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 very small integrated luminosities of the order of a few $\mathrm{pb}^{-1}$. Other charmonia related measurements will also be discussed, such as that of the $J/ψ$ polarization at production or of the production of some of the new X, Y and Z states.
We see copious production of charmed hadrons in the early LHCb data. The status and plans for charm production studies at LHCb are discussed, and preliminary signals are shown.
Central Exclusive Production is a unique QCD process in which particles are produced via colourless propagators. Several results have been obtained at LHCb for the production of single charmonia, pairs of charmonia, and single bottomonia.
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 installation of a new sub-detector has improved the ability of LHCb to measure central exclusive production in Run 2 at the LHC. A measurement of central exclusive $J/ψ$ production is presented and improvements for the analysis of hadronic final states are discussed.
We summarize the main measurements performed with the LHCb detector on production and spectroscopy in the heavy flavour sector, using data samples recorded during 2010 and 2011 data taking in proton-proton collisions at $\sqrt s=7$\,TeV .
Studies of electroweak boson production at LHCb are detailed and discussed. Proposed signal selection schemes and background suppression strategies are described and the projected performance is estimated using Monte Carlo data. Due to the unique pseudorapidity coverage and triggering capabilities of LHCb, these studies will probe an unexplored region of x, Q^2 space.
Results for $W$ and $Z$ boson production from $pp$ collisions at $\sqrt{s} = 7$ TeV in the LHCb experiment are presented. Due to LHCb's unique forward acceptance in pseudorapidity of $2.0 \leq η\leq 4.5$ these results are a test of the Standard Model in the forward region, and can be used to better constrain parton density functions in the low $x$ kinematic regime.
We report on an indirect method being used to measure luminosity at LHCb. It involves recording the event rate of elastic diphoton dimuon production. Preliminary MC studies suggest that with 1 fb^{-1} of data this method could provide a luminosity measurement with a precision of better than 2%
The search for central exclusive production of muon pairs is performed using the LHCb data acquired on 2011 ($\sqrt{s} = 7$ TeV) and 2012 ($\sqrt{s} = 8$ TeV). Preliminary measurements of cross section using these samples are showed and a first comparison with theoretical previews is presented.
Central exclusive J/ψ and χc meson production has been measured in decays to dimuons with the LHCb detector, in data corresponding to 36 /pb of integrated luminosity from \sqrt{s} = 7 TeV proton-proton collisions. Cross-section measurements for J/ψ, ψ(2S) and χc0,c1,c2 production are presented, and the J/ψ photoproduction cross-section is measured as a function of the photon-proton centre-of-mass energy and compared to measurements made at HERA.
The LHCb detector and LHC running conditions are ideally suited to measuring central exclusive production. Several recent measurements of exclusive dimuon, single and double charmonia are reviewed. The potential for future measurements across a broad range of physics channels is discussed.
The vast amount of $c\overline{c}$ production that can be recorded by the LHCb detector makes it an ideal environment to study the hadronic production of charmed baryons, along with the properties of their decays. We briefly describe the LHCb experiment and the triggering mechanisms it uses for recording charm production. Previous charmed baryon results from LHCb are detailed, with a description of the future plans for the charmed baryon programme.
Central Exclusive Production (CEP) is a unique process at hadron machines in which particles are produced via colourless propagators. LHCb have measured the cross-sections for the CEP of vector mesons, $J/ψ,ψ(2S),Υ(1S),Υ(2S)$ and $Υ(3S)$, which are photo-produced. In the double pomeron exchange process, preliminary measurements have been made of $χ_{c0},χ_{c1}, χ_{c2}$ meson production while the first observations of the CEP of pairs of charmonia, $J/ψJ/ψ$ and $J/ψψ(2S)$, have been made and limits obtained on the pair production of other charmonia.
