν (ll,l→ Vh →X
0l, 1 b-tag
DataV+jetsTop, STVV, VHBkg. unc.
=2000 GeVXmHVT model B
(GeV)VhTm
1000 1500 2000 2500 3000
Pulls
4−2−024
Z➜νν, 1 b-tag
31.05.2016 Clemens Lange - Diboson resonances searches at CMS
Signal modelling and uncertainties
>depending on spin of new particles, polarisation of bosons different
>Bulk graviton (spin-2) and W’/Z’ (spin-1) models primarily couple to longitudinal components of W/Z
>analytical description of signal shapes based on fully simulated benchmark mass points ! double-sided Crystal-Ball function
! linearly interpolation between benchmark points
>signal efficiency up to 15% depending on analysis category
> largest uncertainties: ! background estimation
! jet energy and mass scale
! boson-tagging
28
(GeV)Vhm0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
Arbi
trary
uni
ts0
0.1
0.2
0.3
0.4
0.5
0.6
0.7 CMSSimulation Preliminary
)bbνν,ν (ll,l→ Vh →X
channelµ2
13 TeV
=800 GeVXm=1000 GeVXm=1200 GeVXm=1400 GeVXm=1600 GeVXm=1800 GeVXm=2000 GeVXm=2500 GeVXm=3000 GeVXm=3500 GeVXm=4000 GeVXm
CMS-PAS-B2G-16-003
Z➜µµ, ≥1 b-tag
31.05.2016 Clemens Lange - Diboson resonances searches at CMS
Model interpretation
>several different analyses performed
>advantageous to use common benchmark models for easier interpretation
>need to know individual couplings to bosons ! individual analysis: e.g. σ(gg➜G➜WW)
! combination: e.g. σ(gg➜G)
!mind also production mechanism
29
arXiv:1404.0102
are transverse (see for example [63]). The kk-graviton coupling to bulk weab bosons alsoexperience the dg volume suppression.
Decays
On figure (V.4) we show the kk-graviton branching fractions to SM particles, the leftpart of this figure shows the kk-graviton branching ratios on bulk scenario, assumingthe elementary top scenario. The right part shows kk-graviton branching ratios on RS1scenario.
On this figure we clearly note the couplings of RS1 kk-graviton with SM particlesare democratic with respect to the number of degree of freedom of each field, while thecouplings of bulk kk-graviton with SM particles are predominantly to the fields localizedon TeV brane (massive bosons and higgs field).
The highest branching fraction of a RS1 kk-graviton is to di-jet final states (gg +qq̄).The di-photon channel would also be a good search channel on this scenario, by itscleanness and non negligible branching ratio.
For the bulk kk-graviton case the highest branching fractions are to massive states,heavy di-bosons and top quarks (on the elementary top scenario). On the case of atrans-TeV resonance, each one of the di-bosons products are boosted and consequentlyits sub-products collimated. The development of substructure techniques make from thehadronic di-boson channels golden channels on bulk kk-graviton search.
200 400 600 800 1000 1200 140010- 4
0.001
0.01
0.1
1
MGr H GeVL
GHGe
VL
Bulk
tt
gg
aa
hh
WW
ZZ
200 400 600 800 1000 1200 140010- 4
0.001
0.01
0.1
1
MGr H GeVL
GHGe
VL
RS1
nn
ll
tt
gg
aa
hh
WW
ZZ
Figure V.4: KK-graviton branching fractions. Left: Bulk scenario, assuming elementary topquark. Right RS1 scenario. The dashed line represents the individual RS1 kk-graviton decayrates to a pair of light fermions ff̄ , where f represents both light quarks (u, d, s, c, b) or leptons(e, µ, ⌧). – Branching ratios are independent of k parameter.
Figure (V.5) shows a zoom of kk-graviton branching ratios comparing two distinctscenarios for third family WED embedding: The thick curves considers a fully elementarytop quark [60] while thin dashed ones we ignores kk-graviton coupling with top quark.It is not a surprise to note that kk-graviton branching ratios to bosons pais (W/Z/H)increases when there is not kk-graviton coupling to top quark.
