Wed·Aug 14, 2019Wednesday·August 14, 2019

1. 01*

   From Non-interacting to Interacting Picture of Thermodynamics and Transport Coefficients for Quark Gluon Plasma

   Sarthak Satapathy🇮🇳 · Souvik Paul🇮🇳 · Ankit Anand🇮🇳 · Ranjesh Kumar🇮🇳 · Sabyasachi Ghosh🇮🇳

   We have attempted to build first some simplified model to map the interaction of quarks and gluons, which can be contained by their thermodynamical quantity like entropy density, obtained from calculation of lattice quantum chromo dynamics (LQCD). With respect to entropy density of the standard non-interacting massless quark gluon plasma (QGP), its interacting values from LQCD simulation are reduced as we go from higher to lower temperature through the cross-over of quark-hadron phase transition. By parameterizing increasing degeneracy factor or increasing interaction-fugacity or decreasing thermal width of quarks and gluons with temperature, we have matched LQCD data.Using that interaction picture, shear viscosity and electrical conductivity are calculated. For getting nearly perfect fluid nature of QGP, interaction might have some role when we consider temperature dependent thermal width.

   hep-phnucl-thJ.Phys.G(2020)·12 citations
2. 02*

   From Non-interacting to Interacting Picture of Quark Gluon Plasma in presence of magnetic field and its fluid property

   Jayanta Dey🇮🇳 · Sarthak Satapathy🇮🇳 · Ankita Mishra🇮🇳 · Souvik Paul🇮🇳 · Sabyasachi Ghosh🇮🇳

   We have attempted to build a parametric based simplified and analytical model to map the interaction of quarks and gluons in presence of magnetic field, which has been constrained by quark condensate and thermodynamical quantities like pressure, energy density etc., obtained from the calculation of lattice quantum chromodynamics. To fulfill that mapping, we have assumed a parametric temperature and magnetic field dependent degeneracy factor, average energy, momentum and velocity of quarks and gluons. Implementing this QCD interaction in calculation of transport coefficient at finite magnetic field, we have noticed that magnetic field and interaction both are two dominating sources, for which the values of transport coefficients can be reduced. Though the methodology is not so robust, but with the help of its simple parametric expressions, one can get a quick rough estimation of any phenomenological quantity, influenced by temperature and magnetic field dependent QCD interaction.

   hep-phnucl-thIJMPE(2021)·40 citations
3. 03*

   Hidden charm pentaquarks with color-octet substructure in QCD Sum Rules

   Alexandr Pimikov🇨🇳 · Hee-Jung Lee🇰🇷 · Pengming Zhang🇨🇳

   We study the hidden-charm pentaquark states $udsc\bar{c}$ with spins 1/2, 3/2, and 5/2 within the QCD sum-rule approach. First, we construct the currents for the particular configuration of pentaquark states that consist of the flavor singlet three-quark cluster $uds$ of spins 1/2 and 3/2 and the two-quark cluster $\bar{c}c$ of spin 1, where both clusters are in a color-octet state. From the QCD sum rules obtained by the operator product expansion up to dimension-10 condensates, the extracted masses for the pentaquark states $uds$-$\bar{c}c$ are about 4.6 GeV (5.6 GeV) for spin 1/2${}^{\pm }$, about 5.1 GeV (6.0 GeV) for spin 3/2${}^{\pm }$, about 6.1 GeV (5.9 GeV) for spin 5/2${}^{\pm }$, where the masses of the positive parity states are given in parentheses. Additionally, based on the flavor singlet pentaquark states, it is also shown that other pentaquark states of clusters like $udc$-$\bar{c}s$ and $usc$-$\bar{c}d$ lead to masses similar to the $uds$-$\bar{c}c$ case within error bars. Furthermore, in order to see whether any of the states, observed by the LHCb Collaboration, could be understood as the pentaquark of two clusters in the color-octet state, we study the pentaquark formed by the two clusters $udc$-$\bar{c}u$, where the three-quark cluster is assumed to have the same flavor structure as the above $uds$ cluster. We come to the conclusion that if the observed pentaquark will be found to have spin 1/2 and negative parity, then it could be described as a state of two color-octet clusters.

   hep-phhep-exPRD(2020)·44 citations
4. 04*

   Interpretation of the newly observed ${\Lambda }_b(6146{)}^0$ and ${\Lambda }_b(6152{)}^0$ states in a chiral quark model

