Measuring the SUSY breaking scale at the LHC in the slepton NLSP scenario of GMSB models

Abstract

A bstractW e report a study on the m easurem ent of the SU SY breaki ng scal e p F i n the fram ework of gauge-m edi ated supersym m etry breaki ng (G M SB ) m odel s at the LH C .T he work i s focused on the G M SB scenari o w here a stau i s the next-to-l i ghtest SU SY parti cl e (N LSP) and decays i nto a gravi ti no w i th l i feti m e c N LSP i n the range 0. 5 m to 1 km . W e study the i denti cati on ofl ongl i ved sl eptons usi ng the m om entum and ti m e of i ght m easurem ents i n the m uon cham bers of the AT LA S experi m ent. A real i sti c eval uati on ofthe stati sti caland system ati c uncertai nti es on the m easurem entofthe sl epton m assand l i feti m e i sperform ed,based on a detai l ed si m ul ati on of the detectorresponse.A ccessi bl e range and preci si on on p F achi evabl e w i th a counti ng m ethod are assessed. M any features ofouranal ysi s can be extended to the study ofdi erenttheoreti cal fram eworks w i th si m i l ar si gnatures at the LH C .

Gravitino dark matter and cosmological constraints

“…The gravitino appears naturally as the LSP in well-motivated SUSY breaking schemes [1,3,5] and the lighter stau as the lightest standard model superpartner in high-energy frameworks. Scenarios with the gravitino LSP and the stau NLSP are particularly promising: The gravitino LSP is a natural dark matter candidate and the longlived stau NLSP could provide striking signatures at future colliders [36,37,38,39,40,41] which could lead to experimental evidence for gravitino dark matter [42,45,25].…”

“…Assuming the gravitino LSP scenario, this m˜l value can be used to refine the upper bound on m G from the cosmological constraints presented in this paper. If, in addition, the lifetime of the NLSP, τ˜l, can be measured, one will be able to determine the mass of a possible gravitino LSP from the SUGRA prediction for τ˜l [41,42]. We have emphasized that an experimental determination of (m G , m˜l) would impose upper limits on the gravitino density from NLSP decays, Ω NTP G , and thereby improve the upper limit on the reheating temperature after inflation T R .…”

“…For phenomenology at future colliders, the SUSY scenario with a charged slepton NLSP and an extremely weakly interacting LSP such as the gravitino is particularly promising [36,37,38,39,40,41,42,22,43,44,45,25]. Because of its long lifetime, the charged slepton NLSP would appear as a (quasi-)stable particle.…”

“…If some of the charged slepton NLSPs would decay already in the detectors, the statistical method proposed in Ref. [41] could allow one to measure the lifetime of the slepton NLSP. Since this lifetime is governed by the 2-body (95% CL) [52,7], where mg(M Z ) = 0.7 TeV (top), 1.4 TeV (middle), and 5 TeV (bottom).…”

“…Indeed, the lighter stau τ 1 can appear naturally as the lightest standard model superpartner in frameworks in which the spectrum at low energies is derived from SUGRA predictions at the scale of grand unification. Scenarios with a gravitino LSP and a long-lived charged slepton NLSP are also particularly promising for phenomenology at future colliders [36,37,38,39,40,41,42,22,43,44,45,25,46].…”