Tue·Sep 26, 2017Tuesday·September 26, 2017

1. 01*

   Bayesian analysis and naturalness of (Next-to-)Minimal Supersymmetric Models

   Peter Athron🇦🇺 · Csaba Balazs🇦🇺 · Benjamin Farmer🇸🇪 · Andrew Fowlie🇦🇺 · Dylan Harries🇦🇺 · Doyoun Kim🇰🇷

   The Higgs boson discovery stirred interest in next-to-minimal supersymmetric models, due to the apparent fine-tuning required to accommodate it in minimal theories. To assess their naturalness, we compare fine-tuning in a ${\mathbb{Z}}_3$ conserving semi-constrained Next-to-Minimal Supersymmetric Standard Model (NMSSM) to the constrained MSSM (CMSSM). We contrast popular fine-tuning measures with naturalness priors, which automatically appear in statistical measures of the plausibility that a given model reproduces the weak scale. Our comparison shows that naturalness priors provide valuable insight into the hierarchy problem and rigorously ground naturalness in Bayesian statistics. For the CMSSM and semi-constrained NMSSM we demonstrate qualitative agreement between naturalness priors and popular fine tuning measures. Thus, we give a clear plausibility argument that favours relatively light superpartners.

   hep-phJHEP(2017)·23 citations
2. 02*

   Competing Forces in 5-Dimensional Fermion Condensation

   Jongmin Yoon🇺🇸 · Michael E. Peskin🇺🇸

   We study fermion condensation in the Randall-Sundrum background as a setting for composite Higgs models. We formalize the computation of the Coleman-Weinberg potential and present a simple, general formula. Using this tool, we study the competition of fermion multiplets with different boundary conditions, to find conditions for creating a little hierarchy with the Higgs field expectation value much smaller than the intrinsic Randall-Sundrum mass scale.

   hep-phPRD(2017)·9 citations
3. 03*

   Thermal vorticity production in relativistic dissipative fluids

   Yang-guang Yang🇨🇳 · Shi Pu🇯🇵

   We have computed the circulation integrations of thermal vorticity with and without charged currents in dissipative fluids. We find that the relativistic Kelvin circulation theorem will be modified by the dissipative effects, therefore, the circulation integrations of thermal vorticity may not be conserved during the fluid evolution.

   hep-phnucl-thActa Phys.Polon.Supp.(2017)·2 citations
4. 04*

   Transport coefficients in Polyakov quark meson coupling model: a relaxation time approximation

   Aman Abhishek🇮🇳 · Hiranmaya Mishra🇮🇳 · Sabyasachi Ghosh🇮🇳

   We compute the transport coefficients, namely, the coefficients of shear and bulk viscosities as well as thermal conductivity for hot and dense matter. The calculations are performed within the Polyakov quark meson model. The estimation of the transport coefficients is made using the Boltzmann kinetic equation within the relaxation time approximation. The energy dependent relaxation time is estimated from meson meson scattering, quark meson scattering and quark quark scattering within the model. In our calculations, the shear viscosity to entropy ratio and the coefficient of thermal conductivity show a minimum at the critical temperature, while the ratio of bulk viscosity to entropy density exhibits a peak at this transition point.The effect of confinement modelled through a Polyakov loop potential plays an important role in the estimation of these dissipative coefficients both below and above the critical temperature.

   hep-phPRD(2018)·55 citations
5. 05*

   Heavy Quarkonium Hybrids

   Joan Soto🇪🇸

   We report on a recent investigation on heavy quarkonium hybrids that goes beyond the usual Born-Oppenheimer approximation by including not only the mixing between nearby hybrid states but also the mixing with quarkonium states. We use a systematic effective field theory framework based on NRQCD together with lattice QCD inputs. Short and long distance constraints from weak coupling pNRQCD and the QCD effective string theory are also employed. We calculate the quarkonium and hybrid spectrum for charmonium and bottomonium, and estimate a number of decay widths. Most of the isospin zero $XYZ$ resonances fit in our spectrum either as quarkonia or as hybrid states. The mixing of hybrid states with quarkonia produces enhanced spin symmetry violations, which are instrumental to understand certain decays. We also present new results on the hyperfine splittings.

   hep-phNucl.Part.Phys.Proc.(2018)·17 citations
6. 06*

   Reconsideration of the QCD corrections to the ${\eta }_c$ decays into light hadrons using the principle of maximum conformality

   Bo-Lun Du🇨🇳 · Xing-Gang Wu🇨🇳 · Jun Zeng🇨🇳 · Shi Bu🇨🇳 · Jian-Ming Shen🇨🇳

   In the paper, we analyze the ${\eta }_c$ decays into light hadrons at the next-to-leading order QCD corrections by applying the principle of maximum conformality (PMC). The relativistic correction at the $\mathcal{O}({\alpha }_s{v}^2)$-order level has been included in the discussion, which gives about $10\%$ contribution to the ratio $R$. The PMC, which satisfies the renormalization group invariance, is designed to obtain a scale-fixed and scheme-independent prediction at any fixed order. To avoid the confusion of treating $n_f$-terms, we transform the usual $\overline{\mathrm{MS}}$ pQCD series into the one under the minimal momentum space subtraction scheme. To compare with the prediction under conventional scale setting, $R_{\mathrm{Conv},\mathrm{mMOM}-\mathrm{r}}=\left(4.12_{-0.28}^{+0.30}\right)\times 10^3$, after applying the PMC, we obtain $R_{\mathrm{PMC},\mathrm{mMOM}-\mathrm{r}}=\left(6.09_{-0.55}^{+0.62}\right)\times 10^3$, where the errors are squared averages of the ones caused by $m_c$ and ${\Lambda }_{\mathrm{mMOM}}$. The PMC prediction agrees with the recent PDG value within errors, i.e. $R^{\exp }=\left(6.3\pm 0.5\right)\times 10^3$. Thus we think the mismatching of the prediction under conventional scale-setting with the data is due to improper choice of scale, which however can be solved by using the PMC.

