Mon·Apr 27, 2020Monday·April 27, 2020

1. 01*

   Transverse Momentum Broadening of a Jet in Quark-Gluon Plasma: An Open Quantum System EFT

   Varun Vaidya🇺🇸 · Xiaojun Yao🇺🇸

   We utilize the technology of open quantum systems in conjunction with the recently developed effective field theory for forward scattering to address the question of massless jet propagation through a weakly-coupled quark-gluon plasma in thermal equilibrium. We discuss various possible hierarchies of scales that may appear in this problem, by comparing thermal scales of the plasma with relevant scales in the effective field theory. Starting from the Lindblad equation, we derive and solve a master equation for the transverse momentum distribution of a massless quark jet, at leading orders both in the strong coupling and in the power counting of the effective field theory. Markovian approximation is justified in the weak coupling limit. Using the solution to the master equation, we study the transverse momentum broadening of a jet as a function of the plasma temperature and the time of propagation. We discuss the physical origin of infrared sensitivity that arises in the solution and a way to handle it in the effective field theory formulation. We suspect that the final measurement constraint can only cut-off leading infrared singularities and the solution to the Markovian master equation resums a logarithmic series. This work is a stepping stone towards understanding jet quenching and jet substructure observables on both light and heavy quark jets as probes of the quark-gluon plasma.

   hep-phnucl-thJHEP(2020)·41 citations
2. 02*

   How low-scale Trinification sheds light in the flavour hierarchies, neutrino puzzle, dark matter and leptogenesis

   A. E. Cárcamo Hernández🇨🇱 · D. T. Huong🇻🇳 · Sergey Kovalenko🇨🇱 · Antonio P. Morais🇵🇹 · Roman Pasechnik🇸🇪 · Ivan Schmidt🇨🇱

   We propose a low-scale renormalizable trinification theory that successfully explains the flavor hierarchies and neutrino puzzle in the Standard Model (SM), as well as provides a dark matter candidate and also contains the necessary means for efficient leptogenesis. The proposed theory is based on the trinification $\text{SU}3C\times \text{SU}3L\times \text{SU}3R$ gauge symmetry, which is supplemented with an additional flavor symmetry $\text{U}X\times Z_2^{(1)}\times Z_2^{(2)}$. In the proposed model the top quark and the exotic fermions acquire tree-level masses, whereas the lighter SM charged fermions gain masses radiatively at one-loop level. In addition, the light active neutrino masses arise from a combination of radiative and type-I seesaw mechanisms, with the Dirac neutrino mass matrix generated at one-loop level.

   hep-phPRD(2020)·9 citations
3. 03*

   Hadron Form Factors with the Boost-Corrected Wave Functions

   Yu.A. Simonov🇷🇺

   Hadron form factors are calculated using the Lorentz contracted wave functions, determined in the arbitrary dynamical scheme with the instantaneous interaction. It is shown that the large $Q$ asymptotics of the form factors is defined by the contraction coefficient $C_m(Q^2)=\frac{m}{\sqrt{(}{m}^2+Q^2/4)}$, where $m$ is the meson mass, and weakly depends on the interaction used. The resulting form factors $F_{\pi }$ and $F_K$ are obtained in good agreement with the lattice and experimental data. Important consequences for the dynamics of hadron decays and scattering are shortly discussed.

   hep-phhep-exhep-latPhys.Atom.Nucl.(2021)·5 citations
4. 04*

   Sensitivity Reach on the Heavy Neutral Leptons and $\tau$-Neutrino Mixing $|U_{\tau N}{|}^2$ at the HL-LHC

   Kingman Cheung🇹🇼 · Yi-Lun Chung🇹🇼 · Hiroyuki Ishida🇯🇵 · Chih-Ting Lu🇰🇷

   The model of heavy neutral leptons (HNLs) is one of the well-motivated models beyond the standard model (BSM) from both theoretical and phenomenological point of views. It is an indispensable ingredient to explain the puzzle of tiny neutrino masses and the origin of the matter-antimatter asymmetry in our Universe, based on the models in which the simplest Type-I seesaw mechanism can be embedded. The HNL with a mass up to the electroweak scale is an attractive scenario which can be readily tested in present or near-future experiments including the LHC. In this work, we study the decay rates of HNLs and find the sensitive parameter space of the mixing angles between the active neutrinos and HNLs. Since the mixing between ${\nu }_{\tau }$ and HNL is not well established in literature compared with those of ${\nu }_e$ and ${\nu }_{\mu }$ for the HNL of mass in the electroweak scale, we focus on the channel $pp\to W^{\pm (\ast )}+X\to {\tau }^{\pm }N+X$ to search for HNLs at the LHC 14 TeV. The targeted signature consists of three prompt charged leptons, which include at least two tau leptons. After the signal-background analysis, we further set sensitivity bounds on the mixing $|U_{\tau N}{|}^2$ with $M_N$ at High-Luminosity LHC (HL-LHC). We predict the testable bounds from HL-LHC can be stronger than the previous LEP constraints and Electroweak Precision Data (EWPD), especially for $M_N\lesssim$ 50 GeV can reach down to $|U_{\tau N}{|}^2\approx 2\times 10^{-6}$.

