CDF Collab. at Fermilab: WW/WZ Prod. Lepton+Jet Decays

[tom.stoer]

Has anybody checked the latest arxiv papers regarding technipions, SUSY-based explanation, Z' and string theory?

 

[tom.stoer]

I found these papers - but haven't checked them yet.

http://arxiv.org/abs/1104.0976
Technicolor at the Tevatron
Authors: Estia J. Eichten, Kenneth Lane, Adam Martin
(Submitted on 6 Apr 2011)
Abstract: We propose that the 3.2 sigma excess at ~150 GeV in the dijet mass spectrum of W + jets reported by CDF is the technipion $\pi_T$ of low-scale technicolor. Its relatively large cross section is due to production of a narrow $Wjj$ resonance, the technirho, which decays to W + $\pi_T$. We discuss ways to enhance and strengthen the technicolor hypothesis and suggest companion searches at the Tevatron and LHC.

http://arxiv.org/abs/1104.1002
Signatures of Resonant Super-Partner Production with Charged-Current Decays
Authors: Can Kilic, Scott Thomas
(Submitted on 6 Apr 2011)
Abstract: We investigate hadron collider signatures arising from a topology characterized by the production of a primary resonance that undergoes a charged-current transition to a secondary resonance by emitting a W-boson. The secondary resonance subsequently decays to two jets. This topology can arise in supersymmetric theories with R-parity violation where the lightest supersymmetric particles are either a pair of squarks, or a pair of sleptons and a sneutrino. The resulting signal can have a cross section consistent with the recent Wjj observation reported by the CDF collaboration, while remaining consistent with other constraints. The supersymmetric signal with squarks has a significant charge asymmetry in the same channel at the LHC. With strongly interacting resonances such as squarks, pair production topologies additionally give rise to 4 jet and W$^+$W$^-$+ 4 jet signatures, each with two equal-mass dijet resonances within the 4 jets.

http://arxiv.org/abs/1103.6035
Light Z' Bosons at the Tevatron
Authors: Matthew R. Buckley, Dan Hooper, Joachim Kopp, Ethan Neil
(Submitted on 30 Mar 2011 (v1), last revised 1 Apr 2011 (this version, v2))
Abstract: New gauge bosons with Standard Model-like couplings to leptons are constrained by collider searches to be heavier than approximately ~1 TeV. A Z' boson with suppressed couplings to leptons, however, could be much lighter and possesses substantial couplings to Standard Model quarks. In this article, we consider a new leptophobic Z' gauge boson as a simple and well motivated extension of the Standard Model, and discuss several of its possible signatures at the Tevatron. We find that three of the recent anomalies reported from the Tevatron - in particular the top-quark forward-backward asymmetry and excesses in the 3b and W + 2 jets final states - could be explained by a new Z' with a mass of approximately 150 GeV, relatively large couplings to quarks, and suppressed couplings to electrons and muons. Moreover, we find that such a particle could also mediate the interactions of dark matter, leading to potentially interesting implications for direct detection experiments.

http://arxiv.org/abs/1104.0243
A Z' Model for the CDF Dijet Anomaly
Authors: Felix Yu
(Submitted on 1 Apr 2011 (v1), last revised 12 Apr 2011 (this version, v2))
Abstract: We adopt a bottom-up approach to constructing a new physics model to explain the CDF excess seen in dijets with an associated lepton and missing transverse energy. We find that the 145 GeV broad feature seen by CDF in the dijet invariant mass distribution can be explained by a Z' boson with a mass of 145 GeV that couples only to first generation quarks. After dijet resonance constraints are considered, a sizeable region of the parameter space favored by the CDF anomaly remains viable.

http://arxiv.org/abs/1104.1375
Tevatron Wjj Anomaly and the baryonic $Z'$ solution
Authors: Kingman Cheung, Jeonghyeon Song
(Submitted on 7 Apr 2011 (v1), last revised 12 Apr 2011 (this version, v2))
Abstract: The latest CDF anomaly, the excess of dijet events in the invariant-mass window 120-160 GeV in associated production with a $W$ boson, can be explained by a baryonic $Z'$ model in which the $Z'$ boson has negligible couplings to leptons. Although this $Z'$ model is hardly subject to the Drell-Yan constraint from Tevatron, it is constrained by the dijet data from UA2 ($\sqrt{s} = 630$ GeV), and the precision measurements at LEP through the mixing with the SM $Z$ boson. We show that under these constraints this model can still explain the excess in the $M_{jj} \sim 120 - 160$ GeV window, as well as the claimed cross section $\sigma(W Z') \sim 4$ pb. Implications at the Tevatron would be the associated production of $\gamma Z',\; Z Z'$, and $Z'Z'$ with the $Z' \to jj$. We show that the $\gamma Z' \to \gamma jj$ channel could be promising to probe this model at the Tevatron.

