QFTHEP2015 The 22 th International Workshop on High Energy Physics and Quantum Field Theory Samara Russian Federation Dr Bora Akgün Rice University on behalf of CMS Collaboration ID: 277925
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Slide1
Recent results of the CMS experiment
QFTHEP2015The 22th International Workshop on High Energy Physics and Quantum Field Theory, Samara (Russian Federation)Dr. Bora Akgün – Rice University(on behalf of CMS Collaboration)Slide2
Outline
Recent Results of the CMS Experiment - bora.akgun@cern.ch25 June 20152
CMS - Data CollectionSelected Results
Vector Bosons – arXiv:
1505.06520,
arXiv:
1503.05467
Quarkonia
–
PRL 114 (2015)
191802,
arXiv:
1501.07750
Rare Decays
–
Nature 522 (2015)
68
Top Physics –
arXiv:
1505.04480
SUSY –
arXiv:
1502.06031
Exotica
–
arXiv:
1502.04994
What to expect from Run2 and beyond
SummarySlide3
CMS Detector
Recent Results of the CMS Experiment - bora.akgun@cern.ch25 June 20153Slide4
Data Collection
Recent Results of the CMS Experiment - bora.akgun@cern.ch25 June 20154
Results presented in this talk have been produced with LHC Run-1 data collected by CMS experiment
CMS Public Results
twiki
https://
twiki.cern.ch
/
twiki
/bin/view/
CMSPublic
/
PhysicsResultsSlide5
CMS Standard Model Summary Plot
Recent Results of the CMS Experiment - bora.akgun@cern.ch25 June 20155
Great agreement btw theory and measurements Slide6
Vector Bosons
Recent Results of the CMS Experiment - bora.akgun@cern.ch25 June 20156
W and Z can be measured very accurately through their leptonic decays, photon energies precisely measured in the electromagnetic calorimeter Z and photons used for calibration of jets, Z used as a candle to determine lepton efficiencies
Vector boson plus jets are major backgrounds in beyond standard model searches and excellent testing ground for QCD NLO predictions
Diboson
processes (ZZ and
γγ
) are major SM backgrounds for Higgs measurements
WZ and ZZ w/
Z
νν
major contribution to backgrounds in searches w/ large missing transverse energy (e.g. SUSY) Slide7
Z+jets
/ Photon+jetsRecent Results of the CMS Experiment - bora.akgun@cern.ch25 June 20157
Z+jets
Photon+
jets
V+jets
are major backgrounds in beyond standard model searches and excellent testing ground for QCD NLO predictions
arXiv:1505.06520
n
jet
≥1Slide8
Z+jets
/ Photon+jetsRecent Results of the CMS Experiment - bora.akgun@cern.ch25 June 20158
The ratio of Z + jets to γ
+ jets
Both simulations reproduce the shape of the ratio better than the individual distributions in all selections
arXiv:1505.06520
n
jet
≥1
n
jet
≥2Slide9
Production cross-section for
ZZllννRecent Results of the CMS Experiment - bora.akgun@cern.ch25 June 2015
9
ZZ
llνν
production cross section measured
Using a profile
likelihood
fit to the reduced-
E
T
miss
Main backgrounds
DY,
WZ,
WW
,W+jets,
top
σ
(
pp
ZZ
) = 5.2
+1.5
-1.4
(stat)
+1.4
-1.1
(
syst
)±0.2(
lumi
)
pb
at 7
TeV
σ
(
pp
ZZ
) = 6.9
+0.8
-0.8
(stat)
+1.8
-1.4
(
syst
)±0.3(
lumi
)
pb
at 8
TeV
Theory
calculations w/ NLO QCD
and
NLO EW
σ
(
pp
ZZ
) = 6.2
+0.3
-0.2
at 7
TeV
σ
(
ppZZ) = 7.6+0.3-0.3 at 8 TeV
arXiv:1503.05467Slide10
Production cross-section for
ZZllννRecent Results of the CMS Experiment - bora.akgun@cern.ch25 June 2015
