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Journal articles on the topic 'Two-hadron asymmetries'

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Author: Grafiati
Published: 11 March 2023

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1

Bradamante, Franco. "Work on the Interplay Among h+, h− and Hadron Pair Transverse Spin Asymmetries in SIDIS." International Journal of Modern Physics: Conference Series 40 (January 2016): 1660039. http://dx.doi.org/10.1142/s2010194516600399.

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In the fragmentation of a transversely polarized quark a left-right asymmetry, the Collins asymmetry, is expected for each hadron produced in the process [Formula: see text]. Similarly, an asymmetry is also expected for the hadron pair, the dihadron asymmetry. Both asymmetries have been measured to be different from zero on transversely polarised proton targets and have allowed for first extractions of the transversity distributions. From the high statistics COMPASS data we have further investigated these asymmetries getting strong indications that the two mechanisms are driven by a common physical process.
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2

Geng, C. Q., and Y. K. Hsiao. "Search for direct CP violation in baryonic b-hadron decays." Modern Physics Letters A 31, no. 23 (July 19, 2016): 1630021. http://dx.doi.org/10.1142/s0217732316300214.

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We first review direct CP violation in the three-body baryonic [Formula: see text] decays of [Formula: see text] with [Formula: see text] and [Formula: see text]. We then present our recent results of the direct CP violating asymmetries in the two-body [Formula: see text] decays of [Formula: see text] as well as the three-body [Formula: see text]. In particular, we emphasize that the large direct CP violating asymmetries in [Formula: see text] and [Formula: see text] are both around 20%, which are accessible to the b-hadron experiments.
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3

Yang, Weihua. "Azimuthal asymmetries from 𝜃 vacuum." International Journal of Modern Physics A 34, no. 18 (June 28, 2019): 1950095. http://dx.doi.org/10.1142/s0217751x19500957.

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We present the complete azimuthal asymmetries at leading twist in terms of fragmentation functions in dihadron production semi-inclusive electron–positron annihilation process. When the nontrivial [Formula: see text] vacuum is taken into consideration, the parity symmetry of quantum chromodynamics is violated. As a consequence of the [Formula: see text] [Formula: see text]-odd effects, [Formula: see text]-odd fragmentation functions would contribute to the azimuthal asymmetries. Azimuthal asymmetry coming from two interference terms with opposite signs vanishes when sum over many events. This symmetry only survives on the event-by-event basis. Azimuthal asymmetry coming from two interference terms with same signs survives and can be measured to extract the [Formula: see text]-odd fragmentation functions. We also present the hadron polarizations.
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4

Braun, Christopher. "COMPASS results on transverse spin asymmetries in identified two-hadron production in SIDIS." Physics of Particles and Nuclei 45, no. 1 (January 2014): 132–34. http://dx.doi.org/10.1134/s1063779614010158.

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5

WARBURTON, ANDREAS. "BRANCHING FRACTIONS AND CP ASYMMETRIES IN TWO-BODY NONLEPTONIC CHARMLESS b-HADRON DECAYS." International Journal of Modern Physics A 20, no. 15 (June 20, 2005): 3554–58. http://dx.doi.org/10.1142/s0217751x05026960.

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Relative branching fractions of [Formula: see text] decays (where h, h′ = K or π) and the direct CP asymmetry [Formula: see text] in the [Formula: see text] mode are measured with 179 ± 11 pb -1 of data collected at [Formula: see text] using the CDF II detector at the Fermilab Tevatron [Formula: see text] collider. The first branching-fraction measurement of a [Formula: see text] meson to two pseudoscalars, [Formula: see text], and a search for the baryon mode [Formula: see text] are also presented, in addition to branching-fraction limits on the rare channels [Formula: see text], [Formula: see text], and [Formula: see text].
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6

Guan, Yinghui. "Measurement of Collins Asymmetries in Inclusive Production of Charged Pion Pairs at BESIII." International Journal of Modern Physics: Conference Series 40 (January 2016): 1660033. http://dx.doi.org/10.1142/s2010194516600338.

