Tue·May 21, 2019Tuesday·May 21, 2019

1. 01*

   Event shape and Multiplicity dependence of Freeze-out Scenario and System Thermodynamics in Proton+Proton Collisions at $\sqrt{s}$ = 13 TeV using PYTHIA8

   Sushanta Tripathy🇮🇳 · Ashish Bisht🇮🇳 · Raghunath Sahoo🇮🇳 · Arvind Khuntia🇵🇱 · Malavika Panikkassery Salvan🇮🇳

   Recent observations of QGP-like conditions in high-multiplicity pp collisions from ALICE experiment at the LHC warrants an introspection whether to use pp collisions as a baseline measurement to characterize heavy-ion collisions for possible formation of a Quark-Gluon Plasma. A double differential study of the particle spectra and thermodynamics of the produced system as a function of charged-particle multiplicity and transverse spherocity in pp collisions would shed light into the underlying event dynamics. Transverse spherocity, one of the event shape observables, allows to separate the events in terms of jetty and isotropic events. We analyse the identified particle transverse momentum ($p_{\mathrm{T}}$) spectra as a function of charged-particle multiplicity and transverse spherocity using Tsallis non-extensive statistics and Boltzmann-Gibbs Blastwave (BGBW) model in pp collisions at $\sqrt{s}$ = 13 TeV using PYTHIA8 event generator. The extracted parameters such as temperature ($T$), radial flow ($\beta$) and non-extensive parameter ($q$) are shown as a function of charged-particle multiplicity for different spherocity classes. We observe that the isotropic events approach to thermal equilibrium while the jetty ones remain far from equilibrium. We argue that, while studying the QGP-like conditions in small systems, one should separate the isotropic events from the spherocity-integrated events, as the production dynamics are different.

   hep-phhep-exnucl-exnucl-thAdv.High Energy Phys.(2021)·28 citations
2. 02*

   BEST potential in testing the eV-scale sterile neutrino explanation of reactor antineutrino anomalies

   Vladislav Barinov🇷🇺 · Vladimir Gavrin🇷🇺 · Valery Gorbachev🇷🇺 · Dmitry Gorbunov🇷🇺 · Tatiana Ibragimova🇷🇺

   Baksan Experiment on Sterile Neutrino (BEST) is presently at the stage of production of the artificial neutrino source Cr-51, the gallium exposure will start in July and proceed for three months. While aiming specifically at investigating the Gallium neutrino anomaly (SAGE and GALLEX experiments), BEST can do more and it is tempting to estimate its ability in testing sterile neutrino explanation of antineutrino (reactor) anomalies. We observe a moderate sensitivity to the region in model parameter space (sterile neutrino mass and mixing with active electron neutrino) outlined by the old reactor antineutrino anomaly and the best fit of DANSS experiment, while the Neutrino-4 favorite region falls right in the BEST ballpark. In particular, by analyzing SAGE+GALLEX and Neutrino-4 ${\chi }^2$ distributions we find that Neutrino-4 results are fully consistent with the Gallium anomaly, the significance of the combined anomaly almost reaches 4$\sigma$ level. If the BEST confirms the Neutrino-4 results, the joint analysis will indicate more than 5$\sigma$ evidence for the sterile neutrino of eV-scale mass.

   hep-phastro-ph.COhep-exPRD(2019)·11 citations
3. 03*

   TASI Lectures on Future Colliders

   Michelangelo Mangano🇨🇭

   These lectures review the main motivations for future high-energy colliders, focusing on the understanding of electroweak symmetry breaking and on the search for physics beyond the Standard Model. The open questions and the challenges are common to all future projects; for concreteness, I will use studies of the potential of ${\mathrm{e}}^{+}{\mathrm{e}}^{-}$ and pp circular colliders to provide examples of the anticipated physics reach.

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

   Neutrinoless double beta decay in effective field theory

   W. Dekens🇺🇸

   We discuss the contributions of lepton-number-violating sources to neutrinoless double beta decay ($0\nu \beta \beta$). Assuming that these sources arise at scales well above the electroweak scale, they can be described within an effective field theory. Here, we outline the steps required to express the $0\nu \beta \beta$ half-life in terms of the effective interactions, focusing on the dimension-five operator that induces a Majorana mass for the neutrinos. This process involves the evolution of the operators down to scales of a few GeV where they can be matched onto Chiral Perturbation Theory. The resulting Chiral Lagrangian can then used be to derive the lepton-number violating potential, which, in combination with many-body methods, gives the $0\nu \beta \beta$ half-life. We will show that consistent renormalization requires the inclusion of a new contact interaction at leading order in this potential. We also briefly comment on the constraints that can be set on the operators appearing beyond dimension five.