   hep-phEPJC(2018)·3 citations
7. 07*

   Status of exclusion limits of the KK-parity non-conserving resonance production with updated 13 TeV LHC

   Avirup Shaw🇮🇳

   Unequal strengths of boundary localised terms lead to non-conservation of the Kaluza-Klein (KK) parity in the 4 + 1 Universal Extra Dimensional model. Consequently the first excited KK-partners of Standard Model particles are not stable by any symmetry. In this article using the latest 13 TeV Large Hadron Collider (LHC) results, we revisit the resonant production of first KK-excitations of the neutral gauge bosons ($G^1$, $B^1\text{and}{W}_3^1$) and their subsequent decay. {\it Specifically $G^1$ (first KK-excitation of gluon) decays to $t\bar{t}$ pair and $B^1/W_3^1$ (first KK-excitation of electroweak gauge bosons) decay to ${\ell }^{+}{\ell }^{-}(\ell \equiv e,\mu )$ pair}. We find the exclusion limits of model parameters obtained at 95\% C.L. from the non-observation of these channels have been shifted towards the lower side of the parameter space compared to our previous analysis at 8 TeV.

   hep-phActa Phys.Polon.B(2018)·9 citations
8. 08*

   Lepton flavor violating Higgs decay at $e^{+}{e}^{-}$ colliders

   Indrani Chakraborty🇮🇳 · Subhadeep Mondal🇮🇳 · Biswarup Mukhopadhyaya🇮🇳

   We estimate the smallest branching ratio for the Higgs decay channel $h\to \mu \tau$, which can be probed at an $e^{+}{e}^{-}$ collider and compare it with the projected reach at the high-luminosity run of the LHC. Using a model-independent approach, Higgs production is considered in two separate cases. In the first case, $hWW$ and $hZZ$ couplings are allowed to be scaled by a factor allowed by the latest experimental limits on $hWW$ and $hZZ$ couplings. In the second case, we have introduced higher-dimensional effective operators for these interaction vertices. Keeping BR($h\to \mu \tau$) as a purely phenomenological quantity, we find that this branching ratio can be probed down to $\approx 2.69\times 10^{-3}$ and $\approx 5.83\times 10^{-4}$ respectively, at the 250 GeV and 1000 GeV run of an $e^{+}{e}^{-}$ collider.

   hep-phPRD(2017)·10 citations
9. 09*

   Regge phenomenology of photoproduction of ${\pi }^{-}{\Delta }^{++}$ and scaling with saturation of trajectory

   Byung-Geel Yu🇰🇷 · Kook-Jin Kong🇰🇷

   In this work we investigate the reaction $\gamma p\to {\pi }^{-}{\Delta }^{++}$ in the Reggeized model for $\pi (138)+\rho (775)+a_2(1320)$ exchanges in the $t$-channel. For a convergence of the reaction cross section at high energies the minimal forms of proton and ${\Delta }^{++}$ exchanges are introduced in the direct and crossed channels for gauge invariance of $\pi$ Regge-pole exchange. The role of spin-2 tensor meson $a_2$ is found to be crucial to agree with existing data at high energies. Electromagnetic multipoles of ${\Delta }^{++}$ baryon are analyzed in the $\Delta$ resonance region. Based on the constituents counting rule the scaled differential cross section at $E_{\gamma }=4$ GeV is reproduced with the Regge trajectory saturated at large momentum transfer $-t$.

   hep-phnucl-thPhys.Part.Nucl.Lett.(2018)·2 citations
10. 10*

    Estimates of W-exchange contributions to ${\Xi }_{cc}$ decays

    Neelesh Sharma🇮🇳 · Rohit Dhir🇮🇳

    Encouraged by recent discovery of ${\Xi }_{cc}^{++}$ baryon, we investigate two body non-leptonic weak decays of doubly charmed, ${\Xi }_{cc}$, baryons. We calculate the branching ratios for CKM-favored and suppressed modes in factorization and pole model approach. We give the first estimates of nonfactorizable W-exchange contributions using pole model. We find that W-exchange contributions to ${\Xi }_{cc}$ decays being sizable can not be ignored.

    hep-phPRD(2017)·54 citations
11. 11*

    Testing NSI suggested by the solar neutrino tension in T2HKK and DUNE

    Monojit Ghosh🇯🇵 · Osamu Yasuda🇯🇵

    It was shown that the tension between the mass-squared differences obtained from solar neutrinos and those acquired through KamLAND experiments may be solved by the introduction of a non-standard flavor-dependent interaction (NSI) in neutrino propagation. In this study, we discuss the possibility of testing such a hypothesis using the future long-baseline neutrino experiments T2HKK and DUNE. Assuming that the NSI does not exist, we provide the excluded region within the (${ϵ}_D$, ${ϵ}_N$) plane, where ${ϵ}_D$ and ${ϵ}_N$ are the parameters appearing in the solar neutrino analysis conducted with the NSI. We find that the best-fit value from the solar neutrino and KamLAND data (global analysis of a particular coupling to quarks) can be tested at more than 10$\sigma$ (3$\sigma$) by these two experiments for most of the parameter space.

    hep-phMod.Phys.Lett.A(2020)·15 citations
12. 12*

    Prediction of the $CP$ asymmetry $C_{00}$ in $B^0\to D^0\overline{D^0}$ decay

    Dibyakrupa Sahoo🇰🇷 · Hai-Yang Cheng🇹🇼 · Cheng-Wei Chiang🇹🇼 · C. S. Kim🇰🇷 · Rahul Sinha🇮🇳

