Mon·Aug 24, 2020Monday·August 24, 2020

1. 01*

   QCD phase diagram and critical exponents within the nonextensive Polyakov-Nambu-Jona-Lasinio model

   Ya-Peng Zhao🇨🇳 · Shu-Yu Zuo🇨🇳 · Cheng-Ming Li🇨🇳

   We present a nonextensive version of the Polyakov-Nambu-Jona-Lasinio model which is based on the nonextentive statistical mechanics. This new statistics is characterized by a dimensionless nonextensivity parameter $q$ that accounts for all possible effects violating the assumptions of the Boltzmann-Gibbs (BG) statistics (when $q\to 1$, it returns to the BG case). Based on the nonextensive Polyakov-Nambu-Jona-Lasinio model, we discussed the influence of the nonextensive effects on the QCD phase transition, especially on the location of the critical end point (CEP). A new and interesting phenomenon we found is that with the increase of $q$, the CEP position initially shifted toward the direction of larger chemical potential and lower temperature. But then, when $q$ is greater than a critical value $q_c$, the CEP position moves in the opposite direction. In other words, as $q$ increases, the CEP position moves in the direction of smaller chemical potential and higher temperature. In addition, we calculated the influence of the nonextensive effects on the critical exponents and found that they remain almost constant with $q$.

   hep-phCPC(2021)·11 citations
2. 02*

   Revisiting fits to $B^0\to D^{\ast -}{\ell }^{+}{\nu }_{\ell }$ to measure $|V_{cb}|$ with novel methods and preliminary LQCD data at non-zero recoil

   Daniel Ferlewicz🇦🇺 · Phillip Urquijo🇦🇺 · Eiasha Waheed🇯🇵

   We present a study of fits to exclusive $B^0\to D^{\ast -}{\ell }^{+}{\nu }_{\ell }$ measurements for the determination of the Cabbibo-Kobayashi-Maskawa matrix element magnitude $|V_{cb}|$, based on the most recent Belle untagged measurement. Results are obtained with the Caprini-Lellouch-Neubert (CLN) and Boyd-Grinstein-Lebed (BGL) form factor parametrizations, with and without the inclusion of preliminary Lattice QCD measurements of form factors at non-zero hadronic recoil from the JLQCD collaboration. The CLN and BGL fits are also studied in different scenarios with reduced theoretical assumptions, and at higher order expansions, respectively. To avoid bias from high systematic error correlations we employ a novel technique in the field of $B$-physics phenomenology with a toy MC using a Cholesky decomposition of the covariance matrix. Using additional input from Lattice QCD calculations of form factors at non-zero recoil, in collaboration with JLQCD, allows for well-defined fit results with reduced model dependence in CLN and BGL. The results obtained are consistent between different configurations, ultimately providing a method for a more model-independent exclusive measurement of $|V_{cb}|$. Using preliminary inputs, $\mathcal{F}(1){\eta }_{\mathrm{EW}}|V_{cb}|$ is found to be approximately $(35.02\pm 0.29\pm 0.88)\times 10^{-3}$ in BGL(2,2,2) and $(34.96\pm 0.32\pm 0.96)\times 10^{-3}$ in CLNnoHQS.

   hep-phhep-exPRD(2021)·42 citations
3. 03*

   McMule -- QED Corrections for Low-Energy Experiments

   Yannick Ulrich🇨🇭

   We present McMule, a unified framework for the calculation of NLO and NNLO corrections to many processes in QED with massive fermions. This easily extendable program allows users to calculate an arbitrary observable for any of the processes implemented. These include various lepton decays as well as certain low-energy scattering experiments such as $e\mu \to e\mu$ and $\ell p\to \ell p$ that can be measured to high enough a precision to warrant QED corrections. As part of our discussion, we will present a pedagogical introduction to how these calculations are performed, focusing on technical aspects supplemented with examples. Our goal is to provide a useful introduction for those entering the field, covering all aspects relevant for the practitioner.

