DOCSLIB.ORG

Run Group E Jeopardy Update

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Run Group E Jeopardy Update Run Group E Jeopardy Update W. Armstrong,1 M. Arratia,2 W.K. Brooks, A. El Alaoui, H. Hakobyan, J. L´opez, T. Mineeva,3 R. Dupr´e,4 L. El Fassi,5 G. Gilfoyle,6 K. Hicks,7 M. Holtrop,8 K. Joo,9 G. Niculescu, I. Niculescu,10 O. Soto,11 and M. Wood12 1Argonne National Laboratory, Lemont IL, USA 2University of California, Riverside CA, USA, and Thomas Jefferson National Accelerator Facility, Newport News, VA 23606, USA 3Universidad T´ecnica Federico Santa Mar´ıa, Valpara´ıso, Chile 4Universit´eParis-Saclay, CNRS, IJCLab, 91405, Orsay, France 5Mississippi State University, Mississippi State MS, USA 6University of Richmond, Richmond VA, USA 7Ohio University, Athens OH, USA 8University of New Hampshire, Durham NH, USA 9University of Connecticut, Storrs CT, USA 10James Madison University, VA, USA 11INFN Frascati, Frascati, Italy 12Canisius College, Buffalo NY, USA (Dated: June 2020) Run Group E consists of Jefferson Lab experiment matics. This time is at the femtometer scale, and thus it E12-06-117 "Quark Propagation and Hadron Formation" can only be directly measured by the interaction within which was originally approved in 2006 and later given nuclei, which have dimensions of that same scale. We will the scientific rating of "A−" by PAC 36 in 2010[15]. also extract the interaction cross sections of a variety of The experiment will make use of nuclear targets to gain mesons and baryons and study the kinematic dependen- substantial new insights into the propagation of QCD cies needed to describe their formation mechanisms. color through strongly interacting systems. There are two essential thrusts of these studies. First, we seek to characterize the fundamental QCD subprocesses of color A. Advances in Theory and Phenomenology propagation and hadron formation in quark fragmenta- tion, extrapolating from observations with nuclear tar- Recently, members of our team completed an extrac- gets to the more general cases of proton targets or the tion of the color lifetime for light quarks from HERMES early universe[2]. Second, we seek to greatly expand our published data[4]. The method employed by Brooks and knowledge about the color structure of nuclei from these L´opez (BL) was to fit two observables simultaneously in a studies by using the struck quark as a colored probe of geometrical framework with realistic nuclear density dis- the medium. By studying the strength of the interac- tributions. The framework is not a dynamical model, but tion between the colored quark and the nuclear medium rather it makes a geometrical association between stages using the transport coefficientq ^, we gain quantitative of the hadronization process and experimental observ- understanding of the color structure of bound nucleons ables, with the outcome strongly constrained by the fixed via color charge form factors[7]. An extraction of theq ^ nuclear density distributions of the three heavier nuclei. transport coefficient was recently performed by members The first observable, transverse momentum broadening of our collaboration[4]. The same analysis will be car- 2 of charged pions ∆pT , was associated in the framework ried out on the data from our 12 GeV experiment, and with partonic multiple scattering over a period of time will measure the multivariate dependence ofq ^, promising corresponding to the color lifetime. The second observ- an enormous advance in our understanding of the color π able, the hadronic multiplicity ratio RM , was associated structure of nuclei. with interaction of formed hadrons within the nuclear medium. An excellent fit of the data was obtained for all three of the heavier nuclei (neon, krypton, and xenon) in I. PHYSICS GOALS AND NEW this simple physical picture with two fit parameters: the DEVELOPMENTS color lifetime, and the strength of the transverse quark- medium interaction. The published pion-nucleon cross The first physics aim of the experiment is to ex- sections were used for the baseline version of the model. plore fundamental characteristics of color propagation The fit to the data is shown in Fig.1. and hadron formation. These processes are unique to In the BL study the color lifetime was shown to depend QCD because of the non-Abelian nature of the strong on the standard SIDIS zh observable, zh = Eh/ν, with interaction that confines quarks into hadrons. With the exactly the magnitudes and functional dependence pre- data from this experiment we will extract the color life- dicted by the Lund String Model (LSM). A plot of these time of quasi-free quarks during the brief time that they results is shown in Fig.2, and in this figure it can be seen are liberated following a hard interaction in DIS kine- that the values found for the color lifetime range from 2 zh = 0.32 zh = 0.53 zh = 0.75 zh = 0.94 ) 2 0.02 (GeV i . 