Wed·Jan 25, 2017Wednesday·January 25, 2017

1. 01*

   SModelS v1.1 user manual

   Federico Ambrogi🇦🇹 · Sabine Kraml🇫🇷 · Suchita Kulkarni🇦🇹 · Ursula Laa🇫🇷 · Andre Lessa🇧🇷 · Veronika Magerl🇩🇪 · Jory Sonneveld🇩🇪 · Michael Traub🇦🇹 · Wolfgang Waltenberger🇦🇹

   SModelS is an automatised tool for the interpretation of simplified model results from the LHC. It allows to decompose models of new physics obeying a Z2 symmetry into simplified model components, and to compare these against a large database of experimental results. The first release of SModelS, v1.0, used only cross section upper limit maps provided by the experimental collaborations. In this new release, v1.1, we extend the functionality of SModelS to efficiency maps. This increases the constraining power of the software, as efficiency maps allow to combine contributions to the same signal region from different simplified models. Other new features of version 1.1 include likelihood and chi-square calculations, extended information on the topology coverage, an extended database of experimental results as well as major speed upgrades for both the code and the database. We describe in detail the concepts and procedures used in SModelS, explaining in particular how upper limits and efficiency map results are dealt with in parallel. Detailed instructions for code usage are also provided.

   hep-phhep-exComput.Phys.Commun.(2018)·105 citations
2. 02*

   An Enhanced Threshold Resummation Formalism for Lepton Pair Production and Its Effects in the Determination of Parton Distribution Functions

   David Westmark🇺🇸 · J. F. Owens🇺🇸

   We demonstrate that theoretical predictions using current resummation techniques for the lepton pair production (LPP) rapidity and $x_F$ distributions can be inconsistent with data in high rapidity and $x_F$ kinematic regions by observing their effect in global fits of parton distribution functions (PDFs). We present an enhanced resummation technique for the LPP rapidity and $x_F$ distributions that agrees with LPP data. The enhanced resummation method is used in conjunction with threshold resummation in deep inelastic scattering (DIS) to perform two global fits of PDFs using the minimal and Borel prescriptions. The results are analyzed to determine the effect of threshold resummation on global fits of PDFs.

   hep-phPRD(2017)·44 citations
3. 03*

   A model of mesons in finite extra-dimension

   Jugal Lahkar🇮🇳 · D.K.Choudhury🇮🇳 · S.Roy🇮🇳 · N.S.Bordoloi🇮🇳

   Recently,problem of stability of H-atom has been reported in extra-finite dimension,and found out that it is stable in extra-finite dimension of size,$R\le \frac{a_0}{4}$,where,$a_0$ is the Bohr radius.Assuming that,the heavy flavoured mesons have also such stability controlled by the scale of coupling constant,we obtain corresponding QCD Bohr radius and it is found to be well within the present theoretical and experimental limit of higher dimension.We then study its consequences in their masses using effective string inspired potential model in higher dimension pursued by us.Within the uncertainty of masses of known Heavy Flavoured mesons the allowed range of extra dimension is $L\le 10^{-16}m$,which is well below the present theoretical and experimental limit,and far above the Planck length $\simeq 1.5\times 10^{-35}$ m.

   hep-phCan.J.Phys.(2018)·4 citations
4. 04*

   A new air-shower observable to constrain hadronic interaction models

   Raul R. Prado🇧🇷 · Vitor de Souza🇧🇷

   The energy spectrum of muons at ground level in air showers are studied and a new observable is proposed to constrain hadronic interaction models used in air shower simulations. An asymmetric Gaussian function is proposed to describe the muon ground energy spectrum and its parameters are studied regarding primary particle, energy and hadronic interaction models. Based on two realistic measurements of the muon density at a given distance from the shower axis, a new observable (\rmu) is defined. Considering realistic values of detector resolutions and number of measured events, it is also shown \rmu can be successfully used to constrain low and high hadronic interaction models. The study is focused in the energy range between $10^{17.5}$ and $10^{18.0}$ eV because of the importance of this interval for particle physics and astrophysical models. The constraining power of the new observable is shown to be large within current experimental capabilities.