    Of all $B\to D\overline{D}$ decays, the $B^0\to D^0\overline{D^0}$ decay has the smallest observed branching ratio as it takes place primarily via the suppressed $W$-exchange diagram. The $CP$ asymmetry for this mode is yet to be measured experimentally. By exploiting the relationship among the decay amplitudes of $B\to D\overline{D}$ decays (using isospin and topological amplitudes) we are able to relate the $CP$ asymmetries and branching ratios by a simple expression. This enables us to predict the $CP$ asymmetry $C_{00}$ in $B^0\to D^0\overline{D^0}$. While the predicted central values of $C_{00}$ are outside the physically allowed region, they are currently associated with large uncertainties owing to the large errors in the measurements of the $B^0\to D^0\overline{D^0}$ branching ratio ($B_{00}$), the other $CP$ asymmetries $C_{+-}$ (of $B^0\to D^{+}{D}^{-}$) and $A_{\text{CP}}$ (of $B^{+}\to D^{+}\overline{D^0}$). With a precise determination of $B_{00}$, $C_{+-}$ and $A_{\text{CP}}$, one can use our analytical result to predict $C_{00}$ with a reduced error and compare it with the experimental measurement when it becomes available. The correlation between $B_{00}$ and $C_{00}$ is an interesting aspect that can be probed in ongoing and future particle physics experiments such as LHCb and Belle II.

    hep-phJHEP(2017)·2 citations
13. 13*

    An update on nuclear PDFs at the LHeC

    Hannu Paukkunen (for the LHeC study group)🇫🇮

    The prospects for a measurement of nuclear parton distribution functions (PDFs) at the Large Hadron--Electron Collider are discussed in the light of recent progress made in the front of global analysis of nuclear PDFs.

    hep-phhep-exPoS(2018)·19 citations
14. 14*

    The Role of Different Schemes in the QCD Analysis and Determination of the Strong Coupling

    A. Vafaee🇮🇷 · A. N. Khorramian🇮🇷

    In this article, we present a Next-to-Leading Order (NLO) QCD analysis to study the role and influence of different schemes on simultaneous determination of the Parton Distribution Functions (PDFs) and strong coupling, ${\alpha }_s(M_Z^2)$. We perform our analysis based on three different data sets, HERA I and II combined data, H1-ZEUS charm combined data, and H1 and ZEUS beauty production cross sections data, in two different Thorne-Roberts (TR or RT) and Thorne-Roberts Optimal (RT OPT) schemes. We show in going from RT scheme to RT OPT scheme, in addition of reduction the uncertainty of some PDFs, specially for the gluon distribution, we get $\sim 0.4$~\% and $\sim 0.7$~\%~improvement in the fit quality and $\sim 0.9$~\% and $\sim 1.6$~\%~improvement for the strong coupling, ${\alpha }_s(M_Z^2)$, without and with heavy flavor contributions, respectively.

    hep-phNPB(2017)·17 citations
15. 15*

    The EPPS16 nuclear PDFs

    Kari J. Eskola🇫🇮 · Petja Paakkinen🇫🇮 · Hannu Paukkunen🇫🇮 · Carlos A. Salgado🇪🇸

    We report on EPPS16 - the first analysis of NLO nuclear PDFs where LHC p-Pb data (Z, W, dijets) have been directly used as a constraint. In comparison to our previous fit EPS09, also data from neutrino-nucleus deeply-inelastic scattering and pion-nucleus Drell-Yan process are now included. Much of the theory framework has also been updated from EPS09, including a consistent treatment of heavy quarks in deeply-inelastic scattering. However, the most notable change is that we no longer assume flavour-blind nuclear modifications for valence and sea quarks. This significantly reduces the theoretical bias. All the analysed data are well reproduced and the analysis thereby supports the validity of collinear factorization in high-energy collisions involving heavy nuclei. However, flavour by flavour, the uncertainties are still rather large.

    hep-phhep-exPoS(2018)·6 citations
16. 16*

    Features of W production in p-p, p-Pb and Pb-Pb collisions

    François Arleo🇫🇷 · Émilien Chapon🇨🇭 · Hannu Paukkunen🇫🇮

    We consider the production of inclusive W bosons in variety of high-energy hadronic collisions: p--p, p--$\overline{\mathrm{p}}$, p--Pb, and Pb--Pb. In particular, we focus on the resulting distributions of charged leptons from W decay that can be measured with relatively low backgrounds. The leading-order expressions within the collinearly factorized QCD indicate that the center-of-mass energy dependence at forward/backward rapidities should be well approximated by a simple power law. The scaling exponent is related to the small-$x$ behaviour of the quark distributions, which is largely driven by the parton evolution. An interesting consequence is the simple scaling law for the lepton charge asymmetry which relates measurements in different collision systems. The expectations are contrasted with the existing data and a very good overall agreement is found. Finally, we propose precision observables to be measured at the LHC.

    hep-phhep-exPoS(2018)·1 citation
17. 17*

    General structure of fermion two-point function and its spectral representation in a hot magnetised medium

    Aritra Das🇮🇳 · Aritra Bandyopadhyay🇮🇳 · Pradip K. Roy🇮🇳 · Munshi G. Mustafa🇮🇳

    We have systematically constructed the general structure of the fermion self-energy and the effective quark propagator in presence of a nontrivial background like hot magnetised medium. This is applicable to both QED and QCD. The hard thermal loop approximation has been used for the heat bath. We have also examined transformation properties of the effective fermion propagator under some of the discrete symmetries of the system. Using the effective fermion propagator we have analysed the fermion dispersion spectra in a hot magnetised medium along with the spinor for each fermion mode obtained by solving the modified Dirac equation. The fermion spectra is found to reflect the discrete symmetries of the two-point functions. We note that for a chirally symmetric theory the degenerate left and right handed chiral modes in vacuum or in a heat bath get separated and become asymmetric in presence of magnetic field without disturbing the chiral invariance. The obtained general structure of the two-point functions is verified by computing the three-point function, which agrees with the existing results in one-loop order. Finally, we have computed explicitly the spectral representation of the two-point functions which would be very important to study the spectral properties of the hot magnetised medium corresponding to QED and QCD with background magnetic field.