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We present the preliminary results of the measurement of the azimuthal asymmetries of two charged pions in the inclusive process [Formula: see text] in the BESIII experiment. These asymmetries are attributed to the so-called Collins fragmentation function, which depict the behavior of a hadron produced from a transversely polarized quark. This spin-dependent function is an important input for the global analysis of extracting the transversity inside the nucleon. In addition, by comparison with the measured asymmetries at Belle, this measurement provides the first data to explore the [Formula: see text] evolution of the spin-dependent fragmentation function. This work is performed based on about 62[Formula: see text][Formula: see text] data collected with the BESIII detector at BEPCII at [Formula: see text]=3.65[Formula: see text]GeV.
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7

Sun, Yi, Xian-Fu Wang, and Dao-Neng Gao. "CP mixed property of the Higgs-like particle in the decay channel h→Z Z*→4l." International Journal of Modern Physics A 29, no. 15 (May 30, 2014): 1450086. http://dx.doi.org/10.1142/s0217751x14500869.

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Current experiments do not support, as ATLAS and CMS Collaborations at the Large Hadron Collider reported, that the Higgs-like resonance discovered in July 2012 is a pure CP-odd state. We examine a general hZZ vertex which contains CP-even and CP-odd couplings, by studying the process [Formula: see text] with l1, l2 = e or μ, to explore the CP mixed property of the Higgs-like particle. One momentum asymmetry and two angular asymmetries have been analyzed in order to reveal the difference from different CP-couplings. Our study shows that these asymmetries could be interesting observables in the future precise experiments.
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8

Boer, D., R. Jakob, and P. J. Mulders. "Leading asymmetries in two-hadron production in e+e− annihilation at the Z pole." Physics Letters B 424, no. 1-2 (April 1998): 143–51. http://dx.doi.org/10.1016/s0370-2693(98)00136-1.

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9

BRODSKY, STANLEY J. "HADRON SPIN DYNAMICS." International Journal of Modern Physics A 18, no. 08 (March 30, 2003): 1531–50. http://dx.doi.org/10.1142/s0217751x03015027.

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Spin effects in exclusive and inclusive reactions provide an essential new dimension for testing QCD and unraveling hadron structure. Remarkable new experiments from SLAC, HERMES (DESY), and Jefferson Lab present many challenges to theory, including measurements at HERMES and SMC of the single spin asymmetries in ep → e′ π X where the proton is polarized normal to the scattering plane. This type of single spin asymmetry may be due to the effects of rescattering of the outgoing quark on the spectators of the target proton, an effect usually neglected in conventional QCD analyses. Many aspects of spin, such as single-spin asymmetries and baryon magnetic moments are sensitive to the dynamics of hadrons at the amplitude level, rather than probability distributions. I will illustrate the novel features of spin dynamics for relativistic systems by examining the explicit form of the light-front wavefunctions for the two-particle Fock state of the electron in QED, thus connecting the Schwinger anomalous magnetic moment to the spin and orbital momentum carried by its Fock state constituents and providing a transparent basis for understanding the structure of relativistic composite systems and their matrix elements in hadronic physics. I also present a survey of outstanding spin puzzles in QCD, particularly ANN in elastic pp scattering, the J/ψ → ρπ puzzle, and J/ψ polarization at the Tevatron.
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10

Cowan, Ray F. "Studies of Inclusive Hadron Production at BABAR." International Journal of Modern Physics: Conference Series 37 (January 2015): 1560065. http://dx.doi.org/10.1142/s2010194515600654.

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The clean environment of the e+e- collisions provided by the B-factory PEP-II and the high performances of the BABAR detector allow for precise measurements of the properties of inclusive hadron production. We present recent results obtained using the full data sample of nearly 500 fb-1 on measurements of the inclusive light hadrons momentum spectra, and on anti-deuteron production from decays of bottomonium states, and from continuum e+e- annihilation. We also present a measurement of the azimuthal asymmetries induced by the Collins effect in inclusive production of pion pairs in e+e- → ππX annihilation, where the two pions are produced in opposite hemispheres.
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11

Arhrib, Abdesslam, Adil Jueid, and Stefano Moretti. "Searching for heavy charged Higgs bosons through top quark polarization." International Journal of Modern Physics A 35, no. 15n16 (June 4, 2020): 2041011. http://dx.doi.org/10.1142/s0217751x20410110.