   Kai-Lei Wang🇨🇳 · Qi-Fang Lü🇨🇳 · Xian-Hui Zhong🇨🇳

   The strong decays of the low-lying $\lambda$-mode ${\Lambda }_b(1D,2S)$ and ${\Sigma }_b(2S)$ states are studied in a chiral quark model. We find that: (i) the newly observed ${\Lambda }_b(6146/6152)$ resonances in the ${\Lambda }_b{\pi }^{+}{\pi }^{-}$ spectrum by the LHCb Collaboration might be explained with the $\lambda$-mode ${\Lambda }_b(1D)$ states in the quark model. It should be emphasized that whether the structure in the ${\Lambda }_b{\pi }^{+}{\pi }^{-}$ spectrum correspond to two states or one state should be further clarified with more observations in future experiments. (ii) The ${\Lambda }_b(2S)$ $|J^P={\frac{1}{2}}^{+},0⟩$ state mainly decays into ${\Sigma }_b^{\ast }\pi$ channel, which may be an ideal channel for searching for this ${\Lambda }_b(2S)$ state in future experiments. (iii) The ${\Sigma }_b(2S)$ $|J^P={\frac{1}{2}}^{+},1⟩$ and $|J^P={\frac{3}{2}}^{+},1⟩$ dominantly decay into ${\Lambda }_b\pi$ with $\Gamma \simeq 3.82$ MeV and $\Gamma \simeq 4.72$ MeV, respectively.

   hep-phPRD(2019)·37 citations
5. 05*

   Light scalar production from Higgs bosons and FASER 2

   Iryna Boiarska🇩🇰 · Kyrylo Bondarenko🇳🇱 · Alexey Boyarsky🇳🇱 · Maksym Ovchynnikov🇳🇱 · Oleg Ruchayskiy🇩🇰 · Anastasia Sokolenko🇳🇴

   The most general renormalizable interaction between the Higgs sector and a new gauge-singlet scalar $S$ is governed by two interaction terms: cubic and quartic. The quartic interaction is only loosely constrained by invisible Higgs decays. Given current experimental limits about $10\%$ of all Higgs bosons created at the LHC can be converted to new scalars with the mass up to $m_{\mathrm{Higgs}}/2$. This can significantly extend the reach of the LHC-based Intensity Frontier experiments. We analyze the sensitivity of the FASER experiment to this model and discuss modest changes in the FASER 2 design that would allow to explore an orders-of-magnitude wider part of the Higgs portal's parameter space.

   hep-phhep-exJHEP(2020)·35 citations
6. 06*

   Mid-rapidity dependence of hadron production in $p-p$ and $A-A$ collisions

   A.I. Malakhov🇷🇺 · G.I. Lykasov🇷🇺

   The calculation of inclusive spectra of pions produced in $pp$ and $AA$ collisions as a function of rapidity $y$ is presented within the self-similarity approach. It is shown that at not large rapidities $y$ one can obtain the analytical form of the self-similarity function $\Pi (y,p_t)$ dependent of $y$ and hadron transverse momentum $p_t$. A satisfactory description of data on the rapidity spectra at $|y|\le$ 0.3 is illustrated within a good agreement. The universal energy dependence of these spectra is also shown.

   hep-phEPJA(2020)·6 citations
7. 07*

   Model-independent method for measuring the angular coefficients of $B^0\to D^{\ast -}{\tau }^{+}{\nu }_{\tau }$ decays

   Donal Hill🇬🇧 · Malcolm John🇬🇧 · Wenqi Ke🇫🇷 · Anton Poluektov🇫🇷

   Reconstruction of the $B^0\to D^{\ast -}{\tau }^{+}{\nu }_{\tau }$ angular distribution is complicated by the strongly-biasing effect of losing the neutrino information from both the $B$ and $\tau$ decays. In this work, a novel method for making unbiased measurements of the angular coefficients while preserving the model independence of the angular technique is demonstrated. The twelve angular functions that describe the signal decay, in addition to background terms, are modelled in a multidimensional fit, using template probability density functions that encapsulate all resolution and acceptance effects. Sensitivities at the LHCb and Belle II experiments are estimated, and sources of systematic uncertainty are discussed, notably in the extrapolation to a measurement of $R(D^{\ast })$.

