Nuclear Theory·nucl-th

Tuesday·July 16, 2019

12 papers—4 primary·8 cross-listed

05
Probing Transverse-Momentum Dependent Evolution With Groomed Jets
Yiannis Makris🇺🇸 · Duff Neill🇺🇸 · Varun Vaidya🇺🇸
We propose an observable which involves measuring the properties (transverse momentum $p_{h ⊥}$ and energy fraction $z_{h}$ ) of an identified hadron inside a groomed jet. The jet is identified with an anti-kT/CA algorithm and is groomed by implementing the modified mass drop procedure with an energy cut-off parameter $z_{c u t}$ . The transverse momentum of the hadron inside the jet is measured with respect to the groomed jet axis. We obtain a factorization theorem in the framework of Soft Collinear Effective Theory (SCET), to define a Transverse Momentum Dependent Fragmenting Jet Function (TMDFJF). The TMDFJF is factorized into collinear and collinear soft modes by matching onto SCET $_{+}$ . We resum large logarithms in $E_{J} / p_{h ⊥}$ , where $E_{J}$ is the ungroomed jet energy, to NLL accuracy and apply this formalism for computing the shape of the $p_{h ⊥}$ distribution of a pion produced in an $e^{+} + e^{-}$ collision. We observe that the introduction of grooming makes this observable insensitive to non-global logarithms and particularly sensitive to non-perturbative physics of the transverse momentum dependent evolution at low values of $p_{h ⊥}$ , which can be probed in the variation of the cut-off parameter $z_{c u t}$ of the groomer. We discuss how this observable can be used to distinguish between non-perturbative models that describe universal TMD evolution and provide a window into the three dimensional structure of hadrons.
↳ hep-phnucl-thJHEP(2018)·38 citations
06
Baryon as a Quantum Hall Droplet and the Cheshire Cat Principle
Yong-Liang Ma🇨🇳 · Maciej A. Nowak🇵🇱 · Mannque Rho🇫🇷 · Ismail Zahed🇺🇸
We show that the recent proposal to describe the $N_{f} = 1$ baryon in the large number of color limit as a quantum Hall droplet, can be understood as a chiral bag in a 1+2 dimensional strip using the Cheshire cat principle. For a small bag radius, the bag reduces to a vortex line which is the smile of the cat with flowing gapless quarks all spinning in the same direction. The disc enclosed by the smile is described by a topological field theory due to the Callan-Harvey anomaly out-flow. The chiral bag carries naturally unit baryon number and spin $\frac{1}{2} N_{c}$ . The generalization to arbitrary $N_{f}$ is discussed.
↳ hep-thhep-phnucl-thPRL(2019)·35 citations
07
Probing Transverse-Momentum Distributions With Groomed Jets
Daniel Gutierrez-Reyes🇪🇸 · Yiannis Makris🇺🇸 · Varun Vaidya🇺🇸 · Ignazio Scimemi🇪🇸 · Lorenzo Zoppi🇳🇱
We present the transverse momentum spectrum of groomed jets in di-jet events for $e^{+} e^{-}$ collisions and semi-inclusive deep inelastic scattering (SIDIS). The jets are groomed using a soft-drop grooming algorithm which helps in mitigating effects of non-global logarithms and underlying event. At the same time, by reducing the final state hadronization effects, it provides a clean access to the non-perturbative part of the evolution of transverse momentum dependent (TMD) distributions. In SIDIS experiments we look at the transverse momentum of the groomed jet measured w.r.t. the incoming hadron in the Breit frame. Because the final state hadronization effects are significantly reduced, the SIDIS case allows to probe the TMD parton distribution functions. We discuss the sources of non-perturbative effects in the low transverse momentum region including novel (but small) effects that arise due to grooming. We derive a factorization theorem within SCET and resum any large logarithm in the measured transverse momentum up to NNLL accuracy using the $ζ$ -prescription as implemented in the artemide package and provide a comparison with simulations.
↳ hep-phhep-exnucl-exnucl-thJHEP(2019)·57 citations
08
Matter And Gravitation In Collisions of heavy ions and neutron stars: equation of state
Anton Motornenko🇩🇪 · Jan Steinheimer🇩🇪 · Volodymyr Vovchenko🇩🇪 · Stefan Schramm🇩🇪 · Horst Stoecker🇩🇪
The gravitational waves emitted from a binary neutron star merger, as predicted from general relativistic magneto-hydrodynamics calculations, are sensitive to the appearance of quark matter and the stiffness of the equation of state of QCD matter present in the inner cores of the stars. This is a new messenger observable from outer space, which does provide direct signals for the phase structure of strongly interacting QCD matter at high baryon density and high temperature. These astrophysically created extremes of thermodynamics do match, to within 20\%, the values of densities and temperatures which we find in relativistic hydrodynamics and transport theory of heavy ion collisions at the existing laboratories, if though at quite different rapidity windows, impact parameters and bombarding energies of the heavy nuclear systems. We demonstrate how one unified equation of state can be constructed and used for both neutron star physics and hot QCD matter excited at laboratory facilities. The similarity in underlying QCD physics allows the gravitational wave signals from future advanced LIGO and Virgo events to be combined with the analysis of high multiplicity fluctuations and flow measurements in heavy ion detectors in the lab to pin down the EoS and the phase structure of dense matter.
↳ hep-phastro-ph.HEnucl-thPoS(2019)·5 citations
09
Spin-parities of the $P_{c} (4440)$ and $P_{c} (4457)$ in the One-Boson-Exchange Model