   hep-phhep-exPRD(2020)·13 citations
5. 05*

   Axion Model with Intermediate Scale Fermionic Dark Matter

   George Lazarides🇬🇷 · Qaisar Shafi🇺🇸

   We investigate a non-supersymmetric $SO(10)\times U(1{)}_{\mathrm{PQ}}$ axion model in which the spontaneous breaking of $U(1{)}_{\mathrm{PQ}}$ occurs after inflation, and the axion domain wall problem is resolved by employing the Lazarides-Shafi mechanism. This requires the introduction of two fermion 10-plets, such that the surviving discrete symmetry from the explicit $U(1{)}_{\mathrm{PQ}}$ breaking by QCD instantons is reduced from $Z_{12}$ to $Z_4$, where $Z_4$ coincides with the center of $SO(10)$ (more precisely $Spin(10)$). An unbroken $Z_2$ subgroup of $Z_4$ yields intermediate scale topologically stable strings, as well as a stable electroweak doublet non-thermal dark matter candidate from the fermion 10-plets with mass comparable to or somewhat smaller than the axion decay constant $f_{\mathrm{a}}$. We present an explicit realization with inflation taken into account and which also incorporates non-thermal leptogenesis. The fermion dark matter mass lies in the $3\times 10^8-10^{10}\mathrm{GeV}$ range and its contribution to the relic dark matter abundance can be comparable to that from the axion.

   hep-phastro-ph.COPLB(2020)·15 citations
6. 06*

   On a mechanism realizing quark mass hierarchy

   Yoshiharu Kawamura🇯🇵

   We reconsider a generation of up-type quark mass hierarchy in the standard model and clarify how a mechanism works to realize the hierarchy without severe fine tuning.

   hep-phMod.Phys.Lett.A(2020)·0 citations
7. 07*

   Chiral anomaly role in ${\pi }_1(1600)\to \pi {\eta }^{\prime }$

   Francesco Giacosa🇵🇱

   The ground-state (lightest) hybrid nonet with exotic quantum numbers $J^{PC}=1^{-+}$ and the nonet of their chiral partners with $J^{PC}=1^{+-}$ build a homochiral multiplet involving left- and right-handed currents, which under chiral transformation change just as (axial-)vector mesons. Masses and interactions of hybrids can be obtained in the context of the extended Linear Sigma Model. Here, we concentrate on the decays oh hybrids into two pseudoscalar mesons, such as $\eta \pi$ and ${\eta }^{\prime }\pi$ modes. Indeed, ${\pi }_1(1400)\to \pi \eta$ and ${\pi }_1(1600)\to \pi {\eta }^{\prime }$ have been seen in experiments. Assuming that ${\pi }_1(1400)$ and ${\pi }_1(1600)$ correspond to the same state ${\pi }_1^{hyb}$, we show that these decays (and similar ones) follow from a chirally symmetric interaction term that breaks explicitly the axial anomaly. In this respect, these decays would be an additional manifestation of the axial (or chiral) anomaly in the mesonic sector.

   hep-phActa Phys.Polon.Supp.(2021)·0 citations
8. 08*

   QCD axion and topological susceptibility in chiral effective Lagrangian models at finite temperature

   Salvatore Bottaro🇮🇹 · Enrico Meggiolaro🇮🇹

   In this work we compute the axion mass and, from this (exploiting a well-known relation), we also derive an expression for the QCD topological susceptibility in the finite-temperature case, both below and above the chiral phase transition at $T_c$, making use of a chiral effective Lagrangian model which includes the axion, the scalar and pseudoscalar mesons and implements the $U(1)$ axial anomaly of the fundamental theory. We also provide a numerical estimate of the topological susceptibility at $T=0$ (in the physical case of three light quark flavors) and discuss the question of the temperature and quark-mass dependence of the topological susceptibility in the high-temperature regime.

   hep-phhep-lathep-thPRD(2020)·12 citations
9. 09*

   The Fully-Differential Gluon Beam Function at NNLO

   Jonathan R. Gaunt🇨🇭 · Maximilian Stahlhofen🇩🇪

   The fully-differential beam function (dBF) is a universal ingredient in resummed predictions of hadron collider observables that probe the full kinematics of the incoming parton from each colliding proton -- the virtuality and transverse momentum as well as the light-cone momentum fraction $x$. In this paper we compute the matching coefficients between the unpolarized gluon dBF and the usual parton distribution functions (PDFs) at the two-loop order. For observables probing both the virtuality and transverse momentum of incoming gluons, our results provide the part of the NNLO singular cross section related to collinear initial-state radiation, and are required for the resummation of large logarithms through N${}^3$LL. Further to this, the dBF is closely linked to the beam function appearing in a generalized version of threshold factorization, via a simple integration. By performing this integration for the two-loop gluon matching coefficients, we also obtain the corresponding quantities for the generalized threshold beam function.

