Fri·Aug 2, 2019Friday·August 2, 2019

1. 01*

   QCD analysis of CMS W + charm measurements at LHC with \sqrt s = 7TeV and implications for the strange PDF

   Nijat Yalkun🇨🇳 · Sayipjamal Dulat🇨🇳

   We calculate cross-sections and cross-section ratios of a charm quark production in association with a $W$ gauge boson at next-to-leading order QCD using MadGraph and CT10NNLO, CT14NNLO, and MSTW2008NNLO PDFs. We compare the results with measurements from the CMS detector at the LHC at a center-of-mass energy of 7TeV. Moreover, we calculate absolute and normalized differential cross-sections as well as differential cross-section ratios as a function of the lepton pseudorapidity from the $W$ boson decay. The correlation between the CT14NNLO PDFs and predictions for $W+$ charm data are studied as well. Furthermore, by employing the error PDF updating method proposed by the CTEQ-TEA group, we update CT14NNLO PDFs, and analyze the impact of CMS 7TeV $W+$ charm production data to the original CT14NNLO PDFs. By comparison of the $g(x,Q)$, $s(x,Q)$, $u(x,Q)$, $d(x,Q)$, $\bar{u}(x,Q)$, and $\bar{d}(x,Q)$ PDFs at $Q=1.3$ GeV and $Q=100$ GeV for the CT14NNLO and CT14NNLO+Wc, we see that the error band of the $s(x,Q)$ PDF is reduced in the region $x<0.4$, and the error band of $g(x,Q)$ PDF is also slightly reduced in the region $0.01<x<0.1$.

   hep-phCPC(2019)·8 citations
2. 02*

   Novel Method for the Precise Determination of the QCD Running Coupling from Event Shapes Distributions in Electron-Positron Annihilation

   Sheng-Quan Wang🇨🇳 · Stanley J. Brodsky🇺🇸 · Xing-Gang Wu🇨🇳 · Jian-Ming Shen🇨🇳 · Leonardo Di Giustino🇺🇸

   We present a novel method for precisely determining the running QCD coupling constant ${\alpha }_s(Q^2)$ over a wide range of $Q^2$ from event shapes for electron-positron annihilation measured at a single annihilation energy $\sqrt{s}$. The renormalization scale $Q^2$ of the running coupling depends dynamically on the virtuality of the underlying quark and gluon subprocess and thus the specific kinematics of each event. The determination of the renormalization scale for event shape distributions is obtained by using the Principle of Maximum Conformality (PMC), a rigorous scale-setting method for gauge theories which satisfies all the requirements of Renormalization Group Invariance, including renormalization-scheme independence and consistency with Abelian theory in the $N_C\to 0$ limit. In this paper we apply the PMC to two classic event shapes measured in $e^{+}{e}^{-}$ annihilation: the thrust ($T$) and C-parameter ($C$). The PMC renormalization scale depends differentially on the values of $T$ and $C$. The application of PMC scale-setting determines the running coupling ${\alpha }_s(Q^2)$ to high precision over a wide range of $Q^2$ from $10$ to $250{\mathrm{GeV}}^2$ from measurements of the event shape distributions at the $Z^0$ peak. The extrapolation of the running coupling using pQCD evolution gives the value ${\alpha }_s(M_Z^2)=0.1185\pm 0.0012$ from the thrust, and ${\alpha }_s(M_Z^2)=0.1193_{-0.0019}^{+0.0021}$ from the C-parameter in the $\overline{\mathrm{MS}}$ scheme. These determinations of ${\alpha }_s(M_Z^2)$ are consistent with the world average and are more precise than the values obtained from analyses of event shapes currently used in the world average. The highly-consistent results for the $T$ and $C$ event-shape distributions provide an additional verification of the applicability of the PMC to pQCD.

