8/6/2019 HCOL meeting about CDF Wjj anomaly: by Grisha Kirilin

1/19

8/6/2019 HCOL meeting about CDF Wjj anomaly: by Grisha Kirilin

2/19

0911.4449: CDF original analysis of mjj in WV production (3.9 fb-1). Small bump

observed in the region 150-180 GeV.

0907.4398: D search based on 1.1 fb-1 no excess in this mass range

1104.0699 (2 May): CDF new analysis with hard cuts. The bump confirmed at 3.2.

April-May: huge bunch of NSM explanations (>50) and two similar SM ones:

T. Plehn and M.Takeuchi (1104.4087, 20 Apr)

Z.Sullivan and A.Menon (1104.3790, 1 May)

Giovanni Punzi, 23th Rencontres de Blois, May 30. CDF new analysis based on 7.3 fb-1

luminosity. After including all systematic uncertainties 4.1 difference with SM probably

the most significant for SM ever

CDF online note (A. Annovi, P. Catastini, V. Cavaliere, L. Ristori). CDF replies doubts andgives more details about excess.

ATLAS note based on 33 pb-1 (no excess but luminosity is too small)

1106.1921 (9 Jun): new D analysis no bump

History and references (arXiv only)

http://arxiv.org/abs/arXiv:0911.4449http://arxiv.org/abs/arXiv:0907.4398http://arxiv.org/abs/arXiv:1104.0699http://www-cdf.fnal.gov/physics/ewk/2011/wjj/7_3.htmlhttp://arxiv.org/abs/arXiv:1106.1921http://arxiv.org/abs/arXiv:1106.1921http://www-cdf.fnal.gov/physics/ewk/2011/wjj/7_3.htmlhttp://arxiv.org/abs/arXiv:1104.0699http://arxiv.org/abs/arXiv:0907.4398http://arxiv.org/abs/arXiv:0911.4449

8/6/2019 HCOL meeting about CDF Wjj anomaly: by Grisha Kirilin

3/19

Review of CDF analysis: 1104.0699

Signature: high pT isolated lepton + exactly two jets + missing energy

* pT,l>20GeV* ET,j>30GeV

* PT,jj>40GeV

* ET>25GeV* j

8/6/2019 HCOL meeting about CDF Wjj anomaly: by Grisha Kirilin

4/19

8/6/2019 HCOL meeting about CDF Wjj anomaly: by Grisha Kirilin

5/19

Lepto-phobic Z' (e.g. 1103.6035)

>

>

>

>

W

l

u/d

q-

d/u--

q

Z'u/d

t~

>

>

l

q-

q-

q

t~

q

>

>

>

> b~/

b~/

New mother resonance

(techno-particles, super-partners, etc)

>

>

>

>

l

q-

q

W~

W~

Possible NSM processes

Different pole structures:

http://arxiv.org/abs/1103.6035http://arxiv.org/abs/1104.0976http://arxiv.org/abs/1104.1002http://arxiv.org/abs/1104.1002http://arxiv.org/abs/1104.0976http://arxiv.org/abs/1103.6035

8/6/2019 HCOL meeting about CDF Wjj anomaly: by Grisha Kirilin

6/19

Possible doubts on the CDF analysis

The analysis requires a perfect control of the all SM contribution, but:

even the peak in mjj due to WV seemed to be not very well simulated

What would be result of using other MC tools instead of ALPGEN+PYTHIA?

Jet energies are corrected for detector effects. The systematic uncertainty due touncertainties in the jet energy scale (3%) affects all components with the exception

of multijet QCD, which is derived from data. The largest systematic uncertainties

arise from the modeling of the W+jets and multijet QCD shapes. What if we vary

the jet energy scale by a few percent? Does it shift W+jets contribution forward?

Additional peak appears exactly on the place of the second peak from top quark

production what would result if we change the relative normalization of WV and

top production? Does it reproduce the excess?

8/6/2019 HCOL meeting about CDF Wjj anomaly: by Grisha Kirilin

7/19

Possible doubts on the CDF analysis

In order to estimate NLO effects, the original analysis includes the comparison of

W+2 partons predictions made by LO ALPGEN+PYTHIA and MCFM. What abouttop production? Do NLO corrections yield more peaked top contribution?

There is Njet=2 requirement. What is theoretical and experimental status of jet

survival probability? It is important for estimating top background passing through

this jet veto.

May be it is just statistical fluctuation?

8/6/2019 HCOL meeting about CDF Wjj anomaly: by Grisha Kirilin

8/19

There is no shift because the increasing of JES leads to additional events passing the

analysis cuts. The significance is always above 3.

8/6/2019 HCOL meeting about CDF Wjj anomaly: by Grisha Kirilin

9/19

Review of 1104.4087 (T. Plehn and M.Takeuchi)

>

>

>Wb

q-

q

t

boost

>

>

W

q-

q

0.43 top and a compensating shift in the WV

rate of the order of O(10%).

Of course, this does not mean a 43% shift in the theoretically predicted total cross section fortop production. Almost a third of the the combined top sample is single top production. For

the jet veto survival probability the CDF analysis includes neither a reliable experimental nor a

reliable theoretical estimate. Thus, we expect a very large error bar on the single top rate

after cuts and effciencies.

