Fri·Dec 2, 2016Friday·December 2, 2016

1. 01*

   Kinematics of Current Region Fragmentation in Semi-Inclusive Deeply Inelastic Scattering

   M. Boglione🇮🇹 · J. Collins🇺🇸 · L. Gamberg🇺🇸 · J. O. Gonzalez-Hernandez🇺🇸 · T. C. Rogers🇺🇸 · N. Sato🇺🇸

   Different kinematical regimes of semi-inclusive deeply inelastic scattering (SIDIS) processes correspond to different underlying partonic pictures, and it is important to understand the transition between them. This is particularly the case when there is sensitivity to intrinsic transverse momentum, in which case kinematical details can become especially important. We address the question of how to identify the current fragmentation region --- the kinematical regime where a factorization picture with fragmentation functions is appropriate. We distinguish this from soft and target fragmentation regimes. Our criteria are based on the kinematic regions used in derivations of factorization theorems. We argue that, when hard scales are of order a few GeVs, there is likely significant overlap between different rapidity regions that are normally understood to be distinct. We thus comment on the need to take this into account with more unified descriptions of SIDIS, which should span all rapidities for the produced hadron. Finally, we propose general criteria for estimating the proximity to the current region at large Q.

   hep-phnucl-thPLB(2017)·57 citations
2. 02*

   Package-X 2.0: A Mathematica package for the analytic calculation of one-loop integrals

   Hiren H. Patel🇩🇪

   This article summarizes new features and enhancements of the first major update of Package-X. Package-X 2.0 can now generate analytic expressions for arbitrarily high rank dimensionally regulated tensor integrals with up to four distinct propagators, each with arbitrary integer weight, near an arbitrary even number of spacetime dimensions, giving UV divergent, IR divergent, and finite parts at (almost) any real-valued kinematic point. Additionally, it can generate multivariable Taylor series expansions of these integrals around any non-singular kinematic point to arbitrary order. All special functions and abbreviations output by Package-X 2.0 supports Mathematica's arbitrary precision evaluation capabilities to deal with issues of numerical stability. Finally, tensor algebraic routines of Package-X have been polished and extended to support open fermion chains both on and off shell. The documentation (equivalent to over 100 printed pages) is accessed through Mathematica's Wolfram Documentation Center and contains information on all Package-X symbols, with over 300 basic usage examples, 3 project-scale tutorials, and instructions on linking to FeynCalc and LoopTools.

   hep-phComput.Phys.Commun.(2017)·368 citations
3. 03*

   Beauty-full Tetraquarks

   Yang Bai🇺🇸 · Sida Lu🇺🇸 · James Osborne🇺🇸

   In this article we present a calculation of the $bb\bar{b}\bar{b}$ tetraquark ground-state energy using a diffusion Monte Carlo method to solve the non-relativistic many-body system. The static potential for the four quark system is chosen to align with the flux-tube picture of QCD. Using this approach, we find that the $0^{++}$ state has a mass of $18.69\pm 0.03\text{mbox}GeV$, which is around 100 MeV below twice the ${\eta }_b$ mass. This bound state can behave as a four-lepton resonance via its decay to ${\rm Y}(1S){\rm Y}(1S{)}^{\ast }\to {\ell }^{+}{\ell }^{-}{\ell }^{+}{\ell }^{-}$.

   hep-phhep-exPLB(2019)·140 citations
4. 04*

   Three loop form factors of a massive spin-2 particle with nonuniversal coupling

   Taushif Ahmed🇮🇳 · Pulak Banerjee🇮🇳 · Prasanna K. Dhani🇮🇳 · Prakash Mathews🇮🇳 · Narayan Rana🇮🇳 · V. Ravindran🇮🇳

   We investigate the interaction of spin-2 fields with those of Standard Model in a model independent framework. We have considered interactions where the spin-2 fields couple to two sets of gauge invariant tensorial operators that are not conserved unlike the energy momentum tensor with different coupling strengths. Such interactions not only change the ultraviolet behaviour of the couplings but also expand the scope of the searches of spin-2 particles at the colliders. We present all the relevant renormalisation constants up to three loop level in QCD and also the form factors that contribute to potential observables. This sets the ground to investigate the phenomenological consequences of these interactions with spin-2 fields through more than one tensorial operator.

