Model-independent measurement of mixing parameters in D0^{0} → KS0_{S}^{0} π+^{+}π−^{−} decays

The first model-independent measurement of the charm mixing parameters in the decay $D^0 \to K_S \pi^+ \pi^-$ is reported, using a sample of $pp$ collision data recorded by the LHCb experiment, corresponding to an integrated luminosity of 1.0 fb$^{-1}$ at a centre-of-mass energy of 7 TeV. The measured values are \begin{eqnarray*} x &=& (-0.86 \pm 0.53 \pm 0.17) \times 10^{-2}, \\ y &=& (+0.03 \pm 0.46 \pm 0.13) \times 10^{-2}, \end{eqnarray*} where the first uncertainties are statistical and include small contributions due to the external input for the strong phase measured by the CLEO collaboration, and the second uncertainties are systematic.Comment: 25 pages, 3 figures. Sign error in x fixed as of v2. All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-042.htm

Muon Collider Forum Report

A multi-TeV muon collider offers a spectacular opportunity in the direct exploration of the energy frontier. Offering a combination of unprecedented energy collisions in a comparatively clean leptonic environment, a high energy muon collider has the unique potential to provide both precision measurements and the highest energy reach in one machine that cannot be paralleled by any currently available technology. The topic generated a lot of excitement in Snowmass meetings and continues to attract a large number of supporters, including many from the early career community. In light of this very strong interest within the US particle physics community, Snowmass Energy, Theory and Accelerator Frontiers created a cross-frontier Muon Collider Forum in November of 2020. The Forum has been meeting on a monthly basis and organized several topical workshops dedicated to physics, accelerator technology, and detector R&D. Findings of the Forum are summarized in this report

TF07 Snowmass Report: Theory of Collider Phenomena

11+11 pages, 343 contributors, 1 key formula; contribution to Snowmass 2021, draft report of the Theory Frontier topical group for Collider Phenomenology (TF07), comments and suggestions welcome ; v2: updated contributor listTheoretical research has long played an essential role in interpreting data from high-energy particle colliders and motivating new accelerators to advance the energy and precision frontiers. Collider phenomenology is an essential interface between theoretical models and experimental observations, since theoretical studies inspire experimental analyses while experimental results sharpen theoretical ideas. This report -- from the Snowmass 2021 Theory Frontier topical group for Collider Phenomenology (TF07) -- showcases the dynamism, engagement, and motivations of collider phenomenologists by exposing selected exciting new directions and establishing key connections between cutting-edge theoretical advances and current and future experimental opportunities. By investing in collider phenomenology, the high-energy physics community can help ensure that theoretical advances are translated into concrete tools that enable and enhance current and future experiments, and in turn, experimental results feed into a more complete theoretical understanding and motivate new questions and explorations

Determination of the quark coupling strength vertical bar V-ub vertical bar using baryonic decays

In the Standard Model of particle physics, the strength of the couplings of the b quark to the u and c quarks, vertical bar V-ub vertical bar and vertical bar V-ub vertical bar, are governed by the coupling of the quarks to the Higgs boson. Using data from the LHCb experiment at the Large Hadron Collider, the probability for the Lambda(0)(b) baryon to decay into the p mu(-)(nu) over bar (mu) final state relative to the Lambda(+)(c)mu(-)(nu) over bar (mu) final state is measured. Combined with theoretical calculations of the strong interaction and a previously measured value of vertical bar V-ub vertical bar, the first vertical bar V-ub vertical bar measurement to use a baryonic decay is performed. This measurement is consistent with previous determinations of vertical bar V-ub vertical bar using B meson decays to specific final states and confirms the existing incompatibility with those using an inclusive sample of final states

Measurement of psi (2S) production cross-sections in proton-proton collisions at v s=7 and 13 TeV

The cross-sections of \u3c8(2 S) meson production in proton-proton collisions at s=13TeV are measured with a data sample collected by the LHCb detector corresponding to an integrated luminosity of 275pb-1. The production cross-sections for prompt \u3c8(2 S) mesons and those for \u3c8(2 S) mesons from b-hadron decays (\u3c8(2S)-from-b) are determined as functions of the transverse momentum, pT, and the rapidity, y, of the \u3c8(2 S) meson in the kinematic range 2<20GeV/c and 2.0 < y< 4.5. The production cross-sections integrated over this kinematic region are \u3c3(prompt\u3c8(2S),13TeV)=1.430\ub10.005(stat)\ub10.099(syst)\u3bcb,\u3c3(\u3c8(2S)-from-b,13TeV)=0.426\ub10.002(stat)\ub10.030(syst)\u3bcb.A new measurement of \u3c8(2 S) production cross-sections in pp collisions at s=7TeV is also performed using data collected in 2011, corresponding to an integrated luminosity of 614pb-1. The integrated production cross-sections in the kinematic range 3.5<14GeV/c and 2.0 < y< 4.5 are \u3c3(prompt\u3c8(2S),7TeV)=0.471\ub10.001(stat)\ub10.025(syst)\u3bcb,\u3c3(\u3c8(2S)-from-b,7TeV)=0.126\ub10.001(stat)\ub10.008(syst)\u3bcb.All results show reasonable agreement with theoretical calculations

Measurement of the eta(c)(1S) production cross-section in p p collisions at root s=13TeV

Using a data sample corresponding to an integrated luminosity of 2.0 fb-1, collected by the LHCb experiment, the production of the \u3b7c(1 S) state in proton\u2013proton collisions at a centre-of-mass energy of s=13TeV is studied in the rapidity range 2.0 < y< 4.5 and in the transverse momentum range 6.5<14.0GeV. The cross-section for prompt production of \u3b7c(1 S) mesons relative to that of the J/ \u3c8 meson is measured using the pp\uaf decay mode and is found to be \u3c3\u3b7c(1S)/\u3c3J/\u3c8=1.69\ub10.15\ub10.10\ub10.18. The quoted uncertainties are, in order, statistical, systematic and due to uncertainties on the branching fractions of the J/\u3c8\u2192pp\uaf and \u3b7c\u2192pp\uaf decays. The prompt \u3b7c(1 S) production cross-section is determined to be \u3c3\u3b7c(1S)=1.26\ub10.11\ub10.08\ub10.14\u3bcb, where the last uncertainty includes that on the J/ \u3c8 meson cross-section. The ratio of the branching fractions of b-hadron decays to the \u3b7c(1 S) and J/ \u3c8 states is measured to be Bb\u2192\u3b7cX/Bb\u2192J/\u3c8X=0.48\ub10.03\ub10.03\ub10.05, where the last uncertainty is due to those on the branching fractions of the J/\u3c8\u2192pp\uaf and \u3b7c\u2192pp\uaf decays. The difference between the J/ \u3c8 and \u3b7c(1 S) masses is also determined to be 113.0\ub10.7\ub10.1MeV, which is the most precise single measurement of this quantity to date