Narrow Results

We present a review of the operation and of the most recent results from the LHCb experiment at the LHC collider, based on the analyses performed using the data collected in 2010 and 2011, which correspond to an integrated luminosity of ~ 1 fb^-1. These measurements set stringent new limits on the contributions of New Physics processes in the field of rare b decays, and in the search for CP violation in B⁰ and mesons decays. In addition, a summary of results from studies of CP violation in the charm sector are presented, together with measurements in quarkonia production, in spectroscopy, in electroweak physics and in searches for exotica. The planned upgrade of LHCb is also briefly discussed.

In 2010, the CERN (European Centre for Particle Physics Research) Research Board unanimously approved MoEDAL, the seventh international experiment at the Large Hadron Collider (LHC), which is designed to search for avatars of new physics signified by highly ionizing particles. A MoEDAL discovery would have revolutionary implications for our understanding of the microcosm, providing insights into such fundamental questions as: do magnetic monopoles exist, are there extra dimensions or new symmetries of nature; what is the mechanism for the generation of mass; what is the nature of dark matter and how did the big bang unfurl at the earliest times.

We simulate proton–proton interactions to study densities and multiplicities of charged particles at center-of-mass energy, $\sqrt{s}=7$ TeV in the forward region and compare predictions with experimental findings of LHCb detector. We use different event generators: Sibyll2.3c, EPOS (1.99 and LHC tunes), and DPMJETIII for the simulations. The kinematic region for momentum $p>2\mathrm{\text{GeV}}/c$, transverse momentum $p_T>0.2\mathrm{\text{GeV}}/c$ and $2.0<\eta <4.8$ in pseudorapidity is kept same as in the LHCb experiment for forward region. Predictions of different models and experimental data are presented and compared as a function of transverse momentum and pseudorapidity.

The physics program of LHCb concerns the study of CP violation in the B system, including more precise determination of the CKM matrix parameters and in particular the determination of φ_s The search for new physics which could manifest itself indirectly will be a high priority. The main advantages of LHCb over the B factories are the access to the B_s system and very large B production rates. In addition, LHCb is a dedicated B physics experiment with excellent vertexing and particle identification capabilities. It is currently setting up its detector in its allocated LHC interaction region and is foreseen to be ready for data taking in November 2007 for the pilot run.

LHCb is a dedicated detector for b physics at the LHC (Large Hadron Collider). In this paper we present a concise review of the detector design and performance together with the main physics goals and their relevance for a precise test of the Standard Model and search of New Physics beyond it.

We present recent results from charmonium and open charm production at the LHCb experiment at CERN, Geneva. We concentrate on studies for the measurement of the cross section pp → J/ψX in its decay channel with two muons, showing the agreement of the simulation with the data in few key distributions. We also show the reconstructed modes of D⁰ → K^-π⁺, D⁰ → K^-π⁺π⁰, and and their prospects.

The recent and ongoing studies in quarkonium physics at LHCb are reviewed and future prospects are given in the field of quarkonium physics.

In experiments at the luminosity frontier, New Physics is being searched for in precision studies of rare processes. The most important example of such an effort is experiments at B factories and super B factories. While B factories have fully established the CKM quark transition matrix as the only source of CP violation in the Standard Model, the next generation of B factories, the so-called super B factories, will look for departures from the Standard Model. To collect a 50 times larger data sample, needed to reach the required sensitivity, a substantial B factory upgrade is being carried out. The SuperKEKB accelerator complex is designed for an increase in luminosity by a factor of 40. The upgraded Belle II spectrometer is being constructed to operate at considerably higher event rates, as well as higher backgrounds, accompanied by an increase in occupancy and radiation damage. Higher event rates also require substantial modifications in the trigger scheme, data acquisition system and computing. The paper discusses the detectors at B factories, the motivation for SuperKEKB/Belle II, the super B factory at KEK, as well as the requirements for the new accelerator and for the new detector. The present status of the project will be presented together with plans for the future. We will also discuss its competition, the LHCb experiment at the LHC.

In this paper, we present a review of forward physics measurements performed with LHC Runs 1 and 2 data. In particular, measurements based on proton–proton collisions with different center-of-mass energies (0.9–13 TeV) are reviewed. We focus on measurements exploring the forward phase space using the available instrumentation at the different LHC experiments, and report on forward jet and forward energy flow measurements.

While the LHCb detector was specifically designed for measuring heavy-flavor physics, it has also proven itself as a forward general purpose detector with flexible data acquisition, excellent lifetime resolution and charged particle identification. This makes LHCb an ideal laboratory for exploring phenomena related to quantum chromodynamics (QCD), particularly with heavy-flavor content. This review explores some of the novel QCD measurements from LHCb, with an emphasis placed on comparisons to predictions from the Pythia 8 Monte Carlo event generator.

Here, we report on the results and prospects of the LHCb experiment at CERN as well as the upgrades of the LHCb detector within the scope of heavy-ion physics. A particular attention will be given to the extension of the fixed-target program and to the performance of the detector in high-occupancy nucleus–nucleus collisions. The technical description will be followed by a discussion of the results and the prospects for heavy-ion physics in fixed-target and collider mode.