   hep-phastro-ph.HEhep-exAstropart.Phys.(2017)·1 citation
5. 05*

   Impact of leptoquarks in semileptonic B decays

   Suchismita Sahoo🇮🇳 · Rukmani Mohanta🇮🇳 · Anjan K. Giri🇮🇳

   We study the impact of vector leptoquarks on the recent anomalies in semileptonic $B$ meson decays such as $R_K$ and $R_{D^{(\ast )}}$ etc. We constrain the leptoquark couplings by using the existing data on the branching ratios of $B_s\to l^{+}{l}^{-}$ and $\bar{B}\to X_s{l}^{+}{l}^{-}$ processes, where $l=e,\mu ,\tau$. We estimate the branching ratios of $\bar{B}\to D^{(\ast )}l{\bar{\nu }}_l$ processes using the constrained leptoquark parameter space. We also investigate the possibility of simultaneous explanation of $R_{D^{(\ast )}}$, $R_K$ anomalies in this model.

   hep-phPoS(2017)·1 citation
6. 06*

   Anomalous electrodynamics of neutral pion matter in strong magnetic fields

   Tomas Brauner🇳🇴 · Saurabh Kadam🇮🇳

   The ground state of quantum chromodynamics in sufficiently strong external magnetic fields and at moderate baryon chemical potential is a chiral soliton lattice (CSL) of neutral pions. We investigate the interplay between the CSL structure and dynamical electromagnetic fields. Our main result is that in presence of the CSL background, the two physical photon polarizations and the neutral pion mix, giving rise to two gapped excitations and one gapless mode with a nonrelativistic dispersion relation. The nature of this mode depends on the direction of its propagation, interpolating between a circularly polarized electromagnetic wave and a neutral pion surface wave, which in turn arises from the spontaneously broken translation invariance. Quite remarkably, there is a neutral-pion-like mode that remains gapped even in the chiral limit, in seeming contradiction to the Goldstone theorem. Finally, we have a first look at the effect of thermal fluctuations of the CSL, showing that even the soft nonrelativistic excitation does not lead to the Landau-Peierls instability. However, it leads to an anomalous contribution to pressure that scales with temperature and magnetic field as $T^{5/2}(B/f_{\pi }{)}^{3/2}$.

   hep-phhep-thJHEP(2017)·39 citations
7. 07*

   Lepton Flavour Violation in Left-Right Theory

   Pavel Fileviez Perez🇺🇸 · Clara Murgui🇪🇸

   We investigate the predictions for lepton flavour number violating processes in the context of a simple left-right symmetric theory. In this context neutrinos are Majorana fermions and their masses are generated at the quantum level through the Zee mechanism using the simplest Higgs sector. We show that the right handed neutrinos are generically light and can give rise to large lepton number violating contributions to rare processes. We discuss the correlation between the collider constrains and the predictions for lepton number violating processes. We find that using the predictions for mu to e gamma and mu to e conversion together with the collider signatures one could test this theory in the near future.

   hep-phhep-exPRD(2017)·23 citations
8. 08*

   Perturbative corrections to $B\to D$ form factors in QCD

   Yu-Ming Wang🇨🇳 · Yan-Bing Wei🇨🇳 · Yue-Long Shen🇨🇳 · Cai-Dian Lü🇨🇳

   We compute perturbative QCD corrections to $B\to D$ form factors at leading power in $\Lambda /m_b$, at large hadronic recoil, from the light-cone sum rules (LCSR) with $B$-meson distribution amplitudes in HQET. QCD factorization for the vacuum-to-$B$-meson correlation function with an interpolating current for the $D$-meson is demonstrated explicitly at one loop with the power counting scheme $m_c\sim \mathcal{O}\left(\sqrt{\Lambda m_b}\right)$. The jet functions encoding information of the hard-collinear dynamics in the above-mentioned correlation function are complicated by the appearance of an additional hard-collinear scale $m_c$, compared to the counterparts entering the factorization formula of the vacuum-to-$B$-meson correction function for the construction of $B\to \pi$ from factors. Inspecting the next-to-leading-logarithmic sum rules for the form factors of $B\to D\ell \nu$ indicates that perturbative corrections to the hard-collinear functions are more profound than that for the hard functions, with the default theory inputs, in the physical kinematic region. We further compute the subleading power correction induced by the three-particle quark-gluon distribution amplitudes of the $B$-meson at tree level employing the background gluon field approach. The LCSR predictions for the semileptonic $B\to D\ell \nu$ form factors are then extrapolated to the entire kinematic region with the $z$-series parametrization. Phenomenological implications of our determinations for the form factors $f_{BD}^{+,0}(q^2)$ are explored by investigating the (differential) branching fractions and the $R(D)$ ratio of $B\to D\ell \nu$ and by determining the CKM matrix element $|V_{cb}|$ from the total decay rate of $B\to D\mu {\nu }_{\mu }$.

