Wed·Dec 9, 2015Wednesday·December 9, 2015

1. 01*

   Semileptonic decays ${\Lambda }_c^{+}\to \Lambda {\ell }^{+}{\nu }_{\ell }(\ell =e,\mu )$ in the covariant quark model and comparison with the new absolute branching fraction measurements of Belle and BESIII

   Thomas Gutsche🇩🇪 · Mikhail A. Ivanov🇷🇺 · Jurgen G. Korner🇩🇪 · Valery E. Lyubovitskij🇩🇪 · Pietro Santorelli🇮🇹

   We present precise theoretical predictions for the absolute branching fractions of ${\Lambda }_c^{+}\to \Lambda {\ell }^{+}{\nu }_{\ell }(\ell =e,\mu )$ decays in the covariant confined quark model. This study is motivated by two recent and accurate measurements of the absolute branching fractions of ${\Lambda }_c^{+}\to p{K}^{-}{\pi }^{+}$ and ${\Lambda }_c^{+}\to \Lambda e^{+}{\nu }_e$ by the Belle Collaboration at the KEKB and by the BESIII Collaboration at the BEPCII. Our predictions for the branching fractions are consistent with both experimental results. We also provide detailed numerical results for differential decay distributions and polarization observables.

   hep-phPRD(2016)·54 citations
2. 02*

   The ATLAS Diboson Resonance in Non-Supersymmetric SO(10)

   Jason L. Evans🇰🇷 · Natsumi Nagata🇺🇸 · Keith A. Olive🇺🇸 · Jiaming Zheng🇺🇸

   SO(10) grand unification accommodates intermediate gauge symmetries with which gauge coupling unification can be realized without supersymmetry. In this paper, we discuss the possibility that a new massive gauge boson associated with an intermediate gauge symmetry explains the excess observed in the diboson resonance search recently reported by the ATLAS experiment. The model we find has two intermediate symmetries, $SU(4{)}_C\otimes SU(2{)}_L\otimes SU(2{)}_R$ and $SU(3{)}_C\otimes SU(2{)}_L\otimes SU(2{)}_R\otimes U(1{)}_{B-L}$, where the latter gauge group is broken at the TeV scale. This model achieves gauge coupling unification with a unification scale sufficiently high to avoid proton decay. In addition, this model provides a good dark matter candidates, whose stability is guaranteed by a $Z_2$ symmetry present after the spontaneous breaking of the intermediate gauge symmetries. We also discuss prospects for testing these models in the forthcoming LHC experiments and dark matter detection experiments.

   hep-phJHEP(2016)·15 citations
3. 03*

   Amplitude Analysis for Mesons and Baryons: Tools and Technology

   C. Hanhart🇩🇪

   In these proceedings some facts about resonances are discussed focussing on the analytic properties of resonant amplitudes with special emphasis on model independent analyses. As an illustrative example of the latter point the decays B and B_s to J/psi pi pi are discussed in some detail.

   hep-phAIP Conf.Proc.(2016)·8 citations
4. 04*

   Low-Scale Gauge Mediation with a 100 TeV Gravitino

   Masaki Asano🇩🇪 · Yuichiro Nakai🇺🇸 · Norimi Yokozaki🇮🇹

   We propose a new framework of low-scale gauge-mediated supersymmetry (SUSY) breaking with a gravitino mass of O(100) TeV. The usual 4D gauge mediation models predict a light gravitino and suffer from cosmological problems. In our framework, a heavy gravitino in gauge mediation is realized with a flat extra-dimension, whose compactification scale is around the grand unified theory scale. Superparticle masses of the visible sector from gravity/anomaly mediation are suppressed, and they are purely generated by usual gauge mediation on the visible brane. Importantly, the Higgs Bmu-term vanishes at the leading order, which enables us to obtain the suitable mu-Bmu relation for the electroweak symmetry breaking. We discuss such models considering two possibilities of the SUSY breaking source: 1) Scherk-Schwarz SUSY breaking which we call Scherk-Schwarz Gauge Mediation and 2) gravitational SUSY breaking localized on a hidden brane. In the case 2), the cosmological moduli problem may be relaxed as well.

