Thu·Mar 30, 2017Thursday·March 30, 2017

1. 01*

   Saxion Cosmology for Thermalized Gravitino Dark Matter

   Raymond T. Co🇺🇸 · Francesco D'Eramo🇺🇸 · Lawrence J. Hall🇺🇸 · Keisuke Harigaya🇺🇸

   In all supersymmetric theories, gravitinos, with mass suppressed by the Planck scale, are an obvious candidate for dark matter; but if gravitinos ever reached thermal equilibrium, such dark matter is apparently either too abundant or too hot, and is excluded. However, in theories with an axion, a saxion condensate is generated during an early era of cosmological history and its late decay dilutes dark matter. We show that such dilution allows previously thermalized gravitinos to account for the observed dark matter over very wide ranges of gravitino mass, keV < $m_{3/2}$ < TeV, axion decay constant, $10^9$ GeV < $f_a$ < $10^{16}$ GeV, and saxion mass, 10 MeV < $m_s$ < 100 TeV. Constraints on this parameter space are studied from BBN, supersymmetry breaking, gravitino and axino production from freeze-in and saxion decay, and from axion production from both misalignment and parametric resonance mechanisms. Large allowed regions of $(m_{3/2},f_a,m_s)$ remain, but differ for DFSZ and KSVZ theories. Superpartner production at colliders may lead to events with displaced vertices and kinks, and may contain saxions decaying to $(WW,ZZ,hh),gg,\gamma \gamma$ or a pair of Standard Model fermions. Freeze-in may lead to a sub-dominant warm component of gravitino dark matter, and saxion decay to axions may lead to dark radiation.

   hep-phastro-ph.COJHEP(2017)·24 citations
2. 02*

   Absorptive corrections for vector mesons. Matching to complex mass scheme and longitudinal corrections

   L. A. Jiménez Pérez🇲🇽 · G. Toledo Sánchez🇲🇽

   Unstable spin-1 particles are properly described by including absorptive corrections to the electromagnetic vertex and propagator, without breaking the electromagnetic gauge invariance. We show that the modified propagator can be set into a complex mass form, provided the mass and the width parameters, which are properly defined at the pole position, are replaced by energy dependent functions fulfilling the same requirements at the pole. We exemplify the case for the $K^{\ast }(892)$ vector meson, where the mass function deviates around 2 MeV from the $K\pi$ threshold to the pole position. The absorptive correction depends on the mass of the particles in the loop. For vector mesons, whose main decay is into two pseudoscalar mesons ($P{P}^{\prime }$), the flavor symmetry breaking induces a correction to the longitudinal part of the propagator. Considering the ${\tau }^{-}\to K_S{\pi }^{-}{\nu }_{\tau }$ decay, we illustrate these corrections by obtaining the modified vector and scalar form factors. The $K_S{\pi }^{-}$ spectrum is described considering the $K^{\ast }(892)$ and $K^{{}^{\prime }\ast }(1410)$ vectors and one scalar particle. Nonetheless, for this case, the correction to the scalar form factor is found to be negligible.

   hep-phnucl-thJ.Phys.G(2017)·8 citations
3. 03*

   Triangle mechanisms in the build up and decay of the $N^{\ast }(1875)$

   Daris Samart🇹🇭 · Wei-hong Liang🇨🇳 · Eulogio Oset🇪🇸

   We have studied the $N^{\ast }(1875)(3/2^{-})$ resonance with a multichannel unitary scheme, considering the $\Delta \pi$ and ${\Sigma }^{\ast }K$, with their interaction extracted from chiral Lagrangians, and then have added two more channels, the $N^{\ast }(1535)\pi$ and $N\sigma$, which proceed via triangle diagrams involving the ${\Sigma }^{\ast }K$ and $\Delta \pi$ respectively in the intermediate states. The triangle diagram in the $N^{\ast }(1535)\pi$ case develops a singularity at the same energy as the resonance mass. We determine the couplings of the resonance to the different channels and the partial decay widths. We find a very large decay width to ${\Sigma }^{\ast }K$, and also see that, due to interference with other terms, the $N\sigma$ channel has an important role in the $\pi \pi$ mass distributions at low invariant masses, leading to an apparently large $N\sigma$ decay width. A discussion is done, justifying the convenience of an experimental reanalysis of this resonance to the light of the findings of the paper, using multichannel unitary schemes.

