Tue·Sep 10, 2019Tuesday·September 10, 2019

1. 01*

   A guide for deploying Deep Learning in LHC searches: How to achieve optimality and account for uncertainty

   Benjamin Nachman🇺🇸

   Deep learning tools can incorporate all of the available information into a search for new particles, thus making the best use of the available data. This paper reviews how to optimally integrate information with deep learning and explicitly describes the corresponding sources of uncertainty. Simple illustrative examples show how these concepts can be applied in practice.

   hep-phhep-exphysics.data-anSciPost Phys.(2020)·63 citations
2. 02*

   Magnetic transitions and radiative decays of singly heavy baryons

   Ghil-Seok Yang🇰🇷 · Hyun-Chul Kim🇰🇷

   A pion mean-field approach allows one to investigate light and singly heavy baryons on an equal footing. In the large $N_c$ limit, the light and singly heavy baryons are viewed respectively as $N_c$ and $N_c-1$ valence quarks bound by the pion mean fields created self-consistently, since a heavy quark can be regarded as a static color source in the limit of the infinitely heavy quark mass. The transition magnetic moments of the baryon sextet are determined entirely by using the parameters fixed in the light-baryon sector without any additional parameters introduced. Assuming that the transition $E2$ moments are small, we are able to compute the radiative decay rates of the baryon sextet. The numerical results are discussed, being compared with those from other approaches.

   hep-phhep-exPLB(2020)·29 citations
3. 03*

   Aspects of isentropic trajectories in chiral effective models

   Rainer Stiele🇮🇹 · Wanda Maria Alberico🇮🇹 · Andrea Beraudo🇮🇹 · Renan Câmara Pereira🇵🇹 · Pedro Costa🇵🇹 · Hubert Hansen🇫🇷 · Mario Motta🇮🇹

   The evolution of the fireball in heavy ion collisions is an isentropic process, meaning that it follows a trajectory of constant entropy per baryon in the phase diagram of the strong interaction. Responsible for the collective acceleration of the fireball is the speed of sound of the system, while fluctuations of conserved charges are encoded in quark-number susceptibilities: together, they leave their imprint in final observables. Here, this isentropic evolution will be analysed within chiral effective models that account for both chiral and center symmetry breaking, two central aspects of QCD. Our discussion focusses on the impact on the isentropic trajectories of the treatment of high-momentum modes, of the meson contribution to thermodynamics and of the number of quark flavours.

   hep-phnucl-thJ.Phys.Conf.Ser.(2020)·0 citations
4. 04*

   Nucleon resonances with spin $\frac{3}{2}$ and isospin $\frac{1}{2}$

   K. Azizi🇮🇷 · Y. Sarac🇹🇷 · H. Sundu🇹🇷

   Investigation of the nucleon's excited states has always become an important research topic because of the rich information they provide. Since their first observation, dating back about 70 years, the investigation of their various parameters contributed both to the development of the quark model and better understanding of the QCD as the theory of strong interaction. Their investigation still has importance. The researches conducted on the nucleon excited states are helpful to probe missing resonances predicted by the quark model but not observed yet. With this motivation, we study the low lying nucleon resonance with $I(J^P)=\frac{1}{2}({\frac{3}{2}}^{-})$ and its corresponding orbital and radial excitations with $I(J^P)=\frac{1}{2}({\frac{3}{2}}^{+})$ and $I(J^P)=\frac{1}{2}({\frac{3}{2}}^{-})$, respectively. Using the QCD sum rule method, we calculate the masses and pole residues of these states. The obtained mass results are consistent with the mass ranges presented in PDG for the resonances $N^{\ast }(1520)(3/2^{-})$, $N^{\ast }(1700)(3/2^{-})$, and $N^{\ast }(1720)(3/2^{+})$. The results of masses and residues of these states may be used as input parameters to calculate various quantities related to their electromagnetic, weak and strong interactions with other particles with the aim of getting more information on their nature and structure.

   hep-phhep-exhep-latJ.Phys.G(2020)·6 citations
5. 05*

   Form Factors and Decay of ${\bar{B}}_s^0\to J/\psi \varphi$ From QCD Sum Rule

   Ying-Quan Peng🇨🇳 · Mao-Zhi Yang🇨🇳

   We calculate ${\bar{B}}_s^0\to \varphi$ translation form factors $V$, $A_0$, $A_1$, $A_2$ based on QCD sum rule and study the nonleptonic two-body decay of ${\bar{B}}_s^0\to J/\psi \varphi$ with the form factors obtained. We calculate the time-integrated branching ratio of ${\bar{B}}_s^0\to J/\psi \varphi$ decay. The results for both the total branching ratio and the cases for the final vectors in longitudinal and transverse polarizations are consistent with experimental data.

   hep-phMod.Phys.Lett.A(2020)·5 citations
6. 06*

   Correlations in flavor-changing tqZ couplings constrained via experimental data

   Zenro Hioki (U. Tokushima)🇯🇵 · Kazumasa Ohkuma (Okayama U. Science)🇯🇵 · Akira Uejima (Okayama U. Science)🇯🇵