   hep-phPRD(2019)·27 citations
3. 03*

   Impact of new physics on $B+L$ violation at colliders

   David G. Cerdeno🇬🇧 · Peter Reimitz🇩🇪 · Kazuki Sakurai🇵🇱 · Carlos Tamarit🇩🇪

   In the Standard Model, chiral electroweak anomalies predict nonperturbative interactions that violate baryon ($B$) plus lepton number ($L$). The potential observability of these processes at colliders has been amply discussed in the literature, mostly focusing on the impact of the accompanying boson emission, which contributes to the cross sections through an exponential function of the center-of-mass energy. We focus instead on the impact of exotic fermions charged under $SU(2{)}_L$, which not only can be emitted in these processes, but also affect the non-exponential contributions to the cross-sections. Estimating the latter using instanton techniques, we find sizable effects that suggest that if $B+L$-violating processes are ever seen at colliders, they may involve physics beyond the Standard Model.

   hep-phhep-thJ.Phys.Conf.Ser.(2020)·3 citations
4. 04*

   Computational challenges for MC event generation

   Andy Buckley🇬🇧

   The sophistication of fully exclusive MC event generation has grown at an extraordinary rate since the start of the LHC era, but has been mirrored by a similarly extraordinary rise in the CPU cost of state-of-the-art MC calculations. The reliance of experimental analyses on these calculations raises the disturbing spectre of MC computations being a leading limitation on the physics impact of the HL-LHC, with MC trends showing more signs of further cost-increases rather than the desired speed-ups. I review the methods and bottlenecks in MC computation, and areas where new computing architectures, machine-learning methods, and social structures may help to avert calamity.

   hep-phhep-exJ.Phys.Conf.Ser.(2020)·29 citations
5. 05*

   Unification for the Darkly Charged Dark Matter

   Ayuki Kamada🇰🇷 · Masaki Yamada🇺🇸 · Tsutomu T. Yanagida🇯🇵

   We provide a simple UV theory for a Dirac dark matter with a massless Abelian gauge boson. We introduce a single fermion transforming as the $16$ representation in the SO(10)${}^{\prime }$ gauge group, which is assumed to be spontaneously broken to SU(5)${}^{\prime }\times$U(1)${}^{\prime }$. The SU(5)${}^{\prime }$ gauge interaction becomes strong at an intermediate scale and then we obtain a light composite Dirac fermion with U(1)${}^{\prime }$ gauge interaction at the low-energy scale. Its thermal relic can explain the observed amount of dark matter consistently with other cosmological and astrophysical constraints. We discuss that a nonzero kinetic mixing between the U(1)${}^{\prime }$ gauge boson and the Hypercharge gauge boson is allowed and the temperature of the visible sector and the dark matter sector can be equal to each other.

   hep-phastro-ph.COPRD(2020)·12 citations
6. 06*

   Canonical interpretation of the newly observed ${\Lambda }_b(6146{)}^0$ and ${\Lambda }_b(6152{)}^0$ via strong decay behaviors

   Wei Liang🇨🇳 · Qi-Fang Lü🇨🇳 · Xian-Hui Zhong🇨🇳

   Stimulated by the newly observed ${\Lambda }_b(6146{)}^0$ and ${\Lambda }_b(6152{)}^0$ resonances, we investigate the strong decays of the low-lying singly bottom baryons within the quark pair creation model. Considering their masses and decay modes, we tentatively assign these states as the $\lambda -$ mode ${\Lambda }_b(2S)$, ${\Lambda }_b(1D)$, ${\Sigma }_b(2S)$, and ${\Sigma }_b(1P)$ states, and then estimate their strong decay widths. Compared with the experimental total widths and decay modes measured by the LHCb Collaboration, the ${\Lambda }_b(6146{)}^0$ and ${\Lambda }_b(6152{)}^0$ can be reasonably clarified into the $J^P=5/2^{+}$ and $J^P=3/2^{+}$ ${\Lambda }_b(1D)$ sates respectively, while other canonical assignments are disfavored. Other low-lying bottom states are also presented, where various narrow states may have good potential to be observed in future LHCb experiments.

   hep-phhep-exnucl-thPRD(2019)·33 citations
7. 07*

   Flavor Dependent Effects on Rare Weak Decays of $B_c^{\ast }$ and $B_s^{\ast }$ Mesons