   hep-ph0 citations
5. 05*

   Double-heavy axial-vector tetraquark $T_{bc;\bar{u}\bar{d}}^0$

   S. S. Agaev🇦🇿 · K. Azizi🇹🇷 · H. Sundu🇹🇷

   The mass and coupling of the axial-vector tetraquark $T_{bc;\bar{u}\bar{d}}^0$ (in a short form $T_{bc}^0$) are calculated by means of the QCD two-point sum rule method. In computations we take into account contributions arising from various quark, gluon and mixed vacuum condensates up to dimension 10. The central value of the mass $m=(7105\pm 155)\mathrm{MeV}$ lies below the thresholds for the strong and electromagnetic decays of $T_{bc}^0$ state, and hence it transforms to conventional mesons only through the weak decays. In the case of $m=7260\mathrm{MeV}$ the tetraquark $T_{bc}^0$ becomes the strong- and electromagnetic-interaction unstable particle. In the first case, we find the full width and mean lifetime of $T_{bc}^0$ using its dominant semileptonic decays $T_{bc}^0\to T_{cc;\bar{u}\bar{d}}^{+}l{\overline{\nu }}_l$ ($l=e,\mu ,\tau$), where the final-state tetraquark is a scalar state. We compute also partial widths of the nonleptonic weak decays $T_{bc}^0\to T_{cc;\bar{u}\bar{d}}^{+}{\pi }^{-}(K^{-},D^{-},D_s^{-})$, and take into account their effects on the full width of $T_{bc}^0$. In the context of the second scenario we calculate partial widths of $S$-wave strong decays $T_{bc}^0\to B^{\ast -}{D}^{+}$ and $T_{bc}^0\to {\overline{B}}^{\ast 0}{D}^0$, and using these channels evaluate the full width of $T_{bc}^0$. Predictions for ${\Gamma }_{\mathrm{full}}=(3.98\pm 0.51)\times 10^{-10}\mathrm{MeV}$ and mean lifetime $\tau =1.65_{-0.18}^{+0.25}\mathrm{ps}$ of $T_{bc}^0$ obtained in the context of the first option, as well as the full width ${\Gamma }_{\mathrm{full}}=(63.5\pm 8.9)\mathrm{MeV}$ extracted in the second scenario may be useful for experimental and theoretical exploration of double-heavy exotic mesons.

   hep-phhep-exhep-latNPB(2020)·23 citations
6. 06*

   Flavor signatures of complex anomalous $tcZ$ couplings

   Suman Kumbhakar🇮🇳 · Jyoti Saini🇮🇳

   In this work we study the effects of anomalous $tcZ$ couplings. Such couplings would potentially affect several neutral current decays of $K$ and $B$ mesons via $Z$-penguin diagrams. Using constraints from relevant observables in $K$ and $B$ sectors, we find that the 2$\sigma$ upper bound on the branching ratio of $\mathcal{B}(t\to cZ)$ is $1.47\times 10^{-5}$ for real coupling and $1.91\times 10^{-4}$ for complex coupling. The current experimental upper bound from ATLAS and CMS collaborations on the branching ratio of $t\to cZ$ are $2.4\times 10^{-4}$ and $4.9\times 10^{-4}$ at $95\%$ C.L., respectively. Hence the possibility of observation of $t\to cZ$ decay at the level of $10^{-4}$ would imply the anomalous couplings to be complex. Such complex couplings should also show up its presence in other related decays. We find that an order of magnitude enhancement is possible in the branching ratio of $K_L\to {\pi }^0\nu \bar{\nu }$. Further, the complex $tcZ$ coupling can also provide large enhancements in many $CP$ violating angular observables in $B\to K^{\ast }{\mu }^{+}{\mu }^{-}$ decay.

   hep-phEur.Phys.J.Plus(2020)·6 citations
7. 07*

   Mass shifts of ${}^3{P}_J$ heavy quarkonia due to the effect of two-gluon annihilation

   Hui-Yun Cao🇨🇳 · Hai-Qing Zhou🇨🇳

   In this work, we calculate the nonrelativistic asymptotic behavior of the amplitudes of $q\overline{q}\to 2g\to q\overline{q}$ in the leading order of ${\alpha }_s$ (LO-${\alpha }_s$) with $q\overline{q}$ in the ${}^3{P}_J$ channels. In the practical calculation we take the momenta of quarks and antiquarks on-shell and expand the amplitudes on the three-momentum of the quarks and antiquarks to order 6 and get three nonzero terms. The imaginary parts of the first term and the second term are the old. The real parts of the results have IR divergence. When applying the results to the heavy quarkonia, the corresponding amplitude of $q\overline{q}\to 1g\to q\overline{q}$ with $q\overline{q}$ in the color octet ${}^3{S}_1$ channel is considered to absorb the IR divergence in a unitary way in the leading order of $v$ (LO-$v$). The finial results can be used to estimate the mass shifts of the ${}^3{P}_J$ heavy quarkonia due to the effect of two-gluon annihilation. The numerical estimation shows that the contributions to the mass shifts of ${\chi }_{c0,c1,c2}$ are about $1.23\sim 1.58$ MeV, $1.57\sim 1.86$ MeV and $5.92\sim 5.45$ MeV when taking ${\alpha }_s\approx 0.25\sim 0.35$.

   hep-phnucl-thPRD(2019)·1 citation
8. 08*

   Radiative transitions and magnetic moments of the charmed and bottom vector mesons in chiral perturbation theory

