34 pages, 13 figures. Lectures given at the 69th Scottish Universities Summer School in Physics in St. Andrews, UK, 2012. v2 with minor corrections for proofs
These lectures give a topical review of heavy flavour physics, in particular \CP violation and rare decays, from an experimental point of view. They describe the ongoing motivation to study heavy flavour physics in the LHC era, the current status of the field emphasising key results from previous experiments, some selected topics in which new results are expected in the near future, and a brief look at future projects.
Models incorporating flavoured dark matter provide an elegant solution to the dark matter problem, evading the tight LHC and direct direction constraints on simple WIMP models. In Dark Minimal Flavour Violation, a simple framework of flavoured dark matter with new sources of flavour violation, the constraints from thermal freeze-out, direct detection experiments, and flavour physics create well-defined benchmark scenarios for these models. We study the LHC phenomenology of four such scenarios, focusing on final states where a single top quark is produced accompanied by no jets, one jet from th…
Heavy flavour physics provides excellent opportunities to indirectly search for new physics at very high energy scales and to study hadron properties for deep understanding of the strong interaction. The LHCb experiment has been playing a leading role in the study of heavy flavour physics since the start of the LHC operations about ten years ago, and made a range of high-precision measurements and unexpected discoveries, which may have far-reaching implications on the field of particle physics. This review highlights a selection of the most influential physics results on CP violation, rare dec…
Recent measurements have revealed a number of intriguing deviations from the Standard Model predictions in $B$ meson decays, in particular in observables testing lepton flavour universality. We review their experimental status and theoretical description in terms of effective Hamiltonians. We also discuss possible new physics interpretations in terms of simplified models and summarise their status in view of the stringent constraints from flavour physics and high-$p_T$ collider searches.
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…
We study the impact of an additional $U(1)'$ gauge symmetry with flavour-dependent charges for quarks and leptons on the LHC flavour anomalies observed in $B \to K^* μ^+μ^-$, $R(K) = B \to K μ^+μ^-/B \to K e^+e^-$, and $h \to μτ$. In its minimal version with two scalar doublets, the resulting model naturally explains the deviations from the Standard Model observed in $B \to K^* μ^+μ^-$ and $R(K)$. The CMS access in $h \to μτ$ can be explained by introducing a third scalar doublet, which gives rise to a prediction for $τ\to 3μ$. We investigate constraints from flavour observables and direct LHC…
The LHC observed deviations from the Standard Model (SM) in the flavour sector: LHCb found a $4.3\,σ$ discrepancy compared to the SM in $b\to sμμ$ transitions and CMS reported a non-zero measurement of $h\toμτ$ with a significance of $2.4\,σ$. Here we discuss how these deviations from the SM can be explained, focusing on two models with gauged $L_μ-L_τ$ symmetry. The first model contains two scalar doublets and vector-like quarks while the second one employs three scalar doublets but does not require vector-like fermions. In both models, interesting correlations between $b\to sμμ$ transitions,…
We consider models of supersymmetry which can incorporate sizeable mixing between different generations of sfermions. While the mixing is constrained by the non-observation of various flavour changing neutral current (FCNC) processes, there exist regions of SUSY parameter space where the effects of such mixing can be probed at colliders. In this work, we explore this possibility by focussing on the slepton sector. The sleptons are produced through cascade decays in direct neutralino-chargino ($χ_2^0χ_1^\pm$) pair production at the LHC. The final state is characterized by 3 leptons and missing …
Run-I results from the CMS collaboration show an excess of events in the decay $h \to μτ_e$ with a local significances of 2.4$σ$. This could be the first hint of flavour violation in the Higgs sector. We summarise the bounds on the flavour violating Yukawa couplings from direct searches, low energy measurements and projected future experiments. We discuss the sensitivity of upcoming HL-LHC runs and future lepton colliders in measuring lepton-flavour violating couplings using an effective field theory framework. For the HL-LHC we find limits on BR($h\to μτ$) and BR$(h\to e τ) \lesssim \mathcal{…
在最小超对称标准模型（MSSM）中，研究了夸克世代混合对夸克和胶子产生和衰变的影响，重点研究了第二代和第三代夸克的混合.考虑到从B-物理实验的限制，我们表明，在参数空间中存在的各种区域的夸克和/或胶子衰变到夸克味违反（QFV）的最终状态可以有大的分支比。这里我们考虑正方体的费米子衰变和玻色子衰变。相应的QFV信号的速率，例如pp -> t t bar{c} bar{c} missing-E_T X，在LHC（14 TeV）处可以是显著的。我们发现，列入味混合效应可以是重要的搜索的方和胶子和确定的MSSM在LHC的基本模型参数。
The direct searches for Beyond Standard Model (BSM) particles have been constraining their mass scale to the extent where it is now becoming consensual that such particles are likely to be above the energy reach of the LHC. Meanwhile, the studies of indirect probes of BSM physics, with all their diversity, have been progressing both in accurracy and in setting up observables with reduced theoretical uncertainties. The observation of flavour anomalies in $b$ hadron decays represents an important part of the program of indirect detection of BSM physics. Several benchmark analyses involving lepto…
Flavour-changing neutral-current interactions of the top quark can be searched for in top-quark pair production with one top quark decaying to an up-type quark and a neutral boson, and they can be searched for in the single production of a top quark in association with such a boson. Both processes interfere if an additional up-type quark is produced in the case of single production. The impact of these interference effects on searches for flavour-changing neutral currents at the LHC is studied for the case where the neutral boson is a photon or a $Z$ boson. Interference effects are found to be…
The pp collision data collected in the LHC Run I provides a great opportunity for heavy flavour studies. The latest results on exotic states, heavy baryon and $B_c^+$ mesons are reviewed.