   hep-phhep-exJHEP(2019)·30 citations
8. 08*

   Inert Doublet Model Signatures at Future e+e- Colliders

   Aleksander Filip Zarnecki🇵🇱 · Jan Kalinowski🇵🇱 · Jan Klamka🇵🇱 · Pawel Sopicki🇵🇱 · Wojciech Kotlarski🇩🇪 · Tania Robens🇭🇷 · Dorota Sokolowska🇧🇷

   The Inert Doublet Model is one of the simplest extensions of the Standard Model, providing a dark matter candidate. It is a two Higgs doublet model with a discrete $Z_2$ symmetry, that prevents the scalars of the second doublet (inert scalars) from coupling to the Standard Model fermions and makes the lightest of them stable. We study a large number of Inert Doublet Model scenarios, which are consistent with current constraints on direct detection, including the most recent bounds from the XENON1T experiment and relic density of dark matter, as well as collider and low-energy limits. We use a set of benchmark points with different kinematic features, that promise detectable signals at future $e^{+}{e}^{-}$ colliders. Two inert scalar pair-production processes are considered, $e^{+}{e}^{-}\to AH$ and $e^{+}{e}^{-}\to H^{+}{H}^{-}$, followed by decays of $H^{\pm }$ and $A$ into the final states which include the lightest and stable neutral scalar dark matter candidate $H$. Significance of the expected observations is studied for different benchmark models and different running scenarios, for centre-of-mass energies up to 3 TeV. Numerical results are presented for the signal signatures with two muons or an electron and a muon in the final state, while the qualitative conclusions can also be drawn for the semi-leptonic signatures.

   hep-phPoS(2020)·7 citations
9. 09*

   Ultralight dark matter detection with mechanical quantum sensors

   Daniel Carney🇺🇸 · Anson Hook🇺🇸 · Zhen Liu🇺🇸 · Jacob M. Taylor🇺🇸 · Yue Zhao🇺🇸

   We consider the use of quantum-limited mechanical force sensors to detect ultralight (sub-meV) dark matter candidates which are weakly coupled to the standard model. We show that mechanical sensors with masses around or below the milligram scale, operating around the standard quantum limit, would enable novel searches for dark matter with natural frequencies around the kHz scale. This would complement existing strategies based on torsion balances, atom interferometers, and atomic clock systems.

   hep-phhep-exquant-phNew J.Phys.(2021)·96 citations
10. 10*

    Hunting for heavy Dark Matter in the Galactic Center with ground-based Cherenkov telescopes

    Lucia Rinchiuso🇫🇷 · Nicholas L. Rodd🇺🇸 · Emmanuel Moulin🇫🇷 · Tracy R. Slatyer🇺🇸

    A TeV scale electroweak particle is a well motivated candidate for the dark matter (DM) of our Universe. Yet such a particle may only be detectable using indirect detection instruments sensitive to TeV-scale gamma rays that can result from dark matter annihilations. We present a mock analysis of the sensitivity for the present ground-based Cherenkov telescope array H.E.S.S. (High Energy Spectroscopic System) to detect TeV scale DM in the Galactic Center region. The work combines next-to-leading-logarithmic order calculations for the annihilation photon spectrum, as well as a comprehensive treatment of detector effects and expected backgrounds. Forecast limits on the sensitivity of H.E.S.S. have been derived across the important TeV mass range, assuming different DM density profiles and focusing on the canonical WIMP dark matter candidate Wino.These limits test our present and future ability to probe the predicted thermal cross section for some of the most promising DM candidates that could be discovered in the coming decade.

    ↳ astro-ph.HEastro-ph.COhep-phPoS(2020)·1 citation
11. 11*

    Conformality Loss, Walking, and 4D Complex Conformal Field Theories at Weak Coupling

    Francesco Benini🇮🇹 · Cristoforo Iossa🇮🇹 · Marco Serone🇮🇹

    Four-dimensional gauge theories with matter can have regions in parameter space, often dubbed conformal windows, where they flow in the infrared to non-trivial conformal field theories. It has been conjectured that conformality can be lost because of merging of two nearby fixed points that move into the complex plane, and that a walking dynamics governed by scaling dimensions of operators defined at such complex fixed points can occur. We find controlled, parametrically weakly coupled, and ultraviolet-complete 4D gauge theories that explicitly realize this scenario. We show how the walking dynamics is controlled by the coupling of a double-trace operator that crosses marginality. The walking regime ends when the renormalization group flow of this coupling leads to a (weak) first-order phase transition with Coleman-Weinberg symmetry breaking. A light dilaton-like scalar particle appears in the spectrum, but it is not parametrically lighter than the other excitations.