   hep-phhep-thPRD(2017)·15 citations
5. 05*

   Don't be left in the dark: Improving LHC searches for dark photons using lepton-jet substructure

   G. Barello🇺🇸 · Spencer Chang🇺🇸 · Christopher A. Newby🇺🇸 · Bryan Ostdiek🇺🇸

   Collider signals of dark photons are an exciting probe for new gauge forces and are characterized by events with boosted lepton jets. Existing techniques are efficient in searching for muonic lepton jets but due to substantial backgrounds have difficulty constraining lepton jets containing only electrons. This is unfortunate since upcoming intensity frontier experiments are sensitive to dark photon masses which only allow electron decays. Analyzing a recently proposed model of kinetic mixing, with new scalar particles decaying into dark photons, we find that existing techniques for electron jets can be substantially improved. We show that using lepton-jet-substructure variables, in association with a boosted decision tree, improves background rejection, significantly increasing the LHC's reach for dark photons in this region of parameter space.

   hep-phhep-exPRD(2017)·8 citations
6. 06*

   Irreducible tensor basis and general Fierz relations for Bhabha scattering like amplitudes

   Tao Liu🇨🇦 · Nikolai Zerf🇩🇪

   We construct an irreducible s- and t-channel tensor basis for Bhabha scattering like amplitudes based on the properties of the underlying Lorentz symmetry in four space-time dimensions. In the given basis the calculation of amplitude contractions like the amplitude square reduces to the contraction of their corresponding coefficient tensors. Further the basis retains the full amplitude information and thus can be applied in off-shell cases. The general Fierz transformations which relate the s- and t-channel basis with each other are obtained. As an example for application we use the basis to calculate the tree-level Bhabha scattering amplitude.

   hep-ph0 citations
7. 07*

   Energy Conservation and the Chiral Magnetic Effect

   David B. Kaplan🇺🇸 · Sanjay Reddy🇺🇸 · Srimoyee Sen🇺🇸

   We analyze the chiral magnetic effect in a homogeneous neutral plasma from the point of view of energy conservation, and construct an effective potential for the growth of maximally helical perturbations of the electromagnetic field. We show that a negative curvature at the origin of the potential, indicating instability of the plasma, is induced by a chiral asymmetry in electron Fermi energy, as opposed to number density, while the potential grows at large field value. It follows that the ground state for a plasma has zero magnetic helicity; a nonzero electron mass will allow an excited state of a plasma with nonzero helicity to relax to that ground state quickly. We conclude that a chiral plasma instability triggered by weak interactions is not a viable mechanism for explaining magnetic fields in stars except possibly when dynamics drives the system far from equilibrium.

   hep-phastro-ph.HEnucl-thPRD(2017)·40 citations
8. 08*

   Constraints for proton structure fluctuations from exclusive scattering

   H. Mäntysaari🇺🇸 · B. Schenke🇺🇸

   We constrain the average density profile of the proton and the amount of event-by-event fluctuations by simultaneously calculating the coherent and incoherent exclusive diffractive vector meson production cross section in deep inelastic scattering. Working within the Color Glass Condensate picture, we find that the gluonic density of the proton must have large geometric fluctuations in order to describe the experimentally measured large incoherent cross section.

   hep-phnucl-thNucl.Part.Phys.Proc.(2017)·1 citation
9. 09*

   LHC Signals from Cascade Decays of Warped Vector Resonances

   Kaustubh S. Agashe🇺🇸 · Jack Collins🇺🇸 · Peizhi Du🇺🇸 · Sungwoo Hong🇺🇸 · Doojin Kim🇺🇸 · Rashmish K. Mishra🇺🇸

   Recently (arXiv:1608.00526), a new framework for warped higher-dimensional compactifications with "bulk" standard model (SM) was proposed: in addition to the UV (Planck scale) and IR (a couple of TeV) branes, there is an intermediate brane, taken to be around 10 TeV. The SM matter and Higgs fields propagate from the UV brane down to this intermediate brane only, while gauge and gravity fields propagate in the entire bulk. Such a configuration renders the lightest gauge Kaluza-Klein (KK) states within LHC reach, simultaneously satisfying flavor and CP constraints. In addition, the usual leading decay modes of the lightest KK gauge bosons into top and Higgs bosons are suppressed. This effect permits erstwhile subdominant channels to become significant. These include flavor-universal decays to SM fermions and Higgs bosons, and a novel channel - decay to a radion and a SM gauge boson, followed by radion decay to a pair of SM gauge bosons. In this work, we first delineate the parameter space where the above mentioned cascade decay of gauge KK particles dominates, and thereby can be the discovery mode at the LHC. We then perform a detailed analysis of the LHC signals from this model, finding that 300/fb suffices for evidence of KK-gluon in tri-jet, jet + di-photon and jet + di-boson channels. However, KK photon in photon + di-jet, and KK-W in leptonic W + di-jet require 3000/fb. The crucial feature of this decay chain is a "double" resonance, i.e. 3-particle and 2-particle invariant mass peaks, corresponding to the KK gauge boson and the radion respectively.