   hep-phhep-thPRD(2016)·5 citations
5. 05*

   Scalar doublet models confront $\tau$ and $b$ anomalies

   James M. Cline🇨🇦

   There are indications of a possible breakdown of the standard model, suggesting that $\tau$ lepton interactions violate flavor universality. BABAR, Belle and LHCb report high ratios of $B\to D^{(\ast )}\tau \nu$. There are long-standing excesses in $B\to \tau \nu$ and $W\to \tau \nu$ decays, and a deficit in inclusive $\tau$ to strange decays. We investigate whether two Higgs doublet models with the most general allowed couplings to quarks, and a large coupling to $\tau$ leptons, can explain these anomalies while respecting other flavor constraints and technical naturalness. Fits to $B\to D^{(\ast )}\tau \nu$ data require couplings of the new Higgs doublet to down-type quarks, opening the door to many highly constrained flavor-changing neutral current (FCNC) processes. We confront these challenges by introducing a novel ansatz that relates the new up- and down-type Yukawa couplings, and demonstrate viable values of the couplings that are free from fine tuning. LEP and LHC searches for new Higgs bosons decaying via $H^0\to {\tau }^{+}{\tau }^{-}$ and $H^{\pm }\to {\tau }^{\pm }\nu$ allow a window of masses $m_H=[100$-$125]$GeV and $m_{\pm }\sim 100$GeV that is consistent with the predictions of our model. Contamination of the $W^{+}\to {\tau }^{+}\nu$ signal by $H^{+}\to {\tau }^{+}\nu$ decays at LEP could explain the apparent $W\to \tau \nu$ excess. We predict that the branching ratio for $B_s\to {\tau }^{+}{\tau }^{-}$ is not far below its current limit of several percent. An alternative model with decays of $B\to D^{(\ast )}\tau {\nu }_s$ to a sterile neutrino is also argued to be viable.

   hep-phPRD(2016)·68 citations
6. 06*

   Stringy explanation of $b\to s{\ell }^{+}{\ell }^{-}$ anomalies

   Alejandro Celis🇩🇪 · Wan-Zhe Feng🇩🇪 · Dieter Lust🇩🇪

   We show that the recent anomalies in $b\to s{\ell }^{+}{\ell }^{-}$ transitions observed by the LHCb collaboration can be accommodated within string motivated models with a low mass $Z^{\prime }$ gauge boson. Such $Z^{\prime }$ gauge boson can be obtained in compactifications with a low string scale. We consider a class of intersecting D-brane models, in which different families of quarks and leptons are simultaneously realized at different D-brane intersections. The explanation of $b\to s{\ell }^{+}{\ell }^{-}$ anomalies via a stringy $Z^{\prime }$ sets important restrictions on these viable D-brane constructions.

   hep-phhep-thJHEP(2016)·35 citations
7. 07*

   Using sorted invariant mass variables to evade combinatorial ambiguities in cascade decays

   Doojin Kim🇺🇸 · Konstantin T. Matchev🇺🇸 · Myeonghun Park🇰🇷

   The classic method for mass determination in a SUSY-like cascade decay chain relies on measurements of the kinematic endpoints in the invariant mass distributions of suitable collections of visible decay products. However, the procedure is complicated by combinatorial ambiguities: e.g., the visible final state particles may be indistinguishable (as in the case of QCD jets), or one may not know the exact order in which they are emitted along the decay chain. In order to avoid such combinatorial ambiguities, we propose to treat the final state particles fully democratically and consider the sorted set of the invariant masses of all possible partitions of the visible particles in the decay chain. In particular, for a decay to N visible particles, one considers the sorted sets of all possible n-body invariant mass combinations (2 <= n <= N) and determines the kinematic endpoint m_(n,r)^max of the distribution of the r-th largest n-body invariant mass m_(n,r) for each possible value of n and r. For the classic example of a squark decay in supersymmetry, we provide analytical formulas for the interpretation of these endpoints in terms of the underlying physical masses. We point out that these measurements can be used to determine the structure of the decay topology, e.g., the number and position of intermediate on-shell resonances.

   hep-phhep-exJHEP(2016)·19 citations
8. 08*

   Reason for T2K to run in dominant neutrino mode for detecting CP violation

   Monojit Ghosh🇮🇳

   The long-baseline experiment T2K in Japan has collected data in the neutrino mode corresponding to an exposure of $6.57\times 10^{20}$ POT (Protons on Target) and currently it is running in the antineutrino mode. The main aim of the antineutrino run is to measure the leptonic phase ${\delta }_{CP}$ which may help to understand the matter-antimatter asymmetry of the universe. In this work we show that in T2K, antineutrinos are required only for removing the wrong octant solutions which in turn improves the CP sensitivity. If however the octant is known then pure neutrino run is capable of giving the maximum CP sensitivity. If we divide the total true parameter space into eight sets, then we find that T2K antineutrino run helps in improving the CP sensitivity for only two sets while for the remaining six combinations pure neutrino run gives the best CP sensitivity. Thus if the neutrino run is replaced by the antineutrino run then it causes a reduction in the CP sensitivity in 75$\%$ of the true parameter space due to lesser statistics. Thus it is worthwhile to study if the T2K antineutrino run can be reduced by the antineutrino runs of the other experiments, so that T2K can run in dominant neutrino mode to extract the best CP sensitivity. In this work we explore the possibility of the antineutrino component of NO$\nu$A and the atmospheric neutrino experiment ICAL@INO for compensating the antineutrino run of T2K.