    hep-phhep-latnucl-thPRD(2018)·31 citations
18. 18*

    Standard convolution description of deuteron tensor spin structure

    W. Cosyn🇧🇪 · Yu-Bing Dong🇨🇳 · S. Kumano🇯🇵 · M. Sargsian🇺🇸

    Spin-1 hadrons have additional structure functions not present for spin 1/2 hadrons. These could probe novel aspects of hadron structure and QCD dynamics. For the deuteron, the tensor structure function $b_1$ inherently mixes quark and nuclear degrees of freedom. These proceedings discuss two standard convolution models applied to calculations of the deuteron $b_1$ structure functions. We find large differences with the existing HERMES data and other convolution model calculations. This leaves room for non-standard contributions to $b_1$ in the deuteron. We also discuss the influence of higher twist nuclear effects in the model calculations and data extraction at kinematics covered in HERMES and Jefferson Lab.

    hep-phnucl-thPoS(2018)·0 citations
19. 19*

    Impact of Charm H1-ZEUS Combined data and Determination of the Strong Coupling in Two Different Schemes

    A. Vafaee🇮🇷 · A. N. Khorramian🇮🇷

    We study the impact of recent measurements of charm cross section H1-ZEUS combined data on simultaneous determination of parton distribution functions (PDFs) and the strong coupling, ${\alpha }_s(M_Z^2)$, in two different schemes. We perform several fits based on Thorne-Roberts (RT) and Thorne-Roberts optimal (RTOPT) schemes at next-to-leading order (NLO). We show that adding charm cross section H1-ZEUS combined data reduces the uncertainty of the gluon distribution and improves the fit quality up to $\sim 0.4$~\% and $\sim 0.9$~\%~, without and with the charm contribution, from the RT scheme to the RTOPT scheme, respectively. We also emphasise the central role of the strong coupling, ${\alpha }_s(M_Z^2)$, in revealing the impact of charm flavour contribution, when it is considered as an extra free parameter. We show that in going from the RT scheme to the RT OPT scheme, we get $\sim 0.9$~\% and $\sim 2.0$~\%~improvement in the value of ${\alpha }_s(M_Z^2)$, without and with the charm flavour contribution respectively.

    hep-phCPC(2017)·2 citations
20. 20*

    Common Origin of Neutrino Mass and Dark Matter from Anomaly Cancellation Requirements of a $U(1{)}_{B-L}$ Model

    Dibyendu Nanda🇮🇳 · Debasish Borah🇮🇳

    We study a gauged $B-L$ extension of the standard model where the new fermions with fractional $B-L$ charges that play the role of keeping the model anomaly free can also explain the origin of neutrino mass at one loop level as well as dark matter. We discuss two different versions of the model to realise fermion and scalar dark matter, both of which guarantee the dark matter stability by a remnant discrete symmetry to which $U(1{)}_{B-L}$ gauge symmetry gets spontaneously broken down to. Apart from giving rise to the observed neutrino mass and dark matter abundance, the model also has tantalising signatures at variety of experiments operating at cosmic, intensity and energy frontiers, particularly direct and indirect detection experiments of dark matter, rare decay experiments looking for charged lepton flavour violation as well as collider experiments. The model also predicts vanishing lightest neutrino mass that can be tested at experiments sensitive to the absolute neutrino mass scale.

    hep-phastro-ph.COPRD(2017)·50 citations
21. 21*

    Five-loop renormalisation of QCD in covariant gauges

    K. G. Chetyrkin🇩🇪 · G. Falcioni🇳🇱 · F. Herzog🇳🇱 · J.A.M. Vermaseren🇳🇱

    We present the complete set of vertex, wave function and charge renormalisation constants in QCD in a general simple gauge group and with the complete dependence on the covariant gauge parameter $\xi$ in the minimal subtraction scheme of conventional dimensional regularisation. Our results confirm all already known results, which were obtained in the Feynman gauge, and allow the extraction of other useful gauges such as the Landau gauge. We use these results to extract the Landau gauge five-loop anomalous dimensions of the composite operator $A^2$ as well as the Landau gauge scheme independent gluon, ghost and fermion propagators at five loops.

    hep-phJHEP(2017)·189 citations
22. 22*

    Constraints on low energy QCD parameters from $\eta \to 3\pi$ and $\pi \pi$ scattering

    Marian Kolesar🇨🇿 · Jiri Novotny🇨🇿

    The $\eta \to 3\pi$ decays are a valuable source of information on low energy QCD. Yet they were not used for an extraction of the three flavor chiral symmetry breaking order parameters until now. We use a Bayesian approach in the framework of resummed chiral perturbation theory to obtain constraints on the quark condensate and pseudoscalar decay constant in the chiral limit. We compare our results with recent CHPT and lattice QCD fits and find some tension, as the $\eta \to 3\pi$ data seem to prefer a larger ratio of the chiral order parameters. The results also disfavor a very large value of the pseudoscalar decay constant in the chiral limit, which was found by some recent works. In addition, we present results of a combined analysis including $\eta \to 3\pi$ decays and $\pi \pi$ scattering and though the picture does not changed appreciably, we find some tension between the data we use. We also try to extract information on the mass difference of the light quarks, but the uncertainties prove to be large.

    hep-phEPJC(2018)·11 citations
23. 23*

    Analysis of the Bounds on Dark Matter Models from Monojet Searches at the LHC

    Swasti Belwal🇩🇪 · Manuel Drees🇩🇪 · Jong Soo Kim🇿🇦

    We analyse the constraints on models of WIMP Dark Matter that can be derived from upper bounds on the "monojet" cross section at the LHC. These constraints were originally interpreted in the context of an effective field theory (EFT) where the Standard Model is extended by a dimension--6 operator whose coefficient is $1/{\Lambda }^2$. We show that combining the 8 TeV data of the ATLAS and CMS collaborations improves the bounds only slightly. We then analyze this final state in the context of simplified models with $s-$channel mediator. We show that if the decay width of the mediator is small, these simplified models can be accurately modeled by the effective field theory only if the mediator mass is above 5 TeV. Finally, we point out that even if the EFT accurately describes the $\mathcal{O}({\Lambda }^{-2})$ contributions to the matrix element, for values of $\Lambda$ near the current bound it receives significant contributions of order ${\Lambda }^{-4}$, in the context of simplified models, these correspond to diagrams where two mediators are exchanged. This observation challenges the internal consistency of the EFT description since dimension$-8$ operators, which would also contribute to $\mathcal{O}({\Lambda }^{-4})$ to the matrix element, are not included.