   Possible non-standard tqZ couplings, where q=c or u, originated from general flavor-changing-neutral-current interactions are studied model-independently using the effective Lagrangian consisting of several SU(3)xSU(2)xU(1) invariant dimension-6 operators. After the electroweak symmetry breaking, these operators are recombined to form four kinds of independent terms whose coefficients are complex in general. The Lagrangian could therefore include up to eight independent coupling parameters. Through searches for experimentally allowed regions of these parameters, it is found that some correlations exist among the signs and sizes of those couplings.

   hep-phEPL(2020)·2 citations
7. 07*

   An Update of the ABMP16 PDF Fit

   S. Alekhin🇩🇪 · J. Bluemlein🇩🇪 · S. Moch🇩🇪

   We present an updated version of the ABMP16 nucleon PDFs, which is tuned by using recent precise data on $W$- and $Z/{\gamma }^{\ast }$-production at the LHC and the final HERA data on DIS $c$- and $b$-quark production and by imposing a stringent $Q^2$-cut on the inclusive DIS data in order to avoid the impact of higher twist terms at small $x$ at HERA. The new $W$- and $Z$-boson production data, in particular the updated version of the ATLAS data at the c.m.s. energy 7 TeV, are well accommodated into the present fit. The strange sea distribution obtained is consistent with the average of the up and down quark ones at small $x$. However, it is still suppressed with respect to the non-strange one by a factor of $\sim 0.5$ at moderate $x$. The small-$x$ gluon distribution is enhanced as compared to the previous ABMP16 fit, in line with updated data on the DIS $c$-quark production. Finally, a good description of the non-resonant ${\gamma }^{\ast }/Z$-production data, which are included into the ABM analysis for the first time, is achieved provided the photon-initiated lepton pair production is taken into account.

   hep-phhep-ex9 citations
8. 08*

   Equivalence of light-front quantization and instant-time quantization

   Philip D. Mannheim🇺🇸

   Commutation or anticommutation relations quantized at equal instant time and commutation or anticommutation relations quantized at equal light-front time not only cannot be transformed into each other, they take completely different forms. While they would thus appear to describe different theories, we show that this is not in fact the case. By looking not at equal times but at unequal times, we show that unequal instant-time commutation or anticommutation relations are completely equivalent to unequal light-front time commutation or anticommutation relations. Light-front quantization and instant-time quantization are thus the same, with it being only the restriction to equal times that makes them look different. However for fermions there is a caveat, as the light-front anticommutation relations involve projection operators acting on the fermion fields. Nonetheless, not only can one still derive fermion unequal light-front time anticommutators starting from unequal instant-time ones, one can even derive unequal instant-time fermion anticommutators starting from unequal light-front time anticommutators even though the fermion projection operators that are relevant in the light-front case are not invertible. To establish the equivalence for gauge fields we present a quantization procedure that does not involve zero-mode singularities that are commonly encountered in light-front gauge field studies. We also study time-ordered products of fields, and again show the equivalence despite the fact that there are additional terms in the fermion light-front case. We establish our results first for free theories, and then to all orders in interacting theories though comparison of the instant-time and light-front Lehmann representations. Finally, we compare instant-time Hamiltonians and light-front Hamiltonians, and show that in the instant-time rest frame they give identical results.

   hep-phhep-thPRD(2020)·10 citations
9. 09*

   Relativistic effect of $J/\psi$ hadroproduction in large $p_T$ region

   Rong Li🇨🇳 · An-Ping Chen🇨🇳 · Jing-Kai Huang🇨🇳 · Yan-Qing Ma🇨🇳

   By combining NRQCD factorization and collinear factorization, we compute a series of relativistic corrections for $J/\psi$ hadroproduction to all orders in $v^2$ at large $p_T$ limit. The $v^2$ expansion converges well for all channels. We find that the ratio of relativistic correction term to the corresponding leading term is independent of kinematic variables for any channel, which generalizes the proportional relations found in previous works to all orders.

   hep-phJHEP(2019)·2 citations
10. 10*

    A bottom-up approach to fermion mass hierarchy: a case with vector-like fermions

    Yoshiharu Kawamura🇯🇵

    We propose a bottom-up approach that a structure of a high-energy physics is explored by accumulating existence proofs and/or no-go theorems in the standard model or its extension. As an illustration, we study fermion mass hierarchies based on an extension of the standard model with vector-like fermions. It is shown that a magnitude of elements of Yukawa coupling matrices can become $O(1)$ and a Yukawa coupling unification can be realized in a theory beyond the extended model, if vector-like fermions mix with three families. In this case, small Yukawa couplings in the standard model can be highly sensitive to a small variation of matrix elements, and it seems that the mass hierarchy occurs as a result of a fine tuning.

    hep-phPTEP(2020)·3 citations
11. 11*

    Hidden Monopole Dark Matter via Axion Portal and its Implications for Direct Detection Searches, Beam-Dump Experiments, and the $H_0$ Tension

