A time dependent angular analysis of the decay mode $B_s \rightarrow J/ψϕ$ allows for the measurement of the mixing induced CP-violating phase $ϕ_s$. Within the Standard Model $ϕ_s$ is theoretically precisely predicted to be very small, however many Standard Model extensions predict sizeable contributions to this phase. The current experimental knowledge of $ϕ_s$ has very larger uncertainties. However already with the data expected to be delivered within the next year, the LHCb experiment at the Large Hadron Collider at CERN, has the potential to improve significantly existing measurements. In a data set of up to 37.5 pb$^{-1}$ taken in 2010, first physics signals in the LHCb detector are reconstructed and their properties are compared to Monte Carlo predictions. Based on recently published measurements of $b\bar{b}$ cross-sections from the LHCb collaboration, the sensitivity on the $CP$ violating phase $ϕ_s$ in the decay $B_s \rightarrow J/ψϕ$ is evaluated. Additionally an alternative method to potentially extract complementary information on $ϕ_s$ from the measurement of the asymmetry in semileptonic final states is presented.
The LHCb experiment will search for New Physics in Bs mixing. The Bs mixing phase will be extracted from the measurement of the time-dependent CP asymmetry in exclusive Bs decays governed by the b -> ccbar s quark-level transition. Large New Physics effects can be discovered or excluded with the data collected during the very first physics run of LHC. Based on Monte Carlo simulations of the LHCb detector, the expected sensitivity with 2 inverse fb on the CP-violation parameter phi_s is sigma(phi_s) = 0.022.
The LHCb experiment will operate for about five years at a luminosity of 2x10^32 cm^-2 s^-1 and plans are to accumulate a data sample of ~10 fb^-1. Here we present the physics programme and detector design for a future high luminosity phase of the LHCb experiment. An upgraded LHCb experiment would operate at ten times the design luminosity, i.e. at ~2x10^33 cm^-2 s^-1 and aims to collect a data sample of ~100 fb^-1 over five years. This programme would allow the probe of new physics at an unprecedented level. Key measurements include the B^0_s mixing phase phi_s in B^0_s -> J/ψphi and B^0_s ->…
The interference between Bs decay amplitudes to CP eigenstates Jpsi X directly or including Bs-Bsbar oscillation gives rise to a measurable CP violating phase phi_s. Here, a preliminary measurement of phi_s with Bs -> JpsiK+K- decays, and the measurement using Bs->Jpsipi+pi- decays, both obtained from a sample of 1/fb of pp collisions, collected by the LHCb experiment at a centre-of-mass energy sqrt{s}=7 TeV during 2011, are presented. In addition, the determination of the branching fraction and polarization fractions of Bs->JpsiKstbar, which can be used to constrain the contribution of sub-le…
Using 1fb^{-1} of pp collision data collected at center of mass energy sqrt{s} = 7 TeV during 2011 by the LHCb detector. Measurements of the triple product asymmetries, polarisation amplitudes and strong phase difference in the decay B_s^0 to phi phi are presented.
These proceedings present the current status of measurements of the CP-violating phase $phi_s$ by the LHCb collaboration, reviewing the measurements in channels such as $B_s^0\to J/ψϕ$, $B_s^0\to J/ψπ^+π^-$ and $B_s^0 \to ψ(2S)ϕ$. The observation of the $B_s^0\toη_cϕ$ decay mode is presented for the first time, which can be used to measure $ϕ_s$ with larger data samples that will be collected over the coming years by the LHCb experiment. Finally, the expected increase in precision from LHCb measurements of $ϕ_s$ over the next decade is presented.
Measurement of the CKM phase gamma in B->DK decays can be potentially performed with high precision due to low theoretical uncertainties. However, the precision measurement requires very large experimental samples of B decays. This report covers prospects for gamma measurement at the future e+e- facilities and upgraded LHCb detector.
The hadronic decay D0 -> KS0 pi+ pi- provides access to the measurement of the mixing parameters of the neutral D-meson system and allows to test for CP violation. A measurement of the mixing parameters x_D and y_D as well as of the parameters |q/p| and phi=arg(q,p), which govern indirect CP violation, will be performed based on a time-dependent amplitude-model analysis of the full LHCb dataset of 2011 and 2012 corresponding to an integrated luminosity of 3/fb.