   Bo Wang🇨🇳 · Bin Yang🇨🇳 · Lu Meng🇨🇳 · Shi-Lin Zhu🇨🇳

   In this work, we systematically study the radiative decays and magnetic moments of the charmed and bottom vector mesons with chiral perturbation theory up to one-loop level. We present the results in SU(2) and SU(3) cases with the mass splitting in loop diagrams kept and unkept, respectively. The obtained decay rates for $D^{\ast }$ and $B^{\ast }$ mesons in SU(3) case with the mass splitting kept are: ${\Gamma }_{{\bar{D}}^{\ast 0}\to {\bar{D}}^0\gamma }=16.2_{-6.0}^{+6.5}$ keV, ${\Gamma }_{D^{\ast -}\to D^{-}\gamma }=0.73_{-0.3}^{+0.7}$ keV, ${\Gamma }_{D_s^{\ast -}\to D_s^{-}\gamma }=0.32_{-0.3}^{+0.3}$ keV, and ${\Gamma }_{B^{\ast +}\to B^{+}\gamma }=0.58_{-0.2}^{+0.2}$ keV, ${\Gamma }_{B^{\ast 0}\to B^0\gamma }=0.23_{-0.06}^{+0.06}$ keV, ${\Gamma }_{B_s^{\ast 0}\to B_s^0\gamma }=0.04_{-0.03}^{+0.03}$ keV. The decay width for $D^{\ast -}\to D^{-}\gamma$ is consistent with the experimental measurement. As a byproduct, the full widths of ${\bar{D}}^{\ast 0}$ and $D_s^{\ast -}$ are ${\Gamma }_{\mathrm{tot}}({\bar{D}}^{\ast 0})\simeq 77.7_{-20.5}^{+26.7}\mathrm{keV}$ and ${\Gamma }_{\mathrm{tot}}(D_s^{\ast -})\simeq 0.62_{-0.50}^{+0.45}\mathrm{keV}$, respectively. We also calculate the magnetic moments of the heavy vector mesons. The analytical chiral expressions derived in our work shall be helpful for the extrapolations of lattice QCD simulations in the coming future.

   hep-phPRD(2019)·29 citations
9. 09*

   Time-Delayed Electrons from Higgs Decays to Right-Handed Neutrinos

   John D. Mason🇺🇸

   We consider the physics reach at the high luminosity LHC (HL-LHC) using the timing capability of a minimum ionizing particle (MIP) timing layer and the electromagnetic calorimeter in the CMS experiment for a simplified right-handed neutrino effective theory. In the simplified model, the lightest right-handed neutrinos are produced through higgs decay with mean decay lengths of order $\mathcal{O}(0.1\mathrm{m}-100\mathrm{m}$) and then subsequently decay into final states that include electrons. We consider the effect of several different kinematic cuts for a timing based analysis of this model. We demonstrate that if timing information can be successfully incorporated into the event trigger, it is possible to probe the higgs branching ratio to two right-handed neutrinos to the order $\mathcal{O}(10^{-5})$ for a range of different right-handed neutrino lifetimes.

   hep-phhep-exJHEP(2019)·18 citations
10. 10*

    Associated top-pair production with a heavy boson production through NLO+NNLL accuracy at the LHC

    Anna Kulesza🇩🇪 · Leszek Motyka🇵🇱 · Daniel Schwartländer🇩🇪 · Tomasz Stebel🇵🇱 · Vincent Theeuwes🇩🇪

    In this talk we present results of our recent calculations of cross sections and distributions for the associate production of top-antitop quark pairs with a heavy boson (Higgs, W, Z) at the LHC, obtained using threshold resummation in direct QCD, i.e. in the Mellin-space approach.

    hep-ph8 citations
11. 11*

    Exotic pentaquark states with the $qqQQ\bar{Q}$ configuration

    Hong-Tao An🇨🇳 · Qin-Song Zhou🇨🇳 · Zhan-Wei Liu🇨🇳 · Yan-Rui Liu🇨🇳 · Xiang Liu🇨🇳

    In the framework of the color-magnetic interaction model, we have systematically calculated the mass splittings for the S-wave triply heavy pentaquark states with the configuration $qqQQ\bar{Q}$ $(Q=c,b;q=u,d,s)$. Their masses are estimated and their stabilities are discussed according to possible rearrangement decay patterns. Our results indicate that there may exist several stable or narrow such states. We hope the present study can help experimentalists to search for exotic pentaquarks.

    hep-phPRD(2019)·17 citations
12. 12*

    An Algebraic Analysis of Neutrino Masses and Mixings and its Implications on $\mu$-$\tau$ Symmetric Mass Matrix

    Chandan Duarah🇮🇳

    We diagonalize Majorana neutrino mass matrix with the help of PMNS matrix and obtain analytical relations between the mass matrix elements and mixing parameters, viz., three mixing angles- ${\theta }_{12},{\theta }_{23},{\theta }_{13}$ and Dirac CP phase \delta. We analyse our results in a special $\mu$-$\tau$ symmetric mass matrix which corresponds to maximal atmospheric mixing (${\theta }_{23}=\pi /4$) and maximal CP violation ($\delta =-\pi /2$). The analysis shows that a deviation of ${\theta }_{23}$ from its maximal value can be correlated with the prediction of other two mixing angles.

    hep-ph1 citation
13. 13*

    System size and Multiplicity dependence of Chemical freeze-out parameters at the Large Hadron Collider Energies