   hep-phhep-exJHEP(2017)·60 citations
10. 10*

    Analysis of the mass and width of the $Y(4274)$ as axialvector molecule-like state

    Zhi-Gang Wang🇨🇳

    In this article, we assign the $Y(4274)$ to be the color octet-octet type axialvector molecule-like state with $J^{PC}=1^{++}$ tentatively, and construct the color octet-octet type axialvector current to study its mass and width with the QCD sum rules in details. The predicted mass favors assigning the $Y(4274)$ to be the color octet-octet type molecule-like state, but the predicted width disfavors assigning the $Y(4274)$ to be the color octet-octet type molecule-like state strongly. The $Y(4274)$ may be the conventional charmonium state ${\chi }_{c1}(3P)$, and it is important to observe the decay $Y(4274)\to J/\psi \omega$ to diagnose the nature of the $Y(4274)$.

    hep-phEPJC(2017)·23 citations
11. 11*

    On magnetization of quark-gluon plasma at the LHC experiment energies

    V. Skalozub🇺🇦 · P. Minaiev🇺🇦

    Large scale chromomagnetic, B_3, B_8, and usual magnetic,H, fields have to be generated in QCD after the deconfinement phase transition (DPT) at temperatures T larger than deconfinement temperature T_d. The two former fields are created spontaneously due to asymptotic freedom of gluon intaractions. Whereas H is produced due to either the feature of quarks to possess both electric and color charges or a vacuum polarization in this case. At the polarization, the vacuum quark loops mix the external fields. As a result, B_3, B_8 become the sources generating H. The latter field appears at $T$ much lower than the electroweak phase transition temperature T_ew. This mechanism should exhibit itself at the LHC experiments on heavy ion collisions. It operates at the one-loop diagram level for an effective potential. The created fields are temperature dependent and occupying the macroscopic volume of quark-gluon plasma. The magnetization influences different processes and may serve as a signal for the DPT.

    hep-ph2 citations
12. 12*

    Mono-X Versus Direct Searches: Simplified Models for Dark Matter at the LHC

    Seng Pei Liew🇯🇵 · Michele Papucci🇺🇸 · Alessandro Vichi🇺🇸 · Kathryn M. Zurek🇺🇸

    We consider simplified models for dark matter (DM) at the LHC, focused on mono-Higgs, -Z, or -b produced in the final state. Our primary purpose is to study the LHC reach of a relatively complete set of simplified models for these final states, while comparing the reach of the mono-X DM search against direct searches for the mediating particle. We find that direct searches for the mediating particle, whether in di-jets, jets+MET, multi-b+MET, or di-boson+MET, are usually stronger. We draw attention to the cases that the mono-X search is strongest, which include regions of parameter space in inelastic DM, two Higgs doublet, and squark mediated production models with a compressed spectrum.

    hep-phhep-exJHEP(2017)·32 citations
13. 13*

    Electroweak corrections to top quark pair production in association with a hard photon at hadron colliders

    Peng-Fei Duan🇨🇳 · Yu Zhang🇨🇳 · Yong Wang🇨🇳 · Mao Song🇨🇳 · Gang Li🇨🇳

    We present the next-to-leading order (NLO) electroweak (EW) corrections to the top quark pair production associated with a hard photon at the current and future hadron colliders. The dependence of the leading order (LO) and NLO EW corrected cross sections on the photon transverse momentum cut are investigated. We also provide the LO and NLO EW corrected distributions of the transverse momentum of final top quark and photon and the invariant mass of top quark pair and top-antitop-photon system. The results show that the NLO EW corrections are significant in high energy regions due to the EW Sudakov effect.