Heavy flavor productions are important tests of QCD. In proton-proton collisions collected at LHCb, a long list of measurements for charm and bottom productions have been made. This talk focuses on the studies of fragmentation functions and production asymmetries for bottom hadrons. They provide inputs for absolute branching fraction measurements and CP violation studies at LHCb respectively.
The LHCb experiment collected during run I the world's largest sample of charmed hadrons. This sample is used to search for CP violation in charm and for the measurements of D0 mixing parameters. The measurement of the D0 to D0bar mixing parameters and the search for indirect CP-violation in two-body charm decays at LHCb experiment are presented.
LHCb presents studies of particle production in minimum bias events in pp collisions at \sqrt{s} = 7 TeV. These studies include measurements of strangeness production, particle ratios, baryon-antibaryon ratios and charged particle production. The forward coverage and low pT acceptance of the experiment makes these measurements very complementary to those performed by the central detectors at the LHC. Further benefits arise from the powerful particle identification capabilities provided by the LHCb RICH system. The measurements are compared with theoretical predictions.
The LHCb experiment, bolstered up by the 10^12 b-hadrons to be produced yearly in its interaction region, is an excellent place to study rare B decays. Flavor-changing neutral currents are forbidden at tree level in the Standard Model. They proceed through loop diagrams and hence are indirectly sensitive to New Physics through the effect of new particles on observable quantities. In this paper, we present preparation studies of the three most promising B rare decay analyzes. These aim at the observation of the photon polarization in B_s to phi gamma, the measurement of the angular distribution…
Decays of b-hadrons are the ideal place to perform measurements of CP violation. Many decay channels allow to over-constrain the unitarity triangles of the CKM matrix and test the SM hypothesis that a single phase is the origin of all CP violation. Charm decays also allow for tests of the SM. Recent results from LHCb are reviewed.
Precision measurements of b-hadron lifetimes are a key goal of the LHCb experiment. In the B_s sector, the measurement of the effective lifetimes for B_s mesons decaying to CP-odd, CP-even and flavor specific final states are essential for constraining the B_s mixing parameters, $ΔΓ_s$, the average width, $Γ_s$, and the CP-violating phase, $ϕ_s$. Measurements of $b$ baryon lifetimes are also important to test theoretical models. We present the latest results from LHCb on these topics.
The LHCb experiment covers a unique region of acceptance at forward rapidities in the high energy proton-proton collisions of the LHC. This means that measurements of particle production in LHCb are directly sensitive to the parton distribution functions at low Björken-$x$ values. Several measurements of inclusive $W$ and $Z/γ^{\ast}$ production with the Run-I dataset are reported in these proceedings. Further measurements of $W$ and $Z/γ^{\ast}$ production in association with inclusive jets and $b$- and $c$-tagged jets are also reported.
The status and prospects of time-integrated measurements of the CKM angle gamma at LHCb, the LHC's dedicated flavor physics experiment, are reviewed. Yields obtained from early data taking are presented and extrapolations are made to estimate what can be expected to be obtained from the 2011 data. The conclusions drawn from these extrapolations are that LHCb will produce the world's best measurement of gamma by the end of 2011 and that the long-term outlook is excellent.
The measurement of the mixing-induced CP-violating phase $ϕ_s$ in the $B^0_s - \bar{B}^0_s$ system is one of the key goals of the LHCb experiment, and provides an excellent opportunity to search for New Physics beyond Standard Model. Using Run-I data, $ϕ_s$ has been measured in several decay channels. These proceedings briefly summarise the previous LHCb Run-I results of $ϕ_s$ measurement, and show the most recent results obtained by analysing the decay channel $B^0_s \to J/ψK^+ K^-$ in the $K^+ K^-$ mass region above the $ϕ$(1020) resonance.