   Padmapriya R · Rohit Dhir🇯🇵

   We investigate the effects of flavor dependence on the rare weak decays of $B_c^{\ast }$ and $B_s^{\ast }$ mesons to psuedoscalar and vector mesons in the final state. We use the Bauer-Stech-Wirbel model framework to calculate the flavor dependent effects of transverse quark momentum on the form factors and consequently, the branching ratios of Cabibbo-Kobayashi-Maskawa favored and suppressed modes by employing the factorization hypothesis. We find that the flavor dependent effects significantly enhance the form factors and, consequently, the branching ratios. Some of the decay channels in $B_c^{\ast }$ and $B_s^{\ast }$ have branching ratios $\mathcal{O}(10^{-5})$ to $\mathcal{O}(10^{-7})$, which are well within the reach of current experiments.

   hep-ph3 citations
8. 08*

   The Heavy Fermion Contributions to the Massive Three Loop Form Factors

   J. Blümlein🇩🇪 · P. Marquard🇩🇪 · N. Rana🇩🇪 · C. Schneider🇦🇹

   We compute the $n_h$ terms to the massive three loop vector-, axialvector-, scalar- and pseudoscalar form factors in a direct analytic calculation using the method of large moments. This method has the advantage, that the master integrals have to be dealt with only in their moment representation, allowing to also consider quantities which obey differential equations, which are not first order factorizable (elliptic and higher), already at this level. To obtain all the associated recursions, up to 8000 moments had to be calculated. A new technique has been applied to solve the associated differential equation systems. Here the decoupling is performed such, that only minimal depth $ϵ$--expansions had to be performed for non--first-order factorizing systems, minimizing the calculation of initial values. The pole terms in the dimensional parameter $ϵ$ can be completely predicted using renormalization group methods, as confirmed by the present results. A series of contributions at $O({ϵ}^0)$ have first order factorizable representations. For a smaller number of color--zeta projections this is not the case. All first order factorizing terms can be represented by harmonic polylogarithms. We also obtain analytic results for the non--first-order factorizing terms by Taylor series in a variable $x$, for which we have calculated at least 2000 expansion coefficients, in an approximation. Based on this representation the form factors can be given in the Euclidean region and in the region $q^2\approx 0$. Numerical results are presented.

   hep-phNPB(2019)·44 citations
9. 09*

   Probing sterile neutrino in $B$ ($D$) meson decays at Belle II (BESIII)

   C. S. Kim🇰🇷 · Youngjoon Kwon🇰🇷 · Donghun Lee🇰🇷 · Sechul Oh🇰🇷 · Dibyakrupa Sahoo🇰🇷

   We present, how a systematic study of $B\to D\ell N$ ($D\to K\ell N$) decays with $\ell =\mu ,\tau$, at Belle II (BESIII) can provide unambiguous signature of a heavy neutrino $N$ and/or constrain its mixing with active neutrinos ${\nu }_{\ell }$, which is parameterized by $|U_{\ell N}{|}^2$. Our constraint on $|U_{\mu N}{|}^2$ that can be achieved from the full Belle II data is comparable with what can be obtained from the much larger data set of the upgraded LHCb. Additionally, our method offers better constraint on $|U_{\mu N}{|}^2$ for mass of sterile neutrino $m_N<2$ GeV. We can also probe the Dirac and Majorana nature of $N$ by observing the sequential decay of $N$, including suppression from observation of a displaced vertex as well as helicity flip, for Majorana $N$.

   hep-phEPJC(2020)·17 citations
10. 10*

    Charged Higgs searches in the Georgi-Machacek model at the LHC

    Nivedita Ghosh🇮🇳 · Swagata Ghosh🇮🇳 · Ipsita Saha🇯🇵

    The Georgi-Machacek Model allows for a large triplet vacuum expectation value (vev) with a custodial symmetric scalar potential. This manifestly leads to large charged Higgs coupling to SM fermions thus enhancing the detection probability of the model at the Large hadron collider. We show that the latest bound from LHC searches on singly charged Higgs scalar decaying to top and bottom quark restricts the triplet vev from above. We demonstrate that the combined limit from theoretical constraints and the latest Higgs data together with this charged Higgs bound can already curb the model parameter space significantly. Further, we propose the charged Higgs decaying to $W^{\pm }$ boson and a SM-like Higgs as a prospective channel to probe the yet unbounded model parameter space at the future run of the LHC. A simple cut-based analysis for this channel has been made showing the parameter region that can be probed with $5\sigma$ significance at the high luminosity LHC run.

