Thu·May 21, 2020Thursday·May 21, 2020

1. 01*

   Medium modification of $\gamma$-jet fragmentation functions in Pb+Pb collisions at LHC

   Wei Chen🇨🇳 · Shanshan Cao🇺🇸 · Tan Luo🇪🇸 · Long-Gang Pang🇨🇳 · Xin-Nian Wang🇨🇳

   Coupled linear Boltzmann transport and hydrodynamic (CoLBT-hydro) model has been developed for simultaneous simulations of jet propagation and jet-induced medium excitation in heavy-ion collisions. Within this coupled approach, the final reconstructed jets in heavy-ion collisions include not only hadrons from the hadronization of medium modified jet shower partons from the linear Boltzmann transport (LBT) but also hadrons from the freeze-out of the jet-induced medium excitation in the hydrodynamic evolution of the bulk medium. Using the CoLBT-hydro model, we study medium modification of the fragmentation functions of $\gamma$-triggered jets in high-energy heavy-ion collisions at the Large Hadron Collider. The CoLBT-hydro model is shown to describe the experimental data not only on the suppression of leading hadrons within the jet cone at large momentum fraction $z_{\gamma }=p_T^h/p_T^{\gamma }$ relative to the transverse momentum of the trigger photon due to parton energy loss but also the enhancement of soft hadrons at small $z_{\gamma }$ and $z_{\mathrm{jet}}=p_T^h/p_T^{\mathrm{jet}}$ due to jet-induced medium excitation. There is no suppression of the fragmentation function, however, at large momentum fraction $z_{\mathrm{jet}}$ relative to the transverse momentum of the reconstructed jet due to trigger bias and medium modification of quark to gluon jet fraction. For jets whose final transverse momenta are comparable to or larger than that of the trigger photon, the trigger bias can lead to enhancement of the jet fragmentation function at large $z_{\mathrm{jet}}$.

   hep-phnucl-thPLB(2020)·79 citations
2. 02*

   Parton Distribution Functions and Tensor Gluons

   Roland Kirschner🇩🇪 · George Savvidy🇬🇷

   We further consider a possibility that inside the proton and, more generally, inside the hadrons, there are additional partons - tensor gluons, which can carry a part of the proton momentum. The tensorgluons have zero electric charge, like gluons, but have a larger spin. Inside the proton a nonzero density of the tensorgluons can be generated by the emission of tensorgluons by gluons. The last mechanism is typical for non-Abelian tensor gauge theories. The process of gluon splitting suggests that part of the proton momentum that was carried by neutral partons is shared between vector and tensor gluons. We derive the regularised evolution equations for the parton distribution functions that take into account these new processes. In particular, this will allow to solve numerically the extended DIGLAP equations and to find out the ratio of densities between gluons and tensorgluons.

   hep-phhep-th0 citations
3. 03*

   T-odd generalized and quasi transverse momentum dependent parton distribution in a scalar spectator model

   Xuan Luo🇨🇳 · Hao Sun🇨🇳

   Generalized transverse momentum dependent parton distributions (GTMDs), as mother funtions of transverse momentum dependent parton distributions (TMDs) and generalized parton distributions (GPDs), encode the most general parton structure of hadrons. We calculate four twist-two time reversal odd GTMDs of pion in a scalar spectator model. We study the dependence of GTMDs on the longitudinal momentum fraction $x$ carried by the active quark and the transverse momentum $|{\vec{k}}_T|$ for different values of skewness $\xi$ defined as the longitudinal momentum transferred to the proton as well as the total momentum $|{\vec{\Delta }}_T|$ transferred to the proton. In addition, the quasi-TMDs and quasi-GPDs of pion have also been investigated in this paper.

   hep-phnucl-thEPJC(2020)·18 citations
4. 04*

   Beyond the Standard Model in Vector Boson Scattering Signatures

   Michele Gallinaro🇵🇹 · Kenneth Long🇬🇧 · Jürgen Reuter🇩🇪 · Richard Ruiz🇧🇪 · Dinos Bachas🇬🇷 · Liron Barak🇮🇱 · Fady Bishara🇩🇪 · Ilaria Brivio🇩🇪 · Diogo Buarque Franzosi🇸🇪 · Giacomo Cacciapaglia🇫🇷 · Farida Fassi🇲🇦 · Eirini Kasimi🇬🇷 and 10 other authors

