We consider longitudinal, parity-violating single-spin asymmetries in proton-proton collisions at RHIC. The focus of this study is on the production of single-inclusive jets, as well as on jets that contain a charm quark. While the asymmetry for inclusive jets turns out to be small, we find considerably larger effects for the case of charm production. We also investigate the role of leading threshold logarithms and find that they increase the polarized and unpolarized cross sections and reduce the spin asymmetry.
Transverse single-spin asymmetries (SSA) are expected to be small in perturbative QCD because of the chiral nature of the theory. Experiment shows large transverse SSA for particle produced in special kinematics. This contribution reviews the experimental situation and provide an outlook for future measurements.
In this review a first comprehensive study of azimuthal asymmetries in semi-inclusive deep inelastic muoproduction of hadron pairs off longitudinally polarized protons at COMPASS is presented. The study is based on data taken in 2007 and 2011, obtained by impinging a high-energetic $μ^+$ beam of $160$ GeV/$\it{c}$, respectively $200$ GeV/$\it{c}$, momentum on a solid ammonia target. The discussion is focused on both leading and subleading longitudinal target-spin-dependent asymmetries arising in the di-hadron SIDIS cross section, addressing the role of spin-orbit couplings and quark-gluon corr…
Preliminary results obtained by the COMPASS experiment for longitudinal-spin-dependent azimuthal asymmetries in single-hadron muoproduction off protons are presented for the first time. The analysis was carried out on the full data sample collected by COMPASS with longitudinally polarized proton ($NH_3$) target in 2007 and 2011 using 160~\gvc and 200~\gvc muon beams, correspondingly. Within QCD parton model approach extracted asymmetries are giving access to the specific convolutions of certain transverse-momentum-dependent \textit{twist-2} and \textit{higher twist} parton distribution functio…
We evaluate the single target-spin sin(phi_h) and sin(2ϕ_h) azimuthal asymmetries in the semi-inclusive deep inelastic lepton scattering off longitudinally polarized proton target under HERMES kinematic conditions. A good agreement with the HERMES data can be achieved using only the twist-2 distribution and fragmentation functions.
We study the single-spin asymmetries of pions produced in semi-inclusive deep-inelastic scattering on the longitudinally polarized nucleon targets. We particularly consider the effects of the twist-3 transverse-momentum dependent distribution functions $f_L^\perp$ and $h_L$ to the asymmetry. We calculate the asymmetric moment $A_{UL}^{\sinϕ_h}$ for $π^+$, $π^-$ and $π^0$ produced off the proton target at HERMES and compare the results with the HERMES data. We also present the prediction of the same asymmetries for different pions at the kinematics of CLAS 5.5 GeV on a proton target, as well as…
The double longitudinal-spin asymmetry, $A_{LL}$, of the $J/ψ$ production in polarized proton-proton collisions is presented in this paper at QCD next-to-leading order. It is found that the obtained values of $A_{LL}$ are in general consistent with the PHENIX measurements. Various sets of the long-distance matrix elements (LDMEs) are employed in our calculation to study the possible theoretical uncertainties. It is found that, for $p_t<5\gev$, all these LDMEs lead to almost the same results, which are within the tolerance of the experimental data uncertainties.
We investigate the single-spin asymmetries in inclusive and exclusive processes of electron-proton scattering and electron-positron annihilation. In the decomposition of hadronic tensor, a Lorentz symmetric spin-dependent term is generally present. The existence of such a term implies single-spin asymmetries in these processes and these single-spin asymmetries for baryons can be understood in a unified manner. We argue that it is important to measure the single-spin asymmetries in both inclusive and exclusive processes for the $Λ$ production at the present B-factories. This will lead to the fi…
We analyze single transverse-spin asymmetries for hadronic pion production at large transverse momenta using QCD factorization. In the large $x_F$ region, leading contributions to the asymmetries are naturally produced by twist-3 parton correlation functions that couple quark fields and gluon field strengths. With a simple model for these matrix elements, leading-order asymmetries calculated from QCD are consistent with data on pion production from Fermilab, and can be used to predict single-spin asymmetries at RHIC. We argue that our perturbative calculation for the asymmetries is relevant to…
We study single-spin asymmetries in semi-inclusive deep inelastic scattering with transversely polarized target. Based on the QCD factorization approach, we consider Sivers and Collins contributions to the asymmetries. We fit simple parameterizations for the Sivers and Collins functions to the recent HERMES data, and compare to results from COMPASS. Using the fitted parameterizations for the Sivers functions, we predict the single transverse spin asymmetries for various processes in $pp$ collisions at RHIC, including the Drell-Yan process and angular correlations in dijet and jet-plus-photon p…
We analyze longitudinal beam and target single-spin asymmetries in semi-inclusive deep inelastic scattering and in jet deep inelastic scattering, including all possible twist-3 contributions as well as quark mass corrections. We take into account the path-ordered exponential in the soft correlators and show that it leads to the introduction of a new distribution and a new fragmentation function contributing to the asymmetries.