   hep-phhep-exhep-latJHEP(2017)·87 citations
9. 09*

   High $p_{\mathrm{T}}$ spectra and anisotropy of light and heavy hadrons

   Peter Christiansen🇸🇪

   Data driven studies of heavy-ion results has played a big role in highlighting interesting features of these complex systems. In this proceeding, a simple QGP-brick interpretation of the $R_{\mathrm{AA}}$ and $v_2$ at high $p_{\mathrm{T}}$ ($p_{\mathrm{T}}\approx 10$ GeV/c) is presented. This interpretation draws attention to two fundamental questions: is there an effect of the asymmetric QGP expansion on the $v_2$ at high $p_{\mathrm{T}}$? is there an energy loss difference between quarks and gluons? Finally, it is discussed how these studies can be extended using Event-Shape Engineering and how they can be applied to compare the energy loss of light and heavy quarks.

   hep-phnucl-exNucl.Part.Phys.Proc.(2017)·0 citations
10. 10*

    Predictions for ${\Xi }_b^{-}\to {\pi }^{-}\left(D_s^{-}\right){\Xi }_c^0(2790)\left({\Xi }_c^0(2815)\right)$ and ${\Xi }_b^{-}\to {\bar{\nu }}_{l}l{\Xi }_c^0(2790)\left({\Xi }_c^0(2815)\right)$

    R. P. Pavao🇪🇸 · W. H. Liang🇨🇳 · J. Nieves🇪🇸 · E. Oset🇪🇸

    We have performed the calculations for the nonleptonic ${\Xi }_b^{-}\to {\pi }^{-}{\Xi }_c^0(2790)\left(J=\frac{1}{2}\right)$ and ${\Xi }_b^{-}\to {\pi }^{-}{\Xi }_c^0(2815)\left(J=\frac{3}{2}\right)$ and the same reactions replacing the ${\pi }^{-}$ by a $D_s^{-}$. At the same time we evaluate the semileptonic rates for ${\Xi }_b^{-}\to {\bar{\nu }}_{l}l{\Xi }_c^0(2790)$ and ${\Xi }_b^{-}\to {\bar{\nu }}_{l}l{\Xi }_c^0(2815)$. We look at the reactions from the perspective that the ${\Xi }_c^0(2790)$ and ${\Xi }_c^0(2815)$ resonances are dynamically generated from the pseudoscalar-baryon and vector-baryon interactions. We evaluate ratios of the rates of these reactions and make predictions that can be tested in future experiments. We also find that the results are rather sensitive to the coupling of the ${\Xi }_c^{\ast }$ resonances to the $D^{\ast }\Sigma$ and $D^{\ast }\Lambda$ components.

    hep-phEPJC(2017)·29 citations
11. 11*

    Top quark FCNC couplings at future circular hadron electron colliders

    H. Denizli🇹🇷 · A. Senol🇹🇷 · A. Yilmaz🇹🇷 · I. T. Cakir🇹🇷 · H. Karadeniz🇹🇷 · O. Cakir🇹🇷

    A study of single top quark production via flavor changing neutral current interactions at $tq\gamma$ vertices is performed at future circular hadron electron collider. The signal cross sections for the processes $e^{-}p\to e^{-}{W}^{\pm }q+X$ and $e^{-}p\to e^{-}{W}^{\pm }bq+X$ in the collision of electron beam with energy $E_e=$ 60 GeV and proton beam with energy $E_p=$ 50 TeV are calculated. In the analysis, the invariant mass distributions of three jets reconstructing top quark mass, requiring one b-tagged jet and other two jets reconstructing the $W$ mass are used to count signal and background events after all selection cuts. The upper limits on the anomalous flavor changing neutral current $tq\gamma$ couplings are found to be ${\lambda }_q<$ 0.01 at future circular hadron electron collider for $L_{int}=100$ fb${}^{-1}$ with the fast simulation of detector effects. Signal significance depending on the couplings ${\lambda }_q$ is analyzed and an enhanced sensitivity is found to the branching ratio BR($t\to q\gamma$) at the future circular hadron electron collider when compared to the current experimental results.

