Stefano(Giagu(for(the(ATLAS(and(CMS(Collaborations(

Sapienza(Università(di(Roma(and(INFN(Roma

Search(for(long9lived(

particles(at(LHC

LDMA(2015(>(Camogli(>(June(24>26(2015(

∗ Recipe(to(push(the(exploration(of(beyond(the(Standard(Model(effects(at(an(hadron(collider:(

∗ highest(luminosity(and(collision(energy(to(produce(heavy(states(and(small(production(couplings((

∗ detector,(triggers(&(analysis(techniques(able(to(cover(stealth(and(unusual(kinematical(configurations((very(

displaced(decays,(mass(degeneracies,(soft(objects(in(final(state(etc…)(

∗ ability(to(exploit(signature9based(searches(in(a(as(much(as(possible(model(independent(way(

∗ In(this(respect(long9lived(particles((LLP)(are(a(very(interesting(field(of(study:(

∗ occur(in(a(large(variety(of(new(physics(models((Hidden/Dark(sectors,(RPV9SUSY,(Split9SUSY,(GMSB,(AMSB(…)(

that(can(provide(solution(to(long9standing(issues(of(the(standard(model((naturalness,(dark(matter,(…)(

∗ often(come(with(striking(experimental(signatures:(opportunity(for(an(early(discovery(and/or(to(set(tight(

constraints(in(unexplored(regions(of(many(NP(models(

∗ Important(efforts(from(ATLAS(and(CMS(in(Run(1(resulting(in(a(large(number(of(signature9driven(searches,(

efforts(that(are(planned(to(be(extended(in(the(just(started(run(2(

Today(I’ll(review(recent(results(from(ATLAS(and(CMS(based(on(Run(1(data(… 2

Introduction

NOTE: not enough time to cover everything today. A full and daily updated list of all results from ATLAS and CMS, with details on each analysis, available here:

https://twiki.cern.ch/twiki/bin/view/AtlasPublic & http://cms.web.cern.ch/org/cms-papers-and-results

∗ Wide(diversity(of(decay(topologies(from(LLP(can(be(combined(in(a(limited(set(of(experimental(signatures(largely(

independent(from(the(details(of(the(underlying(new(physics(models:(

∗ displaced(vertices,(non9pointing(objects,(lepton9jets,(also(outside(the(inner9tracker(…(( (

( ( ( ( ( ⬅(long(lived(neutral(particles(decaying(in(leptons(and(hadrons(

∗ anomalous((kinked,(disappearing,(…)(tracks,(particles(sometime(stopped(in(the(detector(that(decays(in(different(bunch(

crossing(after(a(relatively(long(time(…(( ( ⬅((very)(long9lived(charged(particles(

∗ long(time9of9flight,(large(dE/dx(( ( ( ⬅(low9velocity(massive(charged(particles(with(high(pT(

∗ Range(of( lifetimes(explorable(with(the(detectors(maximised(categorising(the(searches(in(three( (broad(groups(of(

analyses,(with(significant(overlap(for(some(models(and(searches:(

∗ inner(detector9based(searches(

∗ calorimeter9based(searches(

∗ muon(spectrometer9based(searches((

∗ Analysis(design(and(Interpretation(:(

∗ first(generation(of(searches(optimised(and(interpreted(in(the(context(of(specific(benchmark(models(/(simplified(models((SUSY,(

Hidden(Valley(/(Dark(Sectors,(Exotic(Higgs(scenarios(…)(

∗ in(practice(the(results(can(be(re9interpreted(in(the(context(of(many(different(models((

∗ to(facilitate(this(step(a(large(set(of(additional(informations((efficiencies/acceptances(per(object(as(a(function(of(the(most(

significative(kinematical(observables,(detailed(trigger/selection(criteria(…)(are(provided(by(ATLS(and(CMS 3

Experimental(signatures(at(LHC

4

…(and(LLP(analysis(features

∗ typically(common(to(all(LLP(searches(in(ATLAS(and(CMS:(

∗ Standard(Model(backgrounds(generally(small,(but(instrumental(background(may(be(an(

issue(

∗ searches(require(full(understanding(of:(

∗ background(from(b/c/s(mesons(for(decays(at(small(distance(from(IP,(in(particular(at(the(edge(of(their(

decay(range(

∗ material(effects(

∗ alignments(

∗ detector(timing(

∗ non9collision(background((cosmic(rays(and(beam(halo(muons(can(emulate(very(displaced(signals)((

