Wed·Oct 28, 2020Wednesday·October 28, 2020

1. 01*

   On the stability of the open-string QED neutron and dark matter

   Cheuk-Yin Wong🇺🇸

   We study the stability of a hypothetical QED neutron, which consists of a color-singlet system of two $d$ quarks and a $u$ quark interacting with the QED interaction. As a quark cannot be isolated, the intrinsic motion of the three quarks in the lowest-energy state may lie predominantly in 1+1 dimensions, as in a $d$-$u$-$d$ open string. The attractive $d$-$u$ and $u$-$d$ QED interactions may overcome the weaker repulsive $d$-$d$ QED interaction to bind the three quarks together. We examine the QED neutron in a phenomenological three-body problem in 1+1 dimensions with an effective interaction extracted from Schwinger's exact QED solution in 1+1 dimensions. The phenomenological model in a variational calculation yields a stable QED neutron at 44.5 MeV. The analogous QED proton with two $u$ quarks and a $d$ quark has been found to be too repulsive to be stable and does not have a bound or continuum state, onto which the QED neutron can decay via the weak interaction. Consequently, the QED neutron is stable against the weak decay, has a long lifetime, and is in fact a QED dark neutron. It may be produced following the deconfinement-to-confinement phase transition of the quark gluon plasma in high-energy heavy-ion collisions. Because of the long lifetime of the QED dark neutron, self-gravitating assemblies of QED dark neutrons or dark antineutrons may be good candidates for a part of the primordial dark matter produced during the phase transition of the quark gluon plasma in the evolution of the early Universe.

   hep-phnucl-thEPJA(2022)·9 citations
2. 02*

   Ghosts in the Wall

   Christopher D. Carone🇺🇸

   We consider the possibility of an axion-like particle (ALP) that is a ghost, with wrong-sign kinetic and mass terms. Such an ALP can arise as the partner to an ordinary particle in theories with higher-derivative quadratic terms. We compute the photon regeneration probability in light-shining-through-wall experiments and show that the presence of such a ghostly ALP can lead, in principle, to discernible effects.

   hep-phPRD(2020)·0 citations
3. 03*

   Production of massless charm jets in $pp$ collisions at next-to-leading order of QCD in comparison with CMS data

   Gustav Kramer🇩🇪

   We present predictions for the inclusive production of charm jets in proton-proton collisions at 2.76 and 5.02 TeV. The charm-quark is considered massless. In this scheme we find that the ratio of the next-to-leading order to the leading order cross section (K factor) is almost equal to one depending essentially on the choice of the renormalization and factorization scale. Adding non-pertubative corrections obtained from Pythia Monte Carlo calculations lead to reasonable agreement with experimental c-jet cross sections obtained by the CMS collaboration.

   hep-phhep-ex0 citations
4. 04*

   Search for electric dipole moment

   V. G. Baryshevsky🇧🇾 · P. I. Porshnev🇧🇾

   The outstanding progress has been made in reducing the upper bounds on EDM of several particles. Even if significant challenges must be overcome to further improve these limits, it is still one of the best chances to detect new type of interactions beyond the standard model. Analyzing several examples, we highlight a common thread that is visible in different set-ups used for the EDM detection. The electric dipole moment is one of the clear consequences of CP- or T-violating interactions, however it is not the only one. These symmetry-violating interactions enable extra phenomena that unavoidably accompany the EDM-induced spin precession, and they must be taken into account in planning and executing sensitive experiments. After reviewing three typical cases, we suggest conditions for improving the sensitivity of detecting the intrinsic EDM.