    Rutuparna Rath🇮🇳 · Arvind Khuntia🇵🇱 · Raghunath Sahoo🇮🇳

    The collision system and multiplicity dependence of chemical freeze-out temperature ($T_{\mathrm{ch}}$) and strangeness saturation factor (${\gamma }_s$) are obtained by studying the particle ratios at the Large Hadron Collider (LHC) energies. Here, we consider the new results in pp at 13 TeV, p+Pb at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV, Xe+Xe at $\sqrt{s_{\mathrm{NN}}}$ = 5.44 TeV and Pb+Pb at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV along with the earlier results in pp at $\sqrt{s}$ = 7 TeV and Pb+Pb at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV. A statistical thermal model is used to extract the chemical freeze-out parameters in different multiplicity classes. To understand the particle production from small to large collision systems two ensembles namely, canonical and grand canonical have been considered in this study. A clear observation of multiplicity dependence of $T_{\mathrm{ch}}$ and ${\gamma }_s$ is observed. The values obtained in high-multiplicity pp collisions are found to be similar to the peripheral Pb+Pb collisions. A final state midrapidity charged particle multiplicity density of around 20-30 appears to be a threshold below which, the chemical freeze-out temperature is lower than the kinetic freeze-out temperature.

    hep-phhep-exnucl-exnucl-th5 citations
14. 14*

    An effective scanning method of the NMSSM parameter space

    C. Beskidt (1) · W. de Boer (1) · ((1) Karlsruhe Institute of Technology, Germany)

    The next-to-minimal supersymmetric standard model (NMSSM) naturally provides a 125 GeV Higgs boson without the need for large loop corrections from multi-TeV stop quarks. Furthermore, the NMSSM provides an electroweak scale dark matter candidate consistent with all experimental data, like relic density and non-observation of direct dark matter signals with the present experimental sensitivity. However, more free parameters are introduced in the NMSSM, which are strongly correlated. A simple parameter scan without knowing the correlation matrix is not efficient and can miss significant regions of the parameter space. We introduce a new technique to sample the NMSSM parameter space, which takes into account the correlations. For this we project the 7D NMSSM parameter space onto the 3D Higgs boson mass parameter space. The reduced dimensionality allows for a non-random sampling and therefore a complete coverage of the allowed NMSSM parameters. In addition, the parameter correlations and possible deviations of the signal strengths of the observed 125 Higgs boson from the SM values are easily predicted.

    hep-phPRD(2019)·7 citations
15. 15*

    Search for opposite sign muon-tau pair and a b-jet at LHC in the context of flavor anomalies

    Debajyoti Choudhury🇮🇳 · Nilanjana Kumar🇮🇳 · Anirban Kundu🇮🇳

    Extant anomalies in several semileptonic $B$-meson decays argue for physics beyond the Standard Model. Measurements of both neutral-current decays (such as $R_K$, $R_{K^{\ast }}$ and $B_s\to \varphi \mu \mu$) as well as charged-current ones- $R(D)$ and $R(D^{\ast })$ -provide strong hints for the violation of lepton flavor universality. Recent studies have shown that a class of effective field theory (EFT) models may explain such anomalies in terms of only a few parameters which can be determined phenomenologically. In this literature, we examine such resolutions in the context of the requisite $(\bar{s}$ $b$)($\bar{\tau }\tau )$ operator, and look for its signals at the 13 TeV LHC, with a final state of one $b$-jet, and an oppositely charged $\mu$-$\tau$ pair, with the muon coming from the decay of one of the $\tau$ leptons. We obtain discovery and exclusion limits on the model parameters as a function of luminosity at the 13 TeV LHC.

    hep-phPRD(2019)·7 citations
16. 16*

    Numerical calculation of 5-loop QED contributions to the electron anomalous magnetic moment

    Sergey Volkov🇷🇺

    Preliminary numerical results of calculating the 5-loop QED contributions to the electron (and muon) anomalous magnetic moment are presented. The results include the total contribution of the 5-loop Feynman diagrams without lepton loops and the contributions of nine gauge-invariant classes that form that set. A discrepancy with known results is revealed. The contributions of the gauge-invariant classes are presented for the first time. The method of the computation is briefly described (with the corresponding references). The calculation is based on the following elements: 1) a subtraction procedure for removing infrared (IR) and ultraviolet (UV) divergences point by point in Feynman parametric representation before integration; 2) a nonadaptive Monte Carlo integration method that is founded on probability density functions (PDF) that are constructed for each Feynman diagram individually using its combinatorial structure; 3) a GPU-based numerical integration with the help of the supercomputer "Govorun" (JINR, Dubna, Russia).

    hep-phJ.Phys.Conf.Ser.(2020)·1 citation
17. 17*

    FiniteFlow: multivariate functional reconstruction using finite fields and dataflow graphs

    Tiziano Peraro🇨🇭

    Complex algebraic calculations can be performed by reconstructing analytic results from numerical evaluations over finite fields. We describe FiniteFlow, a framework for defining and executing numerical algorithms over finite fields and reconstructing multivariate rational functions. The framework employs computational graphs, known as dataflow graphs, to combine basic building blocks into complex algorithms. This allows to easily implement a wide range of methods over finite fields in high-level languages and computer algebra systems, without being concerned with the low-level details of the numerical implementation. This approach sidesteps the appearance of large intermediate expressions and can be massively parallelized. We present applications to the calculation of multi-loop scattering amplitudes, including the reduction via integration-by-parts identities to master integrals or special functions, the computation of differential equations for Feynman integrals, multi-loop integrand reduction, the decomposition of amplitudes into form factors, and the derivation of integrable symbols from a known alphabet. We also release a proof-of-concept C++ implementation of this framework, with a high-level interface in Mathematica.

