Graduate Students Seminar Paul-Scherrer-Institut. Search for Excited Quarks

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1 Graduat Studnts Sminar Paul-Schrrr-Institut Sarch for Excitd Quarks Jan Bckr Univrsity of Zurich

2 Sarch for Excitd Quarks Framwork Excitd frmions and comositnss Phnomnological framwork Production of xcitd frmions Production and dcay of xcitd frmions at HERA q analysis Ovrviw of th q analysis H1 dtctor and th q dcay signatur Standard modl background rocsss Prsnt rsults and limits Prsnt rsults: Sarch for at Zus Prsnt rsults: Sarch for at H1 Prsnt rsults: Sarch for q at H1 Prsnt limits for q Conclusion and outlook J. Bckr Sarch for Excitd Quarks Uni Zurich

3 Excitd frmions and comositnss Family structur and masss of frmions Quarks Ltons u (u) c (charm) t (to) d (down) s (strang) b (bauty) (lctron) µ (muon) τ (tau) ν ( nutrino) ν µ ( µ nutr.) ν τ ( τ nutr.) Masss gtting biggr Exlanation: Comositnss of Quarks and Ltons? Consqunc: Existnc of xcitd Stats of Quarks and Ltons Comositnss Scal: Excitd Frmion Masss: Lowst xcitation stats: TV rgion TV rgion fw hundrd GV HERA (H1 and Zus) allows cntr of mass nrgis u to 320GV J. Bckr Sarch for Excitd Quarks Uni Zurich 1/12

4 Phnomnological framwork Assumtion: Excitd frmion F is comosit of a scalar and a sin 1 2 constitunt In our cas: F has sin 1 2, isosin sin 1 2 (lowst xcitation) Effctiv Thory: ffctiv Lagrangian (low nrgy rgion) PSfrag rlacmnts Couling of th xcitd frmion Gaug boson (g, Z/γ, W ± ) F SM coulings nw coulings L ff = 1 2Λ F R σ µν ( g f τ a 2 W µν a SU(2) + g f Y 2 B µν U(1) comositnss scal Couling constant: F + g s f s λ a 2 Ga µν SU(3) C ) F L + h.c. c γf f = 1 2 (f I 3 + f Y 2 ) limits for f ( or f / Λ ) J. Bckr Sarch for Excitd Quarks Uni Zurich 2/12

5 Production of xcitd frmions Singl roduction PSfrag rlacmnts LEP: + Collidr + γ + q or g PSfrag rlacmnts CDF: Collidr Pair roduction PSfrag rlacmnts + LEP: + Collidr q or g PSfrag rlacmnts CDF: Collidr with gluons (.g. LHC) q or g q g Z/γ g q or g q F F F F J. Bckr Sarch for Excitd Quarks Uni Zurich 3/12

6 Production and dcays of xcitd frmions at HERA, ν m * γ / Z γ, Z, W ν,, x ν * W γ, Z, W m ν x m q γ / Z q * q γ, Z, W, g x J. Bckr Sarch for Excitd Quarks Uni Zurich 4/12

7 Ovrviw of th q sarch analysis MC signal saml: Evnt Gnrator FERMION (Mari-Claud Cousinou) Simulatd dtctor rsons from H1Sim MC background saml: NC DIS vnts with gnrator DJANGOH Photoroduction vnts with gnrator PYTHIA H1 data: Last analysis on q usd 37 b 1 intgratd luminosity of data Now is mor thn 100 b 1 intgratd luminosity of data availabl Find cuts to sarat signal and background Driv limits J. Bckr Sarch for Excitd Quarks Uni Zurich 5/12

8 H1 dtctor and th q dcay signatur Signatur: 1 hadronic jt 1 hoton 1 lctron (can b at low angl) γ / Z q * x q γ, Z, W, g Hadronic jt ± mnts Photon Elctron R Imortant arts of th dtctor: LAr Calorimtr Tracking systm Z J. Bckr Sarch for Excitd Quarks Uni Zurich 6/12

9 Standard modl background rocsss Nutral currnt DIS: Z 0 xchang IsolatdPSfrag scattrd rlacmnts lctron, ν On or mor cntral jts Proton rmnant nrgy around bami x γ, Z 0, W ±! X NC DIS with initial or final stat radiation: Extra hoton coming from initial or final stat Problm if lctron vanishs through bami lctron ± mnts Photon lctron Hadronic jt J. Bckr Sarch for Excitd Quarks Uni Zurich 7/12

10 Prsnt rsults: Sarch for at Zus, ν * γ / Z γ, Z, W, x Invariant mass of dtctd lctron and hoton J. Bckr Sarch for Excitd Quarks Uni Zurich 8/12

11 Prsnt rsults: Sarch for at H1 Invariant masss for diffrnt dcay channls vnts H1 * analysis H1 data SM background + γ (a) vnts H1 * analysis (b) H1 data SM background + 2jts invariant mass (GV) invariant mass (GV) vnts H1 * analysis (c) H1 data SM background ν + 2jts * γ / Z, ν γ, Z, W invariant mass (GV), x J. Bckr Sarch for Excitd Quarks Uni Zurich 9/12

12 Prsnt rsults: Sarch for q at H1 γ / Z q * q γ, Z, W, g x Invariant mass of dtctd jt and hoton J. Bckr Sarch for Excitd Quarks Uni Zurich 10/12

13 Prsnt limits: Sarch for q at H1 f / Λ (GV -1 ) DELPHI BR(q * q γ)=1 H1 f = f, f s = 0 Assumtion: f = f and f s = 0 no strong couling q * q γ q * q Z q * q W q * all channls q * Mass (GV) Extnsion of rsults from DELPHI by H1 f H1 Assumtion: f = f and Λ = M(q ) Rsults CDF (TVatron) strong couling in gnration rocss q * Mass (GV) H1 is mor snsitiv for small f s than CDF J. Bckr Sarch for Excitd Quarks Uni Zurich 11/12

14 Conclusion and outlook H1 can contribut limits at rgions of small q masss and small f s q analysis should b ushd at H1 bcaus CDF will dlivr nw rsults in th nar futur, too A lot of work ahad J. Bckr Sarch for Excitd Quarks Uni Zurich 12/12