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We study the production of a heavy charged Higgs boson at the Large Hadron Collider (LHC) in [Formula: see text] within a 2-Higgs Doublet Model (2HDM). The chiral structure of the [Formula: see text] coupling can trigger a particular spin state of the top quark produced in the decay of a charged Higgs boson and, therefore, is sensitive to the underlying mechanism of the Electroweak Symmetry Breaking (EWSB). Taking two benchmark models (2HDM type-I and 2HDM type-Y) as an example, we show that inclusive rates, differential distributions and forward–backward asymmetries of the top quark’s decay products can be used to search for heavy charged Higgs bosons and also as model discriminators.
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12

Brodsky, Stanley J. "Physics Opportunities at a Photon–Photon Collider." International Journal of Modern Physics A 18, no. 16 (June 30, 2003): 2871–92. http://dx.doi.org/10.1142/s0217751x03016343.

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The advent of back-scattered laser beams for e±e-colliders will allow detailed studies of a large array of high energy γγ and γe collision processes with polarized beams. These include tests of electroweak theory in photon-photon annihilation such as γγ → W+W-, γγ → Higgs bosons, and higher-order loop processes, such as γγ → γγ, Zγ, H0Z0and ZZ. Methods for measuring the anomalous magnetic and quadrupole moments of the W and Z gauge bosons to high precision in polarized electron-photon and photon-photon collisions are discussed. Since each photon can be resolved into a W+W-pair, high energy photon-photon collisions can also provide a remarkably background-free laboratory for studying WW collisions and annihilation. I also review high energy γγ and eγ tests of quantum chromodynamics, including the production of two gluon jets in photon-photon collisions, deeply virtual Compton scattering on a photon target, and leading-twist single-spin asymmetries for a photon polarized normal to a production plane. Exclusive hadron production processes in photon-photon collisions provide important tests of QCD at the amplitude level, particularly as measures of hadron distribution amplitudes which are also important for the analysis of exclusive semi-leptonic and two-body hadronic B-decays.
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13

Gonsalves, Richard J., and C. F. Wai. "Chromoelectroweak interference and parity-violating asymmetries in the production of an electroweak boson + two jets in hadron collisions." Physical Review D 49, no. 1 (January 1, 1994): 190–218. http://dx.doi.org/10.1103/physrevd.49.190.

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14

Gonsalves, Richard J., and C. F. Wai. "Erratum: Chromoelectroweak interference and parity-violating asymmetries in the production of an electroweak boson + two jets in hadron collisions." Physical Review D 51, no. 3 (February 1, 1995): 1428. http://dx.doi.org/10.1103/physrevd.51.1428.

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15

BRADAMANTE, FRANCO. "TRANSVERSE SPIN AND TRANSVERSE MOMENTUM EFFECTS AT COMPASS." Modern Physics Letters A 24, no. 35n37 (December 7, 2009): 3015–24. http://dx.doi.org/10.1142/s0217732309001224.

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The study of transverse spin and transverse momentum effects is part of the scientific program of COMPASS, a fixed target experiment at the CERN SPS. For these studies, a 160 GeV/c momentum muon beam is scattered on a transversely polarized nucleon target, and the scattered muon and the forward going hadrons produced in DIS processes are reconstructed and identified in a magnetic spectrometer. The measurements have been performed on a deuteron target in 2002, 2003 and 2004, and on a proton target in 2007. The main results obtained measuring single spin asymmetries are reviewed, with particular emphasis on the most recent proton measurements. After two years of spectroscopy measurements with hadron beams, in 2008 and 2009, the Collaboration will resume measurements with the muon beam and a transversely polarized target in 2010.
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16

Drachenberg, J. L. "Exploring nucleon structure and hadronization with dihadrons and hadrons in jets at STAR." Journal of Physics: Conference Series 1643, no. 1 (December 1, 2020): 012188. http://dx.doi.org/10.1088/1742-6596/1643/1/012188.