LHCb is the dedicated B physics experiment at the LHC and is due to start data taking later this year. Its goal is to search for new physics in very rare processes and make precision measurements of CP violation in B decays. The CKM angle gamma plays an important role in flavour physics in the Standard Model. LHCb will exploit the large variety of B hadrons produced by the 14 TeV pp collisions, performing gamma measurements to the precision of a few degrees. Here, we will present a summary of the expected gamma sensitivities LHCb will reach during its first years of data taking, with contribut…
The LHCb experiment has been able to collect the largest sample ever produced of charm-hadron decays, performing a number of measurements of observables related to $C\!P$ violation in the charm sector. In this document, the most recent results from LHCb on the search of direct $C\!P$ violation in $D^0 \to K_s^0 K_s^0$, $D_{(s)}^+ \to h^+ π^0$ and $D_{(s)}^+ \to h^+ η$ decays are summarised, in addition to the most precise measurement of time-dependent $C\!P$ asymmetry in $D^0 \to h^+ h^-$ decays and the first observation of mass difference between neutral charm-meson eigenstates.
Studies in the forward region of charged particle multiplicity and density, as well as energy flow, are presented. These measurements are performed using data from proton-proton collisions at a center-of-mass energy of 7 TeV, collected with the LHCb detector. The results are compared to predictions from a variety of Monte Carlo event generators and are used to test underlying event and hadronization models as well as the performance of event generator tunes in the forward region.
LHCb has recorded large samples of semileptonic {\textit B} decays. These provide the possibility to study {\textit CP} violation effects in the $B^{0}_s$ and $B^{0}$ systems. Decay-time-integrated or decay-time-dependent asymmetries between charge conjugated final states probe {\textit CP} violation in $B^{0}_{(s)}$ mixing through the measurement of the parameter $a_{\textrm sl}. These measurements rely on data-driven techniques to control possible detection asymmetries.
We present measurements of the oscillation frequencies $Δm_d$ and $Δm_s$ of $B$ meson mixing as well as a measurement of the time-dependent CP-asymmetry in decays of $B^0\to J/ψK_{\text{S}}^0$ based on $1.0\,\text{fb}^{-1}$ of data collected by the LHCb experiment in 2011. These measurements give valuable input to tests of the unitarity of the Cabibbo-Kobayashi-Maskawa matrix.
We present the results on the energy flow measured with minimum-bias data collected by the LHCb experiment in pp collisions at sqrt{s}=7 TeV for inclusive minimum-bias interactions, hard scattering processes and events with enhanced or suppressed diffractive contribution. The measurements are performed in the pseudorapidity range 1.9<η<4.9, which corresponds to the main detector acceptance of the LHCb spectrometer. The data are compared to predictions given by the PYTHIA-based and cosmic-ray Monte Carlo event generators, which model the underlying event activity in different ways.
We review the first measurements of the CKM angle gamma from LHCb. These measurements have been performed with b-hadron decays dominated by b -> u and b -> c tree-level amplitudes, from which gamma can be determined without theoretical uncertainties. Precision is achieved by averaging results from B- -> Dh- (h= K,pi) decays with D -> h+h-, D -> K+pi-, and D -> K+pi-pi+pi-, and D -> K_S^0h+h-. Prospects for these and future measurements of gamma using neutral b-hadron decays are briefly discussed.
Precision lifetime measurements of $b$-flavoured hadrons are an important test of the validity of the theoretical tool used to determine $b$-hadrons observables, the Heavy Quark Expansion. Recent measurements of the $B^+$, $Λ^0_b$, $Ξ^-_b$, $Ξ^0_b$ and $Ω^-_b$ hadrons lifetimes are reported. Moreover, several $B^0$ and $B^0_s$ effective lifetime measurements are discussed, as well as a measurement of the decay width difference in the $B^0$ system, $ΔΓ_d$. All the measurements have been performed using $pp$ collision data collected with the LHCb detector.