   The high-energy scattering of massive electroweak bosons, known as vector boson scattering (VBS), is a sensitive probe of new physics. VBS signatures will be thoroughly and systematically investigated at the LHC with the large data samples available and those that will be collected in the near future. Searches for deviations from Standard Model (SM) expectations in VBS facilitate tests of the Electroweak Symmetry Breaking (EWSB) mechanism. Current state-of-the-art tools and theory developments, together with the latest experimental results, and the studies foreseen for the near future are summarized. A review of the existing Beyond the SM (BSM) models that could be tested with such studies as well as data analysis strategies to understand the interplay between models and the effective field theory paradigm for interpreting experimental results are discussed. This document is a summary of the EU COST network "VBScan" workshop on the sensitivity of VBS processes for BSM frameworks that took place December 4-5, 2019 at the LIP facilities in Lisbon, Portugal. In this manuscript we outline the scope of the workshop, summarize the different contributions from theory and experiment, and discuss the relevant findings.

   hep-phhep-ex17 citations
5. 05*

   Probing Electroweak Baryogenesis induced by extra bottom Yukawa coupling via EDMs and collider signatures

   Tanmoy Modak🇹🇼 · Eibun Senaha🇻🇳

   We study the prospect of probing electroweak baryogenesis driven by an extra bottom Yukawa coupling ${\rho }_{bb}$ in a general two Higgs doublet model via electric dipole moment (EDM) measurements and at the collider experiments. The parameter space receives meaningful constraints from 125 GeV Higgs $h$ boson signal strength measurements as well as several heavy Higgs boson searches at the Large Hadron Collider (LHC). In addition, we show that the asymmetry of the CP asymmetry of inclusive $B\to X_s\gamma$ decay would provide complementary probe. A discovery is possible at the LHC via $bg\to bA\to bZh$ process if $|{\rho }_{bb}|\sim 0.15$ and $250\text{mbox}GeV\lesssim m_A\lesssim 350$ GeV, where $A$ is CP odd scalar. For $m_A>2m_t$ threshold, where $m_t$ is the top quark mass, one may also discover $bg\to bA\to bt\bar{t}$ at the high luminosity LHC run if an extra top Yukawa coupling $|{\rho }_{tt}|\sim 0.5$, though it may suffer from systematic uncertainties. For completeness we study $gg\to t\bar{t}A\to t\bar{t}b\bar{b}$ but find it not promising.

   hep-phhep-exJHEP(2020)·16 citations
6. 06*

   On some properties of the fourth-rank hadronic vacuum polarization tensor and the anomalous magnetic moment of the muon

   Marc Knecht🇫🇷

   Some short-distance properties of the fourth-rank hadronic vacuum polarization tensor are re-examined.Their consequences are critically discussed in the context of the hadronic light-by-light scattering contribution to the anomalous magnetic moment of the muon.

   hep-phJHEP(2020)·51 citations
7. 07*

   Single production of vector-like bottom quark at the LHeC

   Xue Gong🇨🇳 · Chong-Xing Yue🇨🇳 · Hai-Mei Yu🇨🇳 · Dong Li🇨🇳

   Existences of vector-like quarks (VLQs) are predicted in many new physics scenarios beyond the Standard Model (SM). We study the possibility of detecting the vector-like bottom quark (VLQ-$B$) being the $SU(2)$ singlet with electric charge $-1/3$ at the Large Hadron Electron Collider (LHeC) in a model-independent framework. The decay properties and single production of VLQ-$B$ at the LHeC are explored. Three types of signatures are investigated. By carrying out a fast simulation for the signals and the corresponding backgrounds, the signal significances are obtained. Our numerical results show that detecting of VLQ-$B$ via the semileptonic channel is better than via the fully hadronic or leptonic channel.

   hep-phEPJC(2020)·16 citations
8. 08*

   The Dark Side of 4321

   Diego Guadagnoli🇫🇷 · Meril Reboud🇫🇷 · Peter Stangl🇫🇷

   The evidence of Dark Matter (DM) is one of the strongest observational arguments in favour of physics beyond the Standard Model. Despite expectations, a similar evidence has been lacking so far in collider searches, with the possible exception of $B$-physics discrepancies, a coherent set of persistent deviations in a homogeneous dataset consisting of $b\to c$ and $b\to s$ semi-leptonic transitions. We explore the question whether DM and the $B$ discrepancies may have a common origin. We do so in the context of the so-called 4321 gauge model, a UV-complete and calculable setup that yields a $U_1$ leptoquark, the by far most successful single mediator able to explain the $B$ anomalies, along with other new gauge bosons, including a $Z^{\prime }$. Adding to this setup a 'minimal' DM fermionic multiplet, consisting of a $4$ under the 4321's $SU(4)$, we find the resulting model in natural agreement with the relic-density observation and with the most severe direct-detection bounds, in the sense that the parameter space selected by $B$ physics is also the one favoured by DM phenomenology. The DM candidate is a particle with a mass in the WIMP range, freeze-out dynamics includes a co-annihilator (the 'rest' of the $4$ multiplet), and the most important gauge mediator in the DM sector is the $Z^{\prime }$.