On figure (V.6) we see the total width on RS1 scenario the kk-graviton is around twoorders of magnitude bigger than on bulk scenario, given the same geometric parameters.The experimental resolution on the width of the resonance depends on the investigated
18
are transverse (see for example [63]). The kk-graviton coupling to bulk weab bosons alsoexperience the dg volume suppression.
Decays
On figure (V.4) we show the kk-graviton branching fractions to SM particles, the leftpart of this figure shows the kk-graviton branching ratios on bulk scenario, assumingthe elementary top scenario. The right part shows kk-graviton branching ratios on RS1scenario.
On this figure we clearly note the couplings of RS1 kk-graviton with SM particlesare democratic with respect to the number of degree of freedom of each field, while thecouplings of bulk kk-graviton with SM particles are predominantly to the fields localizedon TeV brane (massive bosons and higgs field).
The highest branching fraction of a RS1 kk-graviton is to di-jet final states (gg +qq̄).The di-photon channel would also be a good search channel on this scenario, by itscleanness and non negligible branching ratio.
For the bulk kk-graviton case the highest branching fractions are to massive states,heavy di-bosons and top quarks (on the elementary top scenario). On the case of atrans-TeV resonance, each one of the di-bosons products are boosted and consequentlyits sub-products collimated. The development of substructure techniques make from thehadronic di-boson channels golden channels on bulk kk-graviton search.
200 400 600 800 1000 1200 140010- 4
0.001
0.01
0.1
1
MGr H GeVL
GHGe
VL
Bulk
tt
gg
aa
hh
WW
ZZ
200 400 600 800 1000 1200 140010- 4
0.001
0.01
0.1
1
MGr H GeVL
GHGe
VL
RS1
nn
ll
tt
gg
aa
hh
WW
ZZ
Figure V.4: KK-graviton branching fractions. Left: Bulk scenario, assuming elementary topquark. Right RS1 scenario. The dashed line represents the individual RS1 kk-graviton decayrates to a pair of light fermions ff̄ , where f represents both light quarks (u, d, s, c, b) or leptons(e, µ, ⌧). – Branching ratios are independent of k parameter.
Figure (V.5) shows a zoom of kk-graviton branching ratios comparing two distinctscenarios for third family WED embedding: The thick curves considers a fully elementarytop quark [60] while thin dashed ones we ignores kk-graviton coupling with top quark.It is not a surprise to note that kk-graviton branching ratios to bosons pais (W/Z/H)increases when there is not kk-graviton coupling to top quark.
On figure (V.6) we see the total width on RS1 scenario the kk-graviton is around twoorders of magnitude bigger than on bulk scenario, given the same geometric parameters.The experimental resolution on the width of the resonance depends on the investigated
18
1 Feynman diagrams
W 0W
H
q0
q
b
b
l
⌫
(a)
XW
W
g
g
q
q̄
l
⌫
(b)
g
g
g
q
q̄
c, b
c̄, b̄
(c)
Figure 1.1: Heavy X particle production and decay.
1
31.05.2016 Clemens Lange - Diboson resonances searches at CMS
Model tuning
>models described before can be tuned by a handful of parameters
>bulk graviton: !mass of graviton
! coupling constant determining production cross section and width
>heavy vector triplet (HVT): ! phenomenological Lagrangian
! describes production and decay of heavy spin-1 resonances
! 4 parameters for resonance mass, interaction strength, couplings to bosons and fermions
! focus here on „Model B“ with enhanced couplings to bosons
30
500 1000 1500 2000 2500 3000 3500 4000
0.02
0.04
0.06
0.08
0.10
0.12
M0 @GeVD
BRHV0Æ2XL W+W-
Zhuudd
llè
nnbbttè
gV = 1
Model A
500 1000 1500 2000 2500 3000 3500 4000
10-3
10-2
10-1
M0 @GeVD
BRHV0Æ2XL W+W-
Zhuudd
llè
nnbbttè
gV = 3
Model B
500 1000 1500 2000 2500 3000 3500 4000100
101
102
M0 @GeVD
GHV0Æ2XL@G
eVD gV = 1
gV = 2gV = 3
Model A
500 1000 1500 2000 2500 3000 3500 4000
102
103
M0 @GeVD
GHV0Æ2XL@G
eVD
gV = 3gV = 5gV = 8
Model B
Figure 2.1: Upper panel: Branching Ratios for the two body decays of the neutral vector V 0 forthe benchmarks AgV =1 (left) and BgV =3 (right). Lower panel: Total widths corresponding to di↵erentvalues of the coupling gV in the models A (left) and B (right).
