6,507 research outputs found
A Collider for the 750 GeV Resonant State
Recent data collected by ATLAS and CMS at 13 TeV collision energy of the LHC
indicate the existence of a new resonant state with a mass of 750 GeV
decaying into two photons . The properties of should be
studied further at the LHC and also future colliders. Since only decay channel has been measured, one of the best ways to extract
more information about is to use a collider to produce
at the resonant energy. In this work we show how a
collider helps to verify the existence of and to provide some of the
most important information about the properties of , such as branching
fractions of . Here can be , , or . We
also show that by studying angular distributions of the final 's in
, one can obtain crucial information
about whether this state is a spin-0 or a spin-2 state.Comment: ReTex, 12 page with 6 figures. Expanded discussion on distinguishing
spin-0 and spin-2 cases. Several figures adde
Some Predictions of Diquark Model for Hidden Charm Pentaquark Discovered at the LHCb
The LHCb has discovered two new states with preferred quantum numbers
and from decays. These new states can be
interpreted as hidden charm pentaquarks. It has been argued that the main
features of these pentaquarks can be described by diquark model. The diquark
model predicts that the and are in two separate octet
multiplets of flavor and there is also an additional decuplet
pentaquark multiplet. Finding the states in these multiplets can provide
crucial evidence for this model. The weak decays of b-baryon to a light meson
and a pentaquark can have Cabibbo allowed and suppressed decay channels. We
find that in the limit, for -spin related decay modes the ratio of
the decay rates of Cabibbo suppressed to Cabibbo allowed decay channels is
given by . There are also other testable relations for
b-baryon weak decays into a pentaquark and a light pseudoscalar. These
relations can be used as tests for the diquark model for pentaquark.Comment: revtex, 19 pages, 3 figures. one reference added and some typos
correcte
Search for a heavy dark photon at future colliders
A coupling of a dark photon from a with the standard model
(SM) particles can be generated through kinetic mixing represented by a
parameter . A non-zero also induces a mixing between
and if dark photon mass is not zero. This mixing can be large when
is close to even if the parameter is small. Many
efforts have been made to constrain the parameter for a low dark
photon mass compared with the boson mass . We study the
search for dark photon in for a
dark photon mass as large as kinematically allowed at future
colliders. For large , care should be taken to properly treat possible
large mixing between and . We obtain sensitivities to the parameter
for a wide range of dark photon mass at planed colliders,
such as Circular Electron Positron Collider (CEPC), International Linear
Collider (ILC) and Future Circular Collider (FCC-ee). For the dark photon mass
, the
exclusion limits on the mixing parameter are . The CEPC with and FCC-ee with
are more sensitive than the constraint from current
LHCb measurement once the dark photon mass . For , the sensitivity at
the FCC-ee with and is better
than that at the 13~TeV LHC with , while the sensitivity at
the CEPC with and can be even
better than that at 13~TeV LHC with for
.Comment: 21 pages, 5 figures, 2 table
- …