   hep-phnucl-thPRC(2017)·23 citations
4. 04*

   Geometric phase and neutrino mass hierarchy problem

   Khushboo Dixit🇮🇳 · Ashutosh Kumar Alok🇮🇳 · Subhashish Banerjee🇮🇳 · Dinesh Kumar🇮🇳

   We study the geometric phase for neutrinos at various man-made facilities, such as the reactor and accelerator neutrino experiments. The analysis is done for the three flavor neutrino scenario, in the presence of matter and for general, noncyclic paths. The geometric phase is seen to be sensitive to the CP violating phase in the leptonic sector and the sign ambiguity in Delta_{31}. We find that for neutrino experimental facilities where the geometric phase can complete one cycle, all the phase curves corresponding to different values of CP violating phase, converge to a single point, called the cluster point. There are two distinct cluster points for positive and negative signs of Delta_{31}. Thus the geometric phase can contribute to our understanding of the neutrino mass hierarchy problem.

   hep-phquant-phJ.Phys.G(2018)·13 citations
5. 05*

   A novel mathematical construct for the family of leptonic mixing patterns

   Shu-jun Rong🇨🇳

   In order to induce a family of mixing patterns of leptons which accommodate the experimental data with a simple mathematical construct, we construct a novel object from the hybrid of two elements of a finite group with a parameter $\theta$. This construct is an element of a mathematical structure called group-algebra. It could reduce to a generator of a cyclic group if $\theta /2\pi$ is a rational number. We discuss a specific example on the base of the group $S_4$. This example shows that infinite cyclic groups could give the viable mixing patterns for Dirac neutrinos.

   hep-ph2 citations
6. 06*

   Flavour Anomalies in $b\to s{\ell }^{+}{\ell }^{-}$ Processes - a round table Discussion

   Tom Blake🇬🇧 · Marco Gersabeck🇬🇧 · Lars Hofer🇪🇸 · Sebastian Jäger🇬🇧 · Zhaofeng Liu🇨🇳 · Roman Zwicky🇬🇧

   Precision measurements of flavour observables provide powerful tests of many extensions of the Standard Model. This contribution covers a range of flavour measurements of $b\to s{\ell }^{+}{\ell }^{-}$ transitions, several of which are in tension with the Standard Model of particle physics, as well as their theoretical interpretation. The basics of the theoretical background are discussed before turning to the main question of the field: whether the anomalies can be explained by QCD effects or whether they may be indicators of effects beyond the Standard Model.

   hep-phhep-exEPJ Web Conf.(2017)·12 citations
7. 07*

   Baryogenesis via Dark Matter-Induced Symmetry Breaking in the Early Universe

   Jeremy Sakstein🇺🇸 · Mark Trodden🇺🇸

   We put forward a new proposal for generating the baryon asymmetry of the universe by making use of the dynamics of a $\mathrm{U}(1)$ scalar field coupled to dark matter. High dark matter densities cause the $\mathrm{U}(1)$ symmetry to break spontaneously so that the field acquires a large vacuum expectation value. The symmetry is restored when the density redshifts below a critical value, resulting in the coherent oscillation of the scalar field. A net $B-L$ number can be generated either via baryon number-conserving couplings to the standard model or through small symmetry-violating operators and the subsequent decay of the scalar condensate.

   hep-phastro-ph.COgr-qchep-thPLB(2017)·9 citations
8. 08*

   Driving Miss Data: Going up a gear to NNLO

   John M. Campbell🇺🇸 · R. Keith Ellis🇬🇧 · Ciaran Williams🇺🇸

   In this paper we present a calculation of the $\gamma +j$ process at next-to-next-to-leading order (NNLO) in QCD and compare the resulting predictions to 8 TeV CMS data. We find good agreement with the shape of the photon $p_T$ spectrum, particularly after the inclusion of additional electroweak corrections, but there is a tension between the overall normalization of the theoretical prediction and the measurement. We use our results to compute the ratio of $Z(\to {\ell }^{+}{\ell }^{-})+j$ to $\gamma +j$ events as a function of the vector boson transverse momentum at NNLO, a quantity that is used to normalize $Z(\to \nu \overline{\nu })+j$ backgrounds in searches for dark matter and supersymmetry. Our NNLO calculation significantly reduces the theoretical uncertainty on this ratio, thus boosting its power for future searches of new physics.