    hep-phcs.SChep-thJHEP(2019)·356 citations
18. 18*

    Constraining Stealth SUSY with illuminated fat jets at the LHC

    Marvin Flores🇿🇦 · Deepak Kar🇿🇦 · Jong Soo Kim🇿🇦

    We investigate the discovery potential of a Stealth SUSY scenario involving squark decays by reconstructing the lightest neutralino decay products using a large-radius jet containing a high transverse momentum photon. Requirements on the event topology, such as photon and large-radius jet multiplicity result in less background than signal. We also estimated the sensitivity of our analysis and found that it has a better exclusion potential compared to the strongest existing search for the specific benchmark points considered here.

    hep-phPLB(2020)·2 citations
19. 19*

    The feasibility study of the long-baseline neutrino oscillation experiment at the SUNLAB laboratory in Poland

    Malgorzata Haranczyk🇵🇱

    The feasibility study of an underground laboratory in the Polkowice -Sieroszowice mine in Poland (SUNLAB) as a host of a far detector in a long-baseline neutrino oscillation experiment was performed. The SUNLAB location was previously studied under the LAGUNA FP7 project as a location for the underground multipurpose laboratory. The complementary study of the long-baseline neutrino experiment presented in this paper was performed as a continuation of this idea. A neutrino beam produced at CERN and a far LAr-TPC detector hosted in the SUNLAB laboratory were simulated. The sensitivity of such an experiment for the determination of the CP symmetry violation in the neutrino sector was calculated. The experiment at SUNLAB equipped with the 100 kton LAr TPC detector after 10 years of data taking can give the coverage of {\delta}CP parameter space of 58% (60%) for the normal (inverted) neutrino mass hierarchy at 3{\sigma} level in both cases reaches 5{\sigma} level in case of the maximal violation.

    hep-phphysics.ins-detActa Phys.Polon.B(2019)·0 citations
20. 20*

    Framework for a novel mixed analytical/numerical approach for the computation of two-loop $N$-point Feynman diagrams

    J. Ph. Guillet (1)🇫🇷 · E. Pilon (1)🇫🇷 · Y. Shimizu (2)🇯🇵 · M. S. Zidi (3) ((1) LAPTH, France (2) KEK, Japan (3) LPTh, Algérie)🇩🇿

    A framework to represent and compute two-loop $N$-point Feynman diagrams as double-integrals is discussed. The integrands are 'generalised one-loop type" multi-point functions multiplied by simple weighting factors. The final integrations over these two variables are to be performed numerically, whereas the ingredients involved in the integrands, in particular the "generalised one-loop type" functions, are computed analytically. The idea is illustrated on a few examples of scalar three- and four-point functions.

    hep-phPTEP(2020)·6 citations
21. 21*

    The transverse-momentum subtraction method at N${}^3$LO applied to Higgs boson production at the LHC

    Leandro Cieri🇮🇹

    We consider the extension of the transverse-momentum ($q_T$) subtraction method at next-to-next-to-next-to-leading order (N${}^3$LO) in perturbative QCD. While all the $q_T$-subtraction ingredients at $q_T\ne 0$ are known in analytical form, the third-order collinear functions and helicity-flip functions, which contribute only at $q_T=0$, are approximated using a prescription which uses the known result for the total Higgs boson cross section at this order. As a first application of the third-order $q_T$-subtraction method, we present the N${}^3$LO rapidity distribution of the Higgs boson at the LHC.

    hep-ph1 citation
22. 22*

    In-medium effect on the thermodynamics and transport coefficients in van der Waals hadron resonance gas

    He-Xia Zhang🇨🇳 · Jin-Wen Kang🇨🇳 · Ben-Wei Zhang🇨🇳

    An extension of the van der Waals hadron resonance gas (VDWHRG) model which includes in-medium thermal modification of hadron masses, the TVDWHRG model, is considered in this paper. Based on the 2+1 flavor Polyakov Linear Sigma Model(PLSM) and the scaling mass rule for hadrons we obtain the temperature behavior of all hadron masses for different fixed baryon chemical potentials ${\mu }_B$. We calculate various thermodynamic observables at ${\mu }_B=0$ GeV in TVDWHRG model. An improved agreement with the lattice data by TVDWHRG model in the crossover region ($T\sim 0.16-0.19$ GeV) is observed as compared to those by VDWHRG and Ideal HRG (IHRG) models. We further discuss the effects of in-medium modification of hadron masses and VDW interactions on the transport coefficients such as shear viscosity ($\eta$), scaled thermal ($\lambda /T^2$) and electrical (${\sigma }_{el}/T$ conductivities in IHRG model at different ${\mu }_B$, by utilizing quasi-particle kinetic theory with relaxation time approximation.

    hep-phnucl-thPRD(2020)·7 citations
23. 23*

    Electrical conductivity of hot Abelian plasma with scalar charge carriers

    O.O. Sobol🇨🇭

    We study the electrical conductivity of hot Abelian plasma containing scalar charge carriers in the leading logarithmic order in coupling constant $\alpha$ using the Boltzmann kinetic equation. The leading contribution to the collision integral is due to the Møller and Bhabha scattering of scalar particles with a singular cross section in the region of small momentum transfer. Regularizing this singularity by taking into account the hard thermal loop corrections to the propagators of intermediate particles, we derive the second order differential equation which determines the kinetic function. We solve this equation numerically and also use a variational approach in order to find a simple analytical formula for the conductivity. It has the standard parametric dependence on the coupling constant $\sigma \approx 2.38T/(\alpha \log {\alpha }^{-1})$ with the prefactor taking a somewhat lower value compared to the fermionic case. Finally, we consider the general case of hot Abelian plasma with an arbitrary number of scalar and fermionic particle species and derive the simple analytical formula for its conductivity.

