Physics case for an LHCb Upgrade II - Opportunities in flavour physics, and beyond, in the HL-LHC era

The LHCb Upgrade II will fully exploit the flavour-physics opportunities of the HL-LHC, and study additional physics topics that take advantage of the forward acceptance of the LHCb spectrometer. The LHCb Upgrade I will begin operation in 2020. Consolidation will occur, and modest enhancements of the Upgrade I detector will be installed, in Long Shutdown 3 of the LHC (2025) and these are discussed here. The main Upgrade II detector will be installed in long shutdown 4 of the LHC (2030) and will build on the strengths of the current LHCb experiment and the Upgrade I. It will operate at a luminosity up to 2×1034 cm−2s−1, ten times that of the Upgrade I detector. New detector components will improve the intrinsic performance of the experiment in certain key areas. An Expression Of Interest proposing Upgrade II was submitted in February 2017. The physics case for the Upgrade II is presented here in more depth. CP-violating phases will be measured with precisions unattainable at any other envisaged facility. The experiment will probe b → sl+l−and b → dl+l− transitions in both muon and electron decays in modes not accessible at Upgrade I. Minimal flavour violation will be tested with a precision measurement of the ratio of B(B0 → μ+μ−)/B(Bs → μ+μ−). Probing charm CP violation at the 10−5 level may result in its long sought discovery. Major advances in hadron spectroscopy will be possible, which will be powerful probes of low energy QCD. Upgrade II potentially will have the highest sensitivity of all the LHC experiments on the Higgs to charm-quark couplings. Generically, the new physics mass scale probed, for fixed couplings, will almost double compared with the pre-HL-LHC era; this extended reach for flavour physics is similar to that which would be achieved by the HE-LHC proposal for the energy frontier

LHCb upgrade software and computing : technical design report

This document reports the Research and Development activities that are carried out in the software and computing domains in view of the upgrade of the LHCb experiment. The implementation of a full software trigger implies major changes in the core software framework, in the event data model, and in the reconstruction algorithms. The increase of the data volumes for both real and simulated datasets requires a corresponding scaling of the distributed computing infrastructure. An implementation plan in both domains is presented, together with a risk assessment analysis

Syntheses of Heteroleptic Amidinate Strontium Complexes Using a Superbulky Ligand

Strontium complexes are presented with two different bulky amidinate ligands (Am): <i>t</i>BuC­(N<i>-</i>DIPP)₂ (DIPP = 2,6-diisopropylphenyl), abbreviated here as <i>t</i>BuAm^DIPP, and (<i>p</i>-tolyl)­C­(N-Ar^‡)₂ (Ar^‡ = 2,6-Ph₂CH-4-<i>i</i>Pr-phenyl) abbreviated here as <i>p</i>TolAm^Ar‡. The amidine <i>t</i>BuAm^DIPP-H was deprotonated by Sr­[N­(SiMe₃)₂]₂ in benzene at 60 °C. Although the product, <i>t</i>BuAm^DIPPSrN­(SiMe₃)₂, could be characterized by NMR, attempts to isolate it led to ligand scrambling via a Schlenk equilibrium. Reaction of in situ prepared <i>t</i>BuAm^DIPPSrN­(SiMe₃)₂ with PhSiH₃ gave PhH₂SiN­(SiMe₃)₂ and presumably the intermediate <i>t</i>BuAm^DIPPSrH, but the latter is not stable and the homoleptic complex (<i>t</i>BuAm^DIPP)₂Sr was isolated and structurally characterized. Deprotonation of the bulkier amidine <i>p</i>TolAm^Ar‡-H with Sr­[N­(SiMe₃)₂]₂ needed forcing conditions, inevitably giving rise to deprotonation of the Ph₂CH substituent as well. Reaction of <i>p</i>TolAm^Ar‡-H with the less bulky and less basic Sr­[N­(SiHMe₂)₂]₂, however, gave the heteroleptic product <i>p</i>TolAm^Ar‡SrN­(SiHMe₂)₂, which has been structurally characterized. The latter was also at 60 °C stable toward ligand scrambling. Reaction with PhSiH₃ did give hydride exchange, but the product <i>p</i>TolAm^Ar‡SrH decomposed even at −30 °C. Instead, an amidinate complex with a deprotonated Ph₂CH substituent was isolated and structurally characterized (<b>7</b>). The latter catalyzed the intramolecular alkene hydroamination

Reactions of [RuCl₂(PPh₃)₃] with Nitron and with the “Enders Carbene”: Access to Ruthenium(III) NHC Complexes