In a perturbative QCD approach, with inclusion of spin and transverse momentum effects, experimental data on azimuthal asymmetries observed in polarized semi-inclusive deeply inelastic scattering and e+ e- annihilations can be used to determine the Sivers, transversity and Collins soft functions. By using these functions, within the same scheme, we predict p(transv. polarized) p -> h + X single spin asymmetries in remarkable agreement with RHIC experimental data.
We study the single longitudinal-spin asymmetries in lepton-pair production with large transverse-momentum at RHIC and J-PARC experiments. The asymmetries in the azimuthal angular distribution of a lepton can arise from an absorptive part of production amplitudes. We revisit the one-loop calculation for the absorptive part of production amplitudes in perturbative QCD, and show that the asymmetries can be sizable at RHIC and J-PARC. Measurement of the asymmetries would test the one-loop prediction for the scattering phase of this process, and provide support for a study of the single transverse…
We give a short overview of the phenomenology of azimuthal and transverse single spin asymmetries in (un)polarized high-energy hadronic collisions. We briefly summarize a transverse momentum dependent, generalized parton model approach to these polarization phenomena, and discuss some of its applications. Finally, open points and future developments will be outlined.
The azimuthal single target-spin asymmetries for pi^{+} production in semi-inclusive deep inelastic scattering of leptons off longitudinally polarized protons are evaluated using two main approaches available in the literature. It is shown that the approximation where the twist-2 transverse quark spin distribution in the longitudinally polarized nucleon is small enough to be neglected leads to a consistent description of all existing asymmetries observed by the HERMES experiment.
Compact analytical formulae for QED radiative corrections in the processes of elastic $e-p$ scattering are obtained in the case when kinematic variables are reconstructed from the recoil proton momentum measured. Numerical analysis is presented under kinematic conditions of current experiments at JLab.
The polarized antiquark distributions in the proton can be measured by studying spin asymmetries in vector boson production in longitudinally polarized proton-proton collisions. The STAR and PHENIX experiments at BNL RHIC have reported first observations of single spin asymmetries in $W^\pm$-production most recently. We compute the QCD corrections to single and double spin asymmetries, taking account of the leptonic decay of the $W^\pm$ boson and of restrictions on the kinematical acceptance of the detectors. The QCD corrections have only a small impact on the asymmetries, such that a reliable…
We study some New Physics effects on the hadronic decays of the Top quark, like t-> b bbar c, and on a forward-backward-like CP even asymmetry A_t constructed in such a way that it is zero in the SM. We find that an anomalous right-handed contribution of the effective tbW vertex may induce an asymmetry A_t of the order of 20 %. A light W' boson with pure right handed couplings tdW' may induce an asymmetry A_t of the same order of magnitude.
We analyze the longitudinal-transverse double-spin asymmetry in lepton-nucleon collisions where a single hadron is detected in the final state, i.e., $\vec{\ell}\,N^\uparrow \rightarrow h\,X$. This is a subleading-twist observable in collinear factorization, and we look at twist-3 effects in both the transversely polarized nucleon and the unpolarized outgoing hadron. Results are anticipated for this asymmetry from both HERMES and Jefferson Lab Hall A, and it could be measured as well at COMPASS and a future Electron-Ion Collider. We also perform a numerical study of the distribution term, whic…
Predictions are made for azimuthal asymmetries in pion and kaon production from SIDIS off a longitudinally polarized deuterium target for HERMES kinematics, based on information on the 'Collins fragmentation function' from DELPHI data and on predictions for the transversity distribution function from non-perturbative calculations in the chiral quark-soliton model. There are no free parameters in the approach, which has been already successfully applied to explain the azimuthal asymmetries from SIDIS off polarized proton targets observed by HERMES and SMC.
We consider the single-spin azimuthal asymmetries recently measured at the HERMES experiment for charged pions produced in semi-inclusive deep inelastic scattering of leptons off longitudinally polarized protons. Guided by the experimental results and assuming a vanishing twist-2 transverse quark spin distribution in the longitudinally polarized nucleon, denoted as ``reduced twist-3 approximation'', a self-consistent description of the observed single-spin asymmetries is obtained. In addition, predictions are given for the z dependence of the single target-spin asymmetry.