   hep-ph2 citations
5. 05*

   Dark matter constraints and the neutralino sector of the scNMSSM

   Elham Aldufeery🇸🇦 · Maien Binjonaid🇸🇦

   The neutralino sector of the semi-constrained next-to-minimal supersymmetric standard model is explored under recent experimental constraints, with special attention to dark matter (DM) limits. The effects of the upper and lower bounds of dark matter relic density and recent direct detection constraints on spin-independent and -dependent cross-sections are thoroughly analyzed. Particularly, we show which regions of the parameter space are ruled out due to the different dark matter constraints and the corresponding model-specific parameters: $\lambda ,\kappa ,A_{\lambda }$, and $A_{\kappa }$. We analyze all annihilation and co-annihilation processes (with heavier neutralinos and charginos) that contribute to the dark matter relic density. The mass components of the dark matter candidate, the lightest neutralino ${\tilde{\chi }}_1^0$, are studied, and the decays of heavy neutralinos and charginos, especially ${\tilde{\chi }}_2^0$ and ${\tilde{\chi }}_1^{+}$, into the lightest neutralino are examined. We impose semi-universal boundary conditions at the Grand Unified Theory scale and require a moderate range of $\tan \beta \lesssim 10$. We find that the allowed parameter space is associated with a heavy mass spectrum in general and that the lightest neutralino is mostly Higgsino with a mass range that resides mostly between 1000 and 1500 GeV. However, smaller mass values can be achieved if the DM candidate is bino-like or singlino-like.

   hep-phUniverse(2021)·6 citations
6. 06*

   An Analysis of Parton Distribution Functions of the Pion and the Kaon with the Maximum Entropy Input

   Chengdong Han🇨🇳 · Gang Xie🇨🇳 · Rong Wang🇨🇳 · Xurong Chen🇨🇳

   We present pion and kaon parton distribution functions from a global QCD analysis of the experimental data within the framework of dynamical parton model. We use the DGLAP equations with parton-parton recombination corrections and the valence input of uniform distribution which maximizes the information entropy. At our input scale $Q_0^2$, there are no sea quark and gluon distributions. All the sea quarks and gluons of the pion and the kaon are completely generated from the parton splitting processes. The mass-dependent parton splitting kernel is applied for the strange quark distribution in the kaon. The obtained valence quark and sea quark distributions at high $Q^2$ ($Q^2>5$ GeV${}^2$) are compatible with the existed experimental measurements. Furthermore, the asymptotic behaviours of parton distribution functions at small and large $x$ have been studied for both the pion and the kaon. Lastly, the first three moments of parton distributions at high $Q^2$ scale are calculated, which are consistent with other theoretical predictions.

   hep-phEPJC(2021)·42 citations
7. 07*

   Corrections of order O(E^2_e/m^2_N), caused by weak magnetism and proton recoil, to the neutron lifetime and correlation coefficients of the neutron beta decay

   A. N. Ivanov🇦🇹 · R. Höllwieser🇦🇹 · N. I. Troitskaya🇦🇹 · M. Wellenzohn🇦🇹 · Ya. A. Berdnikov🇷🇺

   We calculate the contributions of weak magnetism and proton recoil of order O(E^2_e/m^2_N)~10^{-5}, i.e. to next-to-next-to-leading order in the large nucleon mass expansion, to the neutron lifetime and correlation coefficients of the neutron beta decay, where E_e and m_N are the electron energy and the nucleon mass, respectively. We analyze the electron-energy and angular distribution for the neutron beta decay with a polarized neutron, a polarized electron and an unpolarized proton. Together with Wilkinson's corrections (Nucl. Phys. A 377, 474 (1982) and radiative corrections of order O(alpha E_e/m_N) ~ 10^{-5} (Phys. Rev. D 99, 093006 (2019)), calculated as next--to--leading order corrections in the large nucleon mass $m_N$ expansion to Sirlin's corrections of order O(alpha/pi) (Phys. Rev. 164, 1767 (1967)), the corrections of order O(E^2_e/m^2_N) ~ 10^{-5} provide an improved level of precision of the theoretical background of the neutron beta decay, calculated in the Standard Model, for experimental searches of contributions of interactions beyond the Standard Model.

   hep-phnucl-exResults Phys.(2021)·13 citations
8. 08*

   Study on ${\eta }_{c2}({\eta }_{b2})$ electromagnetic decay into double photons

   Li Yang🇨🇳 · Wen-Long Sang🇨🇳 · Hong-Fei Zhang🇨🇳 · Yu-Dong Zhang🇨🇳 · Ming-Zhen Zhou🇨🇳