∗ Control(samples(in(data(crucial(to(keep(under(control(all(these(sources(of(uncertainty(

∗ sometime(standard(triggers(&(reconstruction(may(be(not(optimal(for(such((“non(

conventional”(signatures(→(large(amount(of(work(needed(to(develop(custom(

triggers/reconstruction(algorithms

5

Experimental(tools

ATLAS(and(CMS(similar(in(many(respects(but(also(with(complementary(features(for(exotic(LLP(detection:(

CMS:((

9 excellent(reconstruction(of(secondary(vertices(in(the(inner9tracker(up(to(~30cm(from(the(IP(((

9 fast(response(and(excellent(timing(resolution(of(ECAL(→(sensitive(to(time9of9flight(effects(inside((ECAL(volume(

ATLAS:(

9 segmented(ECAL/HCAL(→(can(measure(impact(parameters(for(unconverted(photons((

9 air9core(and(standalone(tracking(in(a(large(muon(system(→(excellent(performance(for(very(highly(displaced(

vertices(reconstructed(with(the(muon(system

SM HV

med

iato

r

!HLSP

!HLSP 6

Hidden(Sectors

Models(with(hidden(sectors(may(offer(a(way(for(new(physics(to(escape(the(strict(limits(placed(by(prompt(

searches(at(colliders(and(from(precisions(measurements.((

New( particles( in( fact( may( have( not( been( observed( in( LHC( collisions( yet( because( “hidden”( in( sectors(

separate(from(and(only(weakly(coupled((with(the(Standard(Model.

Hidden(Valley(models(are(a(general(class(of(theories(that(predict(neutral,(

long9lived(particles(

9 Hidden(Valley(particles(are(SM9neutral,(but(some(communication(

allowed(via(mediators((Higgs,(Z´,LSP,(...)(

9 hidden(LSP,(stable(in(the(hidden(sector,(can(decay(back(to(SM(

particles(again(via(mediator(

9 common(across(different(HV(models:((

9 long(lifetimes:(connected(with(the(barrier(between(the(two(

sectors((mass/energy,(coupling/mixing,(…)((

9 unique(topological(signatures(and(almost(background(free(

processes(→(early(discovery(potential(

7

Hidden(Valley:(neutral(LLP(→(jets

ATLAS(recent(search(for(displaced(jets(topologies(predicted(in(Hidden(Valley(

models:(

9 benchmark(models(used(for(optimisation(and(interpretation:(Hidden(Valley(with(Higgs(and(Z’(

communicators,(stealth9SUSY(models(

Two(different(searches:(

9 Trackless(Jets(analysis:(aim(at(decays(of(LLP(inside(calorimeters(

9 Displaced(Vertices(in(MS(and(ID(analysis:(aim(at(decays(in(the(inner9tracker(or(in(muon(spectrometer

Φ:(Higgs(scalar((

(non(necessarily(SM)

8

Hidden(Valley:(neutral(LLP(→(jets

Trackless(Jets(Analysis:(

looks( at( displaced( jets( produced( from( light( (1009140( GeV)( higgs( boson( decays( to( a( pair( of(

neutral(LLPs((10940(GeV)(which(in(turn(decay(in(fermions((mostly(b9quark)((

9 specialised(calorimeter(trigger(to(select(decays(into(the(hadron(calorimeter(

9 select(narrow(jets(with(an(anomalous(HAD/EM(energy(ratio((log10(EHAD/EEM)>1.2()(and(ET>60(GeV(

9 no(inner(detector(activity(pointing(toward(the(jets((track9less(jets):(no(charged(tracks(with(pT>1(GeV(in(ΔR<0.2(

9 Dominant(backgrounds((estimated(with(data(driven(methods):((

9 SM(multi9jet(events(

9 instrumental(backgrounds:(cosmic(rays,(beam(halo

PLB

743

(201

5) 1

5-34

log10(EH/EEM)Jet(Timing

9

Hidden(Valley:(neutral(LLP(→(jets

Displaced(Vertices(in(MS(and(ID(Analysis:(

9 two(specialised(triggers:(

9 MS:(Muon(RoI(→(cluster(of(standalone(muons(reconstructed(by(L1(trigger(in(a(cone(of(ΔR<0.4,(

isolated(in(the(calorimeters(and(inner9tracker(

9 ID:(jet(+(MET((((→(optimised(for(events(with(large(jet(multiplicity((Hidden(Valley(with(Z’(

mediator)(

9 custom(algorithms(developed(to(reconstruct(standalone(vertices(in(the(muon(spectrometer(and(

very(displaced(vertices(in(the(inner9tracker((developed(in(synergy(with(the(SUSY9LLP(DV(analysis)

Muon(RoI(

Trigger

ID(DVertex(

algorithm

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504.