    hep-phPLB(2017)·33 citations
14. 14*

    Non-linear quantum dynamics in strong and short electromagnetic fields

    Alexander I. Titov🇷🇺 · Burkhard Kampfer🇩🇪 · Atsushi Hosaka🇯🇵 · Hideaki Takabe🇩🇪

    In our contribution we give a brief overview of two widely discussed quantum processes: electron-positron pairs production off a probe photon propagating through a polarized short-pulsed electromagnetic (e.m.) (e.g.\ laser) wave field or generalized Breit-Wheeler process and a single a photon emission off an electron interacting with the laser pules, so-called non-linear Compton scattering. We show that at small and moderate laser field intensities the shape and duration of the pulse are very important for the probability of considered processes. However, at high intensities the multi-photon interactions of the fermions with laser field are decisive and completely determined all aspects of subthreshold electron-positron pairs and photon production

    hep-ph0 citations
15. 15*

    Higgs boson couplings: measurements and theoretical interpretation

    Chiara Mariotti (INFN, Turin)🇮🇹 · Giampiero Passarino (Turin U. & INFN, Turin)🇮🇹

    This report will review the Higgs boson properties: the mass, the total width and the couplings to fermions and bosons. The measurements have been performed with the data collected in 2011 and 2012 at the LHC accelerator at CERN by the ATLAS and CMS experiments. Theoretical frameworks to search for new physics are also introduced and discussed.

    hep-phhep-exInt.J.Mod.Phys.A(2017)·21 citations
16. 16*

    Modeling BSM effects on the Higgs transverse-momentum spectrum in an EFT approach

    Massimiliano Grazzini🇨🇭 · Agnieszka Ilnicka🇨🇭 · Michael Spira🇨🇭 · Marius Wiesemann🇨🇭

    We consider the transverse-momentum distribution of a Higgs boson produced through gluon fusion in hadron collisions. At small transverse momenta, the large logarithmic terms are resummed up to next-to-leading-logarithmic (NLL) accuracy. The resummed computation is consistently matched to the next-to-leading-order (NLO) result valid at large transverse momenta. The ensuing Standard Model prediction is supplemented by possible new-physics effects parametrised through three dimension-six operators related to the modification of the top and bottom Yukawa couplings, and to the inclusion of a point-like Higgs-gluon coupling, respectively. We present resummed transverse-momentum spectra including the effect of these operators at NLL+NLO accuracy and study their impact on the shape of the distribution. We find that such modifications, while affecting the total rate within the current uncertainties, can lead to significant distortions of the spectrum. The proper parametrization of such effects becomes increasingly important for experimental analyses in Run II of the LHC.

    hep-phJHEP(2017)·104 citations
17. 17*

    $ND$ and $NB$ systems in quark delocalization color screening model

    Lifang Zhao🇨🇳 · Hongxia Huang🇨🇳 · Jialun Ping🇨🇳

    The $ND$ and $NB$ systems with $I=0$ and $1$, $J^P={\frac{1}{2}}^{\pm }$, ${\frac{3}{2}}^{\pm }$, and ${\frac{5}{2}}^{\pm }$ are investigated within the framework of quark delocalization color screening model. The results show that all the positive parity states are unbound. By coupling to the $N{D}^{\ast }$ channel, the state $ND$ with $I=0,J^P={\frac{1}{2}}^{-}$ can form a bound state, which can be invoked to explain the observed $\Sigma (2800)$ state. The mass of the $N{D}^{\ast }$ with $I=0,J^P={\frac{3}{2}}^{-}$ is close to that of the reported ${\Lambda }_c(2940{)}^{+}$, which indicates that ${\Lambda }_c(2940{)}^{+}$ can be explained as a $N{D}^{\ast }$ molecular state in QDCSM. Besides, the $\Delta D^{\ast }$ with $I=1,J^P={\frac{5}{2}}^{-}$ is also a possible resonance state. The results of the bottom case of $NB$ system are similar to those of the $ND$ system. Searching for these states will be a challenging subject of experiments.