Motivated by the principle of natural flavour conservation, searches for signatures of a second scalar doublet at the LHC are usually limited to models with a very restricted Yukawa structure. Strong correlations between the scalar couplings to fermions are fixed in these models due to the underlying flavour principle, making the results obtained from such analyses highly model dependent. Moreover, constraints derived from flavour experiments also vary radically within the different models considered. The hypothesis of Yukawa alignment provides a suitable framework to perform a more general an…
Heavy flavour production measurements in pp collisions are a crucial test of QCD. The LHC experiments ALICE, ATLAS, CMS and LHCb, provide complementary abilities to measure many aspects of heavy-flavour production. This contribution summarises recent LHC measurements within this topic.
A summary of results in heavy flavour physics from Run 1 of the LHC is presented. Topics discussed include spectroscopy, mixing, CP violation and rare decays of charmed and beauty hadrons.
A range of flavour physics observables show tensions with their corresponding Standard Model expectations: measurements of leptonic flavour-changing neutral current processes and ratios of semi-leptonic branching fractions involving different generations of leptons show deviations of the order of four standard deviations. If confirmed, either would be an intriguing sign of new physics. In this manuscript, we analyse the current experimental situation of such processes and for the first time estimate the combined impact of the future datasets of the Belle II and LHCb experiments on the present …
We report on our re-calculation of electroweak top-quark pair production in Standard Model extensions with extra heavy neutral and charged spin-1 particles at the LHC with substantial improvements. In particular, we allow for flavour--non-diagonal $Z'$ couplings and take into account non-resonant production in the Standard Model and beyond. As in our previous work we include NLO QCD corrections and match to parton showers with the POWHEG method fully taking into account the Standard Model and new physics interference effects. We consider the Sequential Standard Model, the Topcolour model as we…
We point out that the stringent lower bounds on the masses of additional electrically neutral and charged Higgs bosons crucially depend on the flavour structure of their Yukawa interactions. We show that these bounds can easily be evaded by the introduction of flavour-changing neutral currents in the Higgs sector. As an illustration, we study the phenomenology of a two Higgs doublet model with a Yukawa texture singling out the third family of quarks and leptons. We combine constraints from low-energy flavour physics measurements, LHC measurements of the 125 GeV Higgs boson rates, and LHC searc…
This work presents the latest results on open heavy-flavour production in proton-proton, proton-lead, lead-lead and xenon-xenon collisions from the ALICE, ATLAS, CMS and LHCb Collaborations at the LHC.
Heavy-flavour quarks are important to probe Quark-Gluon Plasma(QGP) properties. Cold Nuclear Matter(CNM) effects can be accessed by $p$Pb collisions. LHCb is a heavy-flavour precision experiment and has collected large collision data samples. Production cross-section measurements of prompt $D^{0}$ at $\sqrt{s_\mathrm{NN}}$= 5 TeV and $J/ψ$ at $\sqrt{s_\mathrm{NN}}$= 8.16 TeV are presented.
In this paper we study the production of a heavy charged Higgs boson in association with heavy quarks at the LHC, in a type-II two-Higgs-doublet model. We present for the first time fully-differential results obtained in the four-flavour scheme at NLO accuracy, both at fixed order and including the matching with parton showers. Relevant differential distributions are studied for two values of the charged boson mass and a thorough comparison is performed between predictions obtained in the four- and five-flavour schemes. We show that the agreement between the two schemes is improved by NLO(+PS)…
In ALICE, open heavy-flavour production is studied through the measurements of the leptons (electrons and muons) from heavy-flavour hadron decays at central and forward rapidity and via the reconstruction of D-meson hadronic decays at mid-rapidity. An overview of the open heavy-flavour production with ALICE in pp ($\sqrt{s}$ = 2.76 TeV and 7 TeV), p--Pb ($\sqrt {s_{\rm NN}}$ = 5.02 TeV) and Pb--Pb ($\sqrt {s_{\rm NN}}$ = 2.76 TeV) collisions will be presented. We will discuss the production cross sections, modifications of the transverse momentum distributions, azimuthal anisotropic emissions …
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 ALICE detector is well suited to measure heavy-flavour (charm and beauty) production via hadronic and semi-leptonic decay channels of heavy-flavour particles. Here an overview of heavy-flavour measurements made with the ALICE detector during Run 1 in pp and p--Pb collisions is presented and discussed.