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Abstract Over the last decade, theoretical and experimental engagement of transverse-spin phenomena has unlocked tantalizing opportunities for new insights into nucleon structure and hadronization. Observables such as hadrons in jets and dihadron correlations from polarized proton collisions provide access to the transversity distribution function at a range of x complementary to existing semi-inclusive deep inelastic scattering (SIDIS) experiments but at a much higher range of Q 2. Moreover, these two observables give access through two different factorization frameworks–transverse-momentum-dependent (TMD) and collinear–enabling a unique path to address questions concerning factorization-breaking and the universality of TMD functions. Data collected by STAR have revealed the first observations of transverse single-spin asymmetries in the azimuthal distributions of dihadron correlations and hadrons within jets from polarized proton collisions at both s = 500 GeV and 200 GeV. The STAR 200 GeV dihadron data have recently been included in global analyses that for the first time include SIDIS, e + e −, and p + p data to extract the transversity distribution. The STAR hadron-in-jet data provide a unique opportunity to illuminate longstanding questions: Do factorization and universality extend to the TMD picture in proton-proton collisions, e.g. through the Collins mechanism? How do TMD functions evolve with changing kinematics? The STAR dihadron and hadron-in-jet data will be presented and discussed in context with the recent global analyses and model calculations.
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17

Borisyuk, D., and A. Kobushkin. "Two-Photon Exchange in Elastic Electron Scattering on Hadronic Systems." Ukrainian Journal of Physics 66, no. 1 (January 29, 2021): 3. http://dx.doi.org/10.15407/ujpe66.1.3.

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In the present review, we discuss different aspects of the two-photon exchange (TPE) physics in elastic ep scattering at high Q2, as well as at low Q2. The imaginary part of the TPE amplitude gives rise to beam and target single-spin asymmetries. Different theoretical approaches to the calculation of these observables are considered. The real part of the TPE amplitude influences the unpolarized cross-section and double-spin observables and is, most likely, responsible for the discrepancy between two methods of measurements of the proton form factors. We review different methods of calculations of the TPE amplitudes in the framework of the “hadron” and “quark-gluon” approaches. We discuss the dispersion approach suitable for low and intermediate Q2, which includes elastic and inelastic intermediate hadronic states, as well as the connection of TPE with the proton radius puzzle. The present situation with direct experimental searches for the TPE amplitude in the e+p/e−p charge asymmetry is also discussed, as well as attempts to extract the TPE amplitudes from existing experimental data obtained by the Rosenbluth and double polarization techniques. The TPE physics in other processes such as elastic мp, e-nucleus, and еп scattering is also reviewed.
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18

Kohri, H. "Recent results of charged pion and kaon photoproduction on the proton at SPring-8/LEPS." EPJ Web of Conferences 241 (2020): 01010. http://dx.doi.org/10.1051/epjconf/202024101010.

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We carry out photoproduction experiments by using linearly polarized photon beams with energies of 1.5-3 GeV at SPring-8/LEPS. One of our physics motivations is to understand reaction mechanisms of hadron photoproduction. We study (1) y→p→ π-Δ++, (2) y→p→ π+n, (3) y→p→ K+Λ(K+Σ0), and (4) y→p→ π+Δ0 reactions which produce (1) uu, (2) dd, (3) ss, and (4) dd quark-antiquark pairs in the final state. Differential cross sections and photon beam asymmetries have been measured at forward meson angles of 0.6 < cos θcm <1. Precise comparison between the π-Δ++ and π+Δ0 reactions plays an important role in the study of nucleon resonances. It enables to distinguish between N* and Δ* by taking the cross section ratios of the two reactions. We have measured preliminary cross section ratios dσ(π+Δ0)/dσ(π-Δ++). The ratios are found to be close to 1/3, which is expected from the exchange of isospin=1 in the t channel, for 0.966< cos θcm <1 and all the photon energies. The ratios become larger than 1/3 and close to 1 for larger angles and higher energy regions. The larger ratios might be due to A resonances, giving the ratio 4/3, excited in the intermediate state
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19

Syromyatnikov, A. G. "On some features of possible torsion effects on observables at Hadron colliders." International Journal of Geometric Methods in Modern Physics 12, no. 10 (October 25, 2015): 1550080. http://dx.doi.org/10.1142/s0219887815500802.