   hep-phPRD(2016)·18 citations
9. 09*

   Hunting for neutral, long-lived exotica at the LHC using a missing transverse energy signature

   Alexander Belyaev🇬🇧 · Stefano Moretti🇬🇧 · Kilian Nickel🇩🇪 · Marc C. Thomas🇬🇧 · Ian Tomalin🇬🇧

   Searches at the Large Hadron Collider (LHC) for neutral, long-lived particles have historically relied on the detection of displaced particles produced by their decay $\text{within}$ the detector volume. In this paper we study the potential of the complementary signature comprising of the missing transverse energy ($E_T^{miss}$) signal, traditionally used to look for dark matter, e.g., the lightest supersymmetric particle (LSP), to extend the LHC coverage to models with long-lived (LL) particles when they decay $\text{outside}$ the detector. Using CMS and ATLAS analyses at the 8 TeV LHC, we set an upper limit at the 95% confidence level (CL) on the production cross sections for two specific scenarios: (i) a model with a heavy non-standard model Higgs boson decaying to a LL scalar and (ii) an R-parity violating RPV SUSY model with a LL neutralino. We show that this method can significantly extend the LHC sensitivity to neutral, LL particles with arbitrary large lifetimes and that the limits obtained from a $E_T^{miss}$ signal are comparable to those from displaced particle searches for decay distances above a few meters. Results obtained in this study do not not depend on the specific decay channel of the LL particle and therefore are model-independent in this sense. We provide limits for the whole two-dimensional plane in terms of the mass of the LL particle and the mass of the mediator up to masses of 2 TeV including particular benchmarks studied in the original experimental papers. We have made these limits available in the form of a grid which can be used for the interpretation of various other new physics models.

   hep-phJHEP(2016)·5 citations
10. 10*

    Leptogenesis from loop effects in curved spacetime

    Jamie I. McDonald🇬🇧 · Graham M. Shore🇬🇧

    We describe a new mechanism - radiatively-induced gravitational leptogenesis - for generating the matter-antimatter asymmetry of the Universe. We show how quantum loop effects in C and CP violating theories cause matter and antimatter to propagate differently in the presence of gravity, and prove this is forbidden in flat space by CPT and translation symmetry. This generates a curvature-dependent chemical potential for leptons, allowing a matter-antimatter asymmetry to be generated in thermal equilibrium in the early Universe. The time-dependent dynamics necessary for leptogenesis is provided by the interaction of the virtual self-energy cloud of the leptons with the expanding curved spacetime background, which violates the strong equivalence principle and allows a distinction between matter and antimatter. We show here how this mechanism is realised in a particular BSM theory, the see-saw model, where the quantum loops involve the heavy sterile neutrinos responsible for light neutrino masses. We demonstrate by explicit computation of the relevant two-loop Feynman diagrams how these radiative corrections display the necessary dependence on the sterile neutrino masses to generate an asymmetry, and show how the induced lepton asymmetry may be sufficiently large to play an important role in determining the baryon-to-photon ratio of the Universe.

    hep-phgr-qchep-thJHEP(2016)·15 citations
11. 11*

    Extracting the Kaon Collins function from $e^{+}{e}^{-}$ hadron pair production data

    M. Anselmino🇮🇹 · M. Boglione🇮🇹 · U. D'Alesio🇮🇹 · J.O. Gonzalez Hernandez🇮🇹 · S. Melis🇮🇹 · F. Murgia🇮🇹 · A. Prokudin🇺🇸

    The latest data released by the BaBar Collaboration on azimuthal correlations measured for pion-kaon and kaon-kaon pairs produced in $e^{+}{e}^{-}$ annihilations allow, for the first time, a direct extraction of the kaon Collins functions. These functions are then used to compute the kaon Collins asymmetries in Semi Inclusive Deep Inelastic Scattering processes, which result in good agreement with the measurements performed by the HERMES and COMPASS Collaborations.