    Ryuji Daido🇯🇵 · Shu-Yu Ho🇯🇵 · Fuminobu Takahashi🇯🇵

    Hidden monopole is a plausible dark matter candidate due to its stability, but its direct experimental search is extremely difficult due to feeble interactions with the standard model particles in the minimal form. Then, we introduce an axion, $a$, connecting the hidden monopole and the standard model particles and examine the current limits and future prospects of direct dark matter searches and beam-dump experiments. We find two parameter regions around $m_a=\mathcal{O}(10)$ MeV, $f_a=\mathcal{O}(10^5)$ GeV and $m_a=\mathcal{O}(100)$ MeV, $f_a=\mathcal{O}(10^4)$ GeV where monopole dark matter and the axion are respectively within the reach of the future experiments such as PICO-500 and SHiP. We also note that the hidden photons mainly produced by the axion decay contribute to dark radiation with $\Delta N_{\mathrm{eff}}\simeq 0.6$ which can relax the $H_0$ tension.

    hep-phastro-ph.COhep-thJHEP(2020)·23 citations
12. 12*

    Double parton interaction: the values of ${\sigma }_{\mathrm{eff}}$

    E. Gotsman (Tel Aviv U.)🇮🇱 · E. Levin (Tel Aviv U./UTFSM)🇮🇱

    In this letter we show that the two parton showers mechanism for $J/\Psi$ production, that has been discussed in Ref.[28], leads to small values of ${\sigma }_{\mathrm{eff}}$ for the production of a pair of $J/\Psi$. We develop a simple two channel approach to estimate the values of ${\sigma }_{\mathrm{eff}}$, which produces values that are in accord with the experimental data.

    hep-phhep-exPLB(2020)·1 citation
13. 13*

    Dipole subtraction at next-to-leading order in nonrelativistic-QCD factorization

    Mathias Butenschoen🇩🇪 · Bernd A. Kniehl🇩🇪

    We describe an implementation of a subtraction scheme in the nonrelativistic-QCD treatment of heavy-quarkonium production at next-to-leading-order in the strong-coupling constant, covering $S$- and $P$-wave bound states. It is based on the dipole subtraction in the massless version by Catani and Seymour and its extension to massive quarks by Phaf and Weinzierl. Important additions include the treatment of heavy-quark bound states, in particular due to the more complicated infrared-divergence structure in the case of $P$-wave states.

    hep-phNPB(2020)·15 citations
14. 14*

    Circular polarization of cosmic photons due to their interactions with Sterile neutrino dark matter

    M. Haghighat🇮🇷 · S. Mahmoudi🇮🇷 · R.Mohammadi🇮🇷 · S. Tizchang🇮🇷 · S.S Xue🇮🇹

    In this paper, we explore the possibility of the polarization conversion of a wide energy range of cosmic photons to the circular polarization through their interactions with right handed Sterile neutrinos as a candidate for dark matter. By considering the Sterile neutrino in the seesaw mechanism framework and right-handed current model, we examine the Faraday conversion $\Delta {\varphi }_{\text{FC}}$ of gamma ray burst (GRB) photons at both the prompt and afterglow emission levels as well as the radio photons emitted from our galaxy and extra-galactic sources interacting with the Sterile neutrinos. Consequently, for the Sterile neutrino with mixing angle ${\theta }^2\lesssim 10^{-2}$ motivated by models with a hidden sector coupled to the sterile neutrino, the Faraday conversion can be estimated as $\Delta {\varphi }_{\text{FC}}\lesssim 10^{-3}-10^{-18}$ rad for GRB, $\Delta {\varphi }_{\text{FC}}\lesssim 10^{-6}-10^{-11}$ rad for radio emission source from our galaxy and $\Delta {\varphi }_{\text{FC}}\lesssim 10^{-6}-10^{-15}$ rad for extra-galactic sources. We also examine the V-mode power spectrum $C_{Vl}$ of the cosmic microwave background (CMB) at the last scattering surface. We show that the circular polarization power spectrum at the leading order is proportional to the linear polarization power spectrum $C_{pl}$ and the mixing angle where for ${\theta }^2\lesssim 10^{-2}$ leads to $C_{Vl}\lesssim 0.01$ Nano-Kelvin squared.

    hep-phPRD(2020)·14 citations
15. 15*

    Initial conditions for electron and photon structure and fragmentation functions

    Stefano Frixione🇮🇹

    In the computation of short-distance cross sections initiated by electrons and photons one can adopt the so-called structure-function approach, in which these particles play formally the same roles as hadrons do in QCD factorisation theorems, and must thus be associated with PDFs (equivalently known as structure functions in this context). At variance with their QCD counterparts, such PDFs are entirely calculable in QED. In this paper we present the results, at the next-to-leading order in the QED coupling constant $\alpha$, for the initial conditions of the unpolarised electron and photon PDFs, which are a necessary ingredient for their eventual collinear evolution at the next-to-leading logarithmic accuracy. We also compute the analogous final-state quantities, namely the initial conditions for fragmentation functions into electrons and photons.