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I give a geometrical description of conformal gauge gravitational theory (CGTG) from the viewpoint of symmetries and affine structure. In the frames of the CGTG incorporating gravitation with torsion space-time into Standard Model of electro-weak interaction (EWI) the multi-muon events produced at the Fermilab Tevatron collider were studied. The CGTG gives the value of the torsion pseudotrace–spinor (muon) universal coupling fT = 4.388 ⋅ 10-17 GF, and with limits from known experiments — torsion mass mT = 0.4700 ⋅ 10-7 eV or mT = 0.445 ⋅ 10-15 muon mass. So the value of the constant of effective four-fermions interaction fT/mT = 0.988, indeed may lead to multi-muon events production. The model of interaction of quantum oscillator with the tensor potential Wμν of traceless part of the torsion lead to 2 cm displacement of quark–lepton system as a whole in the magnetic field of collider in accordance with a significant sample of events related to [Formula: see text] production and decay in which at least one of the muon candidates is produced outside of the beam pipe of radius 1.5 cm. A traceless part of the torsion in CGTG does not vanish in the Newtonian limit of nonzero mass. Torsion gravity potential Wμν gives conservation of a special conformal current and may be produced in the condition of a spontaneous breaking of gauge symmetry where the gravitation mass MX defect is 1–3 Tev ⋅ c-2 or 10-13MX. This effect may be possible at known effects on top pair asymmetries at the Tevatron and LHC and takes place as the known energy dissipation above 3 TeV of the Galaxy gamma-ray and neutrino spectrum from two bubbles outside the Galaxy plane.
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20

Bravina, L., and E. Zabrodin. "Relaxation to equilibrium in relativistic heavy ion collisions." EPJ Web of Conferences 182 (2018): 02019. http://dx.doi.org/10.1051/epjconf/201818202019.

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Relaxation to equilibrium of hot and dense matter produced in central area of relativistic heavy ion collisions at energies ranging from several AGeV to hundreds AGeV is studied within two Monte Carlo transport models. The analysis was performed for three different areas: (i) fixed cubic cell with volume V = 125 fm3, (ii) fixed asymmetric cell with volume V = 4 x 4 x 1 = 16 fm3, and (iii) expanding cell. In the last case the cell volume follows the growth of the area with uniformly distributed energy. To check whether or not the system is equilibrated, its hadron yields and their energy spectra are compared with those of the statistical model of ideal hadron gas. For all cells and for all collision energies it was found that the matter in the cell was approaching the equilibrium state. The higher the collision energy, the shorter the time of equilibration. The equilibration phase lasts about 10 - 20 fm/c, after that the matter becomes very dilute and the thermal contact between hadrons is lost. Equation of state is well fitted to linear dependence P/ɛ = a = c2s , where the square of the sonic velocity c2s increases from 0.12 at Elab = 11.6AGeV to 0.145 at Elab = 160AGeV. The characteristic kinks observed in the T - μB phase diagrams are linked to inelastic freeze-out in the expanding fireball.
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21

Fischer, Wolfram, and John M. Jowett. "Ion Colliders." Reviews of Accelerator Science and Technology 07 (January 2014): 49–76. http://dx.doi.org/10.1142/s1793626814300047.