    hep-phPRD(2018)·10 citations
24. 24*

    Resolving Dark Matter Subhalos With Future Sub-GeV Gamma-Ray Telescopes

    Ti-Lin Chou🇺🇸 · Dimitrios Tanoglidis🇺🇸 · Dan Hooper🇺🇸

    Annihilating dark matter particles in nearby subhalos could generate potentially observable fluxes of gamma rays, unaccompanied by emission at other wavelengths. Furthermore, this gamma-ray emission is expected to be spatially extended, providing us with a powerful way to discriminate dark matter subhalos from other astrophysical gamma-ray sources. Fermi has detected two dark matter subhalo candidates which exhibit a statistically significant degree of spatial extension (3FGL J2212.5+0703 and 3FGL J1924.8-1034). It has been argued that the most likely non-dark matter interpretation of these observations is that they are each in fact multiple nearby point sources, too close to one another on the sky to be individually resolved. In this study, we consider the ability of next generation gamma-ray telescopes to spatially resolve the gamma-ray emission from subhalo candidates, focusing on the proposed e-ASTROGAM mission. We find that such an instrument could significantly clarify the nature of Fermi's dark matter subhalo candidates, and provide an unprecedented level of sensitivity to the presence of annihilating dark matter in nearby subhalos.

    hep-phastro-ph.COastro-ph.GAastro-ph.HEPhys.Dark Univ.(2018)·11 citations
25. 25*

    Standard Model Theory

    Stefan Dittmaier🇩🇪

    The field of precision calculations for Standard Model processes at the LHC has experienced enormous progress in recent years. This talk highlights some examples from the physics of parton distribution functions, jets, electroweak gauge bosons and Higgs bosons.

    hep-ph2 citations
26. 26*

    Scalar Dark Matter in Leptophilic Two-Higgs-Doublet Model

    Priyotosh Bandyopadhyay🇮🇳 · Eung Jin Chun🇰🇷 · Rusa Mandal🇮🇳

    Two-Higgs-Doublet Model of Type-X in the large $\tan \beta$ limit becomes leptophilic to allow a light pseudo-scalar $A$ and thus provides an explanation of the muon $g-2$ anomaly. Introducing a singlet scalar dark matter $S$ in this context, one finds that two important dark matter properties, nucleonic scattering and self-annihilation, are featured separately by individual couplings of dark matter to the two Higgs doublets. While one of the two couplings is strongly constrained by direct detection experiments, the other remains free to be adjusted for the relic density mainly through the process $SS\to AA$. This leads to the $4\tau$ final states which can be probed by galactic gamma ray detections.

    hep-phhep-exPLB(2018)·18 citations
27. 27*

    Theoretical analysis of the $\gamma \gamma \to {\pi }^0\eta$ process

    Igor Danilkin🇩🇪 · Oleksandra Deineka🇩🇪 · Marc Vanderhaeghen🇩🇪

    We present a theoretical study of the $\gamma \gamma \to \pi \eta$ process from the threshold up to 1.4 GeV in the $\pi \eta$ invariant mass. For the s-wave $a_0(980)$ resonance state we adopt a dispersive formalism using a coupled-channel Omnès representation, while the d-wave $a_2(1320)$ state is described as a Breit-Wigner resonance. An analytic continuation to the $a_0(980)$ pole position allows us to extract its two-photon decay width as ${\Gamma }_{a_0\to \gamma \gamma }=0.27(4)$ keV.

    hep-phPRD(2017)·46 citations
28. 28*

    Dynamical vs geometric anisotropy in relativistic heavy-ion collisions: which one prevails?

    L.V. Bravina🇳🇴 · I.P. Lokhtin🇷🇺 · L.V. Malinina🇷🇺 · S.V. Petrushanko🇷🇺 · A.M. Snigirev🇷🇺 · E.E. Zabrodin🇳🇴

    We study the influence of geometric and dynamical anisotropies on the development of flow harmonics and, simultaneously, on the second- and third-order oscillations of femtoscopy radii. The analysis is done within the Monte Carlo event generator HYDJET++, which was extended to dynamical triangular deformations. It is shown that the merely geometric anisotropy provides the results which anticorrelate with the experimental observations of either $v_2$ (or $v_3$) or second-order (or third-order) oscillations of the femtoscopy radii. Decays of resonances significantly increase the emitting areas but do not change the phases of the radii oscillations. In contrast to the spatial deformations, the dynamical anisotropy alone provides the correct qualitative description of the flow and the femtoscopy observables simultaneously. However, one needs both types of the anisotropy to match quantitatively the experimental data.

    hep-phnucl-exnucl-thEPJA(2017)·14 citations
29. 29*

    NLO and off-shell effects in top quark mass determinations

    G.Heinrich🇩🇪 · A.Maier🇨🇭 · R.Nisius🇩🇪 · J.Schlenk🇬🇧 · M.Schulze🇩🇪 · L.Scyboz🇩🇪 · J.Winter🇺🇸

    We study the impact of different theoretical descriptions of top quark pair production on top quark mass measurements in the di-lepton channel. To this aim, the full NLO corrections to $pp\to W^{+}{W}^{-}b\bar{b}\to (e^{+}{\nu }_e)({\mu }^{-}{\bar{\nu }}_{\mu })b\bar{b}$ production are compared to calculations in the narrow width approximation, where the production of a top quark pair is calculated at NLO and combined with three different descriptions of the top quark decay: leading order, next-to-leading order and via a parton shower. The different theory predictions then enter the calibration of template fit functions, which are used for a fit to pseudo-data. The offsets in the top quark mass resulting from the fits based on the various theoretical descriptions are determined.