    hep-phPRD(2020)·30 citations
11. 11*

    Isospin-Violating Dark Matter in the $U(1{)}^{\prime }$ Model with $E_6$ Origin

    Tianjun Li🇨🇳 · Qian-Fei Xiang🇨🇳 · Qi-Shu Yan🇨🇳 · Xianhui Zhang🇨🇳 · Han Zhou🇨🇳

    We propose a $U(1{)}^{\prime }$ model from $E_6$ which has an isospin-violation dark matter. By choosing a proper linear combination of two extra $U(1)$ gauge symmetries in $E_6$, it is natural to realize the ratio $f_n/f_p=-0.7$ so as to maximally relax the constraints from the Xenon based direct detection experiments. We study the sensitivities of the dark matter direct and indirect detection experiments, and identify the parameter spaces that can give the observed relic density. We also study the sensitivities of the future colliders with center mass energy $\sqrt{s}$= 33/50/100 TeV, and compare the different detection methods. We show that in some parameter spaces the future colliders can give much stronger limits.

    hep-phPRD(2020)·6 citations
12. 12*

    Deconfinement and freezeout boundaries in equilibrium thermal models

    Abdel Nasser Tawfik (Nile U., ECTP and Johann Wolfgang Goethe-Universitat)🇪🇬 · Muhammad Maher🇪🇬 · A. H. El-Kateb🇪🇬 · Sara Abdelaziz (Helwan U)🇪🇬

    In different approaches, the temperature-baryon density plane of QCD matter is studied for deconfinement and chemical freezeout boundaries. Results from various heavy-ion experiments are compared with the recent lattice simulations, the effective QCD-like Polyakov linear-sigma model, and the equilibrium thermal models. Along the entire freezeout boundary, there is an excellent agreement between the thermal model calculations and the experiments. Also, the thermal model calculations agree well with the estimations deduced from the Polyakov linear-sigma model (PLSM). At low baryonic density or high energies, both deconfinement and chemical freezeout boundaries are likely coincident and therefore the agreement with the lattice simulations becomes excellent as well, while at large baryonic density, the two boundaries become distinguishable forming a phase where hadrons and quark-gluon plasma likely coexist.

    hep-phAdv.High Energy Phys.(2020)·3 citations
13. 13*

    Azimuthal asymmetries in semi-inclusive $J/\psi +\mathrm{jet}$ production at an EIC

    Umberto D'Alesio🇮🇹 · Francesco Murgia🇮🇹 · Cristian Pisano🇮🇹 · Pieter Taels🇮🇹

    We consider transverse momentum dependent gluon distributions inside both unpolarized and transversely polarized protons and show how they can be probed by looking at azimuthal modulations in $ep\to eJ/\psi \mathrm{jet}X$. We find that the contribution due to quark induced subprocesses is always suppressed in the considered kinematic regions, accessible in principle at a future Electron-Ion Collider. Our model-independent estimates of the maximal values of these asymmetries allowed by positivity bounds suggest the feasibility of their measurement. In addition, by adopting the McLerran-Venugopalan model for the unpolarized and linearly polarized gluon densities, we study the behavior of the $\cos 2\varphi$ asymmetries in the small-$x$ limit.

    hep-phPRD(2019)·77 citations
14. 14*

    Density matrix calculation of the dark matter abundance in the Higgs induced right-handed neutrino mixing model