10
ZZγ
and ZZZ expected to be null at the tree level
Enhancement in ZZ production rate compared to SM indicate the existence of anomalous boson couplings
arXiv:1503.05467
No observation of new physics
stringent limits on the relevant Anomalous Triple Gauge Coupling (ATGC) parameters Slide11
Charmonium
spectrumRecent Results of the CMS Experiment - bora.akgun@cern.ch25 June 201511
c
ross sections and polarizations
c
ross section ratio
observation, cross section
observation with > 5σSlide12
Prompt
ψ(ns) cross-sectionsRecent Results of the CMS Experiment - bora.akgun@cern.ch25 June 201512
Yields are corrected for efficiency and acceptance on an event-by-event basis
PRL 114 (2015) 191802Slide13
Prompt
ψ(ns) cross-sectionsRecent Results of the CMS Experiment - bora.akgun@cern.ch25 June 201513
Yields are corrected for efficiency and acceptance on an event-by-event basis
Four polarization scenarios are considered
P
T
reach is extended compared to previous measurements
FKLSW band is obtained in a fit to previous data w/ essentially P
T
<
30
GeV
and extrapolated to higher
P
T
values
PRL 114 (2015) 191802
u
n-polarized scenario
u
n-polarized scenarioSlide14
Bottomonium
spectrumRecent Results of the CMS Experiment - bora.akgun@cern.ch25 June 201514
c
ross sections and polarizations
c
ross section ratioSlide15
ϒ
(ns) differential cross-sectionsRecent Results of the CMS Experiment - bora.akgun@cern.ch25 June 201515
Acceptance calculated w/ polarization values measured by CMS (PRL 110 (2013) 081802)P
T
reach is extended compared to previous measurements
arXiv:1501.07750
ϒ
(
2S)
,
ϒ
(
3S)
scaled by 0.1, 0.01, respectively
NRQCDSlide16
ϒ
(ns) production ratios Recent Results of the CMS Experiment - bora.akgun@cern.ch25 June 201516
arXiv:1501.07750
Exponential fit – 10 <
P
T
< 20
GeV
Power-law fit – P
T
>20
GeV
Change in ratios occur at the same P
T
range in which
dσ
/
dP
T
also changes behavior
Slide17
B
S0μ+μ- and B0
μ+μ-
Recent Results of the CMS Experiment - bora.akgun@cern.ch
25 June 2015
17
SM predicts small branching fractions for B
S
0
μ
+
μ
-
and B
0
μ
+
μ
-
Direct flavor-changing neutral currents not possible in SM, theories beyond SM predict larger branching fractions
Nature 522 (2015) 68Slide18
First observation - B
S0μ+μ- (CMS & LHCb)
Recent Results of the CMS Experiment - bora.akgun@cern.ch
25 June 2015
18
Weighted distribution of
dimoun
mass-spectrum, superimposed in a combined fit
First
observation
of B
S
0
μ
+
μ
-
(6.2σ) and
evidence
for B
0
μ
+
μ
-
(3.2
σ
)
Nature 522 (2015) 68Slide19
Combined result - B
S0μ+μ- (CMS & LHCb)
Recent Results of the CMS Experiment - bora.akgun@cern.ch
25 June 2015
19
Likelihood in
B
S
0
μ
+
μ
-
vs
B
0
μ
+
μ
-
branching ratio plane
BR: B
S
0
μ
+
μ
-
=
2.8
+0.7
-0.6
* 10
-9
(0.76
+0.20
-0.18
* SM)
BR: B
0
μ
+
μ
-
= 3.9
+1.6
-1.4
* 10
-10
(
3
.7
+
1
.6
-1.4
* SM)
Nature 522 (2015) 68Slide20
Top mass measurements
Recent Results of the CMS Experiment - bora.akgun@cern.ch25 June 201520
The most massive particle known to date
Very short lifetime shorter than
hadronization
timescale
The only elementary high mass particle that has color
EWK, QCD and flavor physics
Combined top mass using all CMS Run-1 data
172.38±0.10(stat.)
±0.65(syst.)