   hep-ph10 citations
4. 04*

   Efficient multi-jet merging with the Vincia sector shower

   Helen Brooks🇦🇺 · Christian T Preuss🇦🇺

   We here present an extension of the CKKW-L multi-jet merging technique to so-called sector showers as implemented in the Vincia antenna shower. The bijective nature of sector showers allows for efficient multi-jet merging at high multiplicities, as any given configuration possesses only a single "history", while retaining the accuracy of the CKKW-L technique. Our method reduces the factorial scaling of the number of parton shower histories to a constant of a single history per colour-ordered final state. We show that the complexity of constructing shower histories is reduced to an effective linear scaling with the number of final-state particles. Moreover, we demonstrate that the overall event generation time and the memory footprint of our implementation remain approximately constant when including additional jets. We compare both to the conventional CKKW-L implementation in Pythia and gain a first estimate of renormalisation scale uncertainties at high merged multiplicities. As a proof of concept, we show parton-level predictions for vector boson production in proton-proton collisions with up to nine hard jets using the new implementation. Despite its much simpler nature, we dub the new technique MESS, in analogy to the conventional MEPS nomenclature.

   hep-phComput.Phys.Commun.(2021)·21 citations
5. 05*

   Calculating the energy loss of leading jets

   Duff Neill🇺🇸 · Felix Ringer🇺🇸 · Nobuo Sato🇺🇸

   The energy loss mechanism of jets plays a central role in nuclear and high energy physics. We propose direct measurements of the energy loss of leading jets and perform a calculation at next-to-leading logarithmic (NLL${}^{\prime }$) accuracy in the vacuum. The formation of leading jets can be described by jet functions which constitute probability densities and thus allow for a perturbative calculation of the average the energy loss. We identify the following three criteria for a direct measurement of jet energy loss at the cross section level. $i)$ We measure a well defined object, the leading jet, where the formation process can be expressed in terms of a probability density. $ii)$ In addition, we need a measurement of a hard reference scale with respect to which jet energy loss is defined. $iii)$ At leading logarithmic accuracy, we require that the jet energy loss can be identified with parton energy loss. We discuss suitable observables and present numerical results including threshold corrections by making use of a parton shower Monte Carlo approach.

   hep-phhep-exnucl-exnucl-thPoS(2021)·1 citation
6. 06*

   $\psi$(4040) and $Y(4008)$ decay widths in hot and dense strange hadronic matter

   Rahul Chhabra🇮🇳

   In the present investigation, we evaluate the in-medium partial decay widths of exited states $\psi$(4040) and $Y$(4008) decaying to the pairs of non-strange pseudoscalar $D\bar{D}$ mesons, strange pseudoscalar $D_s{\bar{D}}_s$ mesons, non-strange vector $D^{\ast }{\bar{D}}^{\ast }$ meson and pseudoscalar-vector $D{\bar{D}}^{\ast }$ mesons using ${}^3{P}_0$ model. The in-medium effects are incorporated through the in-medium masses of daughter mesons (calculated using the chiral SU(3) model and QCD sum rule approach in our previous works). We consider $\psi$(4040) and $Y$(4008) states as 3${}^3{S}_1$ states and observe the in-medium dominance of one state over the other for a given decay mode. The results of the present investigation will prove as one step forward in assigning the correct spectroscopic state to controversial $Y$(4008) state.

   hep-ph0 citations
7. 07*

   Low-energy phenomenology of scalar leptoquarks at one-loop accuracy

   Valerio Gherardi🇮🇹 · David Marzocca🇮🇹 · Elena Venturini🇩🇪

   We perform a complete study of the low-energy phenomenology of $S_1$ and $S_3$ lepto-quarks, aimed at addressing the observed deviations in $B$-meson decays and the muon magnetic dipole moment. Leptoquark contributions to observables are computed at one-loop accuracy in an effective field theory approach, using the recently published complete one-loop matching of these leptoquarks to the Standard Model effective field theory. We present several scenarios, discussing in each case the preferred parameter space and the most relevant observables.

   hep-phhep-exJHEP(2021)·125 citations
8. 08*

   Pseudo-Goldstone dark matter: gravitational waves and direct-detection blind spots