    P. Di Bari🇬🇧 · K. Farrag🇬🇧 · R. Samanta🇬🇧 · Y.L. Zhou🇬🇧

    We present new results on the calculation of the dark matter relic abundance within the Higgs induced right-handed (RH) neutrino mixing model, solving the associated density matrix equation. For a benchmark value of the dark matter mass $M_{\mathrm{DM}}=220\mathrm{TeV}$, we show the evolution of the abundance and how this depends on reheat temperature, dark matter lifetime and source RH neutrino mass $M_{\mathrm{S}}$, with the assumption $M_{\mathrm{S}}<M_{\mathrm{DM}}$. We compare the results with those obtained within the Landau-Zener approximation, showing that the latter largely overestimates the final abundance giving some analytical insight. However, we also notice that since in the density matrix formalism the production is non-resonant, this allows source RH neutrino masses below the W boson mass, making dark matter more stable at large mass values. This opens an allowed region for initial vanishing source RH neutrino abundance. For example, for $M_{\mathrm{S}}\gtrsim 1\mathrm{GeV}$, we find $M_{\mathrm{DM}}\gtrsim 20\mathrm{PeV}$. Otherwise, for $M_{\mathrm{S}}>M_W\sim 100\mathrm{GeV}$, one has to assume a thermalisation of the source RH neutrinos prior to the freeze-in of the dark matter abundance. This results into a large allowed range for $M_{\mathrm{DM}}$, depending on $M_{\mathrm{S}}$. For example, imposing $M_{\mathrm{S}}\gtrsim 300\mathrm{GeV}$, allowing also successful leptogenesis, we find $0.5\lesssim M_{\mathrm{DM}}/\mathrm{TeV}\lesssim 500$. We also discuss in detail leptogenesis with two quasi-degenerate RH neutrinos, showing a case when observed dark matter abundance and matter-antimatter asymmetry are simultaneously reproduced. Finally, we comment on how an initial thermal source RH neutrino abundance can be justified and on how our results suggest that also the interesting case where $M_{\mathrm{DM}}<M_{\mathrm{S}}$, embeddable in usual high scale two RH neutrino seesaw models, might be viable.

    hep-phJCAP(2020)·18 citations
15. 15*

    Indirect Detection of Composite (Asymmetric) Dark Matter

    Rakhi Mahbubani🇨🇭 · Michele Redi🇮🇹 · Andrea Tesi🇮🇹

    Dark Matter can form bound states upon the emission of quanta of energy equal to the binding energy. The rate of this process is large for strongly-interacting Dark Matter, and further enhanced by long distance effects. The resulting monochromatic and diffuse $\gamma$-rays can be tested in indirect detection experiments. If Dark Matter has electroweak charge, indirect signals include multiple observable photon lines for masses in the TeV range. Else if it couples only via a dark photon portal, diffuse spectra from dwarf galaxies and CMB reionization set powerful limits for masses below a TeV. This mechanism provides a powerful means of probing Asymmetric Dark Matter today.

    hep-phastro-ph.COhep-latnucl-thPRD(2020)·26 citations
16. 16*

    Stellar probes of dark sector-photon interactions

    Xiaoyong Chu🇦🇹 · Jui-Lin Kuo🇦🇹 · Josef Pradler🇦🇹 · Lukas Semmelrock🇦🇹

    Electromagnetically neutral dark sector particles may directly couple to the photon through higher dimensional effective operators. Considering electric and magnetic dipole moment, anapole moment, and charge radius interactions, we derive constraints from stellar energy loss in the Sun, horizontal branch and red giant stars, as well as from cooling of the proto-neutron star of SN1987A. We provide the exact formula for in-medium photon-mediated pair production to leading order in the dark coupling, and compute the energy loss rates explicitly for the most important processes, including a careful discussion on resonances and potential double counting between the processes. Stringent limits for dark states with masses below $3$keV ($40$MeV) arise from red giant stars (SN1987A), implying an effective lower mass-scale of approximately $10^9$GeV ($10^7$GeV) for mass-dimension five, and $100$GeV ($2.5$TeV) for mass-dimension six operators as long as dark states stream freely; for the proto-neutron star, the trapping of dark states is also evaluated. Together with direct limits previously derived by us in Chu et al. (2018), this provides the first comprehensive overview of the viability of effective electromagnetic dark-state interactions below the GeV mass-scale.

    hep-phastro-ph.HEPRD(2019)·48 citations
17. 17*

    GRB lensing parallax: Closing primordial black hole dark matter mass window

    Sunghoon Jung🇰🇷 · TaeHun Kim🇰🇷

    The primordial black hole (PBH) comprising full dark matter (DM) abundance is currently allowed if its mass lies between $10^{-16}{M}_{\odot }\lesssim M\lesssim 10^{-11}{M}_{\odot }$. This lightest mass range is hard to be probed by ongoing gravitational lensing observations. In this paper, we advocate that an old idea of the lensing parallax of Gamma-ray bursts (GRBs), observed simultaneously by spatially separated detectors, can probe the unconstrained mass range; and that of nearby stars can probe a heavier mass range. In addition to various good properties of GRBs, astrophysical separations achievable around us --- $r_{\oplus }\text{–}$ AU --- is just large enough to resolve the GRB lensing by lightest PBH DM.