The reactions of [RuCl₂(PPh₃)₃] with the “Enders carbene” 1,3,4-triphenyl-1,2,4-triazol-5-ylidene (<b>1</b>) and the “instant carbene” Nitron (<b>2</b>) respectively afforded the Ru^II chelates [RuCl­(<b>3</b>)­(PPh₃)₂] (<b>3</b> = 3,4-diphenyl-1-<i>o</i>-phenylene-1,2,4-triazol-5-ylidene) and [RuCl­(<b>4</b>)­(PPh₃)₂] (<b>4</b> = 4-phenyl-3-phenylamino-1-<i>o</i>-phenylene-1,2,4-triazol-5-ylidene) in a process involving the ortho metalation of the 1-Ph group of the respective carbene ligand. It proved possible to synthesize [RuCl­(<b>3</b>)­(PPh₃)₂] more conveniently in higher yield by using the stable carbene precursor 5-methoxy-1,3,4-triphenyl-4,5-dihydro-1<i>H</i>-1,2,4-triazole (MeO-<b>1</b>-H) instead of the free carbene <b>1</b> in the presence of triethylamine to trap the HCl generated by the ortho metalation. Aerobic oxidation of the Ru^II chelates in the presence of chloride ions furnished [RuCl₂(<b>3</b>)­(PPh₃)₂] and [RuCl₂(<b>4</b>)­(PPh₃)₂], which are rare examples of Ru^III NHC complexes. The crystal structures of all four complexes were determined by single-crystal X-ray diffraction studies. In addition, the crystal structure of the hydrochloride of Nitron was also determined. In the Ru^II chelates, the pentacoordinate metal center is in a distorted-square-pyramidal environment with the carbon atom of the ortho-metalated 1-Ph group occupying the apical position. The coordination sphere of the Ru^III chelates is complemented by a second chlorido ligand, which is positioned <i>trans</i> to this carbon atom

Stabilization of Calcium Hydride Complexes by Fine Tuning of Amidinate Ligands

A range of symmetric amidinate ligands RAm^Ar (R is backbone substituent, Ar is N substituent) have been investigated for their ability to stabilize calcium hydride complexes of the type RAm^ArCaH. It was found that the precursors of the type RAm^ArCaN­(SiMe₃)₂ are only stable toward ligand exchange for Ar = DIPP (2,6-diisopropylphenyl). The size of the backbone substituent R determines aggregation and solvation. The following complexes could be obtained: [RAm^DIPPCaN­(SiMe₃)₂]₂ (R = Me, <i>p</i>-Tol), RAm^DIPPCaN­(SiMe₃)₂·Et₂O (R = Np, <i>t</i>Bu), AdAm^DIPPCaN­(SiMe₃)₂·THF, and AdAm^DIPPCaN­(SiMe₃)₂. Reaction of these heteroleptic calcium amide complexes with PhSiH₃ gave only for larger backbone substituents (R = <i>t</i>Bu, Ad) access to the dimeric calcium hydride complexes (RAm^ArCaH)₂. (N,aryl)-coordination of the amidinate ligand seems crucial for the stability of these complexes, and the aryl···Ca interaction is found to be strong (17 kcal/mol). Addition of polar solvents led to a new type of trimeric calcium hydride complex exemplified by the crystal structures of (<i>t</i>BuAm^DIPPCaH)₃·2Et₂O and (AdAm^DIPPCaH)₃·2THF. The overall conclusion of this work is that minor changes in sterics (<i>t</i>Bu vs Ad) or coordinated solvent (THF vs Et₂O) can have large consequences for product formation and stability

Observation of B(s)0→J/ψpp‾B^0_{(s)} \to J/\psi p \overline{p} decays and precision measurements of the B(s)0B^0_{(s)} masses

International audienceThe first observation of the decays B(s)0→J/ψpp¯ is reported, using proton-proton collision data corresponding to an integrated luminosity of 5.2  fb-1, collected with the LHCb detector. These decays are suppressed due to limited available phase space, as well as due to Okubo-Zweig-Iizuka or Cabibbo suppression. The measured branching fractions are B(B0→J/ψpp¯)=[4.51±0.40(stat)±0.44(syst)]×10-7, B(Bs0→J/ψpp¯)=[3.58±0.19(stat)±0.39(syst)]×10-6. For the Bs0 meson, the result is much higher than the expected value of O(10-9). The small available phase space in these decays also allows for the most precise single measurement of both the B0 mass as 5279.74±0.30(stat)±0.10(syst)  MeV and the Bs0 mass as 5366.85±0.19(stat)±0.13(syst)  MeV