G. Moreau Laboratoire de Physique Thorique, Orsay, France Based on - PowerPoint PPT Presentation

« Electroweak Breaking After First Three Years at the LHC » Aspects of Aspects of Higgs Higgs rate rate fi fi ts ts G. Moreau Laboratoire de Physique Théorique, Orsay, France Based on arXiv:1210.3977 (will be updated tuesday) & Work in progress with A. Djouadi Warsaw - 17/03/2013 -

1/24 ¡ Outline A - Focusing on new fermions I) The Higgs fits with Extra-Fermions II) Constraining single Extra-Fermions B – The interests of rate ratios I) Get rid of the theoretical uncertainty II) Fitting ratios of signal strengths

2/24 ¡ A - Focusing on new fermions I) The Higgs fits with Extra-Fermions Today : The LHC has discovered a resonance of ~ 125.5 GeV it is probably the B.E.Higgs boson => EWSB mechanism + Tevatron and LHC provide 58 measurements of the Higgs rates = new precious source of indirect information on BSM physics nature of the EWSB : within the SM or a BSM context !?

3/24 ¡ On the theoretical side: New fermions arise in most (all?) of the SM extensions, – little Higgs [fermionic partners] – supersymmetry [gauginos / higgsinos] – composite Higgs [excited bounded states] – extra-dimensions [Kaluza-Klein towers] – 4 th generations [new families] – GUT [multiplet components] – etc … What are the present constraints on extra-fermions from all the experimental Higgs boson results ?

4/24 ¡ Effective approach : Corrections on the Higgs couplings from any extra-fermions (via mixing, new loops) t L t R − c b Y b h ¯ L h = − c t Y t h ¯ b L b R − c τ Y τ h ¯ τ L τ R α α s π v h F µ ν F µ ν + C hgg 12 π v h G aµ ν G a + C h γγ µ ν + h . c . Modifications of Y f Yukawa couplings via ( f ’) EF mixings : SM ¡ f R f ’ ¡ h ¡ f ’’ ¡ f L SM ¡

5/24 ¡ b’ , q 5/3 , … C hgg = 2 C ( t ) A [ τ ( m t )] ( c t + c gg ) + 2 C ( b ) A [ τ ( m b )] c b + 2 C ( c ) A [ τ ( m c )] , b’ , q 5/3 , … C h γγ = N t t A [ τ ( m t )] ( c t + c γγ ) + N b b A [ τ ( m b )] c b + N c τ A [ τ ( m τ )] c τ + 1 c A [ τ ( m c )] + N τ c c c c 6 Q 2 6 Q 2 6 Q 2 6 Q 2 8 A 1 [ τ ( m W )] ,

6/24 ¡ Higgs production cross sections over their SM expectations : � 2 � � � ( c t + c gg ) A [ τ ( m t )] + c b A [ τ ( m b )] + A [ τ ( m c )] σ gg ! h σ h¯ tt ' | c t | 2 , ' σ SM � 2 σ SM � � � A [ τ ( m t )] + A [ τ ( m b )] + A [ τ ( m c )] h¯ gg ! h tt Higgs partial decay widths over the SM predictions (no new channels) : � 2 � 1 � 4 A 1 [ τ ( m W )] + ( 2 3 ) 2 ( c t + c �� ) A [ τ ( m t )] + ( � 1 3 ) 2 c b A [ τ ( m b )] + ( 2 3 ) 2 A [ τ ( m c )] + 1 � 3 c ⌧ A [ τ ( m ⌧ )] Γ h ! �� ' � 2 Γ SM � � 1 4 A 1 [ τ ( m W )] + ( 2 3 ) 2 A [ τ ( m t )] + ( � 1 3 ) 2 A [ τ ( m b )] + ( 2 3 ) 2 A [ τ ( m c )] + 1 � 3 A [ τ ( m ⌧ )] h ! �� Γ h ! ¯ Γ h ! ¯ ⌧⌧ bb ' | c b | 2 ' | c ⌧ | 2 , Γ SM Γ SM h ! ¯ bb h ! ¯ ⌧⌧

7/24 ¡ Measured signal strengths all of the form (exp. selection efficiencies) : ✏ gg ! h | p ✏ gg ! h | p ✏ gg ! h | p s,c,i � SM s,c,i � SM ✏ hqq ✏ h¯ � gg ! h | s + hqq | s + ✏ hV hV | s + tt | s tt s,c,i � h¯ B h ! XX µ p s,c,i ' ✏ gg ! h | p ✏ gg ! h | p ✏ gg ! h | p � SM ✏ hqq s,c,i � SM s,c,i � SM s,c,i � SM B SM gg ! h | s + hqq | s + ✏ hV hV | s + ✏ h¯ tt | s tt h¯ h ! XX � 2 ( c t , c b , c τ , c gg , c γγ ) d For the fit analysis, we define a function : ( µ p s,c,i � µ p s,c,i | exp ) 2 � 2 = X ( � µ p s,c,i ) 2 p,s,c,i