    hep-phPRD(2016)·31 citations
12. 12*

    Energy spectra of massive two-body decay products and mass measurement

    Kaustubh Agashe🇺🇸 · Roberto Franceschini🇨🇭 · Sungwoo Hong🇺🇸 · Doojin Kim🇺🇸

    We have recently established a new method for measuring the mass of unstable particles produced at hadron colliders based on the analysis of the energy distribution of a massless product from their two-body decays. The central ingredient of our proposal is the remarkable result that, for an unpolarized decaying particle, the location of the peak in the energy distribution of the observed decay product is identical to the (fixed) value of the energy that this particle would have in the rest-frame of the decaying particle, which, in turn, is a simple function of the involved masses. In addition, we utilized the property that this energy distribution is symmetric around the location of peak when energy is plotted on a logarithmic scale. The general strategy was demonstrated in several specific cases, including both beyond the SM particles, as well as for the top quark. In the present work, we generalize this method to the case of a massive decay product from a two-body decay; this procedure is far from trivial because (in general) both the above- mentioned properties are no longer valid. Nonetheless, we propose a suitably modified parametrization of the energy distribution that was used successfully for the massless case, which can deal with the massive case as well. We establish the accuracy of this parametrization using concrete examples of energy spectra of Z bosons from the decay of a heavier stop into a Z boson and a lighter stop. We then study a realistic application for the same process, but now including dominant backgrounds and using foreseeable statistics at LHC14, in order to determine the performance of this method for an actual mass measurement. The upshot of our present and previous work is that, in spite of energy being a Lorentz-variant quantity, its distribution emerges as a powerful tool for mass measurement at hadron colliders.

    hep-phJHEP(2016)·18 citations
13. 13*

    Anisotropic Inflation with General Potentials

    Jiaming Shi🇨🇳 · Xiaotian Huang🇨🇳 · Taotao Qiu🇨🇳

    Anomalies in recent observational data indicate that there might be some "anisotropic hair" generated in an inflation period. To obtain general information about the effects of this anisotropic hair to inflation models, we studied anisotropic inflation models that involve one vector and one scalar using several types of potentials. We determined the general relationship between the degree of anisotropy and the fraction of the vector and scalar fields, and concluded that the anisotropies behave independently of the potentials. We also generalized our study to the case of multi-directional anisotropies.

    hep-phastro-ph.COgr-qchep-thSCPMA(2016)·1 citation
14. 14*

    The spin of the proton in chiral effective field theory

    Hongna Li🇨🇳 · P. Wang🇨🇳 · D. B. Leinweber🇦🇺 · A. W. Thomas🇦🇺

    Proton spin is investigated in chiral effective field theory through an examination of the singlet axial charge, $a_0$, and the two non-singlet axial charges, $a_3$ and $a_8$. Finite-range regularization is considered as it provides an effective model for estimating the role of disconnected sea-quark loop contributions to baryon observables. Baryon octet and decuplet intermediate states are included to enrich the spin and flavour structure of the nucleon, redistributing spin under the constraints of chiral symmetry. In this context, the proton spin puzzle is well understood with the calculation describing all three of the axial charges reasonably well. The strange quark contribution to the proton spin is negative with magnitude 0.01. With appropriate $Q^2$ evolution, we find the singlet axial charge at the experimental scale to be ${\hat{a}}_0=0.31_{-0.05}^{+0.04}$, consistent with the range of current experimental values.

    hep-phPRC(2016)·15 citations
15. 15*

    Non-Abelian chiral instabilities at high temperature on the lattice

    Yukinao Akamatsu🇺🇸 · Alexander Rothkopf🇩🇪 · Naoki Yamamoto🇯🇵

    We report on an exploratory lattice study on the phenomenon of chiral instabilities in non-Abelian gauge theories at high temperature. It is based on a recently constructed anomalous Langevin-type effective theory of classical soft gauge fields in the presence of a chiral number density $n_5=n_{\mathrm{R}}-n_{\mathrm{L}}$. Evaluated in thermal equilibrium using classical lattice techniques it reveals that the fluctuating soft fields indeed exhibit a rapid energy increase at early times and we observe a clear dependence of the diffusion rate of topological charge (sphaleron rate) on the the initial $n_5$, relevant in both early universe baryogenesis and relativistic heavy-ion collisions. The topological charge furthermore shows a drift among distinct vacuum sectors, roughly proportional to the initial $n_5$ and in turn the chiral imbalance is monotonously reduced as required by helicity conservation.

    hep-phhep-latJHEP(2016)·23 citations
16. 16*

    Next-to-minimal $R$-symmetric model: Dirac gaugino, Higgs mass and invisible width