   hep-phJHEP(2020)·13 citations
10. 10*

    Longitudinal dependence of B and D meson nuclear modifications in heavy-ion collisions at RHIC and the LHC

    Caio A. G. Prado🇨🇳 · Wen-Jing Xing🇨🇳 · Shanshan Cao🇺🇸 · Guang-You Qin🇨🇳 · Xin-Nian Wang🇨🇳

    It is widely acknowledged that heavy flavor probes are sensitive to the properties of the quark-gluon plasma and are often considered an important tool for the plasma tomography studies. Forward rapidity observables can provide further insight on the dynamics of the medium due to the interplay between the medium size and the differences in the production spectra of heavy quark probes. In this proceedings we present the nuclear modification factor $R_{\text{AA}}$'s for B and D mesons, as well as heavy flavor leptons, in the rapidity range $-4.0<y<4.0$ obtained from relativistic Langevin equation with gluon radiation coupled with a (3+1)-dimensional viscous hydrodynamics medium background. We present comparison with experimental data at mid-rapidity as well as predictions for different rapidity ranges.

    ↳ nucl-thhep-phnucl-exNPA(2021)·1 citation
11. 11*

    Beam energy dependence of cumulants of the net-baryon, net-charge and deuteron multiplicity distributions in Au+Au collisions at $\sqrt{s_{NN}}=3.0-5.0$ GeV

    Yunxiao Ye🇨🇳 · Yongjia Wang🇨🇳 · Qingfeng Li🇨🇳 · Dinghui Lu🇨🇳 · Fuqiang Wang🇺🇸

    Within the ultra-relativistic quantum molecular dynamics (UrQMD) model, in which the Lorentz-covariant treatment of nuclear mean-field potential is considered, the fluctuations of net-baryon, net-charge and deuterons multiplicity distributions in Au+Au head-on collisions at $\sqrt{s_{NN}}=3.0-5.0$ GeV are calculated. The results show that the nuclear mean-field potential can significantly enhance the magnitude of baryon number fluctuations in narrow rapidity windows, and this enhancement rapidly weakens with increasing beam energy. However, for proton and net-charge number fluctuations, the mean-field effects are less noticeable than that for baryon number. In addition, for net-charge number fluctuations, the negative binomial distribution agrees well with the calculated results at mid-pseudorapidity window. Finally, the event-by-event fluctuations of deuteron number in the coalescence production picture are calculated as well, it is found that its cumulant ratios decrease linearly with increasing the average multiplicity of deuterons per event, i.e., increase with increasing beam energy.

    ↳ nucl-thhep-phnucl-exPRC(2020)·10 citations
12. 12*

    Chiral torsional effect with finite temperature, density and curvature

    Shota Imaki🇯🇵 · Zebin Qiu🇯🇵

    We scrutinize the novel chiral transport phenomenon driven by spacetime torsion, namely the chiral torsional effect (CTE). We calculate the torsion-induced chiral currents with finite temperature, density and curvature in the most general torsional gravity theory. The conclusion complements the previous study on the CTE by including curvature and substantiates the relation between the CTE and the Nieh-Yan anomaly. We also analyze the response of chiral torsional current to an external electromagnetic field. The resulting topological current is analogous to that in the axion electrodynamics.

    ↳ hep-thgr-qchep-phPRD(2020)·29 citations
13. 13*

    Are $N\bar{\Omega }$ bound states?

    Hongxia Huang🇨🇳 · Xinmei Zhu🇨🇳 · Jialun Ping🇨🇳 · Fan Wang🇨🇳 · T. Goldman🇺🇸

    Inspired by the progress of the experimental search of the $N\Omega$ dibaryon by the STAR collaboration, we study $N\bar{\Omega }$ systems in the framework of quark delocalization color screening model. Our results show that the attraction between $N$ and $\bar{\Omega }$ is a little bit larger than that between $N$ and $\Omega$, which indicates that it is more possible for the $N\bar{\Omega }$ than the $N\Omega$ system to form bound states. The dynamic calculations state that both the $J^P=1^{+}$ and $2^{+}$ $N\bar{\Omega }$ systems are bound states. The binding energy of these two states are deeper than that of $N\Omega$ systems with $J^P=2^{+}$, and the $N\Omega$ system with $J^P=1^{+}$ is unbound. The calculation of the low-energy scattering phase shifts, scattering length and the effective range also supports the existence of the $N\bar{\Omega }$ bound states with $J^P=1^{+}$ and $2^{+}$. So the $N\bar{\Omega }$ states are better hexaquark states and stronger signals are expected in experiments.

    ↳ nucl-thhep-ph2 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.