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High energy ion colliders are large research tools in nuclear physics for studying the quark–gluon–plasma (QGP). The collision energy and high luminosity are important design and operational considerations. The experiments also expect flexibility with frequent changes in the collision energy, detector fields, and ion species. Ion species range from protons, including polarized protons in RHIC, to heavy nuclei like gold, lead, and uranium. Asymmetric collision combinations (such as protons against heavy ions) are also essential. For the creation, acceleration, and storage of bright intense ion beams, limits are set by space charge, charge change, and intrabeam scattering effects, as well as beam losses due to a variety of other phenomena. Currently, there are two operating ion colliders: the Relativistic Heavy Ion Collider (RHIC) at BNL and the Large Hadron Collider (LHC) at CERN.
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22

RADICI, MARCO, ALESSANDRO BACCHETTA, and A. COURTOY. "DETECTING CORRELATED DI-HADRON PAIRS: ABOUT THE EXTRACTION OF TRANSVERSITY AND BEYOND." International Journal of Modern Physics: Conference Series 25 (January 2014): 1460045. http://dx.doi.org/10.1142/s2010194514600453.

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We summarize the latest achievements about the extraction of the transversity parton distribution based on an analysis of pion-pair production in deep-inelastic scattering off transversely polarized targets in collinear factorization. Recently released data for proton and deuteron targets by HERMES and COMPASS allow for a flavor separation of the valence components of transversity. This extraction relies on di-hadron fragmentation functions. The latter have been taken from the first recent analysis of the semi-inclusive production of two pion pairs in back-to-back jets in e+e- annihilation. We also comment on the possibility of isolating new azimuthally asymmetric correlations of opposite pion pairs, which could arise when a fragmenting quark crosses parity-odd domains localized in Minkowski space-time and induced by the topologically nontrivial QCD background (the so-called θ vacuum).
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23

Nasteva, Irina. "Charmless b-hadron decays at LHCb." Suplemento de la Revista Mexicana de Física 3, no. 3 (June 8, 2022). http://dx.doi.org/10.31349/suplrevmexfis.3.0308062.

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Measurements of CP asymmetries in charmless two-body B-meson decays can provide stringent tests of the Standard Model. In multibody decays, short and long-distance dynamics along with a sizeable effective weak phase in the interference between tree and penguin amplitudes can lead to a rich structure of CP violation as a function of the phase space. We present here the latest studies of CP violation in charmless b-hadron decays, in particular those with baryons in the initial and final states.
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24

Matevosyan, Hrayr H., Aram Kotzinian, Elke-Caroline Aschenauer, Harut Avakian, and Anthony W. Thomas. "Predictions for Sivers single spin asymmetries in one- and two-hadron electroproduction at CLAS12 and EIC." Physical Review D 92, no. 5 (September 23, 2015). http://dx.doi.org/10.1103/physrevd.92.054028.

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25

Yang, Weihua. "Hadron pair production in semi-inclusive electron positron annihilation process at twist-4." European Physical Journal C 82, no. 8 (August 24, 2022). http://dx.doi.org/10.1140/epjc/s10052-022-10698-y.

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AbstractFragmentation functions are important quantities in describing the hadronization process in high energy reactions. They can induce various azimuthal modulations which can be measured to reveal correlations between transverse momenta and polarizations. Without introducing initial state uncertainties, electron positron annihilation process is known as an ideal process to investigate the fragmentation functions. In this paper, therefore, we calculate the hadron pair production in the semi-inclusive electron positron annihilation process $$e^+ + e^- \rightarrow h_1+h_2 + {\bar{q}} +X$$ e + + e - → h 1 + h 2 + q ¯ + X at twist-4 to study dihadron fragmentation functions. Here $${\bar{q}}$$ q ¯ denotes an antiquark that corresponds to a jet of hadrons in experiments. Together with single hadron fragmentation functions, dihadron fragmentation functions can provide additional ways to extract nucleon parton distribution functions from the semi-inclusive deeply inelastic scattering experiments with two detected final state hadrons. We calculate the differential cross section of the hadron pair production semi-inclusive electron positron annihilation process at twist-4 level. The calculation is carried out by using the collinear expansion method. We also calculate azimuthal asymmetries in terms of dihadron fragmentation functions. Contributions from four-quark correlator are also taken into account. Both the electromagnetic and weak interactions are considered in this paper.
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26

Agostini, Pedro, Tolga Altinoluk, and Néstor Armesto. "Effect of non-eikonal corrections on azimuthal asymmetries in the color glass condensate." European Physical Journal C 79, no. 9 (September 2019). http://dx.doi.org/10.1140/epjc/s10052-019-7315-1.