Determination of the mixing-induced $C\!P$-violating phase $ϕ_{s}$ and decay width difference $ΔΓ_{s}$ in $\bar{b}\to\bar{c}c\bar{s}$ decays is one of the main goals of the LHCb experiment. Thanks to the precise prediction of the $ϕ_{s}$ value within the Standard Model, it represents an excellent probe to search for new physics. The measurements of $ϕ_{s}$ and $ΔΓ_{s}$ at LHCb are reviewed including results from the 3.0~fb$^{-1}$ dataset accumulated during 2011-2012. Further measurement improvement is expected from the inclusion of results obtained using decay modes with smaller branching frac…
The LHCb experiment is one of four major experiments at the LHC. Despite being designed for the study of beauty and charm particles, it has made important contributions in other areas, such as the production and decay of $W$ and $Z$ bosons. Such measurements can be used to study and constrain parton distribution functions, as well as to test perturbative quantum chromodynamics in hard scattering processes. The angular structure of $Z$ boson decays to leptons can also be studied and used to measure the weak mixing angle. The phase space probed by LHCb is particularly sensitive to this quantity,…
An overview of plans for the measurement of gamma at the LHCb experiment will be shown. The gamma angle is the least accurately known parameter of the CKM unitary triangle. The LHCb experiment at the CERN LHC aims to perform precision heavy flavour and CP violation measurements, including improving the knowledge of gamma. Focus will be put on methods using B meson decays at the tree level, within the Standard Model framework. The early data recorded by the experiment, from pp collisions at sqrt{s} = 7 TeV, allowed observations of the first signals of the B decay modes that will be used to perf…
The LHCb experiment has the unique possibility, among the LHC experiments, to be operated in fixed target mode, using its internal gas target. The energy scale achievable at the LHC, combined with the LHCb forward geometry and detector capabilities, allow to explore particle production in a wide Bjorken-$x$ range at the $\sqrt{s_{\scriptscriptstyle\rm NN}} \sim 100$ GeV energy scale, providing novel inputs to nuclear and cosmic ray physics. The first measurement of antiproton production in collisions of LHC protons on helium nuclei at rest is presented. The knowledge of this cross-section is o…
During run I, the LHCb experiment at the LHC, CERN, collected 1.0 fb$^{-1}$ of pp collisions at $\sqrt{s} = 7$ TeV and 2.0 fb$^{-1}$ at $\sqrt{s} = 8$ TeV, yielding the world's largest sample of decays of charmed hadrons. This sample is used to search for direct and indirect CP violation in charm and to measure $D^{0}$ mixing parameters. Recent measurements from several complementary decay modes are presented.
The study of CP violation in \Bs\, oscillations is a key measurement at the LHCb experiment. In this document, we discuss the latest LHCb results on the CP-violating phase, called $ϕ_s$, using \BsJKK\, and \BsJpipi\, channels. To conclude on the presence of New Physics in $ϕ_s$, the estimation of the sub-dominant contributions from the Standard Model becomes crucial now. We outline a method to estimate the contribution of penguin diagrams in $ϕ_s$. Branching fractions and upper limits of \BdKshh\,($ h^{(')}=K,π)$\, modes are presented.
The study of CP violation in $B_s^0$ oscillations is one of the key goals of the LHCb experiment. Effects are predicted to be very small in the Standard Model but can be significantly enhanced in many models of new physics. We present the world's best measurement of the CP-violating phase $ϕ_s$ using $B_s^0\to J/ψKK$ and $B_s^0\to J/ψππ$ decays.
High-precision measurements performed by the LHCb collaboration have opened a new era in charm physics. Several crucial measurements, particularly in spectroscopy, rare decays and CP violation, can benefit from the increased statistical power of an upgraded LHCb detector. The upgrade of LHCb detector, its software infrastructure, and the impact on charm physics are discussed in detail.
Constraints on the CKM angle γare presented from GLW, ADS, and GGSZ analyses of B+- -> D K+- at the LHCb experiment. The branching fractions of B0 -> D0bar K+ π- and Bs -> D0bar K- π+ are also reported, measured relative to the related mode B0 -> D0bar π+ π-.
Following the intriguing hints of deviations from the Standard Model in rare B meson decays, searches for rare and forbidden decays of charm hadrons become a hot topic again. We present recent results on Flavour Changing Neutral Current $D^{0}\rightarrowμ^+ μ^-$, $D^0 \rightarrowμ^+μ^- π^+ π^-$, $D^{\pm}_{(s)}\rightarrow π^{\pm} μ^+μ^-$ and LFV $D^{\pm}_{(s)}\rightarrow π^{\mp}μ^{\pm}μ^{\pm}$ obtained at LHCb.