   Tommi Alanne🇩🇪 · Nico Benincasa🇪🇪 · Matti Heikinheimo🇫🇮 · Kristjan Kannike🇪🇪 · Venus Keus🇫🇮 · Niko Koivunen🇪🇪 · Kimmo Tuominen🇫🇮

   Pseudo-Goldstone dark matter is a thermal relic with momentum-suppressed direct-detection cross section. We study the most general model of pseudo-Goldstone dark matter arising from the complex-singlet extension of the Standard Model. The new U(1) symmetry of the model is explicitly broken down to a CP-like symmetry stabilising dark matter. We study the interplay of direct-detection constraints with the strength of cosmic phase transitions and possible gravitational-wave signals. While large U(1)-breaking interactions can generate a large direct-detection cross section, there are blind spots where the cross section is suppressed. We find that sizeable cubic couplings can give rise to a first-order phase transition in the early universe. We show that there exist regions of the parameter space where the resulting gravitational-wave signal can be detected in future by the proposed Big Bang Observer detector.

   hep-phastro-ph.COJHEP(2020)·51 citations
9. 09*

   Exotic Higgs decays into displaced jets at the LHeC

   Kingman Cheung🇹🇼 · Oliver Fischer🇬🇧 · Zeren Simon Wang🇰🇷 · Jose Zurita🇩🇪

   Profiling the Higgs boson requires the study of its non-standard decay modes. In this work we discuss the prospects of the Large Hadron electron Collider (LHeC) to detect scalar particles with masses $\gtrsim$ 10 GeV produced from decays of the Standard Model (SM) Higgs boson. These scalar particles decay mainly to bottom pairs, and in a vast portion of the allowed parameter space they acquire a macroscopic lifetime, hence giving rise to displaced hadronic vertices. The LHeC provides a very clean environment that allows for easy identification of these final states, in contrast to hadronic colliders where the overwhelming backgrounds and high pile-up render such searches incredibly challenging. We find that the LHeC provides a unique window of opportunity to detect scalar particles with masses between 10 GeV and half the SM Higgs mass. In the Higgs Portal scenarios we can test the mixing angle squared, ${\sin }^2\alpha$, as low as $10^{-5}-10^{-7}$, with the exact value depending on the vacuum expectation value of the new scalar. Our results are also presented in a model-independent fashion in the lifetime-branching ratio and mass-branching ratio planes. We have found that exotic branching ratios of the Higgs boson at the sub-percent level can be probed, for the scalar decay length in the range $10^{-4}$ m $\lesssim c\tau \lesssim 10^{-1}$ m. The expected coverage of the parameter space largely exceeds the published sensitivity of the indirect reach at the high-luminosity Large Hadron Collider via the invisible Higgs branching ratio.

   hep-phJHEP(2021)·12 citations
10. 10*

    Distribution Amplitudes of Heavy Mesons and Quarkonia on the Light Front

    Fernando E. Serna🇧🇷 · Roberto Correa da Silveira🇧🇷 · J. J. Cobos-Martínez🇲🇽 · Bruno El-Bennich🇧🇷 · Eduardo Rojas🇨🇴

    The ladder kernel of the Bethe-Salpeter equation is amended by introducing a different flavor dependence of the dressing functions in the heavy-quark sector. Compared with earlier work this allows for the simultaneous calculation of the mass spectrum and leptonic decay constants of light pseudoscalar mesons, the $D_u$, $D_s$, $B_u$, $B_s$ and $B_c$ mesons and the heavy quarkonia ${\eta }_c$ and ${\eta }_b$ within the same framework at a physical pion mass. The corresponding Bethe-Salpeter amplitudes are projected onto the light front and we reconstruct the distribution amplitudes of the mesons in the full theory. A comparison with the first inverse moment of the heavy meson distribution amplitude in heavy quark effective theory is made.