   hep-phhep-exPRD(2017)·48 citations
9. 09*

   Spontaneous CP-violation in the Simplest Little Higgs Model and its Future Collider Tests: the Scalar Sector

   Ying-nan Mao🇨🇳

   We proposed the spontaneous CP-violation in the Simplest Little Higgs model. In this model, the pseudoscalar field can acquire a nonzero vacuum expected value. It leads to a mixing between the two scalars with different CP-charge, which means spontaneous CP-violation happens. It is also a connection between composite Higgs mechanism and CP-violation. Facing the experimental constraints, the model is still alive for both scenarios in which the extra scalar appears below or around the electro-weak scale. We also discussed the future collider tests on CP-violation in the scalar sector through measuring $h_{2}ZZ$ and $h_1{h}_2{Z}^{\prime }$ vertices (see the definitions of the particles in the text) which provides new motivations on future $e^{+}{e}^{-}$ and $pp$ colliders. It also shows the importance of the vector-vector-scalar- and vector-scalar-scalar-type vertices to discover CP-violation effects in the scalar sector.

   hep-phPRD(2018)·13 citations
10. 10*

    Implications of Mixed Axion-Neutralino Dark Matter

    Hasan Serce🇺🇸

    The lack of evidence for weak scale supersymmetry from LHC Run-I and Run-II results along with null results from direct/indirect dark matter detection experiment have caused a paradigm shift in expected phenomenology of SUSY models. The SUSY dark matter candidate, neutralino ${\tilde{Z}}_1$, can only satisfy the measured dark matter abundance due to resonance- and co-annihilations in cMSSM model. Moreover, viable parameter space is highly fine-tuned in the cMSSM. In models that can still satisfy the naturalness condition such as NUHM2, the neutralino is underproduced due to its higgsino nature. Neutralino combined with axion that solves the strong CP problem can explain the observed dark matter in the universe. Here I briefly discuss implications of the mixed axion-neutralino scenario.

    hep-phAIP Conf.Proc.(2017)·1 citation
11. 11*

    Extraction of partonic transverse momentum distributions from semi-inclusive deep-inelastic scattering, Drell-Yan and Z-boson production

    Alessandro Bacchetta🇮🇹 · Filippo Delcarro🇮🇹 · Cristian Pisano (INFN, Pavia and Pavia U.)🇮🇹 · Marco Radici (INFN, Pavia)🇮🇹 · Andrea Signori (Jefferson Lab)🇺🇸

    We present an extraction of unpolarized partonic transverse momentum distributions (TMDs) from a simultaneous fit of available data measured in semi-inclusive deep-inelastic scattering, Drell-Yan and Z-boson production. To connect data at different scales, we use TMD evolution at next-to-leading logarithmic accuracy. The analysis is restricted to the low-transverse-momentum region, with no matching to fixed-order calculations at high transverse momentum. We introduce specific choices to deal with TMD evolution at low scales, of the order of 1 GeV${}^2$. This could be considered as a first attempt at a global fit of TMDs.