    hep-phPRD(2017)·18 citations
12. 12*

    Flavour mixings in flux compactifications

    Wilfried Buchmuller🇩🇪 · Julian Schweizer🇩🇪

    A multiplicity of quark-lepton families can naturally arise as zero-modes in flux compactifications. The flavour structure of quark and lepton mass matrices is then determined by the wave function profiles of the zero-modes. We consider a supersymmetric $SO(10)\times U(1)$ model in six dimensions compactified on the orbifold $T^2/{\mathbb{Z}}_2$ with Abelian magnetic flux. A bulk $16$-plet charged under the $U(1)$ provides the quark-lepton generations whereas two uncharged $10$-plets yield two Higgs doublets. Bulk anomaly cancellation requires the presence of additional $16$- and $10$-plets. The corresponding zero-modes form vectorlike split multiplets that are needed to obtain a successful flavour phenomenology. We analyze the pattern of flavour mixings for the two heaviest families of the Standard Model and discuss possible generalizations to three and more generations.

    hep-phhep-thPRD(2017)·40 citations
13. 13*

    Light Higgsino for Gauge Coupling Unification

    Kwang Sik Jeong🇰🇷

    We explore gauge coupling unification and dark matter in high scale supersymmetry where the scale of supersymmetry breaking is much above the weak scale. The gauge couplings unify as precisely as in low energy supersymmetry if the higgsinos, whose mass does not break supersymmetry, are much lighter than those obtaining masses from supersymmetry breaking. The dark matter of the universe can then be explained by the neutral higgsino or the gravitino. High scale supersymmetry with light higgsinos requires a large Higgs mixing parameter for electroweak symmetry breaking to take place. It is thus naturally realized in models where superparticle masses are generated at loop level while the Higgs mixing parameter is induced at tree level, like in anomaly and gauge mediation of supersymmetry breaking.

    hep-phPLB(2017)·5 citations
14. 14*

    Momentum anisotropy effects for quarkonium in a weakly-coupled quark-gluon plasma below the melting temperature

    Simone Biondini🇨🇭 · Nora Brambilla🇩🇪 · Miguel Angel Escobedo🇫🇮 · Antonio Vairo🇩🇪

    In the early stages of heavy-ion collisions, the hot QCD matter expands more longitudinally than transversely. This imbalance causes the system to become rapidly colder in the longitudinal direction and a local momentum anisotropy appears. In this paper, we study the heavy-quarkonium spectrum in the presence of a small plasma anisotropy. We work in the framework of pNRQCD at finite temperature. We inspect arrangements of non-relativistic and thermal scales complementary to those considered in the literature. In particular, we consider temperatures larger and Debye masses smaller than the binding energy, which is a temperature range relevant for presently running LHC experiments. In this setting we compute the leading thermal corrections to the binding energy and the thermal width induced by quarkonium gluo-dissociation.

    hep-phhep-thnucl-exnucl-thPRD(2017)·10 citations
15. 15*

    Simplified dark matter models with a spin-2 mediator at the LHC

    Sabine Kraml🇫🇷 · Ursula Laa🇫🇷 · Kentarou Mawatari🇫🇷 · Kimiko Yamashita🇯🇵

    We consider simplified dark matter models where a dark matter candidate couples to the standard model (SM) particles via an $s$-channel spin-2 mediator, and study constraints on the model parameter space from the current LHC data. Our focus lies on the complementarity among different searches, in particular monojet and multijet plus missing energy searches and resonance searches. For universal couplings of the mediator to SM particles, missing-energy searches can give stronger constraints than $WW$, $ZZ$, dijet, dihiggs, $t\bar{t}$, $b\bar{b}$ resonance searches in the low-mass region and/or when the coupling of the mediator to dark matter is much larger than its couplings to SM particles. The strongest constraints however come from diphoton and dilepton resonance searches. Only if these modes are suppressed, missing-energy searches can be competitive in constraining dark matter models with a spin-2 mediator.

    hep-phEPJC(2017)·47 citations
16. 16*

    On exponential suppression of the cosmological constant in non-SUSY strings at two loops and beyond

    Steven Abel🇬🇧 · Richard J. Stewart🇨🇭

    Two independent criteria are presented that together guarantee exponential suppression of the two-loop cosmological constant in non-supersymmetric heterotic strings. They are derived by performing calculations in both the full string theory and in its underlying effective field theory, and come respectively from contributions that involve only physical untwisted states, and contributions that include orbifold twisted states. The criteria depend purely on the spectrum and charges, so a model that satisfies them will do so with no fine-tuning. An additional consistency condition (emerging from the so-called separating degeneration limit of the two-loop diagram) is that the one-loop cosmological constant must also be suppressed, by Bose-Fermi degeneracy in the massless spectrum. We remark that theories of this kind, that have continued exponential suppression to higher orders, can form the basis for a string implementation of the "naturalness without supersymmetry" idea.

