arXiv subjects

Mick Mulder

Publications and source records attributed to Mick Mulder.

4 recordsLinked to original sources

arXiv2026

Looking forward to $B^+\to \tau^+ \nu_\tau$ and $B_c^+\to \tau^+ \nu_\tau$

These proceedings present the outcome of a feasibility study using RapidSim simulation software that demonstrates that the LHCb experiment will be capable of observing the decays $B^+\to \tau^+ \nu_\tau$ and $B_c^+\to \tau^+ \nu_\tau$ using the data that is being collecting during Run 3 of the LHC. The proposed analysis exploits the small distance of only 5.1 millimetres between the sensing elements of LHCb's innermost silicon pixel detector, the VELO, and the LHC's proton beams to identify direct pixel hits in the VELO that can be associated with the charged $B^+$, $B_c^+$ or $\tau^+$ particles. By using this extra information, the limitations due to the missing momentum and vertex information will be significantly reduced. This provides enough statistical power to pursue the measurements of these two decay channels at the LHC. In particular for the decay $B_c^+\to \tau^+ \nu_\tau$, which has been identified by the high energy physics community as a key objective for experiments at the planned next-generation particle accelerators, this means we do not need to wait for the 2030s or beyond to get first experimental constraints.

hep-ex↗

arXiv2026

Tracking charged $b$-hadrons: feasibility study of the use of inner trackers to improve $B^{+}_{(c)}$ reconstruction

A method to improve the reconstruction of charged b-hadron decays is proposed that uses energy deposits left by the hadron in tracking detectors close to the production point. Performances are shown for different detector configurations and different number of deposits reconstructed, as obtained in simulation, for $b$-hadrons produced in high energy proton-proton collisions. It is shown that up to few percent of the $B^+$ mesons could leave two deposits before decaying, depending on the detector configuration. The presented results can inform the design of future inner detectors. This method could increase significantly the physics reach of flavour physics at hadron colliders, opening it to decays with missing particles and vertex information that are otherwise unreconstructable.

hep-ex↗

arXiv2017

The branching fraction and effective lifetime of $B_{(s)}^{0} \rightarrow \mu^+ \mu^-$ at LHCb with Run 1 and Run 2 data

After Run 1 of the LHC, global fits to $b \rightarrow s \ell \ell$ observables show a deviation from the Standard Model (SM) with a significance of $\sim$ 4 standard devations. An example of a $b \rightarrow s \ell \ell$ process is the decay of a $B_{s}^0$ meson into two muons ($B_{s}^0 \rightarrow \mu^+ \mu^-$). The latest analysis of $B_{(s)}^0 \rightarrow \mu^+ \mu^-$ decays by LHCb with Run 1 and Run 2 data is presented. The $B_{s}^0 \rightarrow \mu^+ \mu^-$ decay is observed for the first time by a single experiment. In addition, the first measurement of the $B_{s}^0 \rightarrow \mu^+ \mu^-$ effective lifetime is performed. No significant excess of $B^0 \rightarrow \mu^+ \mu^-$ decays is observed. All results are consistent with the SM and constrain New Physics in $b \rightarrow s \ell \ell$ processes.

hep-ex↗

arXiv2015

Anatomy of $B\rightarrow D\bar{D}$ Decays

The decays $B_d^0\rightarrow D_d^-D_d^+$ and $B_s^0\rightarrow D_s^-D_s^+$ probe the CP-violating mixing phases $\phi_d$ and $\phi_s$, respectively. The theoretical uncertainty of the corresponding determinations is limited by contributions from penguin topologies, which can be included with the help of the $U$-spin symmetry of the strong interaction. We analyse the currently available data for $B^0_{d,s}\rightarrow D_{d,s}^-D_{d,s}^+$ decays and those with similar dynamics to constrain the involved non-perturbative parameters. Using further information from semileptonic $B_d^0\rightarrow D_d^-\ell^+\nu_{\ell}$ decays, we perform a test of the factorisation approximation and take non-factorisable $SU(3)$-breaking corrections into account. The branching ratios of the $B_d^0\rightarrow D_d^-D_d^+$, $B_s^0\rightarrow D_s^-D_d^+$ and $B_s^0\rightarrow D_s^-D_s^+$, $B_d^0\rightarrow D_d^-D_s^+$ decays show an interesting pattern which can be accommodated through significantly enhanced exchange and penguin annihilation topologies. This feature is also supported by data for the $B_s^0\rightarrow D_d^-D_d^+$ channel. Moreover, there are indications of potentially enhanced penguin contributions in the $B_d^0\rightarrow D_d^-D_d^+$ and $B_s^0\rightarrow D_s^-D_s^+$ decays, which would make it mandatory to control these effects in the future measurements of $\phi_d$ and $\phi_s$. We discuss scenarios for high-precision measurements in the era of Belle II and the LHCb upgrade.

hep-ph↗