    hep-phhep-exhep-latnucl-thEPJC(2020)·45 citations
11. 11*

    Phase transitions in the early universe

    Mark B. Hindmarsh🇫🇮 · Marvin Lüben🇩🇪 · Johannes Lumma🇩🇪 · Martin Pauly🇩🇪

    These lecture notes are based on a course given by Mark Hindmarsh at the 24th Saalburg Summer School 2018 and written up by Marvin Lüben, Johannes Lumma and Martin Pauly. The aim is to provide the necessary basics to understand first-order phase transitions in the early universe, to outline how they leave imprints in gravitational waves, and advertise how those gravitational waves could be detected in the future. A first-order phase transition at the electroweak scale is a prediction of many theories beyond the Standard Model, and is also motivated as an ingredient of some theories attempting to provide an explanation for the matter-antimatter asymmetry in our Universe. Starting from bosonic and fermionic statistics, we derive Boltzmann's equation and generalise to a fluid of particles with field dependent mass. We introduce the thermal effective potential for the field in its lowest order approximation, discuss the transition to the Higgs phase in the Standard Model and beyond, and compute the probability for the field to cross a potential barrier. After these preliminaries, we provide a hydrodynamical description of first-order phase transitions as it is appropriate for describing the early Universe. We thereby discuss the key quantities characterising a phase transition, and how they are imprinted in the gravitational wave power spectrum that might be detectable by the space-based gravitational wave detector LISA in the 2030s.

    ↳ astro-ph.COgr-qchep-phSciPost Phys.Lect.Notes(2021)·355 citations
12. 12*

    Dark photon search with a gyrotron and a transition edge sensor

    A. Miyazaki🇸🇪 · P. Spagnolo🇮🇹

    A dark photon, one of the candidates of light dark matter, will be searched around 0.1 meV range by using a gyrotron. The use of a Transition Edge Sensor is the key of this experiment and the expected result is promising. This search will pave a way to future axion search using similar instruments.

    ↳ hep-exastro-ph.IMhep-phphysics.ins-det1 citation
13. 13*

    One dimensional nexus objects, network of Kibble-Lazarides-Shafi string walls, and their spin dynamic response in polar distorted B-phase of ${}^3$He

    K. Zhang🇫🇮

    The Kibble-Lazarides-Shafi (KLS) domain wall problem in the axion solution of CP violation in QCD has condensed-matter based analogy in the nafen-distorted superfluid ${}^3$He. Recent experiment in rotating superfluid ${}^3$He produced the network of KLS string walls in human controllable system. In this system, KLS string wall appears in two-step symmetry break transition from normal phase to polar-distorted B phase and turn out to be the descendants of HQVs of polar phase. Here we show the KLS string wall smoothly connects to spin solitons when the spin orbital coupling is taken into account. This means HQVs are 1D nexus which connects the spin solitons and the KLS domain walls. This is because the subgroup $G={\pi }_1(S_S^1,{\tilde{R}}_2)$ of relative homotopy group describing the spin solitons is isomorphic to the group describing the half spin vortices -- the spin textures KLS string wall. In the nafen-distorted ${}^3$He system, 1D nexus objects and the spin solitons with topological invariant $2/4$ form two different types of network, which are named as pseudo-random lattices of inseparable and separable spin solitons. These two types lattices correspond to two different representations of $G$. We discuss the condition under which pseudo-random lattices model works. The equilibrium configuration and surface densities of free energies are calculated by numeric minimization. Based on the equilibrium spin textures of different pseudo-random lattices, we calculated their transverse NMR spectrum, the resulted frequency shifts and $\sqrt{\Omega }$-scaling of ratio intensity exactly coincide with the experimental measurements. We also discussed the mirror symmetry in the presence of KLS domain wall and the influence of the explicitly break of this discrete symmetry. Our discussions and considerations can be applied to the composite defects in other condensed matter and cosmological system.

    ↳ cond-mat.mes-hallastro-ph.COcond-mat.dis-nncond-mat.supr-con+1PRResearch(2020)·8 citations
14. 14*

    Four-loop singularities of the massless fermion propagator in quenched three-dimensional QED

    A. F. Pikelner🇷🇺 · V. P. Gusynin🇺🇦 · A. V. Kotikov🇷🇺 · S. Teber🇫🇷

    We calculate the three- and four-loop corrections to the massless fermion propagator in three-dimensional quenched Quantum Electrodynamics with four-component fermions. The three-loop correction is finite and gauge invariant but the four-loop one has singularities except in the Feynman gauge where it is also finite. Our results explicitly show that, up to four loops, gauge-dependent terms are completely determined by lower order ones in agreement with the Landau-Khalatnikov-Fradkin transformation.