Ming-Zhu Liu🇨🇳 · Tian-Wei Wu🇨🇳 · Mario Sánchez Sánchez🇫🇷 · Manuel Pavon Valderrama🇨🇳 · Li-Sheng Geng🇨🇳 · Ju-Jun Xie🇨🇳
The LHCb collaboration has recently observed three pentaquark peaks, the $P_{c} (4312)$ , $P_{c} (4440)$ and $P_{c} (4457)$ . They are very close to a pair of heavy baryon-meson thresholds, with the $P_{c} (4312)$ located $8.9 MeV$ below the $D ˉ Σ_{c}$ threshold, and the $P_{c} (4440)$ and $P_{c} (4457)$ located $21.8$ and $4.8 MeV$ below the $D ˉ^{*} Σ_{c}$ one. The spin-parities of these three states have not been measured yet. In this work we assume that the $P_{c} (4312)$ is a $J^{P} = \frac{1}{2}^{-}$ $D ˉ Σ_{c}$ bound state, while the $P_{c} (4440)$ and $P_{c} (4457)$ are $D ˉ^{*} Σ_{c}$ bound states of unknown spin-parity, where we notice that the consistent description of the three pentaquarks in the one-boson-exchange model can indeed determine the spin and parities of the later, i.e. of the two $D ˉ^{*} Σ_{c}$ molecular candidates. For this determination we revisit first the one-boson-exchange model, which in its original formulation contains a short-range delta-like contribution in the spin-spin component of the potential. We argue that it is better to remove these delta-like contributions because, in this way, the one-boson-exchange potential will comply with the naive expectation that the form factors should not have a significant impact in the long-range part of the potential (in particular the one-pion-exchange part). Once this is done, we find that it is possible to consistently describe the three pentaquarks, to the point that the $P_{c} (4440)$ and $P_{c} (4457)$ can be predicted from the $P_{c} (4312)$ within a couple of MeV with respect to their experimental location. In addition the so-constructed one-boson-exchange model predicts the preferred quantum numbers of the $P_{c} (4440)$ and $P_{c} (4457)$ molecular pentaquarks to be $\frac{3}{2}^{-}$ and $\frac{1}{2}^{-}$ , respectively.
↳ hep-phhep-exnucl-thPRD(2021)·110 citations
10
Power corrections in semi-inclusive deep inelastic scatterings at fixed target energies
Tianbo Liu🇺🇸 · Jian-Wei Qiu🇺🇸
The COMPASS collaboration published precise data on production cross section of charged hadrons in lepton-hadron semi-inclusive deep inelastic scattering, showing almost an order of magnitude larger than next-to-leading order QCD calculations when $P_{h_{T}}$ and $z_{h}$ are sufficiently large. We explore the role of power corrections to the theoretical calculations, and quantitatively demonstrate that the power corrections are extremely important for these data when the final-state multiplicity is low and the production kinematics is near the edge of phase space. Our finding motivates more detailed studies on power corrections for upcoming experiments at Jefferson Lab, as well as the future Electron-Ion Collider.
↳ hep-phhep-exnucl-exnucl-thPRD(2020)·13 citations
11
Baryon-baryon interactions at short distances -- constituent quark model meets lattice QCD
Aaron Park🇰🇷 · Su Houng Lee🇰🇷 · Takashi Inoue🇯🇵 · Tetsuo Hatsuda🇯🇵
The interaction energies between two baryons at short distance in different flavor channels are calculated from the constituent quark model (CQM) and are compared with the recent lattice QCD (LQCD) results for baryon-baryon potentials at short distance. We consider the six-quark system with two strange quarks and focus on the quantum numbers, (Flavor,Spin)=(1,0),(8,1),(10,1),( $10$ ,1) and (27,0). The interaction energy is defined by subtracting out isolated baryon masses and relative kinetic energy of two baryons from the total energy of a compact six-quark state. We introduce interaction energy ratio between different flavors as a useful measure to test the prediction of CQM. We find that the ratios in CQM show good agreement with those in LQCD, which indicates that the short range part of the baryon-baryon interaction can be understood qualitatively in terms of the Pauli principle and spin-dependent color interaction among constituent quarks.
↳ hep-phhep-latnucl-thEPJA(2020)·30 citations
12
Competing quasifission and asymmetric fusion-fission in neutron-deficient sub-lead nuclei
Shilpi Gupta🇮🇳 · K. Mahata🇮🇳 · A. Shrivastava🇮🇳 · K. Ramachandran🇮🇳 · S.K. Pandit🇮🇳 · P.C. Rout🇮🇳 · V.V. Parkar🇮🇳 · R. Tripathi🇮🇳 · A. Kumar🇮🇳 · B.K. Nayak🇮🇳 · E.T. Mirgule🇮🇳 · A. Saxena🇮🇳 and 6 other authors
To disentangle the role of shell effects and dynamics, fission fragment mass distributions of $^{191}$ Au, a nucleus in the newly identified island of mass asymmetric fission in the sub-lead region, have been measured down to excitation energy of $\approx$ 20 MeV above the fission barrier via two different entrance channels, viz. $^{16}$ O+ $^{175}$ Lu and $^{37}$ Cl+ $^{154}$ Sm reactions. Apart from having signature of the shell effects in both the cases, clear experimental evidence of quasifission has been observed in the mass distributions of the Cl induced reaction, that has also been substantiated by the theoretical calculations. This crucial evidence along with a systematic analysis of available experimental data has revealed that the dynamics in the entrance channel has significant influence on most of the reactions used earlier to explore the persistence of recently discovered mass asymmetry in $β$ -delayed fission at low energy in this mass region, ignoring which might lead to ambiguity in interpreting the heavy-ion data.
↳ nucl-exnucl-thPLB(2020)·31 citations

Affiliations

first authorsco-authorsvia INSPIRE