2 T 0 00 p h Model ∆ 0.02 Data − 0.8 Ne M R Kr Xe 0.6 Model Data 3 4 5 3 4 5 3 4 5 3 4 5 A1/3 A1/3 A1/3 A1/3 FIG. 1. Fits of the two-parameter BL model to HERMES published data. The fit is performed for two observables simultane- ously in a given bin in zh. 2 fm/c at high zh to 8 fm/c at lower zh. The curves in year 2000, Guo and Qiu determined that transverse mo- the fit correspond to two LSM analytical expressions for mentum broading is related to the quark-gluon correlator the color lifetime. The curve labeled LSM corresponds Tqg(xB; 0; 0) between energetic quarks and soft gluons[9]. to the color lifetime for the struck quark, and the other Using leading order pQCD, they determined the relation- curve takes into account the full string evolution. If the ship between pT broadening and Tqg(xB; 0; 0) to be: LSM string tension is left as a fit parameter, when fitted to the color lifetimes from the BL study of the HERMES 2 2 P 2 data, we find string tension values that are compatible 4π α z eqTqg(xB; 0; 0)Dh=q(zh) ∆ k2 = s h q (1) with 1 GeV/fm, the well-known magnitude of this quan- hT P 2 h i Nc q eqfq=A(xB)Dh=q(zh) tity. This result is a strong validation of the geometrical framework that was used for this analysis. where khT is the transverse momentum of the parton that fragments into the observed hadron h, and f and D are the usual parton distribution functions and frag- 2 LSM, χ /dof = 1.1 mentation functions. In 2016, Kang, Wang, Wang and κ = 1.04 0.06 (GeV/fm) ± Zing (KWWZ) reproduced this result from the year 2000 15 Bialas et. al, χ2/dof = 0.35 and extended it to next-to-leading-order (NLO) using the κ = 0.86 0.05 (GeV/fm) higher-twist collinear factorization framework[11]. They ± Fit result evaluated at NLO the transverse-momentum-weighted differential cross section d k2 σD =dx dydz at twist 4, (fm) B h 10 h hT i c considering contributions from quark-gluon and gluon- L gluon double scatterings, as well as interferences be- tween single and triple scatterings. They found that 5 2 D d khT σ =dxBdydzh can be factorized as a convolution ofh twist-4i nuclear parton correlation functions, the usual Q2 = 2.4 GeV2, ν = 12.4 GeV twist-2 fragmentation function, and hard parts which are h i h i finite and free of divergences. 0.0 0.2 0.4 0.6 0.8 1.0 Last year, Ru, Kang, Wang, Xing and Zhang (RK- z WXZ) [19] used the insights from the above efforts to perform a global fit to a variety of types of data, in- FIG. 2. A secondary fit of the results from the HERMES cluding the HERMES pT broadening, to constrain theq ^ fit to LSM analytical expressions for the color lifetime. The transport coefficient discussed earlier. The analysis took curve labelled "LSM" is for the struck quark, while the other into account the world data on transverse momentum curve is from Bialas and Gyulassy[3]. broadening in semi-inclusive electron-nucleus deep inelas- tic scattering, Drell-Yan dilepton and heavy quarkonium There have been substantial theory advances that are production in proton-nucleus collisions, as well as the directly relevant to this experiment since PAC 36 in 2010. nuclear modification of the structure functions in deep We list only a few here, due to space constraints. In the inelastic scattering, comprising a total of 215 data points 3 and K−. According to this work, quark energy loss plays a more minor role in describing the HERMES multiplic- ity ratios. The paper goes on to explore the implications for the LHC and the EIC. In a foundational theoretical effort, in 2013 Qin and Majumder derived a differential equation for the time evolution of the momentum distribution of a hard parton traveling through the nuclear medium[18]. This equa- tion describes in-medium evolution of hard jets which experience longitudinal drag and diffusion in addition to the transverse broadening caused by multiple scatterings from the medium. While the relative importance of lon- gitudinal drag vs. longitudinal diffusion may not yet be clear, collisional energy loss cannot simply be neglected in a theoretically correct description. This is not only true for the suppression of single inclusive hadrons, but also for jet shower evolution, energy loss distribution within 2 and outside the jet cone, as well as energy and momen- FIG. 3. Dependence ofq ^ on xBj and Q found by the RKWXZ theory collaboration tum deposition into the medium by the jet shower.