    Hiroaki Nakano🇯🇵 · Masaki Yoshikawa

    We study a singlet extension of the minimal $U(1{)}_R$ symmetric model, which shares nice properties of Dirac gauginos and $R$-symmetric Higgs sector. At the same time, a superpotential coupling of $R$-charged singlet to the Higgs doublets can give a substantial contribution to the Higgs boson mass. We show that the 125 GeV Higgs boson is consistent with perturbative unification, even if the SUSY scale is as low as 1 TeV and if the $D$-term Higgs potential is suppressed as is often the case in Dirac gauginos. The model also contains a light scalar and fermion, pseudo-moduli and pseudo-Goldstino: The former gets a mass mainly from SUSY breaking soft terms, in addition to a small explicit $R$-symmetry breaking for the latter. We examine how the Higgs mass and width are affected by these light degrees of freedom. Specifically we find thatdepending on parameters of $R$-charged Higgses, the pseudo-moduli lighter than a half of the SM-Higgs boson mass is still allowed by the constraints from invisible decays of the $Z$ and Higgs bosons. We also find that such a light scalar can reduce the Higgs boson mass, at most by a few percents.

    hep-phPTEP(2016)·4 citations
17. 17*

    Neutrino phenomenology and scalar Dark Matter with $A_4$ flavor symmetry in Inverse and type II seesaw

    Ananya Mukherjee🇮🇳 · Mrinal Kumar Das🇮🇳

    We present a TeV scale seesaw mechanism for exploring the dark matter and neutrino phenomenology in the light of recent neutrino and cosmology data. A different realization of the Inverse seesaw(ISS) mechanism with $A_4$ flavor symmetry is being implemented as a leading contribution to the light neutrino mass matrix which usually gives rise to vanishing reactor mixing angle ${\theta }_{13}$. Using a non-diagonal form of Dirac neutrino mass matrix and $3\sigma$ values of mass square differences we parameterize the neutrino mass matrix in terms of Dirac Yukawa coupling "$y$". We then use type II seesaw as a perturbation which turns out to be active to have a non-vanishing reactor mixing angle without much disturbing the other neutrino oscillation parameters. Then we constrain a common parameter space satisfying the non-zero ${\theta }_{13}$, Yukawa coupling and the relic abundance of dark matter. Contributions of neutrinoless double beta decay are also included for standard as well as non-standard interaction. This study may have relevance in future neutrino and Dark Matter experiments.

    hep-phNPB(2016)·25 citations
18. 18*

    Blind spots for neutralino dark matter in the NMSSM

    Marcin Badziak🇵🇱 · Marek Olechowski🇵🇱 · Paweł Szczerbiak🇵🇱

    Spin-independent cross-section for neutralino dark matter scattering off nuclei is investigated in the NMSSM. Several classes of blind spots for direct detection of singlino-Higgsino dark matter are analytically identified, including such that have no analog in the MSSM. It is shown that mixing of the Higgs doublets with the scalar singlet has a big impact on the position of blind spots in the parameter space. In particular, this mixing allows for more freedom in the sign assignment for the parameters entering the neutralino mass matrix, required for a blind spot to occur, as compared to the MSSM or the NMSSM with decoupled singlet. Moreover, blind spots may occur for any composition of a singlino-Higgsino LSP. Particular attention is paid to cases with the singlet-dominated scalar lighter than the 125 GeV Higgs for which a vanishing tree-level spin-independent scattering cross-section may result from destructive interference between the Higgs and the singlet-dominated scalar exchange. Correlations of the spin-independent scattering cross-section with the Higgs observables are also discussed.

    hep-phJHEP(2016)·67 citations
19. 19*

    Novel effects in twist-three SSA

    I.V. Anikin🇷🇺 · O.V. Teryaev🇷🇺

    We discuss the role of gluon poles and the gauge invariance for the hadron tensors of Drell-Yan and direct photon production processes with the transversely polarized hadron. These hadron tensors are needed to construct the corresponding single spin asymmetries. For the Drell-Yan process, we perform our analysis within both the Feynman and axial-type (contour) gauges for gluons. In both the Feynman and contour gauges, we demonstrate that the gauge invariance leads to the need of the new (non-standard) diagrams. Moreover, in the Feynman gauge, we argue the absence of gluon poles in the correlators $⟨\bar{\psi }{\gamma }_{\perp }{A}^{+}\psi ⟩$ related traditionally to $dT(x,x)/dx$. As a result, these terms disappear from the final QED gauge invariant Drell-Yan hadron tensor. For the direct photon production, by using the contour gauge for gluon fields, we find that there are new twist-$3$ terms present in the hadron tensor of the considering process in addition to the standard twist-$3$ terms.

    hep-phJ.Phys.Conf.Ser.(2016)·0 citations
20. 20*

    One-loop corrections to $h\to b\bar{b}$ and $h\to \tau \bar{\tau }$ decays in the Standard Model Dimension-6 EFT: four-fermion operators and the large-$m_t$ limit