We study neutralino production at the linear collider with the subsequent two-body decays ~chi^0_i -> ~chi^0_n Z^0 and Z^0 -> l^+ l^-, with l=e, mu, tau, or Z^0 -> q q- with q=c,b. We show that transverse electron and positron beam polarizations allow the definition of unique CP observables. These are azimuthal asymmetries in the distributions of the final leptons or quarks. We calculate these CP asymmetries and the cross sections in the Minimal Supersymmetric Standard Model with complex higgsino and gaugino parameters mu and M_1. For final quark pairs, we find CP asymmetries as large as 30%. …
The single spin asymmetries for a longitudinally polarized lepton beam or a longitudinally polarized nucleon target in semi-inclusive deep-inelastic scattering are twist-3 observables. We study these asymmetries in a simple diquark spectator model of the nucleon. Analogous to the case of transverse target polarization, non-vanishing asymmetries are generated by gluon exchange between the struck quark and the target system. It is pointed out that the coupling of the virtual photon to the diquark is needed in order to preserve electromagnetic gauge invariance at the twist-3 level. The calculatio…
The role of intrinsic transverse momentum both in unpolarized and polarized processes is discussed. We consider inclusive cross sections for pion production in hadronic collisions and for Drell-Yan processes; the results are compared with available experimental data in several different kinematical situations. We reanalyze transverse single spin asymmetries (SSA) observed in inclusive pion production, p(transv. polarized) p --> pion + X, in terms of Sivers effect and show how it can be disentangled in polarized Drell-Yan processes by suitably integrating over some final configurations. Estimat…
We show that the polarization of hyperons observed in high energy collisions using unpolarized hadron beams and unpolarized nucleon or nuclear targets is closely related to the left-right asymmetries observed in single spin inclusive hadron production processes. The relationship is most obvious for the production of the hyperons which have only one common valence quark with the projectile. Further implications of the existence of large polarization for hyperon which has two valence quarks in common with the projectile and their consequences are discussed. A comparison with the available data i…
We present a generalized QCD factorization scheme for the high energy inclusive polarized process, (A, S_A) + (B, S_B) -> C + X, including all intrinsic partonic motions. This introduces many non-trivial azimuthal phases and several new spin and k_T dependent soft functions. The formal expressions for single and double spin asymmetries are discussed. Numerical results for A_N[p(transv. polarized) p -> pi + X] are presented.
We analyze patterns from CP-violating new physics (NP) in hadronic and semileptonic rare charm $\vert Δc \vert=\vert Δu\vert=1$ transitions. Observation of direct CP-violation in hadronic decays, as in $ΔA_{\text{CP}}$, provides opportunities for $c \to u \,\ell^+ \ell^-$, $\ell=e,μ$ transitions, and vice versa. For the concrete case of flavorful, anomaly-free $Z^\prime$-models a NP-interpretation of $ΔA_{\text{CP}}$ suggests measurable CP-asymmetries in semileptonic decays such as $D \to π\, \ell^+ \ell^-$ or $D \to ππ\, \ell^+ \ell^-$. Conversely, an observation of CP-violation in $c \to u\,…
Using a generalized parton model approach including spin and intrinsic parton motion effects, and assuming the validity of factorization for large p_T jet production in hadronic collisions, we study the azimuthal distribution around the jet axis of leading pions, produced in the jet fragmentation process. We identify the observable leading-twist azimuthal asymmetries for the unpolarized and single-polarized case related to both quark and gluon-originated jets. We account for all physically allowed combinations of the transverse momentum dependent (TMD) parton distribution and fragmentation fun…
We review recent advances in the theory of strong-interaction effects and final-state interactions in hadronic weak decays of heavy mesons. In the heavy-quark limit, the amplitudes for most nonleptonic, two-body B decays can be calculated from first principles and expressed in terms of semileptonic form factors and light-cone distribution amplitudes. We summarize the main features of this novel QCD factorization and discuss its phenomenological applications to B->D^(*)+L decays (with L a light meson), and to the rare charmless decays B->pi+K and B->pi+pi.