    hep-phhep-thPRD(2019)·3 citations
24. 24*

    The $V_{cb}$ puzzle: an update

    Paolo Gambino🇮🇹 · Martin Jung🇮🇹 · Stefan Schacht🇺🇸

    We discuss the impact of the recent untagged analysis of $B^0\to D^{\ast }l{\bar{\nu }}_l$ decays by the Belle Collaboration on the extraction of the CKM element $|V_{cb}|$ and provide updated SM predictions for the $b\to c\tau \nu$ observables $R(D^{\ast })$, $P_{\tau }$, and $F_L^{D^{\ast }}$. The value of $|V_{cb}|$ that we find is about $2\sigma$ from the one from inclusive semileptonic $B$ decays, and is very sensitive to the slope of the form factor at zero recoil which should soon become available from lattice calculations.

    hep-phhep-exPLB(2019)·177 citations
25. 25*

    Addendum to "Impact of polarization observables and $B_c\to \tau \nu$ on new physics explanations of the $b\to c\tau \nu$ anomaly"

    Monika Blanke🇩🇪 · Andreas Crivellin🇨🇭 · Teppei Kitahara🇮🇱 · Marta Moscati🇩🇪 · Ulrich Nierste🇩🇪 · Ivan Nišandžić🇩🇪

    In this addendum to arXiv:1811.09603 we update our results including the recent measurement of $\mathcal{R}(D)$ and $\mathcal{R}(D^{\ast })$ by the Belle collaboration: $\mathcal{R}(D{)}_{\mathrm{Belle}}=0.307\pm 0.037\pm 0.016$ and $\mathcal{R}(D^{\ast }{)}_{\mathrm{Belle}}=0.283\pm 0.018\pm 0.014$, resulting in the new HFLAV fit result $\mathcal{R}(D)=0.340\pm 0.027\pm 0.013$, $\mathcal{R}(D^{\ast })=0.295\pm 0.011\pm 0.008$, exhibiting a $3.1\sigma$ tension with the Standard Model. We present the new fit results and update all figures, including the relevant new collider constraints. The updated prediction for $\mathcal{R}({\Lambda }_c)$ from our sum rule reads $\mathcal{R}({\Lambda }_c)={\mathcal{R}}_{\mathrm{SM}}({\Lambda }_c)\left(1.15\pm 0.04\right)=0.38\pm 0.01\pm 0.01$. We also comment on theoretical predictions for the fragmentation function $f_c$ of $b\to B_c$ and their implication on the constraint from $B_{u/c}\to \tau \nu$ data.

    hep-phhep-exPRD(2019)·154 citations
26. 26*

    Correlating Tauonic B Decays to the Neutron EDM via a Scalar Leptoquark

    Andreas Crivellin🇨🇭 · Francesco Saturnino🇨🇭

    In this article we investigate the correlations between tauonic $B$ meson decays (e.g. $B\to \tau \nu$, $B\to D^{(\ast )}\tau \nu$, $B\to \pi \tau \nu$) and electric dipole moments (EDMs), in particular the one of the neutron, in the context of the $S_1$ scalar leptoquark (LQ). This LQ naturally arises in the R-parity violating MSSM as the right-handed down-squark. We perform the matching of this model on the effective field theory taking into account the leading renormalization group effect for the relevant observables. We find that one can explain the hints for new physics in $b\to c\tau \nu$ transitions without violating bounds from other observables. Even more interesting, it can also give sizable effects in $B\to \tau \nu$, to be tested at BELLE II, which are correlated to (chromo) electric dipole operators receiving $m_{\tau }/m_u$ enhanced contributions. Therefore, given a deviation from the Standard Model (SM) expectations in $B\to \tau \nu$, this model predicts a sizable neutron EDM. In fact, even if new physics has CP conserving real couplings, the CKM matrix induces a complex phase and already a 10\% change of the $B\to \tau \nu$ branching ratio (with respect to the SM) will lead to an effect observable with the n2EDM experiment at PSI.

    hep-phhep-exnucl-exPRD(2019)·41 citations
27. 27*

    An Informational Approach to Cosmological Parameter Estimation

    Michelle Stephens🇺🇸 · Sara Vannah🇺🇸 · Marcelo Gleiser🇺🇸

    We introduce a new approach for cosmological parameter estimation based on the information-theoretical Jensen-Shannon divergence (${\mathcal{D}}_{\mathrm{JS}}$), calculating it for models in the restricted parameter space $\{H_0,w_0,w_a\}$, where $H_0$ is the value of the Hubble constant today, and $w_0$ and $w_a$ are dark energy parameters, with the other parameters held fixed at their best-fit values from the Planck 2018 data. As an application, we investigate the $H_0$ tension between the Planck temperature power spectrum data (TT) and the local astronomical data by comparing the $\Lambda$CDM model with the $w$CDM and the $w_0{w}_a$CDM dynamic dark energy models. We find agreement with other works using the standard Bayesian inference for parameter estimation; in addition, we show that while the ${\mathcal{D}}_{\mathrm{JS}}$ is equally minimized for both values of $H_0$ along the $(w_0,w_a)$ plane, the lines of degeneracy are different for each value of $H_0$. This allows for distinguishing between the two, once the value of either $w_0$ or $w_a$ is known.