http://arxiv.org/abs/1104.2302v1
Stringy origin of Tevatron Wjj anomaly
Authors: Luis A. Anchordoqui, Haim Goldberg, Xing Huang, Dieter Lust, Tomasz R. Taylor
(Submitted on 12 Apr 2011)
Abstract: The invariant mass distribution of dijets produced in association with W bosons, recently observed by the CDF Collaboration at Tevatron, reveals an excess in the dijet mass range 120-160 GeV/c^2, 3\sigma beyond Standard Model expectations. We show that such an excess is a generic feature of low mass string theory, due to the production and decay of a leptophobic Z', a singlet partner of SU(3) gluons coupled primarily to the U(1) baryon number. In this framework, U(1) and SU(3) appear as subgroups of U(3) associated with open strings ending on a stack of 3 D-branes. In addition, a minimal model contains two other stacks to accommodate the electro-weak SU(2) \in U(2) and the hypercharge U(1). Of the three U(1) gauge bosons, the two heavy Z' and Z'' receive masses through the Green-Schwarz mechanism. This model contains a free parameter which controls the Z-Z' mixing and can be chosen to simultaneously ensure three phenomenologically desirable features: small Z-Z' mixing permitting low Z' mass in the 120-160 GeV/c^2 range; very small (less than 1\%) branching ratio into electrons; and a large hierarchy between Z'' and Z' masses.

 

[daschaich]

Has anybody checked the latest arxiv papers regarding technipions, SUSY-based explanation, Z' and string theory?

Technipions yes, Z' somewhat, the others no. (I'm rather far behind on the arXiv in general, but I work with some of these authors.)

I'm mainly waiting for the DZero paper, which people at Fermilab tell me is expected before the end of the month. They also tell me that nobody from DZero is dropping any hints about what (if anything) they see.

PS. I wrote the above before seeing your list. You might want to add http://arxiv.org/abs/1012.5814 to it. I haven't looked at it closely, but the abstract makes it sound like it was written with some anticipation of this result.

 

[daschaich]

PS. I wrote the above before seeing your list. You might want to add http://arxiv.org/abs/1012.5814 to it. I haven't looked at it closely, but the abstract makes it sound like it was written with some anticipation of this result.

Or just skip to http://arxiv.org/abs/1104.2893 that appeared a few hours ago.

This abstract describes a different process for obtaining W+dijet, but the basic model looks pretty similar.

 

[petergreat]

This paper claims a connection between the CDF result and dark matter detections at CoGeNT and DAMA/LIBRA:
http://arxiv.org/abs/1104.3145

 

[johnbaldry]

The latest on a possible new particle

Hi

Regarding the recent sigma3 verification of a possible new particle, can anyone tell me why this particle is different to the many other know particles, in that it would have a force associated it with it, that we do not yet know about.

Most other known particles do not have a force associated with them

Thanks
Arthur S.

 

[Haelfix]

CDF has just released an update on the 150 GEV anomaly, and have found that it has increased in significance to 4.8 sigma, which is nearly a discovery:

http://blois.in2p3.fr/2011/transparencies/punzi.pdf

Incredibly, it has been now determined that this cannot be due to top quark background estimation errors (at least not simple ones). And of course, as has been known for some time, it turned out that the jet energy scaling argument floating around the internet was unlikely (the anomaly persists at ~3 sigma even if you ramp it up 7%).

Anyway, this is quite a bombshell! It will need to be confirmed by D0 or the LHC, but something is either very wrong with CDF, there is a very serious error in our theoretical understanding of the standard model, or there is new physics!

 

[Lapidus]

CDF has just released an update on the 150 GEV anomaly, and have found that it has increased in significance to 4.8 sigma, which is nearly a discovery:

http://blois.in2p3.fr/2011/transparencies/punzi.pdf

Incredibly, it has been now determined that this cannot be due to top quark background estimation errors (at least not simple ones). And of course, as has been known for some time, it turned out that the jet energy scaling argument floating around the internet was unlikely (the anomaly persists at ~3 sigma even if you ramp it up 7%).

Anyway, this is quite a bombshell! It will need to be confirmed by D0 or the LHC, but something is either very wrong with CDF, there is a very serious error in our theoretical understanding of the standard model, or there is new physics!

Exciting! Any new weblinks where these new findings are discussed or being commented on?

 

[daschaich]

CDF has posted many updated plots and comments here:
http://www-cdf.fnal.gov/physics/ewk/2011/wjj/7_3.html
They claim 4.1sigma significance considering both statistical and systematic uncertainties (the 4.8sigma only considers statistical uncertainties).

There are rumors of a DZero release on this sometime next week, although they've been very good so far about concealing exactly what they're going to say.

 

[daschaich]

There are rumors of a DZero release on this sometime next week, although they've been very good so far about concealing exactly what they're going to say.

Here it is:
http://www-d0.fnal.gov/Run2Physics/WWW/results/final/HIGGS/H11B/

They say: "We find no evidence for anomalous resonant dijet production".

 

[zaybu]

At the same time, doesn't it also rule out the Higgs Boson?

 

[daschaich]

At the same time, doesn't it also rule out the Higgs Boson?

Nope, standard model Higgs cross sections are much smaller.