Using a generalized parton model approach including spin and intrinsic parton motion effects, and assuming the validity of factorization for large-pT jet production in hadronic collisions, we study the azimuthal distribution around the jet axis of leading unpolarized or (pseudo)scalar hadrons, namely pions, produced in the jet fragmentation process. We identify the observable leading-twist azimuthal asymmetries for the unpolarized and single-polarized case related to quark and gluon-originated jets. We account for all physically allowed combinations of the transverse momentum dependent (TMD) p…
The distribution of hadrons produced in deeply inelastic electron-proton collisions depends on the azimuthal angle between lepton scattering plane and hadron production plane in the photon-proton centre-of-mass frame. In addition to the well known up-down asymmetry induced by the azimuthal dependence of the Born level subprocess, there is also a non-vanishing left-right asymmetry, provided the incoming electron is polarized. This asymmetry is time-reversal-odd and induced by absorptive corrections to the Born level process. We investigate the numerical magnitude of azimuthal asymmetries in sem…
We argue that weighted azimuthal single spin asymmetries in back-to-back jet or pion production in polarized proton-proton scattering can be written as convolutions of universal distribution and fragmentation functions with gluonic pole cross sections as hard functions. Gluonic pole cross sections are gauge-invariant weighted sums of Feynman diagrams. The weight factors are a direct consequence of the (diagram-dependence of) gauge links. The best known consequence of the gauge links is the generation of the Sivers effect that is a source for single-spin asymmetries. Moreover, due to the depend…
Predictions are made for single spin azimuthal asymmetries due to the Collins effect in pion production from semi-inclusive deeply inelastic scattering off transversely and longitudinally polarized targets for the HERMES and COMPASS experiments. The x-dependence of the asymmetries is evaluated using the parton distribution functions from the chiral quark-soliton model. The overall normalization of the predicted asymmetries is determined by the information on the Collins fragmentation function extracted from previous HERMES data on azimuthal asymmetries from a longitudinally polarized target. T…
A dispersive method to study CP asymmetries in hadronic multi-body $B$ decays
Universität Bonn（波恩大学）；Universidad Complutense de Madrid（马德里康普顿斯大学）；Forschungszentrum Jülich（于利希研究中心）；Universidade Estadual de Campinas（坎皮纳斯州立大学）；Universität Siegen（锡根大学）
We calculate the double-spin asymmetries $A_{\mathrm{LL}}$ for the processes $\ell N\to h X$ and $\ell N\to {\mathrm{jet}}\, X$ at next-to-leading order accuracy in perturbative QCD. We compare our theoretical results for $A_{\mathrm{LL}}$ to data from the SLAC E155 experiment, finding only partially satisfactory agreement. We conclude that measurements of $A_{\mathrm{LL}}$ and the relevant polarized and unpolarized cross sections should be performed at the present-day fixed-target lepton scattering experiments, as well as at a future electron ion collider, in order to verify our understanding…
The longitudinally polarized gluon density is probed sensitively in hard collisions of polarized protons under the condition that the dominant dynamics are perturbative and of leading twist origin. First data have recently been presented by Phenix on the double-spin asymmetry A_{LL}^{pi} for pi^0 production at moderate transverse momentum p_\perp \simeq 1 - 4 GeV and central rapidity. By means of a systematic investigation of the relevant degrees of freedom we show that the perturbative QCD framework at leading power in p_\perp produces an asymmetry that is basically positive definite in this …
We show that measurements of single-spin asymmetries (SSAs) in charged current weak interaction processes such as deep inelastic neutrino scattering on a polarized target and inclusive $W$ production in polarized hadron-hadron collisions discriminate between the two fundamental QCD mechanisms (the Sivers and Collins effects) which have been proposed to explain such time-reversal-odd asymmetries. It has recently been shown that QCD final-state interactions due to gluon exchange between the struck quark and the proton spectators in semi-inclusive deep inelastic lepton scattering will produce non…
We review what is currently known about the transverse spin structure of hadrons, in particular from observables that can be analyzed within a collinear framework. These effects have been around for 40 years and represent a critical test of perturbative QCD. We look at both proton-proton and lepton-nucleon collisions for various final states. While the main focus is on transverse single-spin asymmetries, we also discuss how longitudinal-transverse double-spin asymmetries offer a complimentary, yet equally important, source of information on the quark-gluon content of hadrons. We also summarize…
We propose a theoretical framework for analyzing two-body nonleptonic $D$ meson decays, based on the factorization of short-distance (long-distance) dynamics into Wilson coefficients (hadronic matrix elements of four-fermion operators). The parametrization of hadronic matrix elements in terms of several nonperturbative quantities is demonstrated for the $D\to PP$ decays, $P$ denoting a pseudoscalar meson. We consider the evolution of Wilson coefficients with energy release in individual decay modes, and the Glauber strong phase associated with the pion in nonfactorizable annihilation amplitude…
We study implications of a recent observation of non-leptonic $B^+_c\to D^0 K^+$ decay and a bound on $B^+_c\to D^0 π^+$ transition on CP-violating asymmetries in $B_c$ decays. In the U-spin symmetry limit, we derive a relation between the CP-asymmetries in the $B^+_c\to D^0 K^+$ and $B^+_c\to D^0 π^+$ channels and the corresponding branching ratios. We also derive several relations between non-leptonic $B_c$ decays into the final states with $D$ mesons in the flavor $SU(3)_F$ limit. We point out that a combined study of $SU(3)_F$ amplitudes in these decays can be used to constrain the angle $…
We calculate the double-spin transverse asymmetries for the Drell-Yan lepton pair production in p-p and p-anti p collisions. We assume the transverse and the longitudinal polarization densities to be equal at a very small scale, as it is suggested by confinement model results. Using a global fit for the longitudinal distributions, we find transverse asymmetries of order of 10^-2 at most, in the accessible kinematic regions.