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HV(with(scalar((

communicator Stealth(SUSYHV(with(Z’(communicator 10

Hidden(Valley:(neutral(LLP(→(jets

Results:(9 no(evidence(of(signals(in(the(whole(Run1(statistic(@(8(TeV(

9 exclusion(expressed(as(95%(CL(upper(limits(on(σ×BR/σSM(as(a(function(of(πV(proper(decay(length(and(for(

different(assumptions(on(the(communicator(mass

PLB

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HV(with((

Higgs((125(GeV)((

communicator

11

Hidden(Valley:(displaced(decays(in(jets/leptons

Similar(search(for(displaced(jets(and(leptons(performed(by(CMS:(9 look(for(two(isolated(high(pT(leptons(or(jets(that(form(a(good(vertex(in(the(ID(significantly(displaced(from(primary(vertex(

9 analysis(improved(recently,(by(looking(at(displaced(di9muons(reconstructed(standalone(in(the(MS(to(extend(

explored(range(of(lifetimes((a(factor(~×2(on(the(lifetime(upper(limits)(

Interpretation(of(results:(

9 Hidden(Valley(with(Higgs(communicator(motivated:(higgs(decay(in(two(long9lived(spin90(bosons(X(decaying(in(a(pair(of(

leptons(or(jets:(H→XX→4l/4jets(

9 RPV(SUSY(motivated:(long(lived(neutralino(from(squark(decay,(with(q→qχ,(χ→llν/jets+X

Phy

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9 Expected(in(different(extensions(of(the(SM:(

9 Dark(sectors:(dark9SUSY:(h(→(2n1,(n1→nd+γd,(γd(→(2e/2μ/2h(

9 connection(to(the(hidden(sector(via(kinetic(mixing((ε),(ε(determines(

lifetime(of(dark(photons((

9 predict(low(mass(dark(photons(decays(to(very(collimated(pair(of(

electrons/muons/hadrons(

9 BR(γd(→(2μ)(sizeable(O(40%)((for(mγd>2mμ((

9 NMSSM:((h(→(2a(+(X(→(4μ(+(X(

9 able(to(reduce(amount(of(fine(tuning(in(MSSM(

9 extended(higgs(sector:(3(CP9even(neutral((h1,2,3,(2(CP9odd(neutral(a1,2(and(2(

charged(higgs(h±(

9 h1,2(→(2a1(((h1,2(can(be(the(observed(Higgs(at(125(GeV)(

9 a1(is(light(and(couple(to(fermions(proportionally(to(the(fermion(mass((

9 BR(a1(→(2μ)(substantial(if(2mμ<ma1<2mτ((

9 If(ma(≪(mh(⇒(experimental(signature:(collimated(jets(of(muons12

Dark(Sectors:(muon9jets

portal to hidden sector: ex. higgs

hidden particles decay back to SM: ex. dark-photons to collimated pair of leptons

Light( hidden( particles( from( heavy( mediators( decays( may( be( very( boosted( in( the( lab( frame(

producing(collimated(decay(products,(called(lepton9jets.(

CMS(search(for(pair(production(of(new(light(bosons(((((((((((decaying(into(collimated(jets(of(muons:((h(→(2a(+(X(→(4μ(+(X

arX

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95%(CL(upper(limits(on(σ×BR(for((

NMSSM(scenario(VS(h1,h2(mass

observed(in(20.7(fb91:((((1(event(

expected(from(SM(BG:(2.2±0.7(events13

Dark(Sectors:(muon9jets

Selection:(

9 4(muons(with(pT>8(GeV(all(consistent(with(originating(from(the(same(PV(

9 2(oppositely(charged(muon(pair(with(m2μ<5(GeV,((isolated(in(the(inner9tracker(

9 each(pair(should(form(a(good(vertex(with(vertex(probability(>(1%(OR(ΔR(2μ)<0.01(