    hep-phJHEP(2017)·302 citations
12. 12*

    In Pursuit of New Physics with $B_{s,d}^0\to {\ell }^{+}{\ell }^{-}$

    Robert Fleischer🇳🇱 · Ruben Jaarsma🇳🇱 · Gilberto Tetlalmatzi-Xolocotzi🇳🇱

    Leptonic rare decays of $B_{s,d}^0$ mesons offer a powerful tool to search for physics beyond the Standard Model. The $B_s^0\to {\mu }^{+}{\mu }^{-}$ decay has been observed at the Large Hadron Collider and the first measurement of the effective lifetime of this channel was presented, in accordance with the Standard Model. On the other hand, $B_s^0\to {\tau }^{+}{\tau }^{-}$ and $B_s^0\to e^{+}{e}^{-}$ have received considerably less attention: while LHCb has recently reported a first upper limit of $6.8\times 10^{-3}$ (95% C.L.) for the $B_s^0\to {\tau }^{+}{\tau }^{-}$ branching ratio, the upper bound $2.8\times 10^{-7}$ (90% C.L.) for the branching ratio of $B_s^0\to e^{+}{e}^{-}$ was reported by CDF back in 2009. We discuss the current status of the interpretation of the measurement of $B_s^0\to {\mu }^{+}{\mu }^{-}$, and explore the space for New-Physics effects in the other $B_{s,d}^0\to {\ell }^{+}{\ell }^{-}$ decays in a scenario assuming flavour-universal Wilson coefficients of the relevant four-fermion operators. While the New-Physics effects are then strongly suppressed by the ratio $m_{\mu }/m_{\tau }$ of the lepton masses in $B_s^0\to {\tau }^{+}{\tau }^{-}$, they are hugely enhanced by $m_{\mu }/m_e$ in $B_s^0\to e^{+}{e}^{-}$ and may result in a $B_s^0\to e^{+}{e}^{-}$ branching ratio as large as about 5 times the one of $B_s^0\to {\mu }^{+}{\mu }^{-}$, which is about a factor of 20 below the CDF bound; a similar feature arises in $B_d^0\to e^{+}{e}^{-}$. Consequently, it would be most interesting to search for the $B_{s,d}^0\to e^{+}{e}^{-}$ channels at the LHC and Belle II, which may result in an unambiguous signal for physics beyond the Standard Model.

    hep-phhep-exJHEP(2017)·67 citations
13. 13*

    $B_s\to D_s\ell \nu$ Form Factors and the Fragmentation Fraction Ratio $f_s/f_d$

    Christopher J Monahan🇺🇸 · Heechang Na🇺🇸 · Chris M Bouchard🇬🇧 · G Peter Lepage🇺🇸 · Junko Shigemitsu🇺🇸

    We present a lattice quantum chromodynamics determination of the scalar and vector form factors for the $B_s\to D_s\ell \nu$ decay over the full physical range of momentum transfer. In conjunction with future experimental data, our results will provide a new method to extract $|V_{cb}|$, which may elucidate the current tension between exclusive and inclusive determinations of this parameter. Combining the form factor results at non-zero recoil with recent HPQCD results for the $B\to D\ell \nu$ form factors, we determine the ratios $f_0^{B_s\to D_s}(M_{\pi }^2)/f_0^{B\to D}(M_K^2)=1.000(62)$ and $f_0^{B_s\to D_s}(M_{\pi }^2)/f_0^{B\to D}(M_{\pi }^2)=1.006(62)$. These results give the fragmentation fraction ratios $f_s/f_d=0.310(30{)}_{stat.}(21{)}_{syst.}(6{)}_{theor.}(38{)}_{latt.}$ and $f_s/f_d=0.307(16{)}_{stat.}(21{)}_{syst.}(23{)}_{theor.}(44{)}_{latt.}$, respectively. The fragmentation fraction ratio is an important ingredient in experimental determinations of $B_s$ meson branching fractions at hadron colliders, in particular for the rare decay $\mathcal{B}(B_s\to {\mu }^{+}{\mu }^{-})$. In addition to the form factor results, we make the first prediction of the branching fraction ratio $R(D_s)=\mathcal{B}(B_s\to D_s\tau \nu )/\mathcal{B}(B_s\to D_s\ell \nu )=0.301(6)$, where $\ell$ is an electron or muon. Current experimental measurements of the corresponding ratio for the semileptonic decays of $B$ mesons disagree with Standard Model expectations at the level of nearly four standard deviations. Future experimental measurements of $R(D_s)$ may help understand this discrepancy.