    hep-phJHEP(2019)·73 citations
16. 16*

    Photon emission in strong fields beyond the locally-constant field approximation

    I. A. Aleksandrov🇷🇺 · G. Plunien🇩🇪 · V. M. Shabaev🇷🇺

    We investigate a fundamental nonlinear process of vacuum photon emission in the presence of strong electromagnetic fields going beyond the locally-constant field approximation (LCFA), i.e., providing the exact treatment of the spatiotemporal inhomogeneities of the external field. We examine a standing electromagnetic wave formed by high-intensity laser pulses and benchmark the approximate predictions against the results obtained by means of a precise approach evaluating both the tadpole (reducible) and vertex (irreducible) contributions. It is demonstrated that the previously used approximate methods may fail to properly describe the quantitative characteristics of each of the two terms. In the case of the tadpole contribution, the LCFA considerably underestimates the number of photons emitted for sufficiently high frequency of the external field. The vertex term predicts emission of a great number of soft photons whose spectrum is no longer isotropic in contrast to the LCFA results. A notable difference among the photon yields along different spatial directions, which is not captured by the LCFA, represents an important signature for experimental studies of the photon emission process. Since this feature takes place unless the Keldysh parameter is much larger than unity, it can also be used in indirect observation of the Schwinger mechanism.

    hep-phhep-thPRD(2019)·22 citations
17. 17*

    $J/\psi$ Production Dynamics: Event shape, Multiplicity and Rapidity dependence in Proton+Proton Collisions at LHC energies using PYTHIA8

    Anisa Khatun🇮🇳 · Dhananjaya Thakur🇮🇳 · Suman Deb🇮🇳 · Raghunath Sahoo🇮🇳

    High-multiplicity pp collisions at the Large Hadron Collider (LHC) energies have created special importance in view of the Underlying Event (UE) observables. The recent results of LHC, such as long range angular correlation, flow-like patterns, strangeness enhancement etc. in high multiplicity events are not yet completely understood. In the same direction, the understanding of multiplicity dependence of J/$\psi$ production is highly necessary. Transverse spherocity, which is an event shape variable, helps to investigate the particle production by isolating the hard and the soft components. In the present study, we have investigated the multiplicity dependence of J/$\psi$ production at mid-rapidity and forward rapidity through the transverse spherocity analysis and tried to understand the role of jets by separating the isotropic and jetty events from the minimum bias collisions. We have analyzed the J/$\psi$ production at the mid-rapidity and forward rapidities via dielectron and dimuon channels, respectively using 4C tuned PYTHIA8 event generator. The analysis has been performed in two different center-of-mass energies: $\sqrt{s}$ = 5.02 and 13 TeV, to see the energy dependence of jet contribution to the multiplicity dependence study of J/$\psi$ production. Furthermore, we have studied the production dynamics through the dependence of thermodynamic parameters on event multiplicity and transverse spherocity.

    hep-phhep-exnucl-exnucl-thJ.Phys.G(2020)·15 citations
18. 18*

    Constraints on axions from neutron star in HESS J1731-347

    Lev B. Leinson🇷🇺

    To constrain the allowed range for the axion decay constant $f_a$ or, equivalently, for the axion mass $m_a$, we consider the cooling of a neutron star with strong proton superfluidity and normal (non-superfluid) neutrons inside its core and without strong magnetic field, by analogy with the observed supernova remnant in HESS J1731-347. For this specific case, we demonstrate that after the thermal relaxation is over, the hydrostatic structure of the neutron star can be well described with the aid of solution of Einstein field equations, applied to a sphere of fluid in hydrostatic equilibrium, derived by Tolman. The internal temperature of the neutron star is calculated assuming that the cooling occurs dominantly due to production of neutrino pairs and axions in the nn-bremsstrahlung. To impose a constraint to the axion decay constant the fact is used that the currently observed neutron star surface temperature does not deviate from the neutrino cooling scenario. For the KSVZ-axion model we find that $f_a>1.9\times 10^8$ GeV, while for the DFSZ-axion model we obtain $f_a>4.7\times 10^9$ GeV.

    hep-phastro-ph.HEJCAP(2019)·21 citations
19. 19*

    Scattering of charged particles off monopole-antimonopole pairs

    Vicente Vento🇪🇸 · Marco Traini🇮🇹

    The Large Hadron Collider is reaching energies never achieved before allowing the search for exotic particles in the TeV mass range. In a continuing effort to find monopoles we discuss the effect of the magnetic dipole field created by a pair of monopole-anti-monopole or monopolium on the successive bunches of charged particles in the beam at LHC.

    hep-phEPJC(2020)·12 citations
20. 20*

    Connecting the Muon Anomalous Magnetic Moment and the Multi-lepton Anomalies at the LHC

    Danielle Sabatta🇿🇦 · Alan S. Cornell🇿🇦 · Ashok Goyal🇿🇦 · Mukesh Kumar🇿🇦 · Bruce Mellado🇿🇦 · Xifeng Ruan🇿🇦

