27,179 research outputs found
The Fate of Long-Lived Superparticles with Hadronic Decays after LHC Run 1
Supersymmetry searches at the LHC are both highly varied and highly
constraining, but the vast majority are focused on cases where the final-stage
visible decays are prompt. Scenarios featuring superparticles with
detector-scale lifetimes have therefore remained a tantalizing possibility for
sub-TeV SUSY, since explicit limits are relatively sparse. Nonetheless, the
extremely low backgrounds of the few existing searches for collider-stable and
displaced new particles facilitates recastings into powerful long-lived
superparticle searches, even for models for which those searches are highly
non-optimized. In this paper, we assess the status of such models in the
context of baryonic R-parity violation, gauge mediation, and mini-split SUSY.
We explore a number of common simplified spectra where hadronic decays can be
important, employing recasts of LHC searches that utilize different detector
systems and final-state objects. The LSP/NLSP possibilities considered here
include generic colored superparticles such as the gluino and light-flavor
squarks, as well as the lighter stop and the quasi-degenerate Higgsino
multiplet motivated by naturalness. We find that complementary coverage over
large swaths of mass and lifetime is achievable by superimposing limits,
particularly from CMS's tracker-based displaced dijet search and heavy stable
charged particle searches. Adding in prompt searches, we find many cases where
a range of sparticle masses is now excluded from zero lifetime to infinite
lifetime with no gaps. In other cases, the displaced searches furnish the only
extant limits at any lifetime.Comment: 36 pages, 10 figures, plus appendix and reference
Branching ratios of decays in the perturbative QCD approach
In this paper we calculate the branching ratios (BRs) of the 32 charmless
hadronic decays () by employing the perturbative
QCD(pQCD) factorization approach. These considered decay channels can only
occur via annihilation type diagrams in the standard model. From the numerical
calculations and phenomenological analysis, we found the following results: (a)
the pQCD predictions for the BRs of the considered decays are in the
range of to , while the CP-violating asymmetries are absent
because only one type tree operator is involved here; (b) the BRs of processes are generally much larger than those of ones due to
the large CKM factor of ; (c) since the behavior for
meson is much different from that of meson, the BRs of decays are generally larger than that of
decays; (d) the pQCD predictions for the BRs of B_c \to (K_1(1270), K_1(1400))
\etap and decays are rather sensitive to the value
of the mixing angle .Comment: 1+17 pges, 1 figure, refs. added and some clarifications made,
accepted for publication in Phys.Rev.
Heavy Higgs bosons and the 2 TeV boson
The hints from the LHC for the existence of a boson of mass around 1.9
TeV point towards a certain gauge
theory with an extended Higgs sector. We show that the decays of the boson
into heavy Higgs bosons have sizable branching fractions. Interpreting the
ATLAS excess events in the search for same-sign lepton pairs plus jets as
arising from cascade decays, we estimate that the masses of the heavy
Higgs bosons are in the 400--700 GeV range.Comment: 22 pages; v2: Eqs. 3.6 and 3.8 corrected, clarifications and
references adde
- β¦