New results for light gravitinos at hadron colliders: Fermilab Tevatron limits and CERN LHC perspectives

Abstract

We derive Feynman rules for the interactions of a single gravitino with (s)quarks and gluons/gluinos from an effective supergravity Lagrangian in nonderivative form and use them to calculate the hadroproduction cross sections and decay widths of single gravitinos. We confirm the results obtained previously with a derivative Lagrangian as well as those obtained with the nonderivative Lagrangian in the high-energy limit and elaborate on the connection between gauge independence and the presence of quartic vertices. We perform extensive numerical studies of branching ratios, total cross sections, and transverse-momentum spectra at the Fermilab Tevatron and the CERN LHC. From the latest CDF monojet cross section limit, we derive a new and robust exclusion contour in the gravitino-squark/gluino mass plane, implying that gravitinos with masses below 2 10 ÿ5 to 1 10 ÿ5 eV are excluded for squark/ gluino masses below 200 and 500 GeV, respectively. These limits are complementary to the one obtained by the CDF Collaboration, 1:1 10 ÿ5 eV, under the assumption of infinitely heavy squarks and gluinos. For the LHC, we conclude that supersymmetric scenarios with light gravitinos will lead to a striking monojet signal very quickly after its startup.

SUSY dark matter(s)

“…The single-gravitino production rate at LHC has been computed in [153] and it results in a visible monojet signal only for very light gravitino with mass well below 1 eV. Such a gravitino could only be considered as a subdominant hot DM component, since the case of dominant hot DM is excluded by large scale structure observations [154,155].…”

Associated production of light gravitinos in e + e − and e − γ collisions

“…Similar to (12), the fourmomenta and helicities of the external particles are defined in the eγ CM frame with β = 1 − m 2 eR /s. The following features of the amplitudes are worth noting:…”

“…(28) in [8] for the photino case, and also with Eq. (3) of [12] for the gluino associated process qq → gG after substitutions for the masses and the couplings as…”

“…Several studies on the associated gravitino productions have been performed so far, for instance,χ 0 1 -G productions in e + e − [5,6,7,8] and hadronic [8] collisions,ẽ-G productions in eγ collisions [9], andg-G [10,11,12] andq-G [11,12] productions in hadronic collisions. When the associated SUSY particle is the next-to-lightest supersymmetric particle (NLSP) and promptly decays into a SM particle and a LSP gravitino, the above production processes lead to particular collider signatures, such as γ + / E, e+ / E, and jet+ / E, where the missing energy is carried away by two gravitinos, and these signals set mass bounds on the gravitino and the other SUSY particles.…”

Light gravitinos at colliders and implications for cosmology

“…The high-energy collider signals of GMSB and gravitinos are well studied [50,51,[55][56][57][58][59][60][61][62][63][64][65][66][67][68][69]; for a review of current bounds, see Ref. [70].…”