    A number of predictions were made in von Buddenbrock et al (2016 Eur. Phys. J. C 76, 10, 580) pertaining to the anomalous production of multiple leptons at the Large Hadron Collider. Discrepancies in multi-lepton final states have now become statistically compelling with the available Run~2 data. These could be connected with a heavy boson, $H$, decaying predominantly into a SM Higgs boson, $h$, and a singlet scalar, $S$, where $m_H\approx 270$\,GeV and $m_S\approx 150$\,GeV. These can be embedded into a scenario where a Two Higgs Doublet is considered with an additional singlet scalar, 2HDM+S. The long-standing discrepancy in the muon anomalous magnetic moment, $\Delta a_{\mu }$, is interpreted in the context of the 2HDM+S type-II and type-X, along with additional fermionic degrees of freedom. The 2HDM+S model alone with the constraints from the LHC data does not seem to explain the $\Delta a_{\mu }$ anomaly. However, adding fermions with mass of order $\mathcal{O}(100)$\,GeV can explain the discrepancy for low enough values of fermion-scalar couplings.

    hep-phCPC(2020)·54 citations
21. 21*

    $Z_c(4430)$, $Z_c(4200)$, $Z_1(4050)$, and $Z_2(4250)$ as triangle singularities

    Satoshi X. Nakamura (University of Science and Technology of China)🇨🇳

    $Z_c(4430)$ discovered in ${\bar{B}}^0\to \psi (2S)K^{-}{\pi }^{+}$, $Z_c(4200)$ found in ${\bar{B}}^0\to J/\psi K^{-}{\pi }^{+}$, and $Z_1(4050)$ and $Z_2(4250)$ observed in ${\bar{B}}^0\to {\chi }_{c1}{K}^{-}{\pi }^{+}$ are candidates of charged charmonium-like states. All surviving theoretical models interpreted these candidates as four-quark states, until we recently identified a compelling alternative. We discuss that kinematical singularities in triangle loop diagrams induce a resonance-like behavior that can consistently explain the properties (such as spin-parity, mass, width, and Argand plot) of $Z_c(4430)$, $Z_c(4200)$, $Z_1(4050)$ and $Z_2(4250)$ from experiments. In terms of the triangle singularities, we can also naturally understand interesting experimental findings such as the appearance (absence) of $Z_c(4200)$($Z_c(4430)$)-like contribution in ${\Lambda }_b^0\to J/\psi p{\pi }^{-}$, and the highly asymmetric shape of the spectrum bump for $Z_1(4050)$; the other theoretical models have not successfully addressed these points. Although Pakhlov et al. proposed another triangle diagram to generate a $Z_c(4430)$-like bump, we argue that this scenario is very unlikely.

    hep-phhep-exnucl-thAIP Conf.Proc.(2020)·3 citations
22. 22*

    Probing top quark FCNC couplings in the triple-top signal at the high energy LHC and future circular collider

    Hamzeh Khanpour🇮🇷

    Our main aim in this paper is to present detailed studies to probe the top quark flavor changing neutral current (FCNC) interactions at $tqg$, $tq\gamma$, $tqH$ and $tqZ({\sigma }^{\mu \nu },{\gamma }_{\mu })$ vertices in the triple-top signal $pp\to t\bar{t}t(\bar{t}t\bar{t})$ at the high energy proposal of Large Hadron Collider (HE-LHC) and future circular hadron-hadron collider (FCC-hh). To this end, we investigate the production of three top quarks which arises from the FCNC couplings taken into account the fast simulation at $\sqrt{s}=27$ TeV of HE-LHC and 100 TeV of FCC-hh considering the integrated luminosities of 10, 15 and 20 ab${}^{-1}$. All the relevant backgrounds are considered in a cut based analysis to obtain the limits on the anomalous couplings and the corresponding branching ratios. The obtained exclusion limits on the coupling strengths and the branching ratios are summarized and compared in details with the results in the literature, namely the most recent direct LHC experimental limits and HL-LHC projections as well. We show that, for higher energy phase of LHC, a dedicated search for the top quark FCNC couplings can achieve much better sensitivities to the triple-top signal than other top quark production scenarios. We found that the limits for the branching ratios of $tqg$ and $tqH$ transitions could reach an impressive sensitivity and the obtained 95\% CL limits are at least three orders of magnitude better than the current LHC experimental results as well as the existing projections of HL-LHC.

    hep-phhep-exNPB(2020)·31 citations
23. 23*

    Collider Phenomenology of a Gluino Continuum

    Christina Gao🇺🇸 · Ali Shayegan Shirazi🇺🇸 · John Terning🇺🇸

    Continuum supersymmetry is a class of models in which the supersymmetric partners together with part of the standard model come from a conformal sector, broken in the IR near the TeV scale. Such models not only open new doors for addressing the problems of the standard model, but also have unique signatures at hadron colliders, which might explain why we have not yet seen any superpartners at the LHC. Here we use gauge-gravity duality to model the conformal sector, generate collider simulations, and finally analyze continuum gluino signatures at the LHC. Due to the increase in the number of jets produced the bounds are weaker than for the minimal supersymmetric standard model with the same gluino mass threshold.

    hep-phJHEP(2020)·8 citations
24. 24*

    $A_4$ lepton flavor model and modulus stabilization from $S_4$ modular symmetry

    Tatsuo Kobayashi🇯🇵 · Yusuke Shimizu🇯🇵 · Kenta Takagi🇯🇵 · Morimitsu Tanimoto🇯🇵 · Takuya H. Tatsuishi🇯🇵