    ↳ hep-thcond-mat.str-elhep-phPRD(2020)·7 citations
15. 15*

    LREE of a Dynamical Unstable D$p$-brane

    Shirin Teymourtashlou🇮🇷 · Davoud Kamani🇮🇷

    We derive the left-right entanglement entropy (LREE) for a bosonic D$p$-brane. This brane has tangential dynamics and has been dressed by a $U(1)$ gauge potential, the Kalb-Ramond field and a tachyon field. For this purpose, the Rényi entropy will be computed and then, by taking a special limit of it, the LREE will be obtained. Besides, the behavior of the LREE under the tachyon condensation process will be evaluated. In addition, after the transition of the system, i.e. the collapse of the unstable brane, the second law of the thermodynamics on the LREE will be checked. We find that preserving the second law imposes some conditions on the parameters of the setup.

    ↳ hep-thhep-phNPB(2020)·2 citations
16. 16*

    Implications of the $S_8$ tension for decaying dark matter with warm decay products

    Guillermo Franco Abellán🇫🇷 · Riccardo Murgia🇫🇷 · Vivian Poulin🇫🇷 · Julien Lavalle🇫🇷

    Recent weak lensing surveys have revealed that the direct measurement of the parameter combination $S_8\equiv {\sigma }_8({\Omega }_m/0.3{)}^{0.5}$ -- where ${\sigma }_8$ is a measure of the amplitude of matter fluctuations on 8 $h^{-1}$Mpc scales -- is $\sim 3\sigma$ discrepant with the value reconstructed from cosmic microwave background (CMB) data assuming the $\Lambda$CDM model. In this article, we show that it is possible to resolve the tension if dark matter (DM) decays with a lifetime of ${\Gamma }^{-1}\simeq 55\text{Gyrs}$ into one massless and one massive product, and transfers a fraction $\epsilon \simeq 0.7\%$ of its rest mass energy to the massless component. The velocity-kick received by the massive daughter leads to a suppression of gravitational clustering below its free-streaming length, thereby reducing the ${\sigma }_8$ value as compared to that inferred from the standard $\Lambda$CDM model, in a similar fashion to massive neutrino and standard warm DM. Contrarily to the latter scenarios, the time-dependence of the power suppression and the free-streaming scale allows the 2-body decaying DM scenario to accommodate CMB, baryon acoustic oscillation, growth factor and un-calibrated supernova Ia data. We briefly discuss implications for DM model building, galactic small-scale structure problems and the recent Xenon-1T excess. Future experiments measuring the growth factor to high accuracy at $0\lesssim z\lesssim 1$ can further test this scenario.

    ↳ astro-ph.COhep-phPRD(2022)·94 citations
17. 17*

    Is the local Lorentz invariance of general relativity implemented by gauge bosons that have their own Yang-Mills-like action?

    Kevin Cahill🇺🇸

    General relativity with fermions has two independent symmetries: general coordinate invariance and local Lorentz invariance. General coordinate invariance is implemented by the Levi-Civita connection and by Cartan's tetrads both of which have as their action the Einstein-Hilbert action. It is suggested here that local Lorentz invariance is implemented not by a combination of the Levi-Civita connection and Cartan's tetrads known as the spin connection, but by independent Lorentz bosons L_i that gauge the Lorentz group, that couple to fermions like Yang-Mills fields, and that have their own Yang-Mills-like action. A nonsingular 4 x 4 hermitian scalar field h is needed to make the action of the Lorentz bosons invariant under local Lorentz transformations. Lorentz bosons couple to fermion number and generate a spin-dependent static potential that violates the weak equivalence principle. If a Higgs mechanism makes them massive, then the static potential also violates the inverse-square law. Experiments put upper bounds on the strength of such a potential for masses m_L < 20 eV. These upper limits imply that Lorentz bosons, if they exist, are nearly stable and contribute to dark matter.

    ↳ gr-qchep-phhep-thPRD(2020)·5 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.