    hep-phJHEP(2018)·42 citations
30. 30*

    Trigonometric Parity for the Composite Higgs

    Csaba Csáki🇺🇸 · Teng Ma🇨🇳 · Jing Shu🇨🇳

    We identify trigonometric parity as the key ingredient behind models of neutral naturalness for the Higgs potential. We show that any symmetric coset space readily includes such a trigonometric parity, which is simply a combination of a $\pi /2$ rotation along a broken direction and a Higgs parity transformation. We explain how to extend the top sector such that this $Z_2$ remains intact while the rest of the shift symmetry is explicitly broken, resulting in the cancelation of the quadratic divergences in the Higgs potential. Assuming additional structure (for example partial compositeness with maximal symmetry) can render the Higgs potential completely finite and with minimal tuning. We apply our principles to construct the minimal model realizing trigonometric parity based on $SO(6)/SO(5)\simeq SU(4)/Sp(4)$, yielding the simplest model of neutral naturalness. An added advantage of this model is that a simple fermionic UV completion can be easily identified. We analyze the tuning of the Higgs potential and find that the top partners can be quite heavy while vector mesons need to be relatively light to obtain minimal tuning. Finally we briefly comment on some novel phenomenology, including a possible six top final state at the LHC appearing in this model.

    hep-phhep-thPRL(2018)·68 citations
31. 31*

    Dihadron fragmentation functions in the quark-jet model: Transversely polarized quarks

    Hrayr H. Matevosyan🇦🇺 · Aram Kotzinian🇦🇲 · Anthony W. Thomas🇦🇺

    Within the most recent extension of the quark-jet hadronization framework, we explore the transverse-polarization-dependent dihadron fragmentation functions (DiFFs) $H_1^{\sphericalangle }$ and $H_1^{\perp }$ of a quark into ${\pi }^{+}{\pi }^{-}$ pairs. Monte Carlo (MC) simulations are employed to model polarized quark hadronization and calculate the corresponding number densities. These, in turn, are used to extract the Fourier cosine moments of the DiFFs $H_1^{\sphericalangle }$ and $H_1^{\perp }$. A notable finding is that there are previously unnoticed apparent discrepancies between the definitions of the so-called interference DiFF (IFF) $H_1^{\sphericalangle }$, entering the cross sections for two-hadron semi-inclusive electroproduction, and those involved in the production of two pairs of hadrons from back-to-back jets in electron-positron annihilation. This manuscript completes the studies of all four leading twist DiFFs for unpolarized hadron pairs within the quark-jet framework, following our previous work on the helicity-dependent DiFF $G_1^{\perp }$.

    hep-phhep-exnucl-thPRD(2018)·23 citations
32. 32*

    New Physics effect on $B_c\to J/\psi \tau \bar{\nu }$ in relation to the $R_{D^{(\ast )}}$ anomaly

    Ryoutaro Watanabe🇨🇦

    We study possible new physics (NP) effects on $B_c\to J/\psi \tau \bar{\nu }$, which has been recently measured at LHCb as the ratio of $R_{J/\psi }=\mathcal{B}(B_c\to J/\psi \tau \bar{\nu })/\mathcal{B}(B_c\to J/\psi \mu \bar{\nu })$. Combining it with the long-standing $R_{D^{(\ast )}}$ measurements, in which the discrepancy with the prediction of the standard model is present, we find possible solutions to the anomaly by several NP types. Then, we see that adding the $R_{J/\psi }$ measurement does not improve NP fit to data, but the NP scenarios still give better ${\chi }^2$ than the SM. We also investigate indirect NP constraints from the lifetime of $B_c$ and NP predictions on the $\tau$ longitudinal polarization in $\bar{B}\to D^{\ast }\tau \bar{\nu }$.

    hep-phPLB(2018)·127 citations
33. 33*

    Optimizing Higgs factories by modifying the recoil mass

    Jiayin Gu🇨🇳 · Ying-Ying Li🇨🇳

    It is difficult to measure the $WW$-fusion Higgs production process ($e^{+}{e}^{-}\to \nu \bar{\nu }h$) at a lepton collider with a center of mass energy of 240-250 GeV due to its small rate and the large background from the Higgsstrahlung process with an invisible $Z$ ($e^{+}{e}^{-}\to hZ,Z\to \nu \bar{\nu }$). We construct a modified recoil mass variable, $m_{\mathrm{recoil}}^p$, defined using only the 3-momentum of the reconstructed Higgs particle, and show that it can better separate the $WW$-fusion and Higgsstrahlung events than the original recoil mass variable $m_{\mathrm{recoil}}$. Consequently, the $m_{\mathrm{recoil}}^p$ variable can be used to improve the overall precisions of the extracted Higgs couplings, in both the conventional framework and the effective-field-theory framework. We also explore the application of the $m_{\mathrm{recoil}}^p$ variable in the inclusive cross section measurements of the Higgsstrahlung process, while a quantitive analysis is left for future studies.

    hep-phhep-exCPC(2018)·2 citations
34. 34*

    XYZ-SU3 Breakings from Laplace Sum Rules at Higher Orders

    R. Albuquerque (FAT, UERJ-Rio de Janeiro)🇧🇷 · S. Narison (LUPM-Montpellier)🇫🇷 · D. Rabetiarivony🇲🇬 · G. Randriamanatrika (iHEPMAD, Antananarivo)🇲🇬