    hep-phnucl-thEPJA(2017)·20 citations
18. 18*

    Modelling Wt and tWZ production at NLO for ATLAS analyses

    Olga Bessidskaia Bylund🇸🇪

    The generation of single top production in the $Wt$ channel at NLO gives rise to doubly-resonant diagrams that overlap with $t\bar{t}$, and similarly for associated production with a $Z$ or Higgs boson. Several methods exist to remove this overlap, thus avoiding double counting and separating the two processes. In Diagram Removal 1, the amplitudes of doubly-resonant diagrams are set to zero, which also removes the interference of $Wt$ with $t\bar{t}$. If a measurement is performed in a region where this interference is not negligible, it would be of interest to take it into account. Another method, Diagram Subtraction, preserves the interference. However, it relies upon momentum reshuffling, which introduces uncertainties to the prediction. An alternative method, Diagram Removal 2, does not involve reshuffling and preserves the interference by subtracting the amplitude squared of the doubly-resonant diagrams from the total. The predictions of Diagram Removal 2 from MG5_aMC@NLO are compared with other predictions for $Wt$ and $tWZ$ production in the context of analyses at the ATLAS experiment. Implications of using Diagram Removal 2 are discussed, both for measurements of single top processes and when $Wt$ or $tWZ$ are treated as a background. Differential distributions are shown, investigating in what regions the predictions differ the most.

    hep-phhep-ex18 citations
19. 19*

    Production of quarkonia and doubly heavy baryons in $pp$-collisions with duality approach

    V.V. Kiselev🇷🇺 · A.A. Novoselov🇷🇺 · E.R. Tagiev🇷🇺

    In present work we discuss the production of heavy quarkonia and diquarks in $pp$-interactions. The aim is to take into account the production of bound states of quarks originating from independent parton scatterings. This production is regulated by constraints on the invariant mass of constituents. Such an approach leads to larger value of the diquark production cross section than traditional consideration in single parton scattering. This production mechanism of doubly heavy baryons can sooner be verified by modern experiments (e.g. LHCb). We also discuss related contributions to double and associated quarkonium production.

    hep-ph2 citations
20. 20*

    Testing local Lorentz invariance with short-range gravity

    Alan Kostelecky🇺🇸 · Matthew Mewes🇺🇸

    The Newton limit of gravity is studied in the presence of Lorentz-violating gravitational operators of arbitrary mass dimension. The linearized modified Einstein equations are obtained and the perturbative solutions are constructed and characterized. We develop a formalism for data analysis in laboratory experiments testing gravity at short range and demonstrate that these tests provide unique sensitivity to deviations from local Lorentz invariance.

    ↳ gr-qchep-phPLB(2017)·56 citations
21. 21*

    Low Energy Supergravity Revisited (I)

    Gilbert Moultaka🇫🇷 · Michel Rausch de Traubenberg🇫🇷 · Damien Tant🇫🇷

    General forms of the Kähler and superpotenials that lead to consistent low energy broken Supersymmetry originating from $N=1$ Supergravity have been classified and used for model building since more than three decades. We point out the incompleteness of this classification when hidden sector vacuum expectation values are of the order of the Planck mass. Focusing in this paper mainly on the case of minimal Kähler potential, we adopt a rigorous approach that retrieves on the one hand the known forms, and demonstrate on the other hand the existence of a whole set of new forms for the superpotential of which we give a complete classification. The latter forms involve a new type of chiral superfields having the unusual property of belonging neither to the hidden sector nor to the conventional observable sector. Comparing the obtained forms with the conventional ones, we argue how new possibilities for model building can arise, and discuss the gravity mediation of soft as well as additional hard (but parametrically small) Supersymmetry breaking, in the presence of the new type of chiral superfields. In the simplest case, we study the vacuum structure, characterize the masses and couplings of the scalar components to the hidden and observable sectors and discuss briefly the physical role they could play. In the generic case, we estimate the magnitude and possible consequences of the hard breaking of Supersymmetry in terms of the interplay between hidden and visible sectors mass scales.