   Within the framework of nonrelativistic QCD (NRQCD) factorization formalism, we compute the helicity amplitude as well as the decay width of ${\eta }_{Q2}$ ($Q=c,b$) electromagnetic decay into two photons up to next-to-next-to-leading order (NNLO) in ${\alpha }_s$ expansion. For the first time, we verify the validity of NRQCD factorization for the D-wave quarkonium decay at NNLO. We find that the $\mathcal{O}({\alpha }_s)$ and $\mathcal{O}({\alpha }_s^2)$ corrections to the helicity amplitude are negative and moderate, nevertheless both corrections combine to suppress the leading-order prediction for the decay width significantly. By approximating the total decay width of ${\eta }_{Q2}$ as the sum of those for the hadronic decay and the electric $E1$ transition, we obtain the branching ratios $\mathrm{Br}({\eta }_{c2}\to 2\gamma )\approx 5\times 10^{-6}$ and $\mathrm{Br}({\eta }_{b2}\to 2\gamma )\approx 4\times 10^{-7}$. To explore the potential measurement on ${\eta }_{Q2}$, we further evaluate the production cross section of ${\eta }_{Q2}$ at LHCb at the lowest order in ${\alpha }_s$ expansion. With the kinematic constraint on the longitudinal rapidity $4.5>y>2$ and transverse momentum $P_T>(2-4)m_Q$ for ${\eta }_{Q2}$, we find the cross section can reach $2-50$ nb for ${\eta }_{c2}$, and $1-22$ pb for ${\eta }_{b2}$. Considering the integrated luminosity $\mathcal{L}=10{\mathrm{fb}}^{-1}$ at $\sqrt{s}=7$ TeV and $\sqrt{s}=13$ TeV, we estimate that there are several hundreds events of $pp\to {\eta }_{c2}\to 2\gamma$. Since the background is relatively clean, it is promising to reconstruct ${\eta }_{c2}$ through its electromagnetic decay. On the contrary, due to small branching ratio and production cross section, it is quite challenging to detect ${\eta }_{b2}\to 2\gamma$ at LHCb.

   hep-phPRD(2021)·8 citations
9. 09*

   Laser effect on the final products of $Z$-boson decay

   M. Jakha🇲🇦 · S. Mouslih🇲🇦 · S. Taj🇲🇦 · B. Manaut🇲🇦

   Experimentalists have long sought a method that allows them to control as they like the branching ratios of an unstable particle decay and direct some decay to follow one specific desired channel without another. The powerful laser could make this dream come true. In this Letter and within the framework of the standard electroweak model, we investigate theoretically the laser effect on the branching ratios of different $Z$-boson decay modes by calculating analytically the $Z$-boson decay into a pair of fermion-antifermion $(Z\to f\bar{f})$ in the presence of a circularly polarized electromagnetic field. It is found that, at high intensities, the $Z$-boson could only decay invisibly into neutrinos, and its decay into any other pair of charged fermions becomes impossible due to the increase in the effective mass that fermions acquire inside the electromagnetic field. The influence of the laser frequency and intensity on the lifetime is also included in order to confirm the surprising result obtained for the pion lifetime in a previous paper [ Mouslih S \textit{et al} 2020 \textit{Phys. Rev. D} \textbf{102} 073006 ].

   hep-phLaser Phys.Lett.(2021)·28 citations
10. 10*

    Laser-Assisted Pion Decay

    S. Mouslih🇲🇦 · M. Jakha🇲🇦 · S. Taj🇲🇦 · B. Manaut🇲🇦 · E. Siher🇲🇦

    This paper revives the controversial debate that has arisen over the last two decades about the possibility that the electromagnetic field affects the lifetime or the decay rate of an unstable particle. In this research, we show, by performing analytical calculations and extracting numerical results, that the pion lifetime can be changed notably by inserting the decaying pion into an electromagnetic field only if the number of photons transferred between the decaying system and the laser field does not reach the well-known sum-rule. The influence of the laser parameters on the decay rate and branching ratio is also discussed. The surprising result obtained for the pion lifetime is referred to as the well-known quantum Zeno effect.