9 no(restrictions(on(the(number(of(additional(muons

signal(region(

m1≃m2((within(detector(resolution)

expected(SM(BG(

2mμ<m1,m2<2mτ

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P 11

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9 Triggers:((

9 muon9LJ:(3MU6(standalone:(low(pT,(based(only(on(muon(spectrometer(

9 e/had9LJ:(jet(with(low(ET(threshold((35(GeV)(+(unbalanced(EHAD/EEM(

ratio(→(efficient(for(decays(inside(the(hadron(calorimeter(

9 Background(processes:(

9 QCD(multi9jet:(controlled(with(requirements(on(EM(energy(fraction,(

isolation(and(transverse(shape(of(jets(

9 estimated(via(data9driven(methods((ABCD)(

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and(timing(of(the(energy(deposit(in(the(hadron(calorimeter(

9 estimated(using(events(collected(in(empty(bunch9crossing

Signal(Region

Isolation9ID

ATLAS(search(optimised(for(displaced(lepton9jets:(

9 model(independent(strategy(starting(from(topological(definition(of((lepton(jets((

9 efficient(for(lepton9jets(produced(by(multiple(dark9photons(collimated(decays(in(ee/μμ/hadrons

MUON EL/HAD

ATLAS (90% CL)

15

Dark(Sectors:(displaced(lepton9jets

σ×BR(limits(interpreted(as(exclusion(regions(in(the(

(ε,mγd)(plane(in(the(context(of(the(Vector(portal(model

Excluded c⌧ [mm]

BR(10%)

H ! 2�d +X 14 c⌧ 140

H ! 4�d +X 15 c⌧ 260

Results:

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11 (2

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088

,

ATLAS(20.3(fb91(@(8(TeV

16

Dark(Sectors:(dark9Z

Heavier(dark(states(also(directly(searched(by(ATLAS(in(a(model9independent(search(for(prompt(h→ZZd→4l(

9 in(order(to(use(SM(H9>4l(results,(search(restricted(to(15(GeV(<(mZd(<(mH(125(GeV)/2((

9 discriminating(observable:(m34(mass(spectrum((

9 search(for(a(local(excess(consistent(with(the(decay(of(a(narrow(Zd(resonance((

9 dominant(backgrounds:(SM(h→ZZ*→4l,((non(resonant(ZZ*→4l(and(Z+jet,(tt

arX

iv:1

505.

0764

5

absence(of(signal(in(data(interpreted(in(two(benchmark(scenarios:(

9 vector9portal:(dark9vector(bosons(coupled(via(kinetic(mixing(with(the(hypercharge(of(the((Z(boson(

9 mass9mixing:(SM(extended(with(a(Zd(and(an(additional(higgs(doublet,(resulting(in(a(mass(mixing(between(SM(higgs(and(the(

dark9vector(boson((w/o(assuming(direct(coupling(between(Zd((SM)

Limits(on(kinetic(mixing(parameter(ε

17

Summary(of(HV/DS9LLP(searches(

18

SUSY(inspired(LLP(Searches:(displaced(vertices

9 sensitivity(to(a(wide(variety(of(models((SUSY(RPV,((split9SUSY,(GMSB,(…)(achieved(by(ATLAS(and(

CMS(by(looking(at(displaced(decays(of(leptons,(jets(and(photons

non(pointing(photons

displaced(di9jets(

displaced(di9leptons(

displaced(vertices

ATLAS: Phys. Rev. D 90, 112005 (2014)

ATLAS: arXiv:1504.05162

CMS: Phys. Rev. D 91 (2015) 012007

CMS: Phys. Rev. D 91 (2015) 052012

CMS: Phys. Rev. Lett. 114, 061801 (2015)

GMSB

displaced(e+μ

∗ Search( for( BSM( effects( in( long9lived( particles( signatures( is( a( very( active( field( of(

study(at(LHC(

∗ unusual( topologies( offers( a(means( for( new(physics( to( escape( the( strict( limits(

placed(by(prompt(searches(and(at(the(same(time(a(great(potential(for(discovery((

∗ excellent( progress( in( analysis( techniques( and( interpretative( tools( have( been(

made(from(the(start(of(LHC(run(1(to(today,(resulting(in(tight(constraints(on(NP(

effects(at(LHC(

∗ LHC(Run(2( is( just(started,(higher(center(of(mass(energy(and( increased( integrated(

luminosity( will( allows( to( reach( for( greater( mass( and( to( test( smaller( couplings/

mixing( parameters,( sensibly( extending( the( reach( of( ATLAS( and( CMS( in( terms( of(

final(states(and(decay(lengths(…(

…(maximising(the(NP(discovery(potential(of(LHC19

Outlook(&(conclusions