    ↳ hep-thhep-phInt.J.Mod.Phys.A(2019)·9 citations
22. 22*

    Gravitational waves and large field inflation

    Andrei Linde🇺🇸

    According to the famous Lyth bound, one can confirm large field inflation by finding tensor modes with sufficiently large tensor-to-scalar ratio $r$. Here we will try to answer two related questions: Is it possible to rule out all large field inflationary models by not finding tensor modes with $r$ above some critical value, and what can we say about the scale of inflation by measuring $r$? However, in order to answer these questions one should distinguish between two different definitions of the large field inflation and three different definitions of the scale of inflation. We will examine these issues using the theory of cosmological $\alpha$-attractors as a convenient testing ground.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2017)·27 citations
23. 23*

    Exploring Cosmic Origins with CORE: Cosmological Parameters

    Eleonora Di Valentino · Thejs Brinckmann · Martina Gerbino · Vivian Poulin · François R. Bouchet · Julien Lesgourgues · Alessandro Melchiorri · Jens Chluba · Sebastien Clesse · Jacques Delabrouille · Cora Dvorkin · Francesco Forastieri and 116 other authors

    We forecast the main cosmological parameter constraints achievable with the CORE space mission which is dedicated to mapping the polarisation of the Cosmic Microwave Background (CMB). CORE was recently submitted in response to ESA's fifth call for medium-sized mission proposals (M5). Here we report the results from our pre-submission study of the impact of various instrumental options, in particular the telescope size and sensitivity level, and review the great, transformative potential of the mission as proposed. Specifically, we assess the impact on a broad range of fundamental parameters of our Universe as a function of the expected CMB characteristics, with other papers in the series focusing on controlling astrophysical and instrumental residual systematics. In this paper, we assume that only a few central CORE frequency channels are usable for our purpose, all others being devoted to the cleaning of astrophysical contaminants. On the theoretical side, we assume LCDM as our general framework and quantify the improvement provided by CORE over the current constraints from the Planck 2015 release. We also study the joint sensitivity of CORE and of future Baryon Acoustic Oscillation and Large Scale Structure experiments like DESI and Euclid. Specific constraints on the physics of inflation are presented in another paper of the series. In addition to the six parameters of the base LCDM, which describe the matter content of a spatially flat universe with adiabatic and scalar primordial fluctuations from inflation, we derive the precision achievable on parameters like those describing curvature, neutrino physics, extra light relics, primordial helium abundance, dark matter annihilation, recombination physics, variation of fundamental constants, dark energy, modified gravity, reionization and cosmic birefringence. (ABRIDGED)

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2018)·204 citations
24. 24*

    Constraining Black Holes with Light Boson Hair and Boson Stars using Epicyclic Frequencies and QPOs

    Nicola Franchini🇮🇹 · Paolo Pani🇮🇹 · Andrea Maselli🇩🇪 · Leonardo Gualtieri🇮🇹 · Carlos A R Herdeiro🇵🇹 · Eugen Radu🇵🇹 · Valeria Ferrari🇮🇹

    Light bosonic fields are ubiquitous in extensions of the Standard Model. Even when minimally coupled to gravity, these fields might evade the assumptions of the black-hole no-hair theorems and give rise to spinning black holes which can be drastically different from the Kerr metric. Furthermore, they allow for self-gravitating compact solitons, known as (scalar or Proca) boson stars. The quasi-periodic oscillations (QPOs) observed in the X-ray flux emitted by accreting compact objects carry information about the strong-field region, thus providing a powerful tool to constrain deviations from Kerr's geometry and to search for exotic compact objects. By using the relativistic precession model as a proxy to interpret the QPOs in terms of geodesic frequencies, we investigate how the QPO frequencies could be used to test the no-hair theorem and the existence of light bosonic fields near accreting compact objects. We show that a detection of two QPO triplets with current sensitivity can already constrain these models, and that the future eXTP mission or a LOFT-like mission can set very stringent constraints on black holes with bosonic hair and on (scalar or Proca) boson stars. The peculiar geodesic structure of compact scalar/Proca boson stars implies that these objects can easily be ruled out as alternative models for X-ray source GRO J1655-40.

    ↳ astro-ph.HEgr-qchep-phPRD(2017)·34 citations
25. 25*

    Semiholography for heavy ion collisions

    Ayan Mukhopadhyay🇦🇹 · Florian Preis🇦🇹

    The formation of QGP in heavy ion collisions gives us a great opportunity for learning about nonperturbative dynamics of QCD. Semiholography provides a new consistent framework to combine perturbative and non-perturbative effects in a coherent way and can be applied to obtain an effective description for heavy ion collisions. In particular, it allows us to include nonperturbative effects in existing glasma effective theory and QCD kinetic theory for the weakly coupled saturated degrees of freedom liberated by the collisions in the initial stages in a consistent manner. We argue why the full framework should be able to confront experiments with only a few phenomenological parameters and present feasibility tests for the necessary numerical computations. Furthermore, we discuss that semiholography leads to a new description of collective flow in the form of a generalised non-Newtonian fluid. We discuss some open questions which we hope to answer in the near future.