    ↳ hep-lathep-phPRD(2017)·57 citations
14. 14*

    Event generators for $\eta /{\eta }^{\prime }$ decays at BESIII

    Nian Qin🇨🇳 · Zhen-Yu Zhang🇨🇳 · Shuang-Shi Fang🇨🇳 · Xiang Zhou🇨🇳 · Lin-Lin Du🇨🇳 · Hao-Xue Qiao🇨🇳

    The light unflavoured meson $\eta /{\eta }^{\prime }$ decays are valuable for testing non-perturbative quantum chromodynamics and exploring new physics beyond the Standard Model. This paper describes a series of event generators, including $\eta /{\eta }^{\prime }\to \gamma l^{+}{l}^{-}$, $\eta /{\eta }^{\prime }\to \gamma {\pi }^{+}{\pi }^{-}$, ${\eta }^{\prime }\to \omega e^{+}{e}^{-}$, $\eta \to {\pi }^{+}{\pi }^{-}{\pi }^0$, $\eta /{\eta }^{\prime }\to {\pi }^0{\pi }^0{\pi }^0$, ${\eta }^{\prime }\to \eta \pi \pi$ and ${\eta }^{\prime }\to {\pi }^{+}{\pi }^{-}{\pi }^{+}{\pi }^{-}/{\pi }^{+}{\pi }^{-}{\pi }^0{\pi }^0$, which have been developed for investigating $\eta /{\eta }^{\prime }$ decay dynamics. For most of these generators, their usability has been validated in BESIII analyses for determining the detection efficiency, and background studies. The consistency between data and Monte Carlo shows that these generators work well in the BESIII simulation, and will also be useful for ongoing BESIII analyses and other experiments for studying $\eta /{\eta }^{\prime }$ physics.

    ↳ hep-exhep-phCPC(2018)·10 citations
15. 15*

    Dark matter in the Reticulum II dSph: a radio search

    Marco Regis🇮🇹 · Laura Richter🇿🇦 · Sergio Colafrancesco🇿🇦

    We present a deep radio search in the Reticulum II dwarf spheroidal (dSph) galaxy performed with the Australia Telescope Compact Array. Observations were conducted at 16 cm wavelength, with an rms sensitivity of 0.01 mJy/beam, and with the goal of searching for synchrotron emission induced by annihilation or decay of weakly interacting massive particles (WIMPs). Data were complemented with observations on large angular scales taken with the KAT-7 telescope. We find no evidence for a diffuse emission from the dSph and we derive competitive bounds on the WIMP properties. In addition, we detect more than 200 new background radio sources. Among them, we show there are two compelling candidates for being the radio counterpart of the possible gamma-ray emission reported by other groups using Fermi-LAT data.

    ↳ astro-ph.HEastro-ph.GAhep-phJCAP(2017)·56 citations
16. 16*

    New test of weak equivalence principle using polarized light from astrophysical events

    Xue-Feng Wu🇨🇳 · Jun-Jie Wei🇨🇳 · Mi-Xiang Lan🇨🇳 · He Gao🇨🇳 · Zi-Gao Dai🇨🇳 · Peter Mészáros🇺🇸

    Einstein's weak equivalence principle (WEP) states that any freely falling, uncharged test particle follows the same identical trajectory independent of its internal structure and composition. Since the polarization of a photon is considered to be part of its internal structure, we propose that polarized photons from astrophysical transients, such as gamma-ray bursts (GRBs) and fast radio bursts (FRBs), can be used to constrain the accuracy of the WEP through the Shapiro time delay effect. Assuming that the arrival time delays of photons with different polarizations are mainly attributed to the gravitational potential of the Laniakea supercluster of galaxies, we show that a strict upper limit on the differences of the parametrized post-Newtonian parameter $\gamma$ value for the polarized optical emission of GRB 120308A is $\Delta \gamma <1.2\times 10^{-10}$, for the polarized gamma-ray emission of GRB 100826A is $\Delta \gamma <1.2\times 10^{-10}$, and for the polarized radio emission of FRB 150807 is $\Delta \gamma <2.2\times 10^{-16}$. These are the first direct verifications of the WEP for multiband photons with different polarizations. In particular, the result from FRB 150807 provides the most stringent limit to date on a deviation from the WEP, improving by one order of magnitude the previous best result based on Crab pulsar photons with different energies.