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Abstract We analyse the azimuthal structure of two gluon correlations in the color glass condensate including those effects that result from relaxing the shockwave approximation for the target. Working in the Glasma graph approach suitable for collisions between dilute systems, we compute numerically the azimuthal distributions and show that both even and odd harmonics appear. We study their dependence on model parameters, energy of the collision, pseudorapidity and transverse momentum of the produced particles, and length of the target. While the contribution from non-eikonal corrections vanishes with increasing collision energy and becomes negligible at the energies of the Large Hadron Collider, it is found to be sizeable up to top energies at the Relativistic Heavy Ion Collider.
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Adolph, Nico, Joachim Brod, and Gudrun Hiller. "Radiative three-body D-meson decays in and beyond the standard model." European Physical Journal C 81, no. 1 (January 2021). http://dx.doi.org/10.1140/epjc/s10052-021-08832-3.

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AbstractWe study radiative charm decays $$D \rightarrow P_1 P_2 \gamma $$ D → P 1 P 2 γ , $$P_{1,2}=\pi ,K$$ P 1 , 2 = π , K in QCD factorization at leading order and within heavy hadron chiral perturbation theory. Branching ratios including resonance contributions are around $$\sim 10^{-3}$$ ∼ 10 - 3 for the Cabibbo-favored modes into $$K \pi \gamma $$ K π γ and $$\sim 10^{-5}$$ ∼ 10 - 5 for the singly Cabibbo-suppressed modes into $$\pi ^+ \pi ^- \gamma , K^+ K^- \gamma $$ π + π - γ , K + K - γ , and thus in reach of the flavor factories BES III and Belle II. Dalitz plots and forward–backward asymmetries reveal significant differences between the two QCD frameworks; such observables are therefore ideally suited for a data-driven identification of relevant decay mechanisms in the standard-model dominated $$D \rightarrow K \pi \gamma $$ D → K π γ decays. This increases the potential to probe new physics with the $$D \rightarrow \pi ^+ \pi ^- \gamma $$ D → π + π - γ and $$D \rightarrow K^+ K^- \gamma $$ D → K + K - γ decays, which are sensitive to enhanced dipole operators. CP asymmetries are useful to test the SM and look for new physics in neutral $$|\Delta C|=1$$ | Δ C | = 1 transitions. Cuts in the Dalitz plot enhance the sensitivity to new physics due to the presence of both s- and t, u-channel intermediate resonances.
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28

Penalva, Neus, Eliecer Hernández, and Juan Nieves. "Visible energy and angular distributions of the charged particle from the τ −decay in $$ b\to c\tau \left(\mu {\overline{\nu}}_{\mu }{\nu}_{\tau },{\pi \nu}_{\tau },{\rho \nu}_{\tau}\right){\overline{\nu}}_{\tau } $$ reactions." Journal of High Energy Physics 2022, no. 4 (April 2022). http://dx.doi.org/10.1007/jhep04(2022)026.