Load more

Recommended publications
  • SL Paper 3 Markscheme
    theonlinephysicstutor.com SL Paper 3 This question is about leptons and mesons. Leptons are a class of elementary particles and each lepton has its own antiparticle. State what is meant by an Unlike leptons, the meson is not an elementary particle. State the a. (i) elementary particle. [2] (ii) antiparticle of a lepton. b. The electron is a lepton and its antiparticle is the positron. The following reaction can take place between an electron and positron. [3] Sketch the Feynman diagram for this reaction and identify on your diagram any virtual particles. c. (i) quark structure of the meson. [2] (ii) reason why the following reaction does not occur. Markscheme a. (i) a particle that cannot be made from any smaller constituents/particles; (ii) has the same rest mass (and spin) as the lepton but opposite charge (and opposite lepton number); b. Award [1] for each correct section of the diagram. correct direction ; correct direction and ; virtual electron/positron; Accept all three time orderings. @TOPhysicsTutor facebook.com/TheOnlinePhysicsTutor c. (i) / up and anti-down; theonlinephysicstutor.com (ii) baryon number is not conserved / quarks are not conserved; Examiners report a. Part (a) was often correct. b. The Feynman diagrams rarely showed the virtual particle. c. A significant number of candidates had a good understanding of quark structure. This question is about fundamental interactions. The kaon decays into an antimuon and a neutrino as shown by the Feynman diagram. b.i.Explain why the virtual particle in this Feynman diagram must be a weak interaction exchange particle. [2] c. A student claims that the is produced in neutron decays according to the reaction .
    [Show full text]
  • Charmed Baryon Spectroscopy in a Quark Model
    Charmed baryon spectroscopy in a quark model Tokyo tech, RCNP A,RIKEN B, Tetsuya Yoshida,Makoto Oka , Atsushi HosakaA , Emiko HiyamaB, Ktsunori SadatoA Contents Ø Motivation Ø Formalism Ø Result ü Spectrum of single charmed baryon ü λ-mode and ρ-mode Ø Summary Motivation Many unknown states in heavy baryons ü We know the baryon spectra in light sector but still do not know heavy baryon spectra well. ü Constituent quark model is successful in describing Many unknown state baryon spectra and we can predict unknown states of heavy baryons by using the model. Σ Difference from light sector ΛC C ü λ-mode state and ρ-mode state split in heavy quark sector ü Because of HQS, we expect that there is spin-partner Motivation light quark sector vs heavy quark sector What is the role of diquark? How is it in How do spectrum and the heavy quark limit？ wave function change? heavy quark limit m m q Q ∞ λ , ρ mode ü we can see how the spectrum and wave-funcon change ü Is charm sector near from heavy quark limit (or far) ? Hamiltonian ij ij ij Confinement H = ∑Ki +∑(Vconf + Hhyp +VLS ) +Cqqq i i< j " % " % 2 π 1 1 brij 2α (m p 2m ) $ ' (r) $ Coul ' Spin-Spin = ∑ i + i i + αcon ∑$ 2 + 2 'δ +∑$ − ' i 3 i< j # mi mj & i< j # 2 3rij & ) # &, 2αcon 8π 3 2αten 1 3Si ⋅ rijS j ⋅ rij + + Si ⋅ S jδ (rij )+ % − Si ⋅ S j (. ∑ 3 % 2 ( Coulomb i< j *+3m i mj 3 3mimj rij $ rij '-. the cause of mass spliPng Tensor 1 2 2 4 l s C +∑αSO 2 3 (ξi +ξ j + ξiξ j ) ij ⋅ ij + qqq i< j 3mq rij Spin orbit ü We determined the parameter that the result of the Strange baryon will agree with experimental results .
