A Possibility of Search for New Physics at LHCb

It is interesting to search for new physics beyond the standard model at LHCb. We suggest that weak decays of double-charmed baryon such as $\Xi_{cc}(3520)^+, \Xi_{cc}^{++}$ to charmless final states would be a possible signal for new physics. In this work, we consider two models, i.e. the unparticle and $Z'$ as examples to study such possibilities. We also discuss the case for $\Xi^0_{bb}, \Xi_{bb}^-$ which has not been observed yet, but will be available as LHCb begins running. Our numerical results show that these two models which are becoming more popular nowadays cannot result in sufficiently large decay widths, therefore if such modes are observed at LHCb, there must be a new physics model other than the unparticle or $Z'$.