   hep-phJHEP(2020)·39 citations
9. 09*

   Scaling of PDFs, TMDs, and GPDs in soft-wall AdS/QCD

   Valery E. Lyubovitskij🇩🇪 · Ivan Schmidt🇨🇱

   We explicitly demonstrate how to correctly define the hadronic parton distributions (PDFs, TMDs, and GPDs) in the soft-wall AdS/QCD approach, based on the use of a quadratic dilaton field, providing confinement and spontaneous breaking of conformal and chiral symmetries. The power behavior of parton distributions at large values of the light-cone variable is consistent with quark counting rules and Drell-Yan-West duality. All parton distributions are defined in terms of profile functions, which depend on the light-cone coordinate and are fixed from PDFs and electromagnetic form factors.

   hep-phPRD(2020)·18 citations
10. 10*

    Mixed QCD-electroweak corrections to on-shell Z production at the LHC

    Federico Buccioni🇬🇧 · Fabrizio Caola🇬🇧 · Maximilian Delto🇩🇪 · Matthieu Jaquier🇩🇪 · Kirill Melnikov🇩🇪 · Raoul Röntsch🇨🇭

    We present the first complete calculation of mixed QCD-electroweak corrections to the production of on-shell $Z$ bosons in hadron collisions and their decays to massless charged leptons. Our computation is fully differential with respect to final state QCD partons and resolved photons, allowing us to compute any infra-red safe observable pertinent to the $pp\to Z\to l^{+}{l}^{-}$ process in the approximation that the $Z$ boson is on shell. Although mixed QCD-electroweak corrections are small, at about the per mill level, we observe that the interplay between QCD-QED and QCD-weak contributions is subtle and observable-dependent. It is therefore not possible to avoid computing one or the other if $\mathcal{O}({\alpha }_{EW}{\alpha }_s)$ precision is desired.

    hep-phhep-exPLB(2020)·57 citations
11. 11*

    Detectability of Axion Dark Matter with Phonon Polaritons and Magnons

    Andrea Mitridate🇺🇸 · Tanner Trickle🇺🇸 · Zhengkang Zhang🇺🇸 · Kathryn M. Zurek🇺🇸

    Collective excitations in condensed matter systems, such as phonons and magnons, have recently been proposed as novel detection channels for light dark matter. We show that excitation of i) optical phonon polaritons in polar materials in an $\mathcal{O}$(1 T) magnetic field (via the axion-photon coupling), and ii) gapped magnons in magnetically ordered materials (via the axion wind coupling to the electron spin), can cover the difficult-to-reach $\mathcal{O}$(1-100) meV mass window of QCD axion dark matter with less than a kilogram-year exposure. Finding materials with a large number of optical phonon or magnon modes that can couple to the axion field is crucial, suggesting a program to search for a range of materials with different resonant energies and excitation selection rules; we outline the rules and discuss a few candidate targets, leaving a more exhaustive search for future work. Ongoing development of single photon, phonon and magnon detectors will provide the key for experimentally realizing the ideas presented here.

    hep-phastro-ph.COcond-mat.mtrl-sciPRD(2020)·83 citations
12. 12*

    How transverse thermal fluctuations disorder a condensate of chiral spirals into a quantum spin liquid

    Robert D. Pisarski🇺🇸 · Alexei M. Tsvelik🇺🇸 · Semeon Valgushev🇺🇸

    For a scalar theory with a global $O(N)$ symmetry, when $N=2$ a spatially inhomogeneous condensate arises when the term in the Lagrangian with two spatial derivatives has a negative coefficient. If the condensate for such a chiral spiral includes only one mode, characterized by a momentum $k_0\hat{z}$, then in perturbation theory at nonzero temperature the propagator for the static mode has a double pole when ${\vec{k}}^2=k_0^2$. We conjecture that since chiral spirals spontaneously break both global and spacetime symmetries, that such double poles are a universal property of their static transverse modes. Fluctuations from double poles generate linear infrared divergences in any number of spatial dimensions and disorder the condensate of chiral spirals, analogous to a type of quantum spin liquid. The characteristic feature of this region is that over large spatial distances the two point function is the usual exponential times an oscillatory function. We prove this at large $N$ and suggest this occurs for all $N>2$. Implications for four-fermion models and the phase diagram of QCD are discussed.