    [Show full text]
  • Understanding the Ultimate Structure of Matters and Some Scientific Doubts of Nature Through Simple Hypotheses
    IOSR Journal of Applied Physics (IOSR-JAP) e-ISSN: 2278-4861.Volume 9, Issue 2 Ver. I (Mar. – Apr. 2017), PP 64-68 www.iosrjournals.org Understanding the Ultimate Structure of Matters and Some Scientific Doubts of Nature through Simple Hypotheses Bao-Yu Zong (Temasek Laboratories, National University of Singapore, Singapore) Abstract: There are numerous unanswered scientific doubts/phenomena in Nature which still perplex scientific researchers currently. To solve these puzzles, unveiling the ultimate structure of matters, which make up the Nature world, is essential. Here four hypotheses, namely the fundamental matter component (basic particle) and its property, construction process of the basic particles into other particles/matters, repulsion of particles of the same type, and direct relationship between matter and energy, are proposed. These simple hypotheses can well explain some natural phenomena, such as the existence of huge atom energy and various particles/matters of different properties, and conversion balance between matters and energy. Due to the existence of diverse infinite fine particles and repulsion of particles of the same types, matters and the Nature world are submerged in a sea of particles and there is not a real vacuum space (without any particle) in the Nature world. This in turn reveals Thermal Laws, the component of dark energy/matter, as well as a minimum temperature of ~3K that exists in the deep Universe. The suggested relationships between particles and/or matters also shed light on the mechanisms of interaction forces of same or different polarity particles, and intermedia of gravitational, electrical and magnetic fields. Keywords: Basic particle, elementary particle, dark energy/matter, smallest transporter of energy, fundamental component of matter I.
    [Show full text]
  • Ask a Scientist Answers
    Ask a scientist answers. GN I quote the beginning of the question, then my answer: Q11: “Since beta decay is when …” A11: Good question. The weak force is responsible for changing one quark into another, in this case a d-quark into a u-quark. Because the electric charge must conserved one needs to emit a negative charge (the neutron is neutral, the proton is +1, so you need a -1- type particle). In principle there could be other -1 particles emitted (say a mu-) but nature is lazy and will go with the easiest to come by (as in the “lowest possible energy” needed to do the job) particle, an electron. Of course, because we have an electron in the final state now we also need a matching anti-neutrino, as the lepton number (quantum number that counts the electrons, neutrinos, and their kind – remember the slide with the felines in my presentation) needs to be conserved as well. Now, going back to your original question “…where they come from?” the energy of the original nucleus. Remember E=m * c^2. That is a recipe for creating particles (mass) if one has enough initial energy. In this case in order for the beta decay to occur (naturally) you need the starting nucleus to have a higher sum of the energies of the daughter nucleus one gets after decay and the energies of the electron and antineutrino combined. That energy difference can then be “spent” in creating the mass of the electron and antineutrino (and giving them, and the daughter nucleus some kinetic energy, assuming there are energy leftovers).
    [Show full text]
  • Reconstruction Study of the S Particle Dark Matter Candidate at ALICE
    Department of Physics and Astronomy University of Heidelberg Reconstruction study of the S particle dark matter candidate at ALICE Master Thesis in Physics submitted by Fabio Leonardo Schlichtmann born in Heilbronn (Germany) March 2021 Abstract: This thesis deals with the sexaquark S, a proposed particle with uuddss quark content which might be strongly bound and is considered to be a reasonable dark matter can- didate. The S is supposed to be produced in Pb-Pb nuclear collisions and could interact with detector material, resulting in characteristic final states. A suitable way to observe final states is using the ALICE experiment which is capable of detecting charged and neutral particles and doing particle identification (PID). In this thesis the full reconstruction chain for the S particle is described, in particular the purity of particle identification for various kinds of particle species is studied in dependence of topological restrictions. Moreover, nuclear interactions in the detector material are considered with regard to their spatial distribution. Conceivable reactions channels of the S are discussed, a phase space simulation is done and the order of magnitude of possibly detectable S candidates is estimated. With regard to the reaction channels, various PID and topology cuts were defined and varied in order to find an S candidate. In total 2:17 · 108 Pb-Pb events from two different beam times were analyzed. The resulting S particle candidates were studied with regard to PID and methods of background estimation were applied. In conclusion we found in the channel S + p ! ¯p+ K+ + K0 + π+ a signal with a significance of up to 2.8, depending on the cuts, while no sizable signal was found in the other studied channels.