    hep-phPRD(2020)·35 citations
11. 11*

    Bounds on Plack-scale deformation of CPT from lifetimes and interference

    Wojciech Wislicki🇵🇱

    Deformed relativistic kinematics, expected to emerge in a flat-spacetime limit of quantum gravity, predicts violation of discrete symmetries at energy scale in the vicinity of the Planck mass. Momentum-dependent deformations of the C, P and T invariance are derived from the ąppa}-deformed Poincaré algebra. Deformation of the CPT symmetry leads to a subtle violation of Lorentz symmetry. This entails some small but measurable phenomenological consequences, as corrections to characteristics of time evolution: particle lifetimes or frequency of flavour oscillations in two-particle states at high energy. We argue here that using current experimental precisions on the muon lifetime one can bound the deformation parameter ąppa} > 10^14 GeV at LHC energy and move this limit even to 10^16 GeV at Future Circular Collider, planned at CERN. Weaker limits on deformation can be also obtained from interference of neutral mesons. In case of B0s from {\Upsilon} decay it amounts to ąppa} > 10^8 GeV at confidence level 99%.

    hep-phgr-qcPoS(2020)·0 citations
12. 12*

    In Pursuit of New Physics with $B_d^0\to J/\psi K^0$ and $B_s^0\to J/\psi \varphi$ Decays at the High-Precision Frontier

    Marten Z. Barel🇳🇱 · Kristof De Bruyn🇳🇱 · Robert Fleischer🇳🇱 · Eleftheria Malami🇳🇱

    The decays $B_d^0\to J/\psi K_{\text{S}}^0$and $B_s^0\to J/\psi \varphi$ play a key role for the determination of the $B_q^0$-${\bar{B}}_q^0$ ($q=d,s$) mixing phases ${\varphi }_d$ and ${\varphi }_s$, respectively. The theoretical precision of the extraction of these quantities is limited by doubly Cabibbo-suppressed penguin topologies, which can be included through control channels by means of the $SU(3)$ flavour symmetry of strong interactions. Using the currently available data and a new simultaneous analysis, we discuss the state-of-the-art picture of these effects and include them in the extracted ${\varphi }_q$ values. We have a critical look at the Standard Model predictions of these phases and explore the room left for new physics. Considering future scenarios for the high-precision era of flavour physics, we illustrate that we may obtain signals for physics beyond the Standard Model with a significance well above five standard deviations. We also determine effective colour-suppression factors of $B_d^0\to J/\psi K^0$, $B_d^0\to J/\psi K_{\text{S}}^0$ and $B_d^0\to J/\psi {\pi }^0$ decays, which serve as benchmarks for QCD calculations of the underlying decay dynamics, and present a new method using information from semileptonic $B_d^0\to {\pi }^{-}{\ell }^{+}{\nu }_{\ell }$ and $B_s^0\to K^{-}{\ell }^{+}{\nu }_{\ell }$ decays.

    hep-phJ.Phys.G(2021)·61 citations
13. 13*

    Gluodynamics and deconfinement phase transition under rotation from holography

    Xun Chen🇨🇳 · Lin Zhang🇨🇳 · Danning Li🇨🇳 · Defu Hou🇨🇳 · Mei Huang🇨🇳

    We investigate rotating effect on deconfinement phase transition in an Einstein-Maxwell-Dilaton(EMD) model in bottom-up holographic QCD approach. By constructing a rotating black hole, which is supposed to be dual to rotating strongly coupled nuclear matter, we investigate the thermodynamic quantities, including entropy density, pressure, energy density, trace anomaly, sound speed and specific heat for both pure gluon system and two-flavor system under rotation. It is shown that those thermodynamic quantities would be enhanced by large angular velocity. Also, we extract the information of phase transition from those thermodynamic quantities, as well as the order parameter of deconfinement phase transition, i.e. the loop operators. It is shown that, in the $T-\omega$ plane, for two-flavor case with small chemical potential, the phase transition is always crossover. The transition temperature decreases slowly with angular velocity and chemical potential. For pure gluon system with zero chemical potential, the phase transition is always first order, while at finite chemical potential a critical end point(CEP) will present in the $T-\omega$ plane.

    hep-phJHEP(2021)·150 citations
14. 14*

    Analytic integration of soft and collinear radiation in factorised QCD cross sections at NNLO