    We study the modulus stabilization in an $A_4$ model whose $A_4$ flavor symmetry is originated from the $S_4$ modular symmetry. We can stabilize the modulus so that the $A_4$ invariant superpotential leads to the realistic lepton masses and mixing angles. We also discuss the phenomenological aspect of the present model as a consequence of the modulus stabilization.

    hep-phPRD(2019)·162 citations
25. 25*

    Bottomonia production and polarization in the NRQCD with $k_T$-factorization. I: ${\rm Y}(3S)$ and ${\chi }_b(3P)$ mesons

    N.A. Abdulov🇷🇺 · A.V. Lipatov🇷🇺

    The ${\rm Y}(3S)$ production and polarization at high energies is studied in the framework of $k_T$-factorization approach. Our consideration is based on the non-relativistic QCD formalism for bound states formation and off-shell production amplitudes for hard partonic subprocesses. The transverse momentum dependent (TMD, or unintegrated) gluon densities in a proton were derived from the Ciafaloni-Catani-Fiorani-Marchesini (CCFM) evolution equation as well as from the Kimber-Martin-Ryskin (KMR) prescription. Treating the non-perturbative color octet transitions in terms of the multipole radiation theory and taking into account feed-down contributions from radiative ${\chi }_b(3P)$ decays, we extract the corresponding non-perturbative matrix elements for ${\rm Y}(3S)$ and ${\chi }_b(3P)$ mesons from a combined fit to ${\rm Y}(3S)$ transverse momenta distributions measured by the CMS and ATLAS Collaborations at the~LHC energies $\sqrt{s}=7$ and $13$~TeV and central rapidities. Then we apply the extracted values to describe the CDF and LHCb data on ${\rm Y}(3S)$ production and to investigate the polarization parameters ${\lambda }_{\theta }$, ${\lambda }_{\varphi }$ and ${\lambda }_{\theta \varphi }$, %and $\tilde{\lambda }$, which determine the ${\rm Y}(3S)$ spin density matrix. Our predictions have a good agreement with the currently available data within the theoretical and experimental uncertainties.

    hep-phEPJC(2019)·11 citations
26. 26*

    Finite Size Scaling in Time Evolution During the Colorless-QCD Confining Phase Transition

    Salah Cherif🇩🇿 · Madjid Lakhdar Hamou Ladrem🇸🇦 · Z.Z. Alfull🇸🇦 · M.A.A. Ahmed🇲🇾

    The time evolution of the expanding Colorless Partonic Matter, created in Ultra-Relativistic Heavy Ion Collisions and undergoing the confining phase transition towards a Hadronic Gas, is discussed in the context of a unified model combining our Colorless QCD-MIT Bag Model with the boost invariant Bjorken expansion. The Bjorken Equation in the case of a longitudinal expansion scenario of a non-ideal relativistic medium in finite volume is solved using certain initial conditions $({\tau }_i,T({\tau }_i))$ and their effect is studied in detail. The evolution of the temperature as a function of the proper time $T(\tau ,V)$ is then obtained at different volumes. Different times characterising different scales of the whole time evolution, like the time of the finite volume transition point ${\tau }_0(V)$, the hadronic time ${\tau }_H(V)$ at which the hadronization is completed, the lifetime of the Colorless Partonic Plasma $\Delta {\tau }_{CPP}(V)$ and the lifetime of the confining phase transition $\Delta {\tau }_{PT}(V)$ are calculated and their finite size scaling properties are studied in detail. New finite size scaling laws are derived. Also, the time evolution of some Thermal Response Functions as the order parameter $\mathcal{H}(\tau ,V)$, energy density $ϵ(\tau ,V)$, pressure $\mathcal{P}(\tau ,V)$ and the sound velocity ${\mathcal{C}}_s(\tau ,V)$ are investigated and studied in detail. We find that the time evolution of our system is really affected by the colorlessness requirement and the initial conditions of the partonic matter: the closer the volume is to the thermodynamic limit, the longer are the times and the lifetimes of the system. A detailed analysis of the temporal decreasing, in negative power, of the energy density $ϵ(\tau ,V)\propto {\tau }^{-\theta }$ in each of the three stages of the Bjorken expansion is carried out.

    hep-phnucl-th1 citation
27. 27*

    The energy and scale dependence of $\hat{q}$ and the JET puzzle

    Amit Kumar🇺🇸 · Abhijit Majumder🇺🇸 · Chun Shen🇺🇸

    We present an attempt to probe the underlying structure of the quark-gluon plasma (QGP) at high resolution, based on the extracted jet transport coefficient $\hat{q}$. We argue that the exchanged momentum $k$ between the hard parton and the medium varies over a range of scales, and for $k\ge$ 1 GeV, $\hat{q}$ can be expressed in terms of a parton distribution function (PDF). Because the mass of a QGP constituent is unknown, we define a scaling variable $x_N$ to represent the ratio of the parton momentum to the momentum of a self-contained section of the plasma which has a mass of 1 GeV. This scaling variable is used to parametrize the QGP-PDF. Calculations, based on this reconstructed $\hat{q}$ are compared to data sensitive to the hardcore of jets $i.e.,$ the single hadron suppression in terms of the nuclear modification factor $R_{AA}$ and the azimuthal anisotropy parameter $v_2$, as a function of transverse momentum $p_{\mathrm{T}}$, centrality and energy of the collision. It is demonstrated that the scale evolution of the QGP-PDF is responsible for the reduction in the normalization of $\hat{q}$ between fits to Relativistic Heavy-Ion Collider (RHIC) and Large Hadron Collider (LHC) data; a puzzle, first discovered by the JET collaboration.