    [Show full text]
  • Particle Mass Ratios Nearly Equaling Geometric Ratios, More Examples
    x Particle Mass Ratios nearly equaling Geometric Ratios, more examples Carl Littmann 25 Washington Lane #313, Wyncote PA 19095 USA [email protected] April 2021 Abstract There are many important Particle Mass ratios in Physics, such as the 'Proton to electron' mass ratio, about 1836.15 to 1. And there are many major Volumetric ratios in 'Solid Geometry', some of which we may have seen in high school. And, remarkably, some of the major particle Mass ratios nearly equal some of those major geometric Volumetric ratios! This article gives many additional examples of these matches, which couldn't be included in my earlier article - which preferably should be read first. Ref. https://www.gsjournal.net/Science-Journals/Research%20Papers-Quantum%20Theory%20/%20Particle%20Physics/Download/6726 (But even both articles don't give all the important examples -- to prevent unwieldy length.) Keywords: Particle mass ratios, Geometric volume ratios, 1836.15 to 1, Proton to electron mass ratio Introduction As implied by the above Abstract, the goal of this article is to find out why the different Particles in physics have the different masses they do! And that was the goal of many Nobel Laureates. But that goal illuded them. But this article largely succeeds. In many cases, we have importantly discovered that a major particle mass ratio, existing in Nature, nearly equals a volume ratio in a basic, symmetrical sphere pattern. In many cases, we have also found that the Average of two different major volumetric ratios nearly equals a major particle mass ratio. Or simply averaging the masses of two different particles together -- nearly equals the mass of a third particle! Quite remarkable, and unlikely to be just 'chance'.
    [Show full text]
  • Group Theoretic Classification of Pentaquarks and Numerical Predictions of Their Masses
    DEGREE PROJECT IN TECHNOLOGY, FIRST CYCLE, 15 CREDITS STOCKHOLM, SWEDEN 2019 Group Theoretic Classification of Pentaquarks and Numerical Predictions of Their Masses PONTUS HOLMA KTH ROYAL INSTITUTE OF TECHNOLOGY SCHOOL OF ENGINEERING SCIENCES EXAMENSARBETE INOM TEKNIK, GRUNDNIVÅ, 15 HP STOCKHOLM, SVERIGE 2019 Gruppteoretisk klassificering av pentakvarkar och numeriska förutsägelser av deras massor PONTUS HOLMA KTH SKOLAN FÖR ARKITEKTUR OCH SAMHÄLLSBYGGNAD Abstract In this report we investigate the exotic hadrons known as pentaquarks. A brief overview of relevant concepts and theory is initially presented in order to aid the reader. There- after, the history of this field with regards to theory and experiments is discussed. In particular, a group theoretic classification of these states is studied. A simple mass for- mula for pentaquark states is examined and predictions are subsequently made about the composition and mass of possible pentaquark states. Furthermore, this mass formula is modified to examine and predict additional pentaquark states. A number of numerical fits concerning the masses of pentaquarks are performd and studied. Future research is explored with regards to the information presented in this thesis. Sammanfattning I denna uppsats unders¨oker vi de exotiska hadronerna k¨andasom pentakvarkar. En kort ¨overblick av relevanta koncept och teorier ¨arpresenterade med syfte att underl¨atta f¨orl¨asaren. Historia i detta omr˚ademed avseende p˚ab˚adeteori och experiment ¨ar presenterad. Specifikt ing˚aren unders¨okningav gruppteoretisk klassificering av dessa tillst˚and.En enkel formel f¨ormassan hos pentakvarkar unders¨oksoch anv¨andsf¨oratt f¨orutsp˚amassorna och uppbyggnaden av m¨ojligapentakvarktillst˚and. Dessutom modi- fieras denna formel f¨oratt studera och f¨orutsp˚aytterligare pentakvarktillst˚and.Ett antal numeriska anpassningar relaterade till massorna hos pentakvarkarna genomf¨orsoch un- ders¨oks.Framtida forskning unders¨oksi koppling med material presenterat i uppsatsen.