    Lorenzo Magnea🇨🇭 · Giovanni Pelliccioli🇩🇪 · Chiara Signorile-Signorile🇮🇹 · Paolo Torrielli🇮🇹 · Sandro Uccirati🇮🇹

    Within the framework of local analytic sector subtraction, we present the full analytic integration of double-real and real-virtual local infrared counterterms that enter NNLO QCD computations with any number of massless final-state partons. We show that a careful choice of phase-space mappings leads to simple analytic results, including non-singular terms, that can be obtained with conventional integration techniques.

    hep-phJHEP(2021)·40 citations
15. 15*

    Combined Explanation of the $Z\to b\bar{b}$ Forward-Backward Asymmetry, the Cabibbo Angle Anomaly, $\tau \to \mu \nu \nu$ and $b\to s{\ell }^{+}{\ell }^{-}$ Data

    Andreas Crivellin🇨🇭 · Claudio Andrea Manzari🇨🇭 · Marcel Alguero🇪🇸 · Joaquim Matias🇪🇸

    In this article we propose a simple model which can provide a combined explanation of the $Z\to b\bar{b}$ forward-backward asymmetry, the Cabibbo Angle Anomaly (CAA), $\tau \to \mu \nu \nu$ and $b\to s{\ell }^{+}{\ell }^{-}$ data. This model is obtained by extending the Standard Model (SM) by two heavy vector-like quarks (an $SU(2{)}_L$ doublet (singlet) with hypercharge $-5/6$ (-1/3)), two new scalars (a neutral and a singly charged one) and a gauged $L_{\mu }-L_{\tau }$ symmetry. The mixing of the new quarks with the SM ones, after electroweak symmetry breaking, does not only explain $Z\to b\bar{b}$ data but also generates a lepton flavour universal contribution to $b\to s{\ell }^{+}{\ell }^{-}$ transitions. Together with the lepton flavour universality violating effect, generated by loop-induced $Z^{\prime }$ penguins involving the charged scalar and the heavy quarks, it gives an excellent fit to data ($6.1\sigma$ better than the SM). Furthermore, the charged scalar (neutral vector) gives a necessarily constructive tree-level (loop) effect in $\mu \to e\nu \nu$ ($\tau \to \mu \nu \nu$), which can naturally account for the CAA ($\mathrm{Br}[\tau \to \mu \nu \nu ]/\mathrm{Br}[\tau \to e\nu \nu ]$ and $\mathrm{Br}[\tau \to \mu \nu \nu ]/\mathrm{Br}[\mu \to e\nu \nu ]$).

    hep-phhep-exnucl-exnucl-thPRL(2021)·67 citations
16. 16*

    Resonant Sub-GeV Dirac Dark Matter

    Elias Bernreuther🇩🇪 · Saniya Heeba🇩🇪 · Felix Kahlhoefer🇩🇪

    We study the phenomenology and detection prospects of a sub-GeV Dirac dark matter candidate with resonantly enhanced annihilations via a dark photon mediator. The model evades cosmological constraints on light thermal particles in the early universe while simultaneously being in reach of current and upcoming terrestrial experiments. We conduct a global analysis of the parameter space , considering bounds from accelerator and direct detection experiments, as well as those arising from Big Bang Nucleosynthesis, the Cosmic Microwave Background and dark matter self-interactions. We also extend our discussion to the case of a dark matter subcomponent. We find that large regions of parameter space remain viable even for the case of a moderate resonant enhancement, and demonstrate the complementarity of different experimental strategies for further exploring this scenario.

    hep-phastro-ph.COJCAP(2021)·40 citations
17. 17*

    Two-Loop Five-Parton Leading-Colour Finite Remainders in the Spinor-Helicity Formalism

    Giuseppe De Laurentis🇩🇪 · Daniel Maître🇬🇧

    We present all two-loop five-parton leading-colour finite remainders in the spinor-helicity formalism by analysing numerical evaluations of their known expressions in terms of Mandelstam invariants. Recasting them in terms of spinor-helicity variables allows us to obtain expressions which are more compact, faster to evaluate, numerically more stable and manifestly free from poles of higher order than necessary. At the same time, due to the better scaling of our reconstruction strategy with the complexity of the input, we required one order of magnitude fewer numerical samples to complete the analytical reconstruction than were needed by the authors of Ref. \cite{Abreu:2019odu}, albeit using higher numerical working precision. This places our reconstruction technique as an alternative to the finite-field single-numerator reconstruction for future applications.

