tesis - bib-pubdb1.desy.debib-pubdb1.desy.de/record/209420/files/presentation_0.pdf · title: tesis...

Mikael Chala (DESY)in collaboration with F. del Águila, A. Santamaria

and J. Wudka. Based on 1311.1510 and 1305.3904.

BLV2015, UmassAmherst, April 29, 2015

Colliders Signatures ofLNV Higgs Sectors

The Standard Model is very strong

TeV scale

valid u

p t

o

Renormalizable

Stable vacuumDegrassi et al., 1205.6497

...

Planck scale

ModelBLV2015, UmassAmherst, April 29, 2015

Majorana neutrinos...About Lepton Number Violation

Accidental symmetry broken byneutrino Majorana mass terms

decay

BLV2015, UmassAmherst, April 29, 2015

The natural scale of LNV scalars

TeV scale

valid u

p t

o

Planck scale

Natural assumption

BLV2015, UmassAmherst, April 29, 2015

The natural scale of LNV scalars

TeV scale

valid u

p t

o

Planck scale

Naturalassumption

del Águila et al,1204.5986, 1111.6960

Gustafsson et al,1212.4806

BLV2015, UmassAmherst, April 29, 2015

Outline

Distinguishing LNV scalars at the LHC RUN2

Observing LNV scalar interactions at the LHC?

A generic approach to LNV scalars

BLV2015, UmassAmherst, April 29, 2015

LNV extensions of the SM canaccommodate neutrino Majoranamasses

Only three scalar fields at therenormalizable level

BLV2015, UmassAmherst, April 29, 2015

Experiment scale

Different doubly-charged scalar

at a lower scale can mix with

LNV extensions of the SM canaccommodate neutrino Majoranamasses

Only three scalar fields at therenormalizable level

BLV2015, UmassAmherst, April 29, 2015

After integrating out scale, higher multiplets ( )

couple to same-sign leptons via Yukawa-like interactions

BLV2015, UmassAmherst, April 29, 2015

Either or

What about

Equivalent by the ec. motion and integration + others?

After integrating out scale, higher multiplets ( )

couple to same-sign leptons via Yukawa-like interactions

and suppressed by powers of

BLV2015, UmassAmherst, April 29, 2015

What is the phenomenology of these scalars?

VS

What current analyses assume (see-saw II)?

ATLASEur.Phys.JC72-2244

CMSEur.Phys.JC72-2189

BLV2015, UmassAmherst, April 29, 2015

Observing LNV interactions in simplest

models can be really hard

BLV2015, UmassAmherst, April 29, 2015

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

bounds on LNV processes mediated by doubly-charged scalars

BLV2015, UmassAmherst, April 29, 2015

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

bounds on LNV processes mediated by doubly-charged scalars

BLV2015, UmassAmherst, April 29, 2015

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

bounds on LNV processes mediated by doubly-charged scalars

BLV2015, UmassAmherst, April 29, 2015

F. del Águila and M.C., 1311.1510

Efficien

cies in

%

Can we discriminate among the different multiplets?

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

Discrimination is possible if two-body decays dominate

Measure the neutral

cross section using

four-lepton events

arXiv:1305.3904

BLV2015, UmassAmherst, April 29, 2015

BLV2015, UmassAmherst, April 29, 2015

BLV2015, UmassAmherst, April 29, 2015

Distinguishing the

different

four-lepton channels

BLV2015, UmassAmherst, April 29, 2015

Distinguishing the

different

four-lepton channels

BLV2015, UmassAmherst, April 29, 2015

Distinguishing the

different

four-lepton channels

BLV2015, UmassAmherst, April 29, 2015

Distinguishing the

different

four-lepton channels

BLV2015, UmassAmherst, April 29, 2015

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

Águila, MC, Santamaría, Wudka, '13

BLV2015, UmassAmherst, April 29, 2015

Doublet caseSinglet case

BLV2015, UmassAmherst, April 29, 2015

It is a background of

Charged signals VS neutral current backgrounds

Cut here mainly signal

BLV2015, UmassAmherst, April 29, 2015

Conclusions

BLV2015, UmassAmherst, April 29, 2015

The SM describes nature to a very good accuracy, although there are still open questions: neutrino masses

LNV scalar interactions can be very difficult to be proved at the LHC

For the first time, bounds on LNV scalar interactions, and many other channels

Thank you!Even if no LNV, doubly-charged scalars can be distinguished in a large run of LHC

BLV2015, UmassAmherst, April 29, 2015