    hep-phcond-mat.stat-mechnucl-thPRD(2020)·53 citations
13. 13*

    Renormalization Group Evolution from On-shell SMEFT

    Minyuan Jiang🇨🇳 · Teng Ma🇮🇱 · Jing Shu🇨🇳

    We describe the on-shell method to deriving the Renormalization Group (RG) evolution of Wilson coefficients of high dimensional operators at one loop, which is a necessary part in the on-shell construction of the Standard Model Effective Field Theory (SMEFT), and exceptionally efficient based on the amplitude basis in hand. The UV divergence is obtained by firstly calculating the coefficients of scalar bubble integrals by unitary cuts, then subtracting the IR divergence in the massless bubbles, which can be easily read from the collinear factors we obtained for the Standard Model fields. Examples of deriving the anomalous dimensions at dimension six are presented in a pedagogical manner. We also give the results of contributions from the dimension-8 $H^4{D}^4$ operators to the running of $V^{+}{V}^{-}{H}^2$ operators, as well as the running of $B^{+}{B}^{-}{H}^2{D}^{2n}$ from $H^4{D}^{2n+4}$ for general $n$.

    hep-phhep-thJHEP(2021)·58 citations
14. 14*

    Probing Source and Detector NSI parameters at the DUNE Near Detector

    Alessio Giarnetti🇮🇹 · Davide Meloni🇮🇹

    We investigate the capability of the DUNE Near Detector (ND) to constrain Non Standard Interaction parameters (NSI) describing the production of neutrinos (${\epsilon }_{\alpha \beta }^s$) and their detection (${\epsilon }_{\alpha \beta }^d$). We show that the DUNE ND is able to reject a large portion of the parameter space allowed by DUNE Far Detector analyses and to set the most stringent bounds from accelerator neutrino experiments on $|{\epsilon }_{\mu e}^{s,d}|$ for wide intervals of the related phases. We also provide simple analytic understanding of our results as well as a numerical study of their dependence on the systematic errors, showing that the DUNE ND offers a clean environment where to study source and detector NSI.

    hep-phPRD(2021)·15 citations
15. 15*

    Remarks on the analysis of the reaction $e^{+}{e}^{-}\to {\Sigma }^0{\bar{\Sigma }}^0$

    Göran Fäldt🇸🇪

    We investigate roads for evaluating model-independent cross-section distributions for the sequential hyperon decay ${\Sigma }^0\to \Lambda \gamma ;\Lambda \to p{\pi }^{-}$ and its corresponding antihyperon decay. The hyperons are produced in the reaction $e^{+}{e}^{-}\to J/\psi \to {\Sigma }^0{\bar{\Sigma }}^0$. Cross-section distributions are calculated using the folding technique.

    hep-phPRD(2021)·1 citation
16. 16*

    Dark energy, Ricci-nonflat spaces, and the Swampland

    Luis A. Anchordoqui🇺🇸 · Ignatios Antoniadis🇫🇷 · Dieter Lust🇩🇪 · Jorge F. Soriano🇺🇸

    It was recently pointed out that the existence of dark energy imposes highly restrictive constraints on effective field theories that satisfy the Swampland conjectures. We provide a critical confrontation of these constraints with the cosmological framework emerging from the Salam-Sezgin model and its string realization by Cvetic, Gibbons, and Pope. We also discuss the implication of the constraints for string model building.