    ↳ astro-ph.HEgr-qchep-phhep-thPRD(2017)·21 citations
17. 17*

    Toward pole inflation and attractors in supergravity : Chiral matter field inflation

    Tatsuo Kobayashi🇯🇵 · Osamu Seto🇯🇵 · Takuya H. Tatsuishi🇯🇵

    In string-inspired supergravity theory, Kähler metric of chiral matter fields often has a pole. Such Kähler metric is interesting from the viewpoint of the framework of the pole inflation, where the scalar potential can be stretched out to be flat around the pole for a canonically normalized field and inflation can be realized. However, when Kähler metric has a pole, the scalar potential can also have a pole at the same point in supergravity theory. We study such supergravity models with the pole, and provide numerical analysis of inflationary dynamics and resultant density perturbation. In contrast with usual pole inflation models, inflation in this supergravity based model occurs not on the pole but region apart from the pole. We show that the existence of the pole in the scalar potential is crucial nevertheless. We also examine attractor behavior of our model.

    ↳ hep-thastro-ph.COhep-phPTEP(2017)·26 citations
18. 18*

    On Non-BPS Effective Actions of String Theory

    Ehsan Hatefi🇦🇹

    We discuss some physical prospective of the non-BPS effective actions of type IIA and IIB superstring theories. By dealing with the complete all three and four point functions, including a closed string Ramond-Ramond (in terms of both its field strength and its potential), gauge (scalar) fields as well as a real tachyon and under symmetry structures, we find various restricted world volume and bulk Bianchi identities. The complete forms of the non-BPS scattering amplitudes including their Chan-Paton factors are elaborated. All the singularity structures of the non-BPS amplitudes, their all orders ${\alpha }^{\prime }$ higher derivative corrections, their contact terms and various modified Bianchi identities are derived. Finally we show that scattering amplitudes computed in different super-ghost pictures are compatible when suitable Bianchi identities are imposed on the Ramond-Ramond fields. Moreover, we argue that the higher derivative expansion in powers of the momenta of the tachyon is universal.

    ↳ hep-thgr-qchep-phEPJC(2018)·4 citations
19. 19*

    Astrophysical uncertainties on the local dark matter distribution and direct detection experiments

    Anne M Green🇬🇧

    The differential event rate in Weakly Interacting Massive Particle (WIMP) direct detection experiments depends on the local dark matter density and velocity distribution. Accurate modelling of the local dark matter distribution is therefore required to obtain reliable constraints on the WIMP particle physics properties. Data analyses typically use a simple Standard Halo Model which might not be a good approximation to the real Milky Way (MW) halo. We review observational determinations of the local dark matter density, circular speed and escape speed and also studies of the local dark matter distribution in simulated MW-like galaxies. We discuss the effects of the uncertainties in these quantities on the energy spectrum and its time and direction dependence. Finally we conclude with an overview of various methods for handling these astrophysical uncertainties.

    ↳ astro-ph.COhep-phJ.Phys.G(2017)·122 citations
20. 20*

    Glueballs on the Baryonic Branch of Klebanov-Strassler: dimensional deconstruction and a light scalar particle

    Daniel Elander🇪🇸 · Maurizio Piai🇬🇧

    Within gauge/gravity duality, we compute the scalar and tensor mass spectrum in the boundary theory defined by the five-dimensional sigma-model coupled to gravity obtained by constraining to eight scalars the truncation on T${}^{1,1}$ that corresponds to the Papadopoulos-Tseytlin (PT) ansatz. We study fluctuations around the 1-parameter family of backgrounds that lift to the baryonic branch of the Klebanov-Strassler (KS) system, and interpolates between the KS background and the Maldacena-Nunez one (CVMN). We adopt a gauge invariant formalism in the treatment of the fluctuations that we interpret as states of the dual theory. The tensor spectrum interpolates between the discrete spectrum of the KS background and the continuum spectrum of the CVMN background, in particular showing the emergence of a finite energy range containing a dense set of states, as expected from dimensional deconstruction. The scalar spectrum shows analogous features, and in addition it contains one state that becomes parametrically light far from the origin along the baryonic branch.