    ↳ hep-thhep-phPRD(2017)·56 citations
17. 17*

    Yangian and SUSY symmetry of High Spin Parton Splitting Amplitudes in Generalised Yang-Mills Theory

    Roland Kirschner🇩🇪 · George Savvidy🇬🇷

    We have calculated the high spin parton splitting amplitudes postulating the Yangian symmetry of the scattering amplitudes for tensorgluons. The resulting splitting amplitudes coincide with the earlier calculations, which were based on the BCFW recursion relations. The resulting formula unifies all known splitting probabilities found earlier in gauge field theories. It describes splitting probabilities for integer and half-integer spin particles. We also checked that the splitting probabilities fulfil generalised Kounnas-Ross N=1 supersymmetry relations hinting to the fact that the underlying theory can be formulated in an explicit supersymmetric manner.

    ↳ hep-thhep-phMod.Phys.Lett.A(2017)·6 citations
18. 18*

    Sommerfeld effect as the vertex correction in three-dimensional space

    Zhentao Zhang🇨🇳

    It is shown that the correction to the vertex for fermion pair annihilation and production in the low-energy region is equal to the value of the wave function for the two-body system at the origin. The procedure also shows directly that the emergence of the Sommerfeld effect in quantum mechanics is the product of the reduction of the vertex correction from four spacetime dimensions to three-dimensional space. Meanwhile, the reciprocal wave function is introduced into quantum mechanics.

    ↳ hep-thhep-phquant-ph0 citations
19. 19*

    Reconstructing CMB fluctuations and the mean reionization optical depth

    P. Daniel Meerburg🇨🇦 · Joel Meyers🇨🇦 · Kendrick M. Smith🇨🇦 · Alexander van Engelen🇨🇦

    The Thomson optical depth from reionization is a limiting factor in measuring the amplitude of primordial fluctuations, and hence in measuring physics that affects the low-redshift amplitude, such as the neutrino masses. Current constraints on the optical depth, based on directly measuring large-scale cosmic microwave background (CMB) polarization, are challenging due to foregrounds and systematic effects. Here, we consider an indirect measurement of large-scale polarization, using observed maps of small-scale polarization together with maps of fields that distort the CMB, such as CMB lensing and patchy reionization. We find that very futuristic CMB surveys will be able to reconstruct large-scale polarization, and thus the mean optical depth, using only measurements on small scales.

    ↳ astro-ph.COhep-phPRD(2017)·13 citations
20. 20*

    Quark Deconfinement in Rotating Neutron Stars

    R. D. Mellinger🇺🇸 · F. Weber🇺🇸 · W. Spinella🇺🇸 · G. A. Contrera🇺🇸 · M. G. Orsaria🇦🇷

    In this paper, we use a three flavor non-local Nambu--Jona-Lasinio (NJL) model, an~improved effective model of Quantum Chromodynamics (QCD) at low energies, to investigate the existence of deconfined quarks in the cores of neutron stars. Particular emphasis is put on the possible existence of quark matter in the cores of rotating neutron stars (pulsars). In contrast to non-rotating neutron stars, whose particle compositions do not change with time (are frozen in), the type and structure of the matter in the cores of rotating neutron stars depends on the spin frequencies of these stars, which opens up a possible new window on the nature of matter deep in the cores of neutron stars. Our study shows that, depending on mass and rotational frequency, up to around 8% of the mass of a massive neutron star may be in the mixed quark-hadron phase, if the phase transition is treated as a Gibbs transition. We also find that the gravitational mass at which quark deconfinement occurs in rotating neutron stars varies quadratically with spin frequency, which can be fitted by a simple formula.

    ↳ astro-ph.HEhep-phnucl-thUniverse(2017)·21 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.