8/24 ¡ Taking ¡the ¡latest ¡experimental ¡results… ¡

9/24 ¡ @ a D @ b D 10 10 Higgs fit results : 0.5 1 5 5 c t = 1.5 c t = 1 c b = 1 c gg c t = 1 c b c gg = 0.75 0.5 1 c t = 2.5 t' ( 3 free SM 0 0 68 % 95 % param.) 95 % 99 % 99 % - 5 - 5 - 3 - 2 - 1 0 1 - 4 - 3 - 2 - 1 0 1 2 c gg c gg @ c D @ d D 40 15 c b = 10 c t = 1 10 20 + + 99 % 95 % 5 0.5 c gg 1 c gg c t = 1.5 c t = 1 c b = 2.08 b' 0 68 % b' - 1.9 c t = 1.8 95 % 0 + + 99 % f, ∆ χ 2 = χ 2 − χ 2 68 % 1 min , 95 % - 20 gg - 5 γγ e χ 2 99 % min = 52 . 36. - 10 - 40 - 4 - 3 - 2 - 1 0 1 2 - 10 - 5 0 5 10 c gg c gg

10/24 ¡ « 3 conclusions for this first fit… » } * The SM point ( ) does not belong to the 1 σ region e, χ 2 SM = 57 . 10 * Determination of and relies on the knowledge of Y t EF ( c t ) = 1; c gg = 0; c γγ EF ( c b ) B(h VV) compensated by σ gg->h i.e. * Y b = 1; c gg Y b cannot be determined by the (previous) Higgs fit suggestion : avoid compensations by measuring estigate the b (or equivalently the bottom y, h ! ¯ qq ! h¯ bb and gg ! h¯ bb. cesses, ¯ bb

10 10 Higgs fit 8 8 results : 6 6 0.5 0.5 1 1 c t = 1.5 c t = 1.5 4 4 c gg c gg c t = 1 c b c t = 1 c b = 1 = 0.75 2 2 ( 3 free 99 % SM t' 0 0 param.) 95 % 68 % 68 % 95 % - 2 - 2 99 % - 4 - 4 - 3 - 2 - 1 0 1 - 3 - 2 - 1 0 1 c gg c gg AFTER 10 MORIOND... 10 8 + + 6 0.5 0.5 1 1 c t = 1.5 5 c t = 1.5 4 c gg c gg c t = 1 c b = 1.09 c b c t = 1 = 2 2 f, ∆ χ 2 = χ 2 − χ 2 min , 0 0 b' b' + + gg γγ 68 % 95 % - 2 e χ 2 min = 52 . 36. 95 % 99 % 99 % - 4 - 5 - 3 - 2 - 1 0 1 - 3 - 2 - 1 0 1 2 c gg c gg

11/24 ¡ | c τ | Varying the last parameter : 10 10 10 8 8 8 + + 6 6 0.5 6 0.5 0.5 1 1 c t = 1.5 1 c t = 1.5 c t = 1.5 4 4 4 c gg c gg c gg c b c t = 0.05 c b = 1.09 c t = 1.6 = 1.09 c t = 1 c b = 1.09 2 2 2 0 0 0 + + b' 68 % 68 % - 2 68 % - 2 - 2 95 % 95 % 95 % 99 % 99 % 99 % - 4 - 3 - 2 - 1 0 1 - 3 - 2 - 1 0 1 - 3 - 2 - 1 0 1 c gg c gg c gg

12/24 ¡ II) Constraining single Extra-Fermions Single extra-fermion (starting approximation) => new loop-contributions : Y q 5 / 3 1  � C ( t 0 ) Y t 0 � c gg = m t 0 A [ τ ( m t 0 )] � C ( q 5 / 3 ) A [ τ ( m q 5 / 3 )] + . . .  � C ( t ) A [ τ ( m t )] /v m q 5 / 3  ✓ ◆ ✓ ◆ ◆ 2 Y t 0 ◆ 2 Y q 5 / 3 1  ✓ 2 ✓ 5 ` 0 Y ` 0 � q 5 / 3 A [ τ ( m q 5 / 3 )] � Q 2 c �� = � 3 m t 0 A [ τ ( m t 0 )] � N m ` 0 A [ τ ( m ` 0 )] + . . . c N t c Q 2 t A [ τ ( m t )] /v 3 3 m q 5 / 3 Q 2 � c �� (same color repres. as the top) q 0 � = � (2 / 3) 2 c gg � q 0