    ↳ astro-ph.COhep-phPRD(2020)·7 citations
28. 28*

    On the convergence of nuclear effective field theory with perturbative pions

    David B. Kaplan🇺🇸

    The classic paper by Fleming, Mehen and Stewart cast doubts on the convergence of spin-triplet nucleon-nucleon partial wave scattering amplitudes when following the proposal of Kaplan, Savage and Wise to construct nuclear effective field theory around the unitary fermion limit with perturbative pion exchange. FMS identified the subclass of iterated one-pion exchange potential graphs as the cause of this poor convergence, which they showed persisted in the chiral limit. Theoretical tools are developed here to compute these Feynman graphs analytically to high order in all angular momentum channels simultaneously, examining the amplitudes computed to seven loops in the $L=J$ channels, and three loops in the coupled $L=J\pm 1$ channels. One finds that there is nothing pathological about the perturbative expansion of a $1/r^3$ potential in general, and that the expansion converges satisfactorily in all partial waves except those with the lowest angular momentum, particularly the ${}^3{P}_0$ and the coupled ${}^3{S}_1-{}^3{D}_1$ channels. The results corroborate work by Birse, which suggests possible avenues to explore for improving the range of validity of the EFT expansion.

    ↳ nucl-thhep-phPRC(2020)·41 citations
29. 29*

    Role of guiding center in Landau level system and mechanical and pseudo orbital angular momenta

    Yoshio Kitadono🇨🇳 · Masashi Wakamatsu🇯🇵 · Liping Zou🇨🇳 · Pengming Zhang🇨🇳

    There is an interesting but not so popular quantity called pseudo orbital angular momentum (OAM) in the Landau-level system, besides the well-known canonical and mechanical OAMs. The pseudo OAM can be regarded as a gauge-invariant extension of the canonical OAM, which is formally gauge invariant and reduces to the canonical OAM in a certain gauge. Since both of the pseudo OAM and the mechanical OAM are gauge invariant, it is impossible to judge which of those is superior to the other solely from the gauge principle. However, these two OAMs have totally different physical meanings. The mechanical OAM shows manifest observability and clear correspondence with the classical OAM of the cyclotron motion. On the other hand, we demonstrate that the standard canonical OAM as well as the pseudo OAM in the Landau problem are the concepts which crucially depend on the choice of the origin of the coordinate system. We try to reveal the relation between the pseudo OAM and the mechanical OAM as well as their observability by paying special attention to the role of guiding-center operator in the Landau problem.

    ↳ quant-phhep-phInt.J.Mod.Phys.A(2020)·12 citations
30. 30*

    Deep Inelastic Scattering on an Extremal RN-AdS Black Hole II: Holographic Fermi Surface

    Kiminad A. Mamo🇺🇸 · Ismail Zahed🇺🇸

    We consider deep inelastic scattering (DIS) on a dense nucleus described as an extremal RN-AdS black hole with holographic quantum fermions in the bulk. We evaluate the 1-loop fermion contribution to the R-current on the charged black hole, and map it on scattering off a Fermi surface of a dense and large nucleus with fixed atomic number. Near the black hole horizon, the geometry is that of AdS${}_2\times$R${}^3$ where the fermions develop an emergent Fermi surface with anomalous dimensions. DIS scattering off these fermions yields to anomalous partonic distributions mostly at large-x, as well as modified hard scattering rules. The pertinent R-ratio for the black hole is discussed. For comparison, the structure functions and the R-ratio in the probe or dilute limit with no back-reaction on the geometry, are also derived. We formulate a hybrid holographic model for DIS scattering on heavy and light nuclei, which compares favorably to the existing data for Pb, Au, Fe, C and He over a wide range of parton-x.

    ↳ hep-thhep-phnucl-thPRD(2020)·6 citations
31. 31*

    XYZ at Belle

    Jens Sören Lange (on behalf of the Belle Collaboration)🇩🇪

    Recent results of exotic states with heavy quarks, denoted as $XYZ$ states, are presented. The results include searches for the $Y$(4260) in $B$ meson decays, a spin partner of $Y$(4630), and the strange Pentaquark $P_s^{+}$. In addition, the measurements of the absolute branching fraction of $X$(3872) and search for double $Z_c$ production is discussed.

    ↳ hep-exhep-phEPJ Web Conf.(2019)·0 citations
32. 32*

    Dimensional Regularization and Dispersive Two-Loop Calculations

    A. Aleksejevs🇨🇦 · S. Barkanova🇨🇦

    The two-loop contributions are now often required by the precision experiments, yet are hard to express analytically while keeping precision. One way to approach this challenging task is via the dispersive approach, allowing to replace sub-loop diagram by effective propagator. This paper builds on our previous work, where we developed a general approach based on representation of many-point Passarino-Veltman functions in two-point function basis. In this work, we have extracted the UV-divergent poles of the Passarino-Veltman functions analytically and presented them as the dimensionally-regularized and multiply-subtracted dispersive sub-loop insertions, including self-energy, triangle, box and pentagon type.