    ↳ hep-thastro-ph.COhep-phPLB(2021)·18 citations
17. 17*

    Dark Energy in String Theory

    Bruno Valeixo Bento🇬🇧 · Dibya Chakraborty🇲🇽 · Susha L. Parameswaran🇬🇧 · Ivonne Zavala🇬🇧

    We consider various candidates for Dark Energy, motivated by string theory. Several no-go theorems push de Sitter string vacua, with $w=-1$, to the limits of theoretical control, and all known examples depend on a delicate interplay between different string theoretic ingredients. On the other hand, runaway moduli directions are ubiquitous in string theory, and could plausibly source slow-roll quintessence. We consider various candidate supergravity potentials, motivated by string theory, including single-field Kähler potentials for bulk and local moduli, and leading superpotentials of the form $W=W_0+A{e}^{-a\Phi }$ or $W=W_0+A{\Phi }^p$. Conditions on the scalar potential imposed by supergravity are very restrictive, ruling out e.g. quintessence with $K=-n\ln (\Phi +\bar{\Phi })$ and $W=W_0+A{\Phi }^p$. Out of the examples considered, one can simultaneously satisfy $V>0$ and ${ϵ}_V<1$ only for a deformation-like modulus with $K=k_0+\frac{|\Phi {|}^{2n}}{k1}$ and a blow-up like modulus with $K=k_0+\frac{(\Phi +\bar{\Phi }{)}^{2n}}{k_1}$ when the leading order in the perturbative superpotential, $p$, is equal to $n$. We also review the scenario of Thermal Dark Energy, where thermal effects in a light hidden sector hold a scalar field up away from the minimum of its zero-temperature potential. This provides a viable model of Dark Energy with $w=-1$, consistent with known swampland conjectures, and motivates further early Thermal Dark Energy epochs with potentially observable consequences.

    ↳ hep-thastro-ph.COgr-qchep-phPoS(2020)·33 citations
18. 18*

    Chirally improved quark Pauli blocking in nuclear matter and applications to quark deconfinement in neutron stars

    David Blaschke🇵🇱 · Hovik Grigorian🇷🇺 · Gerd Röpke🇩🇪

    The relativistic mean field (RMF) model of the nuclear matter equation of state has been modified by including the effect of Pauli-blocking owing to quark exchange between the baryons. Different schemes of a chiral enhancement of the quark Pauli blocking have been suggested according to the adopted density dependence of the dynamical quark mass. The resulting equations of state for the pressure are compared to the RMF model DD2 with excluded volume correction. On the basis of this comparison a density-dependent nucleon volume is extracted which parametrises the quark Pauli blocking effect in the respective scheme of chiral enhancement. The dependence on the isospin asymmetry is investigated and the corresponding density dependent nuclear symmetry energy is obtained in fair accordance with phenomenological constraints. The deconfinement phase transition is obtained by a Maxwell construction with a quark matter phase described within a higher order NJL model. Solutions for rotating and nonrotating (hybrid) compact star sequences are obtained which show the effect of high-mass twin compact star solutions for the rotating case.

    ↳ nucl-thastro-ph.HEhep-phParticles(2020)·33 citations
19. 19*

    Revisiting relativistic magnetohydrodynamics from quantum electrodynamics

    Masaru Hongo🇺🇸 · Koichi Hattori🇯🇵

    We provide a statistical mechanical derivation of relativistic magnetohydrodynamics on the basis of the $(3+1)$-dimensional quantum electrodynamics; the system endowed with the magnetic one-form symmetry. The conservation laws and the constitutive relations are presented in a manifestly covariant way with respect to the general coordinate transformation. The method of the local Gibbs ensemble (or nonequilibrium statistical operator) combined with the path-integral formula for the thermodynamic functional enables us to obtain an exact form of the constitutive relations. Applying the derivative expansion to the exact formula, we derive the first-order constitutive relations for the relativistic magnetohydrodynamics. The result for the QED plasma preserving the parity and charge-conjugation symmetries is equipped with two electrical resistivities and five (three bulk and two shear) viscosities. We also show that those transport coefficients satisfy the Onsager's reciprocal relation and a set of inequalities, indicating the semi-positivity of the entropy production rate consistent with the local second law of thermodynamics.

    ↳ hep-thastro-ph.HEcond-mat.stat-mechhep-ph+1JHEP(2021)·16 citations
20. 20*

    Advanced Concepts in Quantum Field Theory

    James M. Cline🇨🇦

    These lectures comprise the second half of a quantum field theory course given in 2004. Topics include the path integral, loop expansion, Feynman rules, various regularization methods, renormalization, running couplings and the renormalization group, fixed points and asymptotic freedom, effective action, Coleman-Weinberg effective potential, fermions, the axial anomaly, QED, gauge fixing, nonabelian gauge theories, unitarity, optical theorem, Slavnov-Taylor identities, beta function of Yang-Mills theory, a heuristic derivation of asymptotic freedom, instantons in SU(N) gauge theory, theta vacua and the strong CP problem. 23 homework problems are included.

    ↳ hep-thhep-ph3 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.