    Rhorry Gauld🇬🇧 · Benjamin D. Pecjak🇬🇧 · Darren J. Scott🇬🇧

    We calculate a set of one-loop corrections to $h\to b\bar{b}$ and $h\to \tau \bar{\tau }$ decays in the dimension-6 Standard Model effective field theory (SMEFT). In particular, working in the limit of vanishing gauge couplings, we calculate directly in the broken phase of the theory all large logarithmic corrections and in addition the finite corrections in the large-$m_t$ limit. Moreover, we give exact results for one-loop contributions from four-fermion operators. We obtain these corrections within an extension of the widely used on-shell renormalisation scheme appropriate for SMEFT calculations, and show explicitly how UV divergent bare amplitudes from a total of 21 different SMEFT operators are rendered finite within this scheme. As a by-product of the calculation, we also compute to one-loop order the logarithmically enhanced and finite large-$m_t$ corrections to muon decay in the limit of vanishing gauge couplings, which is necessary to implement the $G_F$ input parameter scheme within the SMEFT.

    hep-phJHEP(2016)·74 citations
21. 21*

    QCD resummations for boosted top production

    Andrea Ferroglia🇺🇸 · Benjamin D. Pecjak🇬🇧 · Darren J. Scott🇬🇧 · Li Lin Yang🇨🇳

    We present new results for QCD corrections to the top-pair invariant mass and top-quark $p_T$ distributions in boosted top-quark pair production at hadron colliders. They are derived from a formalism which allows the joint resummation of soft and small-mass logarithms at NNLL${}^{\prime }$ order, thus taking into account all potentially large corrections in the boosted regime, where the partonic center-of-mass energy is parameterically much larger than the mass of the top quark. We match these results with those from standard soft-gluon resummation away from the small-mass limit to NNLL order and also with NLO fixed-order calculations, so that our results are valid in the maximum possible range of phase space. The resummation effects on the $p_T$ and top-pair invariant mass distributions are significant, bringing theory predictions into better agreement with experimental data compared to pure NLO calculations.

    hep-phPoS(2016)·9 citations
22. 22*

    Matching lightcone- and anomaly-sum-rule predictions for the pion-photon transition form factor

    A. G. Oganesian🇷🇺 · A. V. Pimikov🇷🇺 · N. G. Stefanis🇩🇪 · O. V. Teryaev🇷🇺

    The pion-photon transition form factor is studied by employing two types of Sum Rules: Light Cone Sum Rules (LCSR) and Anomaly Sum Rules (ASR). By comparing the predictions for the pion-photon transition form factor, obtained from these two approaches, the applicability limit of the LCSRs at low momenta is determined. Reciprocally, the ASR threshold dependence on the momentum was extracted using our LCSR-based method in combination with two different types of pion distribution amplitudes and found that at higher Q2 it approaches a constant.

    hep-phPRD(2016)·14 citations
23. 23*

    Spin-Directed Momentum Transfers in SIDIS Baryon Production

    Dennis Sivers🇺🇸

    The measurement of transverse single-spin asymmetries for baryon production in the target fragmentation region of semi-inclusive deep-inelastic scattering (SIDIS), can produce important insight into those nonperturbative aspects of QCD directly associated with confinement and with the dynamical breaking of chiral symmetry. We discuss here, interns of spin-directed momentum transfers, the powerful quantum field-theoretical constraints on the spin-orbit dynamics underlying these transverse spin observables. The spin-directed momentum shifts, originating either in the target nucleon or in the QCD jets produced in the deep inelastic scattering process, represent significant quantum entanglement effects connecting information from current fragmentation with observables in target fragmentation.

    hep-phEPJ Web Conf.(2016)·0 citations
24. 24*

    Higher Order QCD predictions for Associated Higgs production with anomalous couplings to gauge bosons

    Ken Mimasu🇬🇧 · Veronica Sanz🇬🇧 · Ciaran Williams🇺🇸

    We present predictions for the associated production of a Higgs boson at NLO+PS accuracy, including the effect of anomalous interactions between the Higgs and gauge bosons. We present our results in different frameworks, one in which the interaction vertex between the Higgs boson and Standard Model $W$ and $Z$ bosons is parameterized in terms of general Lorentz structures, and one in which Electroweak symmetry breaking is manifestly linear and the resulting operators arise through a six-dimensional effective field theory framework. We present analytic calculations of the Standard Model and Beyond the Standard Model contributions, and discuss the phenomenological impact of the higher order pieces. Our results are implemented in the NLO Monte Carlo program MCFM, and interfaced to shower Monte Carlos through the {\sc Powheg} box framework.