    ↳ nucl-thhep-phnucl-exPRC(2020)·51 citations
28. 28*

    Generation of strong magnetic fields in old neutron stars accounting for continuous chiral magnetic effect

    Maxim Dvornikov (1)🇷🇺 · V.B. Semikoz (1)🇷🇺 · D.D. Sokoloff (2) ((1) IZMIRAN, (2) Moscow State University)🇷🇺

    We suggest a new mean field dynamo model in anomalous MagnetoHydroDynamics (AMHD) accounting for the mean spin (polarization) of the magnetized chiral (ultrarelativistic) plasma of a neutron star (NS). For simplicity we consider a non-superfluid NS with its rigid rotation neglecting also any matter turbulence (convection) within a star. On this way, we recover the Chiral Magnetic Effect (CME) as a possible source for the amplification of a seed, sufficiently strong magnetic field, $B\sim 10^{13}\text{G}$, up to values $B\gtrsim 10^{18}\text{G}$ in old NS's, having ages $t\gtrsim 10^6\text{yr}$. The important issue in AMHD model suggested is the continuous evolution of the chiral imbalance providing the CME for these ages, ${\partial }_t{\mu }_5(t)\ne 0$, in spite of the fast spin-flip in Coulomb collisions in the dense NS plasma that leads to vanishing ${\mu }_5\to 0$ at an earlier epoch in the corresponding protoneutron star. In contrast to the conventional mean-field dynamos, the dynamo drivers in the model are produced due to magnetic field generated at the previous stages of stellar evolution. It makes our model basically nonlinear.

    ↳ astro-ph.HEhep-ph0 citations
29. 29*

    Happy Birthday, Ultra-Cold Neutron!

    Hartmut Abele🇦🇹 · Tobias Jenke🇫🇷 · Hartmut Lemmel🇫🇷

    What is driving the accelerated expansion of the universe and do we have an alternative for Einstein's cosmological constant? What is dark matter made of? Do extra dimensions of space and time exist? Is there a preferred frame in the universe? To which extent is left-handedness a preferred symmetry in nature? What's the origin of the baryon asymmetry in the universe? These fundamental and open questions are addressed by precision experiments using ultra-cold neutrons. This year, we celebrate the 50th anniversary of their first production, followed by first pioneering experiments. Actually, ultra-cold neutrons were discovered twice in the same year, once in the eastern and once in the western world. For five decades now research projects with ultra-cold neutrons have contributed to the determination of the force constants of nature's fundamental interactions, and several technological breakthroughs in precision allow to address the open questions by putting them to experimental test. To mark the event and tribute to this fabulous object, we present a birthday song for ultra-cold neutrons with acoustic resonant transitions, which are based solely on properties of ultra-cold neutrons, the inertial and gravitational mass of the neutron, Planck's constant, and the local gravity. We make use of a musical intonation system that bears no relation to basic notation and basic musical theory as applied and used elsewhere but addresses two fundamental problems of music theory, the problem of reference for the concert pitch and the problem of intonation.

    ↳ nucl-exgr-qchep-phEPJ Web Conf.(2019)·1 citation
30. 30*

    A new Monte Carlo-based fitting method

    Paolo Pedroni (INFN, Pavia)🇮🇹 · Stefano Sconfietti (University and INFN, Pavia)🇮🇹

    We present a new fitting technique based on the parametric bootstrap method, which relies on the idea to produce artificial measurements using the estimated probability distribution of the experimental data. In order to investigate the main properties of this technique, we develop a toy model and we analyze several fitting conditions with a comparison of our results to the ones obtained using both the standard ${\chi }^2$ minimization procedure and a Bayesian approach. Furthermore, we investigate the effect of the data systematic uncertainties both on the probability distribution of the fit parameters and on the shape of the expected goodness-of-fit distribution. Our conclusion is that, when systematic uncertainties are included in the analysis, only the bootstrap procedure is able to provide reliable confidence intervals and p-values, thus improving the results given by the standard ${\chi }^2$ minimization approach. Our technique is then applied to an actual physics process, the real Compton scattering off the proton, thus confirming both the portability and the validity of the bootstrap-based fit method.