    We present new compact integrated expressions of SU3 breaking corrections to QCD spectral functions of heavy-light molecules and four-quark XYZ-like states at lowest order (LO) of perturbative (PT) QCD and up to d=8 condensates of the OPE. Including N2LO PT corrections in the chiral limit and NLO SU3 PT corrections, which we have estimated by assuming the factorization of the four-quark spectral functions, we improve previous LO results for the XYZ-like masses and decay constants from QCD spectral sum rules. Systematic errors are estimated from a geometric growth of the higher order PT corrections and from some partially known d=8 non-perturbative contributions. Our optimal results, based on stability criteria, are summarized in Tables 18 to 21 and compared with some LO results in Table 22. In most channels, the SU3 corrections on the meson masses are tiny: < 10% (resp. <3%) for the c (resp. b)-quark channel but can be large for the couplings (< 20%). Within the lowest dimension currents, most of the 0^{++} and 1^{++} states are below the physical thresholds while our predictions cannot discriminate a molecule from a four-quark state. A comparison with the masses of some experimental candidates indicates that the 0^{++} X(4500) might have a large D^*_{s0}D^*_{s0} molecule component while an interpretation of the 0^{++} candidates as four-quark ground states is not supported by our findings. The 1^{++} X(4147) and X(4273) are compatible with the D^*_{s}D_{s}, \bar D^*_{s0}D_{s1} molecules and/or with the axial-vector A_c four-quark ground state. Our results for the 0^{-\pm}, 1^{-\pm} and for different beauty states can be tested in the future data. Finally, we revisit our previous estimates [1] for the D^*_{0}D^*_{0} and D^*_{0}D_{1} and present new results for the D_1D_1.

    hep-phhep-exhep-latInt.J.Mod.Phys.A(2018)·29 citations
35. 35*

    Neutron stars: A novel equation of state with induced surface tension

    Violetta V. Sagun🇺🇦 · Ilidio Lopes🇵🇹

    A novel equation of state with the surface tension induced by particles' interactions was generalized to describe the properties of the neutron stars (NSs). In this equation the interaction between particles occurs via the hard core repulsion by taking into account the proper volumes of particles. Recently, this model was successfully applied to the description of the properties of nuclear and hadron matter created in collisions of nucleons. The new approach is free of causality problems and is fully thermodynamically consistent, which enables us to use it for the investigation of the strongly interacting matter phase-diagram properties in a wide range of temperatures and baryon densities, including NSs. Here, we have calculated the mass-radius relations for a compact star using the Tolmann-Oppenheimer-Volkov (TOV) equation for two sets of parameters that satisfy the existing constraints. Accordingly, we found parameter values that are in good agreement with the same ones obtained from the nuclear-nuclear collision data analysis. The astrophysical constraints suggest that the hard core radius of baryons can vary between 0.425 fm and 0.476 fm.

    ↳ astro-ph.HEhep-phApJ(2017)·9 citations
36. 36*

    The impact of ultra-light axion self-interactions on the large scale structure of the Universe

    Vincent Desjacques🇮🇱 · Alex Kehagias🇬🇷 · Antonio Riotto🇨🇭

    Ultra-light axions have sparked attention because their tiny mass $m\sim 10^{-22}$ eV, which leads to a Kiloparsec-scale de Broglie wavelength comparable to the size of dwarf galaxy, could alleviate the so-called small-scale crisis of massive cold dark matter (CDM) candidates.However, recent analyses of the Lyman-$\alpha$ forest power spectrum set a tight lower bound on their mass of $m\gtrsim 10^{-21}$ eV which makes them much less relevant from an astrophysical point of view. An important caveat to these numerical studies is that they do not take into account attractive self-interactions among ultra-light axions, which can counteract the quantum "pressure" induced by the strong delocalization of the particles. In this work, we show that even a tiny attractive interaction among ultra-light axions can have a significant impact on the stability of cosmic structures at low redshift. After a brief review of known results about solitons in the absence of gravity, we discuss the stability of filamentary and pancake-like solutions when quantum pressure, attractive interactions and gravity are present. The analysis based on one degree of freedom, namely the breathing mode, reveals that pancakes are stable, while filaments are unstable if the mass per unit length is larger than a critical value. However, we show that pancakes are unstable against transverse perturbations. We expect this to be true for halos and filaments as well. Instabilities driven by the breathing mode will not be seen in the low column density Lyman-$\alpha$ forest unless the axion decay constant is extremely small, $f\lesssim 10^{13}$ GeV. Notwithstanding, axion solitonic cores could leave a detectable signature in the Lyman-$\alpha$ forest if the normalization of the unknown axion core - filament mass relation is $\sim 100$ larger than it is for spherical halos.

    ↳ astro-ph.COhep-phhep-thPRD(2018)·103 citations
37. 37*

    An analytic relation between the fractional parameter in the Mittag-Leffler function and the chemical potential in the Bose-Einstein distribution through the analysis of the NASA COBE monopole data

    Minoru Biyajima🇯🇵 · Takuya Mizoguchi🇯🇵 · Naomichi Suzuki🇯🇵

    To extend the Bose-Einstein (BE) distribution to fractional order, we turn our attention to the differential equation, $df/dx=-f-f^2$. It is satisfied with the stationary solution, $f(x)=1/(e^{x+\mu }-1)$, of the Kompaneets equation, where $\mu$ is the constant chemical potential. Setting $R=1/f$, we obtain a linear differential equation for $R$. Then, the Caputo fractional derivative of order $p$ ($p>0$) is introduced in place of the derivative of $x$, and fractional BE distribution is obtained, where function ${\mathrm{e}}^x$ is replaced by the Mittag-Leffler (ML) function $E_p(x^p)$. Using the integral representation of the ML function, we obtain a new formula. Based on the analysis of the NASA COBE monopole data, an identity $p\simeq e^{-\mu }$ is found.