13/24 ¡ independently of Y q’ , masses, SU(2) L repres. � Q � pert. 99 � 10 (2 free parameters) 95 � 68 � 10 c t � 1 8 68 % c b 5 � 1 95 % c Τ � 1 6 99 % c ΓΓ c t = 1 l’ ¡ 4 c b = 1 c gg Q l ¢ = - 1 Q q � � 0 c gg = 0 0 2 � 1 � 3 0 2 � 3 - 2 � 4 � 3 8 � 3 5 � 3 � 7 � 3 � 5 - 2 - 1 0 1 2 � 2.0 � 1.5 � 1.0 � 0.5 0.0 c t c gg

AFTER independently of Y q’ , masses, SU(2) L repres. MORIOND... » Q » pert. 10 (2 free parameters) 99 % 95 % 68 % 10 c t = 1 8 c b = 1 5 99 % 95 % 68 % c t = 1 6 c gg c t = 1 4 c b = 1 c gg Q l ¢ = - 1 Q q ¢ = 0 c gg = 0 0 2 - 1 ê 3 0 2 ê 3 - 2 - 4 ê 3 8 ê 3 5 ê 3 - 7 ê 3 - 5 - 2 - 1 0 1 2 - 2.0 - 1.5 - 1.0 - 0.5 0.0 c t c gg

14/24 ¡ (1 free param.) For low-charge q’ , Ex Ex ts ts a-dys ysfe fermiophilia : ✓ − Y q 0 ◆ sign < 0 m q 0 … increasing the diphoton rates. e, q 5 / 3 ! tW + , s, q 8 / 3 ! tW + W + ,

15/24 ¡ Con onclus usion ions (A) Already non-trivial & generic constraints on extra-fermions from the Higgs rate fit : Potentially stringent constraints on extra-quark electric charges independently of the Yukawa’s, masses, SU(2) L representations Extra-dysfermiophilia for low-charge single q’ (colored as the top) The obtained plots can be used for any scenario with new fermions + Difficult and correlated determinations of some Yukawa couplings and parameters for the new loop-contributions to hgg , h γγ .

16/24 ¡ B – The interests of rate ratios I) Get rid of the theoretical uncertainty The ¡QCD ¡uncertainty ¡ ¡ (PDF, ¡ α s 2 ¡@ ¡LO, ¡scale ¡dependence) ¡ ¡on ¡the ¡ inclusive ¡Higgs ¡production ¡cross ¡section ¡reaches ¡ ¡~ ¡15-­‑20% ¡ ¡ [LHCHWG] ¡ δ exp N evts . ( pp → H → XX ) ..it ¡affects ¡ µ XX | exp = i � X � i σ i ( H ) BR( H → XX ) | SM × L the ¡ ¡ ¡ ¡’s ¡fit ¡ µ XX � δ th i � X � i σ i ( H ) BR( H → XX ) µ XX | th = i � X � i σ i ( H ) BR( H → XX ) | SM

17/24 ¡ Taking ¡ ¡ ¡ ¡ ¡ratios ¡can ¡allow ¡to ¡suppress ¡the ¡QCD ¡error ¡: ¡ µ XX δ exp exp = N evts . ( pp → H → XX ) i � Y � i σ i ( H ) | SM BR( H → Y Y ) | SM µ XX � � i � X N evts . ( pp → H → Y Y ) � i σ i ( H ) | SM BR( H → XX ) | SM µ Y Y � can ¡cancel ¡out ¡! ¡ � tH σ ( gg → t ¯ th = � X gg σ ( gg → H )+ � X VBF σ ( qq → Hqq )+ � X q → V H ) + � X HV σ ( q ¯ tH ) µ XX � t ¯ � tH σ ( gg → t ¯ gg σ ( gg → H ) + � Y VBF σ ( qq → Hqq ) + � Y q → V H ) + � Y � Y HV σ ( q ¯ tH ) µ Y Y � t ¯ Γ ( H → XX ) i � Y i σ i ( H ) | SM � Γ ( H → XX ) | SM × D XY ( c f , c V ) ( i � X Γ ( H → Y Y ) � i σ i ( H ) | SM Γ ( H → Y Y ) | SM