    ↳ physics.data-anhep-exhep-phnucl-ex+1J.Phys.G(2020)·12 citations
31. 31*

    Search for Dark Matter Annihilation to Neutrinos from the Sun

    Carlos A. Argüelles🇺🇸 · Ali Kheirandish🇺🇸 · Jeffrey Lazar🇺🇸 · Qinrui Liu (for the IceCube Collaboration)🇺🇸

    Weakly interacting massive particles (WIMPs) can be gravitationally captured by the Sun and trapped in its core. The annihilation of those WIMPs into Standard Model particles produces a spectrum of neutrinos whose energy distribution is related to the dark matter mass. In this work, we present the theoretical framework for relating an observed neutrino flux to the WIMP-nucleon cross section and summarize a previous solar WIMP search carried out by IceCube. We then outline an ongoing updated solar WIMP search, focusing on improvements over the previous search.

    ↳ astro-ph.HEhep-phPoS(2021)·5 citations
32. 32*

    A proposal for exploring quantum theory in curved spacetime in lab

    S. Ganesh🇮🇳

    Gravity curves spacetime. In regions where the de Broglie wavelength is very small compared to the curvature of spacetime, the wave equations in flat spacetime can be generalized to curved spacetime. The validity of the formulation when the de Broglie wavelength becomes comparable to the curvature is an open question. To test these formulations experimentally, huge energy of the order of the Planck mass would be required. Euclideanized spacetime is used to model thermal systems. In this work, an equivalence between spatial variation of temperature in thermal baths and curvature of Euclideanized spacetime is propounded. The variation in temperature is recast as a variation in the metric. The Dirac equation is then solved in this curved Euclideanized spacetime. The curvature in Euclideanized spacetime can be obtained in Chromodynamic or Electromagnetic scale energies. If this equivalence is correct, it could provide a platform to experimentally explore quantum mechanics in curved spacetime.

    ↳ hep-thgr-qchep-ph0 citations
33. 33*

    A CMB Search for the Neutrino Mass Mechanism and its Relation to the $H_0$ Tension

    Miguel Escudero🇬🇧 · Samuel J. Witte🇪🇸

    The majoron, a pseudo-Goldstone boson arising from the spontaneous breaking of global lepton number, is a generic feature of many models intended to explain the origin of the small neutrino masses. In this work, we investigate potential imprints in the Cosmic Microwave Background (CMB) arising from massive majorons, should they thermalize with neutrinos after Big Bang Nucleosynthesis via inverse neutrino decays. We show that Planck2018 measurements of the CMB are currently sensitive to neutrino-majoron couplings as small as $\lambda \sim 10^{-13}$, which if interpreted in the context of the type-I seesaw mechanism correspond to a lepton number symmetry breaking scale $v_L\sim \mathcal{O}(100)\mathrm{GeV}$. Additionally, we identify parameter space for which the majoron-neutrino interactions, collectively with an extra contribution to the effective number of relativistic species $N_{\mathrm{eff}}$, can ameliorate the outstanding $H_0$ tension.

    ↳ astro-ph.COhep-exhep-phEPJC(2020)·222 citations
34. 34*

    Clustering of primordial black holes formed in a matter-dominated epoch

    Takahiko Matsubara🇯🇵 · Takahiro Terada🇯🇵 · Kazunori Kohri🇯🇵 · Shuichiro Yokoyama🇯🇵

    In the presence of the local-type primordial non-Gaussianity, it is known that the clustering of primordial black holes (PBHs) emerges even on super-horizon scales at the formation time. This effect has been investigated in the high-peak limit of the PBH formation in the radiation-dominated epoch in the literature. There is another possibility that the PBH formation takes place in the early matter-dominated epoch. In this scenario, the high-peak limit is not applicable because even initially small perturbations grow and can become a PBH. We first derive a general formula to estimate the clustering of PBHs with primordial non-Gaussianity without assuming the high-peak limit, and then apply this formula to a model of PBH formation in a matter-dominated epoch. Clustering is less significant in the case of the PBH formation in the matter-dominated epoch than that in the radiation-dominated epoch. Nevertheless, it is much larger than the Poisson shot noise in many cases. Relations to the constraints of the isocurvature perturbations by the cosmic microwave background radiation are quantitatively discussed.

    ↳ astro-ph.COgr-qchep-phPRD(2019)·34 citations
35. 35*

    The QCD Trace Anomaly at Strong Coupling from M-Theory

    Aalok Misra🇮🇳 · Charles Gale🇨🇦

    In this short note we address the issue of obtaining the temperature dependence of the QCD conformal anomaly from a top-down holographic dual consistent with very recent lattice results for both, T<Tc and T>Tc. As the holographic dual, we use the M-theory uplift of the SYZ type IIA mirror obtained in arXiv:1306.4339 at finite gauge/string coupling (as part of the 'MQGP' limit) of the type IIB holographic dual of large-N thermal QCD of arXiv:0902.1540. We also show that after a tuning of the (small) Ouyang embedding parameter and radius of a blown-up S^2 when expressed in terms of the horizon radius, a QCD deconfinement temperature Tc = 150 MeV from a Hawking-Page phase transition at vanishing baryon chemical potential, consistent with lattice QCD in the heavy-quark limit, can be obtained.

    ↳ hep-thhep-phnucl-thEPJC(2020)·20 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.