    ↳ hep-thhep-phPRL(2020)·48 citations
12. 12*

    Charged particle tracking with quantum annealing-inspired optimization

    Alexander Zlokapa🇺🇸 · Abhishek Anand🇺🇸 · Jean-Roch Vlimant🇺🇸 · Javier M. Duarte🇺🇸 · Joshua Job🇺🇸 · Daniel Lidar🇺🇸 · Maria Spiropulu🇺🇸

    At the High Luminosity Large Hadron Collider (HL-LHC), traditional track reconstruction techniques that are critical for analysis are expected to face challenges due to scaling with track density. Quantum annealing has shown promise in its ability to solve combinatorial optimization problems amidst an ongoing effort to establish evidence of a quantum speedup. As a step towards exploiting such potential speedup, we investigate a track reconstruction approach by adapting the existing geometric Denby-Peterson (Hopfield) network method to the quantum annealing framework and to HL-LHC conditions. Furthermore, we develop additional techniques to embed the problem onto existing and near-term quantum annealing hardware. Results using simulated annealing and quantum annealing with the D-Wave 2X system on the TrackML dataset are presented, demonstrating the successful application of a quantum annealing-inspired algorithm to the track reconstruction challenge. We find that combinatorial optimization problems can effectively reconstruct tracks, suggesting possible applications for fast hardware-specific implementations at the LHC while leaving open the possibility of a quantum speedup for tracking.

    ↳ quant-phcs.LGhep-phQuantum Machine Intelligence(2021)·50 citations
13. 13*

    Quantum adiabatic machine learning with zooming

    Alexander Zlokapa🇺🇸 · Alex Mott🇬🇧 · Joshua Job🇺🇸 · Jean-Roch Vlimant🇺🇸 · Daniel Lidar🇺🇸 · Maria Spiropulu🇺🇸

    Recent work has shown that quantum annealing for machine learning, referred to as QAML, can perform comparably to state-of-the-art machine learning methods with a specific application to Higgs boson classification. We propose QAML-Z, a novel algorithm that iteratively zooms in on a region of the energy surface by mapping the problem to a continuous space and sequentially applying quantum annealing to an augmented set of weak classifiers. Results on a programmable quantum annealer show that QAML-Z matches classical deep neural network performance at small training set sizes and reduces the performance margin between QAML and classical deep neural networks by almost 50% at large training set sizes, as measured by area under the ROC curve. The significant improvement of quantum annealing algorithms for machine learning and the use of a discrete quantum algorithm on a continuous optimization problem both opens a new class of problems that can be solved by quantum annealers and suggests the approach in performance of near-term quantum machine learning towards classical benchmarks.

    ↳ quant-phcs.LGhep-phPRA(2020)·28 citations
14. 14*

    Propagator from Nonperturbative Worldline Dynamics

    Sebastián Franchino-Viñas🇩🇪 · Holger Gies🇩🇪

    We use the worldline representation for correlation functions together with numerical path integral methods to extract nonperturbative information about the propagator to all orders in the coupling in the quenched limit (small-$N_{\text{f}}$ expansion). Specifically, we consider a simple two-scalar field theory with cubic interaction (S${}^2$QED) in four dimensions as a toy model for QED-like theories. Using a worldline regularization technique, we are able to analyze the divergence structure of all-order diagrams and to perform the renormalization of the model nonperturbatively. Our method gives us access to a wide range of couplings and coordinate distances. We compute the pole mass of the S${}^2$QED electron and observe sizable nonperturbative effects in the strong-coupling regime arising from the full photon dressing. We also find indications for the existence of a critical coupling where the photon dressing compensates the bare mass such that the electron mass vanishes. The short distance behavior remains unaffected by the photon dressing in accordance with the power-counting structure of the model.

