Leptophilic new physics at the LHC

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Mikael Chala, VI CPAN Days, Sevilla

Mikael Chala ,

F. del Águila, Y. Yamamoto & J. Santiago (Universidad de Granada)

Based on

JHEP 1403 (2014) 027 & CAFPE-183/14

Leptophilic new

physics at the LHC

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Outline

The properties of leptophilic physics Current and future constraints

The limit of large masses

The nature of LNV scalars

Current and future constraints Conclusions

Leptophilic Z'

LNV scalar interactions

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Structure of leptophilic physics

Scalar 1

non-renormalizable lepton interactions

Vector 1 0

renormalizable lepton interactions

0

lll & llll signals as other new physics (to be discussed later)

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The renormalizable lagrangian of a leptophilic Z'

quantum number

1 1 -1 -1

anomaly free, Foot et al '94

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Mikael Chala, VI CPAN Days, Sevilla Mikael Chala, VI CPAN Days, Sevilla

LEP and LFV constraints

Precision measurements at Z pole

& above Z pole

Carena et al '04

Sindrum & PSI

Bell Collab.

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Mikael Chala, VI CPAN Days, Sevilla Mikael Chala, VI CPAN Days, Sevilla

LEP and LFV constraints

Parameterize the lagrangian (up to taus) by means of and

Cross section at the LHC given (to very good accuracy) by

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Test these interactions in lll and llll final states

Order fb at both LHC and ILC

Z-Z' mixing effects

on Drell-Yan are model dependent

Aguila, Coughlan & Quirós '88, Holdom, '91, Aguila, Masip &

Perez-Victoria, '95

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LHC reach

is also shown in the pictures, while

g-2 is only relevant for small masses

[Ma, Roy & Roy, '02]

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ILC reach (taus are also considered)

Both Z' decays are included in any case, but a priori

they can be splitted

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Test these interactions in lll and llll final states

Order fb at both LHC and ILC

Z-Z' mixing effects

on Drell-Yan are model dependent

Aguila, Coughlan & Quirós '88, Holdom, '91, Aguila, Masip &

Perez-Victoria, '95

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The limit of large Z' mass

Can be also

induced by

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Experiment scale

Different doubly-charged scalar at a lower scale can mix with

LNV extensions of the SM can

accommodate neutrino Majorana masses

Only three scalar fields at the renormalizable level

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After integrating out scale, higher multiplets ( ) couple to same-sign leptons via Yukawa-like interactions

and suppressed by powers of

Off-diagonal couplings suppressed by LFV bounds

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What is the phenomenology of these scalars?

VS

What current analyses assume (see-saw II)?

ATLAS

Eur.Phys.J

C72-2244

Eur.Phys.JCMS

C72-2189

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Using current CMS three- and four-lepton analyses, set

bounds on LNV processes mediated by doubly-charged scalars

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Using current CMS three- and four-lepton analyses, set

bounds on LNV processes mediated by doubly-charged scalars

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Conclusions

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There are no signals of new physics at the LHC. So, either new physics is at a larger scale, or it is somehow elusive.

Concerning leptophilic physics, LHC and ILC will be

complementary, although no much room for ILC discovery.

Higher scales can not be successfully tested in both colliders, but LNV could be efficiently searched for.

Thank you!

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Backup

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Can we discriminate among the different multiplets?

LNV can be very difficult to be established at the LHC But doubly-charged scalars can be still present

Discrimination is possible if two-body decays dominate

Measure the neutral cross section using

four-lepton events

(and observe signals of a charged channel)

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How well can we discriminate among the different multiplets?

14 TeV, L = 100, 300, 3000/fb - Only light

leptons

- Light leptons and taus

- Light leptons and Ws

- Light leptons taus and Ws