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Abstract We study the d2Γd/(dωd cos θd), dΓd/d cos θd and dΓd/dEd distributions, which are defined in terms of the visible energy and polar angle of the charged particle from the τ −decay in $$ b\to c\tau \left(\mu {\overline{\nu}}_{\mu }{\nu}_{\tau },{\pi \nu}_{\tau },{\rho \nu}_{\tau}\right){\overline{\nu}}_{\tau } $$ b → cτ μ ν ¯ μ ν τ πν τ ρν τ ν ¯ τ reactions. These differential decay widths could be measured in the near future with certain precision. The first two contain information on the transverse tau-spin, tau-angular and tau-angular-spin asymmetries of the $$ {H}_b\to {H}_c\tau {\overline{\nu}}_{\tau } $$ H b → H c τ ν ¯ τ parent decay and, from a dynamical point of view, they are richer than the commonly used one, d2Γd/(dωdEd), since the latter only depends on the tau longitudinal polarization. We pay attention to the deviations with respect to the predictions of the standard model (SM) for these new observables, considering new physics (NP) operators constructed using both right- and left-handed neutrino fields, within an effective field-theory approach. We present results for $$ {\Lambda}_b\to {\Lambda}_c\tau \left(\mu {\overline{\nu}}_{\mu }{\nu}_{\tau },{\pi \nu}_{\tau },{\rho \nu}_{\tau}\right){\overline{\nu}}_{\tau } $$ Λ b → Λ c τ μ ν ¯ μ ν τ πν τ ρν τ ν ¯ τ and $$ \overline{B}\to {D}^{\left(\ast \right)}\tau \left(\mu {\overline{\nu}}_{\mu }{\nu}_{\tau },{\pi \nu}_{\tau },{\rho \nu}_{\tau}\right){\overline{\nu}}_{\tau } $$ B ¯ → D ∗ τ μ ν ¯ μ ν τ πν τ ρν τ ν ¯ τ sequential decays and discuss their use to disentangle between different NP models. In this respect, we show that dΓd/d cos θd, which should be measured with sufficiently good statistics, becomes quite useful, especially in the τ → πντ mode. The study carried out in this work could be of special relevance due to the recent LHCb measurement of the lepton flavor universality ratio $$ {\mathrm{\mathcal{R}}}_{\Lambda_c} $$ ℛ Λ c in agreement with the SM. The experiment identified the τ using its hadron decay into π−π+π−ντ, and this result for $$ {\mathrm{\mathcal{R}}}_{\Lambda_c} $$ ℛ Λ c , which is in conflict with the phenomenology from the b-meson sector, needs confirmation from other tau reconstruction channels.
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29

Papaefstathiou, Andreas, Tania Robens, and Gilberto Tetlalmatzi-Xolocotzi. "Triple Higgs boson production at the Large Hadron Collider with Two Real Singlet scalars." Journal of High Energy Physics 2021, no. 5 (May 2021). http://dx.doi.org/10.1007/jhep05(2021)193.

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Abstract We investigate the production of three Higgs bosons in the Two Real Singlet extension of the Standard Model, where the scalar sector is augmented by two additional real scalar fields which are singlets under the Standard Model gauge group. The model contains three neutral CP-even scalars, allowing for resonant production and asymmetric decay chains. We focus on the signature pp → h3→ h1h2→ h1h1h1, where we identify h3 as the heaviest scalar state, h2 as the second heaviest and the lightest, h1, as the Standard Model-like Higgs boson discovered by the Large Hadron Collider experiments. The dominant final state occurs when all three Higgs bosons decay to bottom-anti-bottom quark pairs, h1→$$ b\overline{b} $$ b b ¯ , leading to 6 b-jets. Taking into account all current theoretical and experimental constraints, we determine the discovery prospects for this channel in future runs of the Large Hadron Collider, as well as in the high-luminosity phase.
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30

Doršner, Ilja, Ajla Lejlić, and Shaikh Saad. "Asymmetric leptoquark pair production at LHC." Journal of High Energy Physics 2023, no. 3 (March 3, 2023). http://dx.doi.org/10.1007/jhep03(2023)025.

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Abstract We investigate asymmetric leptoquark pair production mechanism at the Large Hadron Collider to advocate its potential relevance to establish reliable constraints on the leptoquark parameter space and its ability to aid in correct identification of these attractive sources of new physics. The main feature of asymmetric pair production that genuinely distinguishes it from the usual leptoquark pair production is given by the fact that the two leptoquarks that are produced in proton-proton collisions through a t-channel lepton exchange are not charge conjugates of each other. Hence the proposed name of asymmetric leptoquark pair production for this type of process. We spell out prerequisite conditions for the asymmetric leptoquark pair production mechanism to be operational and enumerate all possible combinations of leptoquark multiplets that can potentially generate it. We finally reinterpret existing leptoquark pair production search results within several simple scalar leptoquark extensions of the Standard Model, assuming that the leptoquarks exclusively couple to either electrons or muons and the first generation quarks, to demonstrate proper inclusion of asymmetric pair production. We consequently present accurate parameter space constraints for the S1, S3, R2, S1+S3, and S1+R2 leptoquark scenarios.
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