Forward top production is observed, in the $μ+b$ final state, with the 3 fb$^{-1}$ Run I dataset collected by the LHCb detector. The combined cross-section for $t\bar{t}$ and single top production at $\sqrt{s}=7$ TeV and $\sqrt{s}=8$ TeV is measured, for muons from the W boson with $p_{\rm T} > 25$ GeV in the pseudo-rapidity range 2.0$< η<$4.5 and with a b-tagged jet with 50$ < p_{\rm T} < 100$ GeV in the pseudorapidity range 2.2$< η<$4.2. The production cross-sections are found to be in agreement with NLO predictions.
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 ->JPsi+X 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-pi+, D0 K-pi+pi0, LambdaC+ -> p K-pi+ and D+ ->Ks0 pi+ and their prospects.
The LHCb collaboration has measured central exclusive production of $J/ψ$, $ψ(2S)$, and $Υ$ mesons as well as $J/ψJ/ψ$, $J/ψψ(2S)$, $ψ(2S)ψ(2S)$, and $χ_cχ_c$ meson pairs in proton-proton collisions. The analyses of $Υ$ and charmonium pairs are performed at the centre-of-mass energies of 7 TeV and 8 TeV, and those of $J/ψ$ and $ψ(2S)$ are done at 7 TeV and 13 TeV. The analysis at 13 TeV involves the use of new shower counters. These allow a reduction in the background by vetoing events with activity in an extended region in rapidity. The measurements of central exclusive production at LHCb are…
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.
Measurements of the X(3872) mass, $ψ(2S)$ production cross-section and $χ_{c2}/χ_{c1}$ production ratio using around 35$\rm pb^{-1}$ of pp collision data at $\sqrt{s}$ = 7 TeV during the 2010 LHC running period with the LHCb detector are presented.
The LHCb detector at the LHC offers unique coverage of forward rapidities for studies of Central Exclusive Production (CEP) and soft QCD. CEP measurements allow the investigation of the nature of pomerons, and provide constraints on low-x gluon phenomenology, probing potential saturation effects. Moreover LHCb can test phenomenological models of soft QCD processes, by measuring the production of forward hadrons in pp collisions. In these proceedings the latest results from the LHCb experiment will be presented.
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.
This article presents recent results of the Z boson production in the proton-lead collisions and the charmonium production in the ultra-peripheral lead-lead collisions at the LHC collected during 2013 to 2018 by the LHCb detector. The potential heavy ion programs in these topics are also discussed.
The LHCb experiment at the LHC is fully instrumented over a unique pseudorapidity range in the forward region. Although it has been designed for b-physics, LHCb is able to provide valuable informations on particle production in this region of phase space. Therefore QCD studies have been performed with the LHCb detector on pp collisions at \sqrt(s)=900 GeV and \sqrt(s)=7 TeV. The measurement of charged particles multiplicity at \sqrt{s}=7 TeV}, \bar(Lambda)/Lambda, \bar(Lambda)/K_s^0 production ratios at \sqrt(s)=900 GeV and \sqrt(s)=7 TeV, as well as light hadrons (p,K,pi) production ratios at…
I will review a selection of LHCb results on the production of heavy quarkonium states in pp collisions, including the recent results on J/psi and Y(nS) (n=1,2,3) production at sqrt(s)=8TeV, as well as preliminary results on J/psi production in proton-lead collisions at sqrt(s_NN)=5TeV.
We argue that the recent LHCb observation of J/psi-pair production indicates a significant contribution from double parton scattering, in addition to the standard single parton scattering component. We propose a method to measure the double parton scattering at LHCb using leptonic final states from the decay of two prompt J/psi mesons.
Detailed results on top quark production at LHCb are reported from the first observation of top production in a forward region detector to the first measurement of top pair production at LHCb with 13 TeV data.
Measurements of electroweak boson production provide an important test of the Standard Model at the LHC energies and allow the partonic content of the proton to be constrained. $W$ and $Z$ bosons are reconstructed in several leptonic final states using data samples corresponding to an integrated luminosity of up to about 1 $fb^{-1}$. Inclusive and associated production cross-sections are reported.