A comprehensive collection of results on longitudinal double-spin asymmetries is presented for charged pions and kaons produced in semi-inclusive deep-inelastic scattering of electrons and positrons on the proton and deuteron, based on the full HERMES data set. The dependence of the asymmetries on hadron transverse momentum and azimuthal angle extends the sensitivity to the flavor structure of the nucleon beyond the distribution functions accessible in the collinear framework. No strong dependence on those variables is observed. In addition, the hadron charge-difference asymmetry is presented,…
We analyze the dependence of CP-odd asymmetries on longitudinally polarized e+ and e- beams in neutralino production and subsequent leptonic two-body decays. We give numerical examples of the asymmetries and of the cross sections in the Minimal Supersymmetric Standard Model with complex parameters mu, M_1 and A_{tau} for a collider with sqrt{s}=500 GeV. We show that longitudinally polarized electron and positron beams can enhance considerably both the asymmetries and the cross sections.
Polarized electron-deuteron DIS with spectator proton tagging offers a way of measuring the neutron spin structure functions with maximal theoretical control of nuclear effects. We calculate the nuclear structure factors in the longitudinal double-spin asymmetries using methods of light-front nuclear structure. A unique feature of the spin-1 system is that spin asymmetries can be formed either relative to the cross section in all three spin states ($λ_d = \pm 1, 0$) or in the two maximum-spin states only ($\pm 1$, involving tensor polarization). We find that the two-state deuteron spin asymmet…
We consider theoretical background for experimental measurements of single-spin asymmetries. We stress the non-perturbative QCD aspects of observed asymmetries in hadronic reactions.
We study the azimuthal asymmetries in proton-proton Drell-Yan processes with one incident proton being transversely or longitudinally polarized. We consider particularly the asymmetries contributed by the leading-twist chiral-odd quark distributions. We analyze the asymmetries with $\sin(2ϕ+ϕ_S)$ and $\sin(2ϕ-ϕ_S)$ modulations in transverse single polarized $p^\uparrow p$ Drell-Yan and $\sin2ϕ$ asymmetries in longitudinal single polarized $p^\rightarrow p$ Drell-Yan at RHIC, J-PARC, E906 (Fermi Lab) and NICA (JINR). We show that the measurements of the asymmetries in those facilities can provi…
Spin azimuthal asymmetries in pion electro-production in deep inelastic scattering off longitudinally polarized protons, measured by HERMES, are well reproduced theoretically with no adjustable parameters. Predictions for azimuthal asymmetries for a longitudinally polarized deuteron target are given. The z-dependence of the Collins fragmentation function is extracted. The first information on e(x) is extracted from CLAS A_LU asymmetry.
In order to illustrate the capabilities of COMPASS using a hadronic beam, I review some of the azimuthal asymmetries in hadronic collisions, that allow for the extraction of transversity, Sivers and Boer-Mulders functions, necessary to explore the partonic spin structure of the nucleon. I also report on some Monte Carlo simulations of such asymmetries for the production of Drell-Yan lepton pairs from the collision of high-energy pions on a transversely polarized proton target.
Using the recent experimental data on the left right asymmetry in fragmentation of transversely polarized quarks and the theoretical calculation of the proton transversity distribution in the effective chiral quark soliton model we explain the azimuthal asymmetries in semi-inclusive hadron production on longitudinal (HERMES) and transversely (SMC) polarized targets with no free parameters. On this basis we state that the proton transversity distribution could be successfully measured in future DIS experiments with longitudinally polarized target.