    ↳ cond-mat.stat-mechcond-mat.quant-gashep-phJ.Phys.Conf.Ser.(2017)·0 citations
38. 38*

    Classification of Standard-like Heterotic-String Vacua

    Alon E. Faraggi🇬🇧 · John Rizos🇬🇷 · Hasan Sonmez🇬🇧

    We extend the free fermionic classification methodology to the class of standard-like heterotic-string vacua, in which the $SO(10)$ GUT symmetry is broken at the string level to $SU(3)\times SU(2)\times U(1{)}^2$. The space of GGSO free phase configurations in this case is vastly enlarged compared to the corresponding $SO(6)\times SO(4)$ and $SU(5)\times U(1)$ vacua. Extracting substantial numbers of phenomenologically viable models therefore requires a modification of the classification methods. This is achieved by identifying conditions on the GGSO projection coefficients, which are satisfied at the $SO(10)$ level by random phase configurations, and that lead to three generation models with the $SO(10)$ symmetry broken to the $SU(3)\times SU(2)\times U(1{)}^2$ subgroup. Around each of these fertile $SO(10)$ configurations, we perform a complete classification of standard-like models, by adding the $SO(10)$ symmetry breaking basis vectors, and scanning all the associated GGSO phases. Following this methodology we are able to generate some $10^7$ three generation Standard-like Models. We present the results of the classification and one exemplary model with distinct phenomenological properties, compared to previous SLM constructions.

    ↳ hep-thhep-phNPB(2018)·58 citations
39. 39*

    An numerical approach for finite volume three-body interaction

    Peng Guo🇺🇸 · Vladimir Gasparian🇺🇸

    In present work, we study an numerical approach to one dimensional finite volume three-body interaction, the method is demonstrated by considering a toy model of three spinless particles interacting with pair-wise $\delta$-function potentials. The numerical results are compared with the exact solutions of three spinless bosons interaction when strength of short-range interactions are set equal for all pairs.

    ↳ hep-lathep-phPRD(2018)·55 citations
40. 40*

    Quenching the CME via the gravitational anomaly and holography

    Karl Landsteiner🇪🇸 · Esperanza Lopez🇪🇸 · Guillermo Milans del Bosch🇪🇸

    In the presence of a gravitational contribution to the chiral anomaly, the chiral magnetic effect induces an energy current proportional to the square of the temperature in equilibrium. In holography the thermal state corresponds to a black hole. We numerically study holographic quenches in which a planar shell of scalar matter falls into a black hole and rises its temperature. During the process the momentum density (energy current) is conserved. The energy current has two components, a non-dissipative one induced by the anomaly and a dissipative flow component. The dissipative component can be measured via the drag it asserts on an additional auxiliary color charge. Our results indicate strong suppression very far from equilibrium.

    ↳ hep-thcond-mat.mes-hallhep-phnucl-thPRL(2018)·18 citations
41. 41*

    Ward Identity and Scattering Amplitudes for Nonlinear Sigma Models

    Ian Low🇺🇸 · Zhewei Yin🇺🇸

    We present a Ward identity for nonlinear sigma models using generalized nonlinear shift symmetries, without introducing current algebra or coset space. The Ward identity constrains correlation functions of the sigma model such that the Adler's zero is guaranteed for $S$-matrix elements, and gives rise to a subleading single soft theorem that is valid at the quantum level and to all orders in the Goldstone decay constant. For tree amplitudes, the Ward identity leads to a novel Berends-Giele recursion relation as well as an explicit form of the subleading single soft factor. Furthermore, interactions of the cubic biadjoint scalar theory associated with the single soft limit, which was previously discovered using the Cachazo-He-Yuan representation of tree amplitudes, can be seen to emerge from matrix elements of conserved currents corresponding to the generalized shift symmetry.

    ↳ hep-thhep-phPRL(2018)·48 citations
42. 42*

    Tibet's Ali: A New Window to Detect the CMB Polarization

    Yong-Ping Li🇨🇳 · Yang Liu🇨🇳 · Si-Yu Li🇨🇳 · Hong Li🇨🇳 · Xinmin Zhang🇨🇳

    The Cosmic Microwave Background (CMB) Polarization plays an important role in current cosmological studies. CMB B-mode polarization is the most effective probe to primordial gravitational waves (PGWs) and a test of the inflation as well as other theories of the early universe such as bouncing and cyclic universe. So far, major ground-based CMB polarization experiments are located in the southern hemisphere.Recently, China has launched the Ali CMB Polarization Telescope (AliCPT) in Tibetan Plateau to measure CMB B mode polarization and detect the PGWs in northern hemisphere. AliCPT include two stages, the first one is to build a telescope at the 5250m site (AliCPT-1) and the second one is to have a more sensitive telescope at a higher altitude of about 6000m (AliCPT-2). In this paper, we report the atmospherical conditions, sky coverage and the current infrastructure associated with AliCPT. We analyzed the reanalysis data from MERRA-2 together with radiosonde data from the Ali Meteorological Service and found that the amount of water vapor has a heavy seasonal variation and October to March is the suitable observation time. We also found 95/150 GHz to be feasible for AliCPT-1 and higher frequencies to be possible for AliCPT-2. Then we analyzed the observable sky and the target fields, and showed that Ali provides us a unique opportunity to observe CMB with less foreground contamination in the northern hemisphere and is complementary to the existed southern CMB experiments. Together with the developed infrastructure, we point out that Ali opens a new window for CMB observation and will be one of the major sites in the world along with Antarctic and Atacama.

    ↳ astro-ph.IMastro-ph.COgr-qchep-ph+119 citations
43. 43*

    Search for 3rd generation superpartners with the ATLAS experiment

    Keisuke Yoshihara🇺🇸

    Two of the most important parameters in supersymmetry are the masses of the stop and sbottom, the supersymmetric partners of the third generation quarks. A stop mass lighter than 1 TeV is favored theoretically; however, "conventional" searches based on the simplified models have not produced experimental evidence for a light stop. It is possible that the light stop evades our searches due to a compressed sparticle mass spectrum. Therefore, the searches are extended to cover a broader range of signal scenarios with different mass splittings between the stop, neutralino(s), and chargino(s). The searches are then interpreted in the context of both simplified models and pMSSM models. Recent ATLAS results from searches for direct stop (sbottom) pair production are presented in final states with jets and missing transverse-momentum (and leptons). The analyses are based on 36 fb${}^{-1}$ of $\sqrt{s}$=13 TeV proton-proton collision data recorded with ATLAS detector at the LHC in 2015 and 2016.

    ↳ hep-exhep-ph0 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.