    [Show full text]
  • © in This Web Service Cambridge University Press
    Cambridge University Press 978-1-107-40426-7 - The Standard Model: A Primer C. P. Burgess and Guy D. Moore Index More information Index 2π counting, 156 Anomalous magnetic moment of a proton, 322 1 ∆I = 2 Rule, 356 Anomaly matching, 365 ∆ baryon, 302 Anti-fundamental representation, 491 Λ baryon, 302 Antiparticles, 14 Ω baryon, 302 Antisymmetry of the baryonic wave function, Σ baryon, 302 301 Σ∗ baryon, 302 Asymmetries, left-right, 199 Θ3, and electric dipole moments, 464 Asymmetry, forward-backward, 200 Ξ baryon, 302 Asymptotic freedom, 454 Ξ gauges, 506 Atmospheric neutrino oscillations, 402 Ξ∗ baryon, 302 Axioms of field theory, 7 γ5, convention for, 518 Axion, 459 ΛQCD, 278 Axion potential, 467 ρ parameter, 236 Axions, as cold dark matter, 468 SUc(3) SUL(2) UY (1), 54 × × B-L conservation, 104 A terms, Supersymmetry breaking, 450 B-L symmetry, gauged, 108 Abelian Higgs model, 41 BaBar experiment, 229 Accidental conservation laws, in the standard Barn, 197 model, 96 Baryon masses, 300 Accidental symmetries, 239, 241 Baryon masses, and chiral symmetry breaking, Accidental symmetries, and the Fermi theory, 316 241 Baryon number, 96, 286 Accidental symmetry, 68 Baryon number, anomalies, 102 Action, 12 Baryon number, of QCD bound states, 287 Ademollo-Gatto theorem, 324, 361 Baryons, 71, 281 Adjoint Higgs models, 107 Baryons, and flavor symmetry, 300 Adjoint representation, 490 Baryons, defined, 281 Altarelli-Parisi (DGLAP) equations, 347 Baryons, octet and decuplet, 302 Angular momentum operators, 497 Baryons, valence quark content of, 302
    [Show full text]
  • Carnegie Mellon University MELLON COLLEGE of SCIENCE
    Carnegie Mellon University MELLON COLLEGE OF SCIENCE THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN THE FIELD OF PHYSICS TITLE: "Masses and Weak Decay Properties of Heavy-quark Baryons from QCD Sum Rules and Production of Heavy Mesons in High Energy Collisions." PRESENTED BY: Bijit Singha ACCEPTED BY THE DEPARTMENT OF PHYSICS Leonard Kisslinger 8/22/19 LEONARD KISSLINGER, CHAIR PROFESSOR DATE Scott Dodelson 8/21/19 SCOTT DODELSON, DEPT HEAD DATE APPROVED BY THE COLLEGE COUNCIL Rebecca Doerge 8/22/19 REBECCA DOERGE, DEAN DATE Masses and Weak Decay Properties of Heavy-quark Baryons from QCD Sum Rules and Production of Heavy Mesons in High Energy Collisions Bijit Singha Dissertation submitted to the Faculty of the Carnegie Mellon University in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Physics Leonard S. Kisslinger, Chair Eric S. Swanson Ira Z. Rothstein Scott Dodelson August, 2019 Pittsburgh, Pennsylvania Copyright 2019, Bijit Singha Masses and Weak Decay Properties of Heavy-quark Baryons from QCD Sum Rules and Production of Heavy Mesons in High Energy Collisions Bijit Singha (ABSTRACT) Quantum Chromodynamics Sum Rules (QCD Sum Rules) is a non-perturbative technique which uses Wilson’s Operator Product Expansion of n-point functions and quark-hadron duality together to extract various physical properties of hadrons. In this dissertation, we use + 0 QCD Sum Rules to calculate the masses of charmed lambda (Λc ), strange lambda (Λ ), and 0 bottom lambda (Λb ) baryons. We extend this framework to consider charm to strange quark transition in the presence of an external pion field to estimate the coupling corresponding + ! 0 + to the Cabibbo-favored weak decay process: Λc Λ + π .