    ↳ astro-ph.COgr-qchep-phPRResearch(2020)·52 citations
18. 18*

    Centrality Dependence of Multiplicity Fluctuations in Ion-Ion Collisions from the Beam Energy Scan at FAIR

    Anuj Chandra🇮🇳 · Bushra Ali🇮🇳 · Shakeel Ahmad🇮🇳

    Multiplicity distributions and event-by-event multiplicity fluctuations in AuAu collisions at energies in future heavy-ion experiment at the Facility for Anti-proton and Ion Research (FAIR) are investigated. Events corresponding to FAIR energies are simulated in the frame work of Ultra Relativistic Quantum Molecular Dynamics (URQMD) model. It is observed that the mean and the width of multiplicity distributions monotonically increase with beam energy. The trend of variations of dispersion with mean number of participating nucleons for the centrality-bin width of 5\% are in accord with the Central Limit Theorem. The multiplicity distributions in various centrality bins as well as for full event samples are observed to obey Koba, Nielsen and Olesen (KNO) scaling. The trends of variations of scaled variance with beam energy are also found to support the KNO scaling predictions for larger collision centrality. The findings also reveal that the statistical fluctuations in 5\% centrality-bin width appear to be under control.

    ↳ nucl-thhep-phAdv.High Energy Phys.(2019)·3 citations
19. 19*

    Constraining graviton non-Gaussianity through the CMB bispectra

    Valerio De Luca🇨🇭 · Gabriele Franciolini🇨🇭 · Alex Kehagias🇬🇷 · Antonio Riotto🇨🇭 · Maresuke Shiraishi🇯🇵

    Tensor non-Gaussianities are a key ingredient to test the symmetries and the presence of higher spin fields during the inflationary epoch. Indeed, the shape of the three point correlator of the graviton is totally fixed by the symmetries of the de Sitter stage and, in the case of parity conservation, gets contributions only from the ordinary gravity action plus a higher derivative term called the (Weyl)${}^3$ action. We discuss current and future bounds on the three point tensor contribution from the (Weyl)${}^3$ term using cosmic microwave background (CMB) bispectra. Our results indicate that forthcoming experiments, such as LiteBIRD, CMB-S4 and CORE, will detect the presence of the (Weyl)${}^3$ term if $M_p^4{L}^4\sim 10^{17}{r}^{-4}$, where $L$ parametrizes the strength of the (Weyl)${}^3$ term and $r$ is the tensor-to-scalar ratio, which corresponds to $L\gtrsim 3.2\times 10^5{M}_p^{-1}$, while the current upper limit is $M_p^4{L}^4=(1.1\pm 4.0)\times 10^{19}{r}^{-4}$ (68%CL).

    ↳ astro-ph.COgr-qchep-phPRD(2019)·10 citations
20. 20*

    Infrared renormalon in the supersymmetric $\mathbb{C}{P}^{N-1}$ model on $\mathbb{R}\times S^1$

    Kosuke Ishikawa🇯🇵 · Okuto Morikawa🇯🇵 · Akira Nakayama🇯🇵 · Kazuya Shibata🇯🇵 · Hiroshi Suzuki🇯🇵 · Hiromasa Takaura🇯🇵

    In the leading order of the large-$N$ approximation, we study the renormalon ambiguity in the gluon (or, more appropriately, photon) condensate in the 2D supersymmetric $\mathbb{C}{P}^{N-1}$ model on~$\mathbb{R}\times S^1$ with the ${\mathbb{Z}}_N$ twisted boundary conditions. In our large~$N$ limit, the combination $\Lambda R$, where $\Lambda$ is the dynamical scale and $R$~is the $S^1$ radius, is kept fixed (we set $\Lambda R\ll 1$ so that the perturbative expansion with respect to the coupling constant at the mass scale~$1/R$ is meaningful). We extract the perturbative part from the large-$N$ expression of the gluon condensate and obtain the corresponding Borel transform~$B(u)$. For~$\mathbb{R}\times S^1$, we find that the Borel singularity at~$u=2$, which exists in the system on the uncompactified~${\mathbb{R}}^2$ and corresponds to twice the minimal bion action, disappears. Instead, an unfamiliar renormalon singularity \emph{emerges\/} at~$u=3/2$ for the compactified space~$\mathbb{R}\times S^1$. The semi-classical interpretation of this peculiar singularity is not clear because $u=3/2$ is not dividable by the minimal bion action. It appears that our observation for the system on~$\mathbb{R}\times S^1$ prompts reconsideration on the semi-classical bion picture of the infrared renormalon.