I present a measurement of the CKM angle gamma from a combination of three LHCb measurements using the tree decays B -> DK and B -> Dpi. These measurements are based on a dataset corresponding to 1.0fb-1, collected in 2011. In contrast to what was presented at FPCP, these proceedings fully include the effect of D0--D0b mixing on the combination. I also report on the inclusion of new, preliminary results on the Dalitz analysis of B->DK, D->KShh, using a dataset corresponding to 3fb-1, collected in 2011--2012.
LHCb is already providing leading measurements of time-dependent CP asymmetries with 1 fb$^{-1}$ of data. With the LHCb detector, and further one with the LHCb upgrade, very high-precision time-dependent CP measurements are expected to stringently test the CKM paradigm and to the search for possible small NP effects. A review of the current precision and the prospects for these time-dependent quantities with the LHCb and LHCb upgraded detectors are summarised in this paper.
Charm physics has been established at the LHC based on several high-precision measurements. The future of charm physics at the LHC experiments is discussed in detail. The bulk of the charm physics programme will be performed by LHCb and the LHCb upgrade. In particular, the impact of the LHCb upgrade on mixing and \CP violation measurements is presented.
The $B_c^\pm$ mass and lifetime measurements using the decay $B_c^\pm \to J/ψπ^\pm$ at the LHCb experiment were studied. About 310 signal events are expected for a data set which corresponds to an integrated luminosity of 1 fb$^{-1}$, with a $B/S$ ratio equal to 2. Based on these data, the $B_c^\pm$ mass and lifetime can be measured with expected statistical errors below 2 MeV/$c^2$ and 30 fs, respectively.
Decays of $B^0_s \to D_s^- π^+$ allow to determine the oscillation frequency $Δm_s$ between the $B^0_s$ particle and $\kern0.18em\overline{\kern -0.18em B}{}^0_s$ antiparticle states with high precision. It is a crucial input to constrain the CKM matrix and a manifestation of the quantum nature of physics. A new measurement of this frequency is presented, using a dataset corresponding to $6\,\mathrm{fb}^{-1}$ of $pp$ collisions, recorded by LHCb at a centre-of-mass energy of $13\,\mathrm{TeV}$. The oscillation frequency is determined to be $Δm_s = 17.7683\pm0.0051(\mathrm{stat.})\pm0.0032(\mat…
This document presents eight recent and new analyses from the LHCb experiment covering results on CKM angle $γ$ and high precision measurements on charm mixing parameters. In addition, the latest CP violation measurements in charm and beauty decays are reported.
The time-dependent CP-violating observables accessible through Bs->DsK decays have been measured for the first time using data corresponding to an integrated luminosity of 1 inverse fb collected in 2011 by the LHCb detector. Using these observables, the CKM angle gamma is determined to be (115 -43 +28) modulo 180 degrees at 68% CL, where the uncertainty contains both statistical and systematic components.
The LHCb experiment has a broad and varied physics programme, extending far beyond its core set of flavour physics measurements. This contribution summarises recent electroweak scale measurements and searches for exotic states in the dimuon final state.