    [Show full text]
  • Meson and Baryon Spectrum for QCD with Two Light Dynamical Quarks
    Meson and baryon spectrum for QCD with two light dynamical quarks Georg P. Engel1, C. B. Lang1, Markus Limmer1, Daniel Mohler1,2, and Andreas Sch¨afer3 (BGR [Bern-Graz-Regensburg] Collaboration) 1Institut f¨ur Physik, FB Theoretische Physik, Universit¨at Graz, A–8010 Graz, Austria 2TRIUMF, 4004 Wesbrook Mall Vancouver, BC V6T 2A3, Canada 3Institut f¨ur Theoretische Physik, Universit¨at Regensburg, D–93040 Regensburg, Germany (Dated: November 4, 2018) We present results of meson and baryon spectroscopy using the Chirally Improved Dirac operator on lattices of size 163 × 32 with two mass-degenerate light sea quarks. Three ensembles with pion masses of 322(5), 470(4) and 525(7) MeV and lattice spacings close to 0.15 fm are investigated. Results for ground and excited states for several channels are given, including spin two mesons and hadrons with strange valence quarks. The analysis of the states is done with the variational method, including two kinds of Gaussian sources and derivative sources. We obtain several ground states fairly precisely and find radial excitations in various channels. Excited baryon results seem to suffer from finite size effects, in particular at small pion masses. We discuss the possible appearance of scattering states, considering masses and eigenvectors. Partially quenched results in the scalar channel suggest the presence of a 2-particle state, however, in most channels we cannot identify them. Where available, we compare our results to results of quenched simulations using the same action. PACS numbers: 11.15.Ha, 12.38.Gc I. INTRODUCTION fermions are very expensive, typically two orders of mag- nitude more expensive than simulations with the simple, The overwhelming majority of hadronic states in the improved Wilson Dirac operator.
    [Show full text]
  • Status of Xic0 Analysis Using Semileptonic Decay Channel in P+
    Status of Xic0 analysis using semileptonic decay channel in p+Pb collisions Nov 16th 2019 Jeongsu Bok (Inha University) Motivation • Heavy quarks are • sensitive probes to study the Quark-Gluon Plasma in heavy-ion coll isions. • Due to their large masses, they are formed in initial hard scattering of parton before the timescale of QGP formation • àproduced early in the collision, live long enough to sample QGP • experience the whole system evolution • Baryon containing Heavy Quark • Charm-baryon measurements provide unique insight into hadroniz ation processes • Baryon-to-Meson ratio is expected to be higher in p+Pb and Pb+Pb 11/16/19 2 Charmed baryon-to-meson ratio • Charmed baryon-to-meson ratio in p+p and p+Pb higher tha n than model calculations 11/16/19 3 0 0 �c / D • Phys. Lett. B. 781 (2018) 8–19 • Theories underestimate it 11/16/19 4 Charmed baryon-to-meson ratio in Pb+Pb • Enhancement in Pb+Pb • Compatible with models that include recombination 11/16/19 5 Charmed baryon-to-meson ratio in terms of multiplicity • Increase from low to high multiplicity • ratio in high multiplicity in pp comparable Pb-Pb • àrecombination already saturated in p+p? 11/16/19 6 0 + �c (�c ) • Charm hadronization not fully understood • à we need more result with different channel such as �c • Possibility to be hadronized via coalescence in QGP? • Strange enhancement? • Multiplicity dependence? 11/16/19 7 0 Studying �c using semi-leptonic decay • Analysis procedure • Reconstruct �- Hadronic decay channel: 0 • Reconstruct electron �c à π+ Ξ- → π+ π- Λ →
    [Show full text]
  • Lambda Production and Its Asymmetry
    Lambda production and its asymmetry Daisuke Tatsumi Nagashima group, Faculty of Science, Osaka University 1-1 Machikaneyama cho, Toyonaka City, 560 Japan ( VENUS Collaboration ) Abstract Differential cross section and asymmetry for A0, A0 production have been measured in e+e~ annihilation at 58 GeV in the scaled momentum Xp range from 0.0 to 0.25. Using 241 pb"1 of data collected after VENUS detector upgrade in 1991. 1 Introduction Study of lambda baryon results the following informations. At low momentum re- gion, we can get the information about baryon production mechanism. For example, diquark production ratio, popcorn ratio, and so on. Diquark production ratio is the ratio of diquark-antidiquark and quark-antiquark pair production in the color field. This parameter will change total baryon cross section, popcorn ratio is a parameter determining relative occurrence of baryon production by BMB and by BB configu- ration. Here B is a baryon, M is a meson. In the popcorn mechanism, a meson exists between two baryons. This parameter will change baryon anti-baryon correlation. The smaller this parameter, the closer two baryons in the phase space. At High momentum region, we can get the primary s-quark information. Because the higher lambda momentum, the more s-quark events fraction. Figure ??? shows fraction of s-quark events by lambda tagging. The ratio of total ss cross-section and total hadron cross-section is about 12%, so at high momentum region we can enhance s-quark events by lambda tagging and s-quark asymmetry will be given us from the lambda asymmetry.
    [Show full text]