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Nuclear Theory·nucl-th

Tuesday·October 17, 2017

11 papers—5 primary·6 cross-listed

All11Primary5Cross-lists6
  1. 06

    An effective field theory for warm QCD

    Sourendu Gupta🇮🇳 · Rishi Sharma🇮🇳

    Using only global symmetries of QCD, we set up an effective model of quarks at finite temperature near the cross over, including all possible terms up to dimension 6. We first treat this in mean field theory. Then we investigate low-energy fluctuations around it up to one-loop order in fermions below the cross over. Static correlation functions of pions and the cross over temperature, both measured on the lattice, completely suffice to fix all parameters of the theory. We examine predictions of this theory, including those for thermodynamic quantities. The results are encouraging.

    ↳ hep-phhep-latnucl-thPRD(2018)·13 citations
  2. 07

    The effect of quantum fluctuations in compact star observables

    Péter Pósfay🇭🇺 · Gergely Gábor Barnaföldi🇭🇺 · Antal Jakovác🇭🇺

    Astrophysical measurements regarding compact stars are just ahead of a big evolution jump, since the NICER experiment deployed on ISS on 14 June 2017. This will soon provide data that would enable the determination of compact star radius with less than 10% error. This poses new challenges for nuclear models aiming to explain the structure of super dense nuclear matter found in neutron stars. Detailed studies of the QCD phase diagram shows the importance of bosonic quantum fluctuations in the cold dense matter equation of state. Here, we using a demonstrative model to show the effect of bosonic quantum fluctuations on compact star observables such as mass, radius, and compactness. We have also calculated the difference in the value of compressibility which is caused by quantum fluctuations. The above mentioned quantities are calculated in mean field, one-loop and in high order many-loop approximation. The results show that the magnitude of these effects is ~5%, which place it into the region where forthcoming high-accuracy measurements may detect it.

    ↳ hep-phastro-ph.HEgr-qcnucl-thPubl.Astron.Soc.Austral.(2018)·4 citations
  3. 08

    interaction from lattice QCD and its application to hypernuclei

    Takaya Miyamoto🇯🇵 · Sinya Aoki🇯🇵 · Takumi Doi🇯🇵 · Shinya Gongyo🇯🇵 · Tetsuo Hatsuda🇯🇵 · Yoichi Ikeda🇯🇵 · Takashi Inoue🇯🇵 · Takumi Iritani🇯🇵 · Noriyoshi Ishii🇯🇵 · Daisuke Kawai🇯🇵 · Keiko Murano🇯🇵 · Hidekatsu Nemura🇯🇵 · Kenji Sasaki🇯🇵

    The interaction between and a nucleon () is investigated by employing the HAL QCD method in the (2+1)-flavor lattice QCD on a volume at MeV. We study the central potential in channel as well as central and tensor potentials in channel, and find that the tensor potential for is negligibly weak and central potentials in both and channels are almost identical with each other except at short distances. Phase shifts and scattering lengths calculated with these potentials show that the interaction of system is attractive and has a similar strength in and channels at low energies (i.e. the kinetic energy less than about MeV). While the attractions are not strong enough to form two-body bound states, our results lead to a possibility to form hypernuclei for sufficiently large atomic numbers (). To demonstrate this, we derive a single-folding potential for hypernuclei from the -nucleon potential obtained in lattice QCD, and find that hypernuclei can exist for with the binding energies of a few MeV. We also estimate the Coulomb effect for the hypernuclei.

    ↳ hep-lathep-phnucl-thNPA(2018)·57 citations
  4. 09

    Calm Multi-Baryon Operators

    Evan Berkowitz🇩🇪 · Amy Nicholson🇺🇸 · Chia Cheng Chang🇺🇸 · Enrico Rinaldi🇺🇸 · M.A. Clark🇺🇸 · Bálint Joó🇺🇸 · Thorsten Kurth🇺🇸 · Pavlos Vranas🇺🇸 · André Walker-Loud🇺🇸

    Outstanding problems in nuclear physics require input and guidance from lattice QCD calculations of few baryons systems. However, these calculations suffer from an exponentially bad signal-to-noise problem which has prevented a controlled extrapolation to the physical point. The variational method has been applied very successfully to two-meson systems, allowing for the extraction of the two-meson states very early in Euclidean time through the use of improved single hadron operators. The sheer numerical cost of using the same techniques in two-baryon systems has been prohibitive. We present an alternate strategy which offers some of the same advantages as the variational method while being significantly less numerically expensive. We first use the Matrix Prony method to form an optimal linear combination of single baryon interpolating fields generated from the same source and different sink interpolators. Very early in Euclidean time this linear combination is numerically free of excited state contamination, so we coin it a calm baryon. This calm baryon operator is then used in the construction of the two-baryon correlation functions. To test this method, we perform calculations on the WM/JLab iso-clover gauge configurations at the SU(3) flavor symmetric point with m{\pi} 800 MeV --- the same configurations we have previously used for the calculation of two-nucleon correlation functions. We observe the calm baryon removes the excited state contamination from the two-nucleon correlation function to as early a time as the single-nucleon is improved, provided non-local (displaced nucleon) sources are used. For the local two-nucleon correlation function (where both nucleons are created from the same space-time location) there is still improvement, but there is significant excited state contamination in the region the single calm baryon displays no excited state contamination.

    ↳ hep-latnucl-thEPJ Web Conf.(2018)·8 citations
  5. 10

    Study of spin-dependent structure functions of and at NNLO approximation and corresponding nuclear corrections

    Hamzeh Khanpour🇮🇷 · S. Taheri Monfared🇮🇷 · S. Atashbar Tehrani🇮🇷

    We determine polarized parton distribution functions (PPDFs) and structure functions from recent experimental data of polarized deep inelastic scattering (DIS) on nuleons at next-to-next-to-leading order (NNLO) approximation in perturbative quantum chromodynamic (pQCD). The nucleon polarized structure functions are computed using the Jacobi polynomial approach while target mass corrections (TMCs) are included in our fitting procedure. Having extracted the polarized spin structure functions, we extend our study to describe and polarized structure functions, as well as the Bjorken sum rule. We also explore the importance of the nuclear corrections on the polarized nuclear structure functions at small and large values of . Our results are compared with the recent available and high precision polarized and experimental data.

    ↳ hep-phhep-exnucl-thPRD(2017)·24 citations
  6. 11

    Exact evolution equation for the effective potential

    Christof Wetterich🇩🇪

    We derive a new exact evolution equation for the scale dependence of an effective action. The corresponding equation for the effective potential permits a useful truncation. This allows one to deal with the infrared problems of theories with massless modes in less than four dimensions which are relevant for the high temperature phase transition in particle physics or the computation of critical exponents in statistical mechanics.

    ↳ hep-thcond-mat.quant-gascond-mat.str-elgr-qc+1PLB(1993)·2294 citations

Affiliations

first authorsco-authorsvia INSPIRE