Adam Falkowski. 750 GeV discussion. LAL Orsay, 18 January 2016

Transcription

1 Adam Falkowski 75 GeV discussion LAL Orsay, 18 January 216

2 Is it true? Davis,Fairbairn,Heal,Tunney arxiv: Text Claim that another function fits background better than ATLAS fit, and when it s used, significance drops to 2 sigma. But I can t reproduce their numbers (I get 3.2 sigma ATLAS -> 2.6 Davis et al.) No theory motivation for another background component kicking in at ~5 GeV Proposed background overshoots the tail by more than 3 sigma

3 What is the mass and cross section? 14 LHC 13 TeV, G=5 GeV 1 LHC 8+13 TeV, G=5 GeV 12 8 shppæslâbrhsæggl@fbd shppæslâbrhsæggl@fbd m m For Run-2 data the best fit is 75 GeV particle with σ(pp S) Br(S γγ) 5 fb Assuming particles produced in gluon fusion, dirty combination with 8 TeV data reduces best fit cross section to σ(pp S) Br(S γγ) 2.5 fb However, combined significance remains around 3 sigma (Δχ^2 11 between best fit and no signal hypothesis)

4 What is the width? 2 LHC 8+13 TeV, m S =75 GeV 15 shppæslâbrhsæggl@fbd G In combined data, small but not statistically significant preference for a large width Large width more difficult theoretically and requires larger diphoton cross section

5 Can it be invisible? where e is the electromagnetic constant, gs isgev the QCD coupling consta Singlet+T'+Dcsgg =.25+Exotic; ms =75 1 for dimensional reasons. In our numerical analyses we u is introduced evaluated at 75 GeV, gs = 1.7, and e =.31. These couplings are but they may 8 arise effectively in a renormalizable model after integr quarks at one loop. We assume the singlet has a Yukawa coupling yx t X which resides in the fundamental representation of SU (3)c and has m 6 charge QX, Singlet+T'+Exotic; ms =75 GeV 15 pb pb 4.5 pb 5 pb 2 run-1 monojets 6 run-1 monojets 8 3 pb 1 LS,e e2 gs2 = cs SAµ Aµ + csgg SGaµ Gaµ, 4v 4v 4 2 pb 2 pb csgg pb L yx S X X..1 pb 6 5 pb..1 pb csgg Large (1 GeV or more) width difficult to explain by invisible decays due to run-1 monojet bounds Loophole if huge contribution to effective coupling to photons present Nevertheless, invisible or other exotic (e.g. lepton jets) signals at 75 GeV interesting to search for

6 Related diboson signals? 6 LHC 8+13 TeV, G=5 GeV 5 ZZ shppæslâbrhsæggl@fbd WW Zg m Assuming only S Wμν Wμν is present (from integrating out loop of particles with SU(2) and no U(1) quantum numbers), other diboson searches at 8 TeV are in some tension with best fit region to diphoton data No tension yet if only S Bμν Bμν is present, but Zγ still observable in future

7 Model independent dijet signal? CL (darker green) and 95% CL (lighter green) regions in the plane of mass alar resonance decaying to 2 photons favored by the ATLAS and CMS run-1 Singlet+X; ms =75 GeV; small width results are presented assuming a Breit-Wigner = 5 GeV (left).4 shape1 with pb 2 2 pb 3 ). 1 3 CMS-PAS-EXO-14-5 run-1 dijet search with scouting data csgg show the best fit region for ms = 75 GeV.3 in the plane of the resonance n. Again, we see slight preference for a large width: the best fit point and = 4.8 fb. Finally, in the full 3D scan we find the best fit point 6 fb, and S 4 GeV. This is preferred over the best fit point A Singlet.1.1 pb g a minimal model which addresses the excess discussed above. We 1 pb ar, S, coupled to photons and gluons.. LS,e e2 gs2 = cs SAµ Aµ + csgg SGaµ Gaµ, 4v 4v csgg (3.1) magnetic constant, gs is the QCD coupling constant, and v ' 246 GeV ensional reasons. In our numerical analyses we use the SM couplings V, gs = 1.7, and e =.31. These couplings are non-renormalizable, effectively in a renormalizable model after integrating out vector-like We assume the singlet has a Yukawa coupling yx to a vector-like quark e fundamental representation of SU (3)c and has mass mx and electric Dijet resonance can be observable in portion of parameter space, but it can also be buried forever under SM background L yx S X X. (3.2)

8 How much mixing with Higgs?.2 Doublet+Singlet+X; y X =2.5, m X =1 TeV, m S =75 GeV.1 ZZ Large mixing angles excluded by WW and ZZ resonances searches, and by Higgs couplings measurements For T particle generating effective couplings of 75 GeV particle to gluons and photons, mixing angle needs to be smaller than.1 More generally, mixing angle constrained to be smaller than.1 sinhal Q X Higgs couplings

9 Can it solve hierarchy problem? Doublet+Singlet+T'; sinhal=.8, m S =75 GeV; small width 1 5 yx m X For T particle generating effective couplings of 75 GeV particle to gluons and photons, the same particle may possibly cancel quadratic divergences of from to loop contributions to Higgs mass