GeV
Slide21
t
tbar production cross-section at 7/8TeVRecent Results of the CMS Experiment - bora.akgun@cern.ch25 June 201521
ttbar production cross-section measured w/ different channels at 7 and 8
TeV
t
tbar
is a major background for many processes Slide22
t
tbar differential measurementsRecent Results of the CMS Experiment - bora.akgun@cern.ch25 June 201522
MC generators predict harder dilepton mass and lepton P
T
spectrum
than observed in data
Powheg+Herwig6 provide a satisfactory agreement
8
TeV
results are
input
for future MC
tuning
arXiv:1505.04480Slide23
SUSY searches
Recent Results of the CMS Experiment - bora.akgun@cern.ch25 June 201523
SUSY, popular BSM theoriesSolves the hierarchy problemProvides a suitable dark matter candidate
SUSY corrections allow for high energy unification of strong and electroweak couplings
Searches involve typically the presence of large missing transverse energy and
multijetsSlide24
SUSY search w/ two leptons, jets and
ETmiss Recent Results of the CMS Experiment - bora.akgun@cern.ch25 June 2015
24
arXiv:1502.06031
The invariant mass distribution of the two-lepton system can exhibit an excess that increases with the di-lepton mass, followed by a sharp decrease, if the two leptons originate from the decay of a neutral particle decayed from a bottom
squark-antisquark
production
Mass difference btw Χ
2
0
and Χ
1
0
fixed to 70
GeV
Mass of the
slepton
chosen to lie halfway btw the masses of
Χ
2
0
and Χ
1
0
Lepton pair from the decay of an o-shell Z boson from
gluino
pair production
1
2
3
3.Slide25
SUSY search w/ two leptons, jets and
ETmiss Recent Results of the CMS Experiment - bora.akgun@cern.ch25 June 2015
25
M
ll
> 20
GeV
Njets
≥ 2
arXiv:1502.06031
Low mass significance: 2.6σ
No evidence for a statistically significant signalSlide26
SUSY search w/ two leptons, jets and
ETmiss: setting limitsRecent Results of the CMS Experiment - bora.akgun@cern.ch25 June 2015
26
arXiv:1502.06031Slide27
Exotica: Narrow high-mass resonance decaying to Z and H
Recent Results of the CMS Experiment - bora.akgun@cern.ch25 June 201527
arXiv:1502.04994
A search for a highly massive ( ≥ 0.8TeV) and narrow resonance decaying to Z and H bosons that decay in turn to merged
dijet
and
ττ
final states
τ
decaying
leptonically
and
hadronically
Advanced reconstruction techniques in boosted topology
Main backgrounds (simulated in MC)
Z+jets
/
W+jets
Ttbar
, single-t
ZZ,WW,QCD
Main source of uncertainty: limited MC statistics for signal efficiencies and background estimation Slide28
Exotica: Narrow high-mass resonance decaying to Z and H
Recent Results of the CMS Experiment - bora.akgun@cern.ch25 June 201528
arXiv:1502.04994
From a combination of all possible decay modes of the
τ
leptons, production cross sections in [0.9-27.8fb] depending on the resonance mass [0.8-2.5TeV], are excluded at a 95% CL Slide29
What have we been doing lately?
Recent Results of the CMS Experiment - bora.akgun@cern.ch25 June 201529
Finishing analyses w/ 2012 data Many results and publications (≥400), more to come..Long Shutdown (LS) – 1: 2013-2015
Fixes and upgrades to CMS detector
Pixel detector taken out, misbehaving channels (~5%) fixed and installed back to CMS
w/ an additional part - pilot system w/ upgrade electronics and readout
Muon
detectors
New stations (CSC/RPC) to complete redundancy, new electronics for triggering
Narrower
beampipe
Preparation for upgrade pixel detector in 2017
Re-commissioning of the detector for Run-2 Slide30
Detector
Improvements for Run 2Recent Results of the CMS Experiment - bora.akgun@cern.ch25 June 201530
Muons
Completion of forward detector
4
th
layer in ME
RPCs to |
η
|=4
Tracker
at -20
0
C
Pixel Pilot System
New Beam pipeSlide31
13
TeV CollisonsRecent Results of the CMS Experiment - bora.akgun@cern.ch25 June 201531
June 3
rd
: First collisions at the new center of mass energySlide32
LHC plan for 2015
Recent Results of the CMS Experiment - bora.akgun@cern.ch25 June 201532Slide33
What to expect in Run-2?
Recent Results of the CMS Experiment - bora.akgun@cern.ch25 June 201533
EW & QuarkoniaImprove on precision w/ higher statistics
Top
Increase mass precisions w/ better jet energy scale systematic uncertainties
Use boosted reconstruction techniques to perform differential cross-section measurements
Improve precision on
ttZ
,
ttW
,
ttH
cross-sections
Higgs
Look for deviations from SM w/ higher precision
SUSY
Discovery?
??Slide34
Summary
Recent Results of the CMS Experiment - bora.akgun@cern.ch25 June 201534Only a
small portion of results out of the rich long list of measurements performed by CMSIn general predictions provide a good description of data
CMS is ready for Run-2 data taking (already started)
Sophisticated reconstruction techniques,
analysis tools
, analysis methodologies
and
interpretation
approaches
have been developed and matured
during the
previous years
Exciting times ahead of us