8/6/2019 HCOL meeting about CDF Wjj anomaly: by Grisha Kirilin

12/19

CDF objections about top (online note)

We perform a comparison between the b-tagging rate in the 120 < MJJ< 160 GeVregion and

the 100 < MJJ < 120 GeVor160 < MJJ < 180 GeV"sideband" regions. We determine the

ratio NTAG / NUNTAG for several b-tag types where NUNTAG is the number of events without any

b-tag information and NTAG can be sub-classed as:

0 T : neither of the two jets has a positive SECVTX Tight tag. 1 T : at least one of the two jets has a positive SECVTX Tight tag. 2 T : both jets have a positive SECVTX Tight tag.

0 L : neither of the two jets has a positive SECVTX Loose tag.

1 L : at least one of the two jets has a positive SECVTX Loose tag.

2 L : both jets have a positive SECVTX Loose tag.

b-tagging in the excess region

http://www-cdf.fnal.gov/physics/ewk/2011/wjj/7_3.htmlhttp://www-cdf.fnal.gov/physics/ewk/2011/wjj/7_3.html

8/6/2019 HCOL meeting about CDF Wjj anomaly: by Grisha Kirilin

13/19

CDF objections about top (online note)

b-tag rate in the muon (left) and electron (right) samples

No significant enhancement of b-tagged events is observed in the "excess" region compared to

the sideband regions. This highlights that the excess is not arising solely from b-bbar events

and that the excess is not due to an under-estimated t-tbar content since in these events at

least one of the jets should give rise to a b-quark in the "excess" region.

http://www-cdf.fnal.gov/physics/ewk/2011/wjj/7_3.htmlhttp://www-cdf.fnal.gov/physics/ewk/2011/wjj/7_3.html

8/6/2019 HCOL meeting about CDF Wjj anomaly: by Grisha Kirilin

14/19

CDF objections about top (Giovanni Punzi talk)

To summarize: this cannot possibly be top background

There is no significant tagged component

Top-enriched control samples show perfect agreementwith simulation

When using actual detector simulation, the top

background does not peak at the right place

8/6/2019 HCOL meeting about CDF Wjj anomaly: by Grisha Kirilin

15/19

To model the W+jets shape two different set of programs are used: ALPGEN (v2.1) interfaced to PYTHIA (v6.326) with the MLM matching scheme

SHERPA (v1.2.2) with a Q cut of 15 GeV (to match ALPGEN) using CKKW

matching.

The (statistical-only) significance of the excess when the W+jets shape is modeledby SHERPA is 3.8 standard deviations compared to 4.8 with ALPGEN.

Detailed comparisons of kinematics distributions between the two generators can

be found here

http://www-cdf.fnal.gov/physics/ewk/2011/wjj/sherpa_alpgen_comparison.html

CDF objections about MC generators (online note)

http://www-cdf.fnal.gov/physics/ewk/2011/wjj/sherpa_alpgen_comparison.htmlhttp://www-cdf.fnal.gov/physics/ewk/2011/wjj/sherpa_alpgen_comparison.htmlhttp://www-cdf.fnal.gov/physics/ewk/2011/wjj/sherpa_alpgen_comparison.htmlhttp://www-cdf.fnal.gov/physics/ewk/2011/wjj/sherpa_alpgen_comparison.html

8/6/2019 HCOL meeting about CDF Wjj anomaly: by Grisha Kirilin

16/19

CDF objections about MC generators (online note)

MJJ compared to the

data with the W+jets

shape modeled by

SHERPA.

Background subtracted

MJJ fit with the W+jets

shape modeled by

SHERPA MJJ compared to the

data with the W+jets

shape modeled by

ALPGEN

A comparison(normalized to unit area)

of the SHERPA and

ALPGEN W+jets MJJ

distribution.

http://www-cdf.fnal.gov/physics/ewk/2011/wjj/sherpa_alpgen_comparison.htmlhttp://www-cdf.fnal.gov/physics/ewk/2011/wjj/sherpa_alpgen_comparison.html

8/6/2019 HCOL meeting about CDF Wjj anomaly: by Grisha Kirilin

17/19

The analysis requires Njet=2. The requirement is relax to Njet2 which is expected to be

modeled better. The significance of the excess considering only statistical uncertainties remains

essentially unchanged at4.8

CDF objections about jet veto (online note)

http://www-cdf.fnal.gov/physics/ewk/2011/wjj/7_3.htmlhttp://www-cdf.fnal.gov/physics/ewk/2011/wjj/7_3.html

8/6/2019 HCOL meeting about CDF Wjj anomaly: by Grisha Kirilin

18/19

Kinematic Distributions (online note)

Mass of JJ + l system.

Is it mother resonance?

Does the excess contain a real W?

Look at Wl transverse mass.

http://www-cdf.fnal.gov/physics/ewk/2011/wjj/kinematics.htmlhttp://www-cdf.fnal.gov/physics/ewk/2011/wjj/kinematics.html

8/6/2019 HCOL meeting about CDF Wjj anomaly: by Grisha Kirilin

19/19

Concluding remarks about LHC

After making new D analysis public the score in Fermilab is 2:2. What about LHC? See

ATLAS note (ATLAS-CONF-2011-069)

Nothing, however if there is a 300 GeV mother resonance in gg channel then the LHC should

be able to see it already with 200 pb-1 luminosity. See LHC progress here (1fb-1 already!).

http://cdsweb.cern.ch/record/1349310/files/ATLAS-CONF-2011-069.pdfhttps://lhc-statistics.web.cern.ch/LHC-Statistics/https://lhc-statistics.web.cern.ch/LHC-Statistics/http://cdsweb.cern.ch/record/1349310/files/ATLAS-CONF-2011-069.pdf