The LHCb experiment started its physics program with the 37/pb of pp collisions at 7 TeV c.m. energy delivered by the LHC during 2010. The performances and capability of the experiment, conceived for precision measurements in the heavy flavour sector, are illustrated through the first results from the experimental core program. A rich set of production studies provide precision QCD and EW tests in the unique high rapidity region covered by LHCb. Notably, results for W and Z production are very encouraging for setting constraints on the parton PDFs.
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 detector covers the forward angular region complementary to the angular coverage by the general purpose LHC experiments. With the first data, measurements of inclusive charged particle production and V^0 production will be performed and compared to particle production models. Focusing on ratios, such as positives/negatives or lambda-bar/lambda, many systematic effects cancel and publishable results are expected soon after the turn-on of LHC. The talk will present the analysis strategies, the physics questions and the results expected from the first 10^8 minimum bias pp-collisions at a…
Measurements of coherent charmonium production cross sections together with their ratio in ultra-peripheral PbPb collisions are studied at a nucleon-nucleon centre-of-mass energy of $5.02\,\mathrm{TeV}$, the differential cross-sections are measured as a function of rapidity and transverse momentum, separately. The photo-production of \jpsi mesons at low transverse momentum is studied in peripheral PbPb collisions, which confirms coherent \jpsi production in hadronic collisions. These latest results significantly improve previous measurements and are compared with some theoretical predictions.
This article presents results of the Z boson production in the proton-lead collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV and $\sqrt{s_{\rm NN}}= 8.16$ TeV collected in 2013 and 2016, respectively, by the LHCb detector at the LHC in forward and backward rapidity. The great precision of the 2016 data are found compatible with nPDFs theoretical predictions within large theoretical uncertainties, and can be useful to constraint new predictions.
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…
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.
A large data set collected at the LHCb experiment in proton-proton collisions during Runs 1 and 2 of the Large Hadron Collider has opened a unique possibility to study heavy beauty hadron states and to broaden knowledge of their spectroscopy and production. Recent results on searches for new excited $\mathrm{b}$-hadron states, and studies of $\mathrm{b}$-hadron production, are reviewed. In particular, the observation of new excited $Ω^-_{\mathrm{b}}$ states, the observation of two new narrow $Λ_{\mathrm{b}}(6146)^0$ and $Λ_{\mathrm{b}}(6152)^0$ states, the observation of new $Λ_{\mathrm{b}}^{*…
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.
The production of $J/ψ$ and $Υ$ mesons decaying into dimuon final state is studied at the LHCb experiment, with rapidity in the range of (1.5, 4.0) or (-5.0, -2.5) in proton-lead collisions at a nucleon-nucleon centre-of-mass energy $\sqrt{s_{NN}}$ = 5 TeV, based on a data sample corresponding to an integrated luminosity of 1.6 /fb. The nuclear modification factor and forward-backward production ratio are determined for prompt $J/ψ$, $J/ψ$ from b-hadron decay and $Υ(1S)$ mesons in study of the cold nuclear matter effects.
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.
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 …
High-precision electroweak production measurements from the Tevatron and the LHC provide important constraints on the quark flavor separation in global PDF fits. In this contribution, we study the impact of the recent D0 W asymmetry measurements and of the LHCb W and Z Run I combination in the global NNPDF analysis. We find that these measurements can be described by NLO QCD theory and that they lead to a significant reduction of PDF uncertainties.