    ↳ hep-thhep-ph2 citations
33. 33*

    Implications of a frame dependent dark energy for the spacetime metric, cosmography, and effective Hubble constant

    Stephen L. Adler🇺🇸

    In earlier papers we showed that a frame dependent effective action motivated by the postulates of three-space general coordinate invariance and Weyl scaling invariance exactly mimics a cosmological constant in Friedmann-Robertson-Walker (FRW) spacetimes, but alters the linearized equations governing scalar perturbations around a spatially flat FRW background metric. Here we analyze the implications of a frame dependent dark energy for the spacetime cosmological metric within both a perturbative and a non-perturbative framework. Both methods of calculation give a one-parameter family of cosmologies which are in close correspondence to one another, and which contain the standard FRW cosmology as a special case. We discuss the application of this family of cosmologies to the standard cosmological distance measures and to the effective Hubble parameter, with special attention to the current tension between determinations of the Hubble constant at late time, and the Hubble value obtained through the cosmic microwave background (CMB) angular fluctuation analysis.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2019)·20 citations
34. 34*

    Branes and the Swampland

    Hee-Cheol Kim🇰🇷 · Gary Shiu🇺🇸 · Cumrun Vafa🇺🇸

    Completeness of the spectrum of charged branes in a quantum theory of gravity naturally motivates the question of whether consistency of what lives on the branes can be used to explain some of the Swampland conditions. In this paper we focus on consistency of what lives on string probes, to show some of the theories with $\mathcal{N}=(1,0)$ supersymmetry in 10d and 6d, which are otherwise consistent looking, belong to the Swampland. Gravitational and gauge group anomaly inflow on these probes can be used to compute the gravitational central charges $(c_L,c_R)$ as well as the level of the group's current algebra $k_L$. The fact that the left-moving central charge on the string probes should be large enough to allow {\it unitary} representations of the current algebra with a given level, can be used to rule out some theories. This in particular explains why it has not been possible to construct the corresponding theories from string theory.

    ↳ hep-thhep-phPRD(2019)·133 citations
35. 35*

    Systematic investigation of the particle spectra in Heavy-ion collisions at the Large Hadron Collider

    Hua Zheng🇨🇳 · Xiangrong Zhu🇨🇳 · Lilin Zhu🇨🇳 · Aldo Bonasera🇺🇸

    We investigate the charged particle spectra produced in the heavy-ion collisions at nine centralities from different systems, i.e., Pb+Pb at $\sqrt{s_{NN}}=2.76$ TeV and 5.02 TeV as well as Xe+Xe at $\sqrt{s_{NN}}=5.44$ TeV, at Large Hadron Collider (LHC) using one empirical formula inspired by the solution of the Fokker-Planck equation, dubbed as the generalized Fokker-Planck solution (GFPS). Our results show that the GFPS can reproduce the experimental particle spectrum up to transverse momentum $p_T$ about 45 GeV/c with the maximum discrepancy 30\% covering 10 orders of magnitude. The discrepancy between the data and the results from the GFPS decreases to 15\% when the maximum of the charged particle transverse momentum is cut to 20 GeV/c. We confirmed that the Tsallis distribution derived from the non-extensive statistics, which can reproduce the particle spectra produced in small collision systems, such as p+p, up to few hundreds GeV/c, can only apply to systematically study the particle spectra up to 8 GeV/c in A+A collisions at LHC, as pointed out in the study of identified particle spectra in Pb+Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV. The possible explanation why GFPS functions well is also discussed.

    ↳ nucl-thhep-phMod.Phys.Lett.A(2020)·6 citations
36. 36*

    Quantum Fluctuations at the Planck Scale

    Fulvio Melia🇺🇸

    The recently measured cutoff, k_min=[4.34(+/-)0.50]/r_cmb (with r_cmb the comoving distance to the last scattering surface), in the fluctuation spectrum of the cosmic microwave background, appears to disfavor slow-roll inflation and the associated transition of modes across the horizon. We show in this Letter that k_min instead corresponds to the first mode emerging out of the Planck domain into the semi-classical universe. The required scalar-field potential is exponential, though not inflationary, and satisfies the zero active mass condition, rho_phi+3p_phi=0. Quite revealingly, the observed amplitude of the temperature anisotropies requires the quantum fluctuations in phi to have classicalized at ~3.5x10^15 GeV, consistent with the energy scale in grand unified theories. Such scalar-field potentials are often associated with Kaluza-Klein cosmologies, string theory and even supergravity.

    ↳ gr-qcastro-ph.COhep-phhep-thEPJC(2019)·10 citations
37. 37*

    Constraining the Parameters of High-Dimensional Models with Active Learning

    Sascha Caron🇳🇱 · Tom Heskes🇳🇱 · Sydney Otten🇳🇱 · Bob Stienen🇳🇱

    Constraining the parameters of physical models with $>5-10$ parameters is a widespread problem in fields like particle physics and astronomy. The generation of data to explore this parameter space often requires large amounts of computational resources. The commonly used solution of reducing the number of relevant physical parameters hampers the generality of the results. In this paper we show that this problem can be alleviated by the use of active learning. We illustrate this with examples from high energy physics, a field where simulations are often expensive and parameter spaces are high-dimensional. We show that the active learning techniques query-by-committee and query-by-dropout-committee allow for the identification of model points in interesting regions of high-dimensional parameter spaces (e.g. around decision boundaries). This makes it possible to constrain model parameters more efficiently than is currently done with the most common sampling algorithms and to train better performing machine learning models on the same amount of data. Code implementing the experiments in this paper can be found on GitHub.

    ↳ cs.LGastro-ph.IMhep-exhep-ph+1EPJC(2019)·39 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.