Recent results on mixing, CP violation and rare decays in charm physics from the LHCb experiment are presented. Study of "wrong-sign" D⁰ → K⁺π^- decays provides the highest precision measurements to date of the mixing parameters x′² and y′, and of CP violation in this decay mode. Direct and indirect CP violation in the D⁰ system are probed to a sensitivity of around 10^-3 using D⁰ → K⁺K⁻ and D⁰ → π⁺π⁻ decays and found to be consistent with zero. Searches for the rare decays , and D⁰ → μ⁺μ⁻ find no evidence of signal, but set the best limits on branching fractions to date. Thus, despite many excellent results in charm physics from LHCb, no evidence for physics beyond the Standard Model is found.

The rich proton-proton collision data of the LHC allow the study of QCD processes in a previously unexplored region with ever improving precision. This paper summarises recent results of the ATLAS, CMS and LHCb Collaborations using primarily multi-jet and vector boson plus jet data collected at $\sqrt{s}=8$ and 13 TeV. Comparisons to higher-order theoretical calculations and sophisticated Monte Carlo predictions are presented, as well as the impact of the data on the determination of the parton distribution functions and the measurement of the strong coupling constant, α_s.

The LHCspin project aims to bring polarized physics at the LHC through the installation of a gaseous fixed target at the upstream end of the LHCb detector. The forward geometry of the LHCb spectrometer (2 < η < 5) is perfectly suited for the reconstruction of particles produced in fixed-target collisions. The fixed-target configuration, with center-of-mass energy at $\sqrt{s}=115\text{GeV}$, allows to cover a wide backward center-of-mass rapidity region, corresponding to the poorly explored high x-Bjorken and high x-Feynman regimes. The project has several ambitious goals, in particular regarding nucleon’s internal dynamics in terms of both quarks and gluons degrees of freedom. The use of transversely polarized H and D targets will allow to study the quarks TMDs in pp collisions at unique kinematic conditions.

The charm sector is an unique probe to possible new physics coupling to up-type quarks and offers a complimentary approach to direct searches for particles originating from processes not described by the Standard Model of Particle physics (SM). Contributions beyond the SM could originate from the higher-order loop effects and assuming generic beyond SM scenarios, much higher mass scales are accessible in comparison with direct searches. Measurements of Charge-Parity (CP) violation and mixing in charm decays are promising method to probe the aforementioned effects. The violation of CP symmetry in charm was observed for the first time by the LHCb experiment in 2019.

These proceedings present a measurement of the mass difference between neutral charm meson mass eigenstates, a search for time-dependent CP violation in neutral charm meson decays and the first observation of CP violation in charm hadrons decays.

The LHCb Experiment is going to search for the contribution of New Physics by studying large statistics samples of b-hadron decays. The key components of the experimental setup are discussed, followed by the overall status of the detector construction. The expected sensitivity is given for a few key channels.

Pion/kaon discrimination in the LHCb experiment will be provided by two Ring Imaging Cherenkov (RICH) counters. These use arrays of 484 Hybrid Photon Detectors (HPDs) to detect the Cherenkov photons emitted by charged particles traversing the RICH. The results from comprehensive quality assurance tests on the 550 HPDs manufactured for LHCb are described. Leakage currents, dead channel probabilities, dark count rates and ion feedback rates are reported. Furthermore, measurements carried out on a sample of tubes to determine the efficiency of the HPD pixel chip by measuring the summed analogue response from the backplane of the silicon sensor are described.

The production of Hybrid Photon Detectors to be used as the single-photon sensors for the RICH detectors of the LHCb experiment has recently finished. We present the quantum efficiency measurements of the entire sample of 550 tubes. The manufacturer has succeeded in consistently improving the quantum efficiency of the employed S20-type multi-alkali photocathode above our expectations, by a relative 27 % integrated over the energy spectrum. We also report measurements of the vacuum quality using the photocurrent of the device as a monitor for possible vacuum degradation.

As the completion of the LHCb detector approaches we report on the status of the Ring Imaging Cherenkov (RICH) detectors that provide light hadron particle identification. The design and status of the two detectors RICH1 and RICH2 is explored and an overview is given of the photon detector technology the Hybrid Photon Detector. RICH1 is a more compact system working at lower particle momenta closer to the interaction point and is currently nearing completion. RICH2 is a larger detector operating at higher momenta and is complete and currently being commissioned.

The LHCb experiment will perform high-precision measurements of CP violation parameters and rare phenomena in B meson decays. It requires an excellent track reconstruction efficiency, particle identification and the precise measurement of secondary vertex positions in LHC collisions. We will discuss the methodology for the global reconstruction of tracks, using the ensemble of tracking detectors arranged on both sides of the LHCb dipole magnet. Hardware features of the tracking detectors that affect the tracking strategy will be outlined. We will describe the design and performance of the track reconstruction algorithms.