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 impact of recent measurements of heavy-flavour production in deep inelastic $ep$ scattering and in $pp$ collisions on parton distribution functions is studied in a QCD analysis in the fixed-flavour number scheme at next-to-leading order. Differential cross sections of charm- and beauty-hadron production measured by LHCb are used together with inclusive and heavy-flavour production cross sections in deep inelastic scattering at HERA. The heavy-flavour data of the LHCb experiment impose additional constraints on the gluon and the sea-quark distributions at low partonic fractions $x$ of the p…
The LHCb recorded $\sim$ 210 $μb^{-1}$ integrated luminosity of PbPb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV in 2018. With an increase of the luminosity by a factor of 20 compared to the previous 2015 PbPb dataset, precise measurements on photo-produced charmonia in ultra-peripheral collisions are now possible. Moreover, the great momentum resolution of the detector allows photo-produced $J/ψ$ in collisions with a nuclear overlap to be studied. This new type of probe is sensitive to the geometry of the collisions but also to the electromagnetic field of the Pb nuclei. In this contribution, we…
Measurements of quarkonia production in ultra-peripheral heavy-ion collisions are of important value to study photon-photon and photon-nucleus interactions, the partonic structure of nuclei, and mechanisms of vector-meson production. LHCb has studied both coherent $J/ψ$ and $ψ(2S)$ mesons in ultra-peripheral collisions using PbPb data at forward rapidity with the highest precision currently accessible. In addition, measurements of $Z$ production in $p$Pb collisions provide new constraints on the partonic structure of nucleons bound inside nuclei. Here will present these measurements of quarkon…
The cross-sections of coherent \jpsi and \psitwos production in ultra-peripheral PbPb collisions at a nucleon-nucleon center-of-mass energy of $5.02\,\mathrm{TeV}$ are measured using a data sample collected in 2018 at $\lhcb$, and the differential cross-sections are measured separately as a function of transverse momentum and rapidity. The photo-production of \jpsi mesons at low transverse momentum is studied in peripheral PbPb collisions, \jpsi candidates are reconstructed through the prompt decay into \mumu in the rapidity region of $2.0<y<4.5$. These results significantly improve previous m…
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 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…
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…
Because of its forward coverage, LHCb can probe the valence quark distributions of protons and nuclei at small and large Bjorken-x with high precision. This proceeding presents new LHCb measurements of Z boson production in association with charm jet in the forward region of proton-proton collisions and Z boson production in proton-lead collisions. Z+charm jet production could be sensitive to a valence-like intrinsic-charm component in the proton wave function. The measurements of Z production in proton-lead collisions provide new constraints on the partonic structure of nucleons inside nuclei…
We quantify the constraints on the flavour separation between the quarks and antiquarks in the proton provided by the recent forward weak gauge boson production data from the LHCb experiment at $\sqrt{s}=7$ and 8 TeV. Performed in the framework of the NNPDF3.1 global analysis, this study highlights the key role that the LHCb W and Z data have in achieving a robust quark flavour separation in the large-x region, including the strange and charm quarks. We demonstrate how the LHCb measurements lead to improved determinations of the the up and down quark PDFs in the region $x\ge 0.1$, with an unce…
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.
These proceedings summarize the LHCb measurements of charm- and beauty-hadron production in pPb collisions. The studies are made down to very low-\pt of the observed heavy-flavor hadrons using fully reconstructed decays. Nuclear matter effects are quantified via nuclear modification factors and forward-backward production ratios. A strong suppression is observed at positive rapidity (proton beam direction), while a modest or no suppression is seen for the backward rapidity (lead beam direction). The nuclear parton distributions of the lead nucleus is constrained down to Bjorken-$x\sim10^{-5}$,…
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.
The small-$x$ gluon in global fits of parton distributions is affected by large uncertainties from the lack of direct experimental constraints. In this work we provide a precision determination of the small-$x$ gluon from the exploitation of forward charm production data provided by LHCb for three different centre-of-mass (CoM) energies: 5~TeV, 7~TeV and 13~TeV. The LHCb measurements are included in the PDF fit by means of normalized distributions and cross-section ratios between data taken at different CoM values, $R_{13/7}$ and $R_{13/5}$. We demonstrate that forward charm production leads t…
Studies of semileptonic decays of b hadrons with the LHCb experiment are reported. In particular, measurements of the b hadron production fractions at the LHC and Bs semileptonic decays in P-wave charmed mesons are presented. An outlook of the LHCb potential in measuring the CKM matrix elements Vub and Vcb, as well as decays involving taus, is given.