    ↳ hep-thhep-phEPJ Web Conf.(2017)·2 citations
26. 26*

    Electromagnetic corrections to leptonic decay rates of charged pseudoscalar mesons: finite-volume effects

    N. Tantalo🇮🇹 · V. Lubicz🇮🇹 · G. Martinelli🇮🇹 · C.T. Sachrajda🇬🇧 · F. Sanfilippo🇬🇧 · S. Simula🇮🇹

    In Carrasco et al. we have recently proposed a method to calculate $O(e^2)$ electromagnetic corrections to leptonic decay widths of pseudoscalar mesons. The method is based on the observation that the infrared divergent contributions (that appear at intermediate stages of the calculation and that cancel in physical quantities thanks to the Bloch-Nordsieck mechanism) are universal, i.e. depend on the charge and the mass of the meson but not on its internal structure. In this talk we perform a detailed analysis of the finite-volume effects associated with our method. In particular we show that also the leading $1/L$ finite-volume effects are universal and perform an analytical calculation of the finite-volume leptonic decay rate for a point-like meson.

    ↳ hep-lathep-ph30 citations
27. 27*

    Equation of state of the SU($3$) Yang-Mills theory: a precise determination from a moving frame

    Leonardo Giusti (Milan Bicocca U. & INFN, Milan Bicocca)🇮🇹 · Michele Pepe (INFN, Milan Bicocca)🇮🇹

    The equation of state of the SU($3$) Yang-Mills theory is determined in the deconfined phase with a precision of about 0.5%. The calculation is carried out by numerical simulations of lattice gauge theory with shifted boundary conditions in the time direction. At each given temperature, up to $230T_c$ with $T_c$ being the critical temperature, the entropy density is computed at several lattice spacings so to be able to extrapolate the results to the continuum limit with confidence. Taken at face value, above a few $T_c$ the results exhibit a striking linear behaviour in $\ln (T/T_c{)}^{-1}$ over almost 2 orders of magnitude. Within errors, data point straight to the Stefan-Boltzmann value but with a slope grossly different from the leading-order perturbative prediction. The pressure is determined by integrating the entropy in the temperature, while the energy density is extracted from $Ts=(ϵ+p)$. The continuum values of the potentials are well represented by Padé interpolating formulas, which also connect them well to the Stefan-Boltzmann values in the infinite temperature limit. The pressure, the energy and the entropy densities are compared with results in the literature. The discrepancy among previous computations near $T_c$ is analyzed and resolved thanks to the high precision achieved.

    ↳ hep-latastro-ph.HEhep-phhep-thPLB(2017)·86 citations
28. 28*

    Stringy bounces and gradient instabilities

    Massimo Giovannini🇨🇭

    Bouncing solutions are obtained from a generally covariant action characterized by a potential which is a nonlocal functional of the dilaton field at two separated space-time points. Gradient instabilities are shown to arise in this context but they are argued to be nongeneric. After performing a gauge-invariant and frame-invariant derivation of the evolution equations of the fluctuations, a heuristic criterion for the avoidance of pathological instabilities is proposed and corroborated by a number of explicit examples that turn out to be compatible with a quasi-flat spectrum of curvature inhomogeneities for typical wavelengths larger than the Hubble radius.

    ↳ hep-thastro-ph.COgr-qchep-phPRD(2017)·11 citations
29. 29*

    Fantasia of a Superfluid Universe -- In memory of Kerson Huang

    Hwee-Boon Low🇸🇬 · Chi Xiong🇸🇬

    This article introduces Kerson Huang's theory on superfluid universe in these aspects: I. choose the asymptotically free Halpern-Huang scalar field(s) to drive inflation; II. use quantum turbulence to create matter; III. consider dark energy as the energy density of the cosmic superfluid and dark matter the deviation of the superfluid density from its equilibrium value; IV. use quantum vorticity to explain phenomena such as the non-thermal filaments at the galactic center, the large voids in the galactic distribution, and the gravitational collapse of stars to fast-rotating blackholes.

    ↳ astro-ph.COgr-qchep-phMemorial Volume for Kerson Huang, Edited …·1 citation

* 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.