We present studies of double longitudinal spin asymmetries in semi-inclusive deep inelastic scattering using a new dedicated Monte Carlo generator, which includes quark intrinsic transverse momentum within the generalized parton model based on the fully differential cross section for the process. Additionally, we apply Bessel-weighting to the simulated events to extract transverse momentum dependent parton distribution functions and also discuss possible uncertainties due to kinematic correlation effects.
Partonic intrinsic transverse momentum can be essential for the explanation of large single spin asymmetries in hadronic reactions in the framework of perturbative QCD. The status of an ongoing program investigating in a consistent way the role of intrinsic transverse momentum both in unpolarized and polarized processes is discussed. We compute inclusive cross sections for hadron and photon production in hadronic collisions and for Drell-Yan processes; the results are compared with available experimental data in several different kinematical situations.
The high energy and large p_T inclusive polarized process, (A, S_A) + (B, S_B) --> C + X, is considered under the assumption of a generalized QCD factorization scheme. For the first time all transverse motions, of partons in hadrons and of hadrons in fragmenting partons, are explicitly taken into account; the elementary interactions are computed at leading order with noncollinear exact kinematics, which introduces many phases in the expressions of their helicity amplitudes. Several new spin and k_T dependent soft functions appear and contribute to the cross sections and to spin asymmetries; we…
Recently, the RHICf Collaboration measured the transverse single-spin asymmetries of the very forward neutral pion in polarized $p+p$ collisions at $\sqrt{s}=510$ GeV, produced at large pseudorapidity ($η\gtrsim 6$). The data show large asymmetries both in longitudinal momentum fraction $x_F$ and transverse momentum $p_T$ at $p_T<1\,\mathrm{GeV}/c$. Employing baryonic triple Regge exchanges, we describe the complete RHICf data for the first time and show that the neutral pion production at low $p_T$ can be interpreted as a diffractive one.
We review the theoretical status of b to s hadronic penguin decays in the Standard Model and beyond. We summarize the main theoretical tools to compute Branching Ratios and CP asymmetries for b to s penguin dominated nonleptonic decays, and discuss the theoretical uncertainties in the prediction of time-dependent CP asymmetries in this processes. We consider general aspects of b to s transitions beyond the Standard Model. Then we present detailed predictions in supersymmetric models with new sources of flavor and CP violation.
A number of recent determinations of $m_s$ using hadronic $τ$ decay data involve inclusive analyses based on the so-called $(k,0)$ spectral weights. We show here that the OPE representations of the longitudinal contributions appearing in these analyses, which are already known to be poorly converging, have in addition an unphysical $k$ dependence which produces a significant unphysical decrease in $m_s$ with increasing $k$. We also show how, using additional sum rule constraints, the decay constants of the excited resonances in the strange scalar and pseudoscalar channels may be determined, al…
We study the two-body hadronic $D\to PV$ decays, where $P$ ($V$) denotes a pseudoscalar (vector) meson, in the factorization-assisted topological-amplitude approach proposed in our previous work. This approach is based on the factorization of short-distance and long-distance dynamics into Wilson coefficients and hadronic matrix elements of four-fermion operators, respectively, with the latter being parametrized in terms of several nonperturbative quantities. We further take into account the $ρ$-$ω$ mixing effect, which improves the global fit to the branching ratios involving the $ρ^0$ and $ω$…
We propose a theoretical framework for analyzing three-body hadronic $B$ meson decays based on the perturbative QCD approach. The crucial nonperturbative input is a two-hadron distribution amplitude for final states, whose involved time-like form factor and rescattering phase are fit to relevant experimental data. Together with the short-distance strong phase from the $b$-quark decay kernel, we are able to make predictions for direct CP asymmetries in, for example, the $B^\pm \to π^+ π^- π^\pm$ and $π^+π^-K^\pm$ modes, which are consistent with the LHCb data in various localized regions of pha…
The electromagnetic and the muonic longitudinal profile at production enclosure important information about the primary particle and the hadronic interactions that rule the shower development. In fact, these two profiles provide two different insights of the shower: the electromagnetic component gives a measurement of the energy and the strength of the neutral pion channel; while the muonic profile, being intimately related with the charged mesons decays, can be used as a direct probe for the high energy hadronic interactions. In this work we explore the interplay between the electromagnetic a…