Therefore, for model BgV =3
the dominant BRs are into di-bosons and the fermionic decays are
extremely suppressed, of the order of one percent to one per mil. Moreover, the total width
increases with increasing gV since it is dominated by the di-boson width which grows with gVas expected from Eq. (2.33). Finally, in model B we see that a very large coupling gV (the case
of gV = 8 is shown in the Figure) leads to an extremely broad resonance, with �/M � 0.1,
for which the experimental searches for a narrow resonance are no longer motivated. For
this reason we expect, if no further suppression is present in the parameter cH , to be able to
constrain heavy vector models from direct searches only up to gV of the order 6�7. For larger
couplings di↵erent searches become important, like for instance those for four fermion contact
interactions (see for instance Refs. [83, 84]).
16
heavy vector triplet (HVT)
10.1007/JHEP09(2014)060
1 Feynman diagrams
W 0W
H
q0
q
b
b
l
⌫
(a)
XW
W
g
g
q
q̄
l
⌫
(b)
g
g
g
q
q̄
c, b
c̄, b̄
(c)
Figure 1.1: Heavy X particle production and decay.
1
Clemens Lange - Diboson resonances searches at CMS31.05.2016
Putting it all together
>currently, larger number of channels has been covered with 8 TeV data>differentiate between final states (number of leptons and jets)>violet analyses interpreted in dark matter scenarios
>several analyses repeated and improved w.r.t. 8 TeV (considering mX > 1TeV)>several more to come this year
31
W ➞ lν Z ➞ ll V ➞ qq Z ➞ νν H ➞ qqqq H ➞ ττ H ➞ bb H ➞ ɣɣ
W ➞ lν 13 TeV 13 TeVZ ➞ ll 13 TeV 13 TeV
V ➞ qq 13 TeV 13 TeV 13 TeV 13 TeV
Z ➞ νν 13 TeV 13 TeV
H ➞ qqqqH ➞ ττH ➞ bb 13 TeV 13 TeV 13 TeV
H ➞ ɣɣ
31.05.2016 Clemens Lange - Diboson resonances searches at CMS
8 vs. 13 TeV
>While 13 TeV has opened up new energy regime, integrated luminosity recorded in 2015 significantly below the one of 2012 ! 20 fb-1 vs. ~3 fb-1
>LHC is hadron collider - √s ≠ energy available in collision
>need to consider parton luminosities
>exceed 2012 reach with 2015 data already at 1-2 TeV resonance mass
>nevertheless, worthwhile combining results
32
100 10001
10
100
gg Σqq qg
WJS2013
ratios of LHC parton luminosities: 13 TeV / 8 TeV
lum
ino
sity
ra
tio
MX (GeV)
MSTW2008NLO
_
[website]
Clemens Lange - Diboson resonances searches at CMS31.05.2016
Combination of diboson analyses
>example here: V’ combination in HVT model B
>seven 8 TeV analyses, three at 13 TeV
>how to combine upper cross section limits from two different √s?
33
(TeV)V'M1 1.5 2 2.5
(pb)
WV/
VH→
V'
BR
× 95
%σ
-210
-110
1 (8 TeV)-119.7 fbCMS Preliminary
Obs.S
Asympt. CLσ 1± Exp.
SAsympt. CL
σ 2± Exp. S
Asympt. CL=3)
V (gB HVT
lllv qqqqllqq qqbb(4q)lvqq ττqqlvbb
(TeV)V'M1 2 3 4
(pb)
WV/
VH→
V'
BR
× 95
%σ
-210
-110
1
10 (13 TeV)-12.2-2.6 fbCMS Preliminary
Obs.S
Asympt. CLσ 1± Exp.
SAsympt. CL
σ 2± Exp. S
Asympt. CL=3)
V (gB HVT
lvqqllbb/lvbb/vvbbqqqq
CMS-PAS-B2G-16-007
Clemens Lange - Diboson resonances searches at CMS31.05.2016
Combination of diboson analyses
>convert cross section limits into signal strength limits
>8+13 TeV limits comparable at lower masses, 13 TeV dominates high mass
> lower masses: leptonic analyses, higher masses: hadronic final states
34
(TeV)V'M1 2 3 4
theo
ryσ/
95%
σ
-110
1
10
210
(8 TeV)-1 (13 TeV) + 19.7 fb-12.2-2.6 fbCMS Preliminary
Obs.S
Asympt. CLσ 1± Exp.