The Anatomy of Quark Flavour Observables in 331 Models in the Flavour Precision Era
即将到来的味道精确时代将允许在不同的新物理（NP）场景中发现各种味道违反模式，这些场景目前被强子和实验不确定性所淘汰。基于规范群SU（3）_C X SU（3）_L X U（1）_X，我们通过对331个模型中的味破坏进行解剖来说明这一点，这些模型是具有新的味源和CP破坏的最简单的NP场景之一。后者主要起源于普通夸克和轻子与新的重Z '规范玻色子的味破坏相互作用。在对这些模型作了一般性的讨论之后，我们在假定CKM和强子参数的不确定性比现有模型小得多的情况下，详细研究了特定的β = 1/\sqrt{3}模型（以后称之为overline {331}模型）中Delta F = 2的可观测量和稀有的K、B介子衰变。在我们的分析中，最突出的作用是B_s-> mu ^+ mu ^-中的δ_K、Δ M_q（q = d，s）、混合诱导的CP不对称性S_{psi K_S}和S_{psi phi}、稀有衰变B_{s,d}-> mu ^+ mu ^-，特别是CP不对称性S_{mu^+ mu^-} ^s。我们确定了一些不同的CMFV模型已知的各种观测值之间的相关性。虽然，Delta F = 2观测值仍然允许在新的参数空间中的四个绿洲，我们演示了如何包含Delta F = 1观测值可以在未来确定该模型的最佳绿洲。对于1 TeV <= M_{Z'} <= 3 TeV，超线{331}模型与B ^+-> tau ^+…
This thesis discusses recent advances in precision calculations of quantum chromodynamics and their application to the Large Hadron Collider (LHC) physics program and beyond.
The measurements of open heavy-flavours, i.e. D mesons at central rapidity and leptons from charm and beauty decays at central and forward rapidity was studied in p-Pb collisions at $\sqrt{s_{\rm{NN}}}$ = 5.02 TeV using the ALICE detector. The results are presented and compared to model predictions including cold nuclear matter effects.
Two-particle azimuthal correlations of electrons from heavy-flavour hadron decays with charged particles can give insight into the properties of heavy-quark production and hadronization into heavy-flavour jets.\\ In this contribution, the ALICE results measured in pp collisions at 5.02 TeV, collected in the LHC Run 2, are presented. The yields of charged particles in the near and away-side correlation peaks and the peak width are compared with PYTHIA calculations.
The Anatomy of Z' and Z with Flavour Changing Neutral Currents in the Flavour Precision Era
SM的最简单的扩展通常会引入新的味源和CP破坏以及右手流，这就是在SM规范群中加入U（1）规范对称性。如果相应的重规范玻色子Z'介导的FCNC过程中的夸克部门在树级，这些新的物理贡献意味着一种模式的偏差，从SM的预期FCNC过程只取决于Z'耦合到费米子和它的质量。这意味着Δ F=2和Δ F=1观测值之间的严格相关性，这些观测值决定了Z '模型允许的参数空间的景观。预计风味精度时代（FPE）摆在我们面前，我们说明了这一点，通过搜索允许绿洲在这一景观假设显着较小的不确定性CKM和强子参数比目前可用。为此，我们分析了K^0-bar K^0和B^0_{s，d}-bar B^0_{s，d}系统中的Delta F=2观测值，以及罕见的K和B衰变，包括各种组合的左手和右手Z '-夸克耦合。我们确定了各种风味可观察值之间的一些相关性，这些风味可观察值可以测试和区分这些不同的Z'场景。强调了b->s l^+ l^-和b->s nu bar nu跃迁在这些研究中的重要作用。在M_Z '<3 TeV的条件下，在B_{s,d}和K介子系统中，由于施加了现有的味约束，出现了与SM期望值偏离的丰富模式.当M_Z '> 5 TeV时，在罕见的B_{s,d}衰变中发现Z'效应通常低于10%，甚至在FPE中也很难测量，而K->pi nu bar nu和K_L-> pi ^0 l^+ l^-衰变则提供了一个重要的入口…
We present calculations of the chemical freeze-out temperature (T_ch) based on particle yields from STAR and ALICE measured at collision energies ranging from sqrt{s_{NN}} = 11.5 GeV to 5.02 TeV. Employing the Grand Canonical Ensemble approach using the Thermal-FIST Hadron Resonance Gas model package, we show evidence for a flavour-dependent chemical freeze-out in the crossover region of the QCD phase diagram. At a vanishing baryochemical potential, we calculate light and strange flavour freeze-out temperatures T_L = 150.2 +- 2.6 MeV and T_S = 165.1 +- 2.7 MeV, respectively.