    hep-phhep-exJHEP(2016)·91 citations
25. 25*

    Composite Higgs model at a conformal fixed point

    R.C. Brower🇺🇸 · A. Hasenfratz🇺🇸 · C. Rebbi🇺🇸 · E. Weinberg🇺🇸 · O. Witzel🇬🇧

    We propose to construct a chirally broken model based on the infrared fixed point of a conformal system by raising the mass of some flavors while keeping the others massless. In the infrared limit the massive fermions decouple and the massless fermions break chiral symmetry. The running coupling of this system "walks" and the energy range of walking can be tuned by the mass of the heavy flavors. Renormalization group considerations predict that the spectrum of such a system shows hyperscaling. We have studied a model with four light and eight heavy flavors coupled to SU(3) gauge fields and verified the above expectations. We determined the mass of several hadronic states and found that some of them are in the 2-3 TeV range if the scale is set by the pseudoscalar decay constant $F_{\pi }\approx 250$ GeV. The $0^{++}$ scalar state behaves very differently from the other hadronic states. In most of our simulations it is nearly degenerate with the pion and we estimate its mass to be less than half of the vector resonance mass.

    hep-phhep-latPRD(2016)·72 citations
26. 26*

    Neutrino energy transport in weak decoupling and big bang nucleosynthesis

    E. Grohs🇺🇸 · G. M. Fuller🇺🇸 · C. T. Kishimoto🇺🇸 · M. W. Paris🇺🇸 · A. Vlasenko🇺🇸

    We calculate the evolution of the early universe through the epochs of weak decoupling, weak freeze-out and big bang nucleosynthesis (BBN) by simultaneously coupling a full strong, electromagnetic, and weak nuclear reaction network with a multi-energy group Boltzmann neutrino energy transport scheme. The modular structure of our code provides the ability to dissect the relative contributions of each process responsible for evolving the dynamics of the early universe in the absence of neutrino flavor oscillations. Such an approach allows a detailed accounting of the evolution of the ${\nu }_e$, ${\bar{\nu }}_e$, ${\nu }_{\mu }$, ${\bar{\nu }}_{\mu }$, ${\nu }_{\tau }$, ${\bar{\nu }}_{\tau }$ energy distribution functions alongside and self-consistently with the nuclear reactions and entropy/heat generation and flow between the neutrino and photon/electron/positron/baryon plasma components. This calculation reveals nonlinear feedback in the time evolution of neutrino distribution functions and plasma thermodynamic conditions (e.g., electron-positron pair densities), with implications for: the phasing between scale factor and plasma temperature; the neutron-to-proton ratio; light-element abundance histories; and the cosmological parameter \neff. We find that our approach of following the time development of neutrino spectral distortions and concomitant entropy production and extraction from the plasma results in changes in the computed value of the BBN deuterium yield. For example, for particular implementations of quantum corrections in plasma thermodynamics, our calculations show a $0.4\%$ increase in deuterium. These changes are potentially significant in the context of anticipated improvements in observational and nuclear physics uncertainties.

    ↳ astro-ph.COhep-phPRD(2016)·162 citations
27. 27*

    Oscillatory Attractors: A New Cosmological Phase

    Jasdeep S. Bains🇺🇸 · Mark P. Hertzberg🇺🇸 · Frank Wilczek🇺🇸

    In expanding FRW spacetimes, it is usually the case that homogeneous scalar fields redshift and their amplitudes approach limiting values: Hubble friction usually ensures that the field relaxes to its minimum energy configuration, which is usually a static configuration. Here we discover a class of relativistic scalar field models in which the attractor behavior is the field oscillating indefinitely, with finite amplitude, in an expanding FRW spacetime, despite the presence of Hubble friction. This is an example of spontaneous breaking of time translation symmetry. We find that the effective equation of state of the field has average value $⟨w⟩=-1$, implying that the field itself could drive an inflationary or dark energy dominated phase. This behavior is reminiscent of ghost condensate models, but in the new models, unlike in the ghost condensate models, the energy-momentum tensor is time dependent, so that these new models embody a more definitive breaking of time translation symmetry. We explore (quantum) fluctuations around the homogeneous background solution, and find that low $k$-modes can be stable, while high $k$-modes are typically unstable. We discuss possible interpretations and implications of that instability.