SAsympt. CL
σ 2± Exp. S
Asympt. CL=3)
V (gB HVT
lllv (8 TeV) qqbb(4q) (8 TeV)llqq (8 TeV) (8 TeV)ττqqlvqq (8 TeV) lvqq (13 TeV)lvbb (8 TeV) llbb/lvbb/vvbb (13 TeV)qqqq (8 TeV) qqqq (13 TeV)
(TeV)V'M1 2 3 4
theo
ryσ/
95%
σ
-110
1
10
210 (8 TeV)-1 (13 TeV) + 19.7 fb-12.2-2.6 fbCMS Preliminary
=3)V
(gB HVT
8 TeV
13 TeV
8+13 TeV
Obs.(solid)/ Exp.(dashed)S
Asympt. CL
CMS-PAS-B2G-16-007
31.05.2016 Clemens Lange - Diboson resonances searches at CMS
Combination of diboson analyses
>can translate observed limits into exclusion contours in the HVT couplings space
>additional input to theorists for model building
35
CMS-PAS-B2G-16-007
HcV
g-3 -2 -1 0 1 2 3
V/g Fc2 g
-1
-0.5
0
0.5
1
B
Mexpσ
≈ > 7% MthΓ
1.5 TeV2 TeV3 TeV
(8 TeV)-1 (13 TeV) + 19.7 fb-12.2-2.6 fb
CMSPreliminary
coupling to bosons
coup
ling
to fe
rmio
ns
Clemens Lange - Diboson resonances searches at CMS31.05.2016
Summary
>discovery of a diboson resonance might solve hierarchy problem
>however, currently no sign of new physics
>13 TeV results already exceed 8 TeV ones
>expect another boost with 2016 data
36
Clemens Lange - Diboson resonances searches at CMS31.05.2016
W-tagging calibration
>cutting on τ2/τ1-ratio ➜ need to know efficiency of cut in data and simulation
>select at generator level clean W-events and those that do not match
>perform simultaneous fit
38
pruned jet mass (GeV)40 50 60 70 80 90 100 110 120 130
Even
ts /
( 5 G
eV )
50
100
150
200
250
300
350tt single Top
VV W+jets
data HPν µ e/→W
CMSPreliminary
= 13TeV s at -1 2.2 fb
pruned jet mass (GeV)40 50 60 70 80 90 100 110 120 130
Even
ts /
( 5 G
eV )
20
40
60
80
100
120
140
160
180
200
220
240tt single Top
VV W+jets
data HPν µ e/→W
CMSPreliminary
= 13TeV s at -1 2.2 fb
Clemens Lange - Diboson resonances searches at CMS31.05.2016
boson-tagging efficiencies
39
Tagger BR(W/Z/H ➜ xx) efficiency mistag rate (q-/g-jets)
W/Z➜qq 70 % 35 % 1.2 %H➜bb 57 % 35 % 0.5 %H➜WW➜qqqq 10 % 35 % 1.5 %H➜ττ 6 % 35 % 0.03 %
Clemens Lange - Diboson resonances searches at CMS31.05.2016
Zɣ search limits
> recently published Z➜ll + ɣ search
40
CMS-PAS-EXO-16-019
5.4% width0.014% width
Resonance Mass [GeV]400 600 800 1000 1200 1400 1600 1800 2000
) [fb
]γZ
→ B
R(A
× σ
95%
CL
UL
on
0
50
100
150
200
250
300
W = 0.014%
Observed
σ 1±Expected
σ 2±Expected
(13 TeV)-1 2.7 fbCMS Preliminary
Resonance Mass [GeV]400 600 800 1000 1200 1400 1600 1800 2000
) [fb
]γZ
→ B
R(A
× σ
95%
CL
UL
on
0
100
200
300
400
500
600
W = 5.6%
Observed
σ 1±Expected
σ 2±Expected
(13 TeV)-1 2.7 fbCMS Preliminary
Recommended