    ↳ hep-thhep-phJHEP(2017)·36 citations
21. 21*

    Schwinger-Keldysh Diagrammatics for Primordial Perturbations

    Xingang Chen🇺🇸 · Yi Wang🇨🇳 · Zhong-Zhi Xianyu🇺🇸

    We present a systematic introduction to the diagrammatic method for practical calculations in inflationary cosmology, based on Schwinger-Keldysh path integral formalism. We show in particular that the diagrammatic rules can be derived directly from a classical Lagrangian even in the presence of derivative couplings. Furthermore, we use quasi-single-field inflation as an example to show how this formalism, combined with the trick of mixed propagator, can significantly simplify the calculation of some in-in correlation functions. The resulting bispectrum includes the lighter scalar case ($m<3H/2$) that has been previously studied, and the heavier scalar case ($m>3H/2$) that has not been explicitly computed for this model. The latter provides a concrete example of quantum primordial standard clocks, in which the clock signals can be observably large.

    ↳ hep-thastro-ph.COhep-phJCAP(2017)·221 citations
22. 22*

    Renormalization in large-$N$ QCD is incompatible with open/closed string duality

    Marco Bochicchio🇮🇹

    Solving by a canonical string theory, of closed strings for the glueballs and open strings for the mesons, the 't Hooft large-$N$ expansion of QCD is a long-standing problem that resisted all the attempts despite the advent of the celebrated gauge/gravity duality in the framework of string theory. We demonstrate that in the canonical string framework such a solution does not actually exist because an inconsistency arises between the renormalization properties of the QCD S matrix at large $N$ -- a consequence of the asymptotic freedom (AF) -- and the open/closed duality of the would-be string solution. Specifically, the would-be open-string one-loop corrections to the tree glueball amplitudes must be ultraviolet (UV) divergent. Hence, naively, the inconsistency arises because these amplitudes are dual to tree closed-string diagrams, which are universally believed to be both UV finite -- since they are closed-string tree diagrams -- and infrared finite because of the glueball mass gap. In fact, the inconsistency follows from a low-energy theorem of the NSVZ type that controls the renormalization in QCD-like theories. The inconsistency extends to the would-be canonical string for a vast class of 't Hooft large-$N$ QCD-like theories including $\mathcal{N}=1$ SUSY QCD. We also demonstrate that the presently existing SUSY string models with a mass gap -- such as Klebanov-Strassler, Polchinski-Strassler (PS) and certain PS variants -- cannot contradict the above-mentioned results since they are not asymptotically free. Moreover, we shed light on the way the open/closed string duality may be perturbatively realized in these string models compatibly with a mass gap in the 't Hooft-planar closed-string sector and the low-energy theorem because of the lack of AF. Finally, we suggest a noncanonical way-out for QCD-like theories based on topological strings on noncommutative twistor space.

    ↳ hep-thhep-phPLB(2018)·11 citations
23. 23*

    SppC based energy frontier lepton-proton colliders: luminosity and physics

    A. C. Canbay🇹🇷 · U. Kaya🇹🇷 · B. Ketenoglu🇹🇷 · B. B. Oner🇹🇷 · S. Sultansoy🇹🇷

    In this study, main parameters of Super proton-proton Collider (SppC) based lepton-proton colliders are estimated. For electron beam parameters, highest energy International Linear Collider (ILC) and Plasma Wake Field Accelerator-Linear Collider (PWFA-LC) options are taken into account. For muon beams, 1.5 TeV and 3 TeV center of mass energy Muon Collider parameters are used. In addition, ultimate $\mu$p collider which assumes construction of additional 50 TeV muon ring in the SppC tunnel is considered as well. It is shown that $L_{ep}$ $\sim$ $10^{32}$ $c{m}^{-2}{s}^{-1}$ can be achieved with moderate upgrade of the SppC proton beam parameters. Physics search potential of proposed lepton-proton colliders is illustrated by considering small Bjorken x region as an example of SM physics and resonant production of color octet leptons as an example of BSM physics.

    ↳ physics.acc-phhep-exhep-phAdv.High Energy Phys.(2017)·31 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.