    ↳ hep-thhep-lathep-phPTEP(2020)·26 citations
21. 21*

    Chiral Magnetic Josephson junction: a base for low-noise superconducting qubits?

    M. N. Chernodub🇫🇷 · J. Garaud🇫🇷 · D. E. Kharzeev🇺🇸

    Superconducting materials with non-centrosymmetric lattices lacking the space inversion symmetry are known to exhibit a variety of interesting parity-breaking phenomena, including the anomalous Josephson effect. Here we consider a Josephson junction consisting of two non-centrosymmetric superconductors (NCSs) connected by a uniaxial ferromagnet, and demonstrate that it exhibits a direct analog of the Chiral Magnetic Effect observed in Dirac and Weyl semimetals. We propose to use this "Chiral Magnetic Josephson junction" (CMJ junction) as an element of a qubit with a Hamiltonian tunable by the ferromagnet's magnetization. The CMJ junction allows to avoid the use of an offset magnetic flux in inductively shunted qubits, thus enabling a simpler and more robust architecture. The resulting"`chiral magnetic qubit" is protected from the noise caused by fluctuations in magnetization when the easy axis of the uniaxial ferromagnet is directed across the junction.

    ↳ cond-mat.supr-concond-mat.mes-hallhep-phquant-phUniverse(2022)·6 citations
22. 22*

    PHSD -- a microscopic transport approach for strongly interacting systems

    E.L. Bratkovskaya🇩🇪 · W. Cassing🇩🇪 · P. Moreau🇩🇪 · L. Oliva🇩🇪 · O.E. Soloveva🇩🇪 · T. Song🇩🇪

    We present the basic ideas of the Parton-Hadron-String Dynamics (PHSD) transport approach which is a microscopic covariant dynamical model for strongly interacting systems formulated on the basis of Kadanoff-Baym equations for Green's functions in phase-space representation (in 1st order gradient expansion beyond the quasi-particle approximation). The approach consistently describes the full evolution of a relativistic heavy-ion collision from the initial hard scatterings and string formation through the dynamical deconfinement phase transition to the strongly-interacting quark-gluon plasma (sQGP) as well as hadronization and the subsequent interactions in the expanding hadronic phase. The PHSD approach has been applied to p+p, p+A and A+A collisions from lower SIS to LHC energies and been successful in describing a large number of experimental data including single-particle spectra, collective flow and electromagnetic probes. Some highlights of recent PHSD results will be presented.

    ↳ nucl-thhep-ph14 citations
23. 23*

    Anisotropies and non-Gaussianity of the Cosmological Gravitational Wave Background

    N. Bartolo🇮🇹 · D. Bertacca🇮🇹 · S. Matarrese🇮🇹 · M. Peloso🇮🇹 · A. Ricciardone🇮🇹 · A. Riotto🇨🇭 · G. Tasinato🇬🇧

    The Stochastic Gravitational Wave Background (SGWB) is expected to be a key observable for Gravitational Wave (GW) interferometry. Its detection will open a new window on early universe cosmology and on the astrophysics of compact objects. Using a Boltzmann approach, we study the angular anisotropies of the GW energy density, which is an important tool to disentangle the different cosmological and astrophysical contributions to the SGWB. Anisotropies in the cosmological background are imprinted both at its production, and by GW propagation through the large-scale scalar and tensor perturbations of the universe. The first contribution is not present in the Cosmic Microwave Background (CMB) radiation (as the universe is not transparent to photons before recombination), causing an order one dependence of the anisotropies on frequency. Moreover, we provide a new method to characterize the cosmological SGWB through its possible deviation from a Gaussian statistics. In particular, the SGWB will become a new probe of the primordial non-Gaussianity of the large-scale cosmological perturbations.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2019)·142 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.