    ↳ hep-thastro-ph.COgr-qchep-phJCAP(2017)·28 citations
28. 28*

    Extra dimension-inspired models: Z', W', dijet resonances, black hole searches

    Tobias Pook🇩🇪

    I give a summary of BSM searches performed by the ATLAS and CMS experiments with an focus on heavy gauge bosons, extra dimensions and quantum black holes. The presented results use data collected during 2012 when the LHC operated at an center of mass energy of $\sqrt{s}$ = 8 TeV.

    ↳ hep-exhep-ph1 citation
29. 29*

    The Epoch of Reionization in the R_h=ct Universe

    Fulvio Melia🇺🇸 · Marco Fatuzzo🇺🇸

    The measured properties of the epoch of reionization (EoR) show that reionization probably began around z ~ 12-15 and ended by z=6. In addition, a careful analysis of the fluctuations in the cosmic microwave background indicate a scattering optical depth tau ~ 0.066+/-0.012 through the EoR. In the context of LCDM, galaxies at intermediate redshifts and dwarf galaxies at higher redshifts now appear to be the principal sources of UV ionizing radiation, but only for an inferred (ionizing) escape fraction f_ion ~ 0.2, which is in tension with other observations that suggest a value as small as ~ 0.05. In this paper, we examine how reionization might have progressed in the alternative Friedmann-Robertson Walker cosmology known as the R_h=ct Universe, and determine the value of f_ion required with this different rate of expansion. We find that R_h=ct accounts quite well for the currently known properties of the EoR, as long as its fractional baryon density falls within the reasonable range 0.026 < Omega_b < 0.037. This model can also fit the EoR data with f_ion ~ 0.05, but only if the Lyman continuum photon production is highly efficient and Omega_b ~ 0.037. These results are still preliminary, however, given their reliance on a particular form of the star-formation rate density, which is still uncertain at very high redshifts. It will also be helpful to reconsider the EoR in R_h=ct when complete structure formation models become available.

    ↳ astro-ph.COastro-ph.GAhep-phMNRAS(2016)·18 citations
30. 30*

    CP violation and Kaon weak matrix elements from Lattice QCD

    Nicolas Garron🇬🇧

    In this short review, I present the recent lattice computations of kaon weak matrix elements relevant to $K\to \pi \pi$ decays and neutral kaon mixing. These matrix elements are key to the theoretical determination of the CP violation parameters $ϵ$ and ${ϵ}^{\prime }$ . Impressive progress have been achieved recently, in particular the first realistic computation of ${ϵ}^{\prime }/ϵ$ with physical kinematics has been reported in [1]. The novelty is the $\Delta I=1/2$ channel, whereas the $\Delta I=3/2$ contribution is now computed at several values of the lattice spacing and extrapolated to the continuum limit. I will also present the status of $B_K$ and discuss its error budget, with a particular emphasis on the perturbative error. Finally I will review the matrix elements of neutral kaon mixing beyond the standard model and will argue that the discrepancy observed by different collaborations could be explained by the renormalisation procedure of the relevant four-quark operators.

    ↳ hep-lathep-phPoS(2016)·6 citations
31. 31*

    Quantum gravity without vacuum dispersion

    Daniel Coumbe🇩🇰

    A generic prediction of quantum gravity is the vacuum dispersion of light, and hence that a photon's speed depends on its energy. We present further numerical evidence for a scale dependent speed of light in the causal dynamical triangulation (CDT) approach to quantum gravity. We show that the observed scale dependent speed of light in CDT can be accounted for by a scale dependent transformation of geodesic distance, whose specific functional form implies a discrete equidistant area spectrum. We make two non-trivial tests of the proposed scale transformation: a comparison with the leading order quantum correction to the gravitational potential and a comparison with the generalised uncertainty principle. In both cases, we obtain the same functional form. However, contrary to the widespread prediction of vacuum dispersion in quantum gravity, numerous experiments have now definitively ruled out linear vacuum dispersion beyond Planckian energy scales, and have now even constrained quadratic dispersion. Motivated by these experimental constraints we seek to reconcile quantum gravity with the absence of vacuum dispersion. We point out that given a scale dependent geodesic distance, a scale dependent time interval becomes essential to maintaining an invariant speed of light. We show how a particular scale dependent time interval allows a photon's speed to remain independent of its energy.

    ↳ hep-thgr-qchep-phInt.J.Mod.Phys.D(2017)·18 citations
32. 32*

    On Building superpotentials in F- GUTs

    E. H. Saidi🇲🇦

    Using characters of finite group representations, we construct the fusion algebras of operators of the spectrum of F- theory GUTs. These fusion relations are used in building monodromy invariant superpotentials of the low energy effective 4d $\mathcal{N}=1$ supersymmetric GUT models.

    ↳ hep-thhep-phPTEP(2016)·4 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.