The LHCb experiment has the unique possibility, among the LHC experiments, to be operated in fixed target mode, using its internal gas target SMOG. The energy scale achievable at the LHC and the excellent detector capabilities for vertexing, tracking and particle identification allow a wealth of measurements of great interest for cosmic ray and heavy ions physics. We report the first measurements made in this configuration: the measurement of antiproton production in proton-helium collisions and the measurements of open and hidden charm production in proton-argon collisions at $\sqrt{s_\textrm…
The LHCb experiment has opened the possibility to test mixing and $C\!P$ violation in the charm sector with unprecedented precision thanks to the huge number of charm hadron decays collected, $\mathcal{O}(10^8)$. The first observation of $C\!P$ violation in the decay of charm quarks in March 2019 has been a fundamental achievement. The latest LHCb measurements in the complementary sectors of mixing and time-dependent $C\!P$ violation are illustrated in these proceedings. In particular, a new measurement of the $C\!P$ violation parameter $A_Γ$ with 2015--2016 data that was presented for the fir…
In the present document a selected sample of the latest results on CP violation by the LHCb collaboration are presented. These include the first measurement of $ϕ_s^{c\overline{c}s} = 0.119 \pm0.107\pm0.034$ rad in a final state dominated by a tensor resonance, the most precise measurements of $C_{π^+π^-}$ and $S_{π^+π^-}$ to date, the first values ever measured of $C_{K^+K^-}$, $S_{K^+K^-}$ and $A_{K^+K^-}^{ΔΓ}$, the latest constraints on $γ= (76.8^{+5.1}_{-5.7})^\circ$ from the combination of several LHCb results and the first evidence for CP violation in baryonic mater at the level of 3.3$σ…
Precision measurements in charm physics offer a window into a unique sector of potential New Physics interactions. LHCb is poised to become a world leading experiment for charm physics, recording enormous samples with a detector tailored for flavor physics. This article presents recent charm production, CPV, and mixing studies from LHCb, including LHCb's first charm CP asymmetry measurement with 37 pb^-1 of data collected in 2010.
The LHCb experiment at the Large Hadron Collider specialises in high-precision measurements of flavour physics with hadrons containing $b$ and $c$ quarks. Lepton flavour universality tests provide an accurate and clear approach to scrutinising the Standard Model of particle physics. These proceedings report recent lepton flavour universality tests performed by the LHCb collaboration. For $b \to c \ell ν$ transitions, it includes the first simultaneous measurement of $R_{D^*}$ and $R_{D^{0}}$ at a hadron collider, an updated $R_{D^{*}}$ measurement with hadronic $τ$ decays using 2015-2016 data,…
The observable $\mathcal{R} ( D^{(*)} ) = \mathcal{B}\left( B^{0}\to D^{(*)-} τ^{+} ν_τ \right) / \mathcal{B}\left( B^{0}\to D^{(*)-} μ^{+} ν_μ \right)$ is a probe for Lepton Universality violation, so it is sensitive to New Physics processes. The current combination of the measurements of $\mathcal{R} ( D^{(*)} )$ differs from Standard Model predictions with a $4σ$ significance. A measurement of $\mathcal{R} ( D^* )$ using three-prong $τ$ decays is currently ongoing at LHCb. The statistical precision of this analysis is 6.7%, i.e. the smallest statistical uncertainty for a single measurement …
Measurements of the $B_s^0$ effective lifetime in decays to CP-odd and CP-even flavour specific final states allow to probe the width difference $ΔΓ_s$ and the CP-violating phase $ϕ_s$ of $B^0_s-\bar{B}^0_s$ mixing box-diagram. Measurements of the effective lifetime in the decay channels $B_s^0 \rightarrow K^+ K^-$ and $\bar{B}_s^0 \rightarrow J/ψf_0(980)$ are presented, as well as a measurement of $ΔΓ_s$ and $Γ_s$ performed by a tagged time-dependent angular analysis of $B_s^0 \rightarrow J/ψϕ$ decays and a measurement of the sign of $ΔΓ_s$, using data collected during 2011 with the LHCb dete…
We report results from the first measurements of the CKM angle $γ$ using $B\rightarrow DK$ decays with the LHCb experiment. Three well established methods are used to extract the CP observables. The updated measurement of $γ$ in the three-body $D^0$ Dalitz space results in $γ= (57\pm 16)^\circ$. When combining the observables from all \bdk studies, the best fit value for $γ\in [0,180]^\circ$ is $γ= 67.2^\circ$ with $γ\in [55.1,79.1]^\circ$ at 68%CL and $γ\in [43.9, 89.5]^\circ$ at 95%CL. This represents the most precise $γ$ values directly measured by a single experiment. Furthermore, a new ti…
Soft QCD and double parton scattering are of great interest in high energy physics. They are both actively studied at the LHCb experiment. The measurement of the central exclusive production of $J/ψ$ and $ψ(2S)$ mesons in $pp$ collisions at $\sqrt{s} = 13 \,{\mathrm{TeV}}$ is presented. The result shows good agreement with the theoretical predictions. The measurement of the $J/ψ$ pair production cross-section in $pp$ collisions at $\sqrt{s} = 13 \,{\mathrm{TeV}}$ is reported. The differential cross-sections as functions of various kinematic variables are compared to the theoretical predictions…
In this proceeding I present the latest result by the LHCb collaboration in determining the CKM angle $γ$ ($(73^{+9}_{-10})^{\circ}$). The result is determined by combining several $B \to Dh$ analyses, and the latest results from the decay time dependent $B_{s} \to D_{s}K$ analysis. A few other decay channels interesting for determination of $γ$ in the future is also discussed. These results were presented earlier as a poster at the 50 years of CP violation conference, London, UK.