    ↳ hep-thhep-lathep-phPRD(2019)·14 citations
15. 15*

    Cosmic Textures and Global Monopoles as Seeds for Super-Massive Black Holes

    Robert Brandenberger🇨🇦 · Hao Jiao (McGill, ETH Zuerich and USTC)🇨🇳

    We compute the number density of nonlinear seed fluctuations which have the right number density to be able to explain the presence of one supermassive black hole per galaxy, as a function of redshift. We find that there is an interesting range of symmetry breaking scales for which the density of seeds is larger that what is predicted in the standard cosmological model with Gaussian primordial fluctuations. Hence, global defects may help in light of the mounting tension between the standard cosmological model and observations of supermassive black hole candidates at high redshifts.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2020)·10 citations
16. 16*

    Safety versus triviality on the lattice

    Viljami Leino🇩🇪 · Tobias Rindlisbacher🇫🇮 · Kari Rummukainen🇫🇮 · Francesco Sannino🇩🇰 · Kimmo Tuominen🇫🇮

    We present the first numerical study of the ultraviolet dynamics of non-asymptotically free gauge-fermion theories at large number of matter fields. As testbed theories we consider non-abelian SU(2) gauge theories with 24 and 48 Dirac fermions on the lattice. For these number of flavors asymptotic freedom is lost and the theories are governed by a gaussian fixed point at low energies. In the ultraviolet they can develop a physical cutoff and therefore be trivial, or achieve an interacting safe fixed point and therefore be fundamental at all energy scales. We demonstrate that the gradient flow method can be successfully implemented and applied to determine the renormalized running coupling when asymptotic freedom is lost. Additionally, we prove that our analysis is connected to the gaussian fixed point as our results nicely match with the perturbative beta function. Intriguingly, we observe that it is hard to achieve large values of the renormalized coupling on the lattice. This might be an early sign of the existence of a physical cutoff and imply that a larger number of flavors is needed to achieve the safe fixed point. A more conservative interpretation of the results is that the current lattice action is unable to explore the deep ultraviolet region where safety might emerge. Our work constitutes an essential step towards determining the ultraviolet fate of non asymptotically free gauge theories.

    ↳ hep-lathep-phhep-thPRD(2020)·26 citations
17. 17*

    News on the CLIC physics potential

    Aleksander Filip Zarnecki🇵🇱

    The Compact Linear Collider (CLIC) is a proposed TeV-scale high-luminosity electron-positron collider. For an optimal exploitation of its physics potential, CLIC is foreseen to be built and operated in three stages, with centre-of-mass energies ranging from 380 GeV up to 3 TeV. Electron beam polarisation is provided at all energies. The initial energy stage will focus on precision measurements of Higgs-boson and top-quark properties. The subsequent energy stages enhance the reach of many direct and indirect searches for new physics Beyond the Standard Model (BSM) and give access to the Higgs self-coupling. Higgs and top-quark projections have been evaluated using full detector simulation studies. Many new phenomenology studies have been undertaken to explore the BSM reach of CLIC, from Effective Field Theory (EFT) interpretations of precision measurements through to signature-based searches; these include flavour dynamics, and dark matter and heavy neutrino searches. Selected results that demonstrate the outstanding potential of CLIC in many physics domains are reviewed.

    ↳ hep-exhep-phPoS(2020)·1 citation
18. 18*

    First-order phase transition from hypernuclear matter to deconfined quark matter obeying new constraints from compact star observations

    M. Shahrbaf🇮🇷 · D. Blaschke🇵🇱 · A. G. Grunfeld🇦🇷 · H. R. Moshfegh🇮🇷

    We reconsider the problem of the hyperon puzzle and its suggested solution by quark deconfinement within the two-phase approach to hybrid compact stars with recently obtained hadronic and quark matter equations of state. For the hadronic phase we employ the hypernuclear equation of state from the lowest order constrained variational method and the quark matter phase is described by a sufficiently stiff equation of state based on a color superconducting nonlocal Nambu-Jona-Lasinio model with constant (model nlNJLA) and with density-dependent (model nlNJLB) parameters. We study the model dependence of the phase transition obtained by a Maxwell construction. Our study confirms that also with the present set of equations of state quark deconfinement presents a viable solution of the hyperon puzzle even for the new constraint on the lower limit of the maximum mass from PSR J0740+6620. In this work we provide with model nlNJLB for the first time a hybrid star EoS with an intermediate hypernuclear matter phase between the nuclear and color superconducting quark matter phases, for which the maximum mass of the compact star reaches $2.2M_{\odot }$, in accordance with most recent constraints. In model nlNJLA such a phase cannot be realised because the phase transition onset is at low densities, before the hyperon threshold density is passed. We discuss possible consequences of the hybrid equation of state for the deconfinement phase transition in symmetric matter as it will be probed in future heavy-ion collisions at FAIR, NICA and corresponding energy scan programs at the CERN and RHIC facilities.

    ↳ nucl-thastro-ph.HEhep-phPRC(2020)·45 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.