    hep-phJHEP(2021)·30 citations
18. 18*

    Hadron structure and spin effects in elastic hadron scattering at NICA energies

    O.V. Selyugin🇷🇺

    The spin effects in the elastic proton-proton scattering are analysed at NICA energies. It is shown the importance the investigation of the region of the diffraction minimum in the differential cross sections. Some possible estimation of spin effects are given for the different NICA energies in the framework of the new high energy generelazed structure (HEGS) model.

    hep-phhep-ex2 citations
19. 19*

    Nested sampling with plateaus

    Andrew Fowlie🇨🇳 · Will Handley🇬🇧 · Liangliang Su🇨🇳

    It was recently emphasised by Riley (2019); Schittenhelm & Wacker (2020) that that in the presence of plateaus in the likelihood function nested sampling (NS) produces faulty estimates of the evidence and posterior densities. After informally explaining the cause of the problem, we present a modified version of NS that handles plateaus and can be applied retrospectively to NS runs from popular NS software using anesthetic. In the modified NS, live points in a plateau are evicted one by one without replacement, with ordinary NS compression of the prior volume after each eviction but taking into account the dynamic number of live points. The live points are replenished once all points in the plateau are removed. We demonstrate it on a number of examples. Since the modification is simple, we propose that it becomes the canonical version of Skilling's NS algorithm.

    ↳ stat.COastro-ph.IMhep-phphysics.data-anMNRAS(2021)·11 citations
20. 20*

    Baryogenesis through Asymmetric Hawking Radiation from Primordial Black Holes as Dark Matter

    Alexis Boudon🇨🇭 · Benjamin Bose🇨🇭 · Hyat Huang🇨🇳 · Lucas Lombriser🇨🇭

    We examine the extent to which primordial black holes (PBHs) can constitute the observed dark matter while also giving rise to the measured matter-antimatter asymmetry and account for the observed baryon abundance through asymmetric Hawking radiation generated by a derivative coupling of curvature to the baryon-lepton current. We consider both broad and monochromatic mass spectra for this purpose. For the monochromatic spectrum we find that the correct dark matter and baryon energy densities are recovered for peak masses of the spectrum of $M_{\mathrm{pk}}\ge 10^{12}$ kg whereas for the broad case the observed energy densities can be reproduced regardless of peak mass. Adopting some simplifications for the early-time expansion history as a first approximation, we also find that the measured baryon asymmetry can be recovered within an order of magnitude. We argue furthermore that the correct value of the baryon-lepton yield can in principle be retrieved for scenarios where a significant amount of the radiation is produced by PBH decay during or after reheating, as is expected when the decaying PBHs also cause reheating, or when an early matter-dominated phase is considered. We conclude from this first analysis that the model merits further investigation.

    ↳ astro-ph.COhep-phPRD(2021)·20 citations
21. 21*

    Jet transport coefficient $\hat{q}$ in lattice QCD

    Amit Kumar (Wayne State University and McGill University)🇺🇸 · Abhijit Majumder (Wayne State University)🇺🇸 · Johannes Heinrich Weber (Michigan State University and Humboldt University of Berlin)🇺🇸

    We present the first calculation of the jet transport coefficient $\hat{q}$ in quenched and (2+1)-flavor QCD on a 4-D Euclidean lattice. The light-like propagation of an energetic parton is factorized from the mean square gain in momentum transverse to the direction of propagation, which is expressed in terms of the thermal field-strength field-strength correlator. The leading-twist term in its operator product expansion is calculated on the lattice. Continuum extrapolated quenched results, and full QCD estimates based on un-renormalized lattice data, over multiple lattice sizes, are compared with (non) perturbative calculations and phenomenological extractions of $\hat{q}$. The lattice data for $\hat{q}$ show a temperature dependence similar to the entropy density. Within uncertainties, these are consistent with phenomenological extractions, contrary to calculations using perturbation theory.

    ↳ hep-lathep-phnucl-exnucl-thPRD(2022)·41 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.