A recent LHCb measurement of the CP violating flavour specific asymmetry in $B_s^0$ decays, \asls, is presented. This measurement is based on a data sample corresponding to an integrated luminosity of 1 fb$^{-1}$ of $pp$ collisions at $\sqrt{s}$ $=$ 7 TeV, collected during the 2011 run of the LHC. The result is $\asls = (-0.24 \pm 0.54_{\rm stat} \pm 0.33_{\rm syst})\times 10^{-2}$, which is the most precise measurement of this quantity to date and agrees with the Standard Model prediction.}
The production of c c_bar and b b_bar is studied in pp collisions at sqrt(s) = 7 TeV with the LHCb detector. The results of these measurements are compared with different theoretical models. Results and prospects are also shown for exotics: the mass measurement of the X(3872) and the search of the X(4140). Most of the presented results are based on the 2010 LHCb dataset (35 pb-1).
Constraints on new physics in the electroweak sector are limited by the precision of direct measurements of the $W$ boson mass ($m_W$). A new measurement is hereby reported, using proton-proton collision data recorded by the LHCb experiment in 2016 at $\sqrt{s}=13$ TeV, corresponding to roughly 1.7 $\textrm{fb}^{-1}$ of integrated luminosity. From a simultaneous fit of the muon $q/p_{\mathrm{T}}$ distribution from $W \to μν$ decays and the $ϕ^{\ast}$ distribution from $Z \to μμ$ decays, $m_W$ is measured to be \begin{equation*} m_W = 80354 \pm 23_{\textrm{stat}} \pm 10_{\textrm{exp}} \pm 17_{\…
We report on the perspective measurements of inclusive particle production in high-energy p-p collisions with data to be collected by the LHCb experiment at CERN's LHC. These include V0 and D meson production studies, which can be based on a minimum bias sample, as well as charmonia production studies, which need a muon-triggered samples. Using reconstructed $J/ψ\to μ^+ μ^-$ decays, both the prompt $J/ψ$ and $b\to J/ψ$ production cross-sections will be determined, in the forward pseudo-rapidity range of 2-5 covered by LHCb. Due to the large production rate, such analyses will be possible with …
Two measurements of mixing and $CP$ violation in charm decays performed at the LHCb experiment are presented. The former is a measurement of the mixing observable $y_{CP}-y_{CP}^{Kπ}$ in two-body $D^0$ decays, while the latter is a search for direct $CP$ violation in $D^+_{(s)}\rightarrowη^{(')}π^+$ decays.
A search for $Σ^+ \to p μ^+ μ^-$ decays with LHCb Run 1 data is presented, yielding an evidence for this decay and a measurement of a branching fraction compatible with the Standard Model. The HyperCP anomaly in the dimuon invariant mass distribution is not confirmed, and its branching fraction central value is excluded at 95\% CL. Prospects for the future of this measurement in LHCb are also presented.
Inclusive c and b-jet tagging algorithms have been developed to utilize the excellent secondary vertex reconstruction and resolution capabilities of the LHCb detector. The validation and performance of these tagging algorithms are reported using the full run 1 LHCb dataset at 7 and 8 TeV. Jet-tagging has been applied to muon+jet final states to measure both the W+c,b-jet charge asymmetries and the ratios of W+c,b-jet to W+jet and W+jet to Z+jet production. The forward top production cross-